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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/*
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/hugetlb.h>
44#include <linux/mman.h>
45#include <linux/swap.h>
46#include <linux/highmem.h>
47#include <linux/pagemap.h>
48#include <linux/ksm.h>
49#include <linux/rmap.h>
50#include <linux/export.h>
51#include <linux/delayacct.h>
52#include <linux/init.h>
53#include <linux/writeback.h>
54#include <linux/memcontrol.h>
55#include <linux/mmu_notifier.h>
56#include <linux/kallsyms.h>
57#include <linux/swapops.h>
58#include <linux/elf.h>
59#include <linux/gfp.h>
60#include <linux/migrate.h>
61#include <linux/string.h>
62#include <linux/dma-debug.h>
63#include <linux/debugfs.h>
64
65#include <asm/io.h>
66#include <asm/pgalloc.h>
67#include <asm/uaccess.h>
68#include <asm/tlb.h>
69#include <asm/tlbflush.h>
70#include <asm/pgtable.h>
71
72#include "internal.h"
73
74#ifdef LAST_CPUPID_NOT_IN_PAGE_FLAGS
75#warning Unfortunate NUMA and NUMA Balancing config, growing page-frame for last_cpupid.
76#endif
77
78#ifndef CONFIG_NEED_MULTIPLE_NODES
79/* use the per-pgdat data instead for discontigmem - mbligh */
80unsigned long max_mapnr;
81struct page *mem_map;
82
83EXPORT_SYMBOL(max_mapnr);
84EXPORT_SYMBOL(mem_map);
85#endif
86
87/*
88 * A number of key systems in x86 including ioremap() rely on the assumption
89 * that high_memory defines the upper bound on direct map memory, then end
90 * of ZONE_NORMAL. Under CONFIG_DISCONTIG this means that max_low_pfn and
91 * highstart_pfn must be the same; there must be no gap between ZONE_NORMAL
92 * and ZONE_HIGHMEM.
93 */
94void * high_memory;
95
96EXPORT_SYMBOL(high_memory);
97
98/*
99 * Randomize the address space (stacks, mmaps, brk, etc.).
100 *
101 * ( When CONFIG_COMPAT_BRK=y we exclude brk from randomization,
102 * as ancient (libc5 based) binaries can segfault. )
103 */
104int randomize_va_space __read_mostly =
105#ifdef CONFIG_COMPAT_BRK
106 1;
107#else
108 2;
109#endif
110
111static int __init disable_randmaps(char *s)
112{
113 randomize_va_space = 0;
114 return 1;
115}
116__setup("norandmaps", disable_randmaps);
117
118unsigned long zero_pfn __read_mostly;
119unsigned long highest_memmap_pfn __read_mostly;
120
121/*
122 * CONFIG_MMU architectures set up ZERO_PAGE in their paging_init()
123 */
124static int __init init_zero_pfn(void)
125{
126 zero_pfn = page_to_pfn(ZERO_PAGE(0));
127 return 0;
128}
129core_initcall(init_zero_pfn);
130
131
132#if defined(SPLIT_RSS_COUNTING)
133
134void sync_mm_rss(struct mm_struct *mm)
135{
136 int i;
137
138 for (i = 0; i < NR_MM_COUNTERS; i++) {
139 if (current->rss_stat.count[i]) {
140 add_mm_counter(mm, i, current->rss_stat.count[i]);
141 current->rss_stat.count[i] = 0;
142 }
143 }
144 current->rss_stat.events = 0;
145}
146
147static void add_mm_counter_fast(struct mm_struct *mm, int member, int val)
148{
149 struct task_struct *task = current;
150
151 if (likely(task->mm == mm))
152 task->rss_stat.count[member] += val;
153 else
154 add_mm_counter(mm, member, val);
155}
156#define inc_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, 1)
157#define dec_mm_counter_fast(mm, member) add_mm_counter_fast(mm, member, -1)
158
159/* sync counter once per 64 page faults */
160#define TASK_RSS_EVENTS_THRESH (64)
161static void check_sync_rss_stat(struct task_struct *task)
162{
163 if (unlikely(task != current))
164 return;
165 if (unlikely(task->rss_stat.events++ > TASK_RSS_EVENTS_THRESH))
166 sync_mm_rss(task->mm);
167}
168#else /* SPLIT_RSS_COUNTING */
169
170#define inc_mm_counter_fast(mm, member) inc_mm_counter(mm, member)
171#define dec_mm_counter_fast(mm, member) dec_mm_counter(mm, member)
172
173static void check_sync_rss_stat(struct task_struct *task)
174{
175}
176
177#endif /* SPLIT_RSS_COUNTING */
178
179#ifdef HAVE_GENERIC_MMU_GATHER
180
181static int tlb_next_batch(struct mmu_gather *tlb)
182{
183 struct mmu_gather_batch *batch;
184
185 batch = tlb->active;
186 if (batch->next) {
187 tlb->active = batch->next;
188 return 1;
189 }
190
191 if (tlb->batch_count == MAX_GATHER_BATCH_COUNT)
192 return 0;
193
194 batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
195 if (!batch)
196 return 0;
197
198 tlb->batch_count++;
199 batch->next = NULL;
200 batch->nr = 0;
201 batch->max = MAX_GATHER_BATCH;
202
203 tlb->active->next = batch;
204 tlb->active = batch;
205
206 return 1;
207}
208
209/* tlb_gather_mmu
210 * Called to initialize an (on-stack) mmu_gather structure for page-table
211 * tear-down from @mm. The @fullmm argument is used when @mm is without
212 * users and we're going to destroy the full address space (exit/execve).
213 */
214void tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned long start, unsigned long end)
215{
216 tlb->mm = mm;
217
218 /* Is it from 0 to ~0? */
219 tlb->fullmm = !(start | (end+1));
220 tlb->need_flush_all = 0;
221 tlb->start = start;
222 tlb->end = end;
223 tlb->need_flush = 0;
224 tlb->local.next = NULL;
225 tlb->local.nr = 0;
226 tlb->local.max = ARRAY_SIZE(tlb->__pages);
227 tlb->active = &tlb->local;
228 tlb->batch_count = 0;
229
230#ifdef CONFIG_HAVE_RCU_TABLE_FREE
231 tlb->batch = NULL;
232#endif
233}
234
235static void tlb_flush_mmu_tlbonly(struct mmu_gather *tlb)
236{
237 tlb->need_flush = 0;
238 tlb_flush(tlb);
239#ifdef CONFIG_HAVE_RCU_TABLE_FREE
240 tlb_table_flush(tlb);
241#endif
242}
243
244static void tlb_flush_mmu_free(struct mmu_gather *tlb)
245{
246 struct mmu_gather_batch *batch;
247
248 for (batch = &tlb->local; batch; batch = batch->next) {
249 free_pages_and_swap_cache(batch->pages, batch->nr);
250 batch->nr = 0;
251 }
252 tlb->active = &tlb->local;
253}
254
255void tlb_flush_mmu(struct mmu_gather *tlb)
256{
257 if (!tlb->need_flush)
258 return;
259 tlb_flush_mmu_tlbonly(tlb);
260 tlb_flush_mmu_free(tlb);
261}
262
263/* tlb_finish_mmu
264 * Called at the end of the shootdown operation to free up any resources
265 * that were required.
266 */
267void tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
268{
269 struct mmu_gather_batch *batch, *next;
270
271 tlb_flush_mmu(tlb);
272
273 /* keep the page table cache within bounds */
274 check_pgt_cache();
275
276 for (batch = tlb->local.next; batch; batch = next) {
277 next = batch->next;
278 free_pages((unsigned long)batch, 0);
279 }
280 tlb->local.next = NULL;
281}
282
283/* __tlb_remove_page
284 * Must perform the equivalent to __free_pte(pte_get_and_clear(ptep)), while
285 * handling the additional races in SMP caused by other CPUs caching valid
286 * mappings in their TLBs. Returns the number of free page slots left.
287 * When out of page slots we must call tlb_flush_mmu().
288 */
289int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
290{
291 struct mmu_gather_batch *batch;
292
293 VM_BUG_ON(!tlb->need_flush);
294
295 batch = tlb->active;
296 batch->pages[batch->nr++] = page;
297 if (batch->nr == batch->max) {
298 if (!tlb_next_batch(tlb))
299 return 0;
300 batch = tlb->active;
301 }
302 VM_BUG_ON_PAGE(batch->nr > batch->max, page);
303
304 return batch->max - batch->nr;
305}
306
307#endif /* HAVE_GENERIC_MMU_GATHER */
308
309#ifdef CONFIG_HAVE_RCU_TABLE_FREE
310
311/*
312 * See the comment near struct mmu_table_batch.
313 */
314
315static void tlb_remove_table_smp_sync(void *arg)
316{
317 /* Simply deliver the interrupt */
318}
319
320static void tlb_remove_table_one(void *table)
321{
322 /*
323 * This isn't an RCU grace period and hence the page-tables cannot be
324 * assumed to be actually RCU-freed.
325 *
326 * It is however sufficient for software page-table walkers that rely on
327 * IRQ disabling. See the comment near struct mmu_table_batch.
328 */
329 smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
330 __tlb_remove_table(table);
331}
332
333static void tlb_remove_table_rcu(struct rcu_head *head)
334{
335 struct mmu_table_batch *batch;
336 int i;
337
338 batch = container_of(head, struct mmu_table_batch, rcu);
339
340 for (i = 0; i < batch->nr; i++)
341 __tlb_remove_table(batch->tables[i]);
342
343 free_page((unsigned long)batch);
344}
345
346void tlb_table_flush(struct mmu_gather *tlb)
347{
348 struct mmu_table_batch **batch = &tlb->batch;
349
350 if (*batch) {
351 call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
352 *batch = NULL;
353 }
354}
355
356void tlb_remove_table(struct mmu_gather *tlb, void *table)
357{
358 struct mmu_table_batch **batch = &tlb->batch;
359
360 tlb->need_flush = 1;
361
362 /*
363 * When there's less then two users of this mm there cannot be a
364 * concurrent page-table walk.
365 */
366 if (atomic_read(&tlb->mm->mm_users) < 2) {
367 __tlb_remove_table(table);
368 return;
369 }
370
371 if (*batch == NULL) {
372 *batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
373 if (*batch == NULL) {
374 tlb_remove_table_one(table);
375 return;
376 }
377 (*batch)->nr = 0;
378 }
379 (*batch)->tables[(*batch)->nr++] = table;
380 if ((*batch)->nr == MAX_TABLE_BATCH)
381 tlb_table_flush(tlb);
382}
383
384#endif /* CONFIG_HAVE_RCU_TABLE_FREE */
385
386/*
387 * Note: this doesn't free the actual pages themselves. That
388 * has been handled earlier when unmapping all the memory regions.
389 */
390static void free_pte_range(struct mmu_gather *tlb, pmd_t *pmd,
391 unsigned long addr)
392{
393 pgtable_t token = pmd_pgtable(*pmd);
394 pmd_clear(pmd);
395 pte_free_tlb(tlb, token, addr);
396 atomic_long_dec(&tlb->mm->nr_ptes);
397}
398
399static inline void free_pmd_range(struct mmu_gather *tlb, pud_t *pud,
400 unsigned long addr, unsigned long end,
401 unsigned long floor, unsigned long ceiling)
402{
403 pmd_t *pmd;
404 unsigned long next;
405 unsigned long start;
406
407 start = addr;
408 pmd = pmd_offset(pud, addr);
409 do {
410 next = pmd_addr_end(addr, end);
411 if (pmd_none_or_clear_bad(pmd))
412 continue;
413 free_pte_range(tlb, pmd, addr);
414 } while (pmd++, addr = next, addr != end);
415
416 start &= PUD_MASK;
417 if (start < floor)
418 return;
419 if (ceiling) {
420 ceiling &= PUD_MASK;
421 if (!ceiling)
422 return;
423 }
424 if (end - 1 > ceiling - 1)
425 return;
426
427 pmd = pmd_offset(pud, start);
428 pud_clear(pud);
429 pmd_free_tlb(tlb, pmd, start);
430}
431
432static inline void free_pud_range(struct mmu_gather *tlb, pgd_t *pgd,
433 unsigned long addr, unsigned long end,
434 unsigned long floor, unsigned long ceiling)
435{
436 pud_t *pud;
437 unsigned long next;
438 unsigned long start;
439
440 start = addr;
441 pud = pud_offset(pgd, addr);
442 do {
443 next = pud_addr_end(addr, end);
444 if (pud_none_or_clear_bad(pud))
445 continue;
446 free_pmd_range(tlb, pud, addr, next, floor, ceiling);
447 } while (pud++, addr = next, addr != end);
448
449 start &= PGDIR_MASK;
450 if (start < floor)
451 return;
452 if (ceiling) {
453 ceiling &= PGDIR_MASK;
454 if (!ceiling)
455 return;
456 }
457 if (end - 1 > ceiling - 1)
458 return;
459
460 pud = pud_offset(pgd, start);
461 pgd_clear(pgd);
462 pud_free_tlb(tlb, pud, start);
463}
464
465/*
466 * This function frees user-level page tables of a process.
467 */
468void free_pgd_range(struct mmu_gather *tlb,
469 unsigned long addr, unsigned long end,
470 unsigned long floor, unsigned long ceiling)
471{
472 pgd_t *pgd;
473 unsigned long next;
474
475 /*
476 * The next few lines have given us lots of grief...
477 *
478 * Why are we testing PMD* at this top level? Because often
479 * there will be no work to do at all, and we'd prefer not to
480 * go all the way down to the bottom just to discover that.
481 *
482 * Why all these "- 1"s? Because 0 represents both the bottom
483 * of the address space and the top of it (using -1 for the
484 * top wouldn't help much: the masks would do the wrong thing).
485 * The rule is that addr 0 and floor 0 refer to the bottom of
486 * the address space, but end 0 and ceiling 0 refer to the top
487 * Comparisons need to use "end - 1" and "ceiling - 1" (though
488 * that end 0 case should be mythical).
489 *
490 * Wherever addr is brought up or ceiling brought down, we must
491 * be careful to reject "the opposite 0" before it confuses the
492 * subsequent tests. But what about where end is brought down
493 * by PMD_SIZE below? no, end can't go down to 0 there.
494 *
495 * Whereas we round start (addr) and ceiling down, by different
496 * masks at different levels, in order to test whether a table
497 * now has no other vmas using it, so can be freed, we don't
498 * bother to round floor or end up - the tests don't need that.
499 */
500
501 addr &= PMD_MASK;
502 if (addr < floor) {
503 addr += PMD_SIZE;
504 if (!addr)
505 return;
506 }
507 if (ceiling) {
508 ceiling &= PMD_MASK;
509 if (!ceiling)
510 return;
511 }
512 if (end - 1 > ceiling - 1)
513 end -= PMD_SIZE;
514 if (addr > end - 1)
515 return;
516
517 pgd = pgd_offset(tlb->mm, addr);
518 do {
519 next = pgd_addr_end(addr, end);
520 if (pgd_none_or_clear_bad(pgd))
521 continue;
522 free_pud_range(tlb, pgd, addr, next, floor, ceiling);
523 } while (pgd++, addr = next, addr != end);
524}
525
526void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
527 unsigned long floor, unsigned long ceiling)
528{
529 while (vma) {
530 struct vm_area_struct *next = vma->vm_next;
531 unsigned long addr = vma->vm_start;
532
533 /*
534 * Hide vma from rmap and truncate_pagecache before freeing
535 * pgtables
536 */
537 unlink_anon_vmas(vma);
538 unlink_file_vma(vma);
539
540 if (is_vm_hugetlb_page(vma)) {
541 hugetlb_free_pgd_range(tlb, addr, vma->vm_end,
542 floor, next? next->vm_start: ceiling);
543 } else {
544 /*
545 * Optimization: gather nearby vmas into one call down
546 */
547 while (next && next->vm_start <= vma->vm_end + PMD_SIZE
548 && !is_vm_hugetlb_page(next)) {
549 vma = next;
550 next = vma->vm_next;
551 unlink_anon_vmas(vma);
552 unlink_file_vma(vma);
553 }
554 free_pgd_range(tlb, addr, vma->vm_end,
555 floor, next? next->vm_start: ceiling);
556 }
557 vma = next;
558 }
559}
560
561int __pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,
562 pmd_t *pmd, unsigned long address)
563{
564 spinlock_t *ptl;
565 pgtable_t new = pte_alloc_one(mm, address);
566 int wait_split_huge_page;
567 if (!new)
568 return -ENOMEM;
569
570 /*
571 * Ensure all pte setup (eg. pte page lock and page clearing) are
572 * visible before the pte is made visible to other CPUs by being
573 * put into page tables.
574 *
575 * The other side of the story is the pointer chasing in the page
576 * table walking code (when walking the page table without locking;
577 * ie. most of the time). Fortunately, these data accesses consist
578 * of a chain of data-dependent loads, meaning most CPUs (alpha
579 * being the notable exception) will already guarantee loads are
580 * seen in-order. See the alpha page table accessors for the
581 * smp_read_barrier_depends() barriers in page table walking code.
582 */
583 smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */
584
585 ptl = pmd_lock(mm, pmd);
586 wait_split_huge_page = 0;
587 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
588 atomic_long_inc(&mm->nr_ptes);
589 pmd_populate(mm, pmd, new);
590 new = NULL;
591 } else if (unlikely(pmd_trans_splitting(*pmd)))
592 wait_split_huge_page = 1;
593 spin_unlock(ptl);
594 if (new)
595 pte_free(mm, new);
596 if (wait_split_huge_page)
597 wait_split_huge_page(vma->anon_vma, pmd);
598 return 0;
599}
600
601int __pte_alloc_kernel(pmd_t *pmd, unsigned long address)
602{
603 pte_t *new = pte_alloc_one_kernel(&init_mm, address);
604 if (!new)
605 return -ENOMEM;
606
607 smp_wmb(); /* See comment in __pte_alloc */
608
609 spin_lock(&init_mm.page_table_lock);
610 if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
611 pmd_populate_kernel(&init_mm, pmd, new);
612 new = NULL;
613 } else
614 VM_BUG_ON(pmd_trans_splitting(*pmd));
615 spin_unlock(&init_mm.page_table_lock);
616 if (new)
617 pte_free_kernel(&init_mm, new);
618 return 0;
619}
620
621static inline void init_rss_vec(int *rss)
622{
623 memset(rss, 0, sizeof(int) * NR_MM_COUNTERS);
624}
625
626static inline void add_mm_rss_vec(struct mm_struct *mm, int *rss)
627{
628 int i;
629
630 if (current->mm == mm)
631 sync_mm_rss(mm);
632 for (i = 0; i < NR_MM_COUNTERS; i++)
633 if (rss[i])
634 add_mm_counter(mm, i, rss[i]);
635}
636
637/*
638 * This function is called to print an error when a bad pte
639 * is found. For example, we might have a PFN-mapped pte in
640 * a region that doesn't allow it.
641 *
642 * The calling function must still handle the error.
643 */
644static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
645 pte_t pte, struct page *page)
646{
647 pgd_t *pgd = pgd_offset(vma->vm_mm, addr);
648 pud_t *pud = pud_offset(pgd, addr);
649 pmd_t *pmd = pmd_offset(pud, addr);
650 struct address_space *mapping;
651 pgoff_t index;
652 static unsigned long resume;
653 static unsigned long nr_shown;
654 static unsigned long nr_unshown;
655
656 /*
657 * Allow a burst of 60 reports, then keep quiet for that minute;
658 * or allow a steady drip of one report per second.
659 */
660 if (nr_shown == 60) {
661 if (time_before(jiffies, resume)) {
662 nr_unshown++;
663 return;
664 }
665 if (nr_unshown) {
666 printk(KERN_ALERT
667 "BUG: Bad page map: %lu messages suppressed\n",
668 nr_unshown);
669 nr_unshown = 0;
670 }
671 nr_shown = 0;
672 }
673 if (nr_shown++ == 0)
674 resume = jiffies + 60 * HZ;
675
676 mapping = vma->vm_file ? vma->vm_file->f_mapping : NULL;
677 index = linear_page_index(vma, addr);
678
679 printk(KERN_ALERT
680 "BUG: Bad page map in process %s pte:%08llx pmd:%08llx\n",
681 current->comm,
682 (long long)pte_val(pte), (long long)pmd_val(*pmd));
683 if (page)
684 dump_page(page, "bad pte");
685 printk(KERN_ALERT
686 "addr:%p vm_flags:%08lx anon_vma:%p mapping:%p index:%lx\n",
687 (void *)addr, vma->vm_flags, vma->anon_vma, mapping, index);
688 /*
689 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
690 */
691 if (vma->vm_ops)
692 printk(KERN_ALERT "vma->vm_ops->fault: %pSR\n",
693 vma->vm_ops->fault);
694 if (vma->vm_file)
695 printk(KERN_ALERT "vma->vm_file->f_op->mmap: %pSR\n",
696 vma->vm_file->f_op->mmap);
697 dump_stack();
698 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
699}
700
701static inline bool is_cow_mapping(vm_flags_t flags)
702{
703 return (flags & (VM_SHARED | VM_MAYWRITE)) == VM_MAYWRITE;
704}
705
706/*
707 * vm_normal_page -- This function gets the "struct page" associated with a pte.
708 *
709 * "Special" mappings do not wish to be associated with a "struct page" (either
710 * it doesn't exist, or it exists but they don't want to touch it). In this
711 * case, NULL is returned here. "Normal" mappings do have a struct page.
712 *
713 * There are 2 broad cases. Firstly, an architecture may define a pte_special()
714 * pte bit, in which case this function is trivial. Secondly, an architecture
715 * may not have a spare pte bit, which requires a more complicated scheme,
716 * described below.
717 *
718 * A raw VM_PFNMAP mapping (ie. one that is not COWed) is always considered a
719 * special mapping (even if there are underlying and valid "struct pages").
720 * COWed pages of a VM_PFNMAP are always normal.
721 *
722 * The way we recognize COWed pages within VM_PFNMAP mappings is through the
723 * rules set up by "remap_pfn_range()": the vma will have the VM_PFNMAP bit
724 * set, and the vm_pgoff will point to the first PFN mapped: thus every special
725 * mapping will always honor the rule
726 *
727 * pfn_of_page == vma->vm_pgoff + ((addr - vma->vm_start) >> PAGE_SHIFT)
728 *
729 * And for normal mappings this is false.
730 *
731 * This restricts such mappings to be a linear translation from virtual address
732 * to pfn. To get around this restriction, we allow arbitrary mappings so long
733 * as the vma is not a COW mapping; in that case, we know that all ptes are
734 * special (because none can have been COWed).
735 *
736 *
737 * In order to support COW of arbitrary special mappings, we have VM_MIXEDMAP.
738 *
739 * VM_MIXEDMAP mappings can likewise contain memory with or without "struct
740 * page" backing, however the difference is that _all_ pages with a struct
741 * page (that is, those where pfn_valid is true) are refcounted and considered
742 * normal pages by the VM. The disadvantage is that pages are refcounted
743 * (which can be slower and simply not an option for some PFNMAP users). The
744 * advantage is that we don't have to follow the strict linearity rule of
745 * PFNMAP mappings in order to support COWable mappings.
746 *
747 */
748#ifdef __HAVE_ARCH_PTE_SPECIAL
749# define HAVE_PTE_SPECIAL 1
750#else
751# define HAVE_PTE_SPECIAL 0
752#endif
753struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
754 pte_t pte)
755{
756 unsigned long pfn = pte_pfn(pte);
757
758 if (HAVE_PTE_SPECIAL) {
759 if (likely(!pte_special(pte)))
760 goto check_pfn;
761 if (vma->vm_flags & (VM_PFNMAP | VM_MIXEDMAP))
762 return NULL;
763 if (!is_zero_pfn(pfn))
764 print_bad_pte(vma, addr, pte, NULL);
765 return NULL;
766 }
767
768 /* !HAVE_PTE_SPECIAL case follows: */
769
770 if (unlikely(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP))) {
771 if (vma->vm_flags & VM_MIXEDMAP) {
772 if (!pfn_valid(pfn))
773 return NULL;
774 goto out;
775 } else {
776 unsigned long off;
777 off = (addr - vma->vm_start) >> PAGE_SHIFT;
778 if (pfn == vma->vm_pgoff + off)
779 return NULL;
780 if (!is_cow_mapping(vma->vm_flags))
781 return NULL;
782 }
783 }
784
785 if (is_zero_pfn(pfn))
786 return NULL;
787check_pfn:
788 if (unlikely(pfn > highest_memmap_pfn)) {
789 print_bad_pte(vma, addr, pte, NULL);
790 return NULL;
791 }
792
793 /*
794 * NOTE! We still have PageReserved() pages in the page tables.
795 * eg. VDSO mappings can cause them to exist.
796 */
797out:
798 return pfn_to_page(pfn);
799}
800
801/*
802 * copy one vm_area from one task to the other. Assumes the page tables
803 * already present in the new task to be cleared in the whole range
804 * covered by this vma.
805 */
806
807static inline unsigned long
808copy_one_pte(struct mm_struct *dst_mm, struct mm_struct *src_mm,
809 pte_t *dst_pte, pte_t *src_pte, struct vm_area_struct *vma,
810 unsigned long addr, int *rss)
811{
812 unsigned long vm_flags = vma->vm_flags;
813 pte_t pte = *src_pte;
814 struct page *page;
815
816 /* pte contains position in swap or file, so copy. */
817 if (unlikely(!pte_present(pte))) {
818 if (!pte_file(pte)) {
819 swp_entry_t entry = pte_to_swp_entry(pte);
820
821 if (swap_duplicate(entry) < 0)
822 return entry.val;
823
824 /* make sure dst_mm is on swapoff's mmlist. */
825 if (unlikely(list_empty(&dst_mm->mmlist))) {
826 spin_lock(&mmlist_lock);
827 if (list_empty(&dst_mm->mmlist))
828 list_add(&dst_mm->mmlist,
829 &src_mm->mmlist);
830 spin_unlock(&mmlist_lock);
831 }
832 if (likely(!non_swap_entry(entry)))
833 rss[MM_SWAPENTS]++;
834 else if (is_migration_entry(entry)) {
835 page = migration_entry_to_page(entry);
836
837 if (PageAnon(page))
838 rss[MM_ANONPAGES]++;
839 else
840 rss[MM_FILEPAGES]++;
841
842 if (is_write_migration_entry(entry) &&
843 is_cow_mapping(vm_flags)) {
844 /*
845 * COW mappings require pages in both
846 * parent and child to be set to read.
847 */
848 make_migration_entry_read(&entry);
849 pte = swp_entry_to_pte(entry);
850 if (pte_swp_soft_dirty(*src_pte))
851 pte = pte_swp_mksoft_dirty(pte);
852 set_pte_at(src_mm, addr, src_pte, pte);
853 }
854 }
855 }
856 goto out_set_pte;
857 }
858
859 /*
860 * If it's a COW mapping, write protect it both
861 * in the parent and the child
862 */
863 if (is_cow_mapping(vm_flags)) {
864 ptep_set_wrprotect(src_mm, addr, src_pte);
865 pte = pte_wrprotect(pte);
866 }
867
868 /*
869 * If it's a shared mapping, mark it clean in
870 * the child
871 */
872 if (vm_flags & VM_SHARED)
873 pte = pte_mkclean(pte);
874 pte = pte_mkold(pte);
875
876 page = vm_normal_page(vma, addr, pte);
877 if (page) {
878 get_page(page);
879 page_dup_rmap(page);
880 if (PageAnon(page))
881 rss[MM_ANONPAGES]++;
882 else
883 rss[MM_FILEPAGES]++;
884 }
885
886out_set_pte:
887 set_pte_at(dst_mm, addr, dst_pte, pte);
888 return 0;
889}
890
891int copy_pte_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
892 pmd_t *dst_pmd, pmd_t *src_pmd, struct vm_area_struct *vma,
893 unsigned long addr, unsigned long end)
894{
895 pte_t *orig_src_pte, *orig_dst_pte;
896 pte_t *src_pte, *dst_pte;
897 spinlock_t *src_ptl, *dst_ptl;
898 int progress = 0;
899 int rss[NR_MM_COUNTERS];
900 swp_entry_t entry = (swp_entry_t){0};
901
902again:
903 init_rss_vec(rss);
904
905 dst_pte = pte_alloc_map_lock(dst_mm, dst_pmd, addr, &dst_ptl);
906 if (!dst_pte)
907 return -ENOMEM;
908 src_pte = pte_offset_map(src_pmd, addr);
909 src_ptl = pte_lockptr(src_mm, src_pmd);
910 spin_lock_nested(src_ptl, SINGLE_DEPTH_NESTING);
911 orig_src_pte = src_pte;
912 orig_dst_pte = dst_pte;
913 arch_enter_lazy_mmu_mode();
914
915 do {
916 /*
917 * We are holding two locks at this point - either of them
918 * could generate latencies in another task on another CPU.
919 */
920 if (progress >= 32) {
921 progress = 0;
922 if (need_resched() ||
923 spin_needbreak(src_ptl) || spin_needbreak(dst_ptl))
924 break;
925 }
926 if (pte_none(*src_pte)) {
927 progress++;
928 continue;
929 }
930 entry.val = copy_one_pte(dst_mm, src_mm, dst_pte, src_pte,
931 vma, addr, rss);
932 if (entry.val)
933 break;
934 progress += 8;
935 } while (dst_pte++, src_pte++, addr += PAGE_SIZE, addr != end);
936
937 arch_leave_lazy_mmu_mode();
938 spin_unlock(src_ptl);
939 pte_unmap(orig_src_pte);
940 add_mm_rss_vec(dst_mm, rss);
941 pte_unmap_unlock(orig_dst_pte, dst_ptl);
942 cond_resched();
943
944 if (entry.val) {
945 if (add_swap_count_continuation(entry, GFP_KERNEL) < 0)
946 return -ENOMEM;
947 progress = 0;
948 }
949 if (addr != end)
950 goto again;
951 return 0;
952}
953
954static inline int copy_pmd_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
955 pud_t *dst_pud, pud_t *src_pud, struct vm_area_struct *vma,
956 unsigned long addr, unsigned long end)
957{
958 pmd_t *src_pmd, *dst_pmd;
959 unsigned long next;
960
961 dst_pmd = pmd_alloc(dst_mm, dst_pud, addr);
962 if (!dst_pmd)
963 return -ENOMEM;
964 src_pmd = pmd_offset(src_pud, addr);
965 do {
966 next = pmd_addr_end(addr, end);
967 if (pmd_trans_huge(*src_pmd)) {
968 int err;
969 VM_BUG_ON(next-addr != HPAGE_PMD_SIZE);
970 err = copy_huge_pmd(dst_mm, src_mm,
971 dst_pmd, src_pmd, addr, vma);
972 if (err == -ENOMEM)
973 return -ENOMEM;
974 if (!err)
975 continue;
976 /* fall through */
977 }
978 if (pmd_none_or_clear_bad(src_pmd))
979 continue;
980 if (copy_pte_range(dst_mm, src_mm, dst_pmd, src_pmd,
981 vma, addr, next))
982 return -ENOMEM;
983 } while (dst_pmd++, src_pmd++, addr = next, addr != end);
984 return 0;
985}
986
987static inline int copy_pud_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
988 pgd_t *dst_pgd, pgd_t *src_pgd, struct vm_area_struct *vma,
989 unsigned long addr, unsigned long end)
990{
991 pud_t *src_pud, *dst_pud;
992 unsigned long next;
993
994 dst_pud = pud_alloc(dst_mm, dst_pgd, addr);
995 if (!dst_pud)
996 return -ENOMEM;
997 src_pud = pud_offset(src_pgd, addr);
998 do {
999 next = pud_addr_end(addr, end);
1000 if (pud_none_or_clear_bad(src_pud))
1001 continue;
1002 if (copy_pmd_range(dst_mm, src_mm, dst_pud, src_pud,
1003 vma, addr, next))
1004 return -ENOMEM;
1005 } while (dst_pud++, src_pud++, addr = next, addr != end);
1006 return 0;
1007}
1008
1009int copy_page_range(struct mm_struct *dst_mm, struct mm_struct *src_mm,
1010 struct vm_area_struct *vma)
1011{
1012 pgd_t *src_pgd, *dst_pgd;
1013 unsigned long next;
1014 unsigned long addr = vma->vm_start;
1015 unsigned long end = vma->vm_end;
1016 unsigned long mmun_start; /* For mmu_notifiers */
1017 unsigned long mmun_end; /* For mmu_notifiers */
1018 bool is_cow;
1019 int ret;
1020
1021 /*
1022 * Don't copy ptes where a page fault will fill them correctly.
1023 * Fork becomes much lighter when there are big shared or private
1024 * readonly mappings. The tradeoff is that copy_page_range is more
1025 * efficient than faulting.
1026 */
1027 if (!(vma->vm_flags & (VM_HUGETLB | VM_NONLINEAR |
1028 VM_PFNMAP | VM_MIXEDMAP))) {
1029 if (!vma->anon_vma)
1030 return 0;
1031 }
1032
1033 if (is_vm_hugetlb_page(vma))
1034 return copy_hugetlb_page_range(dst_mm, src_mm, vma);
1035
1036 if (unlikely(vma->vm_flags & VM_PFNMAP)) {
1037 /*
1038 * We do not free on error cases below as remove_vma
1039 * gets called on error from higher level routine
1040 */
1041 ret = track_pfn_copy(vma);
1042 if (ret)
1043 return ret;
1044 }
1045
1046 /*
1047 * We need to invalidate the secondary MMU mappings only when
1048 * there could be a permission downgrade on the ptes of the
1049 * parent mm. And a permission downgrade will only happen if
1050 * is_cow_mapping() returns true.
1051 */
1052 is_cow = is_cow_mapping(vma->vm_flags);
1053 mmun_start = addr;
1054 mmun_end = end;
1055 if (is_cow)
1056 mmu_notifier_invalidate_range_start(src_mm, mmun_start,
1057 mmun_end);
1058
1059 ret = 0;
1060 dst_pgd = pgd_offset(dst_mm, addr);
1061 src_pgd = pgd_offset(src_mm, addr);
1062 do {
1063 next = pgd_addr_end(addr, end);
1064 if (pgd_none_or_clear_bad(src_pgd))
1065 continue;
1066 if (unlikely(copy_pud_range(dst_mm, src_mm, dst_pgd, src_pgd,
1067 vma, addr, next))) {
1068 ret = -ENOMEM;
1069 break;
1070 }
1071 } while (dst_pgd++, src_pgd++, addr = next, addr != end);
1072
1073 if (is_cow)
1074 mmu_notifier_invalidate_range_end(src_mm, mmun_start, mmun_end);
1075 return ret;
1076}
1077
1078static unsigned long zap_pte_range(struct mmu_gather *tlb,
1079 struct vm_area_struct *vma, pmd_t *pmd,
1080 unsigned long addr, unsigned long end,
1081 struct zap_details *details)
1082{
1083 struct mm_struct *mm = tlb->mm;
1084 int force_flush = 0;
1085 int rss[NR_MM_COUNTERS];
1086 spinlock_t *ptl;
1087 pte_t *start_pte;
1088 pte_t *pte;
1089
1090again:
1091 init_rss_vec(rss);
1092 start_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
1093 pte = start_pte;
1094 arch_enter_lazy_mmu_mode();
1095 do {
1096 pte_t ptent = *pte;
1097 if (pte_none(ptent)) {
1098 continue;
1099 }
1100
1101 if (pte_present(ptent)) {
1102 struct page *page;
1103
1104 page = vm_normal_page(vma, addr, ptent);
1105 if (unlikely(details) && page) {
1106 /*
1107 * unmap_shared_mapping_pages() wants to
1108 * invalidate cache without truncating:
1109 * unmap shared but keep private pages.
1110 */
1111 if (details->check_mapping &&
1112 details->check_mapping != page->mapping)
1113 continue;
1114 /*
1115 * Each page->index must be checked when
1116 * invalidating or truncating nonlinear.
1117 */
1118 if (details->nonlinear_vma &&
1119 (page->index < details->first_index ||
1120 page->index > details->last_index))
1121 continue;
1122 }
1123 ptent = ptep_get_and_clear_full(mm, addr, pte,
1124 tlb->fullmm);
1125 tlb_remove_tlb_entry(tlb, pte, addr);
1126 if (unlikely(!page))
1127 continue;
1128 if (unlikely(details) && details->nonlinear_vma
1129 && linear_page_index(details->nonlinear_vma,
1130 addr) != page->index) {
1131 pte_t ptfile = pgoff_to_pte(page->index);
1132 if (pte_soft_dirty(ptent))
1133 pte_file_mksoft_dirty(ptfile);
1134 set_pte_at(mm, addr, pte, ptfile);
1135 }
1136 if (PageAnon(page))
1137 rss[MM_ANONPAGES]--;
1138 else {
1139 if (pte_dirty(ptent)) {
1140 force_flush = 1;
1141 set_page_dirty(page);
1142 }
1143 if (pte_young(ptent) &&
1144 likely(!(vma->vm_flags & VM_SEQ_READ)))
1145 mark_page_accessed(page);
1146 rss[MM_FILEPAGES]--;
1147 }
1148 page_remove_rmap(page);
1149 if (unlikely(page_mapcount(page) < 0))
1150 print_bad_pte(vma, addr, ptent, page);
1151 if (unlikely(!__tlb_remove_page(tlb, page))) {
1152 force_flush = 1;
1153 break;
1154 }
1155 continue;
1156 }
1157 /*
1158 * If details->check_mapping, we leave swap entries;
1159 * if details->nonlinear_vma, we leave file entries.
1160 */
1161 if (unlikely(details))
1162 continue;
1163 if (pte_file(ptent)) {
1164 if (unlikely(!(vma->vm_flags & VM_NONLINEAR)))
1165 print_bad_pte(vma, addr, ptent, NULL);
1166 } else {
1167 swp_entry_t entry = pte_to_swp_entry(ptent);
1168
1169 if (!non_swap_entry(entry))
1170 rss[MM_SWAPENTS]--;
1171 else if (is_migration_entry(entry)) {
1172 struct page *page;
1173
1174 page = migration_entry_to_page(entry);
1175
1176 if (PageAnon(page))
1177 rss[MM_ANONPAGES]--;
1178 else
1179 rss[MM_FILEPAGES]--;
1180 }
1181 if (unlikely(!free_swap_and_cache(entry)))
1182 print_bad_pte(vma, addr, ptent, NULL);
1183 }
1184 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
1185 } while (pte++, addr += PAGE_SIZE, addr != end);
1186
1187 add_mm_rss_vec(mm, rss);
1188 arch_leave_lazy_mmu_mode();
1189
1190 /* Do the actual TLB flush before dropping ptl */
1191 if (force_flush) {
1192 unsigned long old_end;
1193
1194 /*
1195 * Flush the TLB just for the previous segment,
1196 * then update the range to be the remaining
1197 * TLB range.
1198 */
1199 old_end = tlb->end;
1200 tlb->end = addr;
1201 tlb_flush_mmu_tlbonly(tlb);
1202 tlb->start = addr;
1203 tlb->end = old_end;
1204 }
1205 pte_unmap_unlock(start_pte, ptl);
1206
1207 /*
1208 * If we forced a TLB flush (either due to running out of
1209 * batch buffers or because we needed to flush dirty TLB
1210 * entries before releasing the ptl), free the batched
1211 * memory too. Restart if we didn't do everything.
1212 */
1213 if (force_flush) {
1214 force_flush = 0;
1215 tlb_flush_mmu_free(tlb);
1216
1217 if (addr != end)
1218 goto again;
1219 }
1220
1221 return addr;
1222}
1223
1224static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
1225 struct vm_area_struct *vma, pud_t *pud,
1226 unsigned long addr, unsigned long end,
1227 struct zap_details *details)
1228{
1229 pmd_t *pmd;
1230 unsigned long next;
1231
1232 pmd = pmd_offset(pud, addr);
1233 do {
1234 next = pmd_addr_end(addr, end);
1235 if (pmd_trans_huge(*pmd)) {
1236 if (next - addr != HPAGE_PMD_SIZE) {
1237#ifdef CONFIG_DEBUG_VM
1238 if (!rwsem_is_locked(&tlb->mm->mmap_sem)) {
1239 pr_err("%s: mmap_sem is unlocked! addr=0x%lx end=0x%lx vma->vm_start=0x%lx vma->vm_end=0x%lx\n",
1240 __func__, addr, end,
1241 vma->vm_start,
1242 vma->vm_end);
1243 BUG();
1244 }
1245#endif
1246 split_huge_page_pmd(vma, addr, pmd);
1247 } else if (zap_huge_pmd(tlb, vma, pmd, addr))
1248 goto next;
1249 /* fall through */
1250 }
1251 /*
1252 * Here there can be other concurrent MADV_DONTNEED or
1253 * trans huge page faults running, and if the pmd is
1254 * none or trans huge it can change under us. This is
1255 * because MADV_DONTNEED holds the mmap_sem in read
1256 * mode.
1257 */
1258 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
1259 goto next;
1260 next = zap_pte_range(tlb, vma, pmd, addr, next, details);
1261next:
1262 cond_resched();
1263 } while (pmd++, addr = next, addr != end);
1264
1265 return addr;
1266}
1267
1268static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
1269 struct vm_area_struct *vma, pgd_t *pgd,
1270 unsigned long addr, unsigned long end,
1271 struct zap_details *details)
1272{
1273 pud_t *pud;
1274 unsigned long next;
1275
1276 pud = pud_offset(pgd, addr);
1277 do {
1278 next = pud_addr_end(addr, end);
1279 if (pud_none_or_clear_bad(pud))
1280 continue;
1281 next = zap_pmd_range(tlb, vma, pud, addr, next, details);
1282 } while (pud++, addr = next, addr != end);
1283
1284 return addr;
1285}
1286
1287static void unmap_page_range(struct mmu_gather *tlb,
1288 struct vm_area_struct *vma,
1289 unsigned long addr, unsigned long end,
1290 struct zap_details *details)
1291{
1292 pgd_t *pgd;
1293 unsigned long next;
1294
1295 if (details && !details->check_mapping && !details->nonlinear_vma)
1296 details = NULL;
1297
1298 BUG_ON(addr >= end);
1299 mem_cgroup_uncharge_start();
1300 tlb_start_vma(tlb, vma);
1301 pgd = pgd_offset(vma->vm_mm, addr);
1302 do {
1303 next = pgd_addr_end(addr, end);
1304 if (pgd_none_or_clear_bad(pgd))
1305 continue;
1306 next = zap_pud_range(tlb, vma, pgd, addr, next, details);
1307 } while (pgd++, addr = next, addr != end);
1308 tlb_end_vma(tlb, vma);
1309 mem_cgroup_uncharge_end();
1310}
1311
1312
1313static void unmap_single_vma(struct mmu_gather *tlb,
1314 struct vm_area_struct *vma, unsigned long start_addr,
1315 unsigned long end_addr,
1316 struct zap_details *details)
1317{
1318 unsigned long start = max(vma->vm_start, start_addr);
1319 unsigned long end;
1320
1321 if (start >= vma->vm_end)
1322 return;
1323 end = min(vma->vm_end, end_addr);
1324 if (end <= vma->vm_start)
1325 return;
1326
1327 if (vma->vm_file)
1328 uprobe_munmap(vma, start, end);
1329
1330 if (unlikely(vma->vm_flags & VM_PFNMAP))
1331 untrack_pfn(vma, 0, 0);
1332
1333 if (start != end) {
1334 if (unlikely(is_vm_hugetlb_page(vma))) {
1335 /*
1336 * It is undesirable to test vma->vm_file as it
1337 * should be non-null for valid hugetlb area.
1338 * However, vm_file will be NULL in the error
1339 * cleanup path of mmap_region. When
1340 * hugetlbfs ->mmap method fails,
1341 * mmap_region() nullifies vma->vm_file
1342 * before calling this function to clean up.
1343 * Since no pte has actually been setup, it is
1344 * safe to do nothing in this case.
1345 */
1346 if (vma->vm_file) {
1347 mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
1348 __unmap_hugepage_range_final(tlb, vma, start, end, NULL);
1349 mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
1350 }
1351 } else
1352 unmap_page_range(tlb, vma, start, end, details);
1353 }
1354}
1355
1356/**
1357 * unmap_vmas - unmap a range of memory covered by a list of vma's
1358 * @tlb: address of the caller's struct mmu_gather
1359 * @vma: the starting vma
1360 * @start_addr: virtual address at which to start unmapping
1361 * @end_addr: virtual address at which to end unmapping
1362 *
1363 * Unmap all pages in the vma list.
1364 *
1365 * Only addresses between `start' and `end' will be unmapped.
1366 *
1367 * The VMA list must be sorted in ascending virtual address order.
1368 *
1369 * unmap_vmas() assumes that the caller will flush the whole unmapped address
1370 * range after unmap_vmas() returns. So the only responsibility here is to
1371 * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
1372 * drops the lock and schedules.
1373 */
1374void unmap_vmas(struct mmu_gather *tlb,
1375 struct vm_area_struct *vma, unsigned long start_addr,
1376 unsigned long end_addr)
1377{
1378 struct mm_struct *mm = vma->vm_mm;
1379
1380 mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
1381 for ( ; vma && vma->vm_start < end_addr; vma = vma->vm_next)
1382 unmap_single_vma(tlb, vma, start_addr, end_addr, NULL);
1383 mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
1384}
1385
1386/**
1387 * zap_page_range - remove user pages in a given range
1388 * @vma: vm_area_struct holding the applicable pages
1389 * @start: starting address of pages to zap
1390 * @size: number of bytes to zap
1391 * @details: details of nonlinear truncation or shared cache invalidation
1392 *
1393 * Caller must protect the VMA list
1394 */
1395void zap_page_range(struct vm_area_struct *vma, unsigned long start,
1396 unsigned long size, struct zap_details *details)
1397{
1398 struct mm_struct *mm = vma->vm_mm;
1399 struct mmu_gather tlb;
1400 unsigned long end = start + size;
1401
1402 lru_add_drain();
1403 tlb_gather_mmu(&tlb, mm, start, end);
1404 update_hiwater_rss(mm);
1405 mmu_notifier_invalidate_range_start(mm, start, end);
1406 for ( ; vma && vma->vm_start < end; vma = vma->vm_next)
1407 unmap_single_vma(&tlb, vma, start, end, details);
1408 mmu_notifier_invalidate_range_end(mm, start, end);
1409 tlb_finish_mmu(&tlb, start, end);
1410}
1411
1412/**
1413 * zap_page_range_single - remove user pages in a given range
1414 * @vma: vm_area_struct holding the applicable pages
1415 * @address: starting address of pages to zap
1416 * @size: number of bytes to zap
1417 * @details: details of nonlinear truncation or shared cache invalidation
1418 *
1419 * The range must fit into one VMA.
1420 */
1421static void zap_page_range_single(struct vm_area_struct *vma, unsigned long address,
1422 unsigned long size, struct zap_details *details)
1423{
1424 struct mm_struct *mm = vma->vm_mm;
1425 struct mmu_gather tlb;
1426 unsigned long end = address + size;
1427
1428 lru_add_drain();
1429 tlb_gather_mmu(&tlb, mm, address, end);
1430 update_hiwater_rss(mm);
1431 mmu_notifier_invalidate_range_start(mm, address, end);
1432 unmap_single_vma(&tlb, vma, address, end, details);
1433 mmu_notifier_invalidate_range_end(mm, address, end);
1434 tlb_finish_mmu(&tlb, address, end);
1435}
1436
1437/**
1438 * zap_vma_ptes - remove ptes mapping the vma
1439 * @vma: vm_area_struct holding ptes to be zapped
1440 * @address: starting address of pages to zap
1441 * @size: number of bytes to zap
1442 *
1443 * This function only unmaps ptes assigned to VM_PFNMAP vmas.
1444 *
1445 * The entire address range must be fully contained within the vma.
1446 *
1447 * Returns 0 if successful.
1448 */
1449int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
1450 unsigned long size)
1451{
1452 if (address < vma->vm_start || address + size > vma->vm_end ||
1453 !(vma->vm_flags & VM_PFNMAP))
1454 return -1;
1455 zap_page_range_single(vma, address, size, NULL);
1456 return 0;
1457}
1458EXPORT_SYMBOL_GPL(zap_vma_ptes);
1459
1460/**
1461 * follow_page_mask - look up a page descriptor from a user-virtual address
1462 * @vma: vm_area_struct mapping @address
1463 * @address: virtual address to look up
1464 * @flags: flags modifying lookup behaviour
1465 * @page_mask: on output, *page_mask is set according to the size of the page
1466 *
1467 * @flags can have FOLL_ flags set, defined in <linux/mm.h>
1468 *
1469 * Returns the mapped (struct page *), %NULL if no mapping exists, or
1470 * an error pointer if there is a mapping to something not represented
1471 * by a page descriptor (see also vm_normal_page()).
1472 */
1473struct page *follow_page_mask(struct vm_area_struct *vma,
1474 unsigned long address, unsigned int flags,
1475 unsigned int *page_mask)
1476{
1477 pgd_t *pgd;
1478 pud_t *pud;
1479 pmd_t *pmd;
1480 pte_t *ptep, pte;
1481 spinlock_t *ptl;
1482 struct page *page;
1483 struct mm_struct *mm = vma->vm_mm;
1484
1485 *page_mask = 0;
1486
1487 page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
1488 if (!IS_ERR(page)) {
1489 BUG_ON(flags & FOLL_GET);
1490 goto out;
1491 }
1492
1493 page = NULL;
1494 pgd = pgd_offset(mm, address);
1495 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
1496 goto no_page_table;
1497
1498 pud = pud_offset(pgd, address);
1499 if (pud_none(*pud))
1500 goto no_page_table;
1501 if (pud_huge(*pud) && vma->vm_flags & VM_HUGETLB) {
1502 if (flags & FOLL_GET)
1503 goto out;
1504 page = follow_huge_pud(mm, address, pud, flags & FOLL_WRITE);
1505 goto out;
1506 }
1507 if (unlikely(pud_bad(*pud)))
1508 goto no_page_table;
1509
1510 pmd = pmd_offset(pud, address);
1511 if (pmd_none(*pmd))
1512 goto no_page_table;
1513 if (pmd_huge(*pmd) && vma->vm_flags & VM_HUGETLB) {
1514 page = follow_huge_pmd(mm, address, pmd, flags & FOLL_WRITE);
1515 if (flags & FOLL_GET) {
1516 /*
1517 * Refcount on tail pages are not well-defined and
1518 * shouldn't be taken. The caller should handle a NULL
1519 * return when trying to follow tail pages.
1520 */
1521 if (PageHead(page))
1522 get_page(page);
1523 else {
1524 page = NULL;
1525 goto out;
1526 }
1527 }
1528 goto out;
1529 }
1530 if ((flags & FOLL_NUMA) && pmd_numa(*pmd))
1531 goto no_page_table;
1532 if (pmd_trans_huge(*pmd)) {
1533 if (flags & FOLL_SPLIT) {
1534 split_huge_page_pmd(vma, address, pmd);
1535 goto split_fallthrough;
1536 }
1537 ptl = pmd_lock(mm, pmd);
1538 if (likely(pmd_trans_huge(*pmd))) {
1539 if (unlikely(pmd_trans_splitting(*pmd))) {
1540 spin_unlock(ptl);
1541 wait_split_huge_page(vma->anon_vma, pmd);
1542 } else {
1543 page = follow_trans_huge_pmd(vma, address,
1544 pmd, flags);
1545 spin_unlock(ptl);
1546 *page_mask = HPAGE_PMD_NR - 1;
1547 goto out;
1548 }
1549 } else
1550 spin_unlock(ptl);
1551 /* fall through */
1552 }
1553split_fallthrough:
1554 if (unlikely(pmd_bad(*pmd)))
1555 goto no_page_table;
1556
1557 ptep = pte_offset_map_lock(mm, pmd, address, &ptl);
1558
1559 pte = *ptep;
1560 if (!pte_present(pte)) {
1561 swp_entry_t entry;
1562 /*
1563 * KSM's break_ksm() relies upon recognizing a ksm page
1564 * even while it is being migrated, so for that case we
1565 * need migration_entry_wait().
1566 */
1567 if (likely(!(flags & FOLL_MIGRATION)))
1568 goto no_page;
1569 if (pte_none(pte) || pte_file(pte))
1570 goto no_page;
1571 entry = pte_to_swp_entry(pte);
1572 if (!is_migration_entry(entry))
1573 goto no_page;
1574 pte_unmap_unlock(ptep, ptl);
1575 migration_entry_wait(mm, pmd, address);
1576 goto split_fallthrough;
1577 }
1578 if ((flags & FOLL_NUMA) && pte_numa(pte))
1579 goto no_page;
1580 if ((flags & FOLL_WRITE) && !pte_write(pte))
1581 goto unlock;
1582
1583 page = vm_normal_page(vma, address, pte);
1584 if (unlikely(!page)) {
1585 if ((flags & FOLL_DUMP) ||
1586 !is_zero_pfn(pte_pfn(pte)))
1587 goto bad_page;
1588 page = pte_page(pte);
1589 }
1590
1591 if (flags & FOLL_GET)
1592 get_page_foll(page);
1593 if (flags & FOLL_TOUCH) {
1594 if ((flags & FOLL_WRITE) &&
1595 !pte_dirty(pte) && !PageDirty(page))
1596 set_page_dirty(page);
1597 /*
1598 * pte_mkyoung() would be more correct here, but atomic care
1599 * is needed to avoid losing the dirty bit: it is easier to use
1600 * mark_page_accessed().
1601 */
1602 mark_page_accessed(page);
1603 }
1604 if ((flags & FOLL_MLOCK) && (vma->vm_flags & VM_LOCKED)) {
1605 /*
1606 * The preliminary mapping check is mainly to avoid the
1607 * pointless overhead of lock_page on the ZERO_PAGE
1608 * which might bounce very badly if there is contention.
1609 *
1610 * If the page is already locked, we don't need to
1611 * handle it now - vmscan will handle it later if and
1612 * when it attempts to reclaim the page.
1613 */
1614 if (page->mapping && trylock_page(page)) {
1615 lru_add_drain(); /* push cached pages to LRU */
1616 /*
1617 * Because we lock page here, and migration is
1618 * blocked by the pte's page reference, and we
1619 * know the page is still mapped, we don't even
1620 * need to check for file-cache page truncation.
1621 */
1622 mlock_vma_page(page);
1623 unlock_page(page);
1624 }
1625 }
1626unlock:
1627 pte_unmap_unlock(ptep, ptl);
1628out:
1629 return page;
1630
1631bad_page:
1632 pte_unmap_unlock(ptep, ptl);
1633 return ERR_PTR(-EFAULT);
1634
1635no_page:
1636 pte_unmap_unlock(ptep, ptl);
1637 if (!pte_none(pte))
1638 return page;
1639
1640no_page_table:
1641 /*
1642 * When core dumping an enormous anonymous area that nobody
1643 * has touched so far, we don't want to allocate unnecessary pages or
1644 * page tables. Return error instead of NULL to skip handle_mm_fault,
1645 * then get_dump_page() will return NULL to leave a hole in the dump.
1646 * But we can only make this optimization where a hole would surely
1647 * be zero-filled if handle_mm_fault() actually did handle it.
1648 */
1649 if ((flags & FOLL_DUMP) &&
1650 (!vma->vm_ops || !vma->vm_ops->fault))
1651 return ERR_PTR(-EFAULT);
1652 return page;
1653}
1654
1655static inline int stack_guard_page(struct vm_area_struct *vma, unsigned long addr)
1656{
1657 return stack_guard_page_start(vma, addr) ||
1658 stack_guard_page_end(vma, addr+PAGE_SIZE);
1659}
1660
1661/**
1662 * __get_user_pages() - pin user pages in memory
1663 * @tsk: task_struct of target task
1664 * @mm: mm_struct of target mm
1665 * @start: starting user address
1666 * @nr_pages: number of pages from start to pin
1667 * @gup_flags: flags modifying pin behaviour
1668 * @pages: array that receives pointers to the pages pinned.
1669 * Should be at least nr_pages long. Or NULL, if caller
1670 * only intends to ensure the pages are faulted in.
1671 * @vmas: array of pointers to vmas corresponding to each page.
1672 * Or NULL if the caller does not require them.
1673 * @nonblocking: whether waiting for disk IO or mmap_sem contention
1674 *
1675 * Returns number of pages pinned. This may be fewer than the number
1676 * requested. If nr_pages is 0 or negative, returns 0. If no pages
1677 * were pinned, returns -errno. Each page returned must be released
1678 * with a put_page() call when it is finished with. vmas will only
1679 * remain valid while mmap_sem is held.
1680 *
1681 * Must be called with mmap_sem held for read or write.
1682 *
1683 * __get_user_pages walks a process's page tables and takes a reference to
1684 * each struct page that each user address corresponds to at a given
1685 * instant. That is, it takes the page that would be accessed if a user
1686 * thread accesses the given user virtual address at that instant.
1687 *
1688 * This does not guarantee that the page exists in the user mappings when
1689 * __get_user_pages returns, and there may even be a completely different
1690 * page there in some cases (eg. if mmapped pagecache has been invalidated
1691 * and subsequently re faulted). However it does guarantee that the page
1692 * won't be freed completely. And mostly callers simply care that the page
1693 * contains data that was valid *at some point in time*. Typically, an IO
1694 * or similar operation cannot guarantee anything stronger anyway because
1695 * locks can't be held over the syscall boundary.
1696 *
1697 * If @gup_flags & FOLL_WRITE == 0, the page must not be written to. If
1698 * the page is written to, set_page_dirty (or set_page_dirty_lock, as
1699 * appropriate) must be called after the page is finished with, and
1700 * before put_page is called.
1701 *
1702 * If @nonblocking != NULL, __get_user_pages will not wait for disk IO
1703 * or mmap_sem contention, and if waiting is needed to pin all pages,
1704 * *@nonblocking will be set to 0.
1705 *
1706 * In most cases, get_user_pages or get_user_pages_fast should be used
1707 * instead of __get_user_pages. __get_user_pages should be used only if
1708 * you need some special @gup_flags.
1709 */
1710long __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
1711 unsigned long start, unsigned long nr_pages,
1712 unsigned int gup_flags, struct page **pages,
1713 struct vm_area_struct **vmas, int *nonblocking)
1714{
1715 long i;
1716 unsigned long vm_flags;
1717 unsigned int page_mask;
1718
1719 if (!nr_pages)
1720 return 0;
1721
1722 VM_BUG_ON(!!pages != !!(gup_flags & FOLL_GET));
1723
1724 /*
1725 * If FOLL_FORCE and FOLL_NUMA are both set, handle_mm_fault
1726 * would be called on PROT_NONE ranges. We must never invoke
1727 * handle_mm_fault on PROT_NONE ranges or the NUMA hinting
1728 * page faults would unprotect the PROT_NONE ranges if
1729 * _PAGE_NUMA and _PAGE_PROTNONE are sharing the same pte/pmd
1730 * bitflag. So to avoid that, don't set FOLL_NUMA if
1731 * FOLL_FORCE is set.
1732 */
1733 if (!(gup_flags & FOLL_FORCE))
1734 gup_flags |= FOLL_NUMA;
1735
1736 i = 0;
1737
1738 do {
1739 struct vm_area_struct *vma;
1740
1741 vma = find_extend_vma(mm, start);
1742 if (!vma && in_gate_area(mm, start)) {
1743 unsigned long pg = start & PAGE_MASK;
1744 pgd_t *pgd;
1745 pud_t *pud;
1746 pmd_t *pmd;
1747 pte_t *pte;
1748
1749 /* user gate pages are read-only */
1750 if (gup_flags & FOLL_WRITE)
1751 goto efault;
1752 if (pg > TASK_SIZE)
1753 pgd = pgd_offset_k(pg);
1754 else
1755 pgd = pgd_offset_gate(mm, pg);
1756 BUG_ON(pgd_none(*pgd));
1757 pud = pud_offset(pgd, pg);
1758 BUG_ON(pud_none(*pud));
1759 pmd = pmd_offset(pud, pg);
1760 if (pmd_none(*pmd))
1761 goto efault;
1762 VM_BUG_ON(pmd_trans_huge(*pmd));
1763 pte = pte_offset_map(pmd, pg);
1764 if (pte_none(*pte)) {
1765 pte_unmap(pte);
1766 goto efault;
1767 }
1768 vma = get_gate_vma(mm);
1769 if (pages) {
1770 struct page *page;
1771
1772 page = vm_normal_page(vma, start, *pte);
1773 if (!page) {
1774 if (!(gup_flags & FOLL_DUMP) &&
1775 is_zero_pfn(pte_pfn(*pte)))
1776 page = pte_page(*pte);
1777 else {
1778 pte_unmap(pte);
1779 goto efault;
1780 }
1781 }
1782 pages[i] = page;
1783 get_page(page);
1784 }
1785 pte_unmap(pte);
1786 page_mask = 0;
1787 goto next_page;
1788 }
1789
1790 if (!vma)
1791 goto efault;
1792 vm_flags = vma->vm_flags;
1793 if (vm_flags & (VM_IO | VM_PFNMAP))
1794 goto efault;
1795
1796 if (gup_flags & FOLL_WRITE) {
1797 if (!(vm_flags & VM_WRITE)) {
1798 if (!(gup_flags & FOLL_FORCE))
1799 goto efault;
1800 /*
1801 * We used to let the write,force case do COW
1802 * in a VM_MAYWRITE VM_SHARED !VM_WRITE vma, so
1803 * ptrace could set a breakpoint in a read-only
1804 * mapping of an executable, without corrupting
1805 * the file (yet only when that file had been
1806 * opened for writing!). Anon pages in shared
1807 * mappings are surprising: now just reject it.
1808 */
1809 if (!is_cow_mapping(vm_flags)) {
1810 WARN_ON_ONCE(vm_flags & VM_MAYWRITE);
1811 goto efault;
1812 }
1813 }
1814 } else {
1815 if (!(vm_flags & VM_READ)) {
1816 if (!(gup_flags & FOLL_FORCE))
1817 goto efault;
1818 /*
1819 * Is there actually any vma we can reach here
1820 * which does not have VM_MAYREAD set?
1821 */
1822 if (!(vm_flags & VM_MAYREAD))
1823 goto efault;
1824 }
1825 }
1826
1827 if (is_vm_hugetlb_page(vma)) {
1828 i = follow_hugetlb_page(mm, vma, pages, vmas,
1829 &start, &nr_pages, i, gup_flags);
1830 continue;
1831 }
1832
1833 do {
1834 struct page *page;
1835 unsigned int foll_flags = gup_flags;
1836 unsigned int page_increm;
1837
1838 /*
1839 * If we have a pending SIGKILL, don't keep faulting
1840 * pages and potentially allocating memory.
1841 */
1842 if (unlikely(fatal_signal_pending(current)))
1843 return i ? i : -ERESTARTSYS;
1844
1845 cond_resched();
1846 while (!(page = follow_page_mask(vma, start,
1847 foll_flags, &page_mask))) {
1848 int ret;
1849 unsigned int fault_flags = 0;
1850
1851 /* For mlock, just skip the stack guard page. */
1852 if (foll_flags & FOLL_MLOCK) {
1853 if (stack_guard_page(vma, start))
1854 goto next_page;
1855 }
1856 if (foll_flags & FOLL_WRITE)
1857 fault_flags |= FAULT_FLAG_WRITE;
1858 if (nonblocking)
1859 fault_flags |= FAULT_FLAG_ALLOW_RETRY;
1860 if (foll_flags & FOLL_NOWAIT)
1861 fault_flags |= (FAULT_FLAG_ALLOW_RETRY | FAULT_FLAG_RETRY_NOWAIT);
1862
1863 ret = handle_mm_fault(mm, vma, start,
1864 fault_flags);
1865
1866 if (ret & VM_FAULT_ERROR) {
1867 if (ret & VM_FAULT_OOM)
1868 return i ? i : -ENOMEM;
1869 if (ret & (VM_FAULT_HWPOISON |
1870 VM_FAULT_HWPOISON_LARGE)) {
1871 if (i)
1872 return i;
1873 else if (gup_flags & FOLL_HWPOISON)
1874 return -EHWPOISON;
1875 else
1876 return -EFAULT;
1877 }
1878 if (ret & VM_FAULT_SIGBUS)
1879 goto efault;
1880 BUG();
1881 }
1882
1883 if (tsk) {
1884 if (ret & VM_FAULT_MAJOR)
1885 tsk->maj_flt++;
1886 else
1887 tsk->min_flt++;
1888 }
1889
1890 if (ret & VM_FAULT_RETRY) {
1891 if (nonblocking)
1892 *nonblocking = 0;
1893 return i;
1894 }
1895
1896 /*
1897 * The VM_FAULT_WRITE bit tells us that
1898 * do_wp_page has broken COW when necessary,
1899 * even if maybe_mkwrite decided not to set
1900 * pte_write. We can thus safely do subsequent
1901 * page lookups as if they were reads. But only
1902 * do so when looping for pte_write is futile:
1903 * in some cases userspace may also be wanting
1904 * to write to the gotten user page, which a
1905 * read fault here might prevent (a readonly
1906 * page might get reCOWed by userspace write).
1907 */
1908 if ((ret & VM_FAULT_WRITE) &&
1909 !(vma->vm_flags & VM_WRITE))
1910 foll_flags &= ~FOLL_WRITE;
1911
1912 cond_resched();
1913 }
1914 if (IS_ERR(page))
1915 return i ? i : PTR_ERR(page);
1916 if (pages) {
1917 pages[i] = page;
1918
1919 flush_anon_page(vma, page, start);
1920 flush_dcache_page(page);
1921 page_mask = 0;
1922 }
1923next_page:
1924 if (vmas) {
1925 vmas[i] = vma;
1926 page_mask = 0;
1927 }
1928 page_increm = 1 + (~(start >> PAGE_SHIFT) & page_mask);
1929 if (page_increm > nr_pages)
1930 page_increm = nr_pages;
1931 i += page_increm;
1932 start += page_increm * PAGE_SIZE;
1933 nr_pages -= page_increm;
1934 } while (nr_pages && start < vma->vm_end);
1935 } while (nr_pages);
1936 return i;
1937efault:
1938 return i ? : -EFAULT;
1939}
1940EXPORT_SYMBOL(__get_user_pages);
1941
1942/*
1943 * fixup_user_fault() - manually resolve a user page fault
1944 * @tsk: the task_struct to use for page fault accounting, or
1945 * NULL if faults are not to be recorded.
1946 * @mm: mm_struct of target mm
1947 * @address: user address
1948 * @fault_flags:flags to pass down to handle_mm_fault()
1949 *
1950 * This is meant to be called in the specific scenario where for locking reasons
1951 * we try to access user memory in atomic context (within a pagefault_disable()
1952 * section), this returns -EFAULT, and we want to resolve the user fault before
1953 * trying again.
1954 *
1955 * Typically this is meant to be used by the futex code.
1956 *
1957 * The main difference with get_user_pages() is that this function will
1958 * unconditionally call handle_mm_fault() which will in turn perform all the
1959 * necessary SW fixup of the dirty and young bits in the PTE, while
1960 * handle_mm_fault() only guarantees to update these in the struct page.
1961 *
1962 * This is important for some architectures where those bits also gate the
1963 * access permission to the page because they are maintained in software. On
1964 * such architectures, gup() will not be enough to make a subsequent access
1965 * succeed.
1966 *
1967 * This should be called with the mm_sem held for read.
1968 */
1969int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
1970 unsigned long address, unsigned int fault_flags)
1971{
1972 struct vm_area_struct *vma;
1973 vm_flags_t vm_flags;
1974 int ret;
1975
1976 vma = find_extend_vma(mm, address);
1977 if (!vma || address < vma->vm_start)
1978 return -EFAULT;
1979
1980 vm_flags = (fault_flags & FAULT_FLAG_WRITE) ? VM_WRITE : VM_READ;
1981 if (!(vm_flags & vma->vm_flags))
1982 return -EFAULT;
1983
1984 ret = handle_mm_fault(mm, vma, address, fault_flags);
1985 if (ret & VM_FAULT_ERROR) {
1986 if (ret & VM_FAULT_OOM)
1987 return -ENOMEM;
1988 if (ret & (VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_LARGE))
1989 return -EHWPOISON;
1990 if (ret & VM_FAULT_SIGBUS)
1991 return -EFAULT;
1992 BUG();
1993 }
1994 if (tsk) {
1995 if (ret & VM_FAULT_MAJOR)
1996 tsk->maj_flt++;
1997 else
1998 tsk->min_flt++;
1999 }
2000 return 0;
2001}
2002
2003/*
2004 * get_user_pages() - pin user pages in memory
2005 * @tsk: the task_struct to use for page fault accounting, or
2006 * NULL if faults are not to be recorded.
2007 * @mm: mm_struct of target mm
2008 * @start: starting user address
2009 * @nr_pages: number of pages from start to pin
2010 * @write: whether pages will be written to by the caller
2011 * @force: whether to force access even when user mapping is currently
2012 * protected (but never forces write access to shared mapping).
2013 * @pages: array that receives pointers to the pages pinned.
2014 * Should be at least nr_pages long. Or NULL, if caller
2015 * only intends to ensure the pages are faulted in.
2016 * @vmas: array of pointers to vmas corresponding to each page.
2017 * Or NULL if the caller does not require them.
2018 *
2019 * Returns number of pages pinned. This may be fewer than the number
2020 * requested. If nr_pages is 0 or negative, returns 0. If no pages
2021 * were pinned, returns -errno. Each page returned must be released
2022 * with a put_page() call when it is finished with. vmas will only
2023 * remain valid while mmap_sem is held.
2024 *
2025 * Must be called with mmap_sem held for read or write.
2026 *
2027 * get_user_pages walks a process's page tables and takes a reference to
2028 * each struct page that each user address corresponds to at a given
2029 * instant. That is, it takes the page that would be accessed if a user
2030 * thread accesses the given user virtual address at that instant.
2031 *
2032 * This does not guarantee that the page exists in the user mappings when
2033 * get_user_pages returns, and there may even be a completely different
2034 * page there in some cases (eg. if mmapped pagecache has been invalidated
2035 * and subsequently re faulted). However it does guarantee that the page
2036 * won't be freed completely. And mostly callers simply care that the page
2037 * contains data that was valid *at some point in time*. Typically, an IO
2038 * or similar operation cannot guarantee anything stronger anyway because
2039 * locks can't be held over the syscall boundary.
2040 *
2041 * If write=0, the page must not be written to. If the page is written to,
2042 * set_page_dirty (or set_page_dirty_lock, as appropriate) must be called
2043 * after the page is finished with, and before put_page is called.
2044 *
2045 * get_user_pages is typically used for fewer-copy IO operations, to get a
2046 * handle on the memory by some means other than accesses via the user virtual
2047 * addresses. The pages may be submitted for DMA to devices or accessed via
2048 * their kernel linear mapping (via the kmap APIs). Care should be taken to
2049 * use the correct cache flushing APIs.
2050 *
2051 * See also get_user_pages_fast, for performance critical applications.
2052 */
2053long get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
2054 unsigned long start, unsigned long nr_pages, int write,
2055 int force, struct page **pages, struct vm_area_struct **vmas)
2056{
2057 int flags = FOLL_TOUCH;
2058
2059 if (pages)
2060 flags |= FOLL_GET;
2061 if (write)
2062 flags |= FOLL_WRITE;
2063 if (force)
2064 flags |= FOLL_FORCE;
2065
2066 return __get_user_pages(tsk, mm, start, nr_pages, flags, pages, vmas,
2067 NULL);
2068}
2069EXPORT_SYMBOL(get_user_pages);
2070
2071/**
2072 * get_dump_page() - pin user page in memory while writing it to core dump
2073 * @addr: user address
2074 *
2075 * Returns struct page pointer of user page pinned for dump,
2076 * to be freed afterwards by page_cache_release() or put_page().
2077 *
2078 * Returns NULL on any kind of failure - a hole must then be inserted into
2079 * the corefile, to preserve alignment with its headers; and also returns
2080 * NULL wherever the ZERO_PAGE, or an anonymous pte_none, has been found -
2081 * allowing a hole to be left in the corefile to save diskspace.
2082 *
2083 * Called without mmap_sem, but after all other threads have been killed.
2084 */
2085#ifdef CONFIG_ELF_CORE
2086struct page *get_dump_page(unsigned long addr)
2087{
2088 struct vm_area_struct *vma;
2089 struct page *page;
2090
2091 if (__get_user_pages(current, current->mm, addr, 1,
2092 FOLL_FORCE | FOLL_DUMP | FOLL_GET, &page, &vma,
2093 NULL) < 1)
2094 return NULL;
2095 flush_cache_page(vma, addr, page_to_pfn(page));
2096 return page;
2097}
2098#endif /* CONFIG_ELF_CORE */
2099
2100pte_t *__get_locked_pte(struct mm_struct *mm, unsigned long addr,
2101 spinlock_t **ptl)
2102{
2103 pgd_t * pgd = pgd_offset(mm, addr);
2104 pud_t * pud = pud_alloc(mm, pgd, addr);
2105 if (pud) {
2106 pmd_t * pmd = pmd_alloc(mm, pud, addr);
2107 if (pmd) {
2108 VM_BUG_ON(pmd_trans_huge(*pmd));
2109 return pte_alloc_map_lock(mm, pmd, addr, ptl);
2110 }
2111 }
2112 return NULL;
2113}
2114
2115/*
2116 * This is the old fallback for page remapping.
2117 *
2118 * For historical reasons, it only allows reserved pages. Only
2119 * old drivers should use this, and they needed to mark their
2120 * pages reserved for the old functions anyway.
2121 */
2122static int insert_page(struct vm_area_struct *vma, unsigned long addr,
2123 struct page *page, pgprot_t prot)
2124{
2125 struct mm_struct *mm = vma->vm_mm;
2126 int retval;
2127 pte_t *pte;
2128 spinlock_t *ptl;
2129
2130 retval = -EINVAL;
2131 if (PageAnon(page))
2132 goto out;
2133 retval = -ENOMEM;
2134 flush_dcache_page(page);
2135 pte = get_locked_pte(mm, addr, &ptl);
2136 if (!pte)
2137 goto out;
2138 retval = -EBUSY;
2139 if (!pte_none(*pte))
2140 goto out_unlock;
2141
2142 /* Ok, finally just insert the thing.. */
2143 get_page(page);
2144 inc_mm_counter_fast(mm, MM_FILEPAGES);
2145 page_add_file_rmap(page);
2146 set_pte_at(mm, addr, pte, mk_pte(page, prot));
2147
2148 retval = 0;
2149 pte_unmap_unlock(pte, ptl);
2150 return retval;
2151out_unlock:
2152 pte_unmap_unlock(pte, ptl);
2153out:
2154 return retval;
2155}
2156
2157/**
2158 * vm_insert_page - insert single page into user vma
2159 * @vma: user vma to map to
2160 * @addr: target user address of this page
2161 * @page: source kernel page
2162 *
2163 * This allows drivers to insert individual pages they've allocated
2164 * into a user vma.
2165 *
2166 * The page has to be a nice clean _individual_ kernel allocation.
2167 * If you allocate a compound page, you need to have marked it as
2168 * such (__GFP_COMP), or manually just split the page up yourself
2169 * (see split_page()).
2170 *
2171 * NOTE! Traditionally this was done with "remap_pfn_range()" which
2172 * took an arbitrary page protection parameter. This doesn't allow
2173 * that. Your vma protection will have to be set up correctly, which
2174 * means that if you want a shared writable mapping, you'd better
2175 * ask for a shared writable mapping!
2176 *
2177 * The page does not need to be reserved.
2178 *
2179 * Usually this function is called from f_op->mmap() handler
2180 * under mm->mmap_sem write-lock, so it can change vma->vm_flags.
2181 * Caller must set VM_MIXEDMAP on vma if it wants to call this
2182 * function from other places, for example from page-fault handler.
2183 */
2184int vm_insert_page(struct vm_area_struct *vma, unsigned long addr,
2185 struct page *page)
2186{
2187 if (addr < vma->vm_start || addr >= vma->vm_end)
2188 return -EFAULT;
2189 if (!page_count(page))
2190 return -EINVAL;
2191 if (!(vma->vm_flags & VM_MIXEDMAP)) {
2192 BUG_ON(down_read_trylock(&vma->vm_mm->mmap_sem));
2193 BUG_ON(vma->vm_flags & VM_PFNMAP);
2194 vma->vm_flags |= VM_MIXEDMAP;
2195 }
2196 return insert_page(vma, addr, page, vma->vm_page_prot);
2197}
2198EXPORT_SYMBOL(vm_insert_page);
2199
2200static int insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2201 unsigned long pfn, pgprot_t prot)
2202{
2203 struct mm_struct *mm = vma->vm_mm;
2204 int retval;
2205 pte_t *pte, entry;
2206 spinlock_t *ptl;
2207
2208 retval = -ENOMEM;
2209 pte = get_locked_pte(mm, addr, &ptl);
2210 if (!pte)
2211 goto out;
2212 retval = -EBUSY;
2213 if (!pte_none(*pte))
2214 goto out_unlock;
2215
2216 /* Ok, finally just insert the thing.. */
2217 entry = pte_mkspecial(pfn_pte(pfn, prot));
2218 set_pte_at(mm, addr, pte, entry);
2219 update_mmu_cache(vma, addr, pte); /* XXX: why not for insert_page? */
2220
2221 retval = 0;
2222out_unlock:
2223 pte_unmap_unlock(pte, ptl);
2224out:
2225 return retval;
2226}
2227
2228/**
2229 * vm_insert_pfn - insert single pfn into user vma
2230 * @vma: user vma to map to
2231 * @addr: target user address of this page
2232 * @pfn: source kernel pfn
2233 *
2234 * Similar to vm_insert_page, this allows drivers to insert individual pages
2235 * they've allocated into a user vma. Same comments apply.
2236 *
2237 * This function should only be called from a vm_ops->fault handler, and
2238 * in that case the handler should return NULL.
2239 *
2240 * vma cannot be a COW mapping.
2241 *
2242 * As this is called only for pages that do not currently exist, we
2243 * do not need to flush old virtual caches or the TLB.
2244 */
2245int vm_insert_pfn(struct vm_area_struct *vma, unsigned long addr,
2246 unsigned long pfn)
2247{
2248 int ret;
2249 pgprot_t pgprot = vma->vm_page_prot;
2250 /*
2251 * Technically, architectures with pte_special can avoid all these
2252 * restrictions (same for remap_pfn_range). However we would like
2253 * consistency in testing and feature parity among all, so we should
2254 * try to keep these invariants in place for everybody.
2255 */
2256 BUG_ON(!(vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)));
2257 BUG_ON((vma->vm_flags & (VM_PFNMAP|VM_MIXEDMAP)) ==
2258 (VM_PFNMAP|VM_MIXEDMAP));
2259 BUG_ON((vma->vm_flags & VM_PFNMAP) && is_cow_mapping(vma->vm_flags));
2260 BUG_ON((vma->vm_flags & VM_MIXEDMAP) && pfn_valid(pfn));
2261
2262 if (addr < vma->vm_start || addr >= vma->vm_end)
2263 return -EFAULT;
2264 if (track_pfn_insert(vma, &pgprot, pfn))
2265 return -EINVAL;
2266
2267 ret = insert_pfn(vma, addr, pfn, pgprot);
2268
2269 return ret;
2270}
2271EXPORT_SYMBOL(vm_insert_pfn);
2272
2273int vm_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
2274 unsigned long pfn)
2275{
2276 BUG_ON(!(vma->vm_flags & VM_MIXEDMAP));
2277
2278 if (addr < vma->vm_start || addr >= vma->vm_end)
2279 return -EFAULT;
2280
2281 /*
2282 * If we don't have pte special, then we have to use the pfn_valid()
2283 * based VM_MIXEDMAP scheme (see vm_normal_page), and thus we *must*
2284 * refcount the page if pfn_valid is true (hence insert_page rather
2285 * than insert_pfn). If a zero_pfn were inserted into a VM_MIXEDMAP
2286 * without pte special, it would there be refcounted as a normal page.
2287 */
2288 if (!HAVE_PTE_SPECIAL && pfn_valid(pfn)) {
2289 struct page *page;
2290
2291 page = pfn_to_page(pfn);
2292 return insert_page(vma, addr, page, vma->vm_page_prot);
2293 }
2294 return insert_pfn(vma, addr, pfn, vma->vm_page_prot);
2295}
2296EXPORT_SYMBOL(vm_insert_mixed);
2297
2298/*
2299 * maps a range of physical memory into the requested pages. the old
2300 * mappings are removed. any references to nonexistent pages results
2301 * in null mappings (currently treated as "copy-on-access")
2302 */
2303static int remap_pte_range(struct mm_struct *mm, pmd_t *pmd,
2304 unsigned long addr, unsigned long end,
2305 unsigned long pfn, pgprot_t prot)
2306{
2307 pte_t *pte;
2308 spinlock_t *ptl;
2309
2310 pte = pte_alloc_map_lock(mm, pmd, addr, &ptl);
2311 if (!pte)
2312 return -ENOMEM;
2313 arch_enter_lazy_mmu_mode();
2314 do {
2315 BUG_ON(!pte_none(*pte));
2316 set_pte_at(mm, addr, pte, pte_mkspecial(pfn_pte(pfn, prot)));
2317 pfn++;
2318 } while (pte++, addr += PAGE_SIZE, addr != end);
2319 arch_leave_lazy_mmu_mode();
2320 pte_unmap_unlock(pte - 1, ptl);
2321 return 0;
2322}
2323
2324static inline int remap_pmd_range(struct mm_struct *mm, pud_t *pud,
2325 unsigned long addr, unsigned long end,
2326 unsigned long pfn, pgprot_t prot)
2327{
2328 pmd_t *pmd;
2329 unsigned long next;
2330
2331 pfn -= addr >> PAGE_SHIFT;
2332 pmd = pmd_alloc(mm, pud, addr);
2333 if (!pmd)
2334 return -ENOMEM;
2335 VM_BUG_ON(pmd_trans_huge(*pmd));
2336 do {
2337 next = pmd_addr_end(addr, end);
2338 if (remap_pte_range(mm, pmd, addr, next,
2339 pfn + (addr >> PAGE_SHIFT), prot))
2340 return -ENOMEM;
2341 } while (pmd++, addr = next, addr != end);
2342 return 0;
2343}
2344
2345static inline int remap_pud_range(struct mm_struct *mm, pgd_t *pgd,
2346 unsigned long addr, unsigned long end,
2347 unsigned long pfn, pgprot_t prot)
2348{
2349 pud_t *pud;
2350 unsigned long next;
2351
2352 pfn -= addr >> PAGE_SHIFT;
2353 pud = pud_alloc(mm, pgd, addr);
2354 if (!pud)
2355 return -ENOMEM;
2356 do {
2357 next = pud_addr_end(addr, end);
2358 if (remap_pmd_range(mm, pud, addr, next,
2359 pfn + (addr >> PAGE_SHIFT), prot))
2360 return -ENOMEM;
2361 } while (pud++, addr = next, addr != end);
2362 return 0;
2363}
2364
2365/**
2366 * remap_pfn_range - remap kernel memory to userspace
2367 * @vma: user vma to map to
2368 * @addr: target user address to start at
2369 * @pfn: physical address of kernel memory
2370 * @size: size of map area
2371 * @prot: page protection flags for this mapping
2372 *
2373 * Note: this is only safe if the mm semaphore is held when called.
2374 */
2375int remap_pfn_range(struct vm_area_struct *vma, unsigned long addr,
2376 unsigned long pfn, unsigned long size, pgprot_t prot)
2377{
2378 pgd_t *pgd;
2379 unsigned long next;
2380 unsigned long end = addr + PAGE_ALIGN(size);
2381 struct mm_struct *mm = vma->vm_mm;
2382 int err;
2383
2384 /*
2385 * Physically remapped pages are special. Tell the
2386 * rest of the world about it:
2387 * VM_IO tells people not to look at these pages
2388 * (accesses can have side effects).
2389 * VM_PFNMAP tells the core MM that the base pages are just
2390 * raw PFN mappings, and do not have a "struct page" associated
2391 * with them.
2392 * VM_DONTEXPAND
2393 * Disable vma merging and expanding with mremap().
2394 * VM_DONTDUMP
2395 * Omit vma from core dump, even when VM_IO turned off.
2396 *
2397 * There's a horrible special case to handle copy-on-write
2398 * behaviour that some programs depend on. We mark the "original"
2399 * un-COW'ed pages by matching them up with "vma->vm_pgoff".
2400 * See vm_normal_page() for details.
2401 */
2402 if (is_cow_mapping(vma->vm_flags)) {
2403 if (addr != vma->vm_start || end != vma->vm_end)
2404 return -EINVAL;
2405 vma->vm_pgoff = pfn;
2406 }
2407
2408 err = track_pfn_remap(vma, &prot, pfn, addr, PAGE_ALIGN(size));
2409 if (err)
2410 return -EINVAL;
2411
2412 vma->vm_flags |= VM_IO | VM_PFNMAP | VM_DONTEXPAND | VM_DONTDUMP;
2413
2414 BUG_ON(addr >= end);
2415 pfn -= addr >> PAGE_SHIFT;
2416 pgd = pgd_offset(mm, addr);
2417 flush_cache_range(vma, addr, end);
2418 do {
2419 next = pgd_addr_end(addr, end);
2420 err = remap_pud_range(mm, pgd, addr, next,
2421 pfn + (addr >> PAGE_SHIFT), prot);
2422 if (err)
2423 break;
2424 } while (pgd++, addr = next, addr != end);
2425
2426 if (err)
2427 untrack_pfn(vma, pfn, PAGE_ALIGN(size));
2428
2429 return err;
2430}
2431EXPORT_SYMBOL(remap_pfn_range);
2432
2433/**
2434 * vm_iomap_memory - remap memory to userspace
2435 * @vma: user vma to map to
2436 * @start: start of area
2437 * @len: size of area
2438 *
2439 * This is a simplified io_remap_pfn_range() for common driver use. The
2440 * driver just needs to give us the physical memory range to be mapped,
2441 * we'll figure out the rest from the vma information.
2442 *
2443 * NOTE! Some drivers might want to tweak vma->vm_page_prot first to get
2444 * whatever write-combining details or similar.
2445 */
2446int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len)
2447{
2448 unsigned long vm_len, pfn, pages;
2449
2450 /* Check that the physical memory area passed in looks valid */
2451 if (start + len < start)
2452 return -EINVAL;
2453 /*
2454 * You *really* shouldn't map things that aren't page-aligned,
2455 * but we've historically allowed it because IO memory might
2456 * just have smaller alignment.
2457 */
2458 len += start & ~PAGE_MASK;
2459 pfn = start >> PAGE_SHIFT;
2460 pages = (len + ~PAGE_MASK) >> PAGE_SHIFT;
2461 if (pfn + pages < pfn)
2462 return -EINVAL;
2463
2464 /* We start the mapping 'vm_pgoff' pages into the area */
2465 if (vma->vm_pgoff > pages)
2466 return -EINVAL;
2467 pfn += vma->vm_pgoff;
2468 pages -= vma->vm_pgoff;
2469
2470 /* Can we fit all of the mapping? */
2471 vm_len = vma->vm_end - vma->vm_start;
2472 if (vm_len >> PAGE_SHIFT > pages)
2473 return -EINVAL;
2474
2475 /* Ok, let it rip */
2476 return io_remap_pfn_range(vma, vma->vm_start, pfn, vm_len, vma->vm_page_prot);
2477}
2478EXPORT_SYMBOL(vm_iomap_memory);
2479
2480static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
2481 unsigned long addr, unsigned long end,
2482 pte_fn_t fn, void *data)
2483{
2484 pte_t *pte;
2485 int err;
2486 pgtable_t token;
2487 spinlock_t *uninitialized_var(ptl);
2488
2489 pte = (mm == &init_mm) ?
2490 pte_alloc_kernel(pmd, addr) :
2491 pte_alloc_map_lock(mm, pmd, addr, &ptl);
2492 if (!pte)
2493 return -ENOMEM;
2494
2495 BUG_ON(pmd_huge(*pmd));
2496
2497 arch_enter_lazy_mmu_mode();
2498
2499 token = pmd_pgtable(*pmd);
2500
2501 do {
2502 err = fn(pte++, token, addr, data);
2503 if (err)
2504 break;
2505 } while (addr += PAGE_SIZE, addr != end);
2506
2507 arch_leave_lazy_mmu_mode();
2508
2509 if (mm != &init_mm)
2510 pte_unmap_unlock(pte-1, ptl);
2511 return err;
2512}
2513
2514static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
2515 unsigned long addr, unsigned long end,
2516 pte_fn_t fn, void *data)
2517{
2518 pmd_t *pmd;
2519 unsigned long next;
2520 int err;
2521
2522 BUG_ON(pud_huge(*pud));
2523
2524 pmd = pmd_alloc(mm, pud, addr);
2525 if (!pmd)
2526 return -ENOMEM;
2527 do {
2528 next = pmd_addr_end(addr, end);
2529 err = apply_to_pte_range(mm, pmd, addr, next, fn, data);
2530 if (err)
2531 break;
2532 } while (pmd++, addr = next, addr != end);
2533 return err;
2534}
2535
2536static int apply_to_pud_range(struct mm_struct *mm, pgd_t *pgd,
2537 unsigned long addr, unsigned long end,
2538 pte_fn_t fn, void *data)
2539{
2540 pud_t *pud;
2541 unsigned long next;
2542 int err;
2543
2544 pud = pud_alloc(mm, pgd, addr);
2545 if (!pud)
2546 return -ENOMEM;
2547 do {
2548 next = pud_addr_end(addr, end);
2549 err = apply_to_pmd_range(mm, pud, addr, next, fn, data);
2550 if (err)
2551 break;
2552 } while (pud++, addr = next, addr != end);
2553 return err;
2554}
2555
2556/*
2557 * Scan a region of virtual memory, filling in page tables as necessary
2558 * and calling a provided function on each leaf page table.
2559 */
2560int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
2561 unsigned long size, pte_fn_t fn, void *data)
2562{
2563 pgd_t *pgd;
2564 unsigned long next;
2565 unsigned long end = addr + size;
2566 int err;
2567
2568 BUG_ON(addr >= end);
2569 pgd = pgd_offset(mm, addr);
2570 do {
2571 next = pgd_addr_end(addr, end);
2572 err = apply_to_pud_range(mm, pgd, addr, next, fn, data);
2573 if (err)
2574 break;
2575 } while (pgd++, addr = next, addr != end);
2576
2577 return err;
2578}
2579EXPORT_SYMBOL_GPL(apply_to_page_range);
2580
2581/*
2582 * handle_pte_fault chooses page fault handler according to an entry
2583 * which was read non-atomically. Before making any commitment, on
2584 * those architectures or configurations (e.g. i386 with PAE) which
2585 * might give a mix of unmatched parts, do_swap_page and do_nonlinear_fault
2586 * must check under lock before unmapping the pte and proceeding
2587 * (but do_wp_page is only called after already making such a check;
2588 * and do_anonymous_page can safely check later on).
2589 */
2590static inline int pte_unmap_same(struct mm_struct *mm, pmd_t *pmd,
2591 pte_t *page_table, pte_t orig_pte)
2592{
2593 int same = 1;
2594#if defined(CONFIG_SMP) || defined(CONFIG_PREEMPT)
2595 if (sizeof(pte_t) > sizeof(unsigned long)) {
2596 spinlock_t *ptl = pte_lockptr(mm, pmd);
2597 spin_lock(ptl);
2598 same = pte_same(*page_table, orig_pte);
2599 spin_unlock(ptl);
2600 }
2601#endif
2602 pte_unmap(page_table);
2603 return same;
2604}
2605
2606static inline void cow_user_page(struct page *dst, struct page *src, unsigned long va, struct vm_area_struct *vma)
2607{
2608 debug_dma_assert_idle(src);
2609
2610 /*
2611 * If the source page was a PFN mapping, we don't have
2612 * a "struct page" for it. We do a best-effort copy by
2613 * just copying from the original user address. If that
2614 * fails, we just zero-fill it. Live with it.
2615 */
2616 if (unlikely(!src)) {
2617 void *kaddr = kmap_atomic(dst);
2618 void __user *uaddr = (void __user *)(va & PAGE_MASK);
2619
2620 /*
2621 * This really shouldn't fail, because the page is there
2622 * in the page tables. But it might just be unreadable,
2623 * in which case we just give up and fill the result with
2624 * zeroes.
2625 */
2626 if (__copy_from_user_inatomic(kaddr, uaddr, PAGE_SIZE))
2627 clear_page(kaddr);
2628 kunmap_atomic(kaddr);
2629 flush_dcache_page(dst);
2630 } else
2631 copy_user_highpage(dst, src, va, vma);
2632}
2633
2634/*
2635 * Notify the address space that the page is about to become writable so that
2636 * it can prohibit this or wait for the page to get into an appropriate state.
2637 *
2638 * We do this without the lock held, so that it can sleep if it needs to.
2639 */
2640static int do_page_mkwrite(struct vm_area_struct *vma, struct page *page,
2641 unsigned long address)
2642{
2643 struct vm_fault vmf;
2644 int ret;
2645
2646 vmf.virtual_address = (void __user *)(address & PAGE_MASK);
2647 vmf.pgoff = page->index;
2648 vmf.flags = FAULT_FLAG_WRITE|FAULT_FLAG_MKWRITE;
2649 vmf.page = page;
2650
2651 ret = vma->vm_ops->page_mkwrite(vma, &vmf);
2652 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
2653 return ret;
2654 if (unlikely(!(ret & VM_FAULT_LOCKED))) {
2655 lock_page(page);
2656 if (!page->mapping) {
2657 unlock_page(page);
2658 return 0; /* retry */
2659 }
2660 ret |= VM_FAULT_LOCKED;
2661 } else
2662 VM_BUG_ON_PAGE(!PageLocked(page), page);
2663 return ret;
2664}
2665
2666/*
2667 * This routine handles present pages, when users try to write
2668 * to a shared page. It is done by copying the page to a new address
2669 * and decrementing the shared-page counter for the old page.
2670 *
2671 * Note that this routine assumes that the protection checks have been
2672 * done by the caller (the low-level page fault routine in most cases).
2673 * Thus we can safely just mark it writable once we've done any necessary
2674 * COW.
2675 *
2676 * We also mark the page dirty at this point even though the page will
2677 * change only once the write actually happens. This avoids a few races,
2678 * and potentially makes it more efficient.
2679 *
2680 * We enter with non-exclusive mmap_sem (to exclude vma changes,
2681 * but allow concurrent faults), with pte both mapped and locked.
2682 * We return with mmap_sem still held, but pte unmapped and unlocked.
2683 */
2684static int do_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
2685 unsigned long address, pte_t *page_table, pmd_t *pmd,
2686 spinlock_t *ptl, pte_t orig_pte)
2687 __releases(ptl)
2688{
2689 struct page *old_page, *new_page = NULL;
2690 pte_t entry;
2691 int ret = 0;
2692 int page_mkwrite = 0;
2693 struct page *dirty_page = NULL;
2694 unsigned long mmun_start = 0; /* For mmu_notifiers */
2695 unsigned long mmun_end = 0; /* For mmu_notifiers */
2696
2697 old_page = vm_normal_page(vma, address, orig_pte);
2698 if (!old_page) {
2699 /*
2700 * VM_MIXEDMAP !pfn_valid() case
2701 *
2702 * We should not cow pages in a shared writeable mapping.
2703 * Just mark the pages writable as we can't do any dirty
2704 * accounting on raw pfn maps.
2705 */
2706 if ((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2707 (VM_WRITE|VM_SHARED))
2708 goto reuse;
2709 goto gotten;
2710 }
2711
2712 /*
2713 * Take out anonymous pages first, anonymous shared vmas are
2714 * not dirty accountable.
2715 */
2716 if (PageAnon(old_page) && !PageKsm(old_page)) {
2717 if (!trylock_page(old_page)) {
2718 page_cache_get(old_page);
2719 pte_unmap_unlock(page_table, ptl);
2720 lock_page(old_page);
2721 page_table = pte_offset_map_lock(mm, pmd, address,
2722 &ptl);
2723 if (!pte_same(*page_table, orig_pte)) {
2724 unlock_page(old_page);
2725 goto unlock;
2726 }
2727 page_cache_release(old_page);
2728 }
2729 if (reuse_swap_page(old_page)) {
2730 /*
2731 * The page is all ours. Move it to our anon_vma so
2732 * the rmap code will not search our parent or siblings.
2733 * Protected against the rmap code by the page lock.
2734 */
2735 page_move_anon_rmap(old_page, vma, address);
2736 unlock_page(old_page);
2737 goto reuse;
2738 }
2739 unlock_page(old_page);
2740 } else if (unlikely((vma->vm_flags & (VM_WRITE|VM_SHARED)) ==
2741 (VM_WRITE|VM_SHARED))) {
2742 /*
2743 * Only catch write-faults on shared writable pages,
2744 * read-only shared pages can get COWed by
2745 * get_user_pages(.write=1, .force=1).
2746 */
2747 if (vma->vm_ops && vma->vm_ops->page_mkwrite) {
2748 int tmp;
2749 page_cache_get(old_page);
2750 pte_unmap_unlock(page_table, ptl);
2751 tmp = do_page_mkwrite(vma, old_page, address);
2752 if (unlikely(!tmp || (tmp &
2753 (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
2754 page_cache_release(old_page);
2755 return tmp;
2756 }
2757 /*
2758 * Since we dropped the lock we need to revalidate
2759 * the PTE as someone else may have changed it. If
2760 * they did, we just return, as we can count on the
2761 * MMU to tell us if they didn't also make it writable.
2762 */
2763 page_table = pte_offset_map_lock(mm, pmd, address,
2764 &ptl);
2765 if (!pte_same(*page_table, orig_pte)) {
2766 unlock_page(old_page);
2767 goto unlock;
2768 }
2769
2770 page_mkwrite = 1;
2771 }
2772 dirty_page = old_page;
2773 get_page(dirty_page);
2774
2775reuse:
2776 /*
2777 * Clear the pages cpupid information as the existing
2778 * information potentially belongs to a now completely
2779 * unrelated process.
2780 */
2781 if (old_page)
2782 page_cpupid_xchg_last(old_page, (1 << LAST_CPUPID_SHIFT) - 1);
2783
2784 flush_cache_page(vma, address, pte_pfn(orig_pte));
2785 entry = pte_mkyoung(orig_pte);
2786 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2787 if (ptep_set_access_flags(vma, address, page_table, entry,1))
2788 update_mmu_cache(vma, address, page_table);
2789 pte_unmap_unlock(page_table, ptl);
2790 ret |= VM_FAULT_WRITE;
2791
2792 if (!dirty_page)
2793 return ret;
2794
2795 /*
2796 * Yes, Virginia, this is actually required to prevent a race
2797 * with clear_page_dirty_for_io() from clearing the page dirty
2798 * bit after it clear all dirty ptes, but before a racing
2799 * do_wp_page installs a dirty pte.
2800 *
2801 * do_shared_fault is protected similarly.
2802 */
2803 if (!page_mkwrite) {
2804 wait_on_page_locked(dirty_page);
2805 set_page_dirty_balance(dirty_page);
2806 /* file_update_time outside page_lock */
2807 if (vma->vm_file)
2808 file_update_time(vma->vm_file);
2809 }
2810 put_page(dirty_page);
2811 if (page_mkwrite) {
2812 struct address_space *mapping = dirty_page->mapping;
2813
2814 set_page_dirty(dirty_page);
2815 unlock_page(dirty_page);
2816 page_cache_release(dirty_page);
2817 if (mapping) {
2818 /*
2819 * Some device drivers do not set page.mapping
2820 * but still dirty their pages
2821 */
2822 balance_dirty_pages_ratelimited(mapping);
2823 }
2824 }
2825
2826 return ret;
2827 }
2828
2829 /*
2830 * Ok, we need to copy. Oh, well..
2831 */
2832 page_cache_get(old_page);
2833gotten:
2834 pte_unmap_unlock(page_table, ptl);
2835
2836 if (unlikely(anon_vma_prepare(vma)))
2837 goto oom;
2838
2839 if (is_zero_pfn(pte_pfn(orig_pte))) {
2840 new_page = alloc_zeroed_user_highpage_movable(vma, address);
2841 if (!new_page)
2842 goto oom;
2843 } else {
2844 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
2845 if (!new_page)
2846 goto oom;
2847 cow_user_page(new_page, old_page, address, vma);
2848 }
2849 __SetPageUptodate(new_page);
2850
2851 if (mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL))
2852 goto oom_free_new;
2853
2854 mmun_start = address & PAGE_MASK;
2855 mmun_end = mmun_start + PAGE_SIZE;
2856 mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
2857
2858 /*
2859 * Re-check the pte - we dropped the lock
2860 */
2861 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
2862 if (likely(pte_same(*page_table, orig_pte))) {
2863 if (old_page) {
2864 if (!PageAnon(old_page)) {
2865 dec_mm_counter_fast(mm, MM_FILEPAGES);
2866 inc_mm_counter_fast(mm, MM_ANONPAGES);
2867 }
2868 } else
2869 inc_mm_counter_fast(mm, MM_ANONPAGES);
2870 flush_cache_page(vma, address, pte_pfn(orig_pte));
2871 entry = mk_pte(new_page, vma->vm_page_prot);
2872 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
2873 /*
2874 * Clear the pte entry and flush it first, before updating the
2875 * pte with the new entry. This will avoid a race condition
2876 * seen in the presence of one thread doing SMC and another
2877 * thread doing COW.
2878 */
2879 ptep_clear_flush(vma, address, page_table);
2880 page_add_new_anon_rmap(new_page, vma, address);
2881 /*
2882 * We call the notify macro here because, when using secondary
2883 * mmu page tables (such as kvm shadow page tables), we want the
2884 * new page to be mapped directly into the secondary page table.
2885 */
2886 set_pte_at_notify(mm, address, page_table, entry);
2887 update_mmu_cache(vma, address, page_table);
2888 if (old_page) {
2889 /*
2890 * Only after switching the pte to the new page may
2891 * we remove the mapcount here. Otherwise another
2892 * process may come and find the rmap count decremented
2893 * before the pte is switched to the new page, and
2894 * "reuse" the old page writing into it while our pte
2895 * here still points into it and can be read by other
2896 * threads.
2897 *
2898 * The critical issue is to order this
2899 * page_remove_rmap with the ptp_clear_flush above.
2900 * Those stores are ordered by (if nothing else,)
2901 * the barrier present in the atomic_add_negative
2902 * in page_remove_rmap.
2903 *
2904 * Then the TLB flush in ptep_clear_flush ensures that
2905 * no process can access the old page before the
2906 * decremented mapcount is visible. And the old page
2907 * cannot be reused until after the decremented
2908 * mapcount is visible. So transitively, TLBs to
2909 * old page will be flushed before it can be reused.
2910 */
2911 page_remove_rmap(old_page);
2912 }
2913
2914 /* Free the old page.. */
2915 new_page = old_page;
2916 ret |= VM_FAULT_WRITE;
2917 } else
2918 mem_cgroup_uncharge_page(new_page);
2919
2920 if (new_page)
2921 page_cache_release(new_page);
2922unlock:
2923 pte_unmap_unlock(page_table, ptl);
2924 if (mmun_end > mmun_start)
2925 mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
2926 if (old_page) {
2927 /*
2928 * Don't let another task, with possibly unlocked vma,
2929 * keep the mlocked page.
2930 */
2931 if ((ret & VM_FAULT_WRITE) && (vma->vm_flags & VM_LOCKED)) {
2932 lock_page(old_page); /* LRU manipulation */
2933 munlock_vma_page(old_page);
2934 unlock_page(old_page);
2935 }
2936 page_cache_release(old_page);
2937 }
2938 return ret;
2939oom_free_new:
2940 page_cache_release(new_page);
2941oom:
2942 if (old_page)
2943 page_cache_release(old_page);
2944 return VM_FAULT_OOM;
2945}
2946
2947static void unmap_mapping_range_vma(struct vm_area_struct *vma,
2948 unsigned long start_addr, unsigned long end_addr,
2949 struct zap_details *details)
2950{
2951 zap_page_range_single(vma, start_addr, end_addr - start_addr, details);
2952}
2953
2954static inline void unmap_mapping_range_tree(struct rb_root *root,
2955 struct zap_details *details)
2956{
2957 struct vm_area_struct *vma;
2958 pgoff_t vba, vea, zba, zea;
2959
2960 vma_interval_tree_foreach(vma, root,
2961 details->first_index, details->last_index) {
2962
2963 vba = vma->vm_pgoff;
2964 vea = vba + vma_pages(vma) - 1;
2965 /* Assume for now that PAGE_CACHE_SHIFT == PAGE_SHIFT */
2966 zba = details->first_index;
2967 if (zba < vba)
2968 zba = vba;
2969 zea = details->last_index;
2970 if (zea > vea)
2971 zea = vea;
2972
2973 unmap_mapping_range_vma(vma,
2974 ((zba - vba) << PAGE_SHIFT) + vma->vm_start,
2975 ((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
2976 details);
2977 }
2978}
2979
2980static inline void unmap_mapping_range_list(struct list_head *head,
2981 struct zap_details *details)
2982{
2983 struct vm_area_struct *vma;
2984
2985 /*
2986 * In nonlinear VMAs there is no correspondence between virtual address
2987 * offset and file offset. So we must perform an exhaustive search
2988 * across *all* the pages in each nonlinear VMA, not just the pages
2989 * whose virtual address lies outside the file truncation point.
2990 */
2991 list_for_each_entry(vma, head, shared.nonlinear) {
2992 details->nonlinear_vma = vma;
2993 unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
2994 }
2995}
2996
2997/**
2998 * unmap_mapping_range - unmap the portion of all mmaps in the specified address_space corresponding to the specified page range in the underlying file.
2999 * @mapping: the address space containing mmaps to be unmapped.
3000 * @holebegin: byte in first page to unmap, relative to the start of
3001 * the underlying file. This will be rounded down to a PAGE_SIZE
3002 * boundary. Note that this is different from truncate_pagecache(), which
3003 * must keep the partial page. In contrast, we must get rid of
3004 * partial pages.
3005 * @holelen: size of prospective hole in bytes. This will be rounded
3006 * up to a PAGE_SIZE boundary. A holelen of zero truncates to the
3007 * end of the file.
3008 * @even_cows: 1 when truncating a file, unmap even private COWed pages;
3009 * but 0 when invalidating pagecache, don't throw away private data.
3010 */
3011void unmap_mapping_range(struct address_space *mapping,
3012 loff_t const holebegin, loff_t const holelen, int even_cows)
3013{
3014 struct zap_details details;
3015 pgoff_t hba = holebegin >> PAGE_SHIFT;
3016 pgoff_t hlen = (holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
3017
3018 /* Check for overflow. */
3019 if (sizeof(holelen) > sizeof(hlen)) {
3020 long long holeend =
3021 (holebegin + holelen + PAGE_SIZE - 1) >> PAGE_SHIFT;
3022 if (holeend & ~(long long)ULONG_MAX)
3023 hlen = ULONG_MAX - hba + 1;
3024 }
3025
3026 details.check_mapping = even_cows? NULL: mapping;
3027 details.nonlinear_vma = NULL;
3028 details.first_index = hba;
3029 details.last_index = hba + hlen - 1;
3030 if (details.last_index < details.first_index)
3031 details.last_index = ULONG_MAX;
3032
3033
3034 mutex_lock(&mapping->i_mmap_mutex);
3035 if (unlikely(!RB_EMPTY_ROOT(&mapping->i_mmap)))
3036 unmap_mapping_range_tree(&mapping->i_mmap, &details);
3037 if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
3038 unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
3039 mutex_unlock(&mapping->i_mmap_mutex);
3040}
3041EXPORT_SYMBOL(unmap_mapping_range);
3042
3043/*
3044 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3045 * but allow concurrent faults), and pte mapped but not yet locked.
3046 * We return with mmap_sem still held, but pte unmapped and unlocked.
3047 */
3048static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
3049 unsigned long address, pte_t *page_table, pmd_t *pmd,
3050 unsigned int flags, pte_t orig_pte)
3051{
3052 spinlock_t *ptl;
3053 struct page *page, *swapcache;
3054 swp_entry_t entry;
3055 pte_t pte;
3056 int locked;
3057 struct mem_cgroup *ptr;
3058 int exclusive = 0;
3059 int ret = 0;
3060
3061 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3062 goto out;
3063
3064 entry = pte_to_swp_entry(orig_pte);
3065 if (unlikely(non_swap_entry(entry))) {
3066 if (is_migration_entry(entry)) {
3067 migration_entry_wait(mm, pmd, address);
3068 } else if (is_hwpoison_entry(entry)) {
3069 ret = VM_FAULT_HWPOISON;
3070 } else {
3071 print_bad_pte(vma, address, orig_pte, NULL);
3072 ret = VM_FAULT_SIGBUS;
3073 }
3074 goto out;
3075 }
3076 delayacct_set_flag(DELAYACCT_PF_SWAPIN);
3077 page = lookup_swap_cache(entry);
3078 if (!page) {
3079 page = swapin_readahead(entry,
3080 GFP_HIGHUSER_MOVABLE, vma, address);
3081 if (!page) {
3082 /*
3083 * Back out if somebody else faulted in this pte
3084 * while we released the pte lock.
3085 */
3086 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3087 if (likely(pte_same(*page_table, orig_pte)))
3088 ret = VM_FAULT_OOM;
3089 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3090 goto unlock;
3091 }
3092
3093 /* Had to read the page from swap area: Major fault */
3094 ret = VM_FAULT_MAJOR;
3095 count_vm_event(PGMAJFAULT);
3096 mem_cgroup_count_vm_event(mm, PGMAJFAULT);
3097 } else if (PageHWPoison(page)) {
3098 /*
3099 * hwpoisoned dirty swapcache pages are kept for killing
3100 * owner processes (which may be unknown at hwpoison time)
3101 */
3102 ret = VM_FAULT_HWPOISON;
3103 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3104 swapcache = page;
3105 goto out_release;
3106 }
3107
3108 swapcache = page;
3109 locked = lock_page_or_retry(page, mm, flags);
3110
3111 delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
3112 if (!locked) {
3113 ret |= VM_FAULT_RETRY;
3114 goto out_release;
3115 }
3116
3117 /*
3118 * Make sure try_to_free_swap or reuse_swap_page or swapoff did not
3119 * release the swapcache from under us. The page pin, and pte_same
3120 * test below, are not enough to exclude that. Even if it is still
3121 * swapcache, we need to check that the page's swap has not changed.
3122 */
3123 if (unlikely(!PageSwapCache(page) || page_private(page) != entry.val))
3124 goto out_page;
3125
3126 page = ksm_might_need_to_copy(page, vma, address);
3127 if (unlikely(!page)) {
3128 ret = VM_FAULT_OOM;
3129 page = swapcache;
3130 goto out_page;
3131 }
3132
3133 if (mem_cgroup_try_charge_swapin(mm, page, GFP_KERNEL, &ptr)) {
3134 ret = VM_FAULT_OOM;
3135 goto out_page;
3136 }
3137
3138 /*
3139 * Back out if somebody else already faulted in this pte.
3140 */
3141 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3142 if (unlikely(!pte_same(*page_table, orig_pte)))
3143 goto out_nomap;
3144
3145 if (unlikely(!PageUptodate(page))) {
3146 ret = VM_FAULT_SIGBUS;
3147 goto out_nomap;
3148 }
3149
3150 /*
3151 * The page isn't present yet, go ahead with the fault.
3152 *
3153 * Be careful about the sequence of operations here.
3154 * To get its accounting right, reuse_swap_page() must be called
3155 * while the page is counted on swap but not yet in mapcount i.e.
3156 * before page_add_anon_rmap() and swap_free(); try_to_free_swap()
3157 * must be called after the swap_free(), or it will never succeed.
3158 * Because delete_from_swap_page() may be called by reuse_swap_page(),
3159 * mem_cgroup_commit_charge_swapin() may not be able to find swp_entry
3160 * in page->private. In this case, a record in swap_cgroup is silently
3161 * discarded at swap_free().
3162 */
3163
3164 inc_mm_counter_fast(mm, MM_ANONPAGES);
3165 dec_mm_counter_fast(mm, MM_SWAPENTS);
3166 pte = mk_pte(page, vma->vm_page_prot);
3167 if ((flags & FAULT_FLAG_WRITE) && reuse_swap_page(page)) {
3168 pte = maybe_mkwrite(pte_mkdirty(pte), vma);
3169 flags &= ~FAULT_FLAG_WRITE;
3170 ret |= VM_FAULT_WRITE;
3171 exclusive = 1;
3172 }
3173 flush_icache_page(vma, page);
3174 if (pte_swp_soft_dirty(orig_pte))
3175 pte = pte_mksoft_dirty(pte);
3176 set_pte_at(mm, address, page_table, pte);
3177 if (page == swapcache)
3178 do_page_add_anon_rmap(page, vma, address, exclusive);
3179 else /* ksm created a completely new copy */
3180 page_add_new_anon_rmap(page, vma, address);
3181 /* It's better to call commit-charge after rmap is established */
3182 mem_cgroup_commit_charge_swapin(page, ptr);
3183
3184 swap_free(entry);
3185 if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
3186 try_to_free_swap(page);
3187 unlock_page(page);
3188 if (page != swapcache) {
3189 /*
3190 * Hold the lock to avoid the swap entry to be reused
3191 * until we take the PT lock for the pte_same() check
3192 * (to avoid false positives from pte_same). For
3193 * further safety release the lock after the swap_free
3194 * so that the swap count won't change under a
3195 * parallel locked swapcache.
3196 */
3197 unlock_page(swapcache);
3198 page_cache_release(swapcache);
3199 }
3200
3201 if (flags & FAULT_FLAG_WRITE) {
3202 ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
3203 if (ret & VM_FAULT_ERROR)
3204 ret &= VM_FAULT_ERROR;
3205 goto out;
3206 }
3207
3208 /* No need to invalidate - it was non-present before */
3209 update_mmu_cache(vma, address, page_table);
3210unlock:
3211 pte_unmap_unlock(page_table, ptl);
3212out:
3213 return ret;
3214out_nomap:
3215 mem_cgroup_cancel_charge_swapin(ptr);
3216 pte_unmap_unlock(page_table, ptl);
3217out_page:
3218 unlock_page(page);
3219out_release:
3220 page_cache_release(page);
3221 if (page != swapcache) {
3222 unlock_page(swapcache);
3223 page_cache_release(swapcache);
3224 }
3225 return ret;
3226}
3227
3228/*
3229 * This is like a special single-page "expand_{down|up}wards()",
3230 * except we must first make sure that 'address{-|+}PAGE_SIZE'
3231 * doesn't hit another vma.
3232 */
3233static inline int check_stack_guard_page(struct vm_area_struct *vma, unsigned long address)
3234{
3235 address &= PAGE_MASK;
3236 if ((vma->vm_flags & VM_GROWSDOWN) && address == vma->vm_start) {
3237 struct vm_area_struct *prev = vma->vm_prev;
3238
3239 /*
3240 * Is there a mapping abutting this one below?
3241 *
3242 * That's only ok if it's the same stack mapping
3243 * that has gotten split..
3244 */
3245 if (prev && prev->vm_end == address)
3246 return prev->vm_flags & VM_GROWSDOWN ? 0 : -ENOMEM;
3247
3248 expand_downwards(vma, address - PAGE_SIZE);
3249 }
3250 if ((vma->vm_flags & VM_GROWSUP) && address + PAGE_SIZE == vma->vm_end) {
3251 struct vm_area_struct *next = vma->vm_next;
3252
3253 /* As VM_GROWSDOWN but s/below/above/ */
3254 if (next && next->vm_start == address + PAGE_SIZE)
3255 return next->vm_flags & VM_GROWSUP ? 0 : -ENOMEM;
3256
3257 expand_upwards(vma, address + PAGE_SIZE);
3258 }
3259 return 0;
3260}
3261
3262/*
3263 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3264 * but allow concurrent faults), and pte mapped but not yet locked.
3265 * We return with mmap_sem still held, but pte unmapped and unlocked.
3266 */
3267static int do_anonymous_page(struct mm_struct *mm, struct vm_area_struct *vma,
3268 unsigned long address, pte_t *page_table, pmd_t *pmd,
3269 unsigned int flags)
3270{
3271 struct page *page;
3272 spinlock_t *ptl;
3273 pte_t entry;
3274
3275 pte_unmap(page_table);
3276
3277 /* Check if we need to add a guard page to the stack */
3278 if (check_stack_guard_page(vma, address) < 0)
3279 return VM_FAULT_SIGBUS;
3280
3281 /* Use the zero-page for reads */
3282 if (!(flags & FAULT_FLAG_WRITE)) {
3283 entry = pte_mkspecial(pfn_pte(my_zero_pfn(address),
3284 vma->vm_page_prot));
3285 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3286 if (!pte_none(*page_table))
3287 goto unlock;
3288 goto setpte;
3289 }
3290
3291 /* Allocate our own private page. */
3292 if (unlikely(anon_vma_prepare(vma)))
3293 goto oom;
3294 page = alloc_zeroed_user_highpage_movable(vma, address);
3295 if (!page)
3296 goto oom;
3297 /*
3298 * The memory barrier inside __SetPageUptodate makes sure that
3299 * preceeding stores to the page contents become visible before
3300 * the set_pte_at() write.
3301 */
3302 __SetPageUptodate(page);
3303
3304 if (mem_cgroup_charge_anon(page, mm, GFP_KERNEL))
3305 goto oom_free_page;
3306
3307 entry = mk_pte(page, vma->vm_page_prot);
3308 if (vma->vm_flags & VM_WRITE)
3309 entry = pte_mkwrite(pte_mkdirty(entry));
3310
3311 page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
3312 if (!pte_none(*page_table))
3313 goto release;
3314
3315 inc_mm_counter_fast(mm, MM_ANONPAGES);
3316 page_add_new_anon_rmap(page, vma, address);
3317setpte:
3318 set_pte_at(mm, address, page_table, entry);
3319
3320 /* No need to invalidate - it was non-present before */
3321 update_mmu_cache(vma, address, page_table);
3322unlock:
3323 pte_unmap_unlock(page_table, ptl);
3324 return 0;
3325release:
3326 mem_cgroup_uncharge_page(page);
3327 page_cache_release(page);
3328 goto unlock;
3329oom_free_page:
3330 page_cache_release(page);
3331oom:
3332 return VM_FAULT_OOM;
3333}
3334
3335static int __do_fault(struct vm_area_struct *vma, unsigned long address,
3336 pgoff_t pgoff, unsigned int flags, struct page **page)
3337{
3338 struct vm_fault vmf;
3339 int ret;
3340
3341 vmf.virtual_address = (void __user *)(address & PAGE_MASK);
3342 vmf.pgoff = pgoff;
3343 vmf.flags = flags;
3344 vmf.page = NULL;
3345
3346 ret = vma->vm_ops->fault(vma, &vmf);
3347 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3348 return ret;
3349
3350 if (unlikely(PageHWPoison(vmf.page))) {
3351 if (ret & VM_FAULT_LOCKED)
3352 unlock_page(vmf.page);
3353 page_cache_release(vmf.page);
3354 return VM_FAULT_HWPOISON;
3355 }
3356
3357 if (unlikely(!(ret & VM_FAULT_LOCKED)))
3358 lock_page(vmf.page);
3359 else
3360 VM_BUG_ON_PAGE(!PageLocked(vmf.page), vmf.page);
3361
3362 *page = vmf.page;
3363 return ret;
3364}
3365
3366/**
3367 * do_set_pte - setup new PTE entry for given page and add reverse page mapping.
3368 *
3369 * @vma: virtual memory area
3370 * @address: user virtual address
3371 * @page: page to map
3372 * @pte: pointer to target page table entry
3373 * @write: true, if new entry is writable
3374 * @anon: true, if it's anonymous page
3375 *
3376 * Caller must hold page table lock relevant for @pte.
3377 *
3378 * Target users are page handler itself and implementations of
3379 * vm_ops->map_pages.
3380 */
3381void do_set_pte(struct vm_area_struct *vma, unsigned long address,
3382 struct page *page, pte_t *pte, bool write, bool anon)
3383{
3384 pte_t entry;
3385
3386 flush_icache_page(vma, page);
3387 entry = mk_pte(page, vma->vm_page_prot);
3388 if (write)
3389 entry = maybe_mkwrite(pte_mkdirty(entry), vma);
3390 else if (pte_file(*pte) && pte_file_soft_dirty(*pte))
3391 pte_mksoft_dirty(entry);
3392 if (anon) {
3393 inc_mm_counter_fast(vma->vm_mm, MM_ANONPAGES);
3394 page_add_new_anon_rmap(page, vma, address);
3395 } else {
3396 inc_mm_counter_fast(vma->vm_mm, MM_FILEPAGES);
3397 page_add_file_rmap(page);
3398 }
3399 set_pte_at(vma->vm_mm, address, pte, entry);
3400
3401 /* no need to invalidate: a not-present page won't be cached */
3402 update_mmu_cache(vma, address, pte);
3403}
3404
3405#define FAULT_AROUND_ORDER 4
3406
3407#ifdef CONFIG_DEBUG_FS
3408static unsigned int fault_around_order = FAULT_AROUND_ORDER;
3409
3410static int fault_around_order_get(void *data, u64 *val)
3411{
3412 *val = fault_around_order;
3413 return 0;
3414}
3415
3416static int fault_around_order_set(void *data, u64 val)
3417{
3418 BUILD_BUG_ON((1UL << FAULT_AROUND_ORDER) > PTRS_PER_PTE);
3419 if (1UL << val > PTRS_PER_PTE)
3420 return -EINVAL;
3421 fault_around_order = val;
3422 return 0;
3423}
3424DEFINE_SIMPLE_ATTRIBUTE(fault_around_order_fops,
3425 fault_around_order_get, fault_around_order_set, "%llu\n");
3426
3427static int __init fault_around_debugfs(void)
3428{
3429 void *ret;
3430
3431 ret = debugfs_create_file("fault_around_order", 0644, NULL, NULL,
3432 &fault_around_order_fops);
3433 if (!ret)
3434 pr_warn("Failed to create fault_around_order in debugfs");
3435 return 0;
3436}
3437late_initcall(fault_around_debugfs);
3438
3439static inline unsigned long fault_around_pages(void)
3440{
3441 return 1UL << fault_around_order;
3442}
3443
3444static inline unsigned long fault_around_mask(void)
3445{
3446 return ~((1UL << (PAGE_SHIFT + fault_around_order)) - 1);
3447}
3448#else
3449static inline unsigned long fault_around_pages(void)
3450{
3451 unsigned long nr_pages;
3452
3453 nr_pages = 1UL << FAULT_AROUND_ORDER;
3454 BUILD_BUG_ON(nr_pages > PTRS_PER_PTE);
3455 return nr_pages;
3456}
3457
3458static inline unsigned long fault_around_mask(void)
3459{
3460 return ~((1UL << (PAGE_SHIFT + FAULT_AROUND_ORDER)) - 1);
3461}
3462#endif
3463
3464static void do_fault_around(struct vm_area_struct *vma, unsigned long address,
3465 pte_t *pte, pgoff_t pgoff, unsigned int flags)
3466{
3467 unsigned long start_addr;
3468 pgoff_t max_pgoff;
3469 struct vm_fault vmf;
3470 int off;
3471
3472 start_addr = max(address & fault_around_mask(), vma->vm_start);
3473 off = ((address - start_addr) >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
3474 pte -= off;
3475 pgoff -= off;
3476
3477 /*
3478 * max_pgoff is either end of page table or end of vma
3479 * or fault_around_pages() from pgoff, depending what is neast.
3480 */
3481 max_pgoff = pgoff - ((start_addr >> PAGE_SHIFT) & (PTRS_PER_PTE - 1)) +
3482 PTRS_PER_PTE - 1;
3483 max_pgoff = min3(max_pgoff, vma_pages(vma) + vma->vm_pgoff - 1,
3484 pgoff + fault_around_pages() - 1);
3485
3486 /* Check if it makes any sense to call ->map_pages */
3487 while (!pte_none(*pte)) {
3488 if (++pgoff > max_pgoff)
3489 return;
3490 start_addr += PAGE_SIZE;
3491 if (start_addr >= vma->vm_end)
3492 return;
3493 pte++;
3494 }
3495
3496 vmf.virtual_address = (void __user *) start_addr;
3497 vmf.pte = pte;
3498 vmf.pgoff = pgoff;
3499 vmf.max_pgoff = max_pgoff;
3500 vmf.flags = flags;
3501 vma->vm_ops->map_pages(vma, &vmf);
3502}
3503
3504static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3505 unsigned long address, pmd_t *pmd,
3506 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3507{
3508 struct page *fault_page;
3509 spinlock_t *ptl;
3510 pte_t *pte;
3511 int ret = 0;
3512
3513 /*
3514 * Let's call ->map_pages() first and use ->fault() as fallback
3515 * if page by the offset is not ready to be mapped (cold cache or
3516 * something).
3517 */
3518 if (vma->vm_ops->map_pages) {
3519 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
3520 do_fault_around(vma, address, pte, pgoff, flags);
3521 if (!pte_same(*pte, orig_pte))
3522 goto unlock_out;
3523 pte_unmap_unlock(pte, ptl);
3524 }
3525
3526 ret = __do_fault(vma, address, pgoff, flags, &fault_page);
3527 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3528 return ret;
3529
3530 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
3531 if (unlikely(!pte_same(*pte, orig_pte))) {
3532 pte_unmap_unlock(pte, ptl);
3533 unlock_page(fault_page);
3534 page_cache_release(fault_page);
3535 return ret;
3536 }
3537 do_set_pte(vma, address, fault_page, pte, false, false);
3538 unlock_page(fault_page);
3539unlock_out:
3540 pte_unmap_unlock(pte, ptl);
3541 return ret;
3542}
3543
3544static int do_cow_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3545 unsigned long address, pmd_t *pmd,
3546 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3547{
3548 struct page *fault_page, *new_page;
3549 spinlock_t *ptl;
3550 pte_t *pte;
3551 int ret;
3552
3553 if (unlikely(anon_vma_prepare(vma)))
3554 return VM_FAULT_OOM;
3555
3556 new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
3557 if (!new_page)
3558 return VM_FAULT_OOM;
3559
3560 if (mem_cgroup_charge_anon(new_page, mm, GFP_KERNEL)) {
3561 page_cache_release(new_page);
3562 return VM_FAULT_OOM;
3563 }
3564
3565 ret = __do_fault(vma, address, pgoff, flags, &fault_page);
3566 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3567 goto uncharge_out;
3568
3569 copy_user_highpage(new_page, fault_page, address, vma);
3570 __SetPageUptodate(new_page);
3571
3572 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
3573 if (unlikely(!pte_same(*pte, orig_pte))) {
3574 pte_unmap_unlock(pte, ptl);
3575 unlock_page(fault_page);
3576 page_cache_release(fault_page);
3577 goto uncharge_out;
3578 }
3579 do_set_pte(vma, address, new_page, pte, true, true);
3580 pte_unmap_unlock(pte, ptl);
3581 unlock_page(fault_page);
3582 page_cache_release(fault_page);
3583 return ret;
3584uncharge_out:
3585 mem_cgroup_uncharge_page(new_page);
3586 page_cache_release(new_page);
3587 return ret;
3588}
3589
3590static int do_shared_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3591 unsigned long address, pmd_t *pmd,
3592 pgoff_t pgoff, unsigned int flags, pte_t orig_pte)
3593{
3594 struct page *fault_page;
3595 struct address_space *mapping;
3596 spinlock_t *ptl;
3597 pte_t *pte;
3598 int dirtied = 0;
3599 int ret, tmp;
3600
3601 ret = __do_fault(vma, address, pgoff, flags, &fault_page);
3602 if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE | VM_FAULT_RETRY)))
3603 return ret;
3604
3605 /*
3606 * Check if the backing address space wants to know that the page is
3607 * about to become writable
3608 */
3609 if (vma->vm_ops->page_mkwrite) {
3610 unlock_page(fault_page);
3611 tmp = do_page_mkwrite(vma, fault_page, address);
3612 if (unlikely(!tmp ||
3613 (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) {
3614 page_cache_release(fault_page);
3615 return tmp;
3616 }
3617 }
3618
3619 pte = pte_offset_map_lock(mm, pmd, address, &ptl);
3620 if (unlikely(!pte_same(*pte, orig_pte))) {
3621 pte_unmap_unlock(pte, ptl);
3622 unlock_page(fault_page);
3623 page_cache_release(fault_page);
3624 return ret;
3625 }
3626 do_set_pte(vma, address, fault_page, pte, true, false);
3627 pte_unmap_unlock(pte, ptl);
3628
3629 if (set_page_dirty(fault_page))
3630 dirtied = 1;
3631 mapping = fault_page->mapping;
3632 unlock_page(fault_page);
3633 if ((dirtied || vma->vm_ops->page_mkwrite) && mapping) {
3634 /*
3635 * Some device drivers do not set page.mapping but still
3636 * dirty their pages
3637 */
3638 balance_dirty_pages_ratelimited(mapping);
3639 }
3640
3641 /* file_update_time outside page_lock */
3642 if (vma->vm_file && !vma->vm_ops->page_mkwrite)
3643 file_update_time(vma->vm_file);
3644
3645 return ret;
3646}
3647
3648static int do_linear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3649 unsigned long address, pte_t *page_table, pmd_t *pmd,
3650 unsigned int flags, pte_t orig_pte)
3651{
3652 pgoff_t pgoff = (((address & PAGE_MASK)
3653 - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
3654
3655 pte_unmap(page_table);
3656 if (!(flags & FAULT_FLAG_WRITE))
3657 return do_read_fault(mm, vma, address, pmd, pgoff, flags,
3658 orig_pte);
3659 if (!(vma->vm_flags & VM_SHARED))
3660 return do_cow_fault(mm, vma, address, pmd, pgoff, flags,
3661 orig_pte);
3662 return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3663}
3664
3665/*
3666 * Fault of a previously existing named mapping. Repopulate the pte
3667 * from the encoded file_pte if possible. This enables swappable
3668 * nonlinear vmas.
3669 *
3670 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3671 * but allow concurrent faults), and pte mapped but not yet locked.
3672 * We return with mmap_sem still held, but pte unmapped and unlocked.
3673 */
3674static int do_nonlinear_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3675 unsigned long address, pte_t *page_table, pmd_t *pmd,
3676 unsigned int flags, pte_t orig_pte)
3677{
3678 pgoff_t pgoff;
3679
3680 flags |= FAULT_FLAG_NONLINEAR;
3681
3682 if (!pte_unmap_same(mm, pmd, page_table, orig_pte))
3683 return 0;
3684
3685 if (unlikely(!(vma->vm_flags & VM_NONLINEAR))) {
3686 /*
3687 * Page table corrupted: show pte and kill process.
3688 */
3689 print_bad_pte(vma, address, orig_pte, NULL);
3690 return VM_FAULT_SIGBUS;
3691 }
3692
3693 pgoff = pte_to_pgoff(orig_pte);
3694 if (!(flags & FAULT_FLAG_WRITE))
3695 return do_read_fault(mm, vma, address, pmd, pgoff, flags,
3696 orig_pte);
3697 if (!(vma->vm_flags & VM_SHARED))
3698 return do_cow_fault(mm, vma, address, pmd, pgoff, flags,
3699 orig_pte);
3700 return do_shared_fault(mm, vma, address, pmd, pgoff, flags, orig_pte);
3701}
3702
3703static int numa_migrate_prep(struct page *page, struct vm_area_struct *vma,
3704 unsigned long addr, int page_nid,
3705 int *flags)
3706{
3707 get_page(page);
3708
3709 count_vm_numa_event(NUMA_HINT_FAULTS);
3710 if (page_nid == numa_node_id()) {
3711 count_vm_numa_event(NUMA_HINT_FAULTS_LOCAL);
3712 *flags |= TNF_FAULT_LOCAL;
3713 }
3714
3715 return mpol_misplaced(page, vma, addr);
3716}
3717
3718static int do_numa_page(struct mm_struct *mm, struct vm_area_struct *vma,
3719 unsigned long addr, pte_t pte, pte_t *ptep, pmd_t *pmd)
3720{
3721 struct page *page = NULL;
3722 spinlock_t *ptl;
3723 int page_nid = -1;
3724 int last_cpupid;
3725 int target_nid;
3726 bool migrated = false;
3727 int flags = 0;
3728
3729 /*
3730 * The "pte" at this point cannot be used safely without
3731 * validation through pte_unmap_same(). It's of NUMA type but
3732 * the pfn may be screwed if the read is non atomic.
3733 *
3734 * ptep_modify_prot_start is not called as this is clearing
3735 * the _PAGE_NUMA bit and it is not really expected that there
3736 * would be concurrent hardware modifications to the PTE.
3737 */
3738 ptl = pte_lockptr(mm, pmd);
3739 spin_lock(ptl);
3740 if (unlikely(!pte_same(*ptep, pte))) {
3741 pte_unmap_unlock(ptep, ptl);
3742 goto out;
3743 }
3744
3745 pte = pte_mknonnuma(pte);
3746 set_pte_at(mm, addr, ptep, pte);
3747 update_mmu_cache(vma, addr, ptep);
3748
3749 page = vm_normal_page(vma, addr, pte);
3750 if (!page) {
3751 pte_unmap_unlock(ptep, ptl);
3752 return 0;
3753 }
3754 BUG_ON(is_zero_pfn(page_to_pfn(page)));
3755
3756 /*
3757 * Avoid grouping on DSO/COW pages in specific and RO pages
3758 * in general, RO pages shouldn't hurt as much anyway since
3759 * they can be in shared cache state.
3760 */
3761 if (!pte_write(pte))
3762 flags |= TNF_NO_GROUP;
3763
3764 /*
3765 * Flag if the page is shared between multiple address spaces. This
3766 * is later used when determining whether to group tasks together
3767 */
3768 if (page_mapcount(page) > 1 && (vma->vm_flags & VM_SHARED))
3769 flags |= TNF_SHARED;
3770
3771 last_cpupid = page_cpupid_last(page);
3772 page_nid = page_to_nid(page);
3773 target_nid = numa_migrate_prep(page, vma, addr, page_nid, &flags);
3774 pte_unmap_unlock(ptep, ptl);
3775 if (target_nid == -1) {
3776 put_page(page);
3777 goto out;
3778 }
3779
3780 /* Migrate to the requested node */
3781 migrated = migrate_misplaced_page(page, vma, target_nid);
3782 if (migrated) {
3783 page_nid = target_nid;
3784 flags |= TNF_MIGRATED;
3785 }
3786
3787out:
3788 if (page_nid != -1)
3789 task_numa_fault(last_cpupid, page_nid, 1, flags);
3790 return 0;
3791}
3792
3793/*
3794 * These routines also need to handle stuff like marking pages dirty
3795 * and/or accessed for architectures that don't do it in hardware (most
3796 * RISC architectures). The early dirtying is also good on the i386.
3797 *
3798 * There is also a hook called "update_mmu_cache()" that architectures
3799 * with external mmu caches can use to update those (ie the Sparc or
3800 * PowerPC hashed page tables that act as extended TLBs).
3801 *
3802 * We enter with non-exclusive mmap_sem (to exclude vma changes,
3803 * but allow concurrent faults), and pte mapped but not yet locked.
3804 * We return with mmap_sem still held, but pte unmapped and unlocked.
3805 */
3806static int handle_pte_fault(struct mm_struct *mm,
3807 struct vm_area_struct *vma, unsigned long address,
3808 pte_t *pte, pmd_t *pmd, unsigned int flags)
3809{
3810 pte_t entry;
3811 spinlock_t *ptl;
3812
3813 entry = *pte;
3814 if (!pte_present(entry)) {
3815 if (pte_none(entry)) {
3816 if (vma->vm_ops) {
3817 if (likely(vma->vm_ops->fault))
3818 return do_linear_fault(mm, vma, address,
3819 pte, pmd, flags, entry);
3820 }
3821 return do_anonymous_page(mm, vma, address,
3822 pte, pmd, flags);
3823 }
3824 if (pte_file(entry))
3825 return do_nonlinear_fault(mm, vma, address,
3826 pte, pmd, flags, entry);
3827 return do_swap_page(mm, vma, address,
3828 pte, pmd, flags, entry);
3829 }
3830
3831 if (pte_numa(entry))
3832 return do_numa_page(mm, vma, address, entry, pte, pmd);
3833
3834 ptl = pte_lockptr(mm, pmd);
3835 spin_lock(ptl);
3836 if (unlikely(!pte_same(*pte, entry)))
3837 goto unlock;
3838 if (flags & FAULT_FLAG_WRITE) {
3839 if (!pte_write(entry))
3840 return do_wp_page(mm, vma, address,
3841 pte, pmd, ptl, entry);
3842 entry = pte_mkdirty(entry);
3843 }
3844 entry = pte_mkyoung(entry);
3845 if (ptep_set_access_flags(vma, address, pte, entry, flags & FAULT_FLAG_WRITE)) {
3846 update_mmu_cache(vma, address, pte);
3847 } else {
3848 /*
3849 * This is needed only for protection faults but the arch code
3850 * is not yet telling us if this is a protection fault or not.
3851 * This still avoids useless tlb flushes for .text page faults
3852 * with threads.
3853 */
3854 if (flags & FAULT_FLAG_WRITE)
3855 flush_tlb_fix_spurious_fault(vma, address);
3856 }
3857unlock:
3858 pte_unmap_unlock(pte, ptl);
3859 return 0;
3860}
3861
3862/*
3863 * By the time we get here, we already hold the mm semaphore
3864 */
3865static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3866 unsigned long address, unsigned int flags)
3867{
3868 pgd_t *pgd;
3869 pud_t *pud;
3870 pmd_t *pmd;
3871 pte_t *pte;
3872
3873 if (unlikely(is_vm_hugetlb_page(vma)))
3874 return hugetlb_fault(mm, vma, address, flags);
3875
3876 pgd = pgd_offset(mm, address);
3877 pud = pud_alloc(mm, pgd, address);
3878 if (!pud)
3879 return VM_FAULT_OOM;
3880 pmd = pmd_alloc(mm, pud, address);
3881 if (!pmd)
3882 return VM_FAULT_OOM;
3883 if (pmd_none(*pmd) && transparent_hugepage_enabled(vma)) {
3884 int ret = VM_FAULT_FALLBACK;
3885 if (!vma->vm_ops)
3886 ret = do_huge_pmd_anonymous_page(mm, vma, address,
3887 pmd, flags);
3888 if (!(ret & VM_FAULT_FALLBACK))
3889 return ret;
3890 } else {
3891 pmd_t orig_pmd = *pmd;
3892 int ret;
3893
3894 barrier();
3895 if (pmd_trans_huge(orig_pmd)) {
3896 unsigned int dirty = flags & FAULT_FLAG_WRITE;
3897
3898 /*
3899 * If the pmd is splitting, return and retry the
3900 * the fault. Alternative: wait until the split
3901 * is done, and goto retry.
3902 */
3903 if (pmd_trans_splitting(orig_pmd))
3904 return 0;
3905
3906 if (pmd_numa(orig_pmd))
3907 return do_huge_pmd_numa_page(mm, vma, address,
3908 orig_pmd, pmd);
3909
3910 if (dirty && !pmd_write(orig_pmd)) {
3911 ret = do_huge_pmd_wp_page(mm, vma, address, pmd,
3912 orig_pmd);
3913 if (!(ret & VM_FAULT_FALLBACK))
3914 return ret;
3915 } else {
3916 huge_pmd_set_accessed(mm, vma, address, pmd,
3917 orig_pmd, dirty);
3918 return 0;
3919 }
3920 }
3921 }
3922
3923 /* THP should already have been handled */
3924 BUG_ON(pmd_numa(*pmd));
3925
3926 /*
3927 * Use __pte_alloc instead of pte_alloc_map, because we can't
3928 * run pte_offset_map on the pmd, if an huge pmd could
3929 * materialize from under us from a different thread.
3930 */
3931 if (unlikely(pmd_none(*pmd)) &&
3932 unlikely(__pte_alloc(mm, vma, pmd, address)))
3933 return VM_FAULT_OOM;
3934 /* if an huge pmd materialized from under us just retry later */
3935 if (unlikely(pmd_trans_huge(*pmd)))
3936 return 0;
3937 /*
3938 * A regular pmd is established and it can't morph into a huge pmd
3939 * from under us anymore at this point because we hold the mmap_sem
3940 * read mode and khugepaged takes it in write mode. So now it's
3941 * safe to run pte_offset_map().
3942 */
3943 pte = pte_offset_map(pmd, address);
3944
3945 return handle_pte_fault(mm, vma, address, pte, pmd, flags);
3946}
3947
3948int handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma,
3949 unsigned long address, unsigned int flags)
3950{
3951 int ret;
3952
3953 __set_current_state(TASK_RUNNING);
3954
3955 count_vm_event(PGFAULT);
3956 mem_cgroup_count_vm_event(mm, PGFAULT);
3957
3958 /* do counter updates before entering really critical section. */
3959 check_sync_rss_stat(current);
3960
3961 /*
3962 * Enable the memcg OOM handling for faults triggered in user
3963 * space. Kernel faults are handled more gracefully.
3964 */
3965 if (flags & FAULT_FLAG_USER)
3966 mem_cgroup_oom_enable();
3967
3968 ret = __handle_mm_fault(mm, vma, address, flags);
3969
3970 if (flags & FAULT_FLAG_USER) {
3971 mem_cgroup_oom_disable();
3972 /*
3973 * The task may have entered a memcg OOM situation but
3974 * if the allocation error was handled gracefully (no
3975 * VM_FAULT_OOM), there is no need to kill anything.
3976 * Just clean up the OOM state peacefully.
3977 */
3978 if (task_in_memcg_oom(current) && !(ret & VM_FAULT_OOM))
3979 mem_cgroup_oom_synchronize(false);
3980 }
3981
3982 return ret;
3983}
3984
3985#ifndef __PAGETABLE_PUD_FOLDED
3986/*
3987 * Allocate page upper directory.
3988 * We've already handled the fast-path in-line.
3989 */
3990int __pud_alloc(struct mm_struct *mm, pgd_t *pgd, unsigned long address)
3991{
3992 pud_t *new = pud_alloc_one(mm, address);
3993 if (!new)
3994 return -ENOMEM;
3995
3996 smp_wmb(); /* See comment in __pte_alloc */
3997
3998 spin_lock(&mm->page_table_lock);
3999 if (pgd_present(*pgd)) /* Another has populated it */
4000 pud_free(mm, new);
4001 else
4002 pgd_populate(mm, pgd, new);
4003 spin_unlock(&mm->page_table_lock);
4004 return 0;
4005}
4006#endif /* __PAGETABLE_PUD_FOLDED */
4007
4008#ifndef __PAGETABLE_PMD_FOLDED
4009/*
4010 * Allocate page middle directory.
4011 * We've already handled the fast-path in-line.
4012 */
4013int __pmd_alloc(struct mm_struct *mm, pud_t *pud, unsigned long address)
4014{
4015 pmd_t *new = pmd_alloc_one(mm, address);
4016 if (!new)
4017 return -ENOMEM;
4018
4019 smp_wmb(); /* See comment in __pte_alloc */
4020
4021 spin_lock(&mm->page_table_lock);
4022#ifndef __ARCH_HAS_4LEVEL_HACK
4023 if (pud_present(*pud)) /* Another has populated it */
4024 pmd_free(mm, new);
4025 else
4026 pud_populate(mm, pud, new);
4027#else
4028 if (pgd_present(*pud)) /* Another has populated it */
4029 pmd_free(mm, new);
4030 else
4031 pgd_populate(mm, pud, new);
4032#endif /* __ARCH_HAS_4LEVEL_HACK */
4033 spin_unlock(&mm->page_table_lock);
4034 return 0;
4035}
4036#endif /* __PAGETABLE_PMD_FOLDED */
4037
4038#if !defined(__HAVE_ARCH_GATE_AREA)
4039
4040#if defined(AT_SYSINFO_EHDR)
4041static struct vm_area_struct gate_vma;
4042
4043static int __init gate_vma_init(void)
4044{
4045 gate_vma.vm_mm = NULL;
4046 gate_vma.vm_start = FIXADDR_USER_START;
4047 gate_vma.vm_end = FIXADDR_USER_END;
4048 gate_vma.vm_flags = VM_READ | VM_MAYREAD | VM_EXEC | VM_MAYEXEC;
4049 gate_vma.vm_page_prot = __P101;
4050
4051 return 0;
4052}
4053__initcall(gate_vma_init);
4054#endif
4055
4056struct vm_area_struct *get_gate_vma(struct mm_struct *mm)
4057{
4058#ifdef AT_SYSINFO_EHDR
4059 return &gate_vma;
4060#else
4061 return NULL;
4062#endif
4063}
4064
4065int in_gate_area_no_mm(unsigned long addr)
4066{
4067#ifdef AT_SYSINFO_EHDR
4068 if ((addr >= FIXADDR_USER_START) && (addr < FIXADDR_USER_END))
4069 return 1;
4070#endif
4071 return 0;
4072}
4073
4074#endif /* __HAVE_ARCH_GATE_AREA */
4075
4076static int __follow_pte(struct mm_struct *mm, unsigned long address,
4077 pte_t **ptepp, spinlock_t **ptlp)
4078{
4079 pgd_t *pgd;
4080 pud_t *pud;
4081 pmd_t *pmd;
4082 pte_t *ptep;
4083
4084 pgd = pgd_offset(mm, address);
4085 if (pgd_none(*pgd) || unlikely(pgd_bad(*pgd)))
4086 goto out;
4087
4088 pud = pud_offset(pgd, address);
4089 if (pud_none(*pud) || unlikely(pud_bad(*pud)))
4090 goto out;
4091
4092 pmd = pmd_offset(pud, address);
4093 VM_BUG_ON(pmd_trans_huge(*pmd));
4094 if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
4095 goto out;
4096
4097 /* We cannot handle huge page PFN maps. Luckily they don't exist. */
4098 if (pmd_huge(*pmd))
4099 goto out;
4100
4101 ptep = pte_offset_map_lock(mm, pmd, address, ptlp);
4102 if (!ptep)
4103 goto out;
4104 if (!pte_present(*ptep))
4105 goto unlock;
4106 *ptepp = ptep;
4107 return 0;
4108unlock:
4109 pte_unmap_unlock(ptep, *ptlp);
4110out:
4111 return -EINVAL;
4112}
4113
4114static inline int follow_pte(struct mm_struct *mm, unsigned long address,
4115 pte_t **ptepp, spinlock_t **ptlp)
4116{
4117 int res;
4118
4119 /* (void) is needed to make gcc happy */
4120 (void) __cond_lock(*ptlp,
4121 !(res = __follow_pte(mm, address, ptepp, ptlp)));
4122 return res;
4123}
4124
4125/**
4126 * follow_pfn - look up PFN at a user virtual address
4127 * @vma: memory mapping
4128 * @address: user virtual address
4129 * @pfn: location to store found PFN
4130 *
4131 * Only IO mappings and raw PFN mappings are allowed.
4132 *
4133 * Returns zero and the pfn at @pfn on success, -ve otherwise.
4134 */
4135int follow_pfn(struct vm_area_struct *vma, unsigned long address,
4136 unsigned long *pfn)
4137{
4138 int ret = -EINVAL;
4139 spinlock_t *ptl;
4140 pte_t *ptep;
4141
4142 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4143 return ret;
4144
4145 ret = follow_pte(vma->vm_mm, address, &ptep, &ptl);
4146 if (ret)
4147 return ret;
4148 *pfn = pte_pfn(*ptep);
4149 pte_unmap_unlock(ptep, ptl);
4150 return 0;
4151}
4152EXPORT_SYMBOL(follow_pfn);
4153
4154#ifdef CONFIG_HAVE_IOREMAP_PROT
4155int follow_phys(struct vm_area_struct *vma,
4156 unsigned long address, unsigned int flags,
4157 unsigned long *prot, resource_size_t *phys)
4158{
4159 int ret = -EINVAL;
4160 pte_t *ptep, pte;
4161 spinlock_t *ptl;
4162
4163 if (!(vma->vm_flags & (VM_IO | VM_PFNMAP)))
4164 goto out;
4165
4166 if (follow_pte(vma->vm_mm, address, &ptep, &ptl))
4167 goto out;
4168 pte = *ptep;
4169
4170 if ((flags & FOLL_WRITE) && !pte_write(pte))
4171 goto unlock;
4172
4173 *prot = pgprot_val(pte_pgprot(pte));
4174 *phys = (resource_size_t)pte_pfn(pte) << PAGE_SHIFT;
4175
4176 ret = 0;
4177unlock:
4178 pte_unmap_unlock(ptep, ptl);
4179out:
4180 return ret;
4181}
4182
4183int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
4184 void *buf, int len, int write)
4185{
4186 resource_size_t phys_addr;
4187 unsigned long prot = 0;
4188 void __iomem *maddr;
4189 int offset = addr & (PAGE_SIZE-1);
4190
4191 if (follow_phys(vma, addr, write, &prot, &phys_addr))
4192 return -EINVAL;
4193
4194 maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
4195 if (write)
4196 memcpy_toio(maddr + offset, buf, len);
4197 else
4198 memcpy_fromio(buf, maddr + offset, len);
4199 iounmap(maddr);
4200
4201 return len;
4202}
4203EXPORT_SYMBOL_GPL(generic_access_phys);
4204#endif
4205
4206/*
4207 * Access another process' address space as given in mm. If non-NULL, use the
4208 * given task for page fault accounting.
4209 */
4210static int __access_remote_vm(struct task_struct *tsk, struct mm_struct *mm,
4211 unsigned long addr, void *buf, int len, int write)
4212{
4213 struct vm_area_struct *vma;
4214 void *old_buf = buf;
4215
4216 down_read(&mm->mmap_sem);
4217 /* ignore errors, just check how much was successfully transferred */
4218 while (len) {
4219 int bytes, ret, offset;
4220 void *maddr;
4221 struct page *page = NULL;
4222
4223 ret = get_user_pages(tsk, mm, addr, 1,
4224 write, 1, &page, &vma);
4225 if (ret <= 0) {
4226 /*
4227 * Check if this is a VM_IO | VM_PFNMAP VMA, which
4228 * we can access using slightly different code.
4229 */
4230#ifdef CONFIG_HAVE_IOREMAP_PROT
4231 vma = find_vma(mm, addr);
4232 if (!vma || vma->vm_start > addr)
4233 break;
4234 if (vma->vm_ops && vma->vm_ops->access)
4235 ret = vma->vm_ops->access(vma, addr, buf,
4236 len, write);
4237 if (ret <= 0)
4238#endif
4239 break;
4240 bytes = ret;
4241 } else {
4242 bytes = len;
4243 offset = addr & (PAGE_SIZE-1);
4244 if (bytes > PAGE_SIZE-offset)
4245 bytes = PAGE_SIZE-offset;
4246
4247 maddr = kmap(page);
4248 if (write) {
4249 copy_to_user_page(vma, page, addr,
4250 maddr + offset, buf, bytes);
4251 set_page_dirty_lock(page);
4252 } else {
4253 copy_from_user_page(vma, page, addr,
4254 buf, maddr + offset, bytes);
4255 }
4256 kunmap(page);
4257 page_cache_release(page);
4258 }
4259 len -= bytes;
4260 buf += bytes;
4261 addr += bytes;
4262 }
4263 up_read(&mm->mmap_sem);
4264
4265 return buf - old_buf;
4266}
4267
4268/**
4269 * access_remote_vm - access another process' address space
4270 * @mm: the mm_struct of the target address space
4271 * @addr: start address to access
4272 * @buf: source or destination buffer
4273 * @len: number of bytes to transfer
4274 * @write: whether the access is a write
4275 *
4276 * The caller must hold a reference on @mm.
4277 */
4278int access_remote_vm(struct mm_struct *mm, unsigned long addr,
4279 void *buf, int len, int write)
4280{
4281 return __access_remote_vm(NULL, mm, addr, buf, len, write);
4282}
4283
4284/*
4285 * Access another process' address space.
4286 * Source/target buffer must be kernel space,
4287 * Do not walk the page table directly, use get_user_pages
4288 */
4289int access_process_vm(struct task_struct *tsk, unsigned long addr,
4290 void *buf, int len, int write)
4291{
4292 struct mm_struct *mm;
4293 int ret;
4294
4295 mm = get_task_mm(tsk);
4296 if (!mm)
4297 return 0;
4298
4299 ret = __access_remote_vm(tsk, mm, addr, buf, len, write);
4300 mmput(mm);
4301
4302 return ret;
4303}
4304
4305/*
4306 * Print the name of a VMA.
4307 */
4308void print_vma_addr(char *prefix, unsigned long ip)
4309{
4310 struct mm_struct *mm = current->mm;
4311 struct vm_area_struct *vma;
4312
4313 /*
4314 * Do not print if we are in atomic
4315 * contexts (in exception stacks, etc.):
4316 */
4317 if (preempt_count())
4318 return;
4319
4320 down_read(&mm->mmap_sem);
4321 vma = find_vma(mm, ip);
4322 if (vma && vma->vm_file) {
4323 struct file *f = vma->vm_file;
4324 char *buf = (char *)__get_free_page(GFP_KERNEL);
4325 if (buf) {
4326 char *p;
4327
4328 p = d_path(&f->f_path, buf, PAGE_SIZE);
4329 if (IS_ERR(p))
4330 p = "?";
4331 printk("%s%s[%lx+%lx]", prefix, kbasename(p),
4332 vma->vm_start,
4333 vma->vm_end - vma->vm_start);
4334 free_page((unsigned long)buf);
4335 }
4336 }
4337 up_read(&mm->mmap_sem);
4338}
4339
4340#if defined(CONFIG_PROVE_LOCKING) || defined(CONFIG_DEBUG_ATOMIC_SLEEP)
4341void might_fault(void)
4342{
4343 /*
4344 * Some code (nfs/sunrpc) uses socket ops on kernel memory while
4345 * holding the mmap_sem, this is safe because kernel memory doesn't
4346 * get paged out, therefore we'll never actually fault, and the
4347 * below annotations will generate false positives.
4348 */
4349 if (segment_eq(get_fs(), KERNEL_DS))
4350 return;
4351
4352 /*
4353 * it would be nicer only to annotate paths which are not under
4354 * pagefault_disable, however that requires a larger audit and
4355 * providing helpers like get_user_atomic.
4356 */
4357 if (in_atomic())
4358 return;
4359
4360 __might_sleep(__FILE__, __LINE__, 0);
4361
4362 if (current->mm)
4363 might_lock_read(¤t->mm->mmap_sem);
4364}
4365EXPORT_SYMBOL(might_fault);
4366#endif
4367
4368#if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
4369static void clear_gigantic_page(struct page *page,
4370 unsigned long addr,
4371 unsigned int pages_per_huge_page)
4372{
4373 int i;
4374 struct page *p = page;
4375
4376 might_sleep();
4377 for (i = 0; i < pages_per_huge_page;
4378 i++, p = mem_map_next(p, page, i)) {
4379 cond_resched();
4380 clear_user_highpage(p, addr + i * PAGE_SIZE);
4381 }
4382}
4383void clear_huge_page(struct page *page,
4384 unsigned long addr, unsigned int pages_per_huge_page)
4385{
4386 int i;
4387
4388 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4389 clear_gigantic_page(page, addr, pages_per_huge_page);
4390 return;
4391 }
4392
4393 might_sleep();
4394 for (i = 0; i < pages_per_huge_page; i++) {
4395 cond_resched();
4396 clear_user_highpage(page + i, addr + i * PAGE_SIZE);
4397 }
4398}
4399
4400static void copy_user_gigantic_page(struct page *dst, struct page *src,
4401 unsigned long addr,
4402 struct vm_area_struct *vma,
4403 unsigned int pages_per_huge_page)
4404{
4405 int i;
4406 struct page *dst_base = dst;
4407 struct page *src_base = src;
4408
4409 for (i = 0; i < pages_per_huge_page; ) {
4410 cond_resched();
4411 copy_user_highpage(dst, src, addr + i*PAGE_SIZE, vma);
4412
4413 i++;
4414 dst = mem_map_next(dst, dst_base, i);
4415 src = mem_map_next(src, src_base, i);
4416 }
4417}
4418
4419void copy_user_huge_page(struct page *dst, struct page *src,
4420 unsigned long addr, struct vm_area_struct *vma,
4421 unsigned int pages_per_huge_page)
4422{
4423 int i;
4424
4425 if (unlikely(pages_per_huge_page > MAX_ORDER_NR_PAGES)) {
4426 copy_user_gigantic_page(dst, src, addr, vma,
4427 pages_per_huge_page);
4428 return;
4429 }
4430
4431 might_sleep();
4432 for (i = 0; i < pages_per_huge_page; i++) {
4433 cond_resched();
4434 copy_user_highpage(dst + i, src + i, addr + i*PAGE_SIZE, vma);
4435 }
4436}
4437#endif /* CONFIG_TRANSPARENT_HUGEPAGE || CONFIG_HUGETLBFS */
4438
4439#if USE_SPLIT_PTE_PTLOCKS && ALLOC_SPLIT_PTLOCKS
4440
4441static struct kmem_cache *page_ptl_cachep;
4442
4443void __init ptlock_cache_init(void)
4444{
4445 page_ptl_cachep = kmem_cache_create("page->ptl", sizeof(spinlock_t), 0,
4446 SLAB_PANIC, NULL);
4447}
4448
4449bool ptlock_alloc(struct page *page)
4450{
4451 spinlock_t *ptl;
4452
4453 ptl = kmem_cache_alloc(page_ptl_cachep, GFP_KERNEL);
4454 if (!ptl)
4455 return false;
4456 page->ptl = ptl;
4457 return true;
4458}
4459
4460void ptlock_free(struct page *page)
4461{
4462 kmem_cache_free(page_ptl_cachep, page->ptl);
4463}
4464#endif