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1/*
2 * linux/mm/memory.c
3 *
4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 */
6
7/*
8 * demand-loading started 01.12.91 - seems it is high on the list of
9 * things wanted, and it should be easy to implement. - Linus
10 */
11
12/*
13 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
14 * pages started 02.12.91, seems to work. - Linus.
15 *
16 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
17 * would have taken more than the 6M I have free, but it worked well as
18 * far as I could see.
19 *
20 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
21 */
22
23/*
24 * Real VM (paging to/from disk) started 18.12.91. Much more work and
25 * thought has to go into this. Oh, well..
26 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
27 * Found it. Everything seems to work now.
28 * 20.12.91 - Ok, making the swap-device changeable like the root.
29 */
30
31/*
32 * 05.04.94 - Multi-page memory management added for v1.1.
33 * Idea by Alex Bligh (alex@cconcepts.co.uk)
34 *
35 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
36 * (Gerhard.Wichert@pdb.siemens.de)
37 *
38 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
39 */
40
41#include <linux/kernel_stat.h>
42#include <linux/mm.h>
43#include <linux/sched/mm.h>
44#include <linux/sched/coredump.h>
45#include <linux/sched/numa_balancing.h>
46#include <linux/sched/task.h>
47#include <linux/hugetlb.h>
48#include <linux/mman.h>
49#include <linux/swap.h>
50#include <linux/highmem.h>
51#include <linux/pagemap.h>
52#include <linux/memremap.h>
53#include <linux/ksm.h>
54#include <linux/rmap.h>
55#include <linux/export.h>
56#include <linux/delayacct.h>
57#include <linux/init.h>
58#include <linux/pfn_t.h>
59#include <linux/writeback.h>
60#include <linux/memcontrol.h>
61#include <linux/mmu_notifier.h>
62#include <linux/swapops.h>
63#include <linux/elf.h>
64#include <linux/gfp.h>
65#include <linux/migrate.h>
66#include <linux/string.h>
67#include <linux/dma-debug.h>
68#include <linux/debugfs.h>
69#include <linux/userfaultfd_k.h>
70#include <linux/dax.h>
71#include <linux/oom.h>
72
73#include <asm/io.h>
74#include <asm/mmu_context.h>
75#include <asm/pgalloc.h>
76#include <linux/uaccess.h>
77#include <asm/tlb.h>
78#include <asm/tlbflush.h>
79#include <asm/pgtable.h>
80
81#include "internal.h"
82
83#if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST)
84#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
85#endif
86
87#ifndef CONFIG_NEED_MULTIPLE_NODES
88/* use the per-pgdat data instead for discontigmem - mbligh */
89unsigned long max_mapnr;
90EXPORT_SYMBOL(max_mapnr);
91
92struct page *mem_map;
93EXPORT_SYMBOL(mem_map);
94#endif
95
96/*
97 * A number of key systems in x86 including ioremap() rely on the assumption
98 * that high_memory defines the upper bound on direct map memory, then end
99 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
100 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
101 * and ZONE_HIGHMEM.
102 */
103void *high_memory;
104EXPORT_SYMBOL(high_memory);
105
106/*
107 * Randomize the address space (stacks, mmaps, brk, etc.).
108 *
109 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
110 * as ancient (libc5 based) binaries can segfault. )
111 */
112int randomize_va_space __read_mostly =
113#ifdef CONFIG_COMPAT_BRK
114 1;
115#else
116 2;
117#endif
118
119static int __init disable_randmaps(char *s)
120{
121 randomize_va_space = 0;
122 return 1;
123}
124__setup("norandmaps", disable_randmaps);
125
126unsigned long zero_pfn __read_mostly;
127EXPORT_SYMBOL(zero_pfn);
128
129unsigned long highest_memmap_pfn __read_mostly;
130
131/*
132 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
133 */
134static int __init init_zero_pfn(void)
135{
136 zero_pfn = page_to_pfn(ZERO_PAGE(0));
137 return 0;
138}
139core_initcall(init_zero_pfn);
140
141
142#if defined(SPLIT_RSS_COUNTING)
143
144void sync_mm_rss(struct mm_struct *mm)
145{
146 int i;
147
148 for (i = 0; i < NR_MM_COUNTERS; i++) {
149 if (current->rss_stat.count[i]) {
150 add_mm_counter(mm, i, current->rss_stat.count[i]);
151 current->rss_stat.count[i] = 0;
152 }
153 }
154 current->rss_stat.events = 0;
155}
156
157static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
158{
159 struct task_struct *task = current;
160
161 if (likely(task->mm == mm))
162 task->rss_stat.count[member] += val;
163 else
164 add_mm_counter(mm, member, val);
165}
166#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
167#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
168
169/* sync counter once per 64 page faults */
170#define TASK_RSS_EVENTS_THRESH (64)
171static void check_sync_rss_stat(struct task_struct *task)
172{
173 if (unlikely(task != current))
174 return;
175 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
176 sync_mm_rss(task->mm);
177}
178#else /* SPLIT_RSS_COUNTING */
179
180#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
181#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
182
183static void check_sync_rss_stat(struct task_struct *task)
184{
185}
186
187#endif /* SPLIT_RSS_COUNTING */
188
189#ifdef HAVE_GENERIC_MMU_GATHER
190
191static bool tlb_next_batch(struct mmu_gather *tlb)
192{
193 struct mmu_gather_batch *batch;
194
195 batch = tlb->active;
196 if (batch->next) {
197 tlb->active = batch->next;
198 return true;
199 }
200
201 if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
202 return false;
203
204 batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
205 if (!batch)
206 return false;
207
208 tlb->batch_count++;
209 batch->next = NULL;
210 batch->nr = 0;
211 batch->max = MAX_GATHER_BATCH;
212
213 tlb->active->next = batch;
214 tlb->active = batch;
215
216 return true;
217}
218
219void arch_tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
220 unsigned long start, unsigned long end)
221{
222 tlb->mm = mm;
223
224 /* Is it from 0 to ~0? */
225 tlb->fullmm = !(start | (end+1));
226 tlb->need_flush_all = 0;
227 tlb->local.next = NULL;
228 tlb->local.nr = 0;
229 tlb->local.max = ARRAY_SIZE(tlb->__pages);
230 tlb->active = &tlb->local;
231 tlb->batch_count = 0;
232
233#ifdef CONFIG_HAVE_RCU_TABLE_FREE
234 tlb->batch = NULL;
235#endif
236 tlb->page_size = 0;
237
238 __tlb_reset_range(tlb);
239}
240
241static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
242{
243 if (!tlb->end)
244 return;
245
246 tlb_flush(tlb);
247 mmu_notifier_invalidate_range(tlb->mm, tlb->start, tlb->end);
248#ifdef CONFIG_HAVE_RCU_TABLE_FREE
249 tlb_table_flush(tlb);
250#endif
251 __tlb_reset_range(tlb);
252}
253
254static void tlb_flush_mmu_free(struct mmu_gather *tlb)
255{
256 struct mmu_gather_batch *batch;
257
258 for (batch = &tlb->local; batch && batch->nr; batch = batch->next) {
259 free_pages_and_swap_cache(batch->pages, batch->nr);
260 batch->nr = 0;
261 }
262 tlb->active = &tlb->local;
263}
264
265void tlb_flush_mmu(struct mmu_gather *tlb)
266{
267 tlb_flush_mmu_tlbonly(tlb);
268 tlb_flush_mmu_free(tlb);
269}
270
271/* tlb_finish_mmu
272 * Called at the end of the shootdown operation to free up any resources
273 * that were required.
274 */
275void arch_tlb_finish_mmu(struct mmu_gather *tlb,
276 unsigned long start, unsigned long end, bool force)
277{
278 struct mmu_gather_batch *batch, *next;
279
280 if (force)
281 __tlb_adjust_range(tlb, start, end - start);
282
283 tlb_flush_mmu(tlb);
284
285 /* keep the page table cache within bounds */
286 check_pgt_cache();
287
288 for (batch = tlb->local.next; batch; batch = next) {
289 next = batch->next;
290 free_pages((unsigned long)batch, 0);
291 }
292 tlb->local.next = NULL;
293}
294
295/* __tlb_remove_page
296 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
297 * handling the additional races in SMP caused by other CPUs caching valid
298 * mappings in their TLBs. Returns the number of free page slots left.
299 * When out of page slots we must call tlb_flush_mmu().
300 *returns true if the caller should flush.
301 */
302bool __tlb_remove_page_size(struct mmu_gather *tlb, struct page *page, int page_size)
303{
304 struct mmu_gather_batch *batch;
305
306 VM_BUG_ON(!tlb->end);
307 VM_WARN_ON(tlb->page_size != page_size);
308
309 batch = tlb->active;
310 /*
311 * Add the page and check if we are full. If so
312 * force a flush.
313 */
314 batch->pages[batch->nr++] = page;
315 if (batch->nr == batch->max) {
316 if (!tlb_next_batch(tlb))
317 return true;
318 batch = tlb->active;
319 }
320 VM_BUG_ON_PAGE(batch->nr > batch->max, page);
321
322 return false;
323}
324
325#endif /* HAVE_GENERIC_MMU_GATHER */
326
327#ifdef CONFIG_HAVE_RCU_TABLE_FREE
328
329/*
330 * See the comment near struct mmu_table_batch.
331 */
332
333static void tlb_remove_table_smp_sync(void *arg)
334{
335 /* Simply deliver the interrupt */
336}
337
338static void tlb_remove_table_one(void *table)
339{
340 /*
341 * This isn't an RCU grace period and hence the page-tables cannot be
342 * assumed to be actually RCU-freed.
343 *
344 * It is however sufficient for software page-table walkers that rely on
345 * IRQ disabling. See the comment near struct mmu_table_batch.
346 */
347 smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
348 __tlb_remove_table(table);
349}
350
351static void tlb_remove_table_rcu(struct rcu_head *head)
352{
353 struct mmu_table_batch *batch;
354 int i;
355
356 batch = container_of(head, struct mmu_table_batch, rcu);
357
358 for (i = 0; i < batch->nr; i++)
359 __tlb_remove_table(batch->tables[i]);
360
361 free_page((unsigned long)batch);
362}
363
364void tlb_table_flush(struct mmu_gather *tlb)
365{
366 struct mmu_table_batch **batch = &tlb->batch;
367
368 if (*batch) {
369 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
370 *batch = NULL;
371 }
372}
373
374void tlb_remove_table(struct mmu_gather *tlb, void *table)
375{
376 struct mmu_table_batch **batch = &tlb->batch;
377
378 /*
379 * When there's less then two users of this mm there cannot be a
380 * concurrent page-table walk.
381 */
382 if (atomic_read(&tlb->mm->mm_users) < 2) {
383 __tlb_remove_table(table);
384 return;
385 }
386
387 if (*batch == NULL) {
388 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
389 if (*batch == NULL) {
390 tlb_remove_table_one(table);
391 return;
392 }
393 (*batch)->nr = 0;
394 }
395 (*batch)->tables[(*batch)->nr++] = table;
396 if ((*batch)->nr == MAX_TABLE_BATCH)
397 tlb_table_flush(tlb);
398}
399
400#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
401
402/**
403 * tlb_gather_mmu - initialize an mmu_gather structure for page-table tear-down
404 * @tlb: the mmu_gather structure to initialize
405 * @mm: the mm_struct of the target address space
406 * @start: start of the region that will be removed from the page-table
407 * @end: end of the region that will be removed from the page-table
408 *
409 * Called to initialize an (on-stack) mmu_gather structure for page-table
410 * tear-down from @mm. The @start and @end are set to 0 and -1
411 * respectively when @mm is without users and we're going to destroy
412 * the full address space (exit/execve).
413 */
414void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm,
415 unsigned long start, unsigned long end)
416{
417 arch_tlb_gather_mmu(tlb, mm, start, end);
418 inc_tlb_flush_pending(tlb->mm);
419}
420
421void tlb_finish_mmu(struct mmu_gather *tlb,
422 unsigned long start, unsigned long end)
423{
424 /*
425 * If there are parallel threads are doing PTE changes on same range
426 * under non-exclusive lock(e.g., mmap_sem read-side) but defer TLB
427 * flush by batching, a thread has stable TLB entry can fail to flush
428 * the TLB by observing pte_none|!pte_dirty, for example so flush TLB
429 * forcefully if we detect parallel PTE batching threads.
430 */
431 bool force = mm_tlb_flush_nested(tlb->mm);
432
433 arch_tlb_finish_mmu(tlb, start, end, force);
434 dec_tlb_flush_pending(tlb->mm);
435}
436
437/*
438 * Note: this doesn't free the actual pages themselves. That
439 * has been handled earlier when unmapping all the memory regions.
440 */
441static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
442 unsigned long addr)
443{
444 pgtable_t token = pmd_pgtable(*pmd);
445 pmd_clear(pmd);
446 pte_free_tlb(tlb, token, addr);
447 mm_dec_nr_ptes(tlb->mm);
448}
449
450static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
451 unsigned long addr, unsigned long end,
452 unsigned long floor, unsigned long ceiling)
453{
454 pmd_t *pmd;
455 unsigned long next;
456 unsigned long start;
457
458 start = addr;
459 pmd = pmd_offset(pud, addr);
460 do {
461 next = pmd_addr_end(addr, end);
462 if (pmd_none_or_clear_bad(pmd))
463 continue;
464 free_pte_range(tlb, pmd, addr);
465 } while (pmd++, addr = next, addr != end);
466
467 start &= PUD_MASK;
468 if (start < floor)
469 return;
470 if (ceiling) {
471 ceiling &= PUD_MASK;
472 if (!ceiling)
473 return;
474 }
475 if (end - 1 > ceiling - 1)
476 return;
477
478 pmd = pmd_offset(pud, start);
479 pud_clear(pud);
480 pmd_free_tlb(tlb, pmd, start);
481 mm_dec_nr_pmds(tlb->mm);
482}
483
484static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
485 unsigned long addr, unsigned long end,
486 unsigned long floor, unsigned long ceiling)
487{
488 pud_t *pud;
489 unsigned long next;
490 unsigned long start;
491
492 start = addr;
493 pud = pud_offset(p4d, addr);
494 do {
495 next = pud_addr_end(addr, end);
496 if (pud_none_or_clear_bad(pud))
497 continue;
498 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
499 } while (pud++, addr = next, addr != end);
500
501 start &= P4D_MASK;
502 if (start < floor)
503 return;
504 if (ceiling) {
505 ceiling &= P4D_MASK;
506 if (!ceiling)
507 return;
508 }
509 if (end - 1 > ceiling - 1)
510 return;
511
512 pud = pud_offset(p4d, start);
513 p4d_clear(p4d);
514 pud_free_tlb(tlb, pud, start);
515 mm_dec_nr_puds(tlb->mm);
516}
517
518static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
519 unsigned long addr, unsigned long end,
520 unsigned long floor, unsigned long ceiling)
521{
522 p4d_t *p4d;
523 unsigned long next;
524 unsigned long start;
525
526 start = addr;
527 p4d = p4d_offset(pgd, addr);
528 do {
529 next = p4d_addr_end(addr, end);
530 if (p4d_none_or_clear_bad(p4d))
531 continue;
532 free_pud_range(tlb, p4d, addr, next, floor, ceiling);
533 } while (p4d++, addr = next, addr != end);
534
535 start &= PGDIR_MASK;
536 if (start < floor)
537 return;
538 if (ceiling) {
539 ceiling &= PGDIR_MASK;
540 if (!ceiling)
541 return;
542 }
543 if (end - 1 > ceiling - 1)
544 return;
545
546 p4d = p4d_offset(pgd, start);
547 pgd_clear(pgd);
548 p4d_free_tlb(tlb, p4d, start);
549}
550
551/*
552 * This function frees user-level page tables of a process.
553 */
554void free_pgd_range(struct mmu_gather *tlb,
555 unsigned long addr, unsigned long end,
556 unsigned long floor, unsigned long ceiling)
557{
558 pgd_t *pgd;
559 unsigned long next;
560
561 /*
562 * The next few lines have given us lots of grief...
563 *
564 * Why are we testing PMD* at this top level? Because often
565 * there will be no work to do at all, and we'd prefer not to
566 * go all the way down to the bottom just to discover that.
567 *
568 * Why all these "- 1"s? Because 0 represents both the bottom
569 * of the address space and the top of it (using -1 for the
570 * top wouldn't help much: the masks would do the wrong thing).
571 * The rule is that addr 0 and floor 0 refer to the bottom of
572 * the address space, but end 0 and ceiling 0 refer to the top
573 * Comparisons need to use "end - 1" and "ceiling - 1" (though
574 * that end 0 case should be mythical).
575 *
576 * Wherever addr is brought up or ceiling brought down, we must
577 * be careful to reject "the opposite 0" before it confuses the
578 * subsequent tests. But what about where end is brought down
579 * by PMD_SIZE below? no, end can't go down to 0 there.
580 *
581 * Whereas we round start (addr) and ceiling down, by different
582 * masks at different levels, in order to test whether a table
583 * now has no other vmas using it, so can be freed, we don't
584 * bother to round floor or end up - the tests don't need that.
585 */
586
587 addr &= PMD_MASK;
588 if (addr < floor) {
589 addr += PMD_SIZE;
590 if (!addr)
591 return;
592 }
593 if (ceiling) {
594 ceiling &= PMD_MASK;
595 if (!ceiling)
596 return;
597 }
598 if (end - 1 > ceiling - 1)
599 end -= PMD_SIZE;
600 if (addr > end - 1)
601 return;
602 /*
603 * We add page table cache pages with PAGE_SIZE,
604 * (see pte_free_tlb()), flush the tlb if we need
605 */
606 tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
607 pgd = pgd_offset(tlb->mm, addr);
608 do {
609 next = pgd_addr_end(addr, end);
610 if (pgd_none_or_clear_bad(pgd))
611 continue;
612 free_p4d_range(tlb, pgd, addr, next, floor, ceiling);
613 } while (pgd++, addr = next, addr != end);
614}
615
616void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
617 unsigned long floor, unsigned long ceiling)
618{
619 while (vma) {
620 struct vm_area_struct *next = vma->vm_next;
621 unsigned long addr = vma->vm_start;
622
623 /*
624 * Hide vma from rmap and truncate_pagecache before freeing
625 * pgtables
626 */
627 unlink_anon_vmas(vma);
628 unlink_file_vma(vma);
629
630 if (is_vm_hugetlb_page(vma)) {
631 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
632 floor, next ? next->vm_start : ceiling);
633 } else {
634 /*
635 * Optimization: gather nearby vmas into one call down
636 */
637 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
638 && !is_vm_hugetlb_page(next)) {
639 vma = next;
640 next = vma->vm_next;
641 unlink_anon_vmas(vma);
642 unlink_file_vma(vma);
643 }
644 free_pgd_range(tlb, addr, vma->vm_end,
645 floor, next ? next->vm_start : ceiling);
646 }
647 vma = next;
648 }
649}
650
651int __pte_alloc(struct mm_struct *mm, pmd_t *pmd, unsigned long address)
652{
653 spinlock_t *ptl;
654 pgtable_t new = pte_alloc_one(mm, address);
655 if (!new)
656 return -ENOMEM;
657
658 /*
659 * Ensure all pte setup (eg. pte page lock and page clearing) are
660 * visible before the pte is made visible to other CPUs by being
661 * put into page tables.
662 *
663 * The other side of the story is the pointer chasing in the page
664 * table walking code (when walking the page table without locking;
665 * ie. most of the time). Fortunately, these data accesses consist
666 * of a chain of data-dependent loads, meaning most CPUs (alpha
667 * being the notable exception) will already guarantee loads are
668 * seen in-order. See the alpha page table accessors for the
669 * smp_read_barrier_depends() barriers in page table walking code.
670 */
671 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
672
673 ptl = pmd_lock(mm, pmd);
674 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
675 mm_inc_nr_ptes(mm);
676 pmd_populate(mm, pmd, new);
677 new = NULL;
678 }
679 spin_unlock(ptl);
680 if (new)
681 pte_free(mm, new);
682 return 0;
683}
684
685int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
686{
687 pte_t *new = pte_alloc_one_kernel(&init_mm, address);
688 if (!new)
689 return -ENOMEM;
690
691 smp_wmb(); /* See comment in __pte_alloc */
692
693 spin_lock(&init_mm.page_table_lock);
694 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
695 pmd_populate_kernel(&init_mm, pmd, new);
696 new = NULL;
697 }
698 spin_unlock(&init_mm.page_table_lock);
699 if (new)
700 pte_free_kernel(&init_mm, new);
701 return 0;
702}
703
704static inline void init_rss_vec(int *rss)
705{
706 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
707}
708
709static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
710{
711 int i;
712
713 if (current->mm == mm)
714 sync_mm_rss(mm);
715 for (i = 0; i < NR_MM_COUNTERS; i++)
716 if (rss[i])
717 add_mm_counter(mm, i, rss[i]);
718}
719
720/*
721 * This function is called to print an error when a bad pte
722 * is found. For example, we might have a PFN-mapped pte in
723 * a region that doesn't allow it.
724 *
725 * The calling function must still handle the error.
726 */
727static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
728 pte_t pte, struct page *page)
729{
730 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
731 p4d_t *p4d = p4d_offset(pgd, addr);
732 pud_t *pud = pud_offset(p4d, addr);
733 pmd_t *pmd = pmd_offset(pud, addr);
734 struct address_space *mapping;
735 pgoff_t index;
736 static unsigned long resume;
737 static unsigned long nr_shown;
738 static unsigned long nr_unshown;
739
740 /*
741 * Allow a burst of 60 reports, then keep quiet for that minute;
742 * or allow a steady drip of one report per second.
743 */
744 if (nr_shown == 60) {
745 if (time_before(jiffies, resume)) {
746 nr_unshown++;
747 return;
748 }
749 if (nr_unshown) {
750 pr_alert("BUG: Bad page map: %lu messages suppressed\n",
751 nr_unshown);
752 nr_unshown = 0;
753 }
754 nr_shown = 0;
755 }
756 if (nr_shown++ == 0)
757 resume = jiffies + 60 * HZ;
758
759 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
760 index = linear_page_index(vma, addr);
761
762 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
763 current->comm,
764 (long long)pte_val(pte), (long long)pmd_val(*pmd));
765 if (page)
766 dump_page(page, "bad pte");
767 pr_alert("addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
768 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
769 pr_alert("file:%pD fault:%pf mmap:%pf readpage:%pf\n",
770 vma->vm_file,
771 vma->vm_ops ? vma->vm_ops->fault : NULL,
772 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
773 mapping ? mapping->a_ops->readpage : NULL);
774 dump_stack();
775 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
776}
777
778/*
779 * vm_normal_page -- This function gets the "struct page" associated with a pte.
780 *
781 * "Special" mappings do not wish to be associated with a "struct page" (either
782 * it doesn't exist, or it exists but they don't want to touch it). In this
783 * case, NULL is returned here. "Normal" mappings do have a struct page.
784 *
785 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
786 * pte bit, in which case this function is trivial. Secondly, an architecture
787 * may not have a spare pte bit, which requires a more complicated scheme,
788 * described below.
789 *
790 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
791 * special mapping (even if there are underlying and valid "struct pages").
792 * COWed pages of a VM_PFNMAP are always normal.
793 *
794 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
795 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
796 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
797 * mapping will always honor the rule
798 *
799 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
800 *
801 * And for normal mappings this is false.
802 *
803 * This restricts such mappings to be a linear translation from virtual address
804 * to pfn. To get around this restriction, we allow arbitrary mappings so long
805 * as the vma is not a COW mapping; in that case, we know that all ptes are
806 * special (because none can have been COWed).
807 *
808 *
809 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
810 *
811 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
812 * page" backing, however the difference is that _all_ pages with a struct
813 * page (that is, those where pfn_valid is true) are refcounted and considered
814 * normal pages by the VM. The disadvantage is that pages are refcounted
815 * (which can be slower and simply not an option for some PFNMAP users). The
816 * advantage is that we don't have to follow the strict linearity rule of
817 * PFNMAP mappings in order to support COWable mappings.
818 *
819 */
820#ifdef __HAVE_ARCH_PTE_SPECIAL
821# define HAVE_PTE_SPECIAL 1
822#else
823# define HAVE_PTE_SPECIAL 0
824#endif
825struct page *_vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
826 pte_t pte, bool with_public_device)
827{
828 unsigned long pfn = pte_pfn(pte);
829
830 if (HAVE_PTE_SPECIAL) {
831 if (likely(!pte_special(pte)))
832 goto check_pfn;
833 if (vma->vm_ops && vma->vm_ops->find_special_page)
834 return vma->vm_ops->find_special_page(vma, addr);
835 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
836 return NULL;
837 if (is_zero_pfn(pfn))
838 return NULL;
839
840 /*
841 * Device public pages are special pages (they are ZONE_DEVICE
842 * pages but different from persistent memory). They behave
843 * allmost like normal pages. The difference is that they are
844 * not on the lru and thus should never be involve with any-
845 * thing that involve lru manipulation (mlock, numa balancing,
846 * ...).
847 *
848 * This is why we still want to return NULL for such page from
849 * vm_normal_page() so that we do not have to special case all
850 * call site of vm_normal_page().
851 */
852 if (likely(pfn <= highest_memmap_pfn)) {
853 struct page *page = pfn_to_page(pfn);
854
855 if (is_device_public_page(page)) {
856 if (with_public_device)
857 return page;
858 return NULL;
859 }
860 }
861 print_bad_pte(vma, addr, pte, NULL);
862 return NULL;
863 }
864
865 /* !HAVE_PTE_SPECIAL case follows: */
866
867 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
868 if (vma->vm_flags & VM_MIXEDMAP) {
869 if (!pfn_valid(pfn))
870 return NULL;
871 goto out;
872 } else {
873 unsigned long off;
874 off = (addr - vma->vm_start) >> PAGE_SHIFT;
875 if (pfn == vma->vm_pgoff + off)
876 return NULL;
877 if (!is_cow_mapping(vma->vm_flags))
878 return NULL;
879 }
880 }
881
882 if (is_zero_pfn(pfn))
883 return NULL;
884check_pfn:
885 if (unlikely(pfn > highest_memmap_pfn)) {
886 print_bad_pte(vma, addr, pte, NULL);
887 return NULL;
888 }
889
890 /*
891 * NOTE! We still have PageReserved() pages in the page tables.
892 * eg. VDSO mappings can cause them to exist.
893 */
894out:
895 return pfn_to_page(pfn);
896}
897
898#ifdef CONFIG_TRANSPARENT_HUGEPAGE
899struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
900 pmd_t pmd)
901{
902 unsigned long pfn = pmd_pfn(pmd);
903
904 /*
905 * There is no pmd_special() but there may be special pmds, e.g.
906 * in a direct-access (dax) mapping, so let's just replicate the
907 * !HAVE_PTE_SPECIAL case from vm_normal_page() here.
908 */
909 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
910 if (vma->vm_flags & VM_MIXEDMAP) {
911 if (!pfn_valid(pfn))
912 return NULL;
913 goto out;
914 } else {
915 unsigned long off;
916 off = (addr - vma->vm_start) >> PAGE_SHIFT;
917 if (pfn == vma->vm_pgoff + off)
918 return NULL;
919 if (!is_cow_mapping(vma->vm_flags))
920 return NULL;
921 }
922 }
923
924 if (is_zero_pfn(pfn))
925 return NULL;
926 if (unlikely(pfn > highest_memmap_pfn))
927 return NULL;
928
929 /*
930 * NOTE! We still have PageReserved() pages in the page tables.
931 * eg. VDSO mappings can cause them to exist.
932 */
933out:
934 return pfn_to_page(pfn);
935}
936#endif
937
938/*
939 * copy one vm_area from one task to the other. Assumes the page tables
940 * already present in the new task to be cleared in the whole range
941 * covered by this vma.
942 */
943
944static inline unsigned long
945copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
946 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
947 unsigned long addr, int *rss)
948{
949 unsigned long vm_flags = vma->vm_flags;
950 pte_t pte = *src_pte;
951 struct page *page;
952
953 /* pte contains position in swap or file, so copy. */
954 if (unlikely(!pte_present(pte))) {
955 swp_entry_t entry = pte_to_swp_entry(pte);
956
957 if (likely(!non_swap_entry(entry))) {
958 if (swap_duplicate(entry) < 0)
959 return entry.val;
960
961 /* make sure dst_mm is on swapoff's mmlist. */
962 if (unlikely(list_empty(&dst_mm->mmlist))) {
963 spin_lock(&mmlist_lock);
964 if (list_empty(&dst_mm->mmlist))
965 list_add(&dst_mm->mmlist,
966 &src_mm->mmlist);
967 spin_unlock(&mmlist_lock);
968 }
969 rss[MM_SWAPENTS]++;
970 } else if (is_migration_entry(entry)) {
971 page = migration_entry_to_page(entry);
972
973 rss[mm_counter(page)]++;
974
975 if (is_write_migration_entry(entry) &&
976 is_cow_mapping(vm_flags)) {
977 /*
978 * COW mappings require pages in both
979 * parent and child to be set to read.
980 */
981 make_migration_entry_read(&entry);
982 pte = swp_entry_to_pte(entry);
983 if (pte_swp_soft_dirty(*src_pte))
984 pte = pte_swp_mksoft_dirty(pte);
985 set_pte_at(src_mm, addr, src_pte, pte);
986 }
987 } else if (is_device_private_entry(entry)) {
988 page = device_private_entry_to_page(entry);
989
990 /*
991 * Update rss count even for unaddressable pages, as
992 * they should treated just like normal pages in this
993 * respect.
994 *
995 * We will likely want to have some new rss counters
996 * for unaddressable pages, at some point. But for now
997 * keep things as they are.
998 */
999 get_page(page);
1000 rss[mm_counter(page)]++;
1001 page_dup_rmap(page, false);
1002
1003 /*
1004 * We do not preserve soft-dirty information, because so
1005 * far, checkpoint/restore is the only feature that
1006 * requires that. And checkpoint/restore does not work
1007 * when a device driver is involved (you cannot easily
1008 * save and restore device driver state).
1009 */
1010 if (is_write_device_private_entry(entry) &&
1011 is_cow_mapping(vm_flags)) {
1012 make_device_private_entry_read(&entry);
1013 pte = swp_entry_to_pte(entry);
1014 set_pte_at(src_mm, addr, src_pte, pte);
1015 }
1016 }
1017 goto out_set_pte;
1018 }
1019
1020 /*
1021 * If it's a COW mapping, write protect it both
1022 * in the parent and the child
1023 */
1024 if (is_cow_mapping(vm_flags)) {
1025 ptep_set_wrprotect(src_mm, addr, src_pte);
1026 pte = pte_wrprotect(pte);
1027 }
1028
1029 /*
1030 * If it's a shared mapping, mark it clean in
1031 * the child
1032 */
1033 if (vm_flags & VM_SHARED)
1034 pte = pte_mkclean(pte);
1035 pte = pte_mkold(pte);
1036
1037 page = vm_normal_page(vma, addr, pte);
1038 if (page) {
1039 get_page(page);
1040 page_dup_rmap(page, false);
1041 rss[mm_counter(page)]++;
1042 } else if (pte_devmap(pte)) {
1043 page = pte_page(pte);
1044
1045 /*
1046 * Cache coherent device memory behave like regular page and
1047 * not like persistent memory page. For more informations see
1048 * MEMORY_DEVICE_CACHE_COHERENT in memory_hotplug.h
1049 */
1050 if (is_device_public_page(page)) {
1051 get_page(page);
1052 page_dup_rmap(page, false);
1053 rss[mm_counter(page)]++;
1054 }
1055 }
1056
1057out_set_pte:
1058 set_pte_at(dst_mm, addr, dst_pte, pte);
1059 return 0;
1060}
1061
1062static int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1063 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
1064 unsigned long addr, unsigned long end)
1065{
1066 pte_t *orig_src_pte, *orig_dst_pte;
1067 pte_t *src_pte, *dst_pte;
1068 spinlock_t *src_ptl, *dst_ptl;
1069 int progress = 0;
1070 int rss[NR_MM_COUNTERS];
1071 swp_entry_t entry = (swp_entry_t){0};
1072
1073again:
1074 init_rss_vec(rss);
1075
1076 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
1077 if (!dst_pte)
1078 return -ENOMEM;
1079 src_pte = pte_offset_map(src_pmd, addr);
1080 src_ptl = pte_lockptr(src_mm, src_pmd);
1081 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1082 orig_src_pte = src_pte;
1083 orig_dst_pte = dst_pte;
1084 arch_enter_lazy_mmu_mode();
1085
1086 do {
1087 /*
1088 * We are holding two locks at this point - either of them
1089 * could generate latencies in another task on another CPU.
1090 */
1091 if (progress >= 32) {
1092 progress = 0;
1093 if (need_resched() ||
1094 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
1095 break;
1096 }
1097 if (pte_none(*src_pte)) {
1098 progress++;
1099 continue;
1100 }
1101 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
1102 vma, addr, rss);
1103 if (entry.val)
1104 break;
1105 progress += 8;
1106 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
1107
1108 arch_leave_lazy_mmu_mode();
1109 spin_unlock(src_ptl);
1110 pte_unmap(orig_src_pte);
1111 add_mm_rss_vec(dst_mm, rss);
1112 pte_unmap_unlock(orig_dst_pte, dst_ptl);
1113 cond_resched();
1114
1115 if (entry.val) {
1116 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
1117 return -ENOMEM;
1118 progress = 0;
1119 }
1120 if (addr != end)
1121 goto again;
1122 return 0;
1123}
1124
1125static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1126 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
1127 unsigned long addr, unsigned long end)
1128{
1129 pmd_t *src_pmd, *dst_pmd;
1130 unsigned long next;
1131
1132 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
1133 if (!dst_pmd)
1134 return -ENOMEM;
1135 src_pmd = pmd_offset(src_pud, addr);
1136 do {
1137 next = pmd_addr_end(addr, end);
1138 if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
1139 || pmd_devmap(*src_pmd)) {
1140 int err;
1141 VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, vma);
1142 err = copy_huge_pmd(dst_mm, src_mm,
1143 dst_pmd, src_pmd, addr, vma);
1144 if (err == -ENOMEM)
1145 return -ENOMEM;
1146 if (!err)
1147 continue;
1148 /* fall through */
1149 }
1150 if (pmd_none_or_clear_bad(src_pmd))
1151 continue;
1152 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
1153 vma, addr, next))
1154 return -ENOMEM;
1155 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1156 return 0;
1157}
1158
1159static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1160 p4d_t *dst_p4d, p4d_t *src_p4d, struct vm_area_struct *vma,
1161 unsigned long addr, unsigned long end)
1162{
1163 pud_t *src_pud, *dst_pud;
1164 unsigned long next;
1165
1166 dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
1167 if (!dst_pud)
1168 return -ENOMEM;
1169 src_pud = pud_offset(src_p4d, addr);
1170 do {
1171 next = pud_addr_end(addr, end);
1172 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
1173 int err;
1174
1175 VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, vma);
1176 err = copy_huge_pud(dst_mm, src_mm,
1177 dst_pud, src_pud, addr, vma);
1178 if (err == -ENOMEM)
1179 return -ENOMEM;
1180 if (!err)
1181 continue;
1182 /* fall through */
1183 }
1184 if (pud_none_or_clear_bad(src_pud))
1185 continue;
1186 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1187 vma, addr, next))
1188 return -ENOMEM;
1189 } while (dst_pud++, src_pud++, addr = next, addr != end);
1190 return 0;
1191}
1192
1193static inline int copy_p4d_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1194 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
1195 unsigned long addr, unsigned long end)
1196{
1197 p4d_t *src_p4d, *dst_p4d;
1198 unsigned long next;
1199
1200 dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
1201 if (!dst_p4d)
1202 return -ENOMEM;
1203 src_p4d = p4d_offset(src_pgd, addr);
1204 do {
1205 next = p4d_addr_end(addr, end);
1206 if (p4d_none_or_clear_bad(src_p4d))
1207 continue;
1208 if (copy_pud_range(dst_mm, src_mm, dst_p4d, src_p4d,
1209 vma, addr, next))
1210 return -ENOMEM;
1211 } while (dst_p4d++, src_p4d++, addr = next, addr != end);
1212 return 0;
1213}
1214
1215int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1216 struct vm_area_struct *vma)
1217{
1218 pgd_t *src_pgd, *dst_pgd;
1219 unsigned long next;
1220 unsigned long addr = vma->vm_start;
1221 unsigned long end = vma->vm_end;
1222 unsigned long mmun_start; /* For mmu_notifiers */
1223 unsigned long mmun_end; /* For mmu_notifiers */
1224 bool is_cow;
1225 int ret;
1226
1227 /*
1228 * Don't copy ptes where a page fault will fill them correctly.
1229 * Fork becomes much lighter when there are big shared or private
1230 * readonly mappings. The tradeoff is that copy_page_range is more
1231 * efficient than faulting.
1232 */
1233 if (!(vma->vm_flags & (VM_HUGETLB | VM_PFNMAP | VM_MIXEDMAP)) &&
1234 !vma->anon_vma)
1235 return 0;
1236
1237 if (is_vm_hugetlb_page(vma))
1238 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1239
1240 if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1241 /*
1242 * We do not free on error cases below as remove_vma
1243 * gets called on error from higher level routine
1244 */
1245 ret = track_pfn_copy(vma);
1246 if (ret)
1247 return ret;
1248 }
1249
1250 /*
1251 * We need to invalidate the secondary MMU mappings only when
1252 * there could be a permission downgrade on the ptes of the
1253 * parent mm. And a permission downgrade will only happen if
1254 * is_cow_mapping() returns true.
1255 */
1256 is_cow = is_cow_mapping(vma->vm_flags);
1257 mmun_start = addr;
1258 mmun_end = end;
1259 if (is_cow)
1260 mmu_notifier_invalidate_range_start(src_mm, mmun_start,
1261 mmun_end);
1262
1263 ret = 0;
1264 dst_pgd = pgd_offset(dst_mm, addr);
1265 src_pgd = pgd_offset(src_mm, addr);
1266 do {
1267 next = pgd_addr_end(addr, end);
1268 if (pgd_none_or_clear_bad(src_pgd))
1269 continue;
1270 if (unlikely(copy_p4d_range(dst_mm, src_mm, dst_pgd, src_pgd,
1271 vma, addr, next))) {
1272 ret = -ENOMEM;
1273 break;
1274 }
1275 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1276
1277 if (is_cow)
1278 mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
1279 return ret;
1280}
1281
1282static unsigned long zap_pte_range(struct mmu_gather *tlb,
1283 struct vm_area_struct *vma, pmd_t *pmd,
1284 unsigned long addr, unsigned long end,
1285 struct zap_details *details)
1286{
1287 struct mm_struct *mm = tlb->mm;
1288 int force_flush = 0;
1289 int rss[NR_MM_COUNTERS];
1290 spinlock_t *ptl;
1291 pte_t *start_pte;
1292 pte_t *pte;
1293 swp_entry_t entry;
1294
1295 tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
1296again:
1297 init_rss_vec(rss);
1298 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1299 pte = start_pte;
1300 flush_tlb_batched_pending(mm);
1301 arch_enter_lazy_mmu_mode();
1302 do {
1303 pte_t ptent = *pte;
1304 if (pte_none(ptent))
1305 continue;
1306
1307 if (pte_present(ptent)) {
1308 struct page *page;
1309
1310 page = _vm_normal_page(vma, addr, ptent, true);
1311 if (unlikely(details) && page) {
1312 /*
1313 * unmap_shared_mapping_pages() wants to
1314 * invalidate cache without truncating:
1315 * unmap shared but keep private pages.
1316 */
1317 if (details->check_mapping &&
1318 details->check_mapping != page_rmapping(page))
1319 continue;
1320 }
1321 ptent = ptep_get_and_clear_full(mm, addr, pte,
1322 tlb->fullmm);
1323 tlb_remove_tlb_entry(tlb, pte, addr);
1324 if (unlikely(!page))
1325 continue;
1326
1327 if (!PageAnon(page)) {
1328 if (pte_dirty(ptent)) {
1329 force_flush = 1;
1330 set_page_dirty(page);
1331 }
1332 if (pte_young(ptent) &&
1333 likely(!(vma->vm_flags & VM_SEQ_READ)))
1334 mark_page_accessed(page);
1335 }
1336 rss[mm_counter(page)]--;
1337 page_remove_rmap(page, false);
1338 if (unlikely(page_mapcount(page) < 0))
1339 print_bad_pte(vma, addr, ptent, page);
1340 if (unlikely(__tlb_remove_page(tlb, page))) {
1341 force_flush = 1;
1342 addr += PAGE_SIZE;
1343 break;
1344 }
1345 continue;
1346 }
1347
1348 entry = pte_to_swp_entry(ptent);
1349 if (non_swap_entry(entry) && is_device_private_entry(entry)) {
1350 struct page *page = device_private_entry_to_page(entry);
1351
1352 if (unlikely(details && details->check_mapping)) {
1353 /*
1354 * unmap_shared_mapping_pages() wants to
1355 * invalidate cache without truncating:
1356 * unmap shared but keep private pages.
1357 */
1358 if (details->check_mapping !=
1359 page_rmapping(page))
1360 continue;
1361 }
1362
1363 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1364 rss[mm_counter(page)]--;
1365 page_remove_rmap(page, false);
1366 put_page(page);
1367 continue;
1368 }
1369
1370 /* If details->check_mapping, we leave swap entries. */
1371 if (unlikely(details))
1372 continue;
1373
1374 entry = pte_to_swp_entry(ptent);
1375 if (!non_swap_entry(entry))
1376 rss[MM_SWAPENTS]--;
1377 else if (is_migration_entry(entry)) {
1378 struct page *page;
1379
1380 page = migration_entry_to_page(entry);
1381 rss[mm_counter(page)]--;
1382 }
1383 if (unlikely(!free_swap_and_cache(entry)))
1384 print_bad_pte(vma, addr, ptent, NULL);
1385 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1386 } while (pte++, addr += PAGE_SIZE, addr != end);
1387
1388 add_mm_rss_vec(mm, rss);
1389 arch_leave_lazy_mmu_mode();
1390
1391 /* Do the actual TLB flush before dropping ptl */
1392 if (force_flush)
1393 tlb_flush_mmu_tlbonly(tlb);
1394 pte_unmap_unlock(start_pte, ptl);
1395
1396 /*
1397 * If we forced a TLB flush (either due to running out of
1398 * batch buffers or because we needed to flush dirty TLB
1399 * entries before releasing the ptl), free the batched
1400 * memory too. Restart if we didn't do everything.
1401 */
1402 if (force_flush) {
1403 force_flush = 0;
1404 tlb_flush_mmu_free(tlb);
1405 if (addr != end)
1406 goto again;
1407 }
1408
1409 return addr;
1410}
1411
1412static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1413 struct vm_area_struct *vma, pud_t *pud,
1414 unsigned long addr, unsigned long end,
1415 struct zap_details *details)
1416{
1417 pmd_t *pmd;
1418 unsigned long next;
1419
1420 pmd = pmd_offset(pud, addr);
1421 do {
1422 next = pmd_addr_end(addr, end);
1423 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1424 if (next - addr != HPAGE_PMD_SIZE) {
1425 VM_BUG_ON_VMA(vma_is_anonymous(vma) &&
1426 !rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1427 __split_huge_pmd(vma, pmd, addr, false, NULL);
1428 } else if (zap_huge_pmd(tlb, vma, pmd, addr))
1429 goto next;
1430 /* fall through */
1431 }
1432 /*
1433 * Here there can be other concurrent MADV_DONTNEED or
1434 * trans huge page faults running, and if the pmd is
1435 * none or trans huge it can change under us. This is
1436 * because MADV_DONTNEED holds the mmap_sem in read
1437 * mode.
1438 */
1439 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1440 goto next;
1441 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1442next:
1443 cond_resched();
1444 } while (pmd++, addr = next, addr != end);
1445
1446 return addr;
1447}
1448
1449static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1450 struct vm_area_struct *vma, p4d_t *p4d,
1451 unsigned long addr, unsigned long end,
1452 struct zap_details *details)
1453{
1454 pud_t *pud;
1455 unsigned long next;
1456
1457 pud = pud_offset(p4d, addr);
1458 do {
1459 next = pud_addr_end(addr, end);
1460 if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1461 if (next - addr != HPAGE_PUD_SIZE) {
1462 VM_BUG_ON_VMA(!rwsem_is_locked(&tlb->mm->mmap_sem), vma);
1463 split_huge_pud(vma, pud, addr);
1464 } else if (zap_huge_pud(tlb, vma, pud, addr))
1465 goto next;
1466 /* fall through */
1467 }
1468 if (pud_none_or_clear_bad(pud))
1469 continue;
1470 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1471next:
1472 cond_resched();
1473 } while (pud++, addr = next, addr != end);
1474
1475 return addr;
1476}
1477
1478static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
1479 struct vm_area_struct *vma, pgd_t *pgd,
1480 unsigned long addr, unsigned long end,
1481 struct zap_details *details)
1482{
1483 p4d_t *p4d;
1484 unsigned long next;
1485
1486 p4d = p4d_offset(pgd, addr);
1487 do {
1488 next = p4d_addr_end(addr, end);
1489 if (p4d_none_or_clear_bad(p4d))
1490 continue;
1491 next = zap_pud_range(tlb, vma, p4d, addr, next, details);
1492 } while (p4d++, addr = next, addr != end);
1493
1494 return addr;
1495}
1496
1497void unmap_page_range(struct mmu_gather *tlb,
1498 struct vm_area_struct *vma,
1499 unsigned long addr, unsigned long end,
1500 struct zap_details *details)
1501{
1502 pgd_t *pgd;
1503 unsigned long next;
1504
1505 BUG_ON(addr >= end);
1506 tlb_start_vma(tlb, vma);
1507 pgd = pgd_offset(vma->vm_mm, addr);
1508 do {
1509 next = pgd_addr_end(addr, end);
1510 if (pgd_none_or_clear_bad(pgd))
1511 continue;
1512 next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
1513 } while (pgd++, addr = next, addr != end);
1514 tlb_end_vma(tlb, vma);
1515}
1516
1517
1518static void unmap_single_vma(struct mmu_gather *tlb,
1519 struct vm_area_struct *vma, unsigned long start_addr,
1520 unsigned long end_addr,
1521 struct zap_details *details)
1522{
1523 unsigned long start = max(vma->vm_start, start_addr);
1524 unsigned long end;
1525
1526 if (start >= vma->vm_end)
1527 return;
1528 end = min(vma->vm_end, end_addr);
1529 if (end <= vma->vm_start)
1530 return;
1531
1532 if (vma->vm_file)
1533 uprobe_munmap(vma, start, end);
1534
1535 if (unlikely(vma->vm_flags & VM_PFNMAP))
1536 untrack_pfn(vma, 0, 0);
1537
1538 if (start != end) {
1539 if (unlikely(is_vm_hugetlb_page(vma))) {
1540 /*
1541 * It is undesirable to test vma->vm_file as it
1542 * should be non-null for valid hugetlb area.
1543 * However, vm_file will be NULL in the error
1544 * cleanup path of mmap_region. When
1545 * hugetlbfs ->mmap method fails,
1546 * mmap_region() nullifies vma->vm_file
1547 * before calling this function to clean up.
1548 * Since no pte has actually been setup, it is
1549 * safe to do nothing in this case.
1550 */
1551 if (vma->vm_file) {
1552 i_mmap_lock_write(vma->vm_file->f_mapping);
1553 __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1554 i_mmap_unlock_write(vma->vm_file->f_mapping);
1555 }
1556 } else
1557 unmap_page_range(tlb, vma, start, end, details);
1558 }
1559}
1560
1561/**
1562 * unmap_vmas - unmap a range of memory covered by a list of vma's
1563 * @tlb: address of the caller's struct mmu_gather
1564 * @vma: the starting vma
1565 * @start_addr: virtual address at which to start unmapping
1566 * @end_addr: virtual address at which to end unmapping
1567 *
1568 * Unmap all pages in the vma list.
1569 *
1570 * Only addresses between `start' and `end' will be unmapped.
1571 *
1572 * The VMA list must be sorted in ascending virtual address order.
1573 *
1574 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1575 * range after unmap_vmas() returns. So the only responsibility here is to
1576 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1577 * drops the lock and schedules.
1578 */
1579void unmap_vmas(struct mmu_gather *tlb,
1580 struct vm_area_struct *vma, unsigned long start_addr,
1581 unsigned long end_addr)
1582{
1583 struct mm_struct *mm = vma->vm_mm;
1584
1585 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1586 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1587 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1588 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1589}
1590
1591/**
1592 * zap_page_range - remove user pages in a given range
1593 * @vma: vm_area_struct holding the applicable pages
1594 * @start: starting address of pages to zap
1595 * @size: number of bytes to zap
1596 *
1597 * Caller must protect the VMA list
1598 */
1599void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1600 unsigned long size)
1601{
1602 struct mm_struct *mm = vma->vm_mm;
1603 struct mmu_gather tlb;
1604 unsigned long end = start + size;
1605
1606 lru_add_drain();
1607 tlb_gather_mmu(&tlb, mm, start, end);
1608 update_hiwater_rss(mm);
1609 mmu_notifier_invalidate_range_start(mm, start, end);
1610 for ( ; vma && vma->vm_start < end; vma = vma->vm_next) {
1611 unmap_single_vma(&tlb, vma, start, end, NULL);
1612
1613 /*
1614 * zap_page_range does not specify whether mmap_sem should be
1615 * held for read or write. That allows parallel zap_page_range
1616 * operations to unmap a PTE and defer a flush meaning that
1617 * this call observes pte_none and fails to flush the TLB.
1618 * Rather than adding a complex API, ensure that no stale
1619 * TLB entries exist when this call returns.
1620 */
1621 flush_tlb_range(vma, start, end);
1622 }
1623
1624 mmu_notifier_invalidate_range_end(mm, start, end);
1625 tlb_finish_mmu(&tlb, start, end);
1626}
1627
1628/**
1629 * zap_page_range_single - remove user pages in a given range
1630 * @vma: vm_area_struct holding the applicable pages
1631 * @address: starting address of pages to zap
1632 * @size: number of bytes to zap
1633 * @details: details of shared cache invalidation
1634 *
1635 * The range must fit into one VMA.
1636 */
1637static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1638 unsigned long size, struct zap_details *details)
1639{
1640 struct mm_struct *mm = vma->vm_mm;
1641 struct mmu_gather tlb;
1642 unsigned long end = address + size;
1643
1644 lru_add_drain();
1645 tlb_gather_mmu(&tlb, mm, address, end);
1646 update_hiwater_rss(mm);
1647 mmu_notifier_invalidate_range_start(mm, address, end);
1648 unmap_single_vma(&tlb, vma, address, end, details);
1649 mmu_notifier_invalidate_range_end(mm, address, end);
1650 tlb_finish_mmu(&tlb, address, end);
1651}
1652
1653/**
1654 * zap_vma_ptes - remove ptes mapping the vma
1655 * @vma: vm_area_struct holding ptes to be zapped
1656 * @address: starting address of pages to zap
1657 * @size: number of bytes to zap
1658 *
1659 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1660 *
1661 * The entire address range must be fully contained within the vma.
1662 *
1663 * Returns 0 if successful.
1664 */
1665int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1666 unsigned long size)
1667{
1668 if (address < vma->vm_start || address + size > vma->vm_end ||
1669 !(vma->vm_flags & VM_PFNMAP))
1670 return -1;
1671 zap_page_range_single(vma, address, size, NULL);
1672 return 0;
1673}
1674EXPORT_SYMBOL_GPL(zap_vma_ptes);
1675
1676pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
1677 spinlock_t **ptl)
1678{
1679 pgd_t *pgd;
1680 p4d_t *p4d;
1681 pud_t *pud;
1682 pmd_t *pmd;
1683
1684 pgd = pgd_offset(mm, addr);
1685 p4d = p4d_alloc(mm, pgd, addr);
1686 if (!p4d)
1687 return NULL;
1688 pud = pud_alloc(mm, p4d, addr);
1689 if (!pud)
1690 return NULL;
1691 pmd = pmd_alloc(mm, pud, addr);
1692 if (!pmd)
1693 return NULL;
1694
1695 VM_BUG_ON(pmd_trans_huge(*pmd));
1696 return pte_alloc_map_lock(mm, pmd, addr, ptl);
1697}
1698
1699/*
1700 * This is the old fallback for page remapping.
1701 *
1702 * For historical reasons, it only allows reserved pages. Only
1703 * old drivers should use this, and they needed to mark their
1704 * pages reserved for the old functions anyway.
1705 */
1706static int insert_page(struct vm_area_struct *vma, unsigned long addr,
1707 struct page *page, pgprot_t prot)
1708{
1709 struct mm_struct *mm = vma->vm_mm;
1710 int retval;
1711 pte_t *pte;
1712 spinlock_t *ptl;
1713
1714 retval = -EINVAL;
1715 if (PageAnon(page))
1716 goto out;
1717 retval = -ENOMEM;
1718 flush_dcache_page(page);
1719 pte = get_locked_pte(mm, addr, &ptl);
1720 if (!pte)
1721 goto out;
1722 retval = -EBUSY;
1723 if (!pte_none(*pte))
1724 goto out_unlock;
1725
1726 /* Ok, finally just insert the thing.. */
1727 get_page(page);
1728 inc_mm_counter_fast(mm, mm_counter_file(page));
1729 page_add_file_rmap(page, false);
1730 set_pte_at(mm, addr, pte, mk_pte(page, prot));
1731
1732 retval = 0;
1733 pte_unmap_unlock(pte, ptl);
1734 return retval;
1735out_unlock:
1736 pte_unmap_unlock(pte, ptl);
1737out:
1738 return retval;
1739}
1740
1741/**
1742 * vm_insert_page - insert single page into user vma
1743 * @vma: user vma to map to
1744 * @addr: target user address of this page
1745 * @page: source kernel page
1746 *
1747 * This allows drivers to insert individual pages they've allocated
1748 * into a user vma.
1749 *
1750 * The page has to be a nice clean _individual_ kernel allocation.
1751 * If you allocate a compound page, you need to have marked it as
1752 * such (__GFP_COMP), or manually just split the page up yourself
1753 * (see split_page()).
1754 *
1755 * NOTE! Traditionally this was done with "remap_pfn_range()" which
1756 * took an arbitrary page protection parameter. This doesn't allow
1757 * that. Your vma protection will have to be set up correctly, which
1758 * means that if you want a shared writable mapping, you'd better
1759 * ask for a shared writable mapping!
1760 *
1761 * The page does not need to be reserved.
1762 *
1763 * Usually this function is called from f_op->mmap() handler
1764 * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
1765 * Caller must set VM_MIXEDMAP on vma if it wants to call this
1766 * function from other places, for example from page-fault handler.
1767 */
1768int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
1769 struct page *page)
1770{
1771 if (addr < vma->vm_start || addr >= vma->vm_end)
1772 return -EFAULT;
1773 if (!page_count(page))
1774 return -EINVAL;
1775 if (!(vma->vm_flags & VM_MIXEDMAP)) {
1776 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
1777 BUG_ON(vma->vm_flags & VM_PFNMAP);
1778 vma->vm_flags |= VM_MIXEDMAP;
1779 }
1780 return insert_page(vma, addr, page, vma->vm_page_prot);
1781}
1782EXPORT_SYMBOL(vm_insert_page);
1783
1784static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1785 pfn_t pfn, pgprot_t prot, bool mkwrite)
1786{
1787 struct mm_struct *mm = vma->vm_mm;
1788 int retval;
1789 pte_t *pte, entry;
1790 spinlock_t *ptl;
1791
1792 retval = -ENOMEM;
1793 pte = get_locked_pte(mm, addr, &ptl);
1794 if (!pte)
1795 goto out;
1796 retval = -EBUSY;
1797 if (!pte_none(*pte)) {
1798 if (mkwrite) {
1799 /*
1800 * For read faults on private mappings the PFN passed
1801 * in may not match the PFN we have mapped if the
1802 * mapped PFN is a writeable COW page. In the mkwrite
1803 * case we are creating a writable PTE for a shared
1804 * mapping and we expect the PFNs to match.
1805 */
1806 if (WARN_ON_ONCE(pte_pfn(*pte) != pfn_t_to_pfn(pfn)))
1807 goto out_unlock;
1808 entry = *pte;
1809 goto out_mkwrite;
1810 } else
1811 goto out_unlock;
1812 }
1813
1814 /* Ok, finally just insert the thing.. */
1815 if (pfn_t_devmap(pfn))
1816 entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
1817 else
1818 entry = pte_mkspecial(pfn_t_pte(pfn, prot));
1819
1820out_mkwrite:
1821 if (mkwrite) {
1822 entry = pte_mkyoung(entry);
1823 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
1824 }
1825
1826 set_pte_at(mm, addr, pte, entry);
1827 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
1828
1829 retval = 0;
1830out_unlock:
1831 pte_unmap_unlock(pte, ptl);
1832out:
1833 return retval;
1834}
1835
1836/**
1837 * vm_insert_pfn - insert single pfn into user vma
1838 * @vma: user vma to map to
1839 * @addr: target user address of this page
1840 * @pfn: source kernel pfn
1841 *
1842 * Similar to vm_insert_page, this allows drivers to insert individual pages
1843 * they've allocated into a user vma. Same comments apply.
1844 *
1845 * This function should only be called from a vm_ops->fault handler, and
1846 * in that case the handler should return NULL.
1847 *
1848 * vma cannot be a COW mapping.
1849 *
1850 * As this is called only for pages that do not currently exist, we
1851 * do not need to flush old virtual caches or the TLB.
1852 */
1853int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
1854 unsigned long pfn)
1855{
1856 return vm_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
1857}
1858EXPORT_SYMBOL(vm_insert_pfn);
1859
1860/**
1861 * vm_insert_pfn_prot - insert single pfn into user vma with specified pgprot
1862 * @vma: user vma to map to
1863 * @addr: target user address of this page
1864 * @pfn: source kernel pfn
1865 * @pgprot: pgprot flags for the inserted page
1866 *
1867 * This is exactly like vm_insert_pfn, except that it allows drivers to
1868 * to override pgprot on a per-page basis.
1869 *
1870 * This only makes sense for IO mappings, and it makes no sense for
1871 * cow mappings. In general, using multiple vmas is preferable;
1872 * vm_insert_pfn_prot should only be used if using multiple VMAs is
1873 * impractical.
1874 */
1875int vm_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
1876 unsigned long pfn, pgprot_t pgprot)
1877{
1878 int ret;
1879 /*
1880 * Technically, architectures with pte_special can avoid all these
1881 * restrictions (same for remap_pfn_range). However we would like
1882 * consistency in testing and feature parity among all, so we should
1883 * try to keep these invariants in place for everybody.
1884 */
1885 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
1886 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
1887 (VM_PFNMAP|VM_MIXEDMAP));
1888 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
1889 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
1890
1891 if (addr < vma->vm_start || addr >= vma->vm_end)
1892 return -EFAULT;
1893
1894 track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
1895
1896 ret = insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
1897 false);
1898
1899 return ret;
1900}
1901EXPORT_SYMBOL(vm_insert_pfn_prot);
1902
1903static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
1904{
1905 /* these checks mirror the abort conditions in vm_normal_page */
1906 if (vma->vm_flags & VM_MIXEDMAP)
1907 return true;
1908 if (pfn_t_devmap(pfn))
1909 return true;
1910 if (pfn_t_special(pfn))
1911 return true;
1912 if (is_zero_pfn(pfn_t_to_pfn(pfn)))
1913 return true;
1914 return false;
1915}
1916
1917static int __vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1918 pfn_t pfn, bool mkwrite)
1919{
1920 pgprot_t pgprot = vma->vm_page_prot;
1921
1922 BUG_ON(!vm_mixed_ok(vma, pfn));
1923
1924 if (addr < vma->vm_start || addr >= vma->vm_end)
1925 return -EFAULT;
1926
1927 track_pfn_insert(vma, &pgprot, pfn);
1928
1929 /*
1930 * If we don't have pte special, then we have to use the pfn_valid()
1931 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
1932 * refcount the page if pfn_valid is true (hence insert_page rather
1933 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
1934 * without pte special, it would there be refcounted as a normal page.
1935 */
1936 if (!HAVE_PTE_SPECIAL && !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
1937 struct page *page;
1938
1939 /*
1940 * At this point we are committed to insert_page()
1941 * regardless of whether the caller specified flags that
1942 * result in pfn_t_has_page() == false.
1943 */
1944 page = pfn_to_page(pfn_t_to_pfn(pfn));
1945 return insert_page(vma, addr, page, pgprot);
1946 }
1947 return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
1948}
1949
1950int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
1951 pfn_t pfn)
1952{
1953 return __vm_insert_mixed(vma, addr, pfn, false);
1954
1955}
1956EXPORT_SYMBOL(vm_insert_mixed);
1957
1958int vm_insert_mixed_mkwrite(struct vm_area_struct *vma, unsigned long addr,
1959 pfn_t pfn)
1960{
1961 return __vm_insert_mixed(vma, addr, pfn, true);
1962}
1963EXPORT_SYMBOL(vm_insert_mixed_mkwrite);
1964
1965/*
1966 * maps a range of physical memory into the requested pages. the old
1967 * mappings are removed. any references to nonexistent pages results
1968 * in null mappings (currently treated as "copy-on-access")
1969 */
1970static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
1971 unsigned long addr, unsigned long end,
1972 unsigned long pfn, pgprot_t prot)
1973{
1974 pte_t *pte;
1975 spinlock_t *ptl;
1976
1977 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
1978 if (!pte)
1979 return -ENOMEM;
1980 arch_enter_lazy_mmu_mode();
1981 do {
1982 BUG_ON(!pte_none(*pte));
1983 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
1984 pfn++;
1985 } while (pte++, addr += PAGE_SIZE, addr != end);
1986 arch_leave_lazy_mmu_mode();
1987 pte_unmap_unlock(pte - 1, ptl);
1988 return 0;
1989}
1990
1991static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
1992 unsigned long addr, unsigned long end,
1993 unsigned long pfn, pgprot_t prot)
1994{
1995 pmd_t *pmd;
1996 unsigned long next;
1997
1998 pfn -= addr >> PAGE_SHIFT;
1999 pmd = pmd_alloc(mm, pud, addr);
2000 if (!pmd)
2001 return -ENOMEM;
2002 VM_BUG_ON(pmd_trans_huge(*pmd));
2003 do {
2004 next = pmd_addr_end(addr, end);
2005 if (remap_pte_range(mm, pmd, addr, next,
2006 pfn + (addr >> PAGE_SHIFT), prot))
2007 return -ENOMEM;
2008 } while (pmd++, addr = next, addr != end);
2009 return 0;
2010}
2011
2012static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
2013 unsigned long addr, unsigned long end,
2014 unsigned long pfn, pgprot_t prot)
2015{
2016 pud_t *pud;
2017 unsigned long next;
2018
2019 pfn -= addr >> PAGE_SHIFT;
2020 pud = pud_alloc(mm, p4d, addr);
2021 if (!pud)
2022 return -ENOMEM;
2023 do {
2024 next = pud_addr_end(addr, end);
2025 if (remap_pmd_range(mm, pud, addr, next,
2026 pfn + (addr >> PAGE_SHIFT), prot))
2027 return -ENOMEM;
2028 } while (pud++, addr = next, addr != end);
2029 return 0;
2030}
2031
2032static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2033 unsigned long addr, unsigned long end,
2034 unsigned long pfn, pgprot_t prot)
2035{
2036 p4d_t *p4d;
2037 unsigned long next;
2038
2039 pfn -= addr >> PAGE_SHIFT;
2040 p4d = p4d_alloc(mm, pgd, addr);
2041 if (!p4d)
2042 return -ENOMEM;
2043 do {
2044 next = p4d_addr_end(addr, end);
2045 if (remap_pud_range(mm, p4d, addr, next,
2046 pfn + (addr >> PAGE_SHIFT), prot))
2047 return -ENOMEM;
2048 } while (p4d++, addr = next, addr != end);
2049 return 0;
2050}
2051
2052/**
2053 * remap_pfn_range - remap kernel memory to userspace
2054 * @vma: user vma to map to
2055 * @addr: target user address to start at
2056 * @pfn: physical address of kernel memory
2057 * @size: size of map area
2058 * @prot: page protection flags for this mapping
2059 *
2060 * Note: this is only safe if the mm semaphore is held when called.
2061 */
2062int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2063 unsigned long pfn, unsigned long size, pgprot_t prot)
2064{
2065 pgd_t *pgd;
2066 unsigned long next;
2067 unsigned long end = addr + PAGE_ALIGN(size);
2068 struct mm_struct *mm = vma->vm_mm;
2069 unsigned long remap_pfn = pfn;
2070 int err;
2071
2072 /*
2073 * Physically remapped pages are special. Tell the
2074 * rest of the world about it:
2075 * VM_IO tells people not to look at these pages
2076 * (accesses can have side effects).
2077 * VM_PFNMAP tells the core MM that the base pages are just
2078 * raw PFN mappings, and do not have a "struct page" associated
2079 * with them.
2080 * VM_DONTEXPAND
2081 * Disable vma merging and expanding with mremap().
2082 * VM_DONTDUMP
2083 * Omit vma from core dump, even when VM_IO turned off.
2084 *
2085 * There's a horrible special case to handle copy-on-write
2086 * behaviour that some programs depend on. We mark the "original"
2087 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2088 * See vm_normal_page() for details.
2089 */
2090 if (is_cow_mapping(vma->vm_flags)) {
2091 if (addr != vma->vm_start || end != vma->vm_end)
2092 return -EINVAL;
2093 vma->vm_pgoff = pfn;
2094 }
2095
2096 err = track_pfn_remap(vma, &prot, remap_pfn, addr, PAGE_ALIGN(size));
2097 if (err)
2098 return -EINVAL;
2099
2100 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
2101
2102 BUG_ON(addr >= end);
2103 pfn -= addr >> PAGE_SHIFT;
2104 pgd = pgd_offset(mm, addr);
2105 flush_cache_range(vma, addr, end);
2106 do {
2107 next = pgd_addr_end(addr, end);
2108 err = remap_p4d_range(mm, pgd, addr, next,
2109 pfn + (addr >> PAGE_SHIFT), prot);
2110 if (err)
2111 break;
2112 } while (pgd++, addr = next, addr != end);
2113
2114 if (err)
2115 untrack_pfn(vma, remap_pfn, PAGE_ALIGN(size));
2116
2117 return err;
2118}
2119EXPORT_SYMBOL(remap_pfn_range);
2120
2121/**
2122 * vm_iomap_memory - remap memory to userspace
2123 * @vma: user vma to map to
2124 * @start: start of area
2125 * @len: size of area
2126 *
2127 * This is a simplified io_remap_pfn_range() for common driver use. The
2128 * driver just needs to give us the physical memory range to be mapped,
2129 * we'll figure out the rest from the vma information.
2130 *
2131 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2132 * whatever write-combining details or similar.
2133 */
2134int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2135{
2136 unsigned long vm_len, pfn, pages;
2137
2138 /* Check that the physical memory area passed in looks valid */
2139 if (start + len < start)
2140 return -EINVAL;
2141 /*
2142 * You *really* shouldn't map things that aren't page-aligned,
2143 * but we've historically allowed it because IO memory might
2144 * just have smaller alignment.
2145 */
2146 len += start & ~PAGE_MASK;
2147 pfn = start >> PAGE_SHIFT;
2148 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2149 if (pfn + pages < pfn)
2150 return -EINVAL;
2151
2152 /* We start the mapping 'vm_pgoff' pages into the area */
2153 if (vma->vm_pgoff > pages)
2154 return -EINVAL;
2155 pfn += vma->vm_pgoff;
2156 pages -= vma->vm_pgoff;
2157
2158 /* Can we fit all of the mapping? */
2159 vm_len = vma->vm_end - vma->vm_start;
2160 if (vm_len >> PAGE_SHIFT > pages)
2161 return -EINVAL;
2162
2163 /* Ok, let it rip */
2164 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2165}
2166EXPORT_SYMBOL(vm_iomap_memory);
2167
2168static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2169 unsigned long addr, unsigned long end,
2170 pte_fn_t fn, void *data)
2171{
2172 pte_t *pte;
2173 int err;
2174 pgtable_t token;
2175 spinlock_t *uninitialized_var(ptl);
2176
2177 pte = (mm == &init_mm) ?
2178 pte_alloc_kernel(pmd, addr) :
2179 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2180 if (!pte)
2181 return -ENOMEM;
2182
2183 BUG_ON(pmd_huge(*pmd));
2184
2185 arch_enter_lazy_mmu_mode();
2186
2187 token = pmd_pgtable(*pmd);
2188
2189 do {
2190 err = fn(pte++, token, addr, data);
2191 if (err)
2192 break;
2193 } while (addr += PAGE_SIZE, addr != end);
2194
2195 arch_leave_lazy_mmu_mode();
2196
2197 if (mm != &init_mm)
2198 pte_unmap_unlock(pte-1, ptl);
2199 return err;
2200}
2201
2202static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2203 unsigned long addr, unsigned long end,
2204 pte_fn_t fn, void *data)
2205{
2206 pmd_t *pmd;
2207 unsigned long next;
2208 int err;
2209
2210 BUG_ON(pud_huge(*pud));
2211
2212 pmd = pmd_alloc(mm, pud, addr);
2213 if (!pmd)
2214 return -ENOMEM;
2215 do {
2216 next = pmd_addr_end(addr, end);
2217 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2218 if (err)
2219 break;
2220 } while (pmd++, addr = next, addr != end);
2221 return err;
2222}
2223
2224static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
2225 unsigned long addr, unsigned long end,
2226 pte_fn_t fn, void *data)
2227{
2228 pud_t *pud;
2229 unsigned long next;
2230 int err;
2231
2232 pud = pud_alloc(mm, p4d, addr);
2233 if (!pud)
2234 return -ENOMEM;
2235 do {
2236 next = pud_addr_end(addr, end);
2237 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2238 if (err)
2239 break;
2240 } while (pud++, addr = next, addr != end);
2241 return err;
2242}
2243
2244static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2245 unsigned long addr, unsigned long end,
2246 pte_fn_t fn, void *data)
2247{
2248 p4d_t *p4d;
2249 unsigned long next;
2250 int err;
2251
2252 p4d = p4d_alloc(mm, pgd, addr);
2253 if (!p4d)
2254 return -ENOMEM;
2255 do {
2256 next = p4d_addr_end(addr, end);
2257 err = apply_to_pud_range(mm, p4d, addr, next, fn, data);
2258 if (err)
2259 break;
2260 } while (p4d++, addr = next, addr != end);
2261 return err;
2262}
2263
2264/*
2265 * Scan a region of virtual memory, filling in page tables as necessary
2266 * and calling a provided function on each leaf page table.
2267 */
2268int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2269 unsigned long size, pte_fn_t fn, void *data)
2270{
2271 pgd_t *pgd;
2272 unsigned long next;
2273 unsigned long end = addr + size;
2274 int err;
2275
2276 if (WARN_ON(addr >= end))
2277 return -EINVAL;
2278
2279 pgd = pgd_offset(mm, addr);
2280 do {
2281 next = pgd_addr_end(addr, end);
2282 err = apply_to_p4d_range(mm, pgd, addr, next, fn, data);
2283 if (err)
2284 break;
2285 } while (pgd++, addr = next, addr != end);
2286
2287 return err;
2288}
2289EXPORT_SYMBOL_GPL(apply_to_page_range);
2290
2291/*
2292 * handle_pte_fault chooses page fault handler according to an entry which was
2293 * read non-atomically. Before making any commitment, on those architectures
2294 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
2295 * parts, do_swap_page must check under lock before unmapping the pte and
2296 * proceeding (but do_wp_page is only called after already making such a check;
2297 * and do_anonymous_page can safely check later on).
2298 */
2299static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2300 pte_t *page_table, pte_t orig_pte)
2301{
2302 int same = 1;
2303#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2304 if (sizeof(pte_t) > sizeof(unsigned long)) {
2305 spinlock_t *ptl = pte_lockptr(mm, pmd);
2306 spin_lock(ptl);
2307 same = pte_same(*page_table, orig_pte);
2308 spin_unlock(ptl);
2309 }
2310#endif
2311 pte_unmap(page_table);
2312 return same;
2313}
2314
2315static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2316{
2317 debug_dma_assert_idle(src);
2318
2319 /*
2320 * If the source page was a PFN mapping, we don't have
2321 * a "struct page" for it. We do a best-effort copy by
2322 * just copying from the original user address. If that
2323 * fails, we just zero-fill it. Live with it.
2324 */
2325 if (unlikely(!src)) {
2326 void *kaddr = kmap_atomic(dst);
2327 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2328
2329 /*
2330 * This really shouldn't fail, because the page is there
2331 * in the page tables. But it might just be unreadable,
2332 * in which case we just give up and fill the result with
2333 * zeroes.
2334 */
2335 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2336 clear_page(kaddr);
2337 kunmap_atomic(kaddr);
2338 flush_dcache_page(dst);
2339 } else
2340 copy_user_highpage(dst, src, va, vma);
2341}
2342
2343static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
2344{
2345 struct file *vm_file = vma->vm_file;
2346
2347 if (vm_file)
2348 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
2349
2350 /*
2351 * Special mappings (e.g. VDSO) do not have any file so fake
2352 * a default GFP_KERNEL for them.
2353 */
2354 return GFP_KERNEL;
2355}
2356
2357/*
2358 * Notify the address space that the page is about to become writable so that
2359 * it can prohibit this or wait for the page to get into an appropriate state.
2360 *
2361 * We do this without the lock held, so that it can sleep if it needs to.
2362 */
2363static int do_page_mkwrite(struct vm_fault *vmf)
2364{
2365 int ret;
2366 struct page *page = vmf->page;
2367 unsigned int old_flags = vmf->flags;
2368
2369 vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2370
2371 ret = vmf->vma->vm_ops->page_mkwrite(vmf);
2372 /* Restore original flags so that caller is not surprised */
2373 vmf->flags = old_flags;
2374 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2375 return ret;
2376 if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2377 lock_page(page);
2378 if (!page->mapping) {
2379 unlock_page(page);
2380 return 0; /* retry */
2381 }
2382 ret |= VM_FAULT_LOCKED;
2383 } else
2384 VM_BUG_ON_PAGE(!PageLocked(page), page);
2385 return ret;
2386}
2387
2388/*
2389 * Handle dirtying of a page in shared file mapping on a write fault.
2390 *
2391 * The function expects the page to be locked and unlocks it.
2392 */
2393static void fault_dirty_shared_page(struct vm_area_struct *vma,
2394 struct page *page)
2395{
2396 struct address_space *mapping;
2397 bool dirtied;
2398 bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
2399
2400 dirtied = set_page_dirty(page);
2401 VM_BUG_ON_PAGE(PageAnon(page), page);
2402 /*
2403 * Take a local copy of the address_space - page.mapping may be zeroed
2404 * by truncate after unlock_page(). The address_space itself remains
2405 * pinned by vma->vm_file's reference. We rely on unlock_page()'s
2406 * release semantics to prevent the compiler from undoing this copying.
2407 */
2408 mapping = page_rmapping(page);
2409 unlock_page(page);
2410
2411 if ((dirtied || page_mkwrite) && mapping) {
2412 /*
2413 * Some device drivers do not set page.mapping
2414 * but still dirty their pages
2415 */
2416 balance_dirty_pages_ratelimited(mapping);
2417 }
2418
2419 if (!page_mkwrite)
2420 file_update_time(vma->vm_file);
2421}
2422
2423/*
2424 * Handle write page faults for pages that can be reused in the current vma
2425 *
2426 * This can happen either due to the mapping being with the VM_SHARED flag,
2427 * or due to us being the last reference standing to the page. In either
2428 * case, all we need to do here is to mark the page as writable and update
2429 * any related book-keeping.
2430 */
2431static inline void wp_page_reuse(struct vm_fault *vmf)
2432 __releases(vmf->ptl)
2433{
2434 struct vm_area_struct *vma = vmf->vma;
2435 struct page *page = vmf->page;
2436 pte_t entry;
2437 /*
2438 * Clear the pages cpupid information as the existing
2439 * information potentially belongs to a now completely
2440 * unrelated process.
2441 */
2442 if (page)
2443 page_cpupid_xchg_last(page, (1 << LAST_CPUPID_SHIFT) - 1);
2444
2445 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2446 entry = pte_mkyoung(vmf->orig_pte);
2447 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2448 if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
2449 update_mmu_cache(vma, vmf->address, vmf->pte);
2450 pte_unmap_unlock(vmf->pte, vmf->ptl);
2451}
2452
2453/*
2454 * Handle the case of a page which we actually need to copy to a new page.
2455 *
2456 * Called with mmap_sem locked and the old page referenced, but
2457 * without the ptl held.
2458 *
2459 * High level logic flow:
2460 *
2461 * - Allocate a page, copy the content of the old page to the new one.
2462 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
2463 * - Take the PTL. If the pte changed, bail out and release the allocated page
2464 * - If the pte is still the way we remember it, update the page table and all
2465 * relevant references. This includes dropping the reference the page-table
2466 * held to the old page, as well as updating the rmap.
2467 * - In any case, unlock the PTL and drop the reference we took to the old page.
2468 */
2469static int wp_page_copy(struct vm_fault *vmf)
2470{
2471 struct vm_area_struct *vma = vmf->vma;
2472 struct mm_struct *mm = vma->vm_mm;
2473 struct page *old_page = vmf->page;
2474 struct page *new_page = NULL;
2475 pte_t entry;
2476 int page_copied = 0;
2477 const unsigned long mmun_start = vmf->address & PAGE_MASK;
2478 const unsigned long mmun_end = mmun_start + PAGE_SIZE;
2479 struct mem_cgroup *memcg;
2480
2481 if (unlikely(anon_vma_prepare(vma)))
2482 goto oom;
2483
2484 if (is_zero_pfn(pte_pfn(vmf->orig_pte))) {
2485 new_page = alloc_zeroed_user_highpage_movable(vma,
2486 vmf->address);
2487 if (!new_page)
2488 goto oom;
2489 } else {
2490 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
2491 vmf->address);
2492 if (!new_page)
2493 goto oom;
2494 cow_user_page(new_page, old_page, vmf->address, vma);
2495 }
2496
2497 if (mem_cgroup_try_charge(new_page, mm, GFP_KERNEL, &memcg, false))
2498 goto oom_free_new;
2499
2500 __SetPageUptodate(new_page);
2501
2502 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2503
2504 /*
2505 * Re-check the pte - we dropped the lock
2506 */
2507 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
2508 if (likely(pte_same(*vmf->pte, vmf->orig_pte))) {
2509 if (old_page) {
2510 if (!PageAnon(old_page)) {
2511 dec_mm_counter_fast(mm,
2512 mm_counter_file(old_page));
2513 inc_mm_counter_fast(mm, MM_ANONPAGES);
2514 }
2515 } else {
2516 inc_mm_counter_fast(mm, MM_ANONPAGES);
2517 }
2518 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
2519 entry = mk_pte(new_page, vma->vm_page_prot);
2520 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2521 /*
2522 * Clear the pte entry and flush it first, before updating the
2523 * pte with the new entry. This will avoid a race condition
2524 * seen in the presence of one thread doing SMC and another
2525 * thread doing COW.
2526 */
2527 ptep_clear_flush_notify(vma, vmf->address, vmf->pte);
2528 page_add_new_anon_rmap(new_page, vma, vmf->address, false);
2529 mem_cgroup_commit_charge(new_page, memcg, false, false);
2530 lru_cache_add_active_or_unevictable(new_page, vma);
2531 /*
2532 * We call the notify macro here because, when using secondary
2533 * mmu page tables (such as kvm shadow page tables), we want the
2534 * new page to be mapped directly into the secondary page table.
2535 */
2536 set_pte_at_notify(mm, vmf->address, vmf->pte, entry);
2537 update_mmu_cache(vma, vmf->address, vmf->pte);
2538 if (old_page) {
2539 /*
2540 * Only after switching the pte to the new page may
2541 * we remove the mapcount here. Otherwise another
2542 * process may come and find the rmap count decremented
2543 * before the pte is switched to the new page, and
2544 * "reuse" the old page writing into it while our pte
2545 * here still points into it and can be read by other
2546 * threads.
2547 *
2548 * The critical issue is to order this
2549 * page_remove_rmap with the ptp_clear_flush above.
2550 * Those stores are ordered by (if nothing else,)
2551 * the barrier present in the atomic_add_negative
2552 * in page_remove_rmap.
2553 *
2554 * Then the TLB flush in ptep_clear_flush ensures that
2555 * no process can access the old page before the
2556 * decremented mapcount is visible. And the old page
2557 * cannot be reused until after the decremented
2558 * mapcount is visible. So transitively, TLBs to
2559 * old page will be flushed before it can be reused.
2560 */
2561 page_remove_rmap(old_page, false);
2562 }
2563
2564 /* Free the old page.. */
2565 new_page = old_page;
2566 page_copied = 1;
2567 } else {
2568 mem_cgroup_cancel_charge(new_page, memcg, false);
2569 }
2570
2571 if (new_page)
2572 put_page(new_page);
2573
2574 pte_unmap_unlock(vmf->pte, vmf->ptl);
2575 /*
2576 * No need to double call mmu_notifier->invalidate_range() callback as
2577 * the above ptep_clear_flush_notify() did already call it.
2578 */
2579 mmu_notifier_invalidate_range_only_end(mm, mmun_start, mmun_end);
2580 if (old_page) {
2581 /*
2582 * Don't let another task, with possibly unlocked vma,
2583 * keep the mlocked page.
2584 */
2585 if (page_copied && (vma->vm_flags & VM_LOCKED)) {
2586 lock_page(old_page); /* LRU manipulation */
2587 if (PageMlocked(old_page))
2588 munlock_vma_page(old_page);
2589 unlock_page(old_page);
2590 }
2591 put_page(old_page);
2592 }
2593 return page_copied ? VM_FAULT_WRITE : 0;
2594oom_free_new:
2595 put_page(new_page);
2596oom:
2597 if (old_page)
2598 put_page(old_page);
2599 return VM_FAULT_OOM;
2600}
2601
2602/**
2603 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
2604 * writeable once the page is prepared
2605 *
2606 * @vmf: structure describing the fault
2607 *
2608 * This function handles all that is needed to finish a write page fault in a
2609 * shared mapping due to PTE being read-only once the mapped page is prepared.
2610 * It handles locking of PTE and modifying it. The function returns
2611 * VM_FAULT_WRITE on success, 0 when PTE got changed before we acquired PTE
2612 * lock.
2613 *
2614 * The function expects the page to be locked or other protection against
2615 * concurrent faults / writeback (such as DAX radix tree locks).
2616 */
2617int finish_mkwrite_fault(struct vm_fault *vmf)
2618{
2619 WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
2620 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
2621 &vmf->ptl);
2622 /*
2623 * We might have raced with another page fault while we released the
2624 * pte_offset_map_lock.
2625 */
2626 if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2627 pte_unmap_unlock(vmf->pte, vmf->ptl);
2628 return VM_FAULT_NOPAGE;
2629 }
2630 wp_page_reuse(vmf);
2631 return 0;
2632}
2633
2634/*
2635 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
2636 * mapping
2637 */
2638static int wp_pfn_shared(struct vm_fault *vmf)
2639{
2640 struct vm_area_struct *vma = vmf->vma;
2641
2642 if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
2643 int ret;
2644
2645 pte_unmap_unlock(vmf->pte, vmf->ptl);
2646 vmf->flags |= FAULT_FLAG_MKWRITE;
2647 ret = vma->vm_ops->pfn_mkwrite(vmf);
2648 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
2649 return ret;
2650 return finish_mkwrite_fault(vmf);
2651 }
2652 wp_page_reuse(vmf);
2653 return VM_FAULT_WRITE;
2654}
2655
2656static int wp_page_shared(struct vm_fault *vmf)
2657 __releases(vmf->ptl)
2658{
2659 struct vm_area_struct *vma = vmf->vma;
2660
2661 get_page(vmf->page);
2662
2663 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2664 int tmp;
2665
2666 pte_unmap_unlock(vmf->pte, vmf->ptl);
2667 tmp = do_page_mkwrite(vmf);
2668 if (unlikely(!tmp || (tmp &
2669 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2670 put_page(vmf->page);
2671 return tmp;
2672 }
2673 tmp = finish_mkwrite_fault(vmf);
2674 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
2675 unlock_page(vmf->page);
2676 put_page(vmf->page);
2677 return tmp;
2678 }
2679 } else {
2680 wp_page_reuse(vmf);
2681 lock_page(vmf->page);
2682 }
2683 fault_dirty_shared_page(vma, vmf->page);
2684 put_page(vmf->page);
2685
2686 return VM_FAULT_WRITE;
2687}
2688
2689/*
2690 * This routine handles present pages, when users try to write
2691 * to a shared page. It is done by copying the page to a new address
2692 * and decrementing the shared-page counter for the old page.
2693 *
2694 * Note that this routine assumes that the protection checks have been
2695 * done by the caller (the low-level page fault routine in most cases).
2696 * Thus we can safely just mark it writable once we've done any necessary
2697 * COW.
2698 *
2699 * We also mark the page dirty at this point even though the page will
2700 * change only once the write actually happens. This avoids a few races,
2701 * and potentially makes it more efficient.
2702 *
2703 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2704 * but allow concurrent faults), with pte both mapped and locked.
2705 * We return with mmap_sem still held, but pte unmapped and unlocked.
2706 */
2707static int do_wp_page(struct vm_fault *vmf)
2708 __releases(vmf->ptl)
2709{
2710 struct vm_area_struct *vma = vmf->vma;
2711
2712 vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
2713 if (!vmf->page) {
2714 /*
2715 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
2716 * VM_PFNMAP VMA.
2717 *
2718 * We should not cow pages in a shared writeable mapping.
2719 * Just mark the pages writable and/or call ops->pfn_mkwrite.
2720 */
2721 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2722 (VM_WRITE|VM_SHARED))
2723 return wp_pfn_shared(vmf);
2724
2725 pte_unmap_unlock(vmf->pte, vmf->ptl);
2726 return wp_page_copy(vmf);
2727 }
2728
2729 /*
2730 * Take out anonymous pages first, anonymous shared vmas are
2731 * not dirty accountable.
2732 */
2733 if (PageAnon(vmf->page) && !PageKsm(vmf->page)) {
2734 int total_map_swapcount;
2735 if (!trylock_page(vmf->page)) {
2736 get_page(vmf->page);
2737 pte_unmap_unlock(vmf->pte, vmf->ptl);
2738 lock_page(vmf->page);
2739 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2740 vmf->address, &vmf->ptl);
2741 if (!pte_same(*vmf->pte, vmf->orig_pte)) {
2742 unlock_page(vmf->page);
2743 pte_unmap_unlock(vmf->pte, vmf->ptl);
2744 put_page(vmf->page);
2745 return 0;
2746 }
2747 put_page(vmf->page);
2748 }
2749 if (reuse_swap_page(vmf->page, &total_map_swapcount)) {
2750 if (total_map_swapcount == 1) {
2751 /*
2752 * The page is all ours. Move it to
2753 * our anon_vma so the rmap code will
2754 * not search our parent or siblings.
2755 * Protected against the rmap code by
2756 * the page lock.
2757 */
2758 page_move_anon_rmap(vmf->page, vma);
2759 }
2760 unlock_page(vmf->page);
2761 wp_page_reuse(vmf);
2762 return VM_FAULT_WRITE;
2763 }
2764 unlock_page(vmf->page);
2765 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2766 (VM_WRITE|VM_SHARED))) {
2767 return wp_page_shared(vmf);
2768 }
2769
2770 /*
2771 * Ok, we need to copy. Oh, well..
2772 */
2773 get_page(vmf->page);
2774
2775 pte_unmap_unlock(vmf->pte, vmf->ptl);
2776 return wp_page_copy(vmf);
2777}
2778
2779static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2780 unsigned long start_addr, unsigned long end_addr,
2781 struct zap_details *details)
2782{
2783 zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2784}
2785
2786static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
2787 struct zap_details *details)
2788{
2789 struct vm_area_struct *vma;
2790 pgoff_t vba, vea, zba, zea;
2791
2792 vma_interval_tree_foreach(vma, root,
2793 details->first_index, details->last_index) {
2794
2795 vba = vma->vm_pgoff;
2796 vea = vba + vma_pages(vma) - 1;
2797 zba = details->first_index;
2798 if (zba < vba)
2799 zba = vba;
2800 zea = details->last_index;
2801 if (zea > vea)
2802 zea = vea;
2803
2804 unmap_mapping_range_vma(vma,
2805 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2806 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2807 details);
2808 }
2809}
2810
2811/**
2812 * unmap_mapping_pages() - Unmap pages from processes.
2813 * @mapping: The address space containing pages to be unmapped.
2814 * @start: Index of first page to be unmapped.
2815 * @nr: Number of pages to be unmapped. 0 to unmap to end of file.
2816 * @even_cows: Whether to unmap even private COWed pages.
2817 *
2818 * Unmap the pages in this address space from any userspace process which
2819 * has them mmaped. Generally, you want to remove COWed pages as well when
2820 * a file is being truncated, but not when invalidating pages from the page
2821 * cache.
2822 */
2823void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
2824 pgoff_t nr, bool even_cows)
2825{
2826 struct zap_details details = { };
2827
2828 details.check_mapping = even_cows ? NULL : mapping;
2829 details.first_index = start;
2830 details.last_index = start + nr - 1;
2831 if (details.last_index < details.first_index)
2832 details.last_index = ULONG_MAX;
2833
2834 i_mmap_lock_write(mapping);
2835 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
2836 unmap_mapping_range_tree(&mapping->i_mmap, &details);
2837 i_mmap_unlock_write(mapping);
2838}
2839
2840/**
2841 * unmap_mapping_range - unmap the portion of all mmaps in the specified
2842 * address_space corresponding to the specified byte range in the underlying
2843 * file.
2844 *
2845 * @mapping: the address space containing mmaps to be unmapped.
2846 * @holebegin: byte in first page to unmap, relative to the start of
2847 * the underlying file. This will be rounded down to a PAGE_SIZE
2848 * boundary. Note that this is different from truncate_pagecache(), which
2849 * must keep the partial page. In contrast, we must get rid of
2850 * partial pages.
2851 * @holelen: size of prospective hole in bytes. This will be rounded
2852 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
2853 * end of the file.
2854 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
2855 * but 0 when invalidating pagecache, don't throw away private data.
2856 */
2857void unmap_mapping_range(struct address_space *mapping,
2858 loff_t const holebegin, loff_t const holelen, int even_cows)
2859{
2860 pgoff_t hba = holebegin >> PAGE_SHIFT;
2861 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2862
2863 /* Check for overflow. */
2864 if (sizeof(holelen) > sizeof(hlen)) {
2865 long long holeend =
2866 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
2867 if (holeend & ~(long long)ULONG_MAX)
2868 hlen = ULONG_MAX - hba + 1;
2869 }
2870
2871 unmap_mapping_pages(mapping, hba, hlen, even_cows);
2872}
2873EXPORT_SYMBOL(unmap_mapping_range);
2874
2875/*
2876 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2877 * but allow concurrent faults), and pte mapped but not yet locked.
2878 * We return with pte unmapped and unlocked.
2879 *
2880 * We return with the mmap_sem locked or unlocked in the same cases
2881 * as does filemap_fault().
2882 */
2883int do_swap_page(struct vm_fault *vmf)
2884{
2885 struct vm_area_struct *vma = vmf->vma;
2886 struct page *page = NULL, *swapcache;
2887 struct mem_cgroup *memcg;
2888 swp_entry_t entry;
2889 pte_t pte;
2890 int locked;
2891 int exclusive = 0;
2892 int ret = 0;
2893
2894 if (!pte_unmap_same(vma->vm_mm, vmf->pmd, vmf->pte, vmf->orig_pte))
2895 goto out;
2896
2897 entry = pte_to_swp_entry(vmf->orig_pte);
2898 if (unlikely(non_swap_entry(entry))) {
2899 if (is_migration_entry(entry)) {
2900 migration_entry_wait(vma->vm_mm, vmf->pmd,
2901 vmf->address);
2902 } else if (is_device_private_entry(entry)) {
2903 /*
2904 * For un-addressable device memory we call the pgmap
2905 * fault handler callback. The callback must migrate
2906 * the page back to some CPU accessible page.
2907 */
2908 ret = device_private_entry_fault(vma, vmf->address, entry,
2909 vmf->flags, vmf->pmd);
2910 } else if (is_hwpoison_entry(entry)) {
2911 ret = VM_FAULT_HWPOISON;
2912 } else {
2913 print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
2914 ret = VM_FAULT_SIGBUS;
2915 }
2916 goto out;
2917 }
2918
2919
2920 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
2921 page = lookup_swap_cache(entry, vma, vmf->address);
2922 swapcache = page;
2923
2924 if (!page) {
2925 struct swap_info_struct *si = swp_swap_info(entry);
2926
2927 if (si->flags & SWP_SYNCHRONOUS_IO &&
2928 __swap_count(si, entry) == 1) {
2929 /* skip swapcache */
2930 page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma,
2931 vmf->address);
2932 if (page) {
2933 __SetPageLocked(page);
2934 __SetPageSwapBacked(page);
2935 set_page_private(page, entry.val);
2936 lru_cache_add_anon(page);
2937 swap_readpage(page, true);
2938 }
2939 } else {
2940 page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
2941 vmf);
2942 swapcache = page;
2943 }
2944
2945 if (!page) {
2946 /*
2947 * Back out if somebody else faulted in this pte
2948 * while we released the pte lock.
2949 */
2950 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
2951 vmf->address, &vmf->ptl);
2952 if (likely(pte_same(*vmf->pte, vmf->orig_pte)))
2953 ret = VM_FAULT_OOM;
2954 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2955 goto unlock;
2956 }
2957
2958 /* Had to read the page from swap area: Major fault */
2959 ret = VM_FAULT_MAJOR;
2960 count_vm_event(PGMAJFAULT);
2961 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
2962 } else if (PageHWPoison(page)) {
2963 /*
2964 * hwpoisoned dirty swapcache pages are kept for killing
2965 * owner processes (which may be unknown at hwpoison time)
2966 */
2967 ret = VM_FAULT_HWPOISON;
2968 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2969 goto out_release;
2970 }
2971
2972 locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
2973
2974 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
2975 if (!locked) {
2976 ret |= VM_FAULT_RETRY;
2977 goto out_release;
2978 }
2979
2980 /*
2981 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
2982 * release the swapcache from under us. The page pin, and pte_same
2983 * test below, are not enough to exclude that. Even if it is still
2984 * swapcache, we need to check that the page's swap has not changed.
2985 */
2986 if (unlikely((!PageSwapCache(page) ||
2987 page_private(page) != entry.val)) && swapcache)
2988 goto out_page;
2989
2990 page = ksm_might_need_to_copy(page, vma, vmf->address);
2991 if (unlikely(!page)) {
2992 ret = VM_FAULT_OOM;
2993 page = swapcache;
2994 goto out_page;
2995 }
2996
2997 if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL,
2998 &memcg, false)) {
2999 ret = VM_FAULT_OOM;
3000 goto out_page;
3001 }
3002
3003 /*
3004 * Back out if somebody else already faulted in this pte.
3005 */
3006 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3007 &vmf->ptl);
3008 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte)))
3009 goto out_nomap;
3010
3011 if (unlikely(!PageUptodate(page))) {
3012 ret = VM_FAULT_SIGBUS;
3013 goto out_nomap;
3014 }
3015
3016 /*
3017 * The page isn't present yet, go ahead with the fault.
3018 *
3019 * Be careful about the sequence of operations here.
3020 * To get its accounting right, reuse_swap_page() must be called
3021 * while the page is counted on swap but not yet in mapcount i.e.
3022 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
3023 * must be called after the swap_free(), or it will never succeed.
3024 */
3025
3026 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3027 dec_mm_counter_fast(vma->vm_mm, MM_SWAPENTS);
3028 pte = mk_pte(page, vma->vm_page_prot);
3029 if ((vmf->flags & FAULT_FLAG_WRITE) && reuse_swap_page(page, NULL)) {
3030 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
3031 vmf->flags &= ~FAULT_FLAG_WRITE;
3032 ret |= VM_FAULT_WRITE;
3033 exclusive = RMAP_EXCLUSIVE;
3034 }
3035 flush_icache_page(vma, page);
3036 if (pte_swp_soft_dirty(vmf->orig_pte))
3037 pte = pte_mksoft_dirty(pte);
3038 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
3039 arch_do_swap_page(vma->vm_mm, vma, vmf->address, pte, vmf->orig_pte);
3040 vmf->orig_pte = pte;
3041
3042 /* ksm created a completely new copy */
3043 if (unlikely(page != swapcache && swapcache)) {
3044 page_add_new_anon_rmap(page, vma, vmf->address, false);
3045 mem_cgroup_commit_charge(page, memcg, false, false);
3046 lru_cache_add_active_or_unevictable(page, vma);
3047 } else {
3048 do_page_add_anon_rmap(page, vma, vmf->address, exclusive);
3049 mem_cgroup_commit_charge(page, memcg, true, false);
3050 activate_page(page);
3051 }
3052
3053 swap_free(entry);
3054 if (mem_cgroup_swap_full(page) ||
3055 (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
3056 try_to_free_swap(page);
3057 unlock_page(page);
3058 if (page != swapcache && swapcache) {
3059 /*
3060 * Hold the lock to avoid the swap entry to be reused
3061 * until we take the PT lock for the pte_same() check
3062 * (to avoid false positives from pte_same). For
3063 * further safety release the lock after the swap_free
3064 * so that the swap count won't change under a
3065 * parallel locked swapcache.
3066 */
3067 unlock_page(swapcache);
3068 put_page(swapcache);
3069 }
3070
3071 if (vmf->flags & FAULT_FLAG_WRITE) {
3072 ret |= do_wp_page(vmf);
3073 if (ret & VM_FAULT_ERROR)
3074 ret &= VM_FAULT_ERROR;
3075 goto out;
3076 }
3077
3078 /* No need to invalidate - it was non-present before */
3079 update_mmu_cache(vma, vmf->address, vmf->pte);
3080unlock:
3081 pte_unmap_unlock(vmf->pte, vmf->ptl);
3082out:
3083 return ret;
3084out_nomap:
3085 mem_cgroup_cancel_charge(page, memcg, false);
3086 pte_unmap_unlock(vmf->pte, vmf->ptl);
3087out_page:
3088 unlock_page(page);
3089out_release:
3090 put_page(page);
3091 if (page != swapcache && swapcache) {
3092 unlock_page(swapcache);
3093 put_page(swapcache);
3094 }
3095 return ret;
3096}
3097
3098/*
3099 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3100 * but allow concurrent faults), and pte mapped but not yet locked.
3101 * We return with mmap_sem still held, but pte unmapped and unlocked.
3102 */
3103static int do_anonymous_page(struct vm_fault *vmf)
3104{
3105 struct vm_area_struct *vma = vmf->vma;
3106 struct mem_cgroup *memcg;
3107 struct page *page;
3108 int ret = 0;
3109 pte_t entry;
3110
3111 /* File mapping without ->vm_ops ? */
3112 if (vma->vm_flags & VM_SHARED)
3113 return VM_FAULT_SIGBUS;
3114
3115 /*
3116 * Use pte_alloc() instead of pte_alloc_map(). We can't run
3117 * pte_offset_map() on pmds where a huge pmd might be created
3118 * from a different thread.
3119 *
3120 * pte_alloc_map() is safe to use under down_write(mmap_sem) or when
3121 * parallel threads are excluded by other means.
3122 *
3123 * Here we only have down_read(mmap_sem).
3124 */
3125 if (pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))
3126 return VM_FAULT_OOM;
3127
3128 /* See the comment in pte_alloc_one_map() */
3129 if (unlikely(pmd_trans_unstable(vmf->pmd)))
3130 return 0;
3131
3132 /* Use the zero-page for reads */
3133 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
3134 !mm_forbids_zeropage(vma->vm_mm)) {
3135 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
3136 vma->vm_page_prot));
3137 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
3138 vmf->address, &vmf->ptl);
3139 if (!pte_none(*vmf->pte))
3140 goto unlock;
3141 ret = check_stable_address_space(vma->vm_mm);
3142 if (ret)
3143 goto unlock;
3144 /* Deliver the page fault to userland, check inside PT lock */
3145 if (userfaultfd_missing(vma)) {
3146 pte_unmap_unlock(vmf->pte, vmf->ptl);
3147 return handle_userfault(vmf, VM_UFFD_MISSING);
3148 }
3149 goto setpte;
3150 }
3151
3152 /* Allocate our own private page. */
3153 if (unlikely(anon_vma_prepare(vma)))
3154 goto oom;
3155 page = alloc_zeroed_user_highpage_movable(vma, vmf->address);
3156 if (!page)
3157 goto oom;
3158
3159 if (mem_cgroup_try_charge(page, vma->vm_mm, GFP_KERNEL, &memcg, false))
3160 goto oom_free_page;
3161
3162 /*
3163 * The memory barrier inside __SetPageUptodate makes sure that
3164 * preceeding stores to the page contents become visible before
3165 * the set_pte_at() write.
3166 */
3167 __SetPageUptodate(page);
3168
3169 entry = mk_pte(page, vma->vm_page_prot);
3170 if (vma->vm_flags & VM_WRITE)
3171 entry = pte_mkwrite(pte_mkdirty(entry));
3172
3173 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3174 &vmf->ptl);
3175 if (!pte_none(*vmf->pte))
3176 goto release;
3177
3178 ret = check_stable_address_space(vma->vm_mm);
3179 if (ret)
3180 goto release;
3181
3182 /* Deliver the page fault to userland, check inside PT lock */
3183 if (userfaultfd_missing(vma)) {
3184 pte_unmap_unlock(vmf->pte, vmf->ptl);
3185 mem_cgroup_cancel_charge(page, memcg, false);
3186 put_page(page);
3187 return handle_userfault(vmf, VM_UFFD_MISSING);
3188 }
3189
3190 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3191 page_add_new_anon_rmap(page, vma, vmf->address, false);
3192 mem_cgroup_commit_charge(page, memcg, false, false);
3193 lru_cache_add_active_or_unevictable(page, vma);
3194setpte:
3195 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3196
3197 /* No need to invalidate - it was non-present before */
3198 update_mmu_cache(vma, vmf->address, vmf->pte);
3199unlock:
3200 pte_unmap_unlock(vmf->pte, vmf->ptl);
3201 return ret;
3202release:
3203 mem_cgroup_cancel_charge(page, memcg, false);
3204 put_page(page);
3205 goto unlock;
3206oom_free_page:
3207 put_page(page);
3208oom:
3209 return VM_FAULT_OOM;
3210}
3211
3212/*
3213 * The mmap_sem must have been held on entry, and may have been
3214 * released depending on flags and vma->vm_ops->fault() return value.
3215 * See filemap_fault() and __lock_page_retry().
3216 */
3217static int __do_fault(struct vm_fault *vmf)
3218{
3219 struct vm_area_struct *vma = vmf->vma;
3220 int ret;
3221
3222 ret = vma->vm_ops->fault(vmf);
3223 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
3224 VM_FAULT_DONE_COW)))
3225 return ret;
3226
3227 if (unlikely(PageHWPoison(vmf->page))) {
3228 if (ret & VM_FAULT_LOCKED)
3229 unlock_page(vmf->page);
3230 put_page(vmf->page);
3231 vmf->page = NULL;
3232 return VM_FAULT_HWPOISON;
3233 }
3234
3235 if (unlikely(!(ret & VM_FAULT_LOCKED)))
3236 lock_page(vmf->page);
3237 else
3238 VM_BUG_ON_PAGE(!PageLocked(vmf->page), vmf->page);
3239
3240 return ret;
3241}
3242
3243/*
3244 * The ordering of these checks is important for pmds with _PAGE_DEVMAP set.
3245 * If we check pmd_trans_unstable() first we will trip the bad_pmd() check
3246 * inside of pmd_none_or_trans_huge_or_clear_bad(). This will end up correctly
3247 * returning 1 but not before it spams dmesg with the pmd_clear_bad() output.
3248 */
3249static int pmd_devmap_trans_unstable(pmd_t *pmd)
3250{
3251 return pmd_devmap(*pmd) || pmd_trans_unstable(pmd);
3252}
3253
3254static int pte_alloc_one_map(struct vm_fault *vmf)
3255{
3256 struct vm_area_struct *vma = vmf->vma;
3257
3258 if (!pmd_none(*vmf->pmd))
3259 goto map_pte;
3260 if (vmf->prealloc_pte) {
3261 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3262 if (unlikely(!pmd_none(*vmf->pmd))) {
3263 spin_unlock(vmf->ptl);
3264 goto map_pte;
3265 }
3266
3267 mm_inc_nr_ptes(vma->vm_mm);
3268 pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3269 spin_unlock(vmf->ptl);
3270 vmf->prealloc_pte = NULL;
3271 } else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd, vmf->address))) {
3272 return VM_FAULT_OOM;
3273 }
3274map_pte:
3275 /*
3276 * If a huge pmd materialized under us just retry later. Use
3277 * pmd_trans_unstable() via pmd_devmap_trans_unstable() instead of
3278 * pmd_trans_huge() to ensure the pmd didn't become pmd_trans_huge
3279 * under us and then back to pmd_none, as a result of MADV_DONTNEED
3280 * running immediately after a huge pmd fault in a different thread of
3281 * this mm, in turn leading to a misleading pmd_trans_huge() retval.
3282 * All we have to ensure is that it is a regular pmd that we can walk
3283 * with pte_offset_map() and we can do that through an atomic read in
3284 * C, which is what pmd_trans_unstable() provides.
3285 */
3286 if (pmd_devmap_trans_unstable(vmf->pmd))
3287 return VM_FAULT_NOPAGE;
3288
3289 /*
3290 * At this point we know that our vmf->pmd points to a page of ptes
3291 * and it cannot become pmd_none(), pmd_devmap() or pmd_trans_huge()
3292 * for the duration of the fault. If a racing MADV_DONTNEED runs and
3293 * we zap the ptes pointed to by our vmf->pmd, the vmf->ptl will still
3294 * be valid and we will re-check to make sure the vmf->pte isn't
3295 * pte_none() under vmf->ptl protection when we return to
3296 * alloc_set_pte().
3297 */
3298 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3299 &vmf->ptl);
3300 return 0;
3301}
3302
3303#ifdef CONFIG_TRANSPARENT_HUGE_PAGECACHE
3304
3305#define HPAGE_CACHE_INDEX_MASK (HPAGE_PMD_NR - 1)
3306static inline bool transhuge_vma_suitable(struct vm_area_struct *vma,
3307 unsigned long haddr)
3308{
3309 if (((vma->vm_start >> PAGE_SHIFT) & HPAGE_CACHE_INDEX_MASK) !=
3310 (vma->vm_pgoff & HPAGE_CACHE_INDEX_MASK))
3311 return false;
3312 if (haddr < vma->vm_start || haddr + HPAGE_PMD_SIZE > vma->vm_end)
3313 return false;
3314 return true;
3315}
3316
3317static void deposit_prealloc_pte(struct vm_fault *vmf)
3318{
3319 struct vm_area_struct *vma = vmf->vma;
3320
3321 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
3322 /*
3323 * We are going to consume the prealloc table,
3324 * count that as nr_ptes.
3325 */
3326 mm_inc_nr_ptes(vma->vm_mm);
3327 vmf->prealloc_pte = NULL;
3328}
3329
3330static int do_set_pmd(struct vm_fault *vmf, struct page *page)
3331{
3332 struct vm_area_struct *vma = vmf->vma;
3333 bool write = vmf->flags & FAULT_FLAG_WRITE;
3334 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
3335 pmd_t entry;
3336 int i, ret;
3337
3338 if (!transhuge_vma_suitable(vma, haddr))
3339 return VM_FAULT_FALLBACK;
3340
3341 ret = VM_FAULT_FALLBACK;
3342 page = compound_head(page);
3343
3344 /*
3345 * Archs like ppc64 need additonal space to store information
3346 * related to pte entry. Use the preallocated table for that.
3347 */
3348 if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
3349 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm, vmf->address);
3350 if (!vmf->prealloc_pte)
3351 return VM_FAULT_OOM;
3352 smp_wmb(); /* See comment in __pte_alloc() */
3353 }
3354
3355 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
3356 if (unlikely(!pmd_none(*vmf->pmd)))
3357 goto out;
3358
3359 for (i = 0; i < HPAGE_PMD_NR; i++)
3360 flush_icache_page(vma, page + i);
3361
3362 entry = mk_huge_pmd(page, vma->vm_page_prot);
3363 if (write)
3364 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
3365
3366 add_mm_counter(vma->vm_mm, MM_FILEPAGES, HPAGE_PMD_NR);
3367 page_add_file_rmap(page, true);
3368 /*
3369 * deposit and withdraw with pmd lock held
3370 */
3371 if (arch_needs_pgtable_deposit())
3372 deposit_prealloc_pte(vmf);
3373
3374 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
3375
3376 update_mmu_cache_pmd(vma, haddr, vmf->pmd);
3377
3378 /* fault is handled */
3379 ret = 0;
3380 count_vm_event(THP_FILE_MAPPED);
3381out:
3382 spin_unlock(vmf->ptl);
3383 return ret;
3384}
3385#else
3386static int do_set_pmd(struct vm_fault *vmf, struct page *page)
3387{
3388 BUILD_BUG();
3389 return 0;
3390}
3391#endif
3392
3393/**
3394 * alloc_set_pte - setup new PTE entry for given page and add reverse page
3395 * mapping. If needed, the fucntion allocates page table or use pre-allocated.
3396 *
3397 * @vmf: fault environment
3398 * @memcg: memcg to charge page (only for private mappings)
3399 * @page: page to map
3400 *
3401 * Caller must take care of unlocking vmf->ptl, if vmf->pte is non-NULL on
3402 * return.
3403 *
3404 * Target users are page handler itself and implementations of
3405 * vm_ops->map_pages.
3406 */
3407int alloc_set_pte(struct vm_fault *vmf, struct mem_cgroup *memcg,
3408 struct page *page)
3409{
3410 struct vm_area_struct *vma = vmf->vma;
3411 bool write = vmf->flags & FAULT_FLAG_WRITE;
3412 pte_t entry;
3413 int ret;
3414
3415 if (pmd_none(*vmf->pmd) && PageTransCompound(page) &&
3416 IS_ENABLED(CONFIG_TRANSPARENT_HUGE_PAGECACHE)) {
3417 /* THP on COW? */
3418 VM_BUG_ON_PAGE(memcg, page);
3419
3420 ret = do_set_pmd(vmf, page);
3421 if (ret != VM_FAULT_FALLBACK)
3422 return ret;
3423 }
3424
3425 if (!vmf->pte) {
3426 ret = pte_alloc_one_map(vmf);
3427 if (ret)
3428 return ret;
3429 }
3430
3431 /* Re-check under ptl */
3432 if (unlikely(!pte_none(*vmf->pte)))
3433 return VM_FAULT_NOPAGE;
3434
3435 flush_icache_page(vma, page);
3436 entry = mk_pte(page, vma->vm_page_prot);
3437 if (write)
3438 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3439 /* copy-on-write page */
3440 if (write && !(vma->vm_flags & VM_SHARED)) {
3441 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3442 page_add_new_anon_rmap(page, vma, vmf->address, false);
3443 mem_cgroup_commit_charge(page, memcg, false, false);
3444 lru_cache_add_active_or_unevictable(page, vma);
3445 } else {
3446 inc_mm_counter_fast(vma->vm_mm, mm_counter_file(page));
3447 page_add_file_rmap(page, false);
3448 }
3449 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, entry);
3450
3451 /* no need to invalidate: a not-present page won't be cached */
3452 update_mmu_cache(vma, vmf->address, vmf->pte);
3453
3454 return 0;
3455}
3456
3457
3458/**
3459 * finish_fault - finish page fault once we have prepared the page to fault
3460 *
3461 * @vmf: structure describing the fault
3462 *
3463 * This function handles all that is needed to finish a page fault once the
3464 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
3465 * given page, adds reverse page mapping, handles memcg charges and LRU
3466 * addition. The function returns 0 on success, VM_FAULT_ code in case of
3467 * error.
3468 *
3469 * The function expects the page to be locked and on success it consumes a
3470 * reference of a page being mapped (for the PTE which maps it).
3471 */
3472int finish_fault(struct vm_fault *vmf)
3473{
3474 struct page *page;
3475 int ret = 0;
3476
3477 /* Did we COW the page? */
3478 if ((vmf->flags & FAULT_FLAG_WRITE) &&
3479 !(vmf->vma->vm_flags & VM_SHARED))
3480 page = vmf->cow_page;
3481 else
3482 page = vmf->page;
3483
3484 /*
3485 * check even for read faults because we might have lost our CoWed
3486 * page
3487 */
3488 if (!(vmf->vma->vm_flags & VM_SHARED))
3489 ret = check_stable_address_space(vmf->vma->vm_mm);
3490 if (!ret)
3491 ret = alloc_set_pte(vmf, vmf->memcg, page);
3492 if (vmf->pte)
3493 pte_unmap_unlock(vmf->pte, vmf->ptl);
3494 return ret;
3495}
3496
3497static unsigned long fault_around_bytes __read_mostly =
3498 rounddown_pow_of_two(65536);
3499
3500#ifdef CONFIG_DEBUG_FS
3501static int fault_around_bytes_get(void *data, u64 *val)
3502{
3503 *val = fault_around_bytes;
3504 return 0;
3505}
3506
3507/*
3508 * fault_around_bytes must be rounded down to the nearest page order as it's
3509 * what do_fault_around() expects to see.
3510 */
3511static int fault_around_bytes_set(void *data, u64 val)
3512{
3513 if (val / PAGE_SIZE > PTRS_PER_PTE)
3514 return -EINVAL;
3515 if (val > PAGE_SIZE)
3516 fault_around_bytes = rounddown_pow_of_two(val);
3517 else
3518 fault_around_bytes = PAGE_SIZE; /* rounddown_pow_of_two(0) is undefined */
3519 return 0;
3520}
3521DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
3522 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
3523
3524static int __init fault_around_debugfs(void)
3525{
3526 void *ret;
3527
3528 ret = debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
3529 &fault_around_bytes_fops);
3530 if (!ret)
3531 pr_warn("Failed to create fault_around_bytes in debugfs");
3532 return 0;
3533}
3534late_initcall(fault_around_debugfs);
3535#endif
3536
3537/*
3538 * do_fault_around() tries to map few pages around the fault address. The hope
3539 * is that the pages will be needed soon and this will lower the number of
3540 * faults to handle.
3541 *
3542 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
3543 * not ready to be mapped: not up-to-date, locked, etc.
3544 *
3545 * This function is called with the page table lock taken. In the split ptlock
3546 * case the page table lock only protects only those entries which belong to
3547 * the page table corresponding to the fault address.
3548 *
3549 * This function doesn't cross the VMA boundaries, in order to call map_pages()
3550 * only once.
3551 *
3552 * fault_around_bytes defines how many bytes we'll try to map.
3553 * do_fault_around() expects it to be set to a power of two less than or equal
3554 * to PTRS_PER_PTE.
3555 *
3556 * The virtual address of the area that we map is naturally aligned to
3557 * fault_around_bytes rounded down to the machine page size
3558 * (and therefore to page order). This way it's easier to guarantee
3559 * that we don't cross page table boundaries.
3560 */
3561static int do_fault_around(struct vm_fault *vmf)
3562{
3563 unsigned long address = vmf->address, nr_pages, mask;
3564 pgoff_t start_pgoff = vmf->pgoff;
3565 pgoff_t end_pgoff;
3566 int off, ret = 0;
3567
3568 nr_pages = READ_ONCE(fault_around_bytes) >> PAGE_SHIFT;
3569 mask = ~(nr_pages * PAGE_SIZE - 1) & PAGE_MASK;
3570
3571 vmf->address = max(address & mask, vmf->vma->vm_start);
3572 off = ((address - vmf->address) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
3573 start_pgoff -= off;
3574
3575 /*
3576 * end_pgoff is either the end of the page table, the end of
3577 * the vma or nr_pages from start_pgoff, depending what is nearest.
3578 */
3579 end_pgoff = start_pgoff -
3580 ((vmf->address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
3581 PTRS_PER_PTE - 1;
3582 end_pgoff = min3(end_pgoff, vma_pages(vmf->vma) + vmf->vma->vm_pgoff - 1,
3583 start_pgoff + nr_pages - 1);
3584
3585 if (pmd_none(*vmf->pmd)) {
3586 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm,
3587 vmf->address);
3588 if (!vmf->prealloc_pte)
3589 goto out;
3590 smp_wmb(); /* See comment in __pte_alloc() */
3591 }
3592
3593 vmf->vma->vm_ops->map_pages(vmf, start_pgoff, end_pgoff);
3594
3595 /* Huge page is mapped? Page fault is solved */
3596 if (pmd_trans_huge(*vmf->pmd)) {
3597 ret = VM_FAULT_NOPAGE;
3598 goto out;
3599 }
3600
3601 /* ->map_pages() haven't done anything useful. Cold page cache? */
3602 if (!vmf->pte)
3603 goto out;
3604
3605 /* check if the page fault is solved */
3606 vmf->pte -= (vmf->address >> PAGE_SHIFT) - (address >> PAGE_SHIFT);
3607 if (!pte_none(*vmf->pte))
3608 ret = VM_FAULT_NOPAGE;
3609 pte_unmap_unlock(vmf->pte, vmf->ptl);
3610out:
3611 vmf->address = address;
3612 vmf->pte = NULL;
3613 return ret;
3614}
3615
3616static int do_read_fault(struct vm_fault *vmf)
3617{
3618 struct vm_area_struct *vma = vmf->vma;
3619 int ret = 0;
3620
3621 /*
3622 * Let's call ->map_pages() first and use ->fault() as fallback
3623 * if page by the offset is not ready to be mapped (cold cache or
3624 * something).
3625 */
3626 if (vma->vm_ops->map_pages && fault_around_bytes >> PAGE_SHIFT > 1) {
3627 ret = do_fault_around(vmf);
3628 if (ret)
3629 return ret;
3630 }
3631
3632 ret = __do_fault(vmf);
3633 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3634 return ret;
3635
3636 ret |= finish_fault(vmf);
3637 unlock_page(vmf->page);
3638 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3639 put_page(vmf->page);
3640 return ret;
3641}
3642
3643static int do_cow_fault(struct vm_fault *vmf)
3644{
3645 struct vm_area_struct *vma = vmf->vma;
3646 int ret;
3647
3648 if (unlikely(anon_vma_prepare(vma)))
3649 return VM_FAULT_OOM;
3650
3651 vmf->cow_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, vmf->address);
3652 if (!vmf->cow_page)
3653 return VM_FAULT_OOM;
3654
3655 if (mem_cgroup_try_charge(vmf->cow_page, vma->vm_mm, GFP_KERNEL,
3656 &vmf->memcg, false)) {
3657 put_page(vmf->cow_page);
3658 return VM_FAULT_OOM;
3659 }
3660
3661 ret = __do_fault(vmf);
3662 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3663 goto uncharge_out;
3664 if (ret & VM_FAULT_DONE_COW)
3665 return ret;
3666
3667 copy_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma);
3668 __SetPageUptodate(vmf->cow_page);
3669
3670 ret |= finish_fault(vmf);
3671 unlock_page(vmf->page);
3672 put_page(vmf->page);
3673 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3674 goto uncharge_out;
3675 return ret;
3676uncharge_out:
3677 mem_cgroup_cancel_charge(vmf->cow_page, vmf->memcg, false);
3678 put_page(vmf->cow_page);
3679 return ret;
3680}
3681
3682static int do_shared_fault(struct vm_fault *vmf)
3683{
3684 struct vm_area_struct *vma = vmf->vma;
3685 int ret, tmp;
3686
3687 ret = __do_fault(vmf);
3688 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3689 return ret;
3690
3691 /*
3692 * Check if the backing address space wants to know that the page is
3693 * about to become writable
3694 */
3695 if (vma->vm_ops->page_mkwrite) {
3696 unlock_page(vmf->page);
3697 tmp = do_page_mkwrite(vmf);
3698 if (unlikely(!tmp ||
3699 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3700 put_page(vmf->page);
3701 return tmp;
3702 }
3703 }
3704
3705 ret |= finish_fault(vmf);
3706 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
3707 VM_FAULT_RETRY))) {
3708 unlock_page(vmf->page);
3709 put_page(vmf->page);
3710 return ret;
3711 }
3712
3713 fault_dirty_shared_page(vma, vmf->page);
3714 return ret;
3715}
3716
3717/*
3718 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3719 * but allow concurrent faults).
3720 * The mmap_sem may have been released depending on flags and our
3721 * return value. See filemap_fault() and __lock_page_or_retry().
3722 */
3723static int do_fault(struct vm_fault *vmf)
3724{
3725 struct vm_area_struct *vma = vmf->vma;
3726 int ret;
3727
3728 /* The VMA was not fully populated on mmap() or missing VM_DONTEXPAND */
3729 if (!vma->vm_ops->fault)
3730 ret = VM_FAULT_SIGBUS;
3731 else if (!(vmf->flags & FAULT_FLAG_WRITE))
3732 ret = do_read_fault(vmf);
3733 else if (!(vma->vm_flags & VM_SHARED))
3734 ret = do_cow_fault(vmf);
3735 else
3736 ret = do_shared_fault(vmf);
3737
3738 /* preallocated pagetable is unused: free it */
3739 if (vmf->prealloc_pte) {
3740 pte_free(vma->vm_mm, vmf->prealloc_pte);
3741 vmf->prealloc_pte = NULL;
3742 }
3743 return ret;
3744}
3745
3746static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3747 unsigned long addr, int page_nid,
3748 int *flags)
3749{
3750 get_page(page);
3751
3752 count_vm_numa_event(NUMA_HINT_FAULTS);
3753 if (page_nid == numa_node_id()) {
3754 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3755 *flags |= TNF_FAULT_LOCAL;
3756 }
3757
3758 return mpol_misplaced(page, vma, addr);
3759}
3760
3761static int do_numa_page(struct vm_fault *vmf)
3762{
3763 struct vm_area_struct *vma = vmf->vma;
3764 struct page *page = NULL;
3765 int page_nid = -1;
3766 int last_cpupid;
3767 int target_nid;
3768 bool migrated = false;
3769 pte_t pte;
3770 bool was_writable = pte_savedwrite(vmf->orig_pte);
3771 int flags = 0;
3772
3773 /*
3774 * The "pte" at this point cannot be used safely without
3775 * validation through pte_unmap_same(). It's of NUMA type but
3776 * the pfn may be screwed if the read is non atomic.
3777 */
3778 vmf->ptl = pte_lockptr(vma->vm_mm, vmf->pmd);
3779 spin_lock(vmf->ptl);
3780 if (unlikely(!pte_same(*vmf->pte, vmf->orig_pte))) {
3781 pte_unmap_unlock(vmf->pte, vmf->ptl);
3782 goto out;
3783 }
3784
3785 /*
3786 * Make it present again, Depending on how arch implementes non
3787 * accessible ptes, some can allow access by kernel mode.
3788 */
3789 pte = ptep_modify_prot_start(vma->vm_mm, vmf->address, vmf->pte);
3790 pte = pte_modify(pte, vma->vm_page_prot);
3791 pte = pte_mkyoung(pte);
3792 if (was_writable)
3793 pte = pte_mkwrite(pte);
3794 ptep_modify_prot_commit(vma->vm_mm, vmf->address, vmf->pte, pte);
3795 update_mmu_cache(vma, vmf->address, vmf->pte);
3796
3797 page = vm_normal_page(vma, vmf->address, pte);
3798 if (!page) {
3799 pte_unmap_unlock(vmf->pte, vmf->ptl);
3800 return 0;
3801 }
3802
3803 /* TODO: handle PTE-mapped THP */
3804 if (PageCompound(page)) {
3805 pte_unmap_unlock(vmf->pte, vmf->ptl);
3806 return 0;
3807 }
3808
3809 /*
3810 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
3811 * much anyway since they can be in shared cache state. This misses
3812 * the case where a mapping is writable but the process never writes
3813 * to it but pte_write gets cleared during protection updates and
3814 * pte_dirty has unpredictable behaviour between PTE scan updates,
3815 * background writeback, dirty balancing and application behaviour.
3816 */
3817 if (!pte_write(pte))
3818 flags |= TNF_NO_GROUP;
3819
3820 /*
3821 * Flag if the page is shared between multiple address spaces. This
3822 * is later used when determining whether to group tasks together
3823 */
3824 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
3825 flags |= TNF_SHARED;
3826
3827 last_cpupid = page_cpupid_last(page);
3828 page_nid = page_to_nid(page);
3829 target_nid = numa_migrate_prep(page, vma, vmf->address, page_nid,
3830 &flags);
3831 pte_unmap_unlock(vmf->pte, vmf->ptl);
3832 if (target_nid == -1) {
3833 put_page(page);
3834 goto out;
3835 }
3836
3837 /* Migrate to the requested node */
3838 migrated = migrate_misplaced_page(page, vma, target_nid);
3839 if (migrated) {
3840 page_nid = target_nid;
3841 flags |= TNF_MIGRATED;
3842 } else
3843 flags |= TNF_MIGRATE_FAIL;
3844
3845out:
3846 if (page_nid != -1)
3847 task_numa_fault(last_cpupid, page_nid, 1, flags);
3848 return 0;
3849}
3850
3851static inline int create_huge_pmd(struct vm_fault *vmf)
3852{
3853 if (vma_is_anonymous(vmf->vma))
3854 return do_huge_pmd_anonymous_page(vmf);
3855 if (vmf->vma->vm_ops->huge_fault)
3856 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3857 return VM_FAULT_FALLBACK;
3858}
3859
3860/* `inline' is required to avoid gcc 4.1.2 build error */
3861static inline int wp_huge_pmd(struct vm_fault *vmf, pmd_t orig_pmd)
3862{
3863 if (vma_is_anonymous(vmf->vma))
3864 return do_huge_pmd_wp_page(vmf, orig_pmd);
3865 if (vmf->vma->vm_ops->huge_fault)
3866 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PMD);
3867
3868 /* COW handled on pte level: split pmd */
3869 VM_BUG_ON_VMA(vmf->vma->vm_flags & VM_SHARED, vmf->vma);
3870 __split_huge_pmd(vmf->vma, vmf->pmd, vmf->address, false, NULL);
3871
3872 return VM_FAULT_FALLBACK;
3873}
3874
3875static inline bool vma_is_accessible(struct vm_area_struct *vma)
3876{
3877 return vma->vm_flags & (VM_READ | VM_EXEC | VM_WRITE);
3878}
3879
3880static int create_huge_pud(struct vm_fault *vmf)
3881{
3882#ifdef CONFIG_TRANSPARENT_HUGEPAGE
3883 /* No support for anonymous transparent PUD pages yet */
3884 if (vma_is_anonymous(vmf->vma))
3885 return VM_FAULT_FALLBACK;
3886 if (vmf->vma->vm_ops->huge_fault)
3887 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3888#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3889 return VM_FAULT_FALLBACK;
3890}
3891
3892static int wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
3893{
3894#ifdef CONFIG_TRANSPARENT_HUGEPAGE
3895 /* No support for anonymous transparent PUD pages yet */
3896 if (vma_is_anonymous(vmf->vma))
3897 return VM_FAULT_FALLBACK;
3898 if (vmf->vma->vm_ops->huge_fault)
3899 return vmf->vma->vm_ops->huge_fault(vmf, PE_SIZE_PUD);
3900#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
3901 return VM_FAULT_FALLBACK;
3902}
3903
3904/*
3905 * These routines also need to handle stuff like marking pages dirty
3906 * and/or accessed for architectures that don't do it in hardware (most
3907 * RISC architectures). The early dirtying is also good on the i386.
3908 *
3909 * There is also a hook called "update_mmu_cache()" that architectures
3910 * with external mmu caches can use to update those (ie the Sparc or
3911 * PowerPC hashed page tables that act as extended TLBs).
3912 *
3913 * We enter with non-exclusive mmap_sem (to exclude vma changes, but allow
3914 * concurrent faults).
3915 *
3916 * The mmap_sem may have been released depending on flags and our return value.
3917 * See filemap_fault() and __lock_page_or_retry().
3918 */
3919static int handle_pte_fault(struct vm_fault *vmf)
3920{
3921 pte_t entry;
3922
3923 if (unlikely(pmd_none(*vmf->pmd))) {
3924 /*
3925 * Leave __pte_alloc() until later: because vm_ops->fault may
3926 * want to allocate huge page, and if we expose page table
3927 * for an instant, it will be difficult to retract from
3928 * concurrent faults and from rmap lookups.
3929 */
3930 vmf->pte = NULL;
3931 } else {
3932 /* See comment in pte_alloc_one_map() */
3933 if (pmd_devmap_trans_unstable(vmf->pmd))
3934 return 0;
3935 /*
3936 * A regular pmd is established and it can't morph into a huge
3937 * pmd from under us anymore at this point because we hold the
3938 * mmap_sem read mode and khugepaged takes it in write mode.
3939 * So now it's safe to run pte_offset_map().
3940 */
3941 vmf->pte = pte_offset_map(vmf->pmd, vmf->address);
3942 vmf->orig_pte = *vmf->pte;
3943
3944 /*
3945 * some architectures can have larger ptes than wordsize,
3946 * e.g.ppc44x-defconfig has CONFIG_PTE_64BIT=y and
3947 * CONFIG_32BIT=y, so READ_ONCE cannot guarantee atomic
3948 * accesses. The code below just needs a consistent view
3949 * for the ifs and we later double check anyway with the
3950 * ptl lock held. So here a barrier will do.
3951 */
3952 barrier();
3953 if (pte_none(vmf->orig_pte)) {
3954 pte_unmap(vmf->pte);
3955 vmf->pte = NULL;
3956 }
3957 }
3958
3959 if (!vmf->pte) {
3960 if (vma_is_anonymous(vmf->vma))
3961 return do_anonymous_page(vmf);
3962 else
3963 return do_fault(vmf);
3964 }
3965
3966 if (!pte_present(vmf->orig_pte))
3967 return do_swap_page(vmf);
3968
3969 if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
3970 return do_numa_page(vmf);
3971
3972 vmf->ptl = pte_lockptr(vmf->vma->vm_mm, vmf->pmd);
3973 spin_lock(vmf->ptl);
3974 entry = vmf->orig_pte;
3975 if (unlikely(!pte_same(*vmf->pte, entry)))
3976 goto unlock;
3977 if (vmf->flags & FAULT_FLAG_WRITE) {
3978 if (!pte_write(entry))
3979 return do_wp_page(vmf);
3980 entry = pte_mkdirty(entry);
3981 }
3982 entry = pte_mkyoung(entry);
3983 if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
3984 vmf->flags & FAULT_FLAG_WRITE)) {
3985 update_mmu_cache(vmf->vma, vmf->address, vmf->pte);
3986 } else {
3987 /*
3988 * This is needed only for protection faults but the arch code
3989 * is not yet telling us if this is a protection fault or not.
3990 * This still avoids useless tlb flushes for .text page faults
3991 * with threads.
3992 */
3993 if (vmf->flags & FAULT_FLAG_WRITE)
3994 flush_tlb_fix_spurious_fault(vmf->vma, vmf->address);
3995 }
3996unlock:
3997 pte_unmap_unlock(vmf->pte, vmf->ptl);
3998 return 0;
3999}
4000
4001/*
4002 * By the time we get here, we already hold the mm semaphore
4003 *
4004 * The mmap_sem may have been released depending on flags and our
4005 * return value. See filemap_fault() and __lock_page_or_retry().
4006 */
4007static int __handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
4008 unsigned int flags)
4009{
4010 struct vm_fault vmf = {
4011 .vma = vma,
4012 .address = address & PAGE_MASK,
4013 .flags = flags,
4014 .pgoff = linear_page_index(vma, address),
4015 .gfp_mask = __get_fault_gfp_mask(vma),
4016 };
4017 unsigned int dirty = flags & FAULT_FLAG_WRITE;
4018 struct mm_struct *mm = vma->vm_mm;
4019 pgd_t *pgd;
4020 p4d_t *p4d;
4021 int ret;
4022
4023 pgd = pgd_offset(mm, address);
4024 p4d = p4d_alloc(mm, pgd, address);
4025 if (!p4d)
4026 return VM_FAULT_OOM;
4027
4028 vmf.pud = pud_alloc(mm, p4d, address);
4029 if (!vmf.pud)
4030 return VM_FAULT_OOM;
4031 if (pud_none(*vmf.pud) && transparent_hugepage_enabled(vma)) {
4032 ret = create_huge_pud(&vmf);
4033 if (!(ret & VM_FAULT_FALLBACK))
4034 return ret;
4035 } else {
4036 pud_t orig_pud = *vmf.pud;
4037
4038 barrier();
4039 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
4040
4041 /* NUMA case for anonymous PUDs would go here */
4042
4043 if (dirty && !pud_write(orig_pud)) {
4044 ret = wp_huge_pud(&vmf, orig_pud);
4045 if (!(ret & VM_FAULT_FALLBACK))
4046 return ret;
4047 } else {
4048 huge_pud_set_accessed(&vmf, orig_pud);
4049 return 0;
4050 }
4051 }
4052 }
4053
4054 vmf.pmd = pmd_alloc(mm, vmf.pud, address);
4055 if (!vmf.pmd)
4056 return VM_FAULT_OOM;
4057 if (pmd_none(*vmf.pmd) && transparent_hugepage_enabled(vma)) {
4058 ret = create_huge_pmd(&vmf);
4059 if (!(ret & VM_FAULT_FALLBACK))
4060 return ret;
4061 } else {
4062 pmd_t orig_pmd = *vmf.pmd;
4063
4064 barrier();
4065 if (unlikely(is_swap_pmd(orig_pmd))) {
4066 VM_BUG_ON(thp_migration_supported() &&
4067 !is_pmd_migration_entry(orig_pmd));
4068 if (is_pmd_migration_entry(orig_pmd))
4069 pmd_migration_entry_wait(mm, vmf.pmd);
4070 return 0;
4071 }
4072 if (pmd_trans_huge(orig_pmd) || pmd_devmap(orig_pmd)) {
4073 if (pmd_protnone(orig_pmd) && vma_is_accessible(vma))
4074 return do_huge_pmd_numa_page(&vmf, orig_pmd);
4075
4076 if (dirty && !pmd_write(orig_pmd)) {
4077 ret = wp_huge_pmd(&vmf, orig_pmd);
4078 if (!(ret & VM_FAULT_FALLBACK))
4079 return ret;
4080 } else {
4081 huge_pmd_set_accessed(&vmf, orig_pmd);
4082 return 0;
4083 }
4084 }
4085 }
4086
4087 return handle_pte_fault(&vmf);
4088}
4089
4090/*
4091 * By the time we get here, we already hold the mm semaphore
4092 *
4093 * The mmap_sem may have been released depending on flags and our
4094 * return value. See filemap_fault() and __lock_page_or_retry().
4095 */
4096int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
4097 unsigned int flags)
4098{
4099 int ret;
4100
4101 __set_current_state(TASK_RUNNING);
4102
4103 count_vm_event(PGFAULT);
4104 count_memcg_event_mm(vma->vm_mm, PGFAULT);
4105
4106 /* do counter updates before entering really critical section. */
4107 check_sync_rss_stat(current);
4108
4109 if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
4110 flags & FAULT_FLAG_INSTRUCTION,
4111 flags & FAULT_FLAG_REMOTE))
4112 return VM_FAULT_SIGSEGV;
4113
4114 /*
4115 * Enable the memcg OOM handling for faults triggered in user
4116 * space. Kernel faults are handled more gracefully.
4117 */
4118 if (flags & FAULT_FLAG_USER)
4119 mem_cgroup_oom_enable();
4120
4121 if (unlikely(is_vm_hugetlb_page(vma)))
4122 ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
4123 else
4124 ret = __handle_mm_fault(vma, address, flags);
4125
4126 if (flags & FAULT_FLAG_USER) {
4127 mem_cgroup_oom_disable();
4128 /*
4129 * The task may have entered a memcg OOM situation but
4130 * if the allocation error was handled gracefully (no
4131 * VM_FAULT_OOM), there is no need to kill anything.
4132 * Just clean up the OOM state peacefully.
4133 */
4134 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
4135 mem_cgroup_oom_synchronize(false);
4136 }
4137
4138 return ret;
4139}
4140EXPORT_SYMBOL_GPL(handle_mm_fault);
4141
4142#ifndef __PAGETABLE_P4D_FOLDED
4143/*
4144 * Allocate p4d page table.
4145 * We've already handled the fast-path in-line.
4146 */
4147int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
4148{
4149 p4d_t *new = p4d_alloc_one(mm, address);
4150 if (!new)
4151 return -ENOMEM;
4152
4153 smp_wmb(); /* See comment in __pte_alloc */
4154
4155 spin_lock(&mm->page_table_lock);
4156 if (pgd_present(*pgd)) /* Another has populated it */
4157 p4d_free(mm, new);
4158 else
4159 pgd_populate(mm, pgd, new);
4160 spin_unlock(&mm->page_table_lock);
4161 return 0;
4162}
4163#endif /* __PAGETABLE_P4D_FOLDED */
4164
4165#ifndef __PAGETABLE_PUD_FOLDED
4166/*
4167 * Allocate page upper directory.
4168 * We've already handled the fast-path in-line.
4169 */
4170int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
4171{
4172 pud_t *new = pud_alloc_one(mm, address);
4173 if (!new)
4174 return -ENOMEM;
4175
4176 smp_wmb(); /* See comment in __pte_alloc */
4177
4178 spin_lock(&mm->page_table_lock);
4179#ifndef __ARCH_HAS_5LEVEL_HACK
4180 if (!p4d_present(*p4d)) {
4181 mm_inc_nr_puds(mm);
4182 p4d_populate(mm, p4d, new);
4183 } else /* Another has populated it */
4184 pud_free(mm, new);
4185#else
4186 if (!pgd_present(*p4d)) {
4187 mm_inc_nr_puds(mm);
4188 pgd_populate(mm, p4d, new);
4189 } else /* Another has populated it */
4190 pud_free(mm, new);
4191#endif /* __ARCH_HAS_5LEVEL_HACK */
4192 spin_unlock(&mm->page_table_lock);
4193 return 0;
4194}
4195#endif /* __PAGETABLE_PUD_FOLDED */
4196
4197#ifndef __PAGETABLE_PMD_FOLDED
4198/*
4199 * Allocate page middle directory.
4200 * We've already handled the fast-path in-line.
4201 */
4202int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
4203{
4204 spinlock_t *ptl;
4205 pmd_t *new = pmd_alloc_one(mm, address);
4206 if (!new)
4207 return -ENOMEM;
4208
4209 smp_wmb(); /* See comment in __pte_alloc */
4210
4211 ptl = pud_lock(mm, pud);
4212#ifndef __ARCH_HAS_4LEVEL_HACK
4213 if (!pud_present(*pud)) {
4214 mm_inc_nr_pmds(mm);
4215 pud_populate(mm, pud, new);
4216 } else /* Another has populated it */
4217 pmd_free(mm, new);
4218#else
4219 if (!pgd_present(*pud)) {
4220 mm_inc_nr_pmds(mm);
4221 pgd_populate(mm, pud, new);
4222 } else /* Another has populated it */
4223 pmd_free(mm, new);
4224#endif /* __ARCH_HAS_4LEVEL_HACK */
4225 spin_unlock(ptl);
4226 return 0;
4227}
4228#endif /* __PAGETABLE_PMD_FOLDED */
4229
4230static int __follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4231 unsigned long *start, unsigned long *end,
4232 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4233{
4234 pgd_t *pgd;
4235 p4d_t *p4d;
4236 pud_t *pud;
4237 pmd_t *pmd;
4238 pte_t *ptep;
4239
4240 pgd = pgd_offset(mm, address);
4241 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
4242 goto out;
4243
4244 p4d = p4d_offset(pgd, address);
4245 if (p4d_none(*p4d) || unlikely(p4d_bad(*p4d)))
4246 goto out;
4247
4248 pud = pud_offset(p4d, address);
4249 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
4250 goto out;
4251
4252 pmd = pmd_offset(pud, address);
4253 VM_BUG_ON(pmd_trans_huge(*pmd));
4254
4255 if (pmd_huge(*pmd)) {
4256 if (!pmdpp)
4257 goto out;
4258
4259 if (start && end) {
4260 *start = address & PMD_MASK;
4261 *end = *start + PMD_SIZE;
4262 mmu_notifier_invalidate_range_start(mm, *start, *end);
4263 }
4264 *ptlp = pmd_lock(mm, pmd);
4265 if (pmd_huge(*pmd)) {
4266 *pmdpp = pmd;
4267 return 0;
4268 }
4269 spin_unlock(*ptlp);
4270 if (start && end)
4271 mmu_notifier_invalidate_range_end(mm, *start, *end);
4272 }
4273
4274 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
4275 goto out;
4276
4277 if (start && end) {
4278 *start = address & PAGE_MASK;
4279 *end = *start + PAGE_SIZE;
4280 mmu_notifier_invalidate_range_start(mm, *start, *end);
4281 }
4282 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
4283 if (!pte_present(*ptep))
4284 goto unlock;
4285 *ptepp = ptep;
4286 return 0;
4287unlock:
4288 pte_unmap_unlock(ptep, *ptlp);
4289 if (start && end)
4290 mmu_notifier_invalidate_range_end(mm, *start, *end);
4291out:
4292 return -EINVAL;
4293}
4294
4295static inline int follow_pte(struct mm_struct *mm, unsigned long address,
4296 pte_t **ptepp, spinlock_t **ptlp)
4297{
4298 int res;
4299
4300 /* (void) is needed to make gcc happy */
4301 (void) __cond_lock(*ptlp,
4302 !(res = __follow_pte_pmd(mm, address, NULL, NULL,
4303 ptepp, NULL, ptlp)));
4304 return res;
4305}
4306
4307int follow_pte_pmd(struct mm_struct *mm, unsigned long address,
4308 unsigned long *start, unsigned long *end,
4309 pte_t **ptepp, pmd_t **pmdpp, spinlock_t **ptlp)
4310{
4311 int res;
4312
4313 /* (void) is needed to make gcc happy */
4314 (void) __cond_lock(*ptlp,
4315 !(res = __follow_pte_pmd(mm, address, start, end,
4316 ptepp, pmdpp, ptlp)));
4317 return res;
4318}
4319EXPORT_SYMBOL(follow_pte_pmd);
4320
4321/**
4322 * follow_pfn - look up PFN at a user virtual address
4323 * @vma: memory mapping
4324 * @address: user virtual address
4325 * @pfn: location to store found PFN
4326 *
4327 * Only IO mappings and raw PFN mappings are allowed.
4328 *
4329 * Returns zero and the pfn at @pfn on success, -ve otherwise.
4330 */
4331int follow_pfn(struct vm_area_struct *vma, unsigned long address,
4332 unsigned long *pfn)
4333{
4334 int ret = -EINVAL;
4335 spinlock_t *ptl;
4336 pte_t *ptep;
4337
4338 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4339 return ret;
4340
4341 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
4342 if (ret)
4343 return ret;
4344 *pfn = pte_pfn(*ptep);
4345 pte_unmap_unlock(ptep, ptl);
4346 return 0;
4347}
4348EXPORT_SYMBOL(follow_pfn);
4349
4350#ifdef CONFIG_HAVE_IOREMAP_PROT
4351int follow_phys(struct vm_area_struct *vma,
4352 unsigned long address, unsigned int flags,
4353 unsigned long *prot, resource_size_t *phys)
4354{
4355 int ret = -EINVAL;
4356 pte_t *ptep, pte;
4357 spinlock_t *ptl;
4358
4359 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4360 goto out;
4361
4362 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
4363 goto out;
4364 pte = *ptep;
4365
4366 if ((flags & FOLL_WRITE) && !pte_write(pte))
4367 goto unlock;
4368
4369 *prot = pgprot_val(pte_pgprot(pte));
4370 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
4371
4372 ret = 0;
4373unlock:
4374 pte_unmap_unlock(ptep, ptl);
4375out:
4376 return ret;
4377}
4378
4379int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
4380 void *buf, int len, int write)
4381{
4382 resource_size_t phys_addr;
4383 unsigned long prot = 0;
4384 void __iomem *maddr;
4385 int offset = addr & (PAGE_SIZE-1);
4386
4387 if (follow_phys(vma, addr, write, &prot, &phys_addr))
4388 return -EINVAL;
4389
4390 maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
4391 if (write)
4392 memcpy_toio(maddr + offset, buf, len);
4393 else
4394 memcpy_fromio(buf, maddr + offset, len);
4395 iounmap(maddr);
4396
4397 return len;
4398}
4399EXPORT_SYMBOL_GPL(generic_access_phys);
4400#endif
4401
4402/*
4403 * Access another process' address space as given in mm. If non-NULL, use the
4404 * given task for page fault accounting.
4405 */
4406int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
4407 unsigned long addr, void *buf, int len, unsigned int gup_flags)
4408{
4409 struct vm_area_struct *vma;
4410 void *old_buf = buf;
4411 int write = gup_flags & FOLL_WRITE;
4412
4413 down_read(&mm->mmap_sem);
4414 /* ignore errors, just check how much was successfully transferred */
4415 while (len) {
4416 int bytes, ret, offset;
4417 void *maddr;
4418 struct page *page = NULL;
4419
4420 ret = get_user_pages_remote(tsk, mm, addr, 1,
4421 gup_flags, &page, &vma, NULL);
4422 if (ret <= 0) {
4423#ifndef CONFIG_HAVE_IOREMAP_PROT
4424 break;
4425#else
4426 /*
4427 * Check if this is a VM_IO | VM_PFNMAP VMA, which
4428 * we can access using slightly different code.
4429 */
4430 vma = find_vma(mm, addr);
4431 if (!vma || vma->vm_start > addr)
4432 break;
4433 if (vma->vm_ops && vma->vm_ops->access)
4434 ret = vma->vm_ops->access(vma, addr, buf,
4435 len, write);
4436 if (ret <= 0)
4437 break;
4438 bytes = ret;
4439#endif
4440 } else {
4441 bytes = len;
4442 offset = addr & (PAGE_SIZE-1);
4443 if (bytes > PAGE_SIZE-offset)
4444 bytes = PAGE_SIZE-offset;
4445
4446 maddr = kmap(page);
4447 if (write) {
4448 copy_to_user_page(vma, page, addr,
4449 maddr + offset, buf, bytes);
4450 set_page_dirty_lock(page);
4451 } else {
4452 copy_from_user_page(vma, page, addr,
4453 buf, maddr + offset, bytes);
4454 }
4455 kunmap(page);
4456 put_page(page);
4457 }
4458 len -= bytes;
4459 buf += bytes;
4460 addr += bytes;
4461 }
4462 up_read(&mm->mmap_sem);
4463
4464 return buf - old_buf;
4465}
4466
4467/**
4468 * access_remote_vm - access another process' address space
4469 * @mm: the mm_struct of the target address space
4470 * @addr: start address to access
4471 * @buf: source or destination buffer
4472 * @len: number of bytes to transfer
4473 * @gup_flags: flags modifying lookup behaviour
4474 *
4475 * The caller must hold a reference on @mm.
4476 */
4477int access_remote_vm(struct mm_struct *mm, unsigned long addr,
4478 void *buf, int len, unsigned int gup_flags)
4479{
4480 return __access_remote_vm(NULL, mm, addr, buf, len, gup_flags);
4481}
4482
4483/*
4484 * Access another process' address space.
4485 * Source/target buffer must be kernel space,
4486 * Do not walk the page table directly, use get_user_pages
4487 */
4488int access_process_vm(struct task_struct *tsk, unsigned long addr,
4489 void *buf, int len, unsigned int gup_flags)
4490{
4491 struct mm_struct *mm;
4492 int ret;
4493
4494 mm = get_task_mm(tsk);
4495 if (!mm)
4496 return 0;
4497
4498 ret = __access_remote_vm(tsk, mm, addr, buf, len, gup_flags);
4499
4500 mmput(mm);
4501
4502 return ret;
4503}
4504EXPORT_SYMBOL_GPL(access_process_vm);
4505
4506/*
4507 * Print the name of a VMA.
4508 */
4509void print_vma_addr(char *prefix, unsigned long ip)
4510{
4511 struct mm_struct *mm = current->mm;
4512 struct vm_area_struct *vma;
4513
4514 /*
4515 * we might be running from an atomic context so we cannot sleep
4516 */
4517 if (!down_read_trylock(&mm->mmap_sem))
4518 return;
4519
4520 vma = find_vma(mm, ip);
4521 if (vma && vma->vm_file) {
4522 struct file *f = vma->vm_file;
4523 char *buf = (char *)__get_free_page(GFP_NOWAIT);
4524 if (buf) {
4525 char *p;
4526
4527 p = file_path(f, buf, PAGE_SIZE);
4528 if (IS_ERR(p))
4529 p = "?";
4530 printk("%s%s[%lx+%lx]", prefix, kbasename(p),
4531 vma->vm_start,
4532 vma->vm_end - vma->vm_start);
4533 free_page((unsigned long)buf);
4534 }
4535 }
4536 up_read(&mm->mmap_sem);
4537}
4538
4539#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4540void __might_fault(const char *file, int line)
4541{
4542 /*
4543 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
4544 * holding the mmap_sem, this is safe because kernel memory doesn't
4545 * get paged out, therefore we'll never actually fault, and the
4546 * below annotations will generate false positives.
4547 */
4548 if (uaccess_kernel())
4549 return;
4550 if (pagefault_disabled())
4551 return;
4552 __might_sleep(file, line, 0);
4553#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4554 if (current->mm)
4555 might_lock_read(¤t->mm->mmap_sem);
4556#endif
4557}
4558EXPORT_SYMBOL(__might_fault);
4559#endif
4560
4561#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
4562static void clear_gigantic_page(struct page *page,
4563 unsigned long addr,
4564 unsigned int pages_per_huge_page)
4565{
4566 int i;
4567 struct page *p = page;
4568
4569 might_sleep();
4570 for (i = 0; i < pages_per_huge_page;
4571 i++, p = mem_map_next(p, page, i)) {
4572 cond_resched();
4573 clear_user_highpage(p, addr + i * PAGE_SIZE);
4574 }
4575}
4576void clear_huge_page(struct page *page,
4577 unsigned long addr_hint, unsigned int pages_per_huge_page)
4578{
4579 int i, n, base, l;
4580 unsigned long addr = addr_hint &
4581 ~(((unsigned long)pages_per_huge_page << PAGE_SHIFT) - 1);
4582
4583 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4584 clear_gigantic_page(page, addr, pages_per_huge_page);
4585 return;
4586 }
4587
4588 /* Clear sub-page to access last to keep its cache lines hot */
4589 might_sleep();
4590 n = (addr_hint - addr) / PAGE_SIZE;
4591 if (2 * n <= pages_per_huge_page) {
4592 /* If sub-page to access in first half of huge page */
4593 base = 0;
4594 l = n;
4595 /* Clear sub-pages at the end of huge page */
4596 for (i = pages_per_huge_page - 1; i >= 2 * n; i--) {
4597 cond_resched();
4598 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
4599 }
4600 } else {
4601 /* If sub-page to access in second half of huge page */
4602 base = pages_per_huge_page - 2 * (pages_per_huge_page - n);
4603 l = pages_per_huge_page - n;
4604 /* Clear sub-pages at the begin of huge page */
4605 for (i = 0; i < base; i++) {
4606 cond_resched();
4607 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
4608 }
4609 }
4610 /*
4611 * Clear remaining sub-pages in left-right-left-right pattern
4612 * towards the sub-page to access
4613 */
4614 for (i = 0; i < l; i++) {
4615 int left_idx = base + i;
4616 int right_idx = base + 2 * l - 1 - i;
4617
4618 cond_resched();
4619 clear_user_highpage(page + left_idx,
4620 addr + left_idx * PAGE_SIZE);
4621 cond_resched();
4622 clear_user_highpage(page + right_idx,
4623 addr + right_idx * PAGE_SIZE);
4624 }
4625}
4626
4627static void copy_user_gigantic_page(struct page *dst, struct page *src,
4628 unsigned long addr,
4629 struct vm_area_struct *vma,
4630 unsigned int pages_per_huge_page)
4631{
4632 int i;
4633 struct page *dst_base = dst;
4634 struct page *src_base = src;
4635
4636 for (i = 0; i < pages_per_huge_page; ) {
4637 cond_resched();
4638 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
4639
4640 i++;
4641 dst = mem_map_next(dst, dst_base, i);
4642 src = mem_map_next(src, src_base, i);
4643 }
4644}
4645
4646void copy_user_huge_page(struct page *dst, struct page *src,
4647 unsigned long addr, struct vm_area_struct *vma,
4648 unsigned int pages_per_huge_page)
4649{
4650 int i;
4651
4652 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4653 copy_user_gigantic_page(dst, src, addr, vma,
4654 pages_per_huge_page);
4655 return;
4656 }
4657
4658 might_sleep();
4659 for (i = 0; i < pages_per_huge_page; i++) {
4660 cond_resched();
4661 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
4662 }
4663}
4664
4665long copy_huge_page_from_user(struct page *dst_page,
4666 const void __user *usr_src,
4667 unsigned int pages_per_huge_page,
4668 bool allow_pagefault)
4669{
4670 void *src = (void *)usr_src;
4671 void *page_kaddr;
4672 unsigned long i, rc = 0;
4673 unsigned long ret_val = pages_per_huge_page * PAGE_SIZE;
4674
4675 for (i = 0; i < pages_per_huge_page; i++) {
4676 if (allow_pagefault)
4677 page_kaddr = kmap(dst_page + i);
4678 else
4679 page_kaddr = kmap_atomic(dst_page + i);
4680 rc = copy_from_user(page_kaddr,
4681 (const void __user *)(src + i * PAGE_SIZE),
4682 PAGE_SIZE);
4683 if (allow_pagefault)
4684 kunmap(dst_page + i);
4685 else
4686 kunmap_atomic(page_kaddr);
4687
4688 ret_val -= (PAGE_SIZE - rc);
4689 if (rc)
4690 break;
4691
4692 cond_resched();
4693 }
4694 return ret_val;
4695}
4696#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
4697
4698#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
4699
4700static struct kmem_cache *page_ptl_cachep;
4701
4702void __init ptlock_cache_init(void)
4703{
4704 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
4705 SLAB_PANIC, NULL);
4706}
4707
4708bool ptlock_alloc(struct page *page)
4709{
4710 spinlock_t *ptl;
4711
4712 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
4713 if (!ptl)
4714 return false;
4715 page->ptl = ptl;
4716 return true;
4717}
4718
4719void ptlock_free(struct page *page)
4720{
4721 kmem_cache_free(page_ptl_cachep, page->ptl);
4722}
4723#endif
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/mm/memory.c
4 *
5 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
6 */
7
8/*
9 * demand-loading started 01.12.91 - seems it is high on the list of
10 * things wanted, and it should be easy to implement. - Linus
11 */
12
13/*
14 * Ok, demand-loading was easy, shared pages a little bit tricker. Shared
15 * pages started 02.12.91, seems to work. - Linus.
16 *
17 * Tested sharing by executing about 30 /bin/sh: under the old kernel it
18 * would have taken more than the 6M I have free, but it worked well as
19 * far as I could see.
20 *
21 * Also corrected some "invalidate()"s - I wasn't doing enough of them.
22 */
23
24/*
25 * Real VM (paging to/from disk) started 18.12.91. Much more work and
26 * thought has to go into this. Oh, well..
27 * 19.12.91 - works, somewhat. Sometimes I get faults, don't know why.
28 * Found it. Everything seems to work now.
29 * 20.12.91 - Ok, making the swap-device changeable like the root.
30 */
31
32/*
33 * 05.04.94 - Multi-page memory management added for v1.1.
34 * Idea by Alex Bligh (alex@cconcepts.co.uk)
35 *
36 * 16.07.99 - Support of BIGMEM added by Gerhard Wichert, Siemens AG
37 * (Gerhard.Wichert@pdb.siemens.de)
38 *
39 * Aug/Sep 2004 Changed to four level page tables (Andi Kleen)
40 */
41
42#include <linux/kernel_stat.h>
43#include <linux/mm.h>
44#include <linux/mm_inline.h>
45#include <linux/sched/mm.h>
46#include <linux/sched/numa_balancing.h>
47#include <linux/sched/task.h>
48#include <linux/hugetlb.h>
49#include <linux/mman.h>
50#include <linux/swap.h>
51#include <linux/highmem.h>
52#include <linux/pagemap.h>
53#include <linux/memremap.h>
54#include <linux/kmsan.h>
55#include <linux/ksm.h>
56#include <linux/rmap.h>
57#include <linux/export.h>
58#include <linux/delayacct.h>
59#include <linux/init.h>
60#include <linux/pfn_t.h>
61#include <linux/writeback.h>
62#include <linux/memcontrol.h>
63#include <linux/mmu_notifier.h>
64#include <linux/swapops.h>
65#include <linux/elf.h>
66#include <linux/gfp.h>
67#include <linux/migrate.h>
68#include <linux/string.h>
69#include <linux/memory-tiers.h>
70#include <linux/debugfs.h>
71#include <linux/userfaultfd_k.h>
72#include <linux/dax.h>
73#include <linux/oom.h>
74#include <linux/numa.h>
75#include <linux/perf_event.h>
76#include <linux/ptrace.h>
77#include <linux/vmalloc.h>
78#include <linux/sched/sysctl.h>
79
80#include <trace/events/kmem.h>
81
82#include <asm/io.h>
83#include <asm/mmu_context.h>
84#include <asm/pgalloc.h>
85#include <linux/uaccess.h>
86#include <asm/tlb.h>
87#include <asm/tlbflush.h>
88
89#include "pgalloc-track.h"
90#include "internal.h"
91#include "swap.h"
92
93#if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST)
94#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
95#endif
96
97#ifndef CONFIG_NUMA
98unsigned long max_mapnr;
99EXPORT_SYMBOL(max_mapnr);
100
101struct page *mem_map;
102EXPORT_SYMBOL(mem_map);
103#endif
104
105static vm_fault_t do_fault(struct vm_fault *vmf);
106static vm_fault_t do_anonymous_page(struct vm_fault *vmf);
107static bool vmf_pte_changed(struct vm_fault *vmf);
108
109/*
110 * Return true if the original pte was a uffd-wp pte marker (so the pte was
111 * wr-protected).
112 */
113static __always_inline bool vmf_orig_pte_uffd_wp(struct vm_fault *vmf)
114{
115 if (!userfaultfd_wp(vmf->vma))
116 return false;
117 if (!(vmf->flags & FAULT_FLAG_ORIG_PTE_VALID))
118 return false;
119
120 return pte_marker_uffd_wp(vmf->orig_pte);
121}
122
123/*
124 * A number of key systems in x86 including ioremap() rely on the assumption
125 * that high_memory defines the upper bound on direct map memory, then end
126 * of ZONE_NORMAL.
127 */
128void *high_memory;
129EXPORT_SYMBOL(high_memory);
130
131/*
132 * Randomize the address space (stacks, mmaps, brk, etc.).
133 *
134 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
135 * as ancient (libc5 based) binaries can segfault. )
136 */
137int randomize_va_space __read_mostly =
138#ifdef CONFIG_COMPAT_BRK
139 1;
140#else
141 2;
142#endif
143
144#ifndef arch_wants_old_prefaulted_pte
145static inline bool arch_wants_old_prefaulted_pte(void)
146{
147 /*
148 * Transitioning a PTE from 'old' to 'young' can be expensive on
149 * some architectures, even if it's performed in hardware. By
150 * default, "false" means prefaulted entries will be 'young'.
151 */
152 return false;
153}
154#endif
155
156static int __init disable_randmaps(char *s)
157{
158 randomize_va_space = 0;
159 return 1;
160}
161__setup("norandmaps", disable_randmaps);
162
163unsigned long zero_pfn __read_mostly;
164EXPORT_SYMBOL(zero_pfn);
165
166unsigned long highest_memmap_pfn __read_mostly;
167
168/*
169 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
170 */
171static int __init init_zero_pfn(void)
172{
173 zero_pfn = page_to_pfn(ZERO_PAGE(0));
174 return 0;
175}
176early_initcall(init_zero_pfn);
177
178void mm_trace_rss_stat(struct mm_struct *mm, int member)
179{
180 trace_rss_stat(mm, member);
181}
182
183/*
184 * Note: this doesn't free the actual pages themselves. That
185 * has been handled earlier when unmapping all the memory regions.
186 */
187static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
188 unsigned long addr)
189{
190 pgtable_t token = pmd_pgtable(*pmd);
191 pmd_clear(pmd);
192 pte_free_tlb(tlb, token, addr);
193 mm_dec_nr_ptes(tlb->mm);
194}
195
196static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
197 unsigned long addr, unsigned long end,
198 unsigned long floor, unsigned long ceiling)
199{
200 pmd_t *pmd;
201 unsigned long next;
202 unsigned long start;
203
204 start = addr;
205 pmd = pmd_offset(pud, addr);
206 do {
207 next = pmd_addr_end(addr, end);
208 if (pmd_none_or_clear_bad(pmd))
209 continue;
210 free_pte_range(tlb, pmd, addr);
211 } while (pmd++, addr = next, addr != end);
212
213 start &= PUD_MASK;
214 if (start < floor)
215 return;
216 if (ceiling) {
217 ceiling &= PUD_MASK;
218 if (!ceiling)
219 return;
220 }
221 if (end - 1 > ceiling - 1)
222 return;
223
224 pmd = pmd_offset(pud, start);
225 pud_clear(pud);
226 pmd_free_tlb(tlb, pmd, start);
227 mm_dec_nr_pmds(tlb->mm);
228}
229
230static inline void free_pud_range(struct mmu_gather *tlb, p4d_t *p4d,
231 unsigned long addr, unsigned long end,
232 unsigned long floor, unsigned long ceiling)
233{
234 pud_t *pud;
235 unsigned long next;
236 unsigned long start;
237
238 start = addr;
239 pud = pud_offset(p4d, addr);
240 do {
241 next = pud_addr_end(addr, end);
242 if (pud_none_or_clear_bad(pud))
243 continue;
244 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
245 } while (pud++, addr = next, addr != end);
246
247 start &= P4D_MASK;
248 if (start < floor)
249 return;
250 if (ceiling) {
251 ceiling &= P4D_MASK;
252 if (!ceiling)
253 return;
254 }
255 if (end - 1 > ceiling - 1)
256 return;
257
258 pud = pud_offset(p4d, start);
259 p4d_clear(p4d);
260 pud_free_tlb(tlb, pud, start);
261 mm_dec_nr_puds(tlb->mm);
262}
263
264static inline void free_p4d_range(struct mmu_gather *tlb, pgd_t *pgd,
265 unsigned long addr, unsigned long end,
266 unsigned long floor, unsigned long ceiling)
267{
268 p4d_t *p4d;
269 unsigned long next;
270 unsigned long start;
271
272 start = addr;
273 p4d = p4d_offset(pgd, addr);
274 do {
275 next = p4d_addr_end(addr, end);
276 if (p4d_none_or_clear_bad(p4d))
277 continue;
278 free_pud_range(tlb, p4d, addr, next, floor, ceiling);
279 } while (p4d++, addr = next, addr != end);
280
281 start &= PGDIR_MASK;
282 if (start < floor)
283 return;
284 if (ceiling) {
285 ceiling &= PGDIR_MASK;
286 if (!ceiling)
287 return;
288 }
289 if (end - 1 > ceiling - 1)
290 return;
291
292 p4d = p4d_offset(pgd, start);
293 pgd_clear(pgd);
294 p4d_free_tlb(tlb, p4d, start);
295}
296
297/*
298 * This function frees user-level page tables of a process.
299 */
300void free_pgd_range(struct mmu_gather *tlb,
301 unsigned long addr, unsigned long end,
302 unsigned long floor, unsigned long ceiling)
303{
304 pgd_t *pgd;
305 unsigned long next;
306
307 /*
308 * The next few lines have given us lots of grief...
309 *
310 * Why are we testing PMD* at this top level? Because often
311 * there will be no work to do at all, and we'd prefer not to
312 * go all the way down to the bottom just to discover that.
313 *
314 * Why all these "- 1"s? Because 0 represents both the bottom
315 * of the address space and the top of it (using -1 for the
316 * top wouldn't help much: the masks would do the wrong thing).
317 * The rule is that addr 0 and floor 0 refer to the bottom of
318 * the address space, but end 0 and ceiling 0 refer to the top
319 * Comparisons need to use "end - 1" and "ceiling - 1" (though
320 * that end 0 case should be mythical).
321 *
322 * Wherever addr is brought up or ceiling brought down, we must
323 * be careful to reject "the opposite 0" before it confuses the
324 * subsequent tests. But what about where end is brought down
325 * by PMD_SIZE below? no, end can't go down to 0 there.
326 *
327 * Whereas we round start (addr) and ceiling down, by different
328 * masks at different levels, in order to test whether a table
329 * now has no other vmas using it, so can be freed, we don't
330 * bother to round floor or end up - the tests don't need that.
331 */
332
333 addr &= PMD_MASK;
334 if (addr < floor) {
335 addr += PMD_SIZE;
336 if (!addr)
337 return;
338 }
339 if (ceiling) {
340 ceiling &= PMD_MASK;
341 if (!ceiling)
342 return;
343 }
344 if (end - 1 > ceiling - 1)
345 end -= PMD_SIZE;
346 if (addr > end - 1)
347 return;
348 /*
349 * We add page table cache pages with PAGE_SIZE,
350 * (see pte_free_tlb()), flush the tlb if we need
351 */
352 tlb_change_page_size(tlb, PAGE_SIZE);
353 pgd = pgd_offset(tlb->mm, addr);
354 do {
355 next = pgd_addr_end(addr, end);
356 if (pgd_none_or_clear_bad(pgd))
357 continue;
358 free_p4d_range(tlb, pgd, addr, next, floor, ceiling);
359 } while (pgd++, addr = next, addr != end);
360}
361
362void free_pgtables(struct mmu_gather *tlb, struct ma_state *mas,
363 struct vm_area_struct *vma, unsigned long floor,
364 unsigned long ceiling, bool mm_wr_locked)
365{
366 struct unlink_vma_file_batch vb;
367
368 do {
369 unsigned long addr = vma->vm_start;
370 struct vm_area_struct *next;
371
372 /*
373 * Note: USER_PGTABLES_CEILING may be passed as ceiling and may
374 * be 0. This will underflow and is okay.
375 */
376 next = mas_find(mas, ceiling - 1);
377 if (unlikely(xa_is_zero(next)))
378 next = NULL;
379
380 /*
381 * Hide vma from rmap and truncate_pagecache before freeing
382 * pgtables
383 */
384 if (mm_wr_locked)
385 vma_start_write(vma);
386 unlink_anon_vmas(vma);
387
388 if (is_vm_hugetlb_page(vma)) {
389 unlink_file_vma(vma);
390 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
391 floor, next ? next->vm_start : ceiling);
392 } else {
393 unlink_file_vma_batch_init(&vb);
394 unlink_file_vma_batch_add(&vb, vma);
395
396 /*
397 * Optimization: gather nearby vmas into one call down
398 */
399 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
400 && !is_vm_hugetlb_page(next)) {
401 vma = next;
402 next = mas_find(mas, ceiling - 1);
403 if (unlikely(xa_is_zero(next)))
404 next = NULL;
405 if (mm_wr_locked)
406 vma_start_write(vma);
407 unlink_anon_vmas(vma);
408 unlink_file_vma_batch_add(&vb, vma);
409 }
410 unlink_file_vma_batch_final(&vb);
411 free_pgd_range(tlb, addr, vma->vm_end,
412 floor, next ? next->vm_start : ceiling);
413 }
414 vma = next;
415 } while (vma);
416}
417
418void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte)
419{
420 spinlock_t *ptl = pmd_lock(mm, pmd);
421
422 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
423 mm_inc_nr_ptes(mm);
424 /*
425 * Ensure all pte setup (eg. pte page lock and page clearing) are
426 * visible before the pte is made visible to other CPUs by being
427 * put into page tables.
428 *
429 * The other side of the story is the pointer chasing in the page
430 * table walking code (when walking the page table without locking;
431 * ie. most of the time). Fortunately, these data accesses consist
432 * of a chain of data-dependent loads, meaning most CPUs (alpha
433 * being the notable exception) will already guarantee loads are
434 * seen in-order. See the alpha page table accessors for the
435 * smp_rmb() barriers in page table walking code.
436 */
437 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
438 pmd_populate(mm, pmd, *pte);
439 *pte = NULL;
440 }
441 spin_unlock(ptl);
442}
443
444int __pte_alloc(struct mm_struct *mm, pmd_t *pmd)
445{
446 pgtable_t new = pte_alloc_one(mm);
447 if (!new)
448 return -ENOMEM;
449
450 pmd_install(mm, pmd, &new);
451 if (new)
452 pte_free(mm, new);
453 return 0;
454}
455
456int __pte_alloc_kernel(pmd_t *pmd)
457{
458 pte_t *new = pte_alloc_one_kernel(&init_mm);
459 if (!new)
460 return -ENOMEM;
461
462 spin_lock(&init_mm.page_table_lock);
463 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
464 smp_wmb(); /* See comment in pmd_install() */
465 pmd_populate_kernel(&init_mm, pmd, new);
466 new = NULL;
467 }
468 spin_unlock(&init_mm.page_table_lock);
469 if (new)
470 pte_free_kernel(&init_mm, new);
471 return 0;
472}
473
474static inline void init_rss_vec(int *rss)
475{
476 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
477}
478
479static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
480{
481 int i;
482
483 for (i = 0; i < NR_MM_COUNTERS; i++)
484 if (rss[i])
485 add_mm_counter(mm, i, rss[i]);
486}
487
488/*
489 * This function is called to print an error when a bad pte
490 * is found. For example, we might have a PFN-mapped pte in
491 * a region that doesn't allow it.
492 *
493 * The calling function must still handle the error.
494 */
495static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
496 pte_t pte, struct page *page)
497{
498 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
499 p4d_t *p4d = p4d_offset(pgd, addr);
500 pud_t *pud = pud_offset(p4d, addr);
501 pmd_t *pmd = pmd_offset(pud, addr);
502 struct address_space *mapping;
503 pgoff_t index;
504 static unsigned long resume;
505 static unsigned long nr_shown;
506 static unsigned long nr_unshown;
507
508 /*
509 * Allow a burst of 60 reports, then keep quiet for that minute;
510 * or allow a steady drip of one report per second.
511 */
512 if (nr_shown == 60) {
513 if (time_before(jiffies, resume)) {
514 nr_unshown++;
515 return;
516 }
517 if (nr_unshown) {
518 pr_alert("BUG: Bad page map: %lu messages suppressed\n",
519 nr_unshown);
520 nr_unshown = 0;
521 }
522 nr_shown = 0;
523 }
524 if (nr_shown++ == 0)
525 resume = jiffies + 60 * HZ;
526
527 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
528 index = linear_page_index(vma, addr);
529
530 pr_alert("BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
531 current->comm,
532 (long long)pte_val(pte), (long long)pmd_val(*pmd));
533 if (page)
534 dump_page(page, "bad pte");
535 pr_alert("addr:%px vm_flags:%08lx anon_vma:%px mapping:%px index:%lx\n",
536 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
537 pr_alert("file:%pD fault:%ps mmap:%ps read_folio:%ps\n",
538 vma->vm_file,
539 vma->vm_ops ? vma->vm_ops->fault : NULL,
540 vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
541 mapping ? mapping->a_ops->read_folio : NULL);
542 dump_stack();
543 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
544}
545
546/*
547 * vm_normal_page -- This function gets the "struct page" associated with a pte.
548 *
549 * "Special" mappings do not wish to be associated with a "struct page" (either
550 * it doesn't exist, or it exists but they don't want to touch it). In this
551 * case, NULL is returned here. "Normal" mappings do have a struct page.
552 *
553 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
554 * pte bit, in which case this function is trivial. Secondly, an architecture
555 * may not have a spare pte bit, which requires a more complicated scheme,
556 * described below.
557 *
558 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
559 * special mapping (even if there are underlying and valid "struct pages").
560 * COWed pages of a VM_PFNMAP are always normal.
561 *
562 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
563 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
564 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
565 * mapping will always honor the rule
566 *
567 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
568 *
569 * And for normal mappings this is false.
570 *
571 * This restricts such mappings to be a linear translation from virtual address
572 * to pfn. To get around this restriction, we allow arbitrary mappings so long
573 * as the vma is not a COW mapping; in that case, we know that all ptes are
574 * special (because none can have been COWed).
575 *
576 *
577 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
578 *
579 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
580 * page" backing, however the difference is that _all_ pages with a struct
581 * page (that is, those where pfn_valid is true) are refcounted and considered
582 * normal pages by the VM. The only exception are zeropages, which are
583 * *never* refcounted.
584 *
585 * The disadvantage is that pages are refcounted (which can be slower and
586 * simply not an option for some PFNMAP users). The advantage is that we
587 * don't have to follow the strict linearity rule of PFNMAP mappings in
588 * order to support COWable mappings.
589 *
590 */
591struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
592 pte_t pte)
593{
594 unsigned long pfn = pte_pfn(pte);
595
596 if (IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL)) {
597 if (likely(!pte_special(pte)))
598 goto check_pfn;
599 if (vma->vm_ops && vma->vm_ops->find_special_page)
600 return vma->vm_ops->find_special_page(vma, addr);
601 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
602 return NULL;
603 if (is_zero_pfn(pfn))
604 return NULL;
605 if (pte_devmap(pte))
606 /*
607 * NOTE: New users of ZONE_DEVICE will not set pte_devmap()
608 * and will have refcounts incremented on their struct pages
609 * when they are inserted into PTEs, thus they are safe to
610 * return here. Legacy ZONE_DEVICE pages that set pte_devmap()
611 * do not have refcounts. Example of legacy ZONE_DEVICE is
612 * MEMORY_DEVICE_FS_DAX type in pmem or virtio_fs drivers.
613 */
614 return NULL;
615
616 print_bad_pte(vma, addr, pte, NULL);
617 return NULL;
618 }
619
620 /* !CONFIG_ARCH_HAS_PTE_SPECIAL case follows: */
621
622 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
623 if (vma->vm_flags & VM_MIXEDMAP) {
624 if (!pfn_valid(pfn))
625 return NULL;
626 if (is_zero_pfn(pfn))
627 return NULL;
628 goto out;
629 } else {
630 unsigned long off;
631 off = (addr - vma->vm_start) >> PAGE_SHIFT;
632 if (pfn == vma->vm_pgoff + off)
633 return NULL;
634 if (!is_cow_mapping(vma->vm_flags))
635 return NULL;
636 }
637 }
638
639 if (is_zero_pfn(pfn))
640 return NULL;
641
642check_pfn:
643 if (unlikely(pfn > highest_memmap_pfn)) {
644 print_bad_pte(vma, addr, pte, NULL);
645 return NULL;
646 }
647
648 /*
649 * NOTE! We still have PageReserved() pages in the page tables.
650 * eg. VDSO mappings can cause them to exist.
651 */
652out:
653 VM_WARN_ON_ONCE(is_zero_pfn(pfn));
654 return pfn_to_page(pfn);
655}
656
657struct folio *vm_normal_folio(struct vm_area_struct *vma, unsigned long addr,
658 pte_t pte)
659{
660 struct page *page = vm_normal_page(vma, addr, pte);
661
662 if (page)
663 return page_folio(page);
664 return NULL;
665}
666
667#ifdef CONFIG_PGTABLE_HAS_HUGE_LEAVES
668struct page *vm_normal_page_pmd(struct vm_area_struct *vma, unsigned long addr,
669 pmd_t pmd)
670{
671 unsigned long pfn = pmd_pfn(pmd);
672
673 /* Currently it's only used for huge pfnmaps */
674 if (unlikely(pmd_special(pmd)))
675 return NULL;
676
677 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
678 if (vma->vm_flags & VM_MIXEDMAP) {
679 if (!pfn_valid(pfn))
680 return NULL;
681 goto out;
682 } else {
683 unsigned long off;
684 off = (addr - vma->vm_start) >> PAGE_SHIFT;
685 if (pfn == vma->vm_pgoff + off)
686 return NULL;
687 if (!is_cow_mapping(vma->vm_flags))
688 return NULL;
689 }
690 }
691
692 if (pmd_devmap(pmd))
693 return NULL;
694 if (is_huge_zero_pmd(pmd))
695 return NULL;
696 if (unlikely(pfn > highest_memmap_pfn))
697 return NULL;
698
699 /*
700 * NOTE! We still have PageReserved() pages in the page tables.
701 * eg. VDSO mappings can cause them to exist.
702 */
703out:
704 return pfn_to_page(pfn);
705}
706
707struct folio *vm_normal_folio_pmd(struct vm_area_struct *vma,
708 unsigned long addr, pmd_t pmd)
709{
710 struct page *page = vm_normal_page_pmd(vma, addr, pmd);
711
712 if (page)
713 return page_folio(page);
714 return NULL;
715}
716#endif
717
718static void restore_exclusive_pte(struct vm_area_struct *vma,
719 struct page *page, unsigned long address,
720 pte_t *ptep)
721{
722 struct folio *folio = page_folio(page);
723 pte_t orig_pte;
724 pte_t pte;
725 swp_entry_t entry;
726
727 orig_pte = ptep_get(ptep);
728 pte = pte_mkold(mk_pte(page, READ_ONCE(vma->vm_page_prot)));
729 if (pte_swp_soft_dirty(orig_pte))
730 pte = pte_mksoft_dirty(pte);
731
732 entry = pte_to_swp_entry(orig_pte);
733 if (pte_swp_uffd_wp(orig_pte))
734 pte = pte_mkuffd_wp(pte);
735 else if (is_writable_device_exclusive_entry(entry))
736 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
737
738 VM_BUG_ON_FOLIO(pte_write(pte) && (!folio_test_anon(folio) &&
739 PageAnonExclusive(page)), folio);
740
741 /*
742 * No need to take a page reference as one was already
743 * created when the swap entry was made.
744 */
745 if (folio_test_anon(folio))
746 folio_add_anon_rmap_pte(folio, page, vma, address, RMAP_NONE);
747 else
748 /*
749 * Currently device exclusive access only supports anonymous
750 * memory so the entry shouldn't point to a filebacked page.
751 */
752 WARN_ON_ONCE(1);
753
754 set_pte_at(vma->vm_mm, address, ptep, pte);
755
756 /*
757 * No need to invalidate - it was non-present before. However
758 * secondary CPUs may have mappings that need invalidating.
759 */
760 update_mmu_cache(vma, address, ptep);
761}
762
763/*
764 * Tries to restore an exclusive pte if the page lock can be acquired without
765 * sleeping.
766 */
767static int
768try_restore_exclusive_pte(pte_t *src_pte, struct vm_area_struct *vma,
769 unsigned long addr)
770{
771 swp_entry_t entry = pte_to_swp_entry(ptep_get(src_pte));
772 struct page *page = pfn_swap_entry_to_page(entry);
773
774 if (trylock_page(page)) {
775 restore_exclusive_pte(vma, page, addr, src_pte);
776 unlock_page(page);
777 return 0;
778 }
779
780 return -EBUSY;
781}
782
783/*
784 * copy one vm_area from one task to the other. Assumes the page tables
785 * already present in the new task to be cleared in the whole range
786 * covered by this vma.
787 */
788
789static unsigned long
790copy_nonpresent_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
791 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *dst_vma,
792 struct vm_area_struct *src_vma, unsigned long addr, int *rss)
793{
794 unsigned long vm_flags = dst_vma->vm_flags;
795 pte_t orig_pte = ptep_get(src_pte);
796 pte_t pte = orig_pte;
797 struct folio *folio;
798 struct page *page;
799 swp_entry_t entry = pte_to_swp_entry(orig_pte);
800
801 if (likely(!non_swap_entry(entry))) {
802 if (swap_duplicate(entry) < 0)
803 return -EIO;
804
805 /* make sure dst_mm is on swapoff's mmlist. */
806 if (unlikely(list_empty(&dst_mm->mmlist))) {
807 spin_lock(&mmlist_lock);
808 if (list_empty(&dst_mm->mmlist))
809 list_add(&dst_mm->mmlist,
810 &src_mm->mmlist);
811 spin_unlock(&mmlist_lock);
812 }
813 /* Mark the swap entry as shared. */
814 if (pte_swp_exclusive(orig_pte)) {
815 pte = pte_swp_clear_exclusive(orig_pte);
816 set_pte_at(src_mm, addr, src_pte, pte);
817 }
818 rss[MM_SWAPENTS]++;
819 } else if (is_migration_entry(entry)) {
820 folio = pfn_swap_entry_folio(entry);
821
822 rss[mm_counter(folio)]++;
823
824 if (!is_readable_migration_entry(entry) &&
825 is_cow_mapping(vm_flags)) {
826 /*
827 * COW mappings require pages in both parent and child
828 * to be set to read. A previously exclusive entry is
829 * now shared.
830 */
831 entry = make_readable_migration_entry(
832 swp_offset(entry));
833 pte = swp_entry_to_pte(entry);
834 if (pte_swp_soft_dirty(orig_pte))
835 pte = pte_swp_mksoft_dirty(pte);
836 if (pte_swp_uffd_wp(orig_pte))
837 pte = pte_swp_mkuffd_wp(pte);
838 set_pte_at(src_mm, addr, src_pte, pte);
839 }
840 } else if (is_device_private_entry(entry)) {
841 page = pfn_swap_entry_to_page(entry);
842 folio = page_folio(page);
843
844 /*
845 * Update rss count even for unaddressable pages, as
846 * they should treated just like normal pages in this
847 * respect.
848 *
849 * We will likely want to have some new rss counters
850 * for unaddressable pages, at some point. But for now
851 * keep things as they are.
852 */
853 folio_get(folio);
854 rss[mm_counter(folio)]++;
855 /* Cannot fail as these pages cannot get pinned. */
856 folio_try_dup_anon_rmap_pte(folio, page, src_vma);
857
858 /*
859 * We do not preserve soft-dirty information, because so
860 * far, checkpoint/restore is the only feature that
861 * requires that. And checkpoint/restore does not work
862 * when a device driver is involved (you cannot easily
863 * save and restore device driver state).
864 */
865 if (is_writable_device_private_entry(entry) &&
866 is_cow_mapping(vm_flags)) {
867 entry = make_readable_device_private_entry(
868 swp_offset(entry));
869 pte = swp_entry_to_pte(entry);
870 if (pte_swp_uffd_wp(orig_pte))
871 pte = pte_swp_mkuffd_wp(pte);
872 set_pte_at(src_mm, addr, src_pte, pte);
873 }
874 } else if (is_device_exclusive_entry(entry)) {
875 /*
876 * Make device exclusive entries present by restoring the
877 * original entry then copying as for a present pte. Device
878 * exclusive entries currently only support private writable
879 * (ie. COW) mappings.
880 */
881 VM_BUG_ON(!is_cow_mapping(src_vma->vm_flags));
882 if (try_restore_exclusive_pte(src_pte, src_vma, addr))
883 return -EBUSY;
884 return -ENOENT;
885 } else if (is_pte_marker_entry(entry)) {
886 pte_marker marker = copy_pte_marker(entry, dst_vma);
887
888 if (marker)
889 set_pte_at(dst_mm, addr, dst_pte,
890 make_pte_marker(marker));
891 return 0;
892 }
893 if (!userfaultfd_wp(dst_vma))
894 pte = pte_swp_clear_uffd_wp(pte);
895 set_pte_at(dst_mm, addr, dst_pte, pte);
896 return 0;
897}
898
899/*
900 * Copy a present and normal page.
901 *
902 * NOTE! The usual case is that this isn't required;
903 * instead, the caller can just increase the page refcount
904 * and re-use the pte the traditional way.
905 *
906 * And if we need a pre-allocated page but don't yet have
907 * one, return a negative error to let the preallocation
908 * code know so that it can do so outside the page table
909 * lock.
910 */
911static inline int
912copy_present_page(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
913 pte_t *dst_pte, pte_t *src_pte, unsigned long addr, int *rss,
914 struct folio **prealloc, struct page *page)
915{
916 struct folio *new_folio;
917 pte_t pte;
918
919 new_folio = *prealloc;
920 if (!new_folio)
921 return -EAGAIN;
922
923 /*
924 * We have a prealloc page, all good! Take it
925 * over and copy the page & arm it.
926 */
927
928 if (copy_mc_user_highpage(&new_folio->page, page, addr, src_vma))
929 return -EHWPOISON;
930
931 *prealloc = NULL;
932 __folio_mark_uptodate(new_folio);
933 folio_add_new_anon_rmap(new_folio, dst_vma, addr, RMAP_EXCLUSIVE);
934 folio_add_lru_vma(new_folio, dst_vma);
935 rss[MM_ANONPAGES]++;
936
937 /* All done, just insert the new page copy in the child */
938 pte = mk_pte(&new_folio->page, dst_vma->vm_page_prot);
939 pte = maybe_mkwrite(pte_mkdirty(pte), dst_vma);
940 if (userfaultfd_pte_wp(dst_vma, ptep_get(src_pte)))
941 /* Uffd-wp needs to be delivered to dest pte as well */
942 pte = pte_mkuffd_wp(pte);
943 set_pte_at(dst_vma->vm_mm, addr, dst_pte, pte);
944 return 0;
945}
946
947static __always_inline void __copy_present_ptes(struct vm_area_struct *dst_vma,
948 struct vm_area_struct *src_vma, pte_t *dst_pte, pte_t *src_pte,
949 pte_t pte, unsigned long addr, int nr)
950{
951 struct mm_struct *src_mm = src_vma->vm_mm;
952
953 /* If it's a COW mapping, write protect it both processes. */
954 if (is_cow_mapping(src_vma->vm_flags) && pte_write(pte)) {
955 wrprotect_ptes(src_mm, addr, src_pte, nr);
956 pte = pte_wrprotect(pte);
957 }
958
959 /* If it's a shared mapping, mark it clean in the child. */
960 if (src_vma->vm_flags & VM_SHARED)
961 pte = pte_mkclean(pte);
962 pte = pte_mkold(pte);
963
964 if (!userfaultfd_wp(dst_vma))
965 pte = pte_clear_uffd_wp(pte);
966
967 set_ptes(dst_vma->vm_mm, addr, dst_pte, pte, nr);
968}
969
970/*
971 * Copy one present PTE, trying to batch-process subsequent PTEs that map
972 * consecutive pages of the same folio by copying them as well.
973 *
974 * Returns -EAGAIN if one preallocated page is required to copy the next PTE.
975 * Otherwise, returns the number of copied PTEs (at least 1).
976 */
977static inline int
978copy_present_ptes(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
979 pte_t *dst_pte, pte_t *src_pte, pte_t pte, unsigned long addr,
980 int max_nr, int *rss, struct folio **prealloc)
981{
982 struct page *page;
983 struct folio *folio;
984 bool any_writable;
985 fpb_t flags = 0;
986 int err, nr;
987
988 page = vm_normal_page(src_vma, addr, pte);
989 if (unlikely(!page))
990 goto copy_pte;
991
992 folio = page_folio(page);
993
994 /*
995 * If we likely have to copy, just don't bother with batching. Make
996 * sure that the common "small folio" case is as fast as possible
997 * by keeping the batching logic separate.
998 */
999 if (unlikely(!*prealloc && folio_test_large(folio) && max_nr != 1)) {
1000 if (src_vma->vm_flags & VM_SHARED)
1001 flags |= FPB_IGNORE_DIRTY;
1002 if (!vma_soft_dirty_enabled(src_vma))
1003 flags |= FPB_IGNORE_SOFT_DIRTY;
1004
1005 nr = folio_pte_batch(folio, addr, src_pte, pte, max_nr, flags,
1006 &any_writable, NULL, NULL);
1007 folio_ref_add(folio, nr);
1008 if (folio_test_anon(folio)) {
1009 if (unlikely(folio_try_dup_anon_rmap_ptes(folio, page,
1010 nr, src_vma))) {
1011 folio_ref_sub(folio, nr);
1012 return -EAGAIN;
1013 }
1014 rss[MM_ANONPAGES] += nr;
1015 VM_WARN_ON_FOLIO(PageAnonExclusive(page), folio);
1016 } else {
1017 folio_dup_file_rmap_ptes(folio, page, nr);
1018 rss[mm_counter_file(folio)] += nr;
1019 }
1020 if (any_writable)
1021 pte = pte_mkwrite(pte, src_vma);
1022 __copy_present_ptes(dst_vma, src_vma, dst_pte, src_pte, pte,
1023 addr, nr);
1024 return nr;
1025 }
1026
1027 folio_get(folio);
1028 if (folio_test_anon(folio)) {
1029 /*
1030 * If this page may have been pinned by the parent process,
1031 * copy the page immediately for the child so that we'll always
1032 * guarantee the pinned page won't be randomly replaced in the
1033 * future.
1034 */
1035 if (unlikely(folio_try_dup_anon_rmap_pte(folio, page, src_vma))) {
1036 /* Page may be pinned, we have to copy. */
1037 folio_put(folio);
1038 err = copy_present_page(dst_vma, src_vma, dst_pte, src_pte,
1039 addr, rss, prealloc, page);
1040 return err ? err : 1;
1041 }
1042 rss[MM_ANONPAGES]++;
1043 VM_WARN_ON_FOLIO(PageAnonExclusive(page), folio);
1044 } else {
1045 folio_dup_file_rmap_pte(folio, page);
1046 rss[mm_counter_file(folio)]++;
1047 }
1048
1049copy_pte:
1050 __copy_present_ptes(dst_vma, src_vma, dst_pte, src_pte, pte, addr, 1);
1051 return 1;
1052}
1053
1054static inline struct folio *folio_prealloc(struct mm_struct *src_mm,
1055 struct vm_area_struct *vma, unsigned long addr, bool need_zero)
1056{
1057 struct folio *new_folio;
1058
1059 if (need_zero)
1060 new_folio = vma_alloc_zeroed_movable_folio(vma, addr);
1061 else
1062 new_folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, addr);
1063
1064 if (!new_folio)
1065 return NULL;
1066
1067 if (mem_cgroup_charge(new_folio, src_mm, GFP_KERNEL)) {
1068 folio_put(new_folio);
1069 return NULL;
1070 }
1071 folio_throttle_swaprate(new_folio, GFP_KERNEL);
1072
1073 return new_folio;
1074}
1075
1076static int
1077copy_pte_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1078 pmd_t *dst_pmd, pmd_t *src_pmd, unsigned long addr,
1079 unsigned long end)
1080{
1081 struct mm_struct *dst_mm = dst_vma->vm_mm;
1082 struct mm_struct *src_mm = src_vma->vm_mm;
1083 pte_t *orig_src_pte, *orig_dst_pte;
1084 pte_t *src_pte, *dst_pte;
1085 pmd_t dummy_pmdval;
1086 pte_t ptent;
1087 spinlock_t *src_ptl, *dst_ptl;
1088 int progress, max_nr, ret = 0;
1089 int rss[NR_MM_COUNTERS];
1090 swp_entry_t entry = (swp_entry_t){0};
1091 struct folio *prealloc = NULL;
1092 int nr;
1093
1094again:
1095 progress = 0;
1096 init_rss_vec(rss);
1097
1098 /*
1099 * copy_pmd_range()'s prior pmd_none_or_clear_bad(src_pmd), and the
1100 * error handling here, assume that exclusive mmap_lock on dst and src
1101 * protects anon from unexpected THP transitions; with shmem and file
1102 * protected by mmap_lock-less collapse skipping areas with anon_vma
1103 * (whereas vma_needs_copy() skips areas without anon_vma). A rework
1104 * can remove such assumptions later, but this is good enough for now.
1105 */
1106 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
1107 if (!dst_pte) {
1108 ret = -ENOMEM;
1109 goto out;
1110 }
1111
1112 /*
1113 * We already hold the exclusive mmap_lock, the copy_pte_range() and
1114 * retract_page_tables() are using vma->anon_vma to be exclusive, so
1115 * the PTE page is stable, and there is no need to get pmdval and do
1116 * pmd_same() check.
1117 */
1118 src_pte = pte_offset_map_rw_nolock(src_mm, src_pmd, addr, &dummy_pmdval,
1119 &src_ptl);
1120 if (!src_pte) {
1121 pte_unmap_unlock(dst_pte, dst_ptl);
1122 /* ret == 0 */
1123 goto out;
1124 }
1125 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
1126 orig_src_pte = src_pte;
1127 orig_dst_pte = dst_pte;
1128 arch_enter_lazy_mmu_mode();
1129
1130 do {
1131 nr = 1;
1132
1133 /*
1134 * We are holding two locks at this point - either of them
1135 * could generate latencies in another task on another CPU.
1136 */
1137 if (progress >= 32) {
1138 progress = 0;
1139 if (need_resched() ||
1140 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
1141 break;
1142 }
1143 ptent = ptep_get(src_pte);
1144 if (pte_none(ptent)) {
1145 progress++;
1146 continue;
1147 }
1148 if (unlikely(!pte_present(ptent))) {
1149 ret = copy_nonpresent_pte(dst_mm, src_mm,
1150 dst_pte, src_pte,
1151 dst_vma, src_vma,
1152 addr, rss);
1153 if (ret == -EIO) {
1154 entry = pte_to_swp_entry(ptep_get(src_pte));
1155 break;
1156 } else if (ret == -EBUSY) {
1157 break;
1158 } else if (!ret) {
1159 progress += 8;
1160 continue;
1161 }
1162 ptent = ptep_get(src_pte);
1163 VM_WARN_ON_ONCE(!pte_present(ptent));
1164
1165 /*
1166 * Device exclusive entry restored, continue by copying
1167 * the now present pte.
1168 */
1169 WARN_ON_ONCE(ret != -ENOENT);
1170 }
1171 /* copy_present_ptes() will clear `*prealloc' if consumed */
1172 max_nr = (end - addr) / PAGE_SIZE;
1173 ret = copy_present_ptes(dst_vma, src_vma, dst_pte, src_pte,
1174 ptent, addr, max_nr, rss, &prealloc);
1175 /*
1176 * If we need a pre-allocated page for this pte, drop the
1177 * locks, allocate, and try again.
1178 * If copy failed due to hwpoison in source page, break out.
1179 */
1180 if (unlikely(ret == -EAGAIN || ret == -EHWPOISON))
1181 break;
1182 if (unlikely(prealloc)) {
1183 /*
1184 * pre-alloc page cannot be reused by next time so as
1185 * to strictly follow mempolicy (e.g., alloc_page_vma()
1186 * will allocate page according to address). This
1187 * could only happen if one pinned pte changed.
1188 */
1189 folio_put(prealloc);
1190 prealloc = NULL;
1191 }
1192 nr = ret;
1193 progress += 8 * nr;
1194 } while (dst_pte += nr, src_pte += nr, addr += PAGE_SIZE * nr,
1195 addr != end);
1196
1197 arch_leave_lazy_mmu_mode();
1198 pte_unmap_unlock(orig_src_pte, src_ptl);
1199 add_mm_rss_vec(dst_mm, rss);
1200 pte_unmap_unlock(orig_dst_pte, dst_ptl);
1201 cond_resched();
1202
1203 if (ret == -EIO) {
1204 VM_WARN_ON_ONCE(!entry.val);
1205 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0) {
1206 ret = -ENOMEM;
1207 goto out;
1208 }
1209 entry.val = 0;
1210 } else if (ret == -EBUSY || unlikely(ret == -EHWPOISON)) {
1211 goto out;
1212 } else if (ret == -EAGAIN) {
1213 prealloc = folio_prealloc(src_mm, src_vma, addr, false);
1214 if (!prealloc)
1215 return -ENOMEM;
1216 } else if (ret < 0) {
1217 VM_WARN_ON_ONCE(1);
1218 }
1219
1220 /* We've captured and resolved the error. Reset, try again. */
1221 ret = 0;
1222
1223 if (addr != end)
1224 goto again;
1225out:
1226 if (unlikely(prealloc))
1227 folio_put(prealloc);
1228 return ret;
1229}
1230
1231static inline int
1232copy_pmd_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1233 pud_t *dst_pud, pud_t *src_pud, unsigned long addr,
1234 unsigned long end)
1235{
1236 struct mm_struct *dst_mm = dst_vma->vm_mm;
1237 struct mm_struct *src_mm = src_vma->vm_mm;
1238 pmd_t *src_pmd, *dst_pmd;
1239 unsigned long next;
1240
1241 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
1242 if (!dst_pmd)
1243 return -ENOMEM;
1244 src_pmd = pmd_offset(src_pud, addr);
1245 do {
1246 next = pmd_addr_end(addr, end);
1247 if (is_swap_pmd(*src_pmd) || pmd_trans_huge(*src_pmd)
1248 || pmd_devmap(*src_pmd)) {
1249 int err;
1250 VM_BUG_ON_VMA(next-addr != HPAGE_PMD_SIZE, src_vma);
1251 err = copy_huge_pmd(dst_mm, src_mm, dst_pmd, src_pmd,
1252 addr, dst_vma, src_vma);
1253 if (err == -ENOMEM)
1254 return -ENOMEM;
1255 if (!err)
1256 continue;
1257 /* fall through */
1258 }
1259 if (pmd_none_or_clear_bad(src_pmd))
1260 continue;
1261 if (copy_pte_range(dst_vma, src_vma, dst_pmd, src_pmd,
1262 addr, next))
1263 return -ENOMEM;
1264 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
1265 return 0;
1266}
1267
1268static inline int
1269copy_pud_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1270 p4d_t *dst_p4d, p4d_t *src_p4d, unsigned long addr,
1271 unsigned long end)
1272{
1273 struct mm_struct *dst_mm = dst_vma->vm_mm;
1274 struct mm_struct *src_mm = src_vma->vm_mm;
1275 pud_t *src_pud, *dst_pud;
1276 unsigned long next;
1277
1278 dst_pud = pud_alloc(dst_mm, dst_p4d, addr);
1279 if (!dst_pud)
1280 return -ENOMEM;
1281 src_pud = pud_offset(src_p4d, addr);
1282 do {
1283 next = pud_addr_end(addr, end);
1284 if (pud_trans_huge(*src_pud) || pud_devmap(*src_pud)) {
1285 int err;
1286
1287 VM_BUG_ON_VMA(next-addr != HPAGE_PUD_SIZE, src_vma);
1288 err = copy_huge_pud(dst_mm, src_mm,
1289 dst_pud, src_pud, addr, src_vma);
1290 if (err == -ENOMEM)
1291 return -ENOMEM;
1292 if (!err)
1293 continue;
1294 /* fall through */
1295 }
1296 if (pud_none_or_clear_bad(src_pud))
1297 continue;
1298 if (copy_pmd_range(dst_vma, src_vma, dst_pud, src_pud,
1299 addr, next))
1300 return -ENOMEM;
1301 } while (dst_pud++, src_pud++, addr = next, addr != end);
1302 return 0;
1303}
1304
1305static inline int
1306copy_p4d_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma,
1307 pgd_t *dst_pgd, pgd_t *src_pgd, unsigned long addr,
1308 unsigned long end)
1309{
1310 struct mm_struct *dst_mm = dst_vma->vm_mm;
1311 p4d_t *src_p4d, *dst_p4d;
1312 unsigned long next;
1313
1314 dst_p4d = p4d_alloc(dst_mm, dst_pgd, addr);
1315 if (!dst_p4d)
1316 return -ENOMEM;
1317 src_p4d = p4d_offset(src_pgd, addr);
1318 do {
1319 next = p4d_addr_end(addr, end);
1320 if (p4d_none_or_clear_bad(src_p4d))
1321 continue;
1322 if (copy_pud_range(dst_vma, src_vma, dst_p4d, src_p4d,
1323 addr, next))
1324 return -ENOMEM;
1325 } while (dst_p4d++, src_p4d++, addr = next, addr != end);
1326 return 0;
1327}
1328
1329/*
1330 * Return true if the vma needs to copy the pgtable during this fork(). Return
1331 * false when we can speed up fork() by allowing lazy page faults later until
1332 * when the child accesses the memory range.
1333 */
1334static bool
1335vma_needs_copy(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
1336{
1337 /*
1338 * Always copy pgtables when dst_vma has uffd-wp enabled even if it's
1339 * file-backed (e.g. shmem). Because when uffd-wp is enabled, pgtable
1340 * contains uffd-wp protection information, that's something we can't
1341 * retrieve from page cache, and skip copying will lose those info.
1342 */
1343 if (userfaultfd_wp(dst_vma))
1344 return true;
1345
1346 if (src_vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
1347 return true;
1348
1349 if (src_vma->anon_vma)
1350 return true;
1351
1352 /*
1353 * Don't copy ptes where a page fault will fill them correctly. Fork
1354 * becomes much lighter when there are big shared or private readonly
1355 * mappings. The tradeoff is that copy_page_range is more efficient
1356 * than faulting.
1357 */
1358 return false;
1359}
1360
1361int
1362copy_page_range(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma)
1363{
1364 pgd_t *src_pgd, *dst_pgd;
1365 unsigned long next;
1366 unsigned long addr = src_vma->vm_start;
1367 unsigned long end = src_vma->vm_end;
1368 struct mm_struct *dst_mm = dst_vma->vm_mm;
1369 struct mm_struct *src_mm = src_vma->vm_mm;
1370 struct mmu_notifier_range range;
1371 bool is_cow;
1372 int ret;
1373
1374 if (!vma_needs_copy(dst_vma, src_vma))
1375 return 0;
1376
1377 if (is_vm_hugetlb_page(src_vma))
1378 return copy_hugetlb_page_range(dst_mm, src_mm, dst_vma, src_vma);
1379
1380 if (unlikely(src_vma->vm_flags & VM_PFNMAP)) {
1381 /*
1382 * We do not free on error cases below as remove_vma
1383 * gets called on error from higher level routine
1384 */
1385 ret = track_pfn_copy(src_vma);
1386 if (ret)
1387 return ret;
1388 }
1389
1390 /*
1391 * We need to invalidate the secondary MMU mappings only when
1392 * there could be a permission downgrade on the ptes of the
1393 * parent mm. And a permission downgrade will only happen if
1394 * is_cow_mapping() returns true.
1395 */
1396 is_cow = is_cow_mapping(src_vma->vm_flags);
1397
1398 if (is_cow) {
1399 mmu_notifier_range_init(&range, MMU_NOTIFY_PROTECTION_PAGE,
1400 0, src_mm, addr, end);
1401 mmu_notifier_invalidate_range_start(&range);
1402 /*
1403 * Disabling preemption is not needed for the write side, as
1404 * the read side doesn't spin, but goes to the mmap_lock.
1405 *
1406 * Use the raw variant of the seqcount_t write API to avoid
1407 * lockdep complaining about preemptibility.
1408 */
1409 vma_assert_write_locked(src_vma);
1410 raw_write_seqcount_begin(&src_mm->write_protect_seq);
1411 }
1412
1413 ret = 0;
1414 dst_pgd = pgd_offset(dst_mm, addr);
1415 src_pgd = pgd_offset(src_mm, addr);
1416 do {
1417 next = pgd_addr_end(addr, end);
1418 if (pgd_none_or_clear_bad(src_pgd))
1419 continue;
1420 if (unlikely(copy_p4d_range(dst_vma, src_vma, dst_pgd, src_pgd,
1421 addr, next))) {
1422 untrack_pfn_clear(dst_vma);
1423 ret = -ENOMEM;
1424 break;
1425 }
1426 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1427
1428 if (is_cow) {
1429 raw_write_seqcount_end(&src_mm->write_protect_seq);
1430 mmu_notifier_invalidate_range_end(&range);
1431 }
1432 return ret;
1433}
1434
1435/* Whether we should zap all COWed (private) pages too */
1436static inline bool should_zap_cows(struct zap_details *details)
1437{
1438 /* By default, zap all pages */
1439 if (!details)
1440 return true;
1441
1442 /* Or, we zap COWed pages only if the caller wants to */
1443 return details->even_cows;
1444}
1445
1446/* Decides whether we should zap this folio with the folio pointer specified */
1447static inline bool should_zap_folio(struct zap_details *details,
1448 struct folio *folio)
1449{
1450 /* If we can make a decision without *folio.. */
1451 if (should_zap_cows(details))
1452 return true;
1453
1454 /* Otherwise we should only zap non-anon folios */
1455 return !folio_test_anon(folio);
1456}
1457
1458static inline bool zap_drop_markers(struct zap_details *details)
1459{
1460 if (!details)
1461 return false;
1462
1463 return details->zap_flags & ZAP_FLAG_DROP_MARKER;
1464}
1465
1466/*
1467 * This function makes sure that we'll replace the none pte with an uffd-wp
1468 * swap special pte marker when necessary. Must be with the pgtable lock held.
1469 */
1470static inline void
1471zap_install_uffd_wp_if_needed(struct vm_area_struct *vma,
1472 unsigned long addr, pte_t *pte, int nr,
1473 struct zap_details *details, pte_t pteval)
1474{
1475 /* Zap on anonymous always means dropping everything */
1476 if (vma_is_anonymous(vma))
1477 return;
1478
1479 if (zap_drop_markers(details))
1480 return;
1481
1482 for (;;) {
1483 /* the PFN in the PTE is irrelevant. */
1484 pte_install_uffd_wp_if_needed(vma, addr, pte, pteval);
1485 if (--nr == 0)
1486 break;
1487 pte++;
1488 addr += PAGE_SIZE;
1489 }
1490}
1491
1492static __always_inline void zap_present_folio_ptes(struct mmu_gather *tlb,
1493 struct vm_area_struct *vma, struct folio *folio,
1494 struct page *page, pte_t *pte, pte_t ptent, unsigned int nr,
1495 unsigned long addr, struct zap_details *details, int *rss,
1496 bool *force_flush, bool *force_break)
1497{
1498 struct mm_struct *mm = tlb->mm;
1499 bool delay_rmap = false;
1500
1501 if (!folio_test_anon(folio)) {
1502 ptent = get_and_clear_full_ptes(mm, addr, pte, nr, tlb->fullmm);
1503 if (pte_dirty(ptent)) {
1504 folio_mark_dirty(folio);
1505 if (tlb_delay_rmap(tlb)) {
1506 delay_rmap = true;
1507 *force_flush = true;
1508 }
1509 }
1510 if (pte_young(ptent) && likely(vma_has_recency(vma)))
1511 folio_mark_accessed(folio);
1512 rss[mm_counter(folio)] -= nr;
1513 } else {
1514 /* We don't need up-to-date accessed/dirty bits. */
1515 clear_full_ptes(mm, addr, pte, nr, tlb->fullmm);
1516 rss[MM_ANONPAGES] -= nr;
1517 }
1518 /* Checking a single PTE in a batch is sufficient. */
1519 arch_check_zapped_pte(vma, ptent);
1520 tlb_remove_tlb_entries(tlb, pte, nr, addr);
1521 if (unlikely(userfaultfd_pte_wp(vma, ptent)))
1522 zap_install_uffd_wp_if_needed(vma, addr, pte, nr, details,
1523 ptent);
1524
1525 if (!delay_rmap) {
1526 folio_remove_rmap_ptes(folio, page, nr, vma);
1527
1528 if (unlikely(folio_mapcount(folio) < 0))
1529 print_bad_pte(vma, addr, ptent, page);
1530 }
1531 if (unlikely(__tlb_remove_folio_pages(tlb, page, nr, delay_rmap))) {
1532 *force_flush = true;
1533 *force_break = true;
1534 }
1535}
1536
1537/*
1538 * Zap or skip at least one present PTE, trying to batch-process subsequent
1539 * PTEs that map consecutive pages of the same folio.
1540 *
1541 * Returns the number of processed (skipped or zapped) PTEs (at least 1).
1542 */
1543static inline int zap_present_ptes(struct mmu_gather *tlb,
1544 struct vm_area_struct *vma, pte_t *pte, pte_t ptent,
1545 unsigned int max_nr, unsigned long addr,
1546 struct zap_details *details, int *rss, bool *force_flush,
1547 bool *force_break)
1548{
1549 const fpb_t fpb_flags = FPB_IGNORE_DIRTY | FPB_IGNORE_SOFT_DIRTY;
1550 struct mm_struct *mm = tlb->mm;
1551 struct folio *folio;
1552 struct page *page;
1553 int nr;
1554
1555 page = vm_normal_page(vma, addr, ptent);
1556 if (!page) {
1557 /* We don't need up-to-date accessed/dirty bits. */
1558 ptep_get_and_clear_full(mm, addr, pte, tlb->fullmm);
1559 arch_check_zapped_pte(vma, ptent);
1560 tlb_remove_tlb_entry(tlb, pte, addr);
1561 if (userfaultfd_pte_wp(vma, ptent))
1562 zap_install_uffd_wp_if_needed(vma, addr, pte, 1,
1563 details, ptent);
1564 ksm_might_unmap_zero_page(mm, ptent);
1565 return 1;
1566 }
1567
1568 folio = page_folio(page);
1569 if (unlikely(!should_zap_folio(details, folio)))
1570 return 1;
1571
1572 /*
1573 * Make sure that the common "small folio" case is as fast as possible
1574 * by keeping the batching logic separate.
1575 */
1576 if (unlikely(folio_test_large(folio) && max_nr != 1)) {
1577 nr = folio_pte_batch(folio, addr, pte, ptent, max_nr, fpb_flags,
1578 NULL, NULL, NULL);
1579
1580 zap_present_folio_ptes(tlb, vma, folio, page, pte, ptent, nr,
1581 addr, details, rss, force_flush,
1582 force_break);
1583 return nr;
1584 }
1585 zap_present_folio_ptes(tlb, vma, folio, page, pte, ptent, 1, addr,
1586 details, rss, force_flush, force_break);
1587 return 1;
1588}
1589
1590static unsigned long zap_pte_range(struct mmu_gather *tlb,
1591 struct vm_area_struct *vma, pmd_t *pmd,
1592 unsigned long addr, unsigned long end,
1593 struct zap_details *details)
1594{
1595 bool force_flush = false, force_break = false;
1596 struct mm_struct *mm = tlb->mm;
1597 int rss[NR_MM_COUNTERS];
1598 spinlock_t *ptl;
1599 pte_t *start_pte;
1600 pte_t *pte;
1601 swp_entry_t entry;
1602 int nr;
1603
1604 tlb_change_page_size(tlb, PAGE_SIZE);
1605 init_rss_vec(rss);
1606 start_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1607 if (!pte)
1608 return addr;
1609
1610 flush_tlb_batched_pending(mm);
1611 arch_enter_lazy_mmu_mode();
1612 do {
1613 pte_t ptent = ptep_get(pte);
1614 struct folio *folio;
1615 struct page *page;
1616 int max_nr;
1617
1618 nr = 1;
1619 if (pte_none(ptent))
1620 continue;
1621
1622 if (need_resched())
1623 break;
1624
1625 if (pte_present(ptent)) {
1626 max_nr = (end - addr) / PAGE_SIZE;
1627 nr = zap_present_ptes(tlb, vma, pte, ptent, max_nr,
1628 addr, details, rss, &force_flush,
1629 &force_break);
1630 if (unlikely(force_break)) {
1631 addr += nr * PAGE_SIZE;
1632 break;
1633 }
1634 continue;
1635 }
1636
1637 entry = pte_to_swp_entry(ptent);
1638 if (is_device_private_entry(entry) ||
1639 is_device_exclusive_entry(entry)) {
1640 page = pfn_swap_entry_to_page(entry);
1641 folio = page_folio(page);
1642 if (unlikely(!should_zap_folio(details, folio)))
1643 continue;
1644 /*
1645 * Both device private/exclusive mappings should only
1646 * work with anonymous page so far, so we don't need to
1647 * consider uffd-wp bit when zap. For more information,
1648 * see zap_install_uffd_wp_if_needed().
1649 */
1650 WARN_ON_ONCE(!vma_is_anonymous(vma));
1651 rss[mm_counter(folio)]--;
1652 if (is_device_private_entry(entry))
1653 folio_remove_rmap_pte(folio, page, vma);
1654 folio_put(folio);
1655 } else if (!non_swap_entry(entry)) {
1656 max_nr = (end - addr) / PAGE_SIZE;
1657 nr = swap_pte_batch(pte, max_nr, ptent);
1658 /* Genuine swap entries, hence a private anon pages */
1659 if (!should_zap_cows(details))
1660 continue;
1661 rss[MM_SWAPENTS] -= nr;
1662 free_swap_and_cache_nr(entry, nr);
1663 } else if (is_migration_entry(entry)) {
1664 folio = pfn_swap_entry_folio(entry);
1665 if (!should_zap_folio(details, folio))
1666 continue;
1667 rss[mm_counter(folio)]--;
1668 } else if (pte_marker_entry_uffd_wp(entry)) {
1669 /*
1670 * For anon: always drop the marker; for file: only
1671 * drop the marker if explicitly requested.
1672 */
1673 if (!vma_is_anonymous(vma) &&
1674 !zap_drop_markers(details))
1675 continue;
1676 } else if (is_guard_swp_entry(entry)) {
1677 /*
1678 * Ordinary zapping should not remove guard PTE
1679 * markers. Only do so if we should remove PTE markers
1680 * in general.
1681 */
1682 if (!zap_drop_markers(details))
1683 continue;
1684 } else if (is_hwpoison_entry(entry) ||
1685 is_poisoned_swp_entry(entry)) {
1686 if (!should_zap_cows(details))
1687 continue;
1688 } else {
1689 /* We should have covered all the swap entry types */
1690 pr_alert("unrecognized swap entry 0x%lx\n", entry.val);
1691 WARN_ON_ONCE(1);
1692 }
1693 clear_not_present_full_ptes(mm, addr, pte, nr, tlb->fullmm);
1694 zap_install_uffd_wp_if_needed(vma, addr, pte, nr, details, ptent);
1695 } while (pte += nr, addr += PAGE_SIZE * nr, addr != end);
1696
1697 add_mm_rss_vec(mm, rss);
1698 arch_leave_lazy_mmu_mode();
1699
1700 /* Do the actual TLB flush before dropping ptl */
1701 if (force_flush) {
1702 tlb_flush_mmu_tlbonly(tlb);
1703 tlb_flush_rmaps(tlb, vma);
1704 }
1705 pte_unmap_unlock(start_pte, ptl);
1706
1707 /*
1708 * If we forced a TLB flush (either due to running out of
1709 * batch buffers or because we needed to flush dirty TLB
1710 * entries before releasing the ptl), free the batched
1711 * memory too. Come back again if we didn't do everything.
1712 */
1713 if (force_flush)
1714 tlb_flush_mmu(tlb);
1715
1716 return addr;
1717}
1718
1719static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1720 struct vm_area_struct *vma, pud_t *pud,
1721 unsigned long addr, unsigned long end,
1722 struct zap_details *details)
1723{
1724 pmd_t *pmd;
1725 unsigned long next;
1726
1727 pmd = pmd_offset(pud, addr);
1728 do {
1729 next = pmd_addr_end(addr, end);
1730 if (is_swap_pmd(*pmd) || pmd_trans_huge(*pmd) || pmd_devmap(*pmd)) {
1731 if (next - addr != HPAGE_PMD_SIZE)
1732 __split_huge_pmd(vma, pmd, addr, false, NULL);
1733 else if (zap_huge_pmd(tlb, vma, pmd, addr)) {
1734 addr = next;
1735 continue;
1736 }
1737 /* fall through */
1738 } else if (details && details->single_folio &&
1739 folio_test_pmd_mappable(details->single_folio) &&
1740 next - addr == HPAGE_PMD_SIZE && pmd_none(*pmd)) {
1741 spinlock_t *ptl = pmd_lock(tlb->mm, pmd);
1742 /*
1743 * Take and drop THP pmd lock so that we cannot return
1744 * prematurely, while zap_huge_pmd() has cleared *pmd,
1745 * but not yet decremented compound_mapcount().
1746 */
1747 spin_unlock(ptl);
1748 }
1749 if (pmd_none(*pmd)) {
1750 addr = next;
1751 continue;
1752 }
1753 addr = zap_pte_range(tlb, vma, pmd, addr, next, details);
1754 if (addr != next)
1755 pmd--;
1756 } while (pmd++, cond_resched(), addr != end);
1757
1758 return addr;
1759}
1760
1761static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1762 struct vm_area_struct *vma, p4d_t *p4d,
1763 unsigned long addr, unsigned long end,
1764 struct zap_details *details)
1765{
1766 pud_t *pud;
1767 unsigned long next;
1768
1769 pud = pud_offset(p4d, addr);
1770 do {
1771 next = pud_addr_end(addr, end);
1772 if (pud_trans_huge(*pud) || pud_devmap(*pud)) {
1773 if (next - addr != HPAGE_PUD_SIZE) {
1774 mmap_assert_locked(tlb->mm);
1775 split_huge_pud(vma, pud, addr);
1776 } else if (zap_huge_pud(tlb, vma, pud, addr))
1777 goto next;
1778 /* fall through */
1779 }
1780 if (pud_none_or_clear_bad(pud))
1781 continue;
1782 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1783next:
1784 cond_resched();
1785 } while (pud++, addr = next, addr != end);
1786
1787 return addr;
1788}
1789
1790static inline unsigned long zap_p4d_range(struct mmu_gather *tlb,
1791 struct vm_area_struct *vma, pgd_t *pgd,
1792 unsigned long addr, unsigned long end,
1793 struct zap_details *details)
1794{
1795 p4d_t *p4d;
1796 unsigned long next;
1797
1798 p4d = p4d_offset(pgd, addr);
1799 do {
1800 next = p4d_addr_end(addr, end);
1801 if (p4d_none_or_clear_bad(p4d))
1802 continue;
1803 next = zap_pud_range(tlb, vma, p4d, addr, next, details);
1804 } while (p4d++, addr = next, addr != end);
1805
1806 return addr;
1807}
1808
1809void unmap_page_range(struct mmu_gather *tlb,
1810 struct vm_area_struct *vma,
1811 unsigned long addr, unsigned long end,
1812 struct zap_details *details)
1813{
1814 pgd_t *pgd;
1815 unsigned long next;
1816
1817 BUG_ON(addr >= end);
1818 tlb_start_vma(tlb, vma);
1819 pgd = pgd_offset(vma->vm_mm, addr);
1820 do {
1821 next = pgd_addr_end(addr, end);
1822 if (pgd_none_or_clear_bad(pgd))
1823 continue;
1824 next = zap_p4d_range(tlb, vma, pgd, addr, next, details);
1825 } while (pgd++, addr = next, addr != end);
1826 tlb_end_vma(tlb, vma);
1827}
1828
1829
1830static void unmap_single_vma(struct mmu_gather *tlb,
1831 struct vm_area_struct *vma, unsigned long start_addr,
1832 unsigned long end_addr,
1833 struct zap_details *details, bool mm_wr_locked)
1834{
1835 unsigned long start = max(vma->vm_start, start_addr);
1836 unsigned long end;
1837
1838 if (start >= vma->vm_end)
1839 return;
1840 end = min(vma->vm_end, end_addr);
1841 if (end <= vma->vm_start)
1842 return;
1843
1844 if (vma->vm_file)
1845 uprobe_munmap(vma, start, end);
1846
1847 if (unlikely(vma->vm_flags & VM_PFNMAP))
1848 untrack_pfn(vma, 0, 0, mm_wr_locked);
1849
1850 if (start != end) {
1851 if (unlikely(is_vm_hugetlb_page(vma))) {
1852 /*
1853 * It is undesirable to test vma->vm_file as it
1854 * should be non-null for valid hugetlb area.
1855 * However, vm_file will be NULL in the error
1856 * cleanup path of mmap_region. When
1857 * hugetlbfs ->mmap method fails,
1858 * mmap_region() nullifies vma->vm_file
1859 * before calling this function to clean up.
1860 * Since no pte has actually been setup, it is
1861 * safe to do nothing in this case.
1862 */
1863 if (vma->vm_file) {
1864 zap_flags_t zap_flags = details ?
1865 details->zap_flags : 0;
1866 __unmap_hugepage_range(tlb, vma, start, end,
1867 NULL, zap_flags);
1868 }
1869 } else
1870 unmap_page_range(tlb, vma, start, end, details);
1871 }
1872}
1873
1874/**
1875 * unmap_vmas - unmap a range of memory covered by a list of vma's
1876 * @tlb: address of the caller's struct mmu_gather
1877 * @mas: the maple state
1878 * @vma: the starting vma
1879 * @start_addr: virtual address at which to start unmapping
1880 * @end_addr: virtual address at which to end unmapping
1881 * @tree_end: The maximum index to check
1882 * @mm_wr_locked: lock flag
1883 *
1884 * Unmap all pages in the vma list.
1885 *
1886 * Only addresses between `start' and `end' will be unmapped.
1887 *
1888 * The VMA list must be sorted in ascending virtual address order.
1889 *
1890 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1891 * range after unmap_vmas() returns. So the only responsibility here is to
1892 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1893 * drops the lock and schedules.
1894 */
1895void unmap_vmas(struct mmu_gather *tlb, struct ma_state *mas,
1896 struct vm_area_struct *vma, unsigned long start_addr,
1897 unsigned long end_addr, unsigned long tree_end,
1898 bool mm_wr_locked)
1899{
1900 struct mmu_notifier_range range;
1901 struct zap_details details = {
1902 .zap_flags = ZAP_FLAG_DROP_MARKER | ZAP_FLAG_UNMAP,
1903 /* Careful - we need to zap private pages too! */
1904 .even_cows = true,
1905 };
1906
1907 mmu_notifier_range_init(&range, MMU_NOTIFY_UNMAP, 0, vma->vm_mm,
1908 start_addr, end_addr);
1909 mmu_notifier_invalidate_range_start(&range);
1910 do {
1911 unsigned long start = start_addr;
1912 unsigned long end = end_addr;
1913 hugetlb_zap_begin(vma, &start, &end);
1914 unmap_single_vma(tlb, vma, start, end, &details,
1915 mm_wr_locked);
1916 hugetlb_zap_end(vma, &details);
1917 vma = mas_find(mas, tree_end - 1);
1918 } while (vma && likely(!xa_is_zero(vma)));
1919 mmu_notifier_invalidate_range_end(&range);
1920}
1921
1922/**
1923 * zap_page_range_single - remove user pages in a given range
1924 * @vma: vm_area_struct holding the applicable pages
1925 * @address: starting address of pages to zap
1926 * @size: number of bytes to zap
1927 * @details: details of shared cache invalidation
1928 *
1929 * The range must fit into one VMA.
1930 */
1931void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1932 unsigned long size, struct zap_details *details)
1933{
1934 const unsigned long end = address + size;
1935 struct mmu_notifier_range range;
1936 struct mmu_gather tlb;
1937
1938 lru_add_drain();
1939 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma->vm_mm,
1940 address, end);
1941 hugetlb_zap_begin(vma, &range.start, &range.end);
1942 tlb_gather_mmu(&tlb, vma->vm_mm);
1943 update_hiwater_rss(vma->vm_mm);
1944 mmu_notifier_invalidate_range_start(&range);
1945 /*
1946 * unmap 'address-end' not 'range.start-range.end' as range
1947 * could have been expanded for hugetlb pmd sharing.
1948 */
1949 unmap_single_vma(&tlb, vma, address, end, details, false);
1950 mmu_notifier_invalidate_range_end(&range);
1951 tlb_finish_mmu(&tlb);
1952 hugetlb_zap_end(vma, details);
1953}
1954
1955/**
1956 * zap_vma_ptes - remove ptes mapping the vma
1957 * @vma: vm_area_struct holding ptes to be zapped
1958 * @address: starting address of pages to zap
1959 * @size: number of bytes to zap
1960 *
1961 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1962 *
1963 * The entire address range must be fully contained within the vma.
1964 *
1965 */
1966void zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1967 unsigned long size)
1968{
1969 if (!range_in_vma(vma, address, address + size) ||
1970 !(vma->vm_flags & VM_PFNMAP))
1971 return;
1972
1973 zap_page_range_single(vma, address, size, NULL);
1974}
1975EXPORT_SYMBOL_GPL(zap_vma_ptes);
1976
1977static pmd_t *walk_to_pmd(struct mm_struct *mm, unsigned long addr)
1978{
1979 pgd_t *pgd;
1980 p4d_t *p4d;
1981 pud_t *pud;
1982 pmd_t *pmd;
1983
1984 pgd = pgd_offset(mm, addr);
1985 p4d = p4d_alloc(mm, pgd, addr);
1986 if (!p4d)
1987 return NULL;
1988 pud = pud_alloc(mm, p4d, addr);
1989 if (!pud)
1990 return NULL;
1991 pmd = pmd_alloc(mm, pud, addr);
1992 if (!pmd)
1993 return NULL;
1994
1995 VM_BUG_ON(pmd_trans_huge(*pmd));
1996 return pmd;
1997}
1998
1999pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
2000 spinlock_t **ptl)
2001{
2002 pmd_t *pmd = walk_to_pmd(mm, addr);
2003
2004 if (!pmd)
2005 return NULL;
2006 return pte_alloc_map_lock(mm, pmd, addr, ptl);
2007}
2008
2009static bool vm_mixed_zeropage_allowed(struct vm_area_struct *vma)
2010{
2011 VM_WARN_ON_ONCE(vma->vm_flags & VM_PFNMAP);
2012 /*
2013 * Whoever wants to forbid the zeropage after some zeropages
2014 * might already have been mapped has to scan the page tables and
2015 * bail out on any zeropages. Zeropages in COW mappings can
2016 * be unshared using FAULT_FLAG_UNSHARE faults.
2017 */
2018 if (mm_forbids_zeropage(vma->vm_mm))
2019 return false;
2020 /* zeropages in COW mappings are common and unproblematic. */
2021 if (is_cow_mapping(vma->vm_flags))
2022 return true;
2023 /* Mappings that do not allow for writable PTEs are unproblematic. */
2024 if (!(vma->vm_flags & (VM_WRITE | VM_MAYWRITE)))
2025 return true;
2026 /*
2027 * Why not allow any VMA that has vm_ops->pfn_mkwrite? GUP could
2028 * find the shared zeropage and longterm-pin it, which would
2029 * be problematic as soon as the zeropage gets replaced by a different
2030 * page due to vma->vm_ops->pfn_mkwrite, because what's mapped would
2031 * now differ to what GUP looked up. FSDAX is incompatible to
2032 * FOLL_LONGTERM and VM_IO is incompatible to GUP completely (see
2033 * check_vma_flags).
2034 */
2035 return vma->vm_ops && vma->vm_ops->pfn_mkwrite &&
2036 (vma_is_fsdax(vma) || vma->vm_flags & VM_IO);
2037}
2038
2039static int validate_page_before_insert(struct vm_area_struct *vma,
2040 struct page *page)
2041{
2042 struct folio *folio = page_folio(page);
2043
2044 if (!folio_ref_count(folio))
2045 return -EINVAL;
2046 if (unlikely(is_zero_folio(folio))) {
2047 if (!vm_mixed_zeropage_allowed(vma))
2048 return -EINVAL;
2049 return 0;
2050 }
2051 if (folio_test_anon(folio) || folio_test_slab(folio) ||
2052 page_has_type(page))
2053 return -EINVAL;
2054 flush_dcache_folio(folio);
2055 return 0;
2056}
2057
2058static int insert_page_into_pte_locked(struct vm_area_struct *vma, pte_t *pte,
2059 unsigned long addr, struct page *page, pgprot_t prot)
2060{
2061 struct folio *folio = page_folio(page);
2062 pte_t pteval;
2063
2064 if (!pte_none(ptep_get(pte)))
2065 return -EBUSY;
2066 /* Ok, finally just insert the thing.. */
2067 pteval = mk_pte(page, prot);
2068 if (unlikely(is_zero_folio(folio))) {
2069 pteval = pte_mkspecial(pteval);
2070 } else {
2071 folio_get(folio);
2072 inc_mm_counter(vma->vm_mm, mm_counter_file(folio));
2073 folio_add_file_rmap_pte(folio, page, vma);
2074 }
2075 set_pte_at(vma->vm_mm, addr, pte, pteval);
2076 return 0;
2077}
2078
2079static int insert_page(struct vm_area_struct *vma, unsigned long addr,
2080 struct page *page, pgprot_t prot)
2081{
2082 int retval;
2083 pte_t *pte;
2084 spinlock_t *ptl;
2085
2086 retval = validate_page_before_insert(vma, page);
2087 if (retval)
2088 goto out;
2089 retval = -ENOMEM;
2090 pte = get_locked_pte(vma->vm_mm, addr, &ptl);
2091 if (!pte)
2092 goto out;
2093 retval = insert_page_into_pte_locked(vma, pte, addr, page, prot);
2094 pte_unmap_unlock(pte, ptl);
2095out:
2096 return retval;
2097}
2098
2099static int insert_page_in_batch_locked(struct vm_area_struct *vma, pte_t *pte,
2100 unsigned long addr, struct page *page, pgprot_t prot)
2101{
2102 int err;
2103
2104 err = validate_page_before_insert(vma, page);
2105 if (err)
2106 return err;
2107 return insert_page_into_pte_locked(vma, pte, addr, page, prot);
2108}
2109
2110/* insert_pages() amortizes the cost of spinlock operations
2111 * when inserting pages in a loop.
2112 */
2113static int insert_pages(struct vm_area_struct *vma, unsigned long addr,
2114 struct page **pages, unsigned long *num, pgprot_t prot)
2115{
2116 pmd_t *pmd = NULL;
2117 pte_t *start_pte, *pte;
2118 spinlock_t *pte_lock;
2119 struct mm_struct *const mm = vma->vm_mm;
2120 unsigned long curr_page_idx = 0;
2121 unsigned long remaining_pages_total = *num;
2122 unsigned long pages_to_write_in_pmd;
2123 int ret;
2124more:
2125 ret = -EFAULT;
2126 pmd = walk_to_pmd(mm, addr);
2127 if (!pmd)
2128 goto out;
2129
2130 pages_to_write_in_pmd = min_t(unsigned long,
2131 remaining_pages_total, PTRS_PER_PTE - pte_index(addr));
2132
2133 /* Allocate the PTE if necessary; takes PMD lock once only. */
2134 ret = -ENOMEM;
2135 if (pte_alloc(mm, pmd))
2136 goto out;
2137
2138 while (pages_to_write_in_pmd) {
2139 int pte_idx = 0;
2140 const int batch_size = min_t(int, pages_to_write_in_pmd, 8);
2141
2142 start_pte = pte_offset_map_lock(mm, pmd, addr, &pte_lock);
2143 if (!start_pte) {
2144 ret = -EFAULT;
2145 goto out;
2146 }
2147 for (pte = start_pte; pte_idx < batch_size; ++pte, ++pte_idx) {
2148 int err = insert_page_in_batch_locked(vma, pte,
2149 addr, pages[curr_page_idx], prot);
2150 if (unlikely(err)) {
2151 pte_unmap_unlock(start_pte, pte_lock);
2152 ret = err;
2153 remaining_pages_total -= pte_idx;
2154 goto out;
2155 }
2156 addr += PAGE_SIZE;
2157 ++curr_page_idx;
2158 }
2159 pte_unmap_unlock(start_pte, pte_lock);
2160 pages_to_write_in_pmd -= batch_size;
2161 remaining_pages_total -= batch_size;
2162 }
2163 if (remaining_pages_total)
2164 goto more;
2165 ret = 0;
2166out:
2167 *num = remaining_pages_total;
2168 return ret;
2169}
2170
2171/**
2172 * vm_insert_pages - insert multiple pages into user vma, batching the pmd lock.
2173 * @vma: user vma to map to
2174 * @addr: target start user address of these pages
2175 * @pages: source kernel pages
2176 * @num: in: number of pages to map. out: number of pages that were *not*
2177 * mapped. (0 means all pages were successfully mapped).
2178 *
2179 * Preferred over vm_insert_page() when inserting multiple pages.
2180 *
2181 * In case of error, we may have mapped a subset of the provided
2182 * pages. It is the caller's responsibility to account for this case.
2183 *
2184 * The same restrictions apply as in vm_insert_page().
2185 */
2186int vm_insert_pages(struct vm_area_struct *vma, unsigned long addr,
2187 struct page **pages, unsigned long *num)
2188{
2189 const unsigned long end_addr = addr + (*num * PAGE_SIZE) - 1;
2190
2191 if (addr < vma->vm_start || end_addr >= vma->vm_end)
2192 return -EFAULT;
2193 if (!(vma->vm_flags & VM_MIXEDMAP)) {
2194 BUG_ON(mmap_read_trylock(vma->vm_mm));
2195 BUG_ON(vma->vm_flags & VM_PFNMAP);
2196 vm_flags_set(vma, VM_MIXEDMAP);
2197 }
2198 /* Defer page refcount checking till we're about to map that page. */
2199 return insert_pages(vma, addr, pages, num, vma->vm_page_prot);
2200}
2201EXPORT_SYMBOL(vm_insert_pages);
2202
2203/**
2204 * vm_insert_page - insert single page into user vma
2205 * @vma: user vma to map to
2206 * @addr: target user address of this page
2207 * @page: source kernel page
2208 *
2209 * This allows drivers to insert individual pages they've allocated
2210 * into a user vma. The zeropage is supported in some VMAs,
2211 * see vm_mixed_zeropage_allowed().
2212 *
2213 * The page has to be a nice clean _individual_ kernel allocation.
2214 * If you allocate a compound page, you need to have marked it as
2215 * such (__GFP_COMP), or manually just split the page up yourself
2216 * (see split_page()).
2217 *
2218 * NOTE! Traditionally this was done with "remap_pfn_range()" which
2219 * took an arbitrary page protection parameter. This doesn't allow
2220 * that. Your vma protection will have to be set up correctly, which
2221 * means that if you want a shared writable mapping, you'd better
2222 * ask for a shared writable mapping!
2223 *
2224 * The page does not need to be reserved.
2225 *
2226 * Usually this function is called from f_op->mmap() handler
2227 * under mm->mmap_lock write-lock, so it can change vma->vm_flags.
2228 * Caller must set VM_MIXEDMAP on vma if it wants to call this
2229 * function from other places, for example from page-fault handler.
2230 *
2231 * Return: %0 on success, negative error code otherwise.
2232 */
2233int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
2234 struct page *page)
2235{
2236 if (addr < vma->vm_start || addr >= vma->vm_end)
2237 return -EFAULT;
2238 if (!(vma->vm_flags & VM_MIXEDMAP)) {
2239 BUG_ON(mmap_read_trylock(vma->vm_mm));
2240 BUG_ON(vma->vm_flags & VM_PFNMAP);
2241 vm_flags_set(vma, VM_MIXEDMAP);
2242 }
2243 return insert_page(vma, addr, page, vma->vm_page_prot);
2244}
2245EXPORT_SYMBOL(vm_insert_page);
2246
2247/*
2248 * __vm_map_pages - maps range of kernel pages into user vma
2249 * @vma: user vma to map to
2250 * @pages: pointer to array of source kernel pages
2251 * @num: number of pages in page array
2252 * @offset: user's requested vm_pgoff
2253 *
2254 * This allows drivers to map range of kernel pages into a user vma.
2255 * The zeropage is supported in some VMAs, see
2256 * vm_mixed_zeropage_allowed().
2257 *
2258 * Return: 0 on success and error code otherwise.
2259 */
2260static int __vm_map_pages(struct vm_area_struct *vma, struct page **pages,
2261 unsigned long num, unsigned long offset)
2262{
2263 unsigned long count = vma_pages(vma);
2264 unsigned long uaddr = vma->vm_start;
2265 int ret, i;
2266
2267 /* Fail if the user requested offset is beyond the end of the object */
2268 if (offset >= num)
2269 return -ENXIO;
2270
2271 /* Fail if the user requested size exceeds available object size */
2272 if (count > num - offset)
2273 return -ENXIO;
2274
2275 for (i = 0; i < count; i++) {
2276 ret = vm_insert_page(vma, uaddr, pages[offset + i]);
2277 if (ret < 0)
2278 return ret;
2279 uaddr += PAGE_SIZE;
2280 }
2281
2282 return 0;
2283}
2284
2285/**
2286 * vm_map_pages - maps range of kernel pages starts with non zero offset
2287 * @vma: user vma to map to
2288 * @pages: pointer to array of source kernel pages
2289 * @num: number of pages in page array
2290 *
2291 * Maps an object consisting of @num pages, catering for the user's
2292 * requested vm_pgoff
2293 *
2294 * If we fail to insert any page into the vma, the function will return
2295 * immediately leaving any previously inserted pages present. Callers
2296 * from the mmap handler may immediately return the error as their caller
2297 * will destroy the vma, removing any successfully inserted pages. Other
2298 * callers should make their own arrangements for calling unmap_region().
2299 *
2300 * Context: Process context. Called by mmap handlers.
2301 * Return: 0 on success and error code otherwise.
2302 */
2303int vm_map_pages(struct vm_area_struct *vma, struct page **pages,
2304 unsigned long num)
2305{
2306 return __vm_map_pages(vma, pages, num, vma->vm_pgoff);
2307}
2308EXPORT_SYMBOL(vm_map_pages);
2309
2310/**
2311 * vm_map_pages_zero - map range of kernel pages starts with zero offset
2312 * @vma: user vma to map to
2313 * @pages: pointer to array of source kernel pages
2314 * @num: number of pages in page array
2315 *
2316 * Similar to vm_map_pages(), except that it explicitly sets the offset
2317 * to 0. This function is intended for the drivers that did not consider
2318 * vm_pgoff.
2319 *
2320 * Context: Process context. Called by mmap handlers.
2321 * Return: 0 on success and error code otherwise.
2322 */
2323int vm_map_pages_zero(struct vm_area_struct *vma, struct page **pages,
2324 unsigned long num)
2325{
2326 return __vm_map_pages(vma, pages, num, 0);
2327}
2328EXPORT_SYMBOL(vm_map_pages_zero);
2329
2330static vm_fault_t insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2331 pfn_t pfn, pgprot_t prot, bool mkwrite)
2332{
2333 struct mm_struct *mm = vma->vm_mm;
2334 pte_t *pte, entry;
2335 spinlock_t *ptl;
2336
2337 pte = get_locked_pte(mm, addr, &ptl);
2338 if (!pte)
2339 return VM_FAULT_OOM;
2340 entry = ptep_get(pte);
2341 if (!pte_none(entry)) {
2342 if (mkwrite) {
2343 /*
2344 * For read faults on private mappings the PFN passed
2345 * in may not match the PFN we have mapped if the
2346 * mapped PFN is a writeable COW page. In the mkwrite
2347 * case we are creating a writable PTE for a shared
2348 * mapping and we expect the PFNs to match. If they
2349 * don't match, we are likely racing with block
2350 * allocation and mapping invalidation so just skip the
2351 * update.
2352 */
2353 if (pte_pfn(entry) != pfn_t_to_pfn(pfn)) {
2354 WARN_ON_ONCE(!is_zero_pfn(pte_pfn(entry)));
2355 goto out_unlock;
2356 }
2357 entry = pte_mkyoung(entry);
2358 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2359 if (ptep_set_access_flags(vma, addr, pte, entry, 1))
2360 update_mmu_cache(vma, addr, pte);
2361 }
2362 goto out_unlock;
2363 }
2364
2365 /* Ok, finally just insert the thing.. */
2366 if (pfn_t_devmap(pfn))
2367 entry = pte_mkdevmap(pfn_t_pte(pfn, prot));
2368 else
2369 entry = pte_mkspecial(pfn_t_pte(pfn, prot));
2370
2371 if (mkwrite) {
2372 entry = pte_mkyoung(entry);
2373 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2374 }
2375
2376 set_pte_at(mm, addr, pte, entry);
2377 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2378
2379out_unlock:
2380 pte_unmap_unlock(pte, ptl);
2381 return VM_FAULT_NOPAGE;
2382}
2383
2384/**
2385 * vmf_insert_pfn_prot - insert single pfn into user vma with specified pgprot
2386 * @vma: user vma to map to
2387 * @addr: target user address of this page
2388 * @pfn: source kernel pfn
2389 * @pgprot: pgprot flags for the inserted page
2390 *
2391 * This is exactly like vmf_insert_pfn(), except that it allows drivers
2392 * to override pgprot on a per-page basis.
2393 *
2394 * This only makes sense for IO mappings, and it makes no sense for
2395 * COW mappings. In general, using multiple vmas is preferable;
2396 * vmf_insert_pfn_prot should only be used if using multiple VMAs is
2397 * impractical.
2398 *
2399 * pgprot typically only differs from @vma->vm_page_prot when drivers set
2400 * caching- and encryption bits different than those of @vma->vm_page_prot,
2401 * because the caching- or encryption mode may not be known at mmap() time.
2402 *
2403 * This is ok as long as @vma->vm_page_prot is not used by the core vm
2404 * to set caching and encryption bits for those vmas (except for COW pages).
2405 * This is ensured by core vm only modifying these page table entries using
2406 * functions that don't touch caching- or encryption bits, using pte_modify()
2407 * if needed. (See for example mprotect()).
2408 *
2409 * Also when new page-table entries are created, this is only done using the
2410 * fault() callback, and never using the value of vma->vm_page_prot,
2411 * except for page-table entries that point to anonymous pages as the result
2412 * of COW.
2413 *
2414 * Context: Process context. May allocate using %GFP_KERNEL.
2415 * Return: vm_fault_t value.
2416 */
2417vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
2418 unsigned long pfn, pgprot_t pgprot)
2419{
2420 /*
2421 * Technically, architectures with pte_special can avoid all these
2422 * restrictions (same for remap_pfn_range). However we would like
2423 * consistency in testing and feature parity among all, so we should
2424 * try to keep these invariants in place for everybody.
2425 */
2426 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
2427 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
2428 (VM_PFNMAP|VM_MIXEDMAP));
2429 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2430 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2431
2432 if (addr < vma->vm_start || addr >= vma->vm_end)
2433 return VM_FAULT_SIGBUS;
2434
2435 if (!pfn_modify_allowed(pfn, pgprot))
2436 return VM_FAULT_SIGBUS;
2437
2438 track_pfn_insert(vma, &pgprot, __pfn_to_pfn_t(pfn, PFN_DEV));
2439
2440 return insert_pfn(vma, addr, __pfn_to_pfn_t(pfn, PFN_DEV), pgprot,
2441 false);
2442}
2443EXPORT_SYMBOL(vmf_insert_pfn_prot);
2444
2445/**
2446 * vmf_insert_pfn - insert single pfn into user vma
2447 * @vma: user vma to map to
2448 * @addr: target user address of this page
2449 * @pfn: source kernel pfn
2450 *
2451 * Similar to vm_insert_page, this allows drivers to insert individual pages
2452 * they've allocated into a user vma. Same comments apply.
2453 *
2454 * This function should only be called from a vm_ops->fault handler, and
2455 * in that case the handler should return the result of this function.
2456 *
2457 * vma cannot be a COW mapping.
2458 *
2459 * As this is called only for pages that do not currently exist, we
2460 * do not need to flush old virtual caches or the TLB.
2461 *
2462 * Context: Process context. May allocate using %GFP_KERNEL.
2463 * Return: vm_fault_t value.
2464 */
2465vm_fault_t vmf_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2466 unsigned long pfn)
2467{
2468 return vmf_insert_pfn_prot(vma, addr, pfn, vma->vm_page_prot);
2469}
2470EXPORT_SYMBOL(vmf_insert_pfn);
2471
2472static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn, bool mkwrite)
2473{
2474 if (unlikely(is_zero_pfn(pfn_t_to_pfn(pfn))) &&
2475 (mkwrite || !vm_mixed_zeropage_allowed(vma)))
2476 return false;
2477 /* these checks mirror the abort conditions in vm_normal_page */
2478 if (vma->vm_flags & VM_MIXEDMAP)
2479 return true;
2480 if (pfn_t_devmap(pfn))
2481 return true;
2482 if (pfn_t_special(pfn))
2483 return true;
2484 if (is_zero_pfn(pfn_t_to_pfn(pfn)))
2485 return true;
2486 return false;
2487}
2488
2489static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
2490 unsigned long addr, pfn_t pfn, bool mkwrite)
2491{
2492 pgprot_t pgprot = vma->vm_page_prot;
2493 int err;
2494
2495 if (!vm_mixed_ok(vma, pfn, mkwrite))
2496 return VM_FAULT_SIGBUS;
2497
2498 if (addr < vma->vm_start || addr >= vma->vm_end)
2499 return VM_FAULT_SIGBUS;
2500
2501 track_pfn_insert(vma, &pgprot, pfn);
2502
2503 if (!pfn_modify_allowed(pfn_t_to_pfn(pfn), pgprot))
2504 return VM_FAULT_SIGBUS;
2505
2506 /*
2507 * If we don't have pte special, then we have to use the pfn_valid()
2508 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2509 * refcount the page if pfn_valid is true (hence insert_page rather
2510 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
2511 * without pte special, it would there be refcounted as a normal page.
2512 */
2513 if (!IS_ENABLED(CONFIG_ARCH_HAS_PTE_SPECIAL) &&
2514 !pfn_t_devmap(pfn) && pfn_t_valid(pfn)) {
2515 struct page *page;
2516
2517 /*
2518 * At this point we are committed to insert_page()
2519 * regardless of whether the caller specified flags that
2520 * result in pfn_t_has_page() == false.
2521 */
2522 page = pfn_to_page(pfn_t_to_pfn(pfn));
2523 err = insert_page(vma, addr, page, pgprot);
2524 } else {
2525 return insert_pfn(vma, addr, pfn, pgprot, mkwrite);
2526 }
2527
2528 if (err == -ENOMEM)
2529 return VM_FAULT_OOM;
2530 if (err < 0 && err != -EBUSY)
2531 return VM_FAULT_SIGBUS;
2532
2533 return VM_FAULT_NOPAGE;
2534}
2535
2536vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2537 pfn_t pfn)
2538{
2539 return __vm_insert_mixed(vma, addr, pfn, false);
2540}
2541EXPORT_SYMBOL(vmf_insert_mixed);
2542
2543/*
2544 * If the insertion of PTE failed because someone else already added a
2545 * different entry in the mean time, we treat that as success as we assume
2546 * the same entry was actually inserted.
2547 */
2548vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
2549 unsigned long addr, pfn_t pfn)
2550{
2551 return __vm_insert_mixed(vma, addr, pfn, true);
2552}
2553
2554/*
2555 * maps a range of physical memory into the requested pages. the old
2556 * mappings are removed. any references to nonexistent pages results
2557 * in null mappings (currently treated as "copy-on-access")
2558 */
2559static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2560 unsigned long addr, unsigned long end,
2561 unsigned long pfn, pgprot_t prot)
2562{
2563 pte_t *pte, *mapped_pte;
2564 spinlock_t *ptl;
2565 int err = 0;
2566
2567 mapped_pte = pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2568 if (!pte)
2569 return -ENOMEM;
2570 arch_enter_lazy_mmu_mode();
2571 do {
2572 BUG_ON(!pte_none(ptep_get(pte)));
2573 if (!pfn_modify_allowed(pfn, prot)) {
2574 err = -EACCES;
2575 break;
2576 }
2577 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2578 pfn++;
2579 } while (pte++, addr += PAGE_SIZE, addr != end);
2580 arch_leave_lazy_mmu_mode();
2581 pte_unmap_unlock(mapped_pte, ptl);
2582 return err;
2583}
2584
2585static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2586 unsigned long addr, unsigned long end,
2587 unsigned long pfn, pgprot_t prot)
2588{
2589 pmd_t *pmd;
2590 unsigned long next;
2591 int err;
2592
2593 pfn -= addr >> PAGE_SHIFT;
2594 pmd = pmd_alloc(mm, pud, addr);
2595 if (!pmd)
2596 return -ENOMEM;
2597 VM_BUG_ON(pmd_trans_huge(*pmd));
2598 do {
2599 next = pmd_addr_end(addr, end);
2600 err = remap_pte_range(mm, pmd, addr, next,
2601 pfn + (addr >> PAGE_SHIFT), prot);
2602 if (err)
2603 return err;
2604 } while (pmd++, addr = next, addr != end);
2605 return 0;
2606}
2607
2608static inline int remap_pud_range(struct mm_struct *mm, p4d_t *p4d,
2609 unsigned long addr, unsigned long end,
2610 unsigned long pfn, pgprot_t prot)
2611{
2612 pud_t *pud;
2613 unsigned long next;
2614 int err;
2615
2616 pfn -= addr >> PAGE_SHIFT;
2617 pud = pud_alloc(mm, p4d, addr);
2618 if (!pud)
2619 return -ENOMEM;
2620 do {
2621 next = pud_addr_end(addr, end);
2622 err = remap_pmd_range(mm, pud, addr, next,
2623 pfn + (addr >> PAGE_SHIFT), prot);
2624 if (err)
2625 return err;
2626 } while (pud++, addr = next, addr != end);
2627 return 0;
2628}
2629
2630static inline int remap_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2631 unsigned long addr, unsigned long end,
2632 unsigned long pfn, pgprot_t prot)
2633{
2634 p4d_t *p4d;
2635 unsigned long next;
2636 int err;
2637
2638 pfn -= addr >> PAGE_SHIFT;
2639 p4d = p4d_alloc(mm, pgd, addr);
2640 if (!p4d)
2641 return -ENOMEM;
2642 do {
2643 next = p4d_addr_end(addr, end);
2644 err = remap_pud_range(mm, p4d, addr, next,
2645 pfn + (addr >> PAGE_SHIFT), prot);
2646 if (err)
2647 return err;
2648 } while (p4d++, addr = next, addr != end);
2649 return 0;
2650}
2651
2652static int remap_pfn_range_internal(struct vm_area_struct *vma, unsigned long addr,
2653 unsigned long pfn, unsigned long size, pgprot_t prot)
2654{
2655 pgd_t *pgd;
2656 unsigned long next;
2657 unsigned long end = addr + PAGE_ALIGN(size);
2658 struct mm_struct *mm = vma->vm_mm;
2659 int err;
2660
2661 if (WARN_ON_ONCE(!PAGE_ALIGNED(addr)))
2662 return -EINVAL;
2663
2664 /*
2665 * Physically remapped pages are special. Tell the
2666 * rest of the world about it:
2667 * VM_IO tells people not to look at these pages
2668 * (accesses can have side effects).
2669 * VM_PFNMAP tells the core MM that the base pages are just
2670 * raw PFN mappings, and do not have a "struct page" associated
2671 * with them.
2672 * VM_DONTEXPAND
2673 * Disable vma merging and expanding with mremap().
2674 * VM_DONTDUMP
2675 * Omit vma from core dump, even when VM_IO turned off.
2676 *
2677 * There's a horrible special case to handle copy-on-write
2678 * behaviour that some programs depend on. We mark the "original"
2679 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2680 * See vm_normal_page() for details.
2681 */
2682 if (is_cow_mapping(vma->vm_flags)) {
2683 if (addr != vma->vm_start || end != vma->vm_end)
2684 return -EINVAL;
2685 vma->vm_pgoff = pfn;
2686 }
2687
2688 vm_flags_set(vma, VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP);
2689
2690 BUG_ON(addr >= end);
2691 pfn -= addr >> PAGE_SHIFT;
2692 pgd = pgd_offset(mm, addr);
2693 flush_cache_range(vma, addr, end);
2694 do {
2695 next = pgd_addr_end(addr, end);
2696 err = remap_p4d_range(mm, pgd, addr, next,
2697 pfn + (addr >> PAGE_SHIFT), prot);
2698 if (err)
2699 return err;
2700 } while (pgd++, addr = next, addr != end);
2701
2702 return 0;
2703}
2704
2705/*
2706 * Variant of remap_pfn_range that does not call track_pfn_remap. The caller
2707 * must have pre-validated the caching bits of the pgprot_t.
2708 */
2709int remap_pfn_range_notrack(struct vm_area_struct *vma, unsigned long addr,
2710 unsigned long pfn, unsigned long size, pgprot_t prot)
2711{
2712 int error = remap_pfn_range_internal(vma, addr, pfn, size, prot);
2713
2714 if (!error)
2715 return 0;
2716
2717 /*
2718 * A partial pfn range mapping is dangerous: it does not
2719 * maintain page reference counts, and callers may free
2720 * pages due to the error. So zap it early.
2721 */
2722 zap_page_range_single(vma, addr, size, NULL);
2723 return error;
2724}
2725
2726/**
2727 * remap_pfn_range - remap kernel memory to userspace
2728 * @vma: user vma to map to
2729 * @addr: target page aligned user address to start at
2730 * @pfn: page frame number of kernel physical memory address
2731 * @size: size of mapping area
2732 * @prot: page protection flags for this mapping
2733 *
2734 * Note: this is only safe if the mm semaphore is held when called.
2735 *
2736 * Return: %0 on success, negative error code otherwise.
2737 */
2738int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2739 unsigned long pfn, unsigned long size, pgprot_t prot)
2740{
2741 int err;
2742
2743 err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
2744 if (err)
2745 return -EINVAL;
2746
2747 err = remap_pfn_range_notrack(vma, addr, pfn, size, prot);
2748 if (err)
2749 untrack_pfn(vma, pfn, PAGE_ALIGN(size), true);
2750 return err;
2751}
2752EXPORT_SYMBOL(remap_pfn_range);
2753
2754/**
2755 * vm_iomap_memory - remap memory to userspace
2756 * @vma: user vma to map to
2757 * @start: start of the physical memory to be mapped
2758 * @len: size of area
2759 *
2760 * This is a simplified io_remap_pfn_range() for common driver use. The
2761 * driver just needs to give us the physical memory range to be mapped,
2762 * we'll figure out the rest from the vma information.
2763 *
2764 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2765 * whatever write-combining details or similar.
2766 *
2767 * Return: %0 on success, negative error code otherwise.
2768 */
2769int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2770{
2771 unsigned long vm_len, pfn, pages;
2772
2773 /* Check that the physical memory area passed in looks valid */
2774 if (start + len < start)
2775 return -EINVAL;
2776 /*
2777 * You *really* shouldn't map things that aren't page-aligned,
2778 * but we've historically allowed it because IO memory might
2779 * just have smaller alignment.
2780 */
2781 len += start & ~PAGE_MASK;
2782 pfn = start >> PAGE_SHIFT;
2783 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2784 if (pfn + pages < pfn)
2785 return -EINVAL;
2786
2787 /* We start the mapping 'vm_pgoff' pages into the area */
2788 if (vma->vm_pgoff > pages)
2789 return -EINVAL;
2790 pfn += vma->vm_pgoff;
2791 pages -= vma->vm_pgoff;
2792
2793 /* Can we fit all of the mapping? */
2794 vm_len = vma->vm_end - vma->vm_start;
2795 if (vm_len >> PAGE_SHIFT > pages)
2796 return -EINVAL;
2797
2798 /* Ok, let it rip */
2799 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2800}
2801EXPORT_SYMBOL(vm_iomap_memory);
2802
2803static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2804 unsigned long addr, unsigned long end,
2805 pte_fn_t fn, void *data, bool create,
2806 pgtbl_mod_mask *mask)
2807{
2808 pte_t *pte, *mapped_pte;
2809 int err = 0;
2810 spinlock_t *ptl;
2811
2812 if (create) {
2813 mapped_pte = pte = (mm == &init_mm) ?
2814 pte_alloc_kernel_track(pmd, addr, mask) :
2815 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2816 if (!pte)
2817 return -ENOMEM;
2818 } else {
2819 mapped_pte = pte = (mm == &init_mm) ?
2820 pte_offset_kernel(pmd, addr) :
2821 pte_offset_map_lock(mm, pmd, addr, &ptl);
2822 if (!pte)
2823 return -EINVAL;
2824 }
2825
2826 arch_enter_lazy_mmu_mode();
2827
2828 if (fn) {
2829 do {
2830 if (create || !pte_none(ptep_get(pte))) {
2831 err = fn(pte++, addr, data);
2832 if (err)
2833 break;
2834 }
2835 } while (addr += PAGE_SIZE, addr != end);
2836 }
2837 *mask |= PGTBL_PTE_MODIFIED;
2838
2839 arch_leave_lazy_mmu_mode();
2840
2841 if (mm != &init_mm)
2842 pte_unmap_unlock(mapped_pte, ptl);
2843 return err;
2844}
2845
2846static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2847 unsigned long addr, unsigned long end,
2848 pte_fn_t fn, void *data, bool create,
2849 pgtbl_mod_mask *mask)
2850{
2851 pmd_t *pmd;
2852 unsigned long next;
2853 int err = 0;
2854
2855 BUG_ON(pud_leaf(*pud));
2856
2857 if (create) {
2858 pmd = pmd_alloc_track(mm, pud, addr, mask);
2859 if (!pmd)
2860 return -ENOMEM;
2861 } else {
2862 pmd = pmd_offset(pud, addr);
2863 }
2864 do {
2865 next = pmd_addr_end(addr, end);
2866 if (pmd_none(*pmd) && !create)
2867 continue;
2868 if (WARN_ON_ONCE(pmd_leaf(*pmd)))
2869 return -EINVAL;
2870 if (!pmd_none(*pmd) && WARN_ON_ONCE(pmd_bad(*pmd))) {
2871 if (!create)
2872 continue;
2873 pmd_clear_bad(pmd);
2874 }
2875 err = apply_to_pte_range(mm, pmd, addr, next,
2876 fn, data, create, mask);
2877 if (err)
2878 break;
2879 } while (pmd++, addr = next, addr != end);
2880
2881 return err;
2882}
2883
2884static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
2885 unsigned long addr, unsigned long end,
2886 pte_fn_t fn, void *data, bool create,
2887 pgtbl_mod_mask *mask)
2888{
2889 pud_t *pud;
2890 unsigned long next;
2891 int err = 0;
2892
2893 if (create) {
2894 pud = pud_alloc_track(mm, p4d, addr, mask);
2895 if (!pud)
2896 return -ENOMEM;
2897 } else {
2898 pud = pud_offset(p4d, addr);
2899 }
2900 do {
2901 next = pud_addr_end(addr, end);
2902 if (pud_none(*pud) && !create)
2903 continue;
2904 if (WARN_ON_ONCE(pud_leaf(*pud)))
2905 return -EINVAL;
2906 if (!pud_none(*pud) && WARN_ON_ONCE(pud_bad(*pud))) {
2907 if (!create)
2908 continue;
2909 pud_clear_bad(pud);
2910 }
2911 err = apply_to_pmd_range(mm, pud, addr, next,
2912 fn, data, create, mask);
2913 if (err)
2914 break;
2915 } while (pud++, addr = next, addr != end);
2916
2917 return err;
2918}
2919
2920static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
2921 unsigned long addr, unsigned long end,
2922 pte_fn_t fn, void *data, bool create,
2923 pgtbl_mod_mask *mask)
2924{
2925 p4d_t *p4d;
2926 unsigned long next;
2927 int err = 0;
2928
2929 if (create) {
2930 p4d = p4d_alloc_track(mm, pgd, addr, mask);
2931 if (!p4d)
2932 return -ENOMEM;
2933 } else {
2934 p4d = p4d_offset(pgd, addr);
2935 }
2936 do {
2937 next = p4d_addr_end(addr, end);
2938 if (p4d_none(*p4d) && !create)
2939 continue;
2940 if (WARN_ON_ONCE(p4d_leaf(*p4d)))
2941 return -EINVAL;
2942 if (!p4d_none(*p4d) && WARN_ON_ONCE(p4d_bad(*p4d))) {
2943 if (!create)
2944 continue;
2945 p4d_clear_bad(p4d);
2946 }
2947 err = apply_to_pud_range(mm, p4d, addr, next,
2948 fn, data, create, mask);
2949 if (err)
2950 break;
2951 } while (p4d++, addr = next, addr != end);
2952
2953 return err;
2954}
2955
2956static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2957 unsigned long size, pte_fn_t fn,
2958 void *data, bool create)
2959{
2960 pgd_t *pgd;
2961 unsigned long start = addr, next;
2962 unsigned long end = addr + size;
2963 pgtbl_mod_mask mask = 0;
2964 int err = 0;
2965
2966 if (WARN_ON(addr >= end))
2967 return -EINVAL;
2968
2969 pgd = pgd_offset(mm, addr);
2970 do {
2971 next = pgd_addr_end(addr, end);
2972 if (pgd_none(*pgd) && !create)
2973 continue;
2974 if (WARN_ON_ONCE(pgd_leaf(*pgd))) {
2975 err = -EINVAL;
2976 break;
2977 }
2978 if (!pgd_none(*pgd) && WARN_ON_ONCE(pgd_bad(*pgd))) {
2979 if (!create)
2980 continue;
2981 pgd_clear_bad(pgd);
2982 }
2983 err = apply_to_p4d_range(mm, pgd, addr, next,
2984 fn, data, create, &mask);
2985 if (err)
2986 break;
2987 } while (pgd++, addr = next, addr != end);
2988
2989 if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
2990 arch_sync_kernel_mappings(start, start + size);
2991
2992 return err;
2993}
2994
2995/*
2996 * Scan a region of virtual memory, filling in page tables as necessary
2997 * and calling a provided function on each leaf page table.
2998 */
2999int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
3000 unsigned long size, pte_fn_t fn, void *data)
3001{
3002 return __apply_to_page_range(mm, addr, size, fn, data, true);
3003}
3004EXPORT_SYMBOL_GPL(apply_to_page_range);
3005
3006/*
3007 * Scan a region of virtual memory, calling a provided function on
3008 * each leaf page table where it exists.
3009 *
3010 * Unlike apply_to_page_range, this does _not_ fill in page tables
3011 * where they are absent.
3012 */
3013int apply_to_existing_page_range(struct mm_struct *mm, unsigned long addr,
3014 unsigned long size, pte_fn_t fn, void *data)
3015{
3016 return __apply_to_page_range(mm, addr, size, fn, data, false);
3017}
3018EXPORT_SYMBOL_GPL(apply_to_existing_page_range);
3019
3020/*
3021 * handle_pte_fault chooses page fault handler according to an entry which was
3022 * read non-atomically. Before making any commitment, on those architectures
3023 * or configurations (e.g. i386 with PAE) which might give a mix of unmatched
3024 * parts, do_swap_page must check under lock before unmapping the pte and
3025 * proceeding (but do_wp_page is only called after already making such a check;
3026 * and do_anonymous_page can safely check later on).
3027 */
3028static inline int pte_unmap_same(struct vm_fault *vmf)
3029{
3030 int same = 1;
3031#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPTION)
3032 if (sizeof(pte_t) > sizeof(unsigned long)) {
3033 spin_lock(vmf->ptl);
3034 same = pte_same(ptep_get(vmf->pte), vmf->orig_pte);
3035 spin_unlock(vmf->ptl);
3036 }
3037#endif
3038 pte_unmap(vmf->pte);
3039 vmf->pte = NULL;
3040 return same;
3041}
3042
3043/*
3044 * Return:
3045 * 0: copied succeeded
3046 * -EHWPOISON: copy failed due to hwpoison in source page
3047 * -EAGAIN: copied failed (some other reason)
3048 */
3049static inline int __wp_page_copy_user(struct page *dst, struct page *src,
3050 struct vm_fault *vmf)
3051{
3052 int ret;
3053 void *kaddr;
3054 void __user *uaddr;
3055 struct vm_area_struct *vma = vmf->vma;
3056 struct mm_struct *mm = vma->vm_mm;
3057 unsigned long addr = vmf->address;
3058
3059 if (likely(src)) {
3060 if (copy_mc_user_highpage(dst, src, addr, vma))
3061 return -EHWPOISON;
3062 return 0;
3063 }
3064
3065 /*
3066 * If the source page was a PFN mapping, we don't have
3067 * a "struct page" for it. We do a best-effort copy by
3068 * just copying from the original user address. If that
3069 * fails, we just zero-fill it. Live with it.
3070 */
3071 kaddr = kmap_local_page(dst);
3072 pagefault_disable();
3073 uaddr = (void __user *)(addr & PAGE_MASK);
3074
3075 /*
3076 * On architectures with software "accessed" bits, we would
3077 * take a double page fault, so mark it accessed here.
3078 */
3079 vmf->pte = NULL;
3080 if (!arch_has_hw_pte_young() && !pte_young(vmf->orig_pte)) {
3081 pte_t entry;
3082
3083 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
3084 if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte))) {
3085 /*
3086 * Other thread has already handled the fault
3087 * and update local tlb only
3088 */
3089 if (vmf->pte)
3090 update_mmu_tlb(vma, addr, vmf->pte);
3091 ret = -EAGAIN;
3092 goto pte_unlock;
3093 }
3094
3095 entry = pte_mkyoung(vmf->orig_pte);
3096 if (ptep_set_access_flags(vma, addr, vmf->pte, entry, 0))
3097 update_mmu_cache_range(vmf, vma, addr, vmf->pte, 1);
3098 }
3099
3100 /*
3101 * This really shouldn't fail, because the page is there
3102 * in the page tables. But it might just be unreadable,
3103 * in which case we just give up and fill the result with
3104 * zeroes.
3105 */
3106 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
3107 if (vmf->pte)
3108 goto warn;
3109
3110 /* Re-validate under PTL if the page is still mapped */
3111 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, addr, &vmf->ptl);
3112 if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte))) {
3113 /* The PTE changed under us, update local tlb */
3114 if (vmf->pte)
3115 update_mmu_tlb(vma, addr, vmf->pte);
3116 ret = -EAGAIN;
3117 goto pte_unlock;
3118 }
3119
3120 /*
3121 * The same page can be mapped back since last copy attempt.
3122 * Try to copy again under PTL.
3123 */
3124 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE)) {
3125 /*
3126 * Give a warn in case there can be some obscure
3127 * use-case
3128 */
3129warn:
3130 WARN_ON_ONCE(1);
3131 clear_page(kaddr);
3132 }
3133 }
3134
3135 ret = 0;
3136
3137pte_unlock:
3138 if (vmf->pte)
3139 pte_unmap_unlock(vmf->pte, vmf->ptl);
3140 pagefault_enable();
3141 kunmap_local(kaddr);
3142 flush_dcache_page(dst);
3143
3144 return ret;
3145}
3146
3147static gfp_t __get_fault_gfp_mask(struct vm_area_struct *vma)
3148{
3149 struct file *vm_file = vma->vm_file;
3150
3151 if (vm_file)
3152 return mapping_gfp_mask(vm_file->f_mapping) | __GFP_FS | __GFP_IO;
3153
3154 /*
3155 * Special mappings (e.g. VDSO) do not have any file so fake
3156 * a default GFP_KERNEL for them.
3157 */
3158 return GFP_KERNEL;
3159}
3160
3161/*
3162 * Notify the address space that the page is about to become writable so that
3163 * it can prohibit this or wait for the page to get into an appropriate state.
3164 *
3165 * We do this without the lock held, so that it can sleep if it needs to.
3166 */
3167static vm_fault_t do_page_mkwrite(struct vm_fault *vmf, struct folio *folio)
3168{
3169 vm_fault_t ret;
3170 unsigned int old_flags = vmf->flags;
3171
3172 vmf->flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
3173
3174 if (vmf->vma->vm_file &&
3175 IS_SWAPFILE(vmf->vma->vm_file->f_mapping->host))
3176 return VM_FAULT_SIGBUS;
3177
3178 ret = vmf->vma->vm_ops->page_mkwrite(vmf);
3179 /* Restore original flags so that caller is not surprised */
3180 vmf->flags = old_flags;
3181 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
3182 return ret;
3183 if (unlikely(!(ret & VM_FAULT_LOCKED))) {
3184 folio_lock(folio);
3185 if (!folio->mapping) {
3186 folio_unlock(folio);
3187 return 0; /* retry */
3188 }
3189 ret |= VM_FAULT_LOCKED;
3190 } else
3191 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
3192 return ret;
3193}
3194
3195/*
3196 * Handle dirtying of a page in shared file mapping on a write fault.
3197 *
3198 * The function expects the page to be locked and unlocks it.
3199 */
3200static vm_fault_t fault_dirty_shared_page(struct vm_fault *vmf)
3201{
3202 struct vm_area_struct *vma = vmf->vma;
3203 struct address_space *mapping;
3204 struct folio *folio = page_folio(vmf->page);
3205 bool dirtied;
3206 bool page_mkwrite = vma->vm_ops && vma->vm_ops->page_mkwrite;
3207
3208 dirtied = folio_mark_dirty(folio);
3209 VM_BUG_ON_FOLIO(folio_test_anon(folio), folio);
3210 /*
3211 * Take a local copy of the address_space - folio.mapping may be zeroed
3212 * by truncate after folio_unlock(). The address_space itself remains
3213 * pinned by vma->vm_file's reference. We rely on folio_unlock()'s
3214 * release semantics to prevent the compiler from undoing this copying.
3215 */
3216 mapping = folio_raw_mapping(folio);
3217 folio_unlock(folio);
3218
3219 if (!page_mkwrite)
3220 file_update_time(vma->vm_file);
3221
3222 /*
3223 * Throttle page dirtying rate down to writeback speed.
3224 *
3225 * mapping may be NULL here because some device drivers do not
3226 * set page.mapping but still dirty their pages
3227 *
3228 * Drop the mmap_lock before waiting on IO, if we can. The file
3229 * is pinning the mapping, as per above.
3230 */
3231 if ((dirtied || page_mkwrite) && mapping) {
3232 struct file *fpin;
3233
3234 fpin = maybe_unlock_mmap_for_io(vmf, NULL);
3235 balance_dirty_pages_ratelimited(mapping);
3236 if (fpin) {
3237 fput(fpin);
3238 return VM_FAULT_COMPLETED;
3239 }
3240 }
3241
3242 return 0;
3243}
3244
3245/*
3246 * Handle write page faults for pages that can be reused in the current vma
3247 *
3248 * This can happen either due to the mapping being with the VM_SHARED flag,
3249 * or due to us being the last reference standing to the page. In either
3250 * case, all we need to do here is to mark the page as writable and update
3251 * any related book-keeping.
3252 */
3253static inline void wp_page_reuse(struct vm_fault *vmf, struct folio *folio)
3254 __releases(vmf->ptl)
3255{
3256 struct vm_area_struct *vma = vmf->vma;
3257 pte_t entry;
3258
3259 VM_BUG_ON(!(vmf->flags & FAULT_FLAG_WRITE));
3260 VM_WARN_ON(is_zero_pfn(pte_pfn(vmf->orig_pte)));
3261
3262 if (folio) {
3263 VM_BUG_ON(folio_test_anon(folio) &&
3264 !PageAnonExclusive(vmf->page));
3265 /*
3266 * Clear the folio's cpupid information as the existing
3267 * information potentially belongs to a now completely
3268 * unrelated process.
3269 */
3270 folio_xchg_last_cpupid(folio, (1 << LAST_CPUPID_SHIFT) - 1);
3271 }
3272
3273 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
3274 entry = pte_mkyoung(vmf->orig_pte);
3275 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3276 if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
3277 update_mmu_cache_range(vmf, vma, vmf->address, vmf->pte, 1);
3278 pte_unmap_unlock(vmf->pte, vmf->ptl);
3279 count_vm_event(PGREUSE);
3280}
3281
3282/*
3283 * We could add a bitflag somewhere, but for now, we know that all
3284 * vm_ops that have a ->map_pages have been audited and don't need
3285 * the mmap_lock to be held.
3286 */
3287static inline vm_fault_t vmf_can_call_fault(const struct vm_fault *vmf)
3288{
3289 struct vm_area_struct *vma = vmf->vma;
3290
3291 if (vma->vm_ops->map_pages || !(vmf->flags & FAULT_FLAG_VMA_LOCK))
3292 return 0;
3293 vma_end_read(vma);
3294 return VM_FAULT_RETRY;
3295}
3296
3297/**
3298 * __vmf_anon_prepare - Prepare to handle an anonymous fault.
3299 * @vmf: The vm_fault descriptor passed from the fault handler.
3300 *
3301 * When preparing to insert an anonymous page into a VMA from a
3302 * fault handler, call this function rather than anon_vma_prepare().
3303 * If this vma does not already have an associated anon_vma and we are
3304 * only protected by the per-VMA lock, the caller must retry with the
3305 * mmap_lock held. __anon_vma_prepare() will look at adjacent VMAs to
3306 * determine if this VMA can share its anon_vma, and that's not safe to
3307 * do with only the per-VMA lock held for this VMA.
3308 *
3309 * Return: 0 if fault handling can proceed. Any other value should be
3310 * returned to the caller.
3311 */
3312vm_fault_t __vmf_anon_prepare(struct vm_fault *vmf)
3313{
3314 struct vm_area_struct *vma = vmf->vma;
3315 vm_fault_t ret = 0;
3316
3317 if (likely(vma->anon_vma))
3318 return 0;
3319 if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
3320 if (!mmap_read_trylock(vma->vm_mm))
3321 return VM_FAULT_RETRY;
3322 }
3323 if (__anon_vma_prepare(vma))
3324 ret = VM_FAULT_OOM;
3325 if (vmf->flags & FAULT_FLAG_VMA_LOCK)
3326 mmap_read_unlock(vma->vm_mm);
3327 return ret;
3328}
3329
3330/*
3331 * Handle the case of a page which we actually need to copy to a new page,
3332 * either due to COW or unsharing.
3333 *
3334 * Called with mmap_lock locked and the old page referenced, but
3335 * without the ptl held.
3336 *
3337 * High level logic flow:
3338 *
3339 * - Allocate a page, copy the content of the old page to the new one.
3340 * - Handle book keeping and accounting - cgroups, mmu-notifiers, etc.
3341 * - Take the PTL. If the pte changed, bail out and release the allocated page
3342 * - If the pte is still the way we remember it, update the page table and all
3343 * relevant references. This includes dropping the reference the page-table
3344 * held to the old page, as well as updating the rmap.
3345 * - In any case, unlock the PTL and drop the reference we took to the old page.
3346 */
3347static vm_fault_t wp_page_copy(struct vm_fault *vmf)
3348{
3349 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
3350 struct vm_area_struct *vma = vmf->vma;
3351 struct mm_struct *mm = vma->vm_mm;
3352 struct folio *old_folio = NULL;
3353 struct folio *new_folio = NULL;
3354 pte_t entry;
3355 int page_copied = 0;
3356 struct mmu_notifier_range range;
3357 vm_fault_t ret;
3358 bool pfn_is_zero;
3359
3360 delayacct_wpcopy_start();
3361
3362 if (vmf->page)
3363 old_folio = page_folio(vmf->page);
3364 ret = vmf_anon_prepare(vmf);
3365 if (unlikely(ret))
3366 goto out;
3367
3368 pfn_is_zero = is_zero_pfn(pte_pfn(vmf->orig_pte));
3369 new_folio = folio_prealloc(mm, vma, vmf->address, pfn_is_zero);
3370 if (!new_folio)
3371 goto oom;
3372
3373 if (!pfn_is_zero) {
3374 int err;
3375
3376 err = __wp_page_copy_user(&new_folio->page, vmf->page, vmf);
3377 if (err) {
3378 /*
3379 * COW failed, if the fault was solved by other,
3380 * it's fine. If not, userspace would re-fault on
3381 * the same address and we will handle the fault
3382 * from the second attempt.
3383 * The -EHWPOISON case will not be retried.
3384 */
3385 folio_put(new_folio);
3386 if (old_folio)
3387 folio_put(old_folio);
3388
3389 delayacct_wpcopy_end();
3390 return err == -EHWPOISON ? VM_FAULT_HWPOISON : 0;
3391 }
3392 kmsan_copy_page_meta(&new_folio->page, vmf->page);
3393 }
3394
3395 __folio_mark_uptodate(new_folio);
3396
3397 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm,
3398 vmf->address & PAGE_MASK,
3399 (vmf->address & PAGE_MASK) + PAGE_SIZE);
3400 mmu_notifier_invalidate_range_start(&range);
3401
3402 /*
3403 * Re-check the pte - we dropped the lock
3404 */
3405 vmf->pte = pte_offset_map_lock(mm, vmf->pmd, vmf->address, &vmf->ptl);
3406 if (likely(vmf->pte && pte_same(ptep_get(vmf->pte), vmf->orig_pte))) {
3407 if (old_folio) {
3408 if (!folio_test_anon(old_folio)) {
3409 dec_mm_counter(mm, mm_counter_file(old_folio));
3410 inc_mm_counter(mm, MM_ANONPAGES);
3411 }
3412 } else {
3413 ksm_might_unmap_zero_page(mm, vmf->orig_pte);
3414 inc_mm_counter(mm, MM_ANONPAGES);
3415 }
3416 flush_cache_page(vma, vmf->address, pte_pfn(vmf->orig_pte));
3417 entry = mk_pte(&new_folio->page, vma->vm_page_prot);
3418 entry = pte_sw_mkyoung(entry);
3419 if (unlikely(unshare)) {
3420 if (pte_soft_dirty(vmf->orig_pte))
3421 entry = pte_mksoft_dirty(entry);
3422 if (pte_uffd_wp(vmf->orig_pte))
3423 entry = pte_mkuffd_wp(entry);
3424 } else {
3425 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3426 }
3427
3428 /*
3429 * Clear the pte entry and flush it first, before updating the
3430 * pte with the new entry, to keep TLBs on different CPUs in
3431 * sync. This code used to set the new PTE then flush TLBs, but
3432 * that left a window where the new PTE could be loaded into
3433 * some TLBs while the old PTE remains in others.
3434 */
3435 ptep_clear_flush(vma, vmf->address, vmf->pte);
3436 folio_add_new_anon_rmap(new_folio, vma, vmf->address, RMAP_EXCLUSIVE);
3437 folio_add_lru_vma(new_folio, vma);
3438 BUG_ON(unshare && pte_write(entry));
3439 set_pte_at(mm, vmf->address, vmf->pte, entry);
3440 update_mmu_cache_range(vmf, vma, vmf->address, vmf->pte, 1);
3441 if (old_folio) {
3442 /*
3443 * Only after switching the pte to the new page may
3444 * we remove the mapcount here. Otherwise another
3445 * process may come and find the rmap count decremented
3446 * before the pte is switched to the new page, and
3447 * "reuse" the old page writing into it while our pte
3448 * here still points into it and can be read by other
3449 * threads.
3450 *
3451 * The critical issue is to order this
3452 * folio_remove_rmap_pte() with the ptp_clear_flush
3453 * above. Those stores are ordered by (if nothing else,)
3454 * the barrier present in the atomic_add_negative
3455 * in folio_remove_rmap_pte();
3456 *
3457 * Then the TLB flush in ptep_clear_flush ensures that
3458 * no process can access the old page before the
3459 * decremented mapcount is visible. And the old page
3460 * cannot be reused until after the decremented
3461 * mapcount is visible. So transitively, TLBs to
3462 * old page will be flushed before it can be reused.
3463 */
3464 folio_remove_rmap_pte(old_folio, vmf->page, vma);
3465 }
3466
3467 /* Free the old page.. */
3468 new_folio = old_folio;
3469 page_copied = 1;
3470 pte_unmap_unlock(vmf->pte, vmf->ptl);
3471 } else if (vmf->pte) {
3472 update_mmu_tlb(vma, vmf->address, vmf->pte);
3473 pte_unmap_unlock(vmf->pte, vmf->ptl);
3474 }
3475
3476 mmu_notifier_invalidate_range_end(&range);
3477
3478 if (new_folio)
3479 folio_put(new_folio);
3480 if (old_folio) {
3481 if (page_copied)
3482 free_swap_cache(old_folio);
3483 folio_put(old_folio);
3484 }
3485
3486 delayacct_wpcopy_end();
3487 return 0;
3488oom:
3489 ret = VM_FAULT_OOM;
3490out:
3491 if (old_folio)
3492 folio_put(old_folio);
3493
3494 delayacct_wpcopy_end();
3495 return ret;
3496}
3497
3498/**
3499 * finish_mkwrite_fault - finish page fault for a shared mapping, making PTE
3500 * writeable once the page is prepared
3501 *
3502 * @vmf: structure describing the fault
3503 * @folio: the folio of vmf->page
3504 *
3505 * This function handles all that is needed to finish a write page fault in a
3506 * shared mapping due to PTE being read-only once the mapped page is prepared.
3507 * It handles locking of PTE and modifying it.
3508 *
3509 * The function expects the page to be locked or other protection against
3510 * concurrent faults / writeback (such as DAX radix tree locks).
3511 *
3512 * Return: %0 on success, %VM_FAULT_NOPAGE when PTE got changed before
3513 * we acquired PTE lock.
3514 */
3515static vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf, struct folio *folio)
3516{
3517 WARN_ON_ONCE(!(vmf->vma->vm_flags & VM_SHARED));
3518 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd, vmf->address,
3519 &vmf->ptl);
3520 if (!vmf->pte)
3521 return VM_FAULT_NOPAGE;
3522 /*
3523 * We might have raced with another page fault while we released the
3524 * pte_offset_map_lock.
3525 */
3526 if (!pte_same(ptep_get(vmf->pte), vmf->orig_pte)) {
3527 update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
3528 pte_unmap_unlock(vmf->pte, vmf->ptl);
3529 return VM_FAULT_NOPAGE;
3530 }
3531 wp_page_reuse(vmf, folio);
3532 return 0;
3533}
3534
3535/*
3536 * Handle write page faults for VM_MIXEDMAP or VM_PFNMAP for a VM_SHARED
3537 * mapping
3538 */
3539static vm_fault_t wp_pfn_shared(struct vm_fault *vmf)
3540{
3541 struct vm_area_struct *vma = vmf->vma;
3542
3543 if (vma->vm_ops && vma->vm_ops->pfn_mkwrite) {
3544 vm_fault_t ret;
3545
3546 pte_unmap_unlock(vmf->pte, vmf->ptl);
3547 ret = vmf_can_call_fault(vmf);
3548 if (ret)
3549 return ret;
3550
3551 vmf->flags |= FAULT_FLAG_MKWRITE;
3552 ret = vma->vm_ops->pfn_mkwrite(vmf);
3553 if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))
3554 return ret;
3555 return finish_mkwrite_fault(vmf, NULL);
3556 }
3557 wp_page_reuse(vmf, NULL);
3558 return 0;
3559}
3560
3561static vm_fault_t wp_page_shared(struct vm_fault *vmf, struct folio *folio)
3562 __releases(vmf->ptl)
3563{
3564 struct vm_area_struct *vma = vmf->vma;
3565 vm_fault_t ret = 0;
3566
3567 folio_get(folio);
3568
3569 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
3570 vm_fault_t tmp;
3571
3572 pte_unmap_unlock(vmf->pte, vmf->ptl);
3573 tmp = vmf_can_call_fault(vmf);
3574 if (tmp) {
3575 folio_put(folio);
3576 return tmp;
3577 }
3578
3579 tmp = do_page_mkwrite(vmf, folio);
3580 if (unlikely(!tmp || (tmp &
3581 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3582 folio_put(folio);
3583 return tmp;
3584 }
3585 tmp = finish_mkwrite_fault(vmf, folio);
3586 if (unlikely(tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) {
3587 folio_unlock(folio);
3588 folio_put(folio);
3589 return tmp;
3590 }
3591 } else {
3592 wp_page_reuse(vmf, folio);
3593 folio_lock(folio);
3594 }
3595 ret |= fault_dirty_shared_page(vmf);
3596 folio_put(folio);
3597
3598 return ret;
3599}
3600
3601static bool wp_can_reuse_anon_folio(struct folio *folio,
3602 struct vm_area_struct *vma)
3603{
3604 /*
3605 * We could currently only reuse a subpage of a large folio if no
3606 * other subpages of the large folios are still mapped. However,
3607 * let's just consistently not reuse subpages even if we could
3608 * reuse in that scenario, and give back a large folio a bit
3609 * sooner.
3610 */
3611 if (folio_test_large(folio))
3612 return false;
3613
3614 /*
3615 * We have to verify under folio lock: these early checks are
3616 * just an optimization to avoid locking the folio and freeing
3617 * the swapcache if there is little hope that we can reuse.
3618 *
3619 * KSM doesn't necessarily raise the folio refcount.
3620 */
3621 if (folio_test_ksm(folio) || folio_ref_count(folio) > 3)
3622 return false;
3623 if (!folio_test_lru(folio))
3624 /*
3625 * We cannot easily detect+handle references from
3626 * remote LRU caches or references to LRU folios.
3627 */
3628 lru_add_drain();
3629 if (folio_ref_count(folio) > 1 + folio_test_swapcache(folio))
3630 return false;
3631 if (!folio_trylock(folio))
3632 return false;
3633 if (folio_test_swapcache(folio))
3634 folio_free_swap(folio);
3635 if (folio_test_ksm(folio) || folio_ref_count(folio) != 1) {
3636 folio_unlock(folio);
3637 return false;
3638 }
3639 /*
3640 * Ok, we've got the only folio reference from our mapping
3641 * and the folio is locked, it's dark out, and we're wearing
3642 * sunglasses. Hit it.
3643 */
3644 folio_move_anon_rmap(folio, vma);
3645 folio_unlock(folio);
3646 return true;
3647}
3648
3649/*
3650 * This routine handles present pages, when
3651 * * users try to write to a shared page (FAULT_FLAG_WRITE)
3652 * * GUP wants to take a R/O pin on a possibly shared anonymous page
3653 * (FAULT_FLAG_UNSHARE)
3654 *
3655 * It is done by copying the page to a new address and decrementing the
3656 * shared-page counter for the old page.
3657 *
3658 * Note that this routine assumes that the protection checks have been
3659 * done by the caller (the low-level page fault routine in most cases).
3660 * Thus, with FAULT_FLAG_WRITE, we can safely just mark it writable once we've
3661 * done any necessary COW.
3662 *
3663 * In case of FAULT_FLAG_WRITE, we also mark the page dirty at this point even
3664 * though the page will change only once the write actually happens. This
3665 * avoids a few races, and potentially makes it more efficient.
3666 *
3667 * We enter with non-exclusive mmap_lock (to exclude vma changes,
3668 * but allow concurrent faults), with pte both mapped and locked.
3669 * We return with mmap_lock still held, but pte unmapped and unlocked.
3670 */
3671static vm_fault_t do_wp_page(struct vm_fault *vmf)
3672 __releases(vmf->ptl)
3673{
3674 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
3675 struct vm_area_struct *vma = vmf->vma;
3676 struct folio *folio = NULL;
3677 pte_t pte;
3678
3679 if (likely(!unshare)) {
3680 if (userfaultfd_pte_wp(vma, ptep_get(vmf->pte))) {
3681 if (!userfaultfd_wp_async(vma)) {
3682 pte_unmap_unlock(vmf->pte, vmf->ptl);
3683 return handle_userfault(vmf, VM_UFFD_WP);
3684 }
3685
3686 /*
3687 * Nothing needed (cache flush, TLB invalidations,
3688 * etc.) because we're only removing the uffd-wp bit,
3689 * which is completely invisible to the user.
3690 */
3691 pte = pte_clear_uffd_wp(ptep_get(vmf->pte));
3692
3693 set_pte_at(vma->vm_mm, vmf->address, vmf->pte, pte);
3694 /*
3695 * Update this to be prepared for following up CoW
3696 * handling
3697 */
3698 vmf->orig_pte = pte;
3699 }
3700
3701 /*
3702 * Userfaultfd write-protect can defer flushes. Ensure the TLB
3703 * is flushed in this case before copying.
3704 */
3705 if (unlikely(userfaultfd_wp(vmf->vma) &&
3706 mm_tlb_flush_pending(vmf->vma->vm_mm)))
3707 flush_tlb_page(vmf->vma, vmf->address);
3708 }
3709
3710 vmf->page = vm_normal_page(vma, vmf->address, vmf->orig_pte);
3711
3712 if (vmf->page)
3713 folio = page_folio(vmf->page);
3714
3715 /*
3716 * Shared mapping: we are guaranteed to have VM_WRITE and
3717 * FAULT_FLAG_WRITE set at this point.
3718 */
3719 if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
3720 /*
3721 * VM_MIXEDMAP !pfn_valid() case, or VM_SOFTDIRTY clear on a
3722 * VM_PFNMAP VMA.
3723 *
3724 * We should not cow pages in a shared writeable mapping.
3725 * Just mark the pages writable and/or call ops->pfn_mkwrite.
3726 */
3727 if (!vmf->page)
3728 return wp_pfn_shared(vmf);
3729 return wp_page_shared(vmf, folio);
3730 }
3731
3732 /*
3733 * Private mapping: create an exclusive anonymous page copy if reuse
3734 * is impossible. We might miss VM_WRITE for FOLL_FORCE handling.
3735 *
3736 * If we encounter a page that is marked exclusive, we must reuse
3737 * the page without further checks.
3738 */
3739 if (folio && folio_test_anon(folio) &&
3740 (PageAnonExclusive(vmf->page) || wp_can_reuse_anon_folio(folio, vma))) {
3741 if (!PageAnonExclusive(vmf->page))
3742 SetPageAnonExclusive(vmf->page);
3743 if (unlikely(unshare)) {
3744 pte_unmap_unlock(vmf->pte, vmf->ptl);
3745 return 0;
3746 }
3747 wp_page_reuse(vmf, folio);
3748 return 0;
3749 }
3750 /*
3751 * Ok, we need to copy. Oh, well..
3752 */
3753 if (folio)
3754 folio_get(folio);
3755
3756 pte_unmap_unlock(vmf->pte, vmf->ptl);
3757#ifdef CONFIG_KSM
3758 if (folio && folio_test_ksm(folio))
3759 count_vm_event(COW_KSM);
3760#endif
3761 return wp_page_copy(vmf);
3762}
3763
3764static void unmap_mapping_range_vma(struct vm_area_struct *vma,
3765 unsigned long start_addr, unsigned long end_addr,
3766 struct zap_details *details)
3767{
3768 zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
3769}
3770
3771static inline void unmap_mapping_range_tree(struct rb_root_cached *root,
3772 pgoff_t first_index,
3773 pgoff_t last_index,
3774 struct zap_details *details)
3775{
3776 struct vm_area_struct *vma;
3777 pgoff_t vba, vea, zba, zea;
3778
3779 vma_interval_tree_foreach(vma, root, first_index, last_index) {
3780 vba = vma->vm_pgoff;
3781 vea = vba + vma_pages(vma) - 1;
3782 zba = max(first_index, vba);
3783 zea = min(last_index, vea);
3784
3785 unmap_mapping_range_vma(vma,
3786 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
3787 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
3788 details);
3789 }
3790}
3791
3792/**
3793 * unmap_mapping_folio() - Unmap single folio from processes.
3794 * @folio: The locked folio to be unmapped.
3795 *
3796 * Unmap this folio from any userspace process which still has it mmaped.
3797 * Typically, for efficiency, the range of nearby pages has already been
3798 * unmapped by unmap_mapping_pages() or unmap_mapping_range(). But once
3799 * truncation or invalidation holds the lock on a folio, it may find that
3800 * the page has been remapped again: and then uses unmap_mapping_folio()
3801 * to unmap it finally.
3802 */
3803void unmap_mapping_folio(struct folio *folio)
3804{
3805 struct address_space *mapping = folio->mapping;
3806 struct zap_details details = { };
3807 pgoff_t first_index;
3808 pgoff_t last_index;
3809
3810 VM_BUG_ON(!folio_test_locked(folio));
3811
3812 first_index = folio->index;
3813 last_index = folio_next_index(folio) - 1;
3814
3815 details.even_cows = false;
3816 details.single_folio = folio;
3817 details.zap_flags = ZAP_FLAG_DROP_MARKER;
3818
3819 i_mmap_lock_read(mapping);
3820 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
3821 unmap_mapping_range_tree(&mapping->i_mmap, first_index,
3822 last_index, &details);
3823 i_mmap_unlock_read(mapping);
3824}
3825
3826/**
3827 * unmap_mapping_pages() - Unmap pages from processes.
3828 * @mapping: The address space containing pages to be unmapped.
3829 * @start: Index of first page to be unmapped.
3830 * @nr: Number of pages to be unmapped. 0 to unmap to end of file.
3831 * @even_cows: Whether to unmap even private COWed pages.
3832 *
3833 * Unmap the pages in this address space from any userspace process which
3834 * has them mmaped. Generally, you want to remove COWed pages as well when
3835 * a file is being truncated, but not when invalidating pages from the page
3836 * cache.
3837 */
3838void unmap_mapping_pages(struct address_space *mapping, pgoff_t start,
3839 pgoff_t nr, bool even_cows)
3840{
3841 struct zap_details details = { };
3842 pgoff_t first_index = start;
3843 pgoff_t last_index = start + nr - 1;
3844
3845 details.even_cows = even_cows;
3846 if (last_index < first_index)
3847 last_index = ULONG_MAX;
3848
3849 i_mmap_lock_read(mapping);
3850 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap.rb_root)))
3851 unmap_mapping_range_tree(&mapping->i_mmap, first_index,
3852 last_index, &details);
3853 i_mmap_unlock_read(mapping);
3854}
3855EXPORT_SYMBOL_GPL(unmap_mapping_pages);
3856
3857/**
3858 * unmap_mapping_range - unmap the portion of all mmaps in the specified
3859 * address_space corresponding to the specified byte range in the underlying
3860 * file.
3861 *
3862 * @mapping: the address space containing mmaps to be unmapped.
3863 * @holebegin: byte in first page to unmap, relative to the start of
3864 * the underlying file. This will be rounded down to a PAGE_SIZE
3865 * boundary. Note that this is different from truncate_pagecache(), which
3866 * must keep the partial page. In contrast, we must get rid of
3867 * partial pages.
3868 * @holelen: size of prospective hole in bytes. This will be rounded
3869 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
3870 * end of the file.
3871 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
3872 * but 0 when invalidating pagecache, don't throw away private data.
3873 */
3874void unmap_mapping_range(struct address_space *mapping,
3875 loff_t const holebegin, loff_t const holelen, int even_cows)
3876{
3877 pgoff_t hba = (pgoff_t)(holebegin) >> PAGE_SHIFT;
3878 pgoff_t hlen = ((pgoff_t)(holelen) + PAGE_SIZE - 1) >> PAGE_SHIFT;
3879
3880 /* Check for overflow. */
3881 if (sizeof(holelen) > sizeof(hlen)) {
3882 long long holeend =
3883 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
3884 if (holeend & ~(long long)ULONG_MAX)
3885 hlen = ULONG_MAX - hba + 1;
3886 }
3887
3888 unmap_mapping_pages(mapping, hba, hlen, even_cows);
3889}
3890EXPORT_SYMBOL(unmap_mapping_range);
3891
3892/*
3893 * Restore a potential device exclusive pte to a working pte entry
3894 */
3895static vm_fault_t remove_device_exclusive_entry(struct vm_fault *vmf)
3896{
3897 struct folio *folio = page_folio(vmf->page);
3898 struct vm_area_struct *vma = vmf->vma;
3899 struct mmu_notifier_range range;
3900 vm_fault_t ret;
3901
3902 /*
3903 * We need a reference to lock the folio because we don't hold
3904 * the PTL so a racing thread can remove the device-exclusive
3905 * entry and unmap it. If the folio is free the entry must
3906 * have been removed already. If it happens to have already
3907 * been re-allocated after being freed all we do is lock and
3908 * unlock it.
3909 */
3910 if (!folio_try_get(folio))
3911 return 0;
3912
3913 ret = folio_lock_or_retry(folio, vmf);
3914 if (ret) {
3915 folio_put(folio);
3916 return ret;
3917 }
3918 mmu_notifier_range_init_owner(&range, MMU_NOTIFY_EXCLUSIVE, 0,
3919 vma->vm_mm, vmf->address & PAGE_MASK,
3920 (vmf->address & PAGE_MASK) + PAGE_SIZE, NULL);
3921 mmu_notifier_invalidate_range_start(&range);
3922
3923 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
3924 &vmf->ptl);
3925 if (likely(vmf->pte && pte_same(ptep_get(vmf->pte), vmf->orig_pte)))
3926 restore_exclusive_pte(vma, vmf->page, vmf->address, vmf->pte);
3927
3928 if (vmf->pte)
3929 pte_unmap_unlock(vmf->pte, vmf->ptl);
3930 folio_unlock(folio);
3931 folio_put(folio);
3932
3933 mmu_notifier_invalidate_range_end(&range);
3934 return 0;
3935}
3936
3937static inline bool should_try_to_free_swap(struct folio *folio,
3938 struct vm_area_struct *vma,
3939 unsigned int fault_flags)
3940{
3941 if (!folio_test_swapcache(folio))
3942 return false;
3943 if (mem_cgroup_swap_full(folio) || (vma->vm_flags & VM_LOCKED) ||
3944 folio_test_mlocked(folio))
3945 return true;
3946 /*
3947 * If we want to map a page that's in the swapcache writable, we
3948 * have to detect via the refcount if we're really the exclusive
3949 * user. Try freeing the swapcache to get rid of the swapcache
3950 * reference only in case it's likely that we'll be the exlusive user.
3951 */
3952 return (fault_flags & FAULT_FLAG_WRITE) && !folio_test_ksm(folio) &&
3953 folio_ref_count(folio) == (1 + folio_nr_pages(folio));
3954}
3955
3956static vm_fault_t pte_marker_clear(struct vm_fault *vmf)
3957{
3958 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd,
3959 vmf->address, &vmf->ptl);
3960 if (!vmf->pte)
3961 return 0;
3962 /*
3963 * Be careful so that we will only recover a special uffd-wp pte into a
3964 * none pte. Otherwise it means the pte could have changed, so retry.
3965 *
3966 * This should also cover the case where e.g. the pte changed
3967 * quickly from a PTE_MARKER_UFFD_WP into PTE_MARKER_POISONED.
3968 * So is_pte_marker() check is not enough to safely drop the pte.
3969 */
3970 if (pte_same(vmf->orig_pte, ptep_get(vmf->pte)))
3971 pte_clear(vmf->vma->vm_mm, vmf->address, vmf->pte);
3972 pte_unmap_unlock(vmf->pte, vmf->ptl);
3973 return 0;
3974}
3975
3976static vm_fault_t do_pte_missing(struct vm_fault *vmf)
3977{
3978 if (vma_is_anonymous(vmf->vma))
3979 return do_anonymous_page(vmf);
3980 else
3981 return do_fault(vmf);
3982}
3983
3984/*
3985 * This is actually a page-missing access, but with uffd-wp special pte
3986 * installed. It means this pte was wr-protected before being unmapped.
3987 */
3988static vm_fault_t pte_marker_handle_uffd_wp(struct vm_fault *vmf)
3989{
3990 /*
3991 * Just in case there're leftover special ptes even after the region
3992 * got unregistered - we can simply clear them.
3993 */
3994 if (unlikely(!userfaultfd_wp(vmf->vma)))
3995 return pte_marker_clear(vmf);
3996
3997 return do_pte_missing(vmf);
3998}
3999
4000static vm_fault_t handle_pte_marker(struct vm_fault *vmf)
4001{
4002 swp_entry_t entry = pte_to_swp_entry(vmf->orig_pte);
4003 unsigned long marker = pte_marker_get(entry);
4004
4005 /*
4006 * PTE markers should never be empty. If anything weird happened,
4007 * the best thing to do is to kill the process along with its mm.
4008 */
4009 if (WARN_ON_ONCE(!marker))
4010 return VM_FAULT_SIGBUS;
4011
4012 /* Higher priority than uffd-wp when data corrupted */
4013 if (marker & PTE_MARKER_POISONED)
4014 return VM_FAULT_HWPOISON;
4015
4016 /* Hitting a guard page is always a fatal condition. */
4017 if (marker & PTE_MARKER_GUARD)
4018 return VM_FAULT_SIGSEGV;
4019
4020 if (pte_marker_entry_uffd_wp(entry))
4021 return pte_marker_handle_uffd_wp(vmf);
4022
4023 /* This is an unknown pte marker */
4024 return VM_FAULT_SIGBUS;
4025}
4026
4027static struct folio *__alloc_swap_folio(struct vm_fault *vmf)
4028{
4029 struct vm_area_struct *vma = vmf->vma;
4030 struct folio *folio;
4031 swp_entry_t entry;
4032
4033 folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vmf->address);
4034 if (!folio)
4035 return NULL;
4036
4037 entry = pte_to_swp_entry(vmf->orig_pte);
4038 if (mem_cgroup_swapin_charge_folio(folio, vma->vm_mm,
4039 GFP_KERNEL, entry)) {
4040 folio_put(folio);
4041 return NULL;
4042 }
4043
4044 return folio;
4045}
4046
4047#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4048static inline int non_swapcache_batch(swp_entry_t entry, int max_nr)
4049{
4050 struct swap_info_struct *si = swp_swap_info(entry);
4051 pgoff_t offset = swp_offset(entry);
4052 int i;
4053
4054 /*
4055 * While allocating a large folio and doing swap_read_folio, which is
4056 * the case the being faulted pte doesn't have swapcache. We need to
4057 * ensure all PTEs have no cache as well, otherwise, we might go to
4058 * swap devices while the content is in swapcache.
4059 */
4060 for (i = 0; i < max_nr; i++) {
4061 if ((si->swap_map[offset + i] & SWAP_HAS_CACHE))
4062 return i;
4063 }
4064
4065 return i;
4066}
4067
4068/*
4069 * Check if the PTEs within a range are contiguous swap entries
4070 * and have consistent swapcache, zeromap.
4071 */
4072static bool can_swapin_thp(struct vm_fault *vmf, pte_t *ptep, int nr_pages)
4073{
4074 unsigned long addr;
4075 swp_entry_t entry;
4076 int idx;
4077 pte_t pte;
4078
4079 addr = ALIGN_DOWN(vmf->address, nr_pages * PAGE_SIZE);
4080 idx = (vmf->address - addr) / PAGE_SIZE;
4081 pte = ptep_get(ptep);
4082
4083 if (!pte_same(pte, pte_move_swp_offset(vmf->orig_pte, -idx)))
4084 return false;
4085 entry = pte_to_swp_entry(pte);
4086 if (swap_pte_batch(ptep, nr_pages, pte) != nr_pages)
4087 return false;
4088
4089 /*
4090 * swap_read_folio() can't handle the case a large folio is hybridly
4091 * from different backends. And they are likely corner cases. Similar
4092 * things might be added once zswap support large folios.
4093 */
4094 if (unlikely(swap_zeromap_batch(entry, nr_pages, NULL) != nr_pages))
4095 return false;
4096 if (unlikely(non_swapcache_batch(entry, nr_pages) != nr_pages))
4097 return false;
4098
4099 return true;
4100}
4101
4102static inline unsigned long thp_swap_suitable_orders(pgoff_t swp_offset,
4103 unsigned long addr,
4104 unsigned long orders)
4105{
4106 int order, nr;
4107
4108 order = highest_order(orders);
4109
4110 /*
4111 * To swap in a THP with nr pages, we require that its first swap_offset
4112 * is aligned with that number, as it was when the THP was swapped out.
4113 * This helps filter out most invalid entries.
4114 */
4115 while (orders) {
4116 nr = 1 << order;
4117 if ((addr >> PAGE_SHIFT) % nr == swp_offset % nr)
4118 break;
4119 order = next_order(&orders, order);
4120 }
4121
4122 return orders;
4123}
4124
4125static struct folio *alloc_swap_folio(struct vm_fault *vmf)
4126{
4127 struct vm_area_struct *vma = vmf->vma;
4128 unsigned long orders;
4129 struct folio *folio;
4130 unsigned long addr;
4131 swp_entry_t entry;
4132 spinlock_t *ptl;
4133 pte_t *pte;
4134 gfp_t gfp;
4135 int order;
4136
4137 /*
4138 * If uffd is active for the vma we need per-page fault fidelity to
4139 * maintain the uffd semantics.
4140 */
4141 if (unlikely(userfaultfd_armed(vma)))
4142 goto fallback;
4143
4144 /*
4145 * A large swapped out folio could be partially or fully in zswap. We
4146 * lack handling for such cases, so fallback to swapping in order-0
4147 * folio.
4148 */
4149 if (!zswap_never_enabled())
4150 goto fallback;
4151
4152 entry = pte_to_swp_entry(vmf->orig_pte);
4153 /*
4154 * Get a list of all the (large) orders below PMD_ORDER that are enabled
4155 * and suitable for swapping THP.
4156 */
4157 orders = thp_vma_allowable_orders(vma, vma->vm_flags,
4158 TVA_IN_PF | TVA_ENFORCE_SYSFS, BIT(PMD_ORDER) - 1);
4159 orders = thp_vma_suitable_orders(vma, vmf->address, orders);
4160 orders = thp_swap_suitable_orders(swp_offset(entry),
4161 vmf->address, orders);
4162
4163 if (!orders)
4164 goto fallback;
4165
4166 pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd,
4167 vmf->address & PMD_MASK, &ptl);
4168 if (unlikely(!pte))
4169 goto fallback;
4170
4171 /*
4172 * For do_swap_page, find the highest order where the aligned range is
4173 * completely swap entries with contiguous swap offsets.
4174 */
4175 order = highest_order(orders);
4176 while (orders) {
4177 addr = ALIGN_DOWN(vmf->address, PAGE_SIZE << order);
4178 if (can_swapin_thp(vmf, pte + pte_index(addr), 1 << order))
4179 break;
4180 order = next_order(&orders, order);
4181 }
4182
4183 pte_unmap_unlock(pte, ptl);
4184
4185 /* Try allocating the highest of the remaining orders. */
4186 gfp = vma_thp_gfp_mask(vma);
4187 while (orders) {
4188 addr = ALIGN_DOWN(vmf->address, PAGE_SIZE << order);
4189 folio = vma_alloc_folio(gfp, order, vma, addr);
4190 if (folio) {
4191 if (!mem_cgroup_swapin_charge_folio(folio, vma->vm_mm,
4192 gfp, entry))
4193 return folio;
4194 folio_put(folio);
4195 }
4196 order = next_order(&orders, order);
4197 }
4198
4199fallback:
4200 return __alloc_swap_folio(vmf);
4201}
4202#else /* !CONFIG_TRANSPARENT_HUGEPAGE */
4203static struct folio *alloc_swap_folio(struct vm_fault *vmf)
4204{
4205 return __alloc_swap_folio(vmf);
4206}
4207#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
4208
4209static DECLARE_WAIT_QUEUE_HEAD(swapcache_wq);
4210
4211/*
4212 * We enter with non-exclusive mmap_lock (to exclude vma changes,
4213 * but allow concurrent faults), and pte mapped but not yet locked.
4214 * We return with pte unmapped and unlocked.
4215 *
4216 * We return with the mmap_lock locked or unlocked in the same cases
4217 * as does filemap_fault().
4218 */
4219vm_fault_t do_swap_page(struct vm_fault *vmf)
4220{
4221 struct vm_area_struct *vma = vmf->vma;
4222 struct folio *swapcache, *folio = NULL;
4223 DECLARE_WAITQUEUE(wait, current);
4224 struct page *page;
4225 struct swap_info_struct *si = NULL;
4226 rmap_t rmap_flags = RMAP_NONE;
4227 bool need_clear_cache = false;
4228 bool exclusive = false;
4229 swp_entry_t entry;
4230 pte_t pte;
4231 vm_fault_t ret = 0;
4232 void *shadow = NULL;
4233 int nr_pages;
4234 unsigned long page_idx;
4235 unsigned long address;
4236 pte_t *ptep;
4237
4238 if (!pte_unmap_same(vmf))
4239 goto out;
4240
4241 entry = pte_to_swp_entry(vmf->orig_pte);
4242 if (unlikely(non_swap_entry(entry))) {
4243 if (is_migration_entry(entry)) {
4244 migration_entry_wait(vma->vm_mm, vmf->pmd,
4245 vmf->address);
4246 } else if (is_device_exclusive_entry(entry)) {
4247 vmf->page = pfn_swap_entry_to_page(entry);
4248 ret = remove_device_exclusive_entry(vmf);
4249 } else if (is_device_private_entry(entry)) {
4250 if (vmf->flags & FAULT_FLAG_VMA_LOCK) {
4251 /*
4252 * migrate_to_ram is not yet ready to operate
4253 * under VMA lock.
4254 */
4255 vma_end_read(vma);
4256 ret = VM_FAULT_RETRY;
4257 goto out;
4258 }
4259
4260 vmf->page = pfn_swap_entry_to_page(entry);
4261 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4262 vmf->address, &vmf->ptl);
4263 if (unlikely(!vmf->pte ||
4264 !pte_same(ptep_get(vmf->pte),
4265 vmf->orig_pte)))
4266 goto unlock;
4267
4268 /*
4269 * Get a page reference while we know the page can't be
4270 * freed.
4271 */
4272 get_page(vmf->page);
4273 pte_unmap_unlock(vmf->pte, vmf->ptl);
4274 ret = vmf->page->pgmap->ops->migrate_to_ram(vmf);
4275 put_page(vmf->page);
4276 } else if (is_hwpoison_entry(entry)) {
4277 ret = VM_FAULT_HWPOISON;
4278 } else if (is_pte_marker_entry(entry)) {
4279 ret = handle_pte_marker(vmf);
4280 } else {
4281 print_bad_pte(vma, vmf->address, vmf->orig_pte, NULL);
4282 ret = VM_FAULT_SIGBUS;
4283 }
4284 goto out;
4285 }
4286
4287 /* Prevent swapoff from happening to us. */
4288 si = get_swap_device(entry);
4289 if (unlikely(!si))
4290 goto out;
4291
4292 folio = swap_cache_get_folio(entry, vma, vmf->address);
4293 if (folio)
4294 page = folio_file_page(folio, swp_offset(entry));
4295 swapcache = folio;
4296
4297 if (!folio) {
4298 if (data_race(si->flags & SWP_SYNCHRONOUS_IO) &&
4299 __swap_count(entry) == 1) {
4300 /* skip swapcache */
4301 folio = alloc_swap_folio(vmf);
4302 if (folio) {
4303 __folio_set_locked(folio);
4304 __folio_set_swapbacked(folio);
4305
4306 nr_pages = folio_nr_pages(folio);
4307 if (folio_test_large(folio))
4308 entry.val = ALIGN_DOWN(entry.val, nr_pages);
4309 /*
4310 * Prevent parallel swapin from proceeding with
4311 * the cache flag. Otherwise, another thread
4312 * may finish swapin first, free the entry, and
4313 * swapout reusing the same entry. It's
4314 * undetectable as pte_same() returns true due
4315 * to entry reuse.
4316 */
4317 if (swapcache_prepare(entry, nr_pages)) {
4318 /*
4319 * Relax a bit to prevent rapid
4320 * repeated page faults.
4321 */
4322 add_wait_queue(&swapcache_wq, &wait);
4323 schedule_timeout_uninterruptible(1);
4324 remove_wait_queue(&swapcache_wq, &wait);
4325 goto out_page;
4326 }
4327 need_clear_cache = true;
4328
4329 mem_cgroup_swapin_uncharge_swap(entry, nr_pages);
4330
4331 shadow = get_shadow_from_swap_cache(entry);
4332 if (shadow)
4333 workingset_refault(folio, shadow);
4334
4335 folio_add_lru(folio);
4336
4337 /* To provide entry to swap_read_folio() */
4338 folio->swap = entry;
4339 swap_read_folio(folio, NULL);
4340 folio->private = NULL;
4341 }
4342 } else {
4343 folio = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
4344 vmf);
4345 swapcache = folio;
4346 }
4347
4348 if (!folio) {
4349 /*
4350 * Back out if somebody else faulted in this pte
4351 * while we released the pte lock.
4352 */
4353 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4354 vmf->address, &vmf->ptl);
4355 if (likely(vmf->pte &&
4356 pte_same(ptep_get(vmf->pte), vmf->orig_pte)))
4357 ret = VM_FAULT_OOM;
4358 goto unlock;
4359 }
4360
4361 /* Had to read the page from swap area: Major fault */
4362 ret = VM_FAULT_MAJOR;
4363 count_vm_event(PGMAJFAULT);
4364 count_memcg_event_mm(vma->vm_mm, PGMAJFAULT);
4365 page = folio_file_page(folio, swp_offset(entry));
4366 } else if (PageHWPoison(page)) {
4367 /*
4368 * hwpoisoned dirty swapcache pages are kept for killing
4369 * owner processes (which may be unknown at hwpoison time)
4370 */
4371 ret = VM_FAULT_HWPOISON;
4372 goto out_release;
4373 }
4374
4375 ret |= folio_lock_or_retry(folio, vmf);
4376 if (ret & VM_FAULT_RETRY)
4377 goto out_release;
4378
4379 if (swapcache) {
4380 /*
4381 * Make sure folio_free_swap() or swapoff did not release the
4382 * swapcache from under us. The page pin, and pte_same test
4383 * below, are not enough to exclude that. Even if it is still
4384 * swapcache, we need to check that the page's swap has not
4385 * changed.
4386 */
4387 if (unlikely(!folio_test_swapcache(folio) ||
4388 page_swap_entry(page).val != entry.val))
4389 goto out_page;
4390
4391 /*
4392 * KSM sometimes has to copy on read faults, for example, if
4393 * page->index of !PageKSM() pages would be nonlinear inside the
4394 * anon VMA -- PageKSM() is lost on actual swapout.
4395 */
4396 folio = ksm_might_need_to_copy(folio, vma, vmf->address);
4397 if (unlikely(!folio)) {
4398 ret = VM_FAULT_OOM;
4399 folio = swapcache;
4400 goto out_page;
4401 } else if (unlikely(folio == ERR_PTR(-EHWPOISON))) {
4402 ret = VM_FAULT_HWPOISON;
4403 folio = swapcache;
4404 goto out_page;
4405 }
4406 if (folio != swapcache)
4407 page = folio_page(folio, 0);
4408
4409 /*
4410 * If we want to map a page that's in the swapcache writable, we
4411 * have to detect via the refcount if we're really the exclusive
4412 * owner. Try removing the extra reference from the local LRU
4413 * caches if required.
4414 */
4415 if ((vmf->flags & FAULT_FLAG_WRITE) && folio == swapcache &&
4416 !folio_test_ksm(folio) && !folio_test_lru(folio))
4417 lru_add_drain();
4418 }
4419
4420 folio_throttle_swaprate(folio, GFP_KERNEL);
4421
4422 /*
4423 * Back out if somebody else already faulted in this pte.
4424 */
4425 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, vmf->address,
4426 &vmf->ptl);
4427 if (unlikely(!vmf->pte || !pte_same(ptep_get(vmf->pte), vmf->orig_pte)))
4428 goto out_nomap;
4429
4430 if (unlikely(!folio_test_uptodate(folio))) {
4431 ret = VM_FAULT_SIGBUS;
4432 goto out_nomap;
4433 }
4434
4435 /* allocated large folios for SWP_SYNCHRONOUS_IO */
4436 if (folio_test_large(folio) && !folio_test_swapcache(folio)) {
4437 unsigned long nr = folio_nr_pages(folio);
4438 unsigned long folio_start = ALIGN_DOWN(vmf->address, nr * PAGE_SIZE);
4439 unsigned long idx = (vmf->address - folio_start) / PAGE_SIZE;
4440 pte_t *folio_ptep = vmf->pte - idx;
4441 pte_t folio_pte = ptep_get(folio_ptep);
4442
4443 if (!pte_same(folio_pte, pte_move_swp_offset(vmf->orig_pte, -idx)) ||
4444 swap_pte_batch(folio_ptep, nr, folio_pte) != nr)
4445 goto out_nomap;
4446
4447 page_idx = idx;
4448 address = folio_start;
4449 ptep = folio_ptep;
4450 goto check_folio;
4451 }
4452
4453 nr_pages = 1;
4454 page_idx = 0;
4455 address = vmf->address;
4456 ptep = vmf->pte;
4457 if (folio_test_large(folio) && folio_test_swapcache(folio)) {
4458 int nr = folio_nr_pages(folio);
4459 unsigned long idx = folio_page_idx(folio, page);
4460 unsigned long folio_start = address - idx * PAGE_SIZE;
4461 unsigned long folio_end = folio_start + nr * PAGE_SIZE;
4462 pte_t *folio_ptep;
4463 pte_t folio_pte;
4464
4465 if (unlikely(folio_start < max(address & PMD_MASK, vma->vm_start)))
4466 goto check_folio;
4467 if (unlikely(folio_end > pmd_addr_end(address, vma->vm_end)))
4468 goto check_folio;
4469
4470 folio_ptep = vmf->pte - idx;
4471 folio_pte = ptep_get(folio_ptep);
4472 if (!pte_same(folio_pte, pte_move_swp_offset(vmf->orig_pte, -idx)) ||
4473 swap_pte_batch(folio_ptep, nr, folio_pte) != nr)
4474 goto check_folio;
4475
4476 page_idx = idx;
4477 address = folio_start;
4478 ptep = folio_ptep;
4479 nr_pages = nr;
4480 entry = folio->swap;
4481 page = &folio->page;
4482 }
4483
4484check_folio:
4485 /*
4486 * PG_anon_exclusive reuses PG_mappedtodisk for anon pages. A swap pte
4487 * must never point at an anonymous page in the swapcache that is
4488 * PG_anon_exclusive. Sanity check that this holds and especially, that
4489 * no filesystem set PG_mappedtodisk on a page in the swapcache. Sanity
4490 * check after taking the PT lock and making sure that nobody
4491 * concurrently faulted in this page and set PG_anon_exclusive.
4492 */
4493 BUG_ON(!folio_test_anon(folio) && folio_test_mappedtodisk(folio));
4494 BUG_ON(folio_test_anon(folio) && PageAnonExclusive(page));
4495
4496 /*
4497 * Check under PT lock (to protect against concurrent fork() sharing
4498 * the swap entry concurrently) for certainly exclusive pages.
4499 */
4500 if (!folio_test_ksm(folio)) {
4501 exclusive = pte_swp_exclusive(vmf->orig_pte);
4502 if (folio != swapcache) {
4503 /*
4504 * We have a fresh page that is not exposed to the
4505 * swapcache -> certainly exclusive.
4506 */
4507 exclusive = true;
4508 } else if (exclusive && folio_test_writeback(folio) &&
4509 data_race(si->flags & SWP_STABLE_WRITES)) {
4510 /*
4511 * This is tricky: not all swap backends support
4512 * concurrent page modifications while under writeback.
4513 *
4514 * So if we stumble over such a page in the swapcache
4515 * we must not set the page exclusive, otherwise we can
4516 * map it writable without further checks and modify it
4517 * while still under writeback.
4518 *
4519 * For these problematic swap backends, simply drop the
4520 * exclusive marker: this is perfectly fine as we start
4521 * writeback only if we fully unmapped the page and
4522 * there are no unexpected references on the page after
4523 * unmapping succeeded. After fully unmapped, no
4524 * further GUP references (FOLL_GET and FOLL_PIN) can
4525 * appear, so dropping the exclusive marker and mapping
4526 * it only R/O is fine.
4527 */
4528 exclusive = false;
4529 }
4530 }
4531
4532 /*
4533 * Some architectures may have to restore extra metadata to the page
4534 * when reading from swap. This metadata may be indexed by swap entry
4535 * so this must be called before swap_free().
4536 */
4537 arch_swap_restore(folio_swap(entry, folio), folio);
4538
4539 /*
4540 * Remove the swap entry and conditionally try to free up the swapcache.
4541 * We're already holding a reference on the page but haven't mapped it
4542 * yet.
4543 */
4544 swap_free_nr(entry, nr_pages);
4545 if (should_try_to_free_swap(folio, vma, vmf->flags))
4546 folio_free_swap(folio);
4547
4548 add_mm_counter(vma->vm_mm, MM_ANONPAGES, nr_pages);
4549 add_mm_counter(vma->vm_mm, MM_SWAPENTS, -nr_pages);
4550 pte = mk_pte(page, vma->vm_page_prot);
4551 if (pte_swp_soft_dirty(vmf->orig_pte))
4552 pte = pte_mksoft_dirty(pte);
4553 if (pte_swp_uffd_wp(vmf->orig_pte))
4554 pte = pte_mkuffd_wp(pte);
4555
4556 /*
4557 * Same logic as in do_wp_page(); however, optimize for pages that are
4558 * certainly not shared either because we just allocated them without
4559 * exposing them to the swapcache or because the swap entry indicates
4560 * exclusivity.
4561 */
4562 if (!folio_test_ksm(folio) &&
4563 (exclusive || folio_ref_count(folio) == 1)) {
4564 if ((vma->vm_flags & VM_WRITE) && !userfaultfd_pte_wp(vma, pte) &&
4565 !pte_needs_soft_dirty_wp(vma, pte)) {
4566 pte = pte_mkwrite(pte, vma);
4567 if (vmf->flags & FAULT_FLAG_WRITE) {
4568 pte = pte_mkdirty(pte);
4569 vmf->flags &= ~FAULT_FLAG_WRITE;
4570 }
4571 }
4572 rmap_flags |= RMAP_EXCLUSIVE;
4573 }
4574 folio_ref_add(folio, nr_pages - 1);
4575 flush_icache_pages(vma, page, nr_pages);
4576 vmf->orig_pte = pte_advance_pfn(pte, page_idx);
4577
4578 /* ksm created a completely new copy */
4579 if (unlikely(folio != swapcache && swapcache)) {
4580 folio_add_new_anon_rmap(folio, vma, address, RMAP_EXCLUSIVE);
4581 folio_add_lru_vma(folio, vma);
4582 } else if (!folio_test_anon(folio)) {
4583 /*
4584 * We currently only expect small !anon folios which are either
4585 * fully exclusive or fully shared, or new allocated large
4586 * folios which are fully exclusive. If we ever get large
4587 * folios within swapcache here, we have to be careful.
4588 */
4589 VM_WARN_ON_ONCE(folio_test_large(folio) && folio_test_swapcache(folio));
4590 VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio);
4591 folio_add_new_anon_rmap(folio, vma, address, rmap_flags);
4592 } else {
4593 folio_add_anon_rmap_ptes(folio, page, nr_pages, vma, address,
4594 rmap_flags);
4595 }
4596
4597 VM_BUG_ON(!folio_test_anon(folio) ||
4598 (pte_write(pte) && !PageAnonExclusive(page)));
4599 set_ptes(vma->vm_mm, address, ptep, pte, nr_pages);
4600 arch_do_swap_page_nr(vma->vm_mm, vma, address,
4601 pte, pte, nr_pages);
4602
4603 folio_unlock(folio);
4604 if (folio != swapcache && swapcache) {
4605 /*
4606 * Hold the lock to avoid the swap entry to be reused
4607 * until we take the PT lock for the pte_same() check
4608 * (to avoid false positives from pte_same). For
4609 * further safety release the lock after the swap_free
4610 * so that the swap count won't change under a
4611 * parallel locked swapcache.
4612 */
4613 folio_unlock(swapcache);
4614 folio_put(swapcache);
4615 }
4616
4617 if (vmf->flags & FAULT_FLAG_WRITE) {
4618 ret |= do_wp_page(vmf);
4619 if (ret & VM_FAULT_ERROR)
4620 ret &= VM_FAULT_ERROR;
4621 goto out;
4622 }
4623
4624 /* No need to invalidate - it was non-present before */
4625 update_mmu_cache_range(vmf, vma, address, ptep, nr_pages);
4626unlock:
4627 if (vmf->pte)
4628 pte_unmap_unlock(vmf->pte, vmf->ptl);
4629out:
4630 /* Clear the swap cache pin for direct swapin after PTL unlock */
4631 if (need_clear_cache) {
4632 swapcache_clear(si, entry, nr_pages);
4633 if (waitqueue_active(&swapcache_wq))
4634 wake_up(&swapcache_wq);
4635 }
4636 if (si)
4637 put_swap_device(si);
4638 return ret;
4639out_nomap:
4640 if (vmf->pte)
4641 pte_unmap_unlock(vmf->pte, vmf->ptl);
4642out_page:
4643 folio_unlock(folio);
4644out_release:
4645 folio_put(folio);
4646 if (folio != swapcache && swapcache) {
4647 folio_unlock(swapcache);
4648 folio_put(swapcache);
4649 }
4650 if (need_clear_cache) {
4651 swapcache_clear(si, entry, nr_pages);
4652 if (waitqueue_active(&swapcache_wq))
4653 wake_up(&swapcache_wq);
4654 }
4655 if (si)
4656 put_swap_device(si);
4657 return ret;
4658}
4659
4660static bool pte_range_none(pte_t *pte, int nr_pages)
4661{
4662 int i;
4663
4664 for (i = 0; i < nr_pages; i++) {
4665 if (!pte_none(ptep_get_lockless(pte + i)))
4666 return false;
4667 }
4668
4669 return true;
4670}
4671
4672static struct folio *alloc_anon_folio(struct vm_fault *vmf)
4673{
4674 struct vm_area_struct *vma = vmf->vma;
4675#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4676 unsigned long orders;
4677 struct folio *folio;
4678 unsigned long addr;
4679 pte_t *pte;
4680 gfp_t gfp;
4681 int order;
4682
4683 /*
4684 * If uffd is active for the vma we need per-page fault fidelity to
4685 * maintain the uffd semantics.
4686 */
4687 if (unlikely(userfaultfd_armed(vma)))
4688 goto fallback;
4689
4690 /*
4691 * Get a list of all the (large) orders below PMD_ORDER that are enabled
4692 * for this vma. Then filter out the orders that can't be allocated over
4693 * the faulting address and still be fully contained in the vma.
4694 */
4695 orders = thp_vma_allowable_orders(vma, vma->vm_flags,
4696 TVA_IN_PF | TVA_ENFORCE_SYSFS, BIT(PMD_ORDER) - 1);
4697 orders = thp_vma_suitable_orders(vma, vmf->address, orders);
4698
4699 if (!orders)
4700 goto fallback;
4701
4702 pte = pte_offset_map(vmf->pmd, vmf->address & PMD_MASK);
4703 if (!pte)
4704 return ERR_PTR(-EAGAIN);
4705
4706 /*
4707 * Find the highest order where the aligned range is completely
4708 * pte_none(). Note that all remaining orders will be completely
4709 * pte_none().
4710 */
4711 order = highest_order(orders);
4712 while (orders) {
4713 addr = ALIGN_DOWN(vmf->address, PAGE_SIZE << order);
4714 if (pte_range_none(pte + pte_index(addr), 1 << order))
4715 break;
4716 order = next_order(&orders, order);
4717 }
4718
4719 pte_unmap(pte);
4720
4721 if (!orders)
4722 goto fallback;
4723
4724 /* Try allocating the highest of the remaining orders. */
4725 gfp = vma_thp_gfp_mask(vma);
4726 while (orders) {
4727 addr = ALIGN_DOWN(vmf->address, PAGE_SIZE << order);
4728 folio = vma_alloc_folio(gfp, order, vma, addr);
4729 if (folio) {
4730 if (mem_cgroup_charge(folio, vma->vm_mm, gfp)) {
4731 count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK_CHARGE);
4732 folio_put(folio);
4733 goto next;
4734 }
4735 folio_throttle_swaprate(folio, gfp);
4736 /*
4737 * When a folio is not zeroed during allocation
4738 * (__GFP_ZERO not used) or user folios require special
4739 * handling, folio_zero_user() is used to make sure
4740 * that the page corresponding to the faulting address
4741 * will be hot in the cache after zeroing.
4742 */
4743 if (user_alloc_needs_zeroing())
4744 folio_zero_user(folio, vmf->address);
4745 return folio;
4746 }
4747next:
4748 count_mthp_stat(order, MTHP_STAT_ANON_FAULT_FALLBACK);
4749 order = next_order(&orders, order);
4750 }
4751
4752fallback:
4753#endif
4754 return folio_prealloc(vma->vm_mm, vma, vmf->address, true);
4755}
4756
4757/*
4758 * We enter with non-exclusive mmap_lock (to exclude vma changes,
4759 * but allow concurrent faults), and pte mapped but not yet locked.
4760 * We return with mmap_lock still held, but pte unmapped and unlocked.
4761 */
4762static vm_fault_t do_anonymous_page(struct vm_fault *vmf)
4763{
4764 struct vm_area_struct *vma = vmf->vma;
4765 unsigned long addr = vmf->address;
4766 struct folio *folio;
4767 vm_fault_t ret = 0;
4768 int nr_pages = 1;
4769 pte_t entry;
4770
4771 /* File mapping without ->vm_ops ? */
4772 if (vma->vm_flags & VM_SHARED)
4773 return VM_FAULT_SIGBUS;
4774
4775 /*
4776 * Use pte_alloc() instead of pte_alloc_map(), so that OOM can
4777 * be distinguished from a transient failure of pte_offset_map().
4778 */
4779 if (pte_alloc(vma->vm_mm, vmf->pmd))
4780 return VM_FAULT_OOM;
4781
4782 /* Use the zero-page for reads */
4783 if (!(vmf->flags & FAULT_FLAG_WRITE) &&
4784 !mm_forbids_zeropage(vma->vm_mm)) {
4785 entry = pte_mkspecial(pfn_pte(my_zero_pfn(vmf->address),
4786 vma->vm_page_prot));
4787 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
4788 vmf->address, &vmf->ptl);
4789 if (!vmf->pte)
4790 goto unlock;
4791 if (vmf_pte_changed(vmf)) {
4792 update_mmu_tlb(vma, vmf->address, vmf->pte);
4793 goto unlock;
4794 }
4795 ret = check_stable_address_space(vma->vm_mm);
4796 if (ret)
4797 goto unlock;
4798 /* Deliver the page fault to userland, check inside PT lock */
4799 if (userfaultfd_missing(vma)) {
4800 pte_unmap_unlock(vmf->pte, vmf->ptl);
4801 return handle_userfault(vmf, VM_UFFD_MISSING);
4802 }
4803 goto setpte;
4804 }
4805
4806 /* Allocate our own private page. */
4807 ret = vmf_anon_prepare(vmf);
4808 if (ret)
4809 return ret;
4810 /* Returns NULL on OOM or ERR_PTR(-EAGAIN) if we must retry the fault */
4811 folio = alloc_anon_folio(vmf);
4812 if (IS_ERR(folio))
4813 return 0;
4814 if (!folio)
4815 goto oom;
4816
4817 nr_pages = folio_nr_pages(folio);
4818 addr = ALIGN_DOWN(vmf->address, nr_pages * PAGE_SIZE);
4819
4820 /*
4821 * The memory barrier inside __folio_mark_uptodate makes sure that
4822 * preceding stores to the page contents become visible before
4823 * the set_pte_at() write.
4824 */
4825 __folio_mark_uptodate(folio);
4826
4827 entry = mk_pte(&folio->page, vma->vm_page_prot);
4828 entry = pte_sw_mkyoung(entry);
4829 if (vma->vm_flags & VM_WRITE)
4830 entry = pte_mkwrite(pte_mkdirty(entry), vma);
4831
4832 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, addr, &vmf->ptl);
4833 if (!vmf->pte)
4834 goto release;
4835 if (nr_pages == 1 && vmf_pte_changed(vmf)) {
4836 update_mmu_tlb(vma, addr, vmf->pte);
4837 goto release;
4838 } else if (nr_pages > 1 && !pte_range_none(vmf->pte, nr_pages)) {
4839 update_mmu_tlb_range(vma, addr, vmf->pte, nr_pages);
4840 goto release;
4841 }
4842
4843 ret = check_stable_address_space(vma->vm_mm);
4844 if (ret)
4845 goto release;
4846
4847 /* Deliver the page fault to userland, check inside PT lock */
4848 if (userfaultfd_missing(vma)) {
4849 pte_unmap_unlock(vmf->pte, vmf->ptl);
4850 folio_put(folio);
4851 return handle_userfault(vmf, VM_UFFD_MISSING);
4852 }
4853
4854 folio_ref_add(folio, nr_pages - 1);
4855 add_mm_counter(vma->vm_mm, MM_ANONPAGES, nr_pages);
4856 count_mthp_stat(folio_order(folio), MTHP_STAT_ANON_FAULT_ALLOC);
4857 folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE);
4858 folio_add_lru_vma(folio, vma);
4859setpte:
4860 if (vmf_orig_pte_uffd_wp(vmf))
4861 entry = pte_mkuffd_wp(entry);
4862 set_ptes(vma->vm_mm, addr, vmf->pte, entry, nr_pages);
4863
4864 /* No need to invalidate - it was non-present before */
4865 update_mmu_cache_range(vmf, vma, addr, vmf->pte, nr_pages);
4866unlock:
4867 if (vmf->pte)
4868 pte_unmap_unlock(vmf->pte, vmf->ptl);
4869 return ret;
4870release:
4871 folio_put(folio);
4872 goto unlock;
4873oom:
4874 return VM_FAULT_OOM;
4875}
4876
4877/*
4878 * The mmap_lock must have been held on entry, and may have been
4879 * released depending on flags and vma->vm_ops->fault() return value.
4880 * See filemap_fault() and __lock_page_retry().
4881 */
4882static vm_fault_t __do_fault(struct vm_fault *vmf)
4883{
4884 struct vm_area_struct *vma = vmf->vma;
4885 struct folio *folio;
4886 vm_fault_t ret;
4887
4888 /*
4889 * Preallocate pte before we take page_lock because this might lead to
4890 * deadlocks for memcg reclaim which waits for pages under writeback:
4891 * lock_page(A)
4892 * SetPageWriteback(A)
4893 * unlock_page(A)
4894 * lock_page(B)
4895 * lock_page(B)
4896 * pte_alloc_one
4897 * shrink_folio_list
4898 * wait_on_page_writeback(A)
4899 * SetPageWriteback(B)
4900 * unlock_page(B)
4901 * # flush A, B to clear the writeback
4902 */
4903 if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) {
4904 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
4905 if (!vmf->prealloc_pte)
4906 return VM_FAULT_OOM;
4907 }
4908
4909 ret = vma->vm_ops->fault(vmf);
4910 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY |
4911 VM_FAULT_DONE_COW)))
4912 return ret;
4913
4914 folio = page_folio(vmf->page);
4915 if (unlikely(PageHWPoison(vmf->page))) {
4916 vm_fault_t poisonret = VM_FAULT_HWPOISON;
4917 if (ret & VM_FAULT_LOCKED) {
4918 if (page_mapped(vmf->page))
4919 unmap_mapping_folio(folio);
4920 /* Retry if a clean folio was removed from the cache. */
4921 if (mapping_evict_folio(folio->mapping, folio))
4922 poisonret = VM_FAULT_NOPAGE;
4923 folio_unlock(folio);
4924 }
4925 folio_put(folio);
4926 vmf->page = NULL;
4927 return poisonret;
4928 }
4929
4930 if (unlikely(!(ret & VM_FAULT_LOCKED)))
4931 folio_lock(folio);
4932 else
4933 VM_BUG_ON_PAGE(!folio_test_locked(folio), vmf->page);
4934
4935 return ret;
4936}
4937
4938#ifdef CONFIG_TRANSPARENT_HUGEPAGE
4939static void deposit_prealloc_pte(struct vm_fault *vmf)
4940{
4941 struct vm_area_struct *vma = vmf->vma;
4942
4943 pgtable_trans_huge_deposit(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
4944 /*
4945 * We are going to consume the prealloc table,
4946 * count that as nr_ptes.
4947 */
4948 mm_inc_nr_ptes(vma->vm_mm);
4949 vmf->prealloc_pte = NULL;
4950}
4951
4952vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
4953{
4954 struct folio *folio = page_folio(page);
4955 struct vm_area_struct *vma = vmf->vma;
4956 bool write = vmf->flags & FAULT_FLAG_WRITE;
4957 unsigned long haddr = vmf->address & HPAGE_PMD_MASK;
4958 pmd_t entry;
4959 vm_fault_t ret = VM_FAULT_FALLBACK;
4960
4961 /*
4962 * It is too late to allocate a small folio, we already have a large
4963 * folio in the pagecache: especially s390 KVM cannot tolerate any
4964 * PMD mappings, but PTE-mapped THP are fine. So let's simply refuse any
4965 * PMD mappings if THPs are disabled.
4966 */
4967 if (thp_disabled_by_hw() || vma_thp_disabled(vma, vma->vm_flags))
4968 return ret;
4969
4970 if (!thp_vma_suitable_order(vma, haddr, PMD_ORDER))
4971 return ret;
4972
4973 if (folio_order(folio) != HPAGE_PMD_ORDER)
4974 return ret;
4975 page = &folio->page;
4976
4977 /*
4978 * Just backoff if any subpage of a THP is corrupted otherwise
4979 * the corrupted page may mapped by PMD silently to escape the
4980 * check. This kind of THP just can be PTE mapped. Access to
4981 * the corrupted subpage should trigger SIGBUS as expected.
4982 */
4983 if (unlikely(folio_test_has_hwpoisoned(folio)))
4984 return ret;
4985
4986 /*
4987 * Archs like ppc64 need additional space to store information
4988 * related to pte entry. Use the preallocated table for that.
4989 */
4990 if (arch_needs_pgtable_deposit() && !vmf->prealloc_pte) {
4991 vmf->prealloc_pte = pte_alloc_one(vma->vm_mm);
4992 if (!vmf->prealloc_pte)
4993 return VM_FAULT_OOM;
4994 }
4995
4996 vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
4997 if (unlikely(!pmd_none(*vmf->pmd)))
4998 goto out;
4999
5000 flush_icache_pages(vma, page, HPAGE_PMD_NR);
5001
5002 entry = mk_huge_pmd(page, vma->vm_page_prot);
5003 if (write)
5004 entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
5005
5006 add_mm_counter(vma->vm_mm, mm_counter_file(folio), HPAGE_PMD_NR);
5007 folio_add_file_rmap_pmd(folio, page, vma);
5008
5009 /*
5010 * deposit and withdraw with pmd lock held
5011 */
5012 if (arch_needs_pgtable_deposit())
5013 deposit_prealloc_pte(vmf);
5014
5015 set_pmd_at(vma->vm_mm, haddr, vmf->pmd, entry);
5016
5017 update_mmu_cache_pmd(vma, haddr, vmf->pmd);
5018
5019 /* fault is handled */
5020 ret = 0;
5021 count_vm_event(THP_FILE_MAPPED);
5022out:
5023 spin_unlock(vmf->ptl);
5024 return ret;
5025}
5026#else
5027vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
5028{
5029 return VM_FAULT_FALLBACK;
5030}
5031#endif
5032
5033/**
5034 * set_pte_range - Set a range of PTEs to point to pages in a folio.
5035 * @vmf: Fault decription.
5036 * @folio: The folio that contains @page.
5037 * @page: The first page to create a PTE for.
5038 * @nr: The number of PTEs to create.
5039 * @addr: The first address to create a PTE for.
5040 */
5041void set_pte_range(struct vm_fault *vmf, struct folio *folio,
5042 struct page *page, unsigned int nr, unsigned long addr)
5043{
5044 struct vm_area_struct *vma = vmf->vma;
5045 bool write = vmf->flags & FAULT_FLAG_WRITE;
5046 bool prefault = !in_range(vmf->address, addr, nr * PAGE_SIZE);
5047 pte_t entry;
5048
5049 flush_icache_pages(vma, page, nr);
5050 entry = mk_pte(page, vma->vm_page_prot);
5051
5052 if (prefault && arch_wants_old_prefaulted_pte())
5053 entry = pte_mkold(entry);
5054 else
5055 entry = pte_sw_mkyoung(entry);
5056
5057 if (write)
5058 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
5059 if (unlikely(vmf_orig_pte_uffd_wp(vmf)))
5060 entry = pte_mkuffd_wp(entry);
5061 /* copy-on-write page */
5062 if (write && !(vma->vm_flags & VM_SHARED)) {
5063 VM_BUG_ON_FOLIO(nr != 1, folio);
5064 folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE);
5065 folio_add_lru_vma(folio, vma);
5066 } else {
5067 folio_add_file_rmap_ptes(folio, page, nr, vma);
5068 }
5069 set_ptes(vma->vm_mm, addr, vmf->pte, entry, nr);
5070
5071 /* no need to invalidate: a not-present page won't be cached */
5072 update_mmu_cache_range(vmf, vma, addr, vmf->pte, nr);
5073}
5074
5075static bool vmf_pte_changed(struct vm_fault *vmf)
5076{
5077 if (vmf->flags & FAULT_FLAG_ORIG_PTE_VALID)
5078 return !pte_same(ptep_get(vmf->pte), vmf->orig_pte);
5079
5080 return !pte_none(ptep_get(vmf->pte));
5081}
5082
5083/**
5084 * finish_fault - finish page fault once we have prepared the page to fault
5085 *
5086 * @vmf: structure describing the fault
5087 *
5088 * This function handles all that is needed to finish a page fault once the
5089 * page to fault in is prepared. It handles locking of PTEs, inserts PTE for
5090 * given page, adds reverse page mapping, handles memcg charges and LRU
5091 * addition.
5092 *
5093 * The function expects the page to be locked and on success it consumes a
5094 * reference of a page being mapped (for the PTE which maps it).
5095 *
5096 * Return: %0 on success, %VM_FAULT_ code in case of error.
5097 */
5098vm_fault_t finish_fault(struct vm_fault *vmf)
5099{
5100 struct vm_area_struct *vma = vmf->vma;
5101 struct page *page;
5102 struct folio *folio;
5103 vm_fault_t ret;
5104 bool is_cow = (vmf->flags & FAULT_FLAG_WRITE) &&
5105 !(vma->vm_flags & VM_SHARED);
5106 int type, nr_pages;
5107 unsigned long addr;
5108 bool needs_fallback = false;
5109
5110fallback:
5111 addr = vmf->address;
5112
5113 /* Did we COW the page? */
5114 if (is_cow)
5115 page = vmf->cow_page;
5116 else
5117 page = vmf->page;
5118
5119 /*
5120 * check even for read faults because we might have lost our CoWed
5121 * page
5122 */
5123 if (!(vma->vm_flags & VM_SHARED)) {
5124 ret = check_stable_address_space(vma->vm_mm);
5125 if (ret)
5126 return ret;
5127 }
5128
5129 if (pmd_none(*vmf->pmd)) {
5130 if (PageTransCompound(page)) {
5131 ret = do_set_pmd(vmf, page);
5132 if (ret != VM_FAULT_FALLBACK)
5133 return ret;
5134 }
5135
5136 if (vmf->prealloc_pte)
5137 pmd_install(vma->vm_mm, vmf->pmd, &vmf->prealloc_pte);
5138 else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd)))
5139 return VM_FAULT_OOM;
5140 }
5141
5142 folio = page_folio(page);
5143 nr_pages = folio_nr_pages(folio);
5144
5145 /*
5146 * Using per-page fault to maintain the uffd semantics, and same
5147 * approach also applies to non-anonymous-shmem faults to avoid
5148 * inflating the RSS of the process.
5149 */
5150 if (!vma_is_anon_shmem(vma) || unlikely(userfaultfd_armed(vma)) ||
5151 unlikely(needs_fallback)) {
5152 nr_pages = 1;
5153 } else if (nr_pages > 1) {
5154 pgoff_t idx = folio_page_idx(folio, page);
5155 /* The page offset of vmf->address within the VMA. */
5156 pgoff_t vma_off = vmf->pgoff - vmf->vma->vm_pgoff;
5157 /* The index of the entry in the pagetable for fault page. */
5158 pgoff_t pte_off = pte_index(vmf->address);
5159
5160 /*
5161 * Fallback to per-page fault in case the folio size in page
5162 * cache beyond the VMA limits and PMD pagetable limits.
5163 */
5164 if (unlikely(vma_off < idx ||
5165 vma_off + (nr_pages - idx) > vma_pages(vma) ||
5166 pte_off < idx ||
5167 pte_off + (nr_pages - idx) > PTRS_PER_PTE)) {
5168 nr_pages = 1;
5169 } else {
5170 /* Now we can set mappings for the whole large folio. */
5171 addr = vmf->address - idx * PAGE_SIZE;
5172 page = &folio->page;
5173 }
5174 }
5175
5176 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
5177 addr, &vmf->ptl);
5178 if (!vmf->pte)
5179 return VM_FAULT_NOPAGE;
5180
5181 /* Re-check under ptl */
5182 if (nr_pages == 1 && unlikely(vmf_pte_changed(vmf))) {
5183 update_mmu_tlb(vma, addr, vmf->pte);
5184 ret = VM_FAULT_NOPAGE;
5185 goto unlock;
5186 } else if (nr_pages > 1 && !pte_range_none(vmf->pte, nr_pages)) {
5187 needs_fallback = true;
5188 pte_unmap_unlock(vmf->pte, vmf->ptl);
5189 goto fallback;
5190 }
5191
5192 folio_ref_add(folio, nr_pages - 1);
5193 set_pte_range(vmf, folio, page, nr_pages, addr);
5194 type = is_cow ? MM_ANONPAGES : mm_counter_file(folio);
5195 add_mm_counter(vma->vm_mm, type, nr_pages);
5196 ret = 0;
5197
5198unlock:
5199 pte_unmap_unlock(vmf->pte, vmf->ptl);
5200 return ret;
5201}
5202
5203static unsigned long fault_around_pages __read_mostly =
5204 65536 >> PAGE_SHIFT;
5205
5206#ifdef CONFIG_DEBUG_FS
5207static int fault_around_bytes_get(void *data, u64 *val)
5208{
5209 *val = fault_around_pages << PAGE_SHIFT;
5210 return 0;
5211}
5212
5213/*
5214 * fault_around_bytes must be rounded down to the nearest page order as it's
5215 * what do_fault_around() expects to see.
5216 */
5217static int fault_around_bytes_set(void *data, u64 val)
5218{
5219 if (val / PAGE_SIZE > PTRS_PER_PTE)
5220 return -EINVAL;
5221
5222 /*
5223 * The minimum value is 1 page, however this results in no fault-around
5224 * at all. See should_fault_around().
5225 */
5226 val = max(val, PAGE_SIZE);
5227 fault_around_pages = rounddown_pow_of_two(val) >> PAGE_SHIFT;
5228
5229 return 0;
5230}
5231DEFINE_DEBUGFS_ATTRIBUTE(fault_around_bytes_fops,
5232 fault_around_bytes_get, fault_around_bytes_set, "%llu\n");
5233
5234static int __init fault_around_debugfs(void)
5235{
5236 debugfs_create_file_unsafe("fault_around_bytes", 0644, NULL, NULL,
5237 &fault_around_bytes_fops);
5238 return 0;
5239}
5240late_initcall(fault_around_debugfs);
5241#endif
5242
5243/*
5244 * do_fault_around() tries to map few pages around the fault address. The hope
5245 * is that the pages will be needed soon and this will lower the number of
5246 * faults to handle.
5247 *
5248 * It uses vm_ops->map_pages() to map the pages, which skips the page if it's
5249 * not ready to be mapped: not up-to-date, locked, etc.
5250 *
5251 * This function doesn't cross VMA or page table boundaries, in order to call
5252 * map_pages() and acquire a PTE lock only once.
5253 *
5254 * fault_around_pages defines how many pages we'll try to map.
5255 * do_fault_around() expects it to be set to a power of two less than or equal
5256 * to PTRS_PER_PTE.
5257 *
5258 * The virtual address of the area that we map is naturally aligned to
5259 * fault_around_pages * PAGE_SIZE rounded down to the machine page size
5260 * (and therefore to page order). This way it's easier to guarantee
5261 * that we don't cross page table boundaries.
5262 */
5263static vm_fault_t do_fault_around(struct vm_fault *vmf)
5264{
5265 pgoff_t nr_pages = READ_ONCE(fault_around_pages);
5266 pgoff_t pte_off = pte_index(vmf->address);
5267 /* The page offset of vmf->address within the VMA. */
5268 pgoff_t vma_off = vmf->pgoff - vmf->vma->vm_pgoff;
5269 pgoff_t from_pte, to_pte;
5270 vm_fault_t ret;
5271
5272 /* The PTE offset of the start address, clamped to the VMA. */
5273 from_pte = max(ALIGN_DOWN(pte_off, nr_pages),
5274 pte_off - min(pte_off, vma_off));
5275
5276 /* The PTE offset of the end address, clamped to the VMA and PTE. */
5277 to_pte = min3(from_pte + nr_pages, (pgoff_t)PTRS_PER_PTE,
5278 pte_off + vma_pages(vmf->vma) - vma_off) - 1;
5279
5280 if (pmd_none(*vmf->pmd)) {
5281 vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm);
5282 if (!vmf->prealloc_pte)
5283 return VM_FAULT_OOM;
5284 }
5285
5286 rcu_read_lock();
5287 ret = vmf->vma->vm_ops->map_pages(vmf,
5288 vmf->pgoff + from_pte - pte_off,
5289 vmf->pgoff + to_pte - pte_off);
5290 rcu_read_unlock();
5291
5292 return ret;
5293}
5294
5295/* Return true if we should do read fault-around, false otherwise */
5296static inline bool should_fault_around(struct vm_fault *vmf)
5297{
5298 /* No ->map_pages? No way to fault around... */
5299 if (!vmf->vma->vm_ops->map_pages)
5300 return false;
5301
5302 if (uffd_disable_fault_around(vmf->vma))
5303 return false;
5304
5305 /* A single page implies no faulting 'around' at all. */
5306 return fault_around_pages > 1;
5307}
5308
5309static vm_fault_t do_read_fault(struct vm_fault *vmf)
5310{
5311 vm_fault_t ret = 0;
5312 struct folio *folio;
5313
5314 /*
5315 * Let's call ->map_pages() first and use ->fault() as fallback
5316 * if page by the offset is not ready to be mapped (cold cache or
5317 * something).
5318 */
5319 if (should_fault_around(vmf)) {
5320 ret = do_fault_around(vmf);
5321 if (ret)
5322 return ret;
5323 }
5324
5325 ret = vmf_can_call_fault(vmf);
5326 if (ret)
5327 return ret;
5328
5329 ret = __do_fault(vmf);
5330 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
5331 return ret;
5332
5333 ret |= finish_fault(vmf);
5334 folio = page_folio(vmf->page);
5335 folio_unlock(folio);
5336 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
5337 folio_put(folio);
5338 return ret;
5339}
5340
5341static vm_fault_t do_cow_fault(struct vm_fault *vmf)
5342{
5343 struct vm_area_struct *vma = vmf->vma;
5344 struct folio *folio;
5345 vm_fault_t ret;
5346
5347 ret = vmf_can_call_fault(vmf);
5348 if (!ret)
5349 ret = vmf_anon_prepare(vmf);
5350 if (ret)
5351 return ret;
5352
5353 folio = folio_prealloc(vma->vm_mm, vma, vmf->address, false);
5354 if (!folio)
5355 return VM_FAULT_OOM;
5356
5357 vmf->cow_page = &folio->page;
5358
5359 ret = __do_fault(vmf);
5360 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
5361 goto uncharge_out;
5362 if (ret & VM_FAULT_DONE_COW)
5363 return ret;
5364
5365 if (copy_mc_user_highpage(vmf->cow_page, vmf->page, vmf->address, vma)) {
5366 ret = VM_FAULT_HWPOISON;
5367 goto unlock;
5368 }
5369 __folio_mark_uptodate(folio);
5370
5371 ret |= finish_fault(vmf);
5372unlock:
5373 unlock_page(vmf->page);
5374 put_page(vmf->page);
5375 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
5376 goto uncharge_out;
5377 return ret;
5378uncharge_out:
5379 folio_put(folio);
5380 return ret;
5381}
5382
5383static vm_fault_t do_shared_fault(struct vm_fault *vmf)
5384{
5385 struct vm_area_struct *vma = vmf->vma;
5386 vm_fault_t ret, tmp;
5387 struct folio *folio;
5388
5389 ret = vmf_can_call_fault(vmf);
5390 if (ret)
5391 return ret;
5392
5393 ret = __do_fault(vmf);
5394 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
5395 return ret;
5396
5397 folio = page_folio(vmf->page);
5398
5399 /*
5400 * Check if the backing address space wants to know that the page is
5401 * about to become writable
5402 */
5403 if (vma->vm_ops->page_mkwrite) {
5404 folio_unlock(folio);
5405 tmp = do_page_mkwrite(vmf, folio);
5406 if (unlikely(!tmp ||
5407 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
5408 folio_put(folio);
5409 return tmp;
5410 }
5411 }
5412
5413 ret |= finish_fault(vmf);
5414 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE |
5415 VM_FAULT_RETRY))) {
5416 folio_unlock(folio);
5417 folio_put(folio);
5418 return ret;
5419 }
5420
5421 ret |= fault_dirty_shared_page(vmf);
5422 return ret;
5423}
5424
5425/*
5426 * We enter with non-exclusive mmap_lock (to exclude vma changes,
5427 * but allow concurrent faults).
5428 * The mmap_lock may have been released depending on flags and our
5429 * return value. See filemap_fault() and __folio_lock_or_retry().
5430 * If mmap_lock is released, vma may become invalid (for example
5431 * by other thread calling munmap()).
5432 */
5433static vm_fault_t do_fault(struct vm_fault *vmf)
5434{
5435 struct vm_area_struct *vma = vmf->vma;
5436 struct mm_struct *vm_mm = vma->vm_mm;
5437 vm_fault_t ret;
5438
5439 /*
5440 * The VMA was not fully populated on mmap() or missing VM_DONTEXPAND
5441 */
5442 if (!vma->vm_ops->fault) {
5443 vmf->pte = pte_offset_map_lock(vmf->vma->vm_mm, vmf->pmd,
5444 vmf->address, &vmf->ptl);
5445 if (unlikely(!vmf->pte))
5446 ret = VM_FAULT_SIGBUS;
5447 else {
5448 /*
5449 * Make sure this is not a temporary clearing of pte
5450 * by holding ptl and checking again. A R/M/W update
5451 * of pte involves: take ptl, clearing the pte so that
5452 * we don't have concurrent modification by hardware
5453 * followed by an update.
5454 */
5455 if (unlikely(pte_none(ptep_get(vmf->pte))))
5456 ret = VM_FAULT_SIGBUS;
5457 else
5458 ret = VM_FAULT_NOPAGE;
5459
5460 pte_unmap_unlock(vmf->pte, vmf->ptl);
5461 }
5462 } else if (!(vmf->flags & FAULT_FLAG_WRITE))
5463 ret = do_read_fault(vmf);
5464 else if (!(vma->vm_flags & VM_SHARED))
5465 ret = do_cow_fault(vmf);
5466 else
5467 ret = do_shared_fault(vmf);
5468
5469 /* preallocated pagetable is unused: free it */
5470 if (vmf->prealloc_pte) {
5471 pte_free(vm_mm, vmf->prealloc_pte);
5472 vmf->prealloc_pte = NULL;
5473 }
5474 return ret;
5475}
5476
5477int numa_migrate_check(struct folio *folio, struct vm_fault *vmf,
5478 unsigned long addr, int *flags,
5479 bool writable, int *last_cpupid)
5480{
5481 struct vm_area_struct *vma = vmf->vma;
5482
5483 /*
5484 * Avoid grouping on RO pages in general. RO pages shouldn't hurt as
5485 * much anyway since they can be in shared cache state. This misses
5486 * the case where a mapping is writable but the process never writes
5487 * to it but pte_write gets cleared during protection updates and
5488 * pte_dirty has unpredictable behaviour between PTE scan updates,
5489 * background writeback, dirty balancing and application behaviour.
5490 */
5491 if (!writable)
5492 *flags |= TNF_NO_GROUP;
5493
5494 /*
5495 * Flag if the folio is shared between multiple address spaces. This
5496 * is later used when determining whether to group tasks together
5497 */
5498 if (folio_likely_mapped_shared(folio) && (vma->vm_flags & VM_SHARED))
5499 *flags |= TNF_SHARED;
5500 /*
5501 * For memory tiering mode, cpupid of slow memory page is used
5502 * to record page access time. So use default value.
5503 */
5504 if (folio_use_access_time(folio))
5505 *last_cpupid = (-1 & LAST_CPUPID_MASK);
5506 else
5507 *last_cpupid = folio_last_cpupid(folio);
5508
5509 /* Record the current PID acceesing VMA */
5510 vma_set_access_pid_bit(vma);
5511
5512 count_vm_numa_event(NUMA_HINT_FAULTS);
5513#ifdef CONFIG_NUMA_BALANCING
5514 count_memcg_folio_events(folio, NUMA_HINT_FAULTS, 1);
5515#endif
5516 if (folio_nid(folio) == numa_node_id()) {
5517 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
5518 *flags |= TNF_FAULT_LOCAL;
5519 }
5520
5521 return mpol_misplaced(folio, vmf, addr);
5522}
5523
5524static void numa_rebuild_single_mapping(struct vm_fault *vmf, struct vm_area_struct *vma,
5525 unsigned long fault_addr, pte_t *fault_pte,
5526 bool writable)
5527{
5528 pte_t pte, old_pte;
5529
5530 old_pte = ptep_modify_prot_start(vma, fault_addr, fault_pte);
5531 pte = pte_modify(old_pte, vma->vm_page_prot);
5532 pte = pte_mkyoung(pte);
5533 if (writable)
5534 pte = pte_mkwrite(pte, vma);
5535 ptep_modify_prot_commit(vma, fault_addr, fault_pte, old_pte, pte);
5536 update_mmu_cache_range(vmf, vma, fault_addr, fault_pte, 1);
5537}
5538
5539static void numa_rebuild_large_mapping(struct vm_fault *vmf, struct vm_area_struct *vma,
5540 struct folio *folio, pte_t fault_pte,
5541 bool ignore_writable, bool pte_write_upgrade)
5542{
5543 int nr = pte_pfn(fault_pte) - folio_pfn(folio);
5544 unsigned long start, end, addr = vmf->address;
5545 unsigned long addr_start = addr - (nr << PAGE_SHIFT);
5546 unsigned long pt_start = ALIGN_DOWN(addr, PMD_SIZE);
5547 pte_t *start_ptep;
5548
5549 /* Stay within the VMA and within the page table. */
5550 start = max3(addr_start, pt_start, vma->vm_start);
5551 end = min3(addr_start + folio_size(folio), pt_start + PMD_SIZE,
5552 vma->vm_end);
5553 start_ptep = vmf->pte - ((addr - start) >> PAGE_SHIFT);
5554
5555 /* Restore all PTEs' mapping of the large folio */
5556 for (addr = start; addr != end; start_ptep++, addr += PAGE_SIZE) {
5557 pte_t ptent = ptep_get(start_ptep);
5558 bool writable = false;
5559
5560 if (!pte_present(ptent) || !pte_protnone(ptent))
5561 continue;
5562
5563 if (pfn_folio(pte_pfn(ptent)) != folio)
5564 continue;
5565
5566 if (!ignore_writable) {
5567 ptent = pte_modify(ptent, vma->vm_page_prot);
5568 writable = pte_write(ptent);
5569 if (!writable && pte_write_upgrade &&
5570 can_change_pte_writable(vma, addr, ptent))
5571 writable = true;
5572 }
5573
5574 numa_rebuild_single_mapping(vmf, vma, addr, start_ptep, writable);
5575 }
5576}
5577
5578static vm_fault_t do_numa_page(struct vm_fault *vmf)
5579{
5580 struct vm_area_struct *vma = vmf->vma;
5581 struct folio *folio = NULL;
5582 int nid = NUMA_NO_NODE;
5583 bool writable = false, ignore_writable = false;
5584 bool pte_write_upgrade = vma_wants_manual_pte_write_upgrade(vma);
5585 int last_cpupid;
5586 int target_nid;
5587 pte_t pte, old_pte;
5588 int flags = 0, nr_pages;
5589
5590 /*
5591 * The pte cannot be used safely until we verify, while holding the page
5592 * table lock, that its contents have not changed during fault handling.
5593 */
5594 spin_lock(vmf->ptl);
5595 /* Read the live PTE from the page tables: */
5596 old_pte = ptep_get(vmf->pte);
5597
5598 if (unlikely(!pte_same(old_pte, vmf->orig_pte))) {
5599 pte_unmap_unlock(vmf->pte, vmf->ptl);
5600 return 0;
5601 }
5602
5603 pte = pte_modify(old_pte, vma->vm_page_prot);
5604
5605 /*
5606 * Detect now whether the PTE could be writable; this information
5607 * is only valid while holding the PT lock.
5608 */
5609 writable = pte_write(pte);
5610 if (!writable && pte_write_upgrade &&
5611 can_change_pte_writable(vma, vmf->address, pte))
5612 writable = true;
5613
5614 folio = vm_normal_folio(vma, vmf->address, pte);
5615 if (!folio || folio_is_zone_device(folio))
5616 goto out_map;
5617
5618 nid = folio_nid(folio);
5619 nr_pages = folio_nr_pages(folio);
5620
5621 target_nid = numa_migrate_check(folio, vmf, vmf->address, &flags,
5622 writable, &last_cpupid);
5623 if (target_nid == NUMA_NO_NODE)
5624 goto out_map;
5625 if (migrate_misplaced_folio_prepare(folio, vma, target_nid)) {
5626 flags |= TNF_MIGRATE_FAIL;
5627 goto out_map;
5628 }
5629 /* The folio is isolated and isolation code holds a folio reference. */
5630 pte_unmap_unlock(vmf->pte, vmf->ptl);
5631 writable = false;
5632 ignore_writable = true;
5633
5634 /* Migrate to the requested node */
5635 if (!migrate_misplaced_folio(folio, vma, target_nid)) {
5636 nid = target_nid;
5637 flags |= TNF_MIGRATED;
5638 task_numa_fault(last_cpupid, nid, nr_pages, flags);
5639 return 0;
5640 }
5641
5642 flags |= TNF_MIGRATE_FAIL;
5643 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd,
5644 vmf->address, &vmf->ptl);
5645 if (unlikely(!vmf->pte))
5646 return 0;
5647 if (unlikely(!pte_same(ptep_get(vmf->pte), vmf->orig_pte))) {
5648 pte_unmap_unlock(vmf->pte, vmf->ptl);
5649 return 0;
5650 }
5651out_map:
5652 /*
5653 * Make it present again, depending on how arch implements
5654 * non-accessible ptes, some can allow access by kernel mode.
5655 */
5656 if (folio && folio_test_large(folio))
5657 numa_rebuild_large_mapping(vmf, vma, folio, pte, ignore_writable,
5658 pte_write_upgrade);
5659 else
5660 numa_rebuild_single_mapping(vmf, vma, vmf->address, vmf->pte,
5661 writable);
5662 pte_unmap_unlock(vmf->pte, vmf->ptl);
5663
5664 if (nid != NUMA_NO_NODE)
5665 task_numa_fault(last_cpupid, nid, nr_pages, flags);
5666 return 0;
5667}
5668
5669static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf)
5670{
5671 struct vm_area_struct *vma = vmf->vma;
5672 if (vma_is_anonymous(vma))
5673 return do_huge_pmd_anonymous_page(vmf);
5674 if (vma->vm_ops->huge_fault)
5675 return vma->vm_ops->huge_fault(vmf, PMD_ORDER);
5676 return VM_FAULT_FALLBACK;
5677}
5678
5679/* `inline' is required to avoid gcc 4.1.2 build error */
5680static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf)
5681{
5682 struct vm_area_struct *vma = vmf->vma;
5683 const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE;
5684 vm_fault_t ret;
5685
5686 if (vma_is_anonymous(vma)) {
5687 if (likely(!unshare) &&
5688 userfaultfd_huge_pmd_wp(vma, vmf->orig_pmd)) {
5689 if (userfaultfd_wp_async(vmf->vma))
5690 goto split;
5691 return handle_userfault(vmf, VM_UFFD_WP);
5692 }
5693 return do_huge_pmd_wp_page(vmf);
5694 }
5695
5696 if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
5697 if (vma->vm_ops->huge_fault) {
5698 ret = vma->vm_ops->huge_fault(vmf, PMD_ORDER);
5699 if (!(ret & VM_FAULT_FALLBACK))
5700 return ret;
5701 }
5702 }
5703
5704split:
5705 /* COW or write-notify handled on pte level: split pmd. */
5706 __split_huge_pmd(vma, vmf->pmd, vmf->address, false, NULL);
5707
5708 return VM_FAULT_FALLBACK;
5709}
5710
5711static vm_fault_t create_huge_pud(struct vm_fault *vmf)
5712{
5713#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
5714 defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
5715 struct vm_area_struct *vma = vmf->vma;
5716 /* No support for anonymous transparent PUD pages yet */
5717 if (vma_is_anonymous(vma))
5718 return VM_FAULT_FALLBACK;
5719 if (vma->vm_ops->huge_fault)
5720 return vma->vm_ops->huge_fault(vmf, PUD_ORDER);
5721#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
5722 return VM_FAULT_FALLBACK;
5723}
5724
5725static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud)
5726{
5727#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \
5728 defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD)
5729 struct vm_area_struct *vma = vmf->vma;
5730 vm_fault_t ret;
5731
5732 /* No support for anonymous transparent PUD pages yet */
5733 if (vma_is_anonymous(vma))
5734 goto split;
5735 if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) {
5736 if (vma->vm_ops->huge_fault) {
5737 ret = vma->vm_ops->huge_fault(vmf, PUD_ORDER);
5738 if (!(ret & VM_FAULT_FALLBACK))
5739 return ret;
5740 }
5741 }
5742split:
5743 /* COW or write-notify not handled on PUD level: split pud.*/
5744 __split_huge_pud(vma, vmf->pud, vmf->address);
5745#endif /* CONFIG_TRANSPARENT_HUGEPAGE && CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD */
5746 return VM_FAULT_FALLBACK;
5747}
5748
5749/*
5750 * These routines also need to handle stuff like marking pages dirty
5751 * and/or accessed for architectures that don't do it in hardware (most
5752 * RISC architectures). The early dirtying is also good on the i386.
5753 *
5754 * There is also a hook called "update_mmu_cache()" that architectures
5755 * with external mmu caches can use to update those (ie the Sparc or
5756 * PowerPC hashed page tables that act as extended TLBs).
5757 *
5758 * We enter with non-exclusive mmap_lock (to exclude vma changes, but allow
5759 * concurrent faults).
5760 *
5761 * The mmap_lock may have been released depending on flags and our return value.
5762 * See filemap_fault() and __folio_lock_or_retry().
5763 */
5764static vm_fault_t handle_pte_fault(struct vm_fault *vmf)
5765{
5766 pte_t entry;
5767
5768 if (unlikely(pmd_none(*vmf->pmd))) {
5769 /*
5770 * Leave __pte_alloc() until later: because vm_ops->fault may
5771 * want to allocate huge page, and if we expose page table
5772 * for an instant, it will be difficult to retract from
5773 * concurrent faults and from rmap lookups.
5774 */
5775 vmf->pte = NULL;
5776 vmf->flags &= ~FAULT_FLAG_ORIG_PTE_VALID;
5777 } else {
5778 pmd_t dummy_pmdval;
5779
5780 /*
5781 * A regular pmd is established and it can't morph into a huge
5782 * pmd by anon khugepaged, since that takes mmap_lock in write
5783 * mode; but shmem or file collapse to THP could still morph
5784 * it into a huge pmd: just retry later if so.
5785 *
5786 * Use the maywrite version to indicate that vmf->pte may be
5787 * modified, but since we will use pte_same() to detect the
5788 * change of the !pte_none() entry, there is no need to recheck
5789 * the pmdval. Here we chooes to pass a dummy variable instead
5790 * of NULL, which helps new user think about why this place is
5791 * special.
5792 */
5793 vmf->pte = pte_offset_map_rw_nolock(vmf->vma->vm_mm, vmf->pmd,
5794 vmf->address, &dummy_pmdval,
5795 &vmf->ptl);
5796 if (unlikely(!vmf->pte))
5797 return 0;
5798 vmf->orig_pte = ptep_get_lockless(vmf->pte);
5799 vmf->flags |= FAULT_FLAG_ORIG_PTE_VALID;
5800
5801 if (pte_none(vmf->orig_pte)) {
5802 pte_unmap(vmf->pte);
5803 vmf->pte = NULL;
5804 }
5805 }
5806
5807 if (!vmf->pte)
5808 return do_pte_missing(vmf);
5809
5810 if (!pte_present(vmf->orig_pte))
5811 return do_swap_page(vmf);
5812
5813 if (pte_protnone(vmf->orig_pte) && vma_is_accessible(vmf->vma))
5814 return do_numa_page(vmf);
5815
5816 spin_lock(vmf->ptl);
5817 entry = vmf->orig_pte;
5818 if (unlikely(!pte_same(ptep_get(vmf->pte), entry))) {
5819 update_mmu_tlb(vmf->vma, vmf->address, vmf->pte);
5820 goto unlock;
5821 }
5822 if (vmf->flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) {
5823 if (!pte_write(entry))
5824 return do_wp_page(vmf);
5825 else if (likely(vmf->flags & FAULT_FLAG_WRITE))
5826 entry = pte_mkdirty(entry);
5827 }
5828 entry = pte_mkyoung(entry);
5829 if (ptep_set_access_flags(vmf->vma, vmf->address, vmf->pte, entry,
5830 vmf->flags & FAULT_FLAG_WRITE)) {
5831 update_mmu_cache_range(vmf, vmf->vma, vmf->address,
5832 vmf->pte, 1);
5833 } else {
5834 /* Skip spurious TLB flush for retried page fault */
5835 if (vmf->flags & FAULT_FLAG_TRIED)
5836 goto unlock;
5837 /*
5838 * This is needed only for protection faults but the arch code
5839 * is not yet telling us if this is a protection fault or not.
5840 * This still avoids useless tlb flushes for .text page faults
5841 * with threads.
5842 */
5843 if (vmf->flags & FAULT_FLAG_WRITE)
5844 flush_tlb_fix_spurious_fault(vmf->vma, vmf->address,
5845 vmf->pte);
5846 }
5847unlock:
5848 pte_unmap_unlock(vmf->pte, vmf->ptl);
5849 return 0;
5850}
5851
5852/*
5853 * On entry, we hold either the VMA lock or the mmap_lock
5854 * (FAULT_FLAG_VMA_LOCK tells you which). If VM_FAULT_RETRY is set in
5855 * the result, the mmap_lock is not held on exit. See filemap_fault()
5856 * and __folio_lock_or_retry().
5857 */
5858static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma,
5859 unsigned long address, unsigned int flags)
5860{
5861 struct vm_fault vmf = {
5862 .vma = vma,
5863 .address = address & PAGE_MASK,
5864 .real_address = address,
5865 .flags = flags,
5866 .pgoff = linear_page_index(vma, address),
5867 .gfp_mask = __get_fault_gfp_mask(vma),
5868 };
5869 struct mm_struct *mm = vma->vm_mm;
5870 unsigned long vm_flags = vma->vm_flags;
5871 pgd_t *pgd;
5872 p4d_t *p4d;
5873 vm_fault_t ret;
5874
5875 pgd = pgd_offset(mm, address);
5876 p4d = p4d_alloc(mm, pgd, address);
5877 if (!p4d)
5878 return VM_FAULT_OOM;
5879
5880 vmf.pud = pud_alloc(mm, p4d, address);
5881 if (!vmf.pud)
5882 return VM_FAULT_OOM;
5883retry_pud:
5884 if (pud_none(*vmf.pud) &&
5885 thp_vma_allowable_order(vma, vm_flags,
5886 TVA_IN_PF | TVA_ENFORCE_SYSFS, PUD_ORDER)) {
5887 ret = create_huge_pud(&vmf);
5888 if (!(ret & VM_FAULT_FALLBACK))
5889 return ret;
5890 } else {
5891 pud_t orig_pud = *vmf.pud;
5892
5893 barrier();
5894 if (pud_trans_huge(orig_pud) || pud_devmap(orig_pud)) {
5895
5896 /*
5897 * TODO once we support anonymous PUDs: NUMA case and
5898 * FAULT_FLAG_UNSHARE handling.
5899 */
5900 if ((flags & FAULT_FLAG_WRITE) && !pud_write(orig_pud)) {
5901 ret = wp_huge_pud(&vmf, orig_pud);
5902 if (!(ret & VM_FAULT_FALLBACK))
5903 return ret;
5904 } else {
5905 huge_pud_set_accessed(&vmf, orig_pud);
5906 return 0;
5907 }
5908 }
5909 }
5910
5911 vmf.pmd = pmd_alloc(mm, vmf.pud, address);
5912 if (!vmf.pmd)
5913 return VM_FAULT_OOM;
5914
5915 /* Huge pud page fault raced with pmd_alloc? */
5916 if (pud_trans_unstable(vmf.pud))
5917 goto retry_pud;
5918
5919 if (pmd_none(*vmf.pmd) &&
5920 thp_vma_allowable_order(vma, vm_flags,
5921 TVA_IN_PF | TVA_ENFORCE_SYSFS, PMD_ORDER)) {
5922 ret = create_huge_pmd(&vmf);
5923 if (!(ret & VM_FAULT_FALLBACK))
5924 return ret;
5925 } else {
5926 vmf.orig_pmd = pmdp_get_lockless(vmf.pmd);
5927
5928 if (unlikely(is_swap_pmd(vmf.orig_pmd))) {
5929 VM_BUG_ON(thp_migration_supported() &&
5930 !is_pmd_migration_entry(vmf.orig_pmd));
5931 if (is_pmd_migration_entry(vmf.orig_pmd))
5932 pmd_migration_entry_wait(mm, vmf.pmd);
5933 return 0;
5934 }
5935 if (pmd_trans_huge(vmf.orig_pmd) || pmd_devmap(vmf.orig_pmd)) {
5936 if (pmd_protnone(vmf.orig_pmd) && vma_is_accessible(vma))
5937 return do_huge_pmd_numa_page(&vmf);
5938
5939 if ((flags & (FAULT_FLAG_WRITE|FAULT_FLAG_UNSHARE)) &&
5940 !pmd_write(vmf.orig_pmd)) {
5941 ret = wp_huge_pmd(&vmf);
5942 if (!(ret & VM_FAULT_FALLBACK))
5943 return ret;
5944 } else {
5945 huge_pmd_set_accessed(&vmf);
5946 return 0;
5947 }
5948 }
5949 }
5950
5951 return handle_pte_fault(&vmf);
5952}
5953
5954/**
5955 * mm_account_fault - Do page fault accounting
5956 * @mm: mm from which memcg should be extracted. It can be NULL.
5957 * @regs: the pt_regs struct pointer. When set to NULL, will skip accounting
5958 * of perf event counters, but we'll still do the per-task accounting to
5959 * the task who triggered this page fault.
5960 * @address: the faulted address.
5961 * @flags: the fault flags.
5962 * @ret: the fault retcode.
5963 *
5964 * This will take care of most of the page fault accounting. Meanwhile, it
5965 * will also include the PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN] perf counter
5966 * updates. However, note that the handling of PERF_COUNT_SW_PAGE_FAULTS should
5967 * still be in per-arch page fault handlers at the entry of page fault.
5968 */
5969static inline void mm_account_fault(struct mm_struct *mm, struct pt_regs *regs,
5970 unsigned long address, unsigned int flags,
5971 vm_fault_t ret)
5972{
5973 bool major;
5974
5975 /* Incomplete faults will be accounted upon completion. */
5976 if (ret & VM_FAULT_RETRY)
5977 return;
5978
5979 /*
5980 * To preserve the behavior of older kernels, PGFAULT counters record
5981 * both successful and failed faults, as opposed to perf counters,
5982 * which ignore failed cases.
5983 */
5984 count_vm_event(PGFAULT);
5985 count_memcg_event_mm(mm, PGFAULT);
5986
5987 /*
5988 * Do not account for unsuccessful faults (e.g. when the address wasn't
5989 * valid). That includes arch_vma_access_permitted() failing before
5990 * reaching here. So this is not a "this many hardware page faults"
5991 * counter. We should use the hw profiling for that.
5992 */
5993 if (ret & VM_FAULT_ERROR)
5994 return;
5995
5996 /*
5997 * We define the fault as a major fault when the final successful fault
5998 * is VM_FAULT_MAJOR, or if it retried (which implies that we couldn't
5999 * handle it immediately previously).
6000 */
6001 major = (ret & VM_FAULT_MAJOR) || (flags & FAULT_FLAG_TRIED);
6002
6003 if (major)
6004 current->maj_flt++;
6005 else
6006 current->min_flt++;
6007
6008 /*
6009 * If the fault is done for GUP, regs will be NULL. We only do the
6010 * accounting for the per thread fault counters who triggered the
6011 * fault, and we skip the perf event updates.
6012 */
6013 if (!regs)
6014 return;
6015
6016 if (major)
6017 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MAJ, 1, regs, address);
6018 else
6019 perf_sw_event(PERF_COUNT_SW_PAGE_FAULTS_MIN, 1, regs, address);
6020}
6021
6022#ifdef CONFIG_LRU_GEN
6023static void lru_gen_enter_fault(struct vm_area_struct *vma)
6024{
6025 /* the LRU algorithm only applies to accesses with recency */
6026 current->in_lru_fault = vma_has_recency(vma);
6027}
6028
6029static void lru_gen_exit_fault(void)
6030{
6031 current->in_lru_fault = false;
6032}
6033#else
6034static void lru_gen_enter_fault(struct vm_area_struct *vma)
6035{
6036}
6037
6038static void lru_gen_exit_fault(void)
6039{
6040}
6041#endif /* CONFIG_LRU_GEN */
6042
6043static vm_fault_t sanitize_fault_flags(struct vm_area_struct *vma,
6044 unsigned int *flags)
6045{
6046 if (unlikely(*flags & FAULT_FLAG_UNSHARE)) {
6047 if (WARN_ON_ONCE(*flags & FAULT_FLAG_WRITE))
6048 return VM_FAULT_SIGSEGV;
6049 /*
6050 * FAULT_FLAG_UNSHARE only applies to COW mappings. Let's
6051 * just treat it like an ordinary read-fault otherwise.
6052 */
6053 if (!is_cow_mapping(vma->vm_flags))
6054 *flags &= ~FAULT_FLAG_UNSHARE;
6055 } else if (*flags & FAULT_FLAG_WRITE) {
6056 /* Write faults on read-only mappings are impossible ... */
6057 if (WARN_ON_ONCE(!(vma->vm_flags & VM_MAYWRITE)))
6058 return VM_FAULT_SIGSEGV;
6059 /* ... and FOLL_FORCE only applies to COW mappings. */
6060 if (WARN_ON_ONCE(!(vma->vm_flags & VM_WRITE) &&
6061 !is_cow_mapping(vma->vm_flags)))
6062 return VM_FAULT_SIGSEGV;
6063 }
6064#ifdef CONFIG_PER_VMA_LOCK
6065 /*
6066 * Per-VMA locks can't be used with FAULT_FLAG_RETRY_NOWAIT because of
6067 * the assumption that lock is dropped on VM_FAULT_RETRY.
6068 */
6069 if (WARN_ON_ONCE((*flags &
6070 (FAULT_FLAG_VMA_LOCK | FAULT_FLAG_RETRY_NOWAIT)) ==
6071 (FAULT_FLAG_VMA_LOCK | FAULT_FLAG_RETRY_NOWAIT)))
6072 return VM_FAULT_SIGSEGV;
6073#endif
6074
6075 return 0;
6076}
6077
6078/*
6079 * By the time we get here, we already hold the mm semaphore
6080 *
6081 * The mmap_lock may have been released depending on flags and our
6082 * return value. See filemap_fault() and __folio_lock_or_retry().
6083 */
6084vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
6085 unsigned int flags, struct pt_regs *regs)
6086{
6087 /* If the fault handler drops the mmap_lock, vma may be freed */
6088 struct mm_struct *mm = vma->vm_mm;
6089 vm_fault_t ret;
6090 bool is_droppable;
6091
6092 __set_current_state(TASK_RUNNING);
6093
6094 ret = sanitize_fault_flags(vma, &flags);
6095 if (ret)
6096 goto out;
6097
6098 if (!arch_vma_access_permitted(vma, flags & FAULT_FLAG_WRITE,
6099 flags & FAULT_FLAG_INSTRUCTION,
6100 flags & FAULT_FLAG_REMOTE)) {
6101 ret = VM_FAULT_SIGSEGV;
6102 goto out;
6103 }
6104
6105 is_droppable = !!(vma->vm_flags & VM_DROPPABLE);
6106
6107 /*
6108 * Enable the memcg OOM handling for faults triggered in user
6109 * space. Kernel faults are handled more gracefully.
6110 */
6111 if (flags & FAULT_FLAG_USER)
6112 mem_cgroup_enter_user_fault();
6113
6114 lru_gen_enter_fault(vma);
6115
6116 if (unlikely(is_vm_hugetlb_page(vma)))
6117 ret = hugetlb_fault(vma->vm_mm, vma, address, flags);
6118 else
6119 ret = __handle_mm_fault(vma, address, flags);
6120
6121 /*
6122 * Warning: It is no longer safe to dereference vma-> after this point,
6123 * because mmap_lock might have been dropped by __handle_mm_fault(), so
6124 * vma might be destroyed from underneath us.
6125 */
6126
6127 lru_gen_exit_fault();
6128
6129 /* If the mapping is droppable, then errors due to OOM aren't fatal. */
6130 if (is_droppable)
6131 ret &= ~VM_FAULT_OOM;
6132
6133 if (flags & FAULT_FLAG_USER) {
6134 mem_cgroup_exit_user_fault();
6135 /*
6136 * The task may have entered a memcg OOM situation but
6137 * if the allocation error was handled gracefully (no
6138 * VM_FAULT_OOM), there is no need to kill anything.
6139 * Just clean up the OOM state peacefully.
6140 */
6141 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
6142 mem_cgroup_oom_synchronize(false);
6143 }
6144out:
6145 mm_account_fault(mm, regs, address, flags, ret);
6146
6147 return ret;
6148}
6149EXPORT_SYMBOL_GPL(handle_mm_fault);
6150
6151#ifdef CONFIG_LOCK_MM_AND_FIND_VMA
6152#include <linux/extable.h>
6153
6154static inline bool get_mmap_lock_carefully(struct mm_struct *mm, struct pt_regs *regs)
6155{
6156 if (likely(mmap_read_trylock(mm)))
6157 return true;
6158
6159 if (regs && !user_mode(regs)) {
6160 unsigned long ip = exception_ip(regs);
6161 if (!search_exception_tables(ip))
6162 return false;
6163 }
6164
6165 return !mmap_read_lock_killable(mm);
6166}
6167
6168static inline bool mmap_upgrade_trylock(struct mm_struct *mm)
6169{
6170 /*
6171 * We don't have this operation yet.
6172 *
6173 * It should be easy enough to do: it's basically a
6174 * atomic_long_try_cmpxchg_acquire()
6175 * from RWSEM_READER_BIAS -> RWSEM_WRITER_LOCKED, but
6176 * it also needs the proper lockdep magic etc.
6177 */
6178 return false;
6179}
6180
6181static inline bool upgrade_mmap_lock_carefully(struct mm_struct *mm, struct pt_regs *regs)
6182{
6183 mmap_read_unlock(mm);
6184 if (regs && !user_mode(regs)) {
6185 unsigned long ip = exception_ip(regs);
6186 if (!search_exception_tables(ip))
6187 return false;
6188 }
6189 return !mmap_write_lock_killable(mm);
6190}
6191
6192/*
6193 * Helper for page fault handling.
6194 *
6195 * This is kind of equivalend to "mmap_read_lock()" followed
6196 * by "find_extend_vma()", except it's a lot more careful about
6197 * the locking (and will drop the lock on failure).
6198 *
6199 * For example, if we have a kernel bug that causes a page
6200 * fault, we don't want to just use mmap_read_lock() to get
6201 * the mm lock, because that would deadlock if the bug were
6202 * to happen while we're holding the mm lock for writing.
6203 *
6204 * So this checks the exception tables on kernel faults in
6205 * order to only do this all for instructions that are actually
6206 * expected to fault.
6207 *
6208 * We can also actually take the mm lock for writing if we
6209 * need to extend the vma, which helps the VM layer a lot.
6210 */
6211struct vm_area_struct *lock_mm_and_find_vma(struct mm_struct *mm,
6212 unsigned long addr, struct pt_regs *regs)
6213{
6214 struct vm_area_struct *vma;
6215
6216 if (!get_mmap_lock_carefully(mm, regs))
6217 return NULL;
6218
6219 vma = find_vma(mm, addr);
6220 if (likely(vma && (vma->vm_start <= addr)))
6221 return vma;
6222
6223 /*
6224 * Well, dang. We might still be successful, but only
6225 * if we can extend a vma to do so.
6226 */
6227 if (!vma || !(vma->vm_flags & VM_GROWSDOWN)) {
6228 mmap_read_unlock(mm);
6229 return NULL;
6230 }
6231
6232 /*
6233 * We can try to upgrade the mmap lock atomically,
6234 * in which case we can continue to use the vma
6235 * we already looked up.
6236 *
6237 * Otherwise we'll have to drop the mmap lock and
6238 * re-take it, and also look up the vma again,
6239 * re-checking it.
6240 */
6241 if (!mmap_upgrade_trylock(mm)) {
6242 if (!upgrade_mmap_lock_carefully(mm, regs))
6243 return NULL;
6244
6245 vma = find_vma(mm, addr);
6246 if (!vma)
6247 goto fail;
6248 if (vma->vm_start <= addr)
6249 goto success;
6250 if (!(vma->vm_flags & VM_GROWSDOWN))
6251 goto fail;
6252 }
6253
6254 if (expand_stack_locked(vma, addr))
6255 goto fail;
6256
6257success:
6258 mmap_write_downgrade(mm);
6259 return vma;
6260
6261fail:
6262 mmap_write_unlock(mm);
6263 return NULL;
6264}
6265#endif
6266
6267#ifdef CONFIG_PER_VMA_LOCK
6268/*
6269 * Lookup and lock a VMA under RCU protection. Returned VMA is guaranteed to be
6270 * stable and not isolated. If the VMA is not found or is being modified the
6271 * function returns NULL.
6272 */
6273struct vm_area_struct *lock_vma_under_rcu(struct mm_struct *mm,
6274 unsigned long address)
6275{
6276 MA_STATE(mas, &mm->mm_mt, address, address);
6277 struct vm_area_struct *vma;
6278
6279 rcu_read_lock();
6280retry:
6281 vma = mas_walk(&mas);
6282 if (!vma)
6283 goto inval;
6284
6285 if (!vma_start_read(vma))
6286 goto inval;
6287
6288 /* Check if the VMA got isolated after we found it */
6289 if (vma->detached) {
6290 vma_end_read(vma);
6291 count_vm_vma_lock_event(VMA_LOCK_MISS);
6292 /* The area was replaced with another one */
6293 goto retry;
6294 }
6295 /*
6296 * At this point, we have a stable reference to a VMA: The VMA is
6297 * locked and we know it hasn't already been isolated.
6298 * From here on, we can access the VMA without worrying about which
6299 * fields are accessible for RCU readers.
6300 */
6301
6302 /* Check since vm_start/vm_end might change before we lock the VMA */
6303 if (unlikely(address < vma->vm_start || address >= vma->vm_end))
6304 goto inval_end_read;
6305
6306 rcu_read_unlock();
6307 return vma;
6308
6309inval_end_read:
6310 vma_end_read(vma);
6311inval:
6312 rcu_read_unlock();
6313 count_vm_vma_lock_event(VMA_LOCK_ABORT);
6314 return NULL;
6315}
6316#endif /* CONFIG_PER_VMA_LOCK */
6317
6318#ifndef __PAGETABLE_P4D_FOLDED
6319/*
6320 * Allocate p4d page table.
6321 * We've already handled the fast-path in-line.
6322 */
6323int __p4d_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
6324{
6325 p4d_t *new = p4d_alloc_one(mm, address);
6326 if (!new)
6327 return -ENOMEM;
6328
6329 spin_lock(&mm->page_table_lock);
6330 if (pgd_present(*pgd)) { /* Another has populated it */
6331 p4d_free(mm, new);
6332 } else {
6333 smp_wmb(); /* See comment in pmd_install() */
6334 pgd_populate(mm, pgd, new);
6335 }
6336 spin_unlock(&mm->page_table_lock);
6337 return 0;
6338}
6339#endif /* __PAGETABLE_P4D_FOLDED */
6340
6341#ifndef __PAGETABLE_PUD_FOLDED
6342/*
6343 * Allocate page upper directory.
6344 * We've already handled the fast-path in-line.
6345 */
6346int __pud_alloc(struct mm_struct *mm, p4d_t *p4d, unsigned long address)
6347{
6348 pud_t *new = pud_alloc_one(mm, address);
6349 if (!new)
6350 return -ENOMEM;
6351
6352 spin_lock(&mm->page_table_lock);
6353 if (!p4d_present(*p4d)) {
6354 mm_inc_nr_puds(mm);
6355 smp_wmb(); /* See comment in pmd_install() */
6356 p4d_populate(mm, p4d, new);
6357 } else /* Another has populated it */
6358 pud_free(mm, new);
6359 spin_unlock(&mm->page_table_lock);
6360 return 0;
6361}
6362#endif /* __PAGETABLE_PUD_FOLDED */
6363
6364#ifndef __PAGETABLE_PMD_FOLDED
6365/*
6366 * Allocate page middle directory.
6367 * We've already handled the fast-path in-line.
6368 */
6369int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
6370{
6371 spinlock_t *ptl;
6372 pmd_t *new = pmd_alloc_one(mm, address);
6373 if (!new)
6374 return -ENOMEM;
6375
6376 ptl = pud_lock(mm, pud);
6377 if (!pud_present(*pud)) {
6378 mm_inc_nr_pmds(mm);
6379 smp_wmb(); /* See comment in pmd_install() */
6380 pud_populate(mm, pud, new);
6381 } else { /* Another has populated it */
6382 pmd_free(mm, new);
6383 }
6384 spin_unlock(ptl);
6385 return 0;
6386}
6387#endif /* __PAGETABLE_PMD_FOLDED */
6388
6389static inline void pfnmap_args_setup(struct follow_pfnmap_args *args,
6390 spinlock_t *lock, pte_t *ptep,
6391 pgprot_t pgprot, unsigned long pfn_base,
6392 unsigned long addr_mask, bool writable,
6393 bool special)
6394{
6395 args->lock = lock;
6396 args->ptep = ptep;
6397 args->pfn = pfn_base + ((args->address & ~addr_mask) >> PAGE_SHIFT);
6398 args->pgprot = pgprot;
6399 args->writable = writable;
6400 args->special = special;
6401}
6402
6403static inline void pfnmap_lockdep_assert(struct vm_area_struct *vma)
6404{
6405#ifdef CONFIG_LOCKDEP
6406 struct file *file = vma->vm_file;
6407 struct address_space *mapping = file ? file->f_mapping : NULL;
6408
6409 if (mapping)
6410 lockdep_assert(lockdep_is_held(&mapping->i_mmap_rwsem) ||
6411 lockdep_is_held(&vma->vm_mm->mmap_lock));
6412 else
6413 lockdep_assert(lockdep_is_held(&vma->vm_mm->mmap_lock));
6414#endif
6415}
6416
6417/**
6418 * follow_pfnmap_start() - Look up a pfn mapping at a user virtual address
6419 * @args: Pointer to struct @follow_pfnmap_args
6420 *
6421 * The caller needs to setup args->vma and args->address to point to the
6422 * virtual address as the target of such lookup. On a successful return,
6423 * the results will be put into other output fields.
6424 *
6425 * After the caller finished using the fields, the caller must invoke
6426 * another follow_pfnmap_end() to proper releases the locks and resources
6427 * of such look up request.
6428 *
6429 * During the start() and end() calls, the results in @args will be valid
6430 * as proper locks will be held. After the end() is called, all the fields
6431 * in @follow_pfnmap_args will be invalid to be further accessed. Further
6432 * use of such information after end() may require proper synchronizations
6433 * by the caller with page table updates, otherwise it can create a
6434 * security bug.
6435 *
6436 * If the PTE maps a refcounted page, callers are responsible to protect
6437 * against invalidation with MMU notifiers; otherwise access to the PFN at
6438 * a later point in time can trigger use-after-free.
6439 *
6440 * Only IO mappings and raw PFN mappings are allowed. The mmap semaphore
6441 * should be taken for read, and the mmap semaphore cannot be released
6442 * before the end() is invoked.
6443 *
6444 * This function must not be used to modify PTE content.
6445 *
6446 * Return: zero on success, negative otherwise.
6447 */
6448int follow_pfnmap_start(struct follow_pfnmap_args *args)
6449{
6450 struct vm_area_struct *vma = args->vma;
6451 unsigned long address = args->address;
6452 struct mm_struct *mm = vma->vm_mm;
6453 spinlock_t *lock;
6454 pgd_t *pgdp;
6455 p4d_t *p4dp, p4d;
6456 pud_t *pudp, pud;
6457 pmd_t *pmdp, pmd;
6458 pte_t *ptep, pte;
6459
6460 pfnmap_lockdep_assert(vma);
6461
6462 if (unlikely(address < vma->vm_start || address >= vma->vm_end))
6463 goto out;
6464
6465 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
6466 goto out;
6467retry:
6468 pgdp = pgd_offset(mm, address);
6469 if (pgd_none(*pgdp) || unlikely(pgd_bad(*pgdp)))
6470 goto out;
6471
6472 p4dp = p4d_offset(pgdp, address);
6473 p4d = READ_ONCE(*p4dp);
6474 if (p4d_none(p4d) || unlikely(p4d_bad(p4d)))
6475 goto out;
6476
6477 pudp = pud_offset(p4dp, address);
6478 pud = READ_ONCE(*pudp);
6479 if (pud_none(pud))
6480 goto out;
6481 if (pud_leaf(pud)) {
6482 lock = pud_lock(mm, pudp);
6483 if (!unlikely(pud_leaf(pud))) {
6484 spin_unlock(lock);
6485 goto retry;
6486 }
6487 pfnmap_args_setup(args, lock, NULL, pud_pgprot(pud),
6488 pud_pfn(pud), PUD_MASK, pud_write(pud),
6489 pud_special(pud));
6490 return 0;
6491 }
6492
6493 pmdp = pmd_offset(pudp, address);
6494 pmd = pmdp_get_lockless(pmdp);
6495 if (pmd_leaf(pmd)) {
6496 lock = pmd_lock(mm, pmdp);
6497 if (!unlikely(pmd_leaf(pmd))) {
6498 spin_unlock(lock);
6499 goto retry;
6500 }
6501 pfnmap_args_setup(args, lock, NULL, pmd_pgprot(pmd),
6502 pmd_pfn(pmd), PMD_MASK, pmd_write(pmd),
6503 pmd_special(pmd));
6504 return 0;
6505 }
6506
6507 ptep = pte_offset_map_lock(mm, pmdp, address, &lock);
6508 if (!ptep)
6509 goto out;
6510 pte = ptep_get(ptep);
6511 if (!pte_present(pte))
6512 goto unlock;
6513 pfnmap_args_setup(args, lock, ptep, pte_pgprot(pte),
6514 pte_pfn(pte), PAGE_MASK, pte_write(pte),
6515 pte_special(pte));
6516 return 0;
6517unlock:
6518 pte_unmap_unlock(ptep, lock);
6519out:
6520 return -EINVAL;
6521}
6522EXPORT_SYMBOL_GPL(follow_pfnmap_start);
6523
6524/**
6525 * follow_pfnmap_end(): End a follow_pfnmap_start() process
6526 * @args: Pointer to struct @follow_pfnmap_args
6527 *
6528 * Must be used in pair of follow_pfnmap_start(). See the start() function
6529 * above for more information.
6530 */
6531void follow_pfnmap_end(struct follow_pfnmap_args *args)
6532{
6533 if (args->lock)
6534 spin_unlock(args->lock);
6535 if (args->ptep)
6536 pte_unmap(args->ptep);
6537}
6538EXPORT_SYMBOL_GPL(follow_pfnmap_end);
6539
6540#ifdef CONFIG_HAVE_IOREMAP_PROT
6541/**
6542 * generic_access_phys - generic implementation for iomem mmap access
6543 * @vma: the vma to access
6544 * @addr: userspace address, not relative offset within @vma
6545 * @buf: buffer to read/write
6546 * @len: length of transfer
6547 * @write: set to FOLL_WRITE when writing, otherwise reading
6548 *
6549 * This is a generic implementation for &vm_operations_struct.access for an
6550 * iomem mapping. This callback is used by access_process_vm() when the @vma is
6551 * not page based.
6552 */
6553int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
6554 void *buf, int len, int write)
6555{
6556 resource_size_t phys_addr;
6557 unsigned long prot = 0;
6558 void __iomem *maddr;
6559 int offset = offset_in_page(addr);
6560 int ret = -EINVAL;
6561 bool writable;
6562 struct follow_pfnmap_args args = { .vma = vma, .address = addr };
6563
6564retry:
6565 if (follow_pfnmap_start(&args))
6566 return -EINVAL;
6567 prot = pgprot_val(args.pgprot);
6568 phys_addr = (resource_size_t)args.pfn << PAGE_SHIFT;
6569 writable = args.writable;
6570 follow_pfnmap_end(&args);
6571
6572 if ((write & FOLL_WRITE) && !writable)
6573 return -EINVAL;
6574
6575 maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
6576 if (!maddr)
6577 return -ENOMEM;
6578
6579 if (follow_pfnmap_start(&args))
6580 goto out_unmap;
6581
6582 if ((prot != pgprot_val(args.pgprot)) ||
6583 (phys_addr != (args.pfn << PAGE_SHIFT)) ||
6584 (writable != args.writable)) {
6585 follow_pfnmap_end(&args);
6586 iounmap(maddr);
6587 goto retry;
6588 }
6589
6590 if (write)
6591 memcpy_toio(maddr + offset, buf, len);
6592 else
6593 memcpy_fromio(buf, maddr + offset, len);
6594 ret = len;
6595 follow_pfnmap_end(&args);
6596out_unmap:
6597 iounmap(maddr);
6598
6599 return ret;
6600}
6601EXPORT_SYMBOL_GPL(generic_access_phys);
6602#endif
6603
6604/*
6605 * Access another process' address space as given in mm.
6606 */
6607static int __access_remote_vm(struct mm_struct *mm, unsigned long addr,
6608 void *buf, int len, unsigned int gup_flags)
6609{
6610 void *old_buf = buf;
6611 int write = gup_flags & FOLL_WRITE;
6612
6613 if (mmap_read_lock_killable(mm))
6614 return 0;
6615
6616 /* Untag the address before looking up the VMA */
6617 addr = untagged_addr_remote(mm, addr);
6618
6619 /* Avoid triggering the temporary warning in __get_user_pages */
6620 if (!vma_lookup(mm, addr) && !expand_stack(mm, addr))
6621 return 0;
6622
6623 /* ignore errors, just check how much was successfully transferred */
6624 while (len) {
6625 int bytes, offset;
6626 void *maddr;
6627 struct vm_area_struct *vma = NULL;
6628 struct page *page = get_user_page_vma_remote(mm, addr,
6629 gup_flags, &vma);
6630
6631 if (IS_ERR(page)) {
6632 /* We might need to expand the stack to access it */
6633 vma = vma_lookup(mm, addr);
6634 if (!vma) {
6635 vma = expand_stack(mm, addr);
6636
6637 /* mmap_lock was dropped on failure */
6638 if (!vma)
6639 return buf - old_buf;
6640
6641 /* Try again if stack expansion worked */
6642 continue;
6643 }
6644
6645 /*
6646 * Check if this is a VM_IO | VM_PFNMAP VMA, which
6647 * we can access using slightly different code.
6648 */
6649 bytes = 0;
6650#ifdef CONFIG_HAVE_IOREMAP_PROT
6651 if (vma->vm_ops && vma->vm_ops->access)
6652 bytes = vma->vm_ops->access(vma, addr, buf,
6653 len, write);
6654#endif
6655 if (bytes <= 0)
6656 break;
6657 } else {
6658 bytes = len;
6659 offset = addr & (PAGE_SIZE-1);
6660 if (bytes > PAGE_SIZE-offset)
6661 bytes = PAGE_SIZE-offset;
6662
6663 maddr = kmap_local_page(page);
6664 if (write) {
6665 copy_to_user_page(vma, page, addr,
6666 maddr + offset, buf, bytes);
6667 set_page_dirty_lock(page);
6668 } else {
6669 copy_from_user_page(vma, page, addr,
6670 buf, maddr + offset, bytes);
6671 }
6672 unmap_and_put_page(page, maddr);
6673 }
6674 len -= bytes;
6675 buf += bytes;
6676 addr += bytes;
6677 }
6678 mmap_read_unlock(mm);
6679
6680 return buf - old_buf;
6681}
6682
6683/**
6684 * access_remote_vm - access another process' address space
6685 * @mm: the mm_struct of the target address space
6686 * @addr: start address to access
6687 * @buf: source or destination buffer
6688 * @len: number of bytes to transfer
6689 * @gup_flags: flags modifying lookup behaviour
6690 *
6691 * The caller must hold a reference on @mm.
6692 *
6693 * Return: number of bytes copied from source to destination.
6694 */
6695int access_remote_vm(struct mm_struct *mm, unsigned long addr,
6696 void *buf, int len, unsigned int gup_flags)
6697{
6698 return __access_remote_vm(mm, addr, buf, len, gup_flags);
6699}
6700
6701/*
6702 * Access another process' address space.
6703 * Source/target buffer must be kernel space,
6704 * Do not walk the page table directly, use get_user_pages
6705 */
6706int access_process_vm(struct task_struct *tsk, unsigned long addr,
6707 void *buf, int len, unsigned int gup_flags)
6708{
6709 struct mm_struct *mm;
6710 int ret;
6711
6712 mm = get_task_mm(tsk);
6713 if (!mm)
6714 return 0;
6715
6716 ret = __access_remote_vm(mm, addr, buf, len, gup_flags);
6717
6718 mmput(mm);
6719
6720 return ret;
6721}
6722EXPORT_SYMBOL_GPL(access_process_vm);
6723
6724/*
6725 * Print the name of a VMA.
6726 */
6727void print_vma_addr(char *prefix, unsigned long ip)
6728{
6729 struct mm_struct *mm = current->mm;
6730 struct vm_area_struct *vma;
6731
6732 /*
6733 * we might be running from an atomic context so we cannot sleep
6734 */
6735 if (!mmap_read_trylock(mm))
6736 return;
6737
6738 vma = vma_lookup(mm, ip);
6739 if (vma && vma->vm_file) {
6740 struct file *f = vma->vm_file;
6741 ip -= vma->vm_start;
6742 ip += vma->vm_pgoff << PAGE_SHIFT;
6743 printk("%s%pD[%lx,%lx+%lx]", prefix, f, ip,
6744 vma->vm_start,
6745 vma->vm_end - vma->vm_start);
6746 }
6747 mmap_read_unlock(mm);
6748}
6749
6750#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
6751void __might_fault(const char *file, int line)
6752{
6753 if (pagefault_disabled())
6754 return;
6755 __might_sleep(file, line);
6756#if defined(CONFIG_DEBUG_ATOMIC_SLEEP)
6757 if (current->mm)
6758 might_lock_read(¤t->mm->mmap_lock);
6759#endif
6760}
6761EXPORT_SYMBOL(__might_fault);
6762#endif
6763
6764#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
6765/*
6766 * Process all subpages of the specified huge page with the specified
6767 * operation. The target subpage will be processed last to keep its
6768 * cache lines hot.
6769 */
6770static inline int process_huge_page(
6771 unsigned long addr_hint, unsigned int nr_pages,
6772 int (*process_subpage)(unsigned long addr, int idx, void *arg),
6773 void *arg)
6774{
6775 int i, n, base, l, ret;
6776 unsigned long addr = addr_hint &
6777 ~(((unsigned long)nr_pages << PAGE_SHIFT) - 1);
6778
6779 /* Process target subpage last to keep its cache lines hot */
6780 might_sleep();
6781 n = (addr_hint - addr) / PAGE_SIZE;
6782 if (2 * n <= nr_pages) {
6783 /* If target subpage in first half of huge page */
6784 base = 0;
6785 l = n;
6786 /* Process subpages at the end of huge page */
6787 for (i = nr_pages - 1; i >= 2 * n; i--) {
6788 cond_resched();
6789 ret = process_subpage(addr + i * PAGE_SIZE, i, arg);
6790 if (ret)
6791 return ret;
6792 }
6793 } else {
6794 /* If target subpage in second half of huge page */
6795 base = nr_pages - 2 * (nr_pages - n);
6796 l = nr_pages - n;
6797 /* Process subpages at the begin of huge page */
6798 for (i = 0; i < base; i++) {
6799 cond_resched();
6800 ret = process_subpage(addr + i * PAGE_SIZE, i, arg);
6801 if (ret)
6802 return ret;
6803 }
6804 }
6805 /*
6806 * Process remaining subpages in left-right-left-right pattern
6807 * towards the target subpage
6808 */
6809 for (i = 0; i < l; i++) {
6810 int left_idx = base + i;
6811 int right_idx = base + 2 * l - 1 - i;
6812
6813 cond_resched();
6814 ret = process_subpage(addr + left_idx * PAGE_SIZE, left_idx, arg);
6815 if (ret)
6816 return ret;
6817 cond_resched();
6818 ret = process_subpage(addr + right_idx * PAGE_SIZE, right_idx, arg);
6819 if (ret)
6820 return ret;
6821 }
6822 return 0;
6823}
6824
6825static void clear_gigantic_page(struct folio *folio, unsigned long addr_hint,
6826 unsigned int nr_pages)
6827{
6828 unsigned long addr = ALIGN_DOWN(addr_hint, folio_size(folio));
6829 int i;
6830
6831 might_sleep();
6832 for (i = 0; i < nr_pages; i++) {
6833 cond_resched();
6834 clear_user_highpage(folio_page(folio, i), addr + i * PAGE_SIZE);
6835 }
6836}
6837
6838static int clear_subpage(unsigned long addr, int idx, void *arg)
6839{
6840 struct folio *folio = arg;
6841
6842 clear_user_highpage(folio_page(folio, idx), addr);
6843 return 0;
6844}
6845
6846/**
6847 * folio_zero_user - Zero a folio which will be mapped to userspace.
6848 * @folio: The folio to zero.
6849 * @addr_hint: The address will be accessed or the base address if uncelar.
6850 */
6851void folio_zero_user(struct folio *folio, unsigned long addr_hint)
6852{
6853 unsigned int nr_pages = folio_nr_pages(folio);
6854
6855 if (unlikely(nr_pages > MAX_ORDER_NR_PAGES))
6856 clear_gigantic_page(folio, addr_hint, nr_pages);
6857 else
6858 process_huge_page(addr_hint, nr_pages, clear_subpage, folio);
6859}
6860
6861static int copy_user_gigantic_page(struct folio *dst, struct folio *src,
6862 unsigned long addr_hint,
6863 struct vm_area_struct *vma,
6864 unsigned int nr_pages)
6865{
6866 unsigned long addr = ALIGN_DOWN(addr_hint, folio_size(dst));
6867 struct page *dst_page;
6868 struct page *src_page;
6869 int i;
6870
6871 for (i = 0; i < nr_pages; i++) {
6872 dst_page = folio_page(dst, i);
6873 src_page = folio_page(src, i);
6874
6875 cond_resched();
6876 if (copy_mc_user_highpage(dst_page, src_page,
6877 addr + i*PAGE_SIZE, vma))
6878 return -EHWPOISON;
6879 }
6880 return 0;
6881}
6882
6883struct copy_subpage_arg {
6884 struct folio *dst;
6885 struct folio *src;
6886 struct vm_area_struct *vma;
6887};
6888
6889static int copy_subpage(unsigned long addr, int idx, void *arg)
6890{
6891 struct copy_subpage_arg *copy_arg = arg;
6892 struct page *dst = folio_page(copy_arg->dst, idx);
6893 struct page *src = folio_page(copy_arg->src, idx);
6894
6895 if (copy_mc_user_highpage(dst, src, addr, copy_arg->vma))
6896 return -EHWPOISON;
6897 return 0;
6898}
6899
6900int copy_user_large_folio(struct folio *dst, struct folio *src,
6901 unsigned long addr_hint, struct vm_area_struct *vma)
6902{
6903 unsigned int nr_pages = folio_nr_pages(dst);
6904 struct copy_subpage_arg arg = {
6905 .dst = dst,
6906 .src = src,
6907 .vma = vma,
6908 };
6909
6910 if (unlikely(nr_pages > MAX_ORDER_NR_PAGES))
6911 return copy_user_gigantic_page(dst, src, addr_hint, vma, nr_pages);
6912
6913 return process_huge_page(addr_hint, nr_pages, copy_subpage, &arg);
6914}
6915
6916long copy_folio_from_user(struct folio *dst_folio,
6917 const void __user *usr_src,
6918 bool allow_pagefault)
6919{
6920 void *kaddr;
6921 unsigned long i, rc = 0;
6922 unsigned int nr_pages = folio_nr_pages(dst_folio);
6923 unsigned long ret_val = nr_pages * PAGE_SIZE;
6924 struct page *subpage;
6925
6926 for (i = 0; i < nr_pages; i++) {
6927 subpage = folio_page(dst_folio, i);
6928 kaddr = kmap_local_page(subpage);
6929 if (!allow_pagefault)
6930 pagefault_disable();
6931 rc = copy_from_user(kaddr, usr_src + i * PAGE_SIZE, PAGE_SIZE);
6932 if (!allow_pagefault)
6933 pagefault_enable();
6934 kunmap_local(kaddr);
6935
6936 ret_val -= (PAGE_SIZE - rc);
6937 if (rc)
6938 break;
6939
6940 flush_dcache_page(subpage);
6941
6942 cond_resched();
6943 }
6944 return ret_val;
6945}
6946#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
6947
6948#if defined(CONFIG_SPLIT_PTE_PTLOCKS) && ALLOC_SPLIT_PTLOCKS
6949
6950static struct kmem_cache *page_ptl_cachep;
6951
6952void __init ptlock_cache_init(void)
6953{
6954 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
6955 SLAB_PANIC, NULL);
6956}
6957
6958bool ptlock_alloc(struct ptdesc *ptdesc)
6959{
6960 spinlock_t *ptl;
6961
6962 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
6963 if (!ptl)
6964 return false;
6965 ptdesc->ptl = ptl;
6966 return true;
6967}
6968
6969void ptlock_free(struct ptdesc *ptdesc)
6970{
6971 kmem_cache_free(page_ptl_cachep, ptdesc->ptl);
6972}
6973#endif
6974
6975void vma_pgtable_walk_begin(struct vm_area_struct *vma)
6976{
6977 if (is_vm_hugetlb_page(vma))
6978 hugetlb_vma_lock_read(vma);
6979}
6980
6981void vma_pgtable_walk_end(struct vm_area_struct *vma)
6982{
6983 if (is_vm_hugetlb_page(vma))
6984 hugetlb_vma_unlock_read(vma);
6985}