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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/mm/madvise.c
4 *
5 * Copyright (C) 1999 Linus Torvalds
6 * Copyright (C) 2002 Christoph Hellwig
7 */
8
9#include <linux/mman.h>
10#include <linux/pagemap.h>
11#include <linux/syscalls.h>
12#include <linux/mempolicy.h>
13#include <linux/page-isolation.h>
14#include <linux/page_idle.h>
15#include <linux/userfaultfd_k.h>
16#include <linux/hugetlb.h>
17#include <linux/falloc.h>
18#include <linux/fadvise.h>
19#include <linux/sched.h>
20#include <linux/sched/mm.h>
21#include <linux/mm_inline.h>
22#include <linux/string.h>
23#include <linux/uio.h>
24#include <linux/ksm.h>
25#include <linux/fs.h>
26#include <linux/file.h>
27#include <linux/blkdev.h>
28#include <linux/backing-dev.h>
29#include <linux/pagewalk.h>
30#include <linux/swap.h>
31#include <linux/swapops.h>
32#include <linux/shmem_fs.h>
33#include <linux/mmu_notifier.h>
34
35#include <asm/tlb.h>
36
37#include "internal.h"
38#include "swap.h"
39
40struct madvise_walk_private {
41 struct mmu_gather *tlb;
42 bool pageout;
43};
44
45/*
46 * Any behaviour which results in changes to the vma->vm_flags needs to
47 * take mmap_lock for writing. Others, which simply traverse vmas, need
48 * to only take it for reading.
49 */
50static int madvise_need_mmap_write(int behavior)
51{
52 switch (behavior) {
53 case MADV_REMOVE:
54 case MADV_WILLNEED:
55 case MADV_DONTNEED:
56 case MADV_DONTNEED_LOCKED:
57 case MADV_COLD:
58 case MADV_PAGEOUT:
59 case MADV_FREE:
60 case MADV_POPULATE_READ:
61 case MADV_POPULATE_WRITE:
62 case MADV_COLLAPSE:
63 return 0;
64 default:
65 /* be safe, default to 1. list exceptions explicitly */
66 return 1;
67 }
68}
69
70#ifdef CONFIG_ANON_VMA_NAME
71struct anon_vma_name *anon_vma_name_alloc(const char *name)
72{
73 struct anon_vma_name *anon_name;
74 size_t count;
75
76 /* Add 1 for NUL terminator at the end of the anon_name->name */
77 count = strlen(name) + 1;
78 anon_name = kmalloc(struct_size(anon_name, name, count), GFP_KERNEL);
79 if (anon_name) {
80 kref_init(&anon_name->kref);
81 memcpy(anon_name->name, name, count);
82 }
83
84 return anon_name;
85}
86
87void anon_vma_name_free(struct kref *kref)
88{
89 struct anon_vma_name *anon_name =
90 container_of(kref, struct anon_vma_name, kref);
91 kfree(anon_name);
92}
93
94struct anon_vma_name *anon_vma_name(struct vm_area_struct *vma)
95{
96 mmap_assert_locked(vma->vm_mm);
97
98 return vma->anon_name;
99}
100
101/* mmap_lock should be write-locked */
102static int replace_anon_vma_name(struct vm_area_struct *vma,
103 struct anon_vma_name *anon_name)
104{
105 struct anon_vma_name *orig_name = anon_vma_name(vma);
106
107 if (!anon_name) {
108 vma->anon_name = NULL;
109 anon_vma_name_put(orig_name);
110 return 0;
111 }
112
113 if (anon_vma_name_eq(orig_name, anon_name))
114 return 0;
115
116 vma->anon_name = anon_vma_name_reuse(anon_name);
117 anon_vma_name_put(orig_name);
118
119 return 0;
120}
121#else /* CONFIG_ANON_VMA_NAME */
122static int replace_anon_vma_name(struct vm_area_struct *vma,
123 struct anon_vma_name *anon_name)
124{
125 if (anon_name)
126 return -EINVAL;
127
128 return 0;
129}
130#endif /* CONFIG_ANON_VMA_NAME */
131/*
132 * Update the vm_flags on region of a vma, splitting it or merging it as
133 * necessary. Must be called with mmap_lock held for writing;
134 * Caller should ensure anon_name stability by raising its refcount even when
135 * anon_name belongs to a valid vma because this function might free that vma.
136 */
137static int madvise_update_vma(struct vm_area_struct *vma,
138 struct vm_area_struct **prev, unsigned long start,
139 unsigned long end, unsigned long new_flags,
140 struct anon_vma_name *anon_name)
141{
142 struct mm_struct *mm = vma->vm_mm;
143 int error;
144 VMA_ITERATOR(vmi, mm, start);
145
146 if (new_flags == vma->vm_flags && anon_vma_name_eq(anon_vma_name(vma), anon_name)) {
147 *prev = vma;
148 return 0;
149 }
150
151 vma = vma_modify_flags_name(&vmi, *prev, vma, start, end, new_flags,
152 anon_name);
153 if (IS_ERR(vma))
154 return PTR_ERR(vma);
155
156 *prev = vma;
157
158 /* vm_flags is protected by the mmap_lock held in write mode. */
159 vma_start_write(vma);
160 vm_flags_reset(vma, new_flags);
161 if (!vma->vm_file || vma_is_anon_shmem(vma)) {
162 error = replace_anon_vma_name(vma, anon_name);
163 if (error)
164 return error;
165 }
166
167 return 0;
168}
169
170#ifdef CONFIG_SWAP
171static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
172 unsigned long end, struct mm_walk *walk)
173{
174 struct vm_area_struct *vma = walk->private;
175 struct swap_iocb *splug = NULL;
176 pte_t *ptep = NULL;
177 spinlock_t *ptl;
178 unsigned long addr;
179
180 for (addr = start; addr < end; addr += PAGE_SIZE) {
181 pte_t pte;
182 swp_entry_t entry;
183 struct folio *folio;
184
185 if (!ptep++) {
186 ptep = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
187 if (!ptep)
188 break;
189 }
190
191 pte = ptep_get(ptep);
192 if (!is_swap_pte(pte))
193 continue;
194 entry = pte_to_swp_entry(pte);
195 if (unlikely(non_swap_entry(entry)))
196 continue;
197
198 pte_unmap_unlock(ptep, ptl);
199 ptep = NULL;
200
201 folio = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
202 vma, addr, &splug);
203 if (folio)
204 folio_put(folio);
205 }
206
207 if (ptep)
208 pte_unmap_unlock(ptep, ptl);
209 swap_read_unplug(splug);
210 cond_resched();
211
212 return 0;
213}
214
215static const struct mm_walk_ops swapin_walk_ops = {
216 .pmd_entry = swapin_walk_pmd_entry,
217 .walk_lock = PGWALK_RDLOCK,
218};
219
220static void shmem_swapin_range(struct vm_area_struct *vma,
221 unsigned long start, unsigned long end,
222 struct address_space *mapping)
223{
224 XA_STATE(xas, &mapping->i_pages, linear_page_index(vma, start));
225 pgoff_t end_index = linear_page_index(vma, end) - 1;
226 struct folio *folio;
227 struct swap_iocb *splug = NULL;
228
229 rcu_read_lock();
230 xas_for_each(&xas, folio, end_index) {
231 unsigned long addr;
232 swp_entry_t entry;
233
234 if (!xa_is_value(folio))
235 continue;
236 entry = radix_to_swp_entry(folio);
237 /* There might be swapin error entries in shmem mapping. */
238 if (non_swap_entry(entry))
239 continue;
240
241 addr = vma->vm_start +
242 ((xas.xa_index - vma->vm_pgoff) << PAGE_SHIFT);
243 xas_pause(&xas);
244 rcu_read_unlock();
245
246 folio = read_swap_cache_async(entry, mapping_gfp_mask(mapping),
247 vma, addr, &splug);
248 if (folio)
249 folio_put(folio);
250
251 rcu_read_lock();
252 }
253 rcu_read_unlock();
254 swap_read_unplug(splug);
255}
256#endif /* CONFIG_SWAP */
257
258/*
259 * Schedule all required I/O operations. Do not wait for completion.
260 */
261static long madvise_willneed(struct vm_area_struct *vma,
262 struct vm_area_struct **prev,
263 unsigned long start, unsigned long end)
264{
265 struct mm_struct *mm = vma->vm_mm;
266 struct file *file = vma->vm_file;
267 loff_t offset;
268
269 *prev = vma;
270#ifdef CONFIG_SWAP
271 if (!file) {
272 walk_page_range(vma->vm_mm, start, end, &swapin_walk_ops, vma);
273 lru_add_drain(); /* Push any new pages onto the LRU now */
274 return 0;
275 }
276
277 if (shmem_mapping(file->f_mapping)) {
278 shmem_swapin_range(vma, start, end, file->f_mapping);
279 lru_add_drain(); /* Push any new pages onto the LRU now */
280 return 0;
281 }
282#else
283 if (!file)
284 return -EBADF;
285#endif
286
287 if (IS_DAX(file_inode(file))) {
288 /* no bad return value, but ignore advice */
289 return 0;
290 }
291
292 /*
293 * Filesystem's fadvise may need to take various locks. We need to
294 * explicitly grab a reference because the vma (and hence the
295 * vma's reference to the file) can go away as soon as we drop
296 * mmap_lock.
297 */
298 *prev = NULL; /* tell sys_madvise we drop mmap_lock */
299 get_file(file);
300 offset = (loff_t)(start - vma->vm_start)
301 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
302 mmap_read_unlock(mm);
303 vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED);
304 fput(file);
305 mmap_read_lock(mm);
306 return 0;
307}
308
309static inline bool can_do_file_pageout(struct vm_area_struct *vma)
310{
311 if (!vma->vm_file)
312 return false;
313 /*
314 * paging out pagecache only for non-anonymous mappings that correspond
315 * to the files the calling process could (if tried) open for writing;
316 * otherwise we'd be including shared non-exclusive mappings, which
317 * opens a side channel.
318 */
319 return inode_owner_or_capable(&nop_mnt_idmap,
320 file_inode(vma->vm_file)) ||
321 file_permission(vma->vm_file, MAY_WRITE) == 0;
322}
323
324static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
325 unsigned long addr, unsigned long end,
326 struct mm_walk *walk)
327{
328 struct madvise_walk_private *private = walk->private;
329 struct mmu_gather *tlb = private->tlb;
330 bool pageout = private->pageout;
331 struct mm_struct *mm = tlb->mm;
332 struct vm_area_struct *vma = walk->vma;
333 pte_t *start_pte, *pte, ptent;
334 spinlock_t *ptl;
335 struct folio *folio = NULL;
336 LIST_HEAD(folio_list);
337 bool pageout_anon_only_filter;
338 unsigned int batch_count = 0;
339
340 if (fatal_signal_pending(current))
341 return -EINTR;
342
343 pageout_anon_only_filter = pageout && !vma_is_anonymous(vma) &&
344 !can_do_file_pageout(vma);
345
346#ifdef CONFIG_TRANSPARENT_HUGEPAGE
347 if (pmd_trans_huge(*pmd)) {
348 pmd_t orig_pmd;
349 unsigned long next = pmd_addr_end(addr, end);
350
351 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
352 ptl = pmd_trans_huge_lock(pmd, vma);
353 if (!ptl)
354 return 0;
355
356 orig_pmd = *pmd;
357 if (is_huge_zero_pmd(orig_pmd))
358 goto huge_unlock;
359
360 if (unlikely(!pmd_present(orig_pmd))) {
361 VM_BUG_ON(thp_migration_supported() &&
362 !is_pmd_migration_entry(orig_pmd));
363 goto huge_unlock;
364 }
365
366 folio = pfn_folio(pmd_pfn(orig_pmd));
367
368 /* Do not interfere with other mappings of this folio */
369 if (folio_estimated_sharers(folio) != 1)
370 goto huge_unlock;
371
372 if (pageout_anon_only_filter && !folio_test_anon(folio))
373 goto huge_unlock;
374
375 if (next - addr != HPAGE_PMD_SIZE) {
376 int err;
377
378 folio_get(folio);
379 spin_unlock(ptl);
380 folio_lock(folio);
381 err = split_folio(folio);
382 folio_unlock(folio);
383 folio_put(folio);
384 if (!err)
385 goto regular_folio;
386 return 0;
387 }
388
389 if (pmd_young(orig_pmd)) {
390 pmdp_invalidate(vma, addr, pmd);
391 orig_pmd = pmd_mkold(orig_pmd);
392
393 set_pmd_at(mm, addr, pmd, orig_pmd);
394 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
395 }
396
397 folio_clear_referenced(folio);
398 folio_test_clear_young(folio);
399 if (folio_test_active(folio))
400 folio_set_workingset(folio);
401 if (pageout) {
402 if (folio_isolate_lru(folio)) {
403 if (folio_test_unevictable(folio))
404 folio_putback_lru(folio);
405 else
406 list_add(&folio->lru, &folio_list);
407 }
408 } else
409 folio_deactivate(folio);
410huge_unlock:
411 spin_unlock(ptl);
412 if (pageout)
413 reclaim_pages(&folio_list);
414 return 0;
415 }
416
417regular_folio:
418#endif
419 tlb_change_page_size(tlb, PAGE_SIZE);
420restart:
421 start_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
422 if (!start_pte)
423 return 0;
424 flush_tlb_batched_pending(mm);
425 arch_enter_lazy_mmu_mode();
426 for (; addr < end; pte++, addr += PAGE_SIZE) {
427 ptent = ptep_get(pte);
428
429 if (++batch_count == SWAP_CLUSTER_MAX) {
430 batch_count = 0;
431 if (need_resched()) {
432 arch_leave_lazy_mmu_mode();
433 pte_unmap_unlock(start_pte, ptl);
434 cond_resched();
435 goto restart;
436 }
437 }
438
439 if (pte_none(ptent))
440 continue;
441
442 if (!pte_present(ptent))
443 continue;
444
445 folio = vm_normal_folio(vma, addr, ptent);
446 if (!folio || folio_is_zone_device(folio))
447 continue;
448
449 /*
450 * Creating a THP page is expensive so split it only if we
451 * are sure it's worth. Split it if we are only owner.
452 */
453 if (folio_test_large(folio)) {
454 int err;
455
456 if (folio_estimated_sharers(folio) != 1)
457 break;
458 if (pageout_anon_only_filter && !folio_test_anon(folio))
459 break;
460 if (!folio_trylock(folio))
461 break;
462 folio_get(folio);
463 arch_leave_lazy_mmu_mode();
464 pte_unmap_unlock(start_pte, ptl);
465 start_pte = NULL;
466 err = split_folio(folio);
467 folio_unlock(folio);
468 folio_put(folio);
469 if (err)
470 break;
471 start_pte = pte =
472 pte_offset_map_lock(mm, pmd, addr, &ptl);
473 if (!start_pte)
474 break;
475 arch_enter_lazy_mmu_mode();
476 pte--;
477 addr -= PAGE_SIZE;
478 continue;
479 }
480
481 /*
482 * Do not interfere with other mappings of this folio and
483 * non-LRU folio.
484 */
485 if (!folio_test_lru(folio) || folio_mapcount(folio) != 1)
486 continue;
487
488 if (pageout_anon_only_filter && !folio_test_anon(folio))
489 continue;
490
491 VM_BUG_ON_FOLIO(folio_test_large(folio), folio);
492
493 if (pte_young(ptent)) {
494 ptent = ptep_get_and_clear_full(mm, addr, pte,
495 tlb->fullmm);
496 ptent = pte_mkold(ptent);
497 set_pte_at(mm, addr, pte, ptent);
498 tlb_remove_tlb_entry(tlb, pte, addr);
499 }
500
501 /*
502 * We are deactivating a folio for accelerating reclaiming.
503 * VM couldn't reclaim the folio unless we clear PG_young.
504 * As a side effect, it makes confuse idle-page tracking
505 * because they will miss recent referenced history.
506 */
507 folio_clear_referenced(folio);
508 folio_test_clear_young(folio);
509 if (folio_test_active(folio))
510 folio_set_workingset(folio);
511 if (pageout) {
512 if (folio_isolate_lru(folio)) {
513 if (folio_test_unevictable(folio))
514 folio_putback_lru(folio);
515 else
516 list_add(&folio->lru, &folio_list);
517 }
518 } else
519 folio_deactivate(folio);
520 }
521
522 if (start_pte) {
523 arch_leave_lazy_mmu_mode();
524 pte_unmap_unlock(start_pte, ptl);
525 }
526 if (pageout)
527 reclaim_pages(&folio_list);
528 cond_resched();
529
530 return 0;
531}
532
533static const struct mm_walk_ops cold_walk_ops = {
534 .pmd_entry = madvise_cold_or_pageout_pte_range,
535 .walk_lock = PGWALK_RDLOCK,
536};
537
538static void madvise_cold_page_range(struct mmu_gather *tlb,
539 struct vm_area_struct *vma,
540 unsigned long addr, unsigned long end)
541{
542 struct madvise_walk_private walk_private = {
543 .pageout = false,
544 .tlb = tlb,
545 };
546
547 tlb_start_vma(tlb, vma);
548 walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
549 tlb_end_vma(tlb, vma);
550}
551
552static inline bool can_madv_lru_vma(struct vm_area_struct *vma)
553{
554 return !(vma->vm_flags & (VM_LOCKED|VM_PFNMAP|VM_HUGETLB));
555}
556
557static long madvise_cold(struct vm_area_struct *vma,
558 struct vm_area_struct **prev,
559 unsigned long start_addr, unsigned long end_addr)
560{
561 struct mm_struct *mm = vma->vm_mm;
562 struct mmu_gather tlb;
563
564 *prev = vma;
565 if (!can_madv_lru_vma(vma))
566 return -EINVAL;
567
568 lru_add_drain();
569 tlb_gather_mmu(&tlb, mm);
570 madvise_cold_page_range(&tlb, vma, start_addr, end_addr);
571 tlb_finish_mmu(&tlb);
572
573 return 0;
574}
575
576static void madvise_pageout_page_range(struct mmu_gather *tlb,
577 struct vm_area_struct *vma,
578 unsigned long addr, unsigned long end)
579{
580 struct madvise_walk_private walk_private = {
581 .pageout = true,
582 .tlb = tlb,
583 };
584
585 tlb_start_vma(tlb, vma);
586 walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
587 tlb_end_vma(tlb, vma);
588}
589
590static long madvise_pageout(struct vm_area_struct *vma,
591 struct vm_area_struct **prev,
592 unsigned long start_addr, unsigned long end_addr)
593{
594 struct mm_struct *mm = vma->vm_mm;
595 struct mmu_gather tlb;
596
597 *prev = vma;
598 if (!can_madv_lru_vma(vma))
599 return -EINVAL;
600
601 /*
602 * If the VMA belongs to a private file mapping, there can be private
603 * dirty pages which can be paged out if even this process is neither
604 * owner nor write capable of the file. We allow private file mappings
605 * further to pageout dirty anon pages.
606 */
607 if (!vma_is_anonymous(vma) && (!can_do_file_pageout(vma) &&
608 (vma->vm_flags & VM_MAYSHARE)))
609 return 0;
610
611 lru_add_drain();
612 tlb_gather_mmu(&tlb, mm);
613 madvise_pageout_page_range(&tlb, vma, start_addr, end_addr);
614 tlb_finish_mmu(&tlb);
615
616 return 0;
617}
618
619static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
620 unsigned long end, struct mm_walk *walk)
621
622{
623 struct mmu_gather *tlb = walk->private;
624 struct mm_struct *mm = tlb->mm;
625 struct vm_area_struct *vma = walk->vma;
626 spinlock_t *ptl;
627 pte_t *start_pte, *pte, ptent;
628 struct folio *folio;
629 int nr_swap = 0;
630 unsigned long next;
631
632 next = pmd_addr_end(addr, end);
633 if (pmd_trans_huge(*pmd))
634 if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next))
635 return 0;
636
637 tlb_change_page_size(tlb, PAGE_SIZE);
638 start_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
639 if (!start_pte)
640 return 0;
641 flush_tlb_batched_pending(mm);
642 arch_enter_lazy_mmu_mode();
643 for (; addr != end; pte++, addr += PAGE_SIZE) {
644 ptent = ptep_get(pte);
645
646 if (pte_none(ptent))
647 continue;
648 /*
649 * If the pte has swp_entry, just clear page table to
650 * prevent swap-in which is more expensive rather than
651 * (page allocation + zeroing).
652 */
653 if (!pte_present(ptent)) {
654 swp_entry_t entry;
655
656 entry = pte_to_swp_entry(ptent);
657 if (!non_swap_entry(entry)) {
658 nr_swap--;
659 free_swap_and_cache(entry);
660 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
661 } else if (is_hwpoison_entry(entry) ||
662 is_poisoned_swp_entry(entry)) {
663 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
664 }
665 continue;
666 }
667
668 folio = vm_normal_folio(vma, addr, ptent);
669 if (!folio || folio_is_zone_device(folio))
670 continue;
671
672 /*
673 * If pmd isn't transhuge but the folio is large and
674 * is owned by only this process, split it and
675 * deactivate all pages.
676 */
677 if (folio_test_large(folio)) {
678 int err;
679
680 if (folio_estimated_sharers(folio) != 1)
681 break;
682 if (!folio_trylock(folio))
683 break;
684 folio_get(folio);
685 arch_leave_lazy_mmu_mode();
686 pte_unmap_unlock(start_pte, ptl);
687 start_pte = NULL;
688 err = split_folio(folio);
689 folio_unlock(folio);
690 folio_put(folio);
691 if (err)
692 break;
693 start_pte = pte =
694 pte_offset_map_lock(mm, pmd, addr, &ptl);
695 if (!start_pte)
696 break;
697 arch_enter_lazy_mmu_mode();
698 pte--;
699 addr -= PAGE_SIZE;
700 continue;
701 }
702
703 if (folio_test_swapcache(folio) || folio_test_dirty(folio)) {
704 if (!folio_trylock(folio))
705 continue;
706 /*
707 * If folio is shared with others, we mustn't clear
708 * the folio's dirty flag.
709 */
710 if (folio_mapcount(folio) != 1) {
711 folio_unlock(folio);
712 continue;
713 }
714
715 if (folio_test_swapcache(folio) &&
716 !folio_free_swap(folio)) {
717 folio_unlock(folio);
718 continue;
719 }
720
721 folio_clear_dirty(folio);
722 folio_unlock(folio);
723 }
724
725 if (pte_young(ptent) || pte_dirty(ptent)) {
726 /*
727 * Some of architecture(ex, PPC) don't update TLB
728 * with set_pte_at and tlb_remove_tlb_entry so for
729 * the portability, remap the pte with old|clean
730 * after pte clearing.
731 */
732 ptent = ptep_get_and_clear_full(mm, addr, pte,
733 tlb->fullmm);
734
735 ptent = pte_mkold(ptent);
736 ptent = pte_mkclean(ptent);
737 set_pte_at(mm, addr, pte, ptent);
738 tlb_remove_tlb_entry(tlb, pte, addr);
739 }
740 folio_mark_lazyfree(folio);
741 }
742
743 if (nr_swap)
744 add_mm_counter(mm, MM_SWAPENTS, nr_swap);
745 if (start_pte) {
746 arch_leave_lazy_mmu_mode();
747 pte_unmap_unlock(start_pte, ptl);
748 }
749 cond_resched();
750
751 return 0;
752}
753
754static const struct mm_walk_ops madvise_free_walk_ops = {
755 .pmd_entry = madvise_free_pte_range,
756 .walk_lock = PGWALK_RDLOCK,
757};
758
759static int madvise_free_single_vma(struct vm_area_struct *vma,
760 unsigned long start_addr, unsigned long end_addr)
761{
762 struct mm_struct *mm = vma->vm_mm;
763 struct mmu_notifier_range range;
764 struct mmu_gather tlb;
765
766 /* MADV_FREE works for only anon vma at the moment */
767 if (!vma_is_anonymous(vma))
768 return -EINVAL;
769
770 range.start = max(vma->vm_start, start_addr);
771 if (range.start >= vma->vm_end)
772 return -EINVAL;
773 range.end = min(vma->vm_end, end_addr);
774 if (range.end <= vma->vm_start)
775 return -EINVAL;
776 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm,
777 range.start, range.end);
778
779 lru_add_drain();
780 tlb_gather_mmu(&tlb, mm);
781 update_hiwater_rss(mm);
782
783 mmu_notifier_invalidate_range_start(&range);
784 tlb_start_vma(&tlb, vma);
785 walk_page_range(vma->vm_mm, range.start, range.end,
786 &madvise_free_walk_ops, &tlb);
787 tlb_end_vma(&tlb, vma);
788 mmu_notifier_invalidate_range_end(&range);
789 tlb_finish_mmu(&tlb);
790
791 return 0;
792}
793
794/*
795 * Application no longer needs these pages. If the pages are dirty,
796 * it's OK to just throw them away. The app will be more careful about
797 * data it wants to keep. Be sure to free swap resources too. The
798 * zap_page_range_single call sets things up for shrink_active_list to actually
799 * free these pages later if no one else has touched them in the meantime,
800 * although we could add these pages to a global reuse list for
801 * shrink_active_list to pick up before reclaiming other pages.
802 *
803 * NB: This interface discards data rather than pushes it out to swap,
804 * as some implementations do. This has performance implications for
805 * applications like large transactional databases which want to discard
806 * pages in anonymous maps after committing to backing store the data
807 * that was kept in them. There is no reason to write this data out to
808 * the swap area if the application is discarding it.
809 *
810 * An interface that causes the system to free clean pages and flush
811 * dirty pages is already available as msync(MS_INVALIDATE).
812 */
813static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
814 unsigned long start, unsigned long end)
815{
816 zap_page_range_single(vma, start, end - start, NULL);
817 return 0;
818}
819
820static bool madvise_dontneed_free_valid_vma(struct vm_area_struct *vma,
821 unsigned long start,
822 unsigned long *end,
823 int behavior)
824{
825 if (!is_vm_hugetlb_page(vma)) {
826 unsigned int forbidden = VM_PFNMAP;
827
828 if (behavior != MADV_DONTNEED_LOCKED)
829 forbidden |= VM_LOCKED;
830
831 return !(vma->vm_flags & forbidden);
832 }
833
834 if (behavior != MADV_DONTNEED && behavior != MADV_DONTNEED_LOCKED)
835 return false;
836 if (start & ~huge_page_mask(hstate_vma(vma)))
837 return false;
838
839 /*
840 * Madvise callers expect the length to be rounded up to PAGE_SIZE
841 * boundaries, and may be unaware that this VMA uses huge pages.
842 * Avoid unexpected data loss by rounding down the number of
843 * huge pages freed.
844 */
845 *end = ALIGN_DOWN(*end, huge_page_size(hstate_vma(vma)));
846
847 return true;
848}
849
850static long madvise_dontneed_free(struct vm_area_struct *vma,
851 struct vm_area_struct **prev,
852 unsigned long start, unsigned long end,
853 int behavior)
854{
855 struct mm_struct *mm = vma->vm_mm;
856
857 *prev = vma;
858 if (!madvise_dontneed_free_valid_vma(vma, start, &end, behavior))
859 return -EINVAL;
860
861 if (start == end)
862 return 0;
863
864 if (!userfaultfd_remove(vma, start, end)) {
865 *prev = NULL; /* mmap_lock has been dropped, prev is stale */
866
867 mmap_read_lock(mm);
868 vma = vma_lookup(mm, start);
869 if (!vma)
870 return -ENOMEM;
871 /*
872 * Potential end adjustment for hugetlb vma is OK as
873 * the check below keeps end within vma.
874 */
875 if (!madvise_dontneed_free_valid_vma(vma, start, &end,
876 behavior))
877 return -EINVAL;
878 if (end > vma->vm_end) {
879 /*
880 * Don't fail if end > vma->vm_end. If the old
881 * vma was split while the mmap_lock was
882 * released the effect of the concurrent
883 * operation may not cause madvise() to
884 * have an undefined result. There may be an
885 * adjacent next vma that we'll walk
886 * next. userfaultfd_remove() will generate an
887 * UFFD_EVENT_REMOVE repetition on the
888 * end-vma->vm_end range, but the manager can
889 * handle a repetition fine.
890 */
891 end = vma->vm_end;
892 }
893 VM_WARN_ON(start >= end);
894 }
895
896 if (behavior == MADV_DONTNEED || behavior == MADV_DONTNEED_LOCKED)
897 return madvise_dontneed_single_vma(vma, start, end);
898 else if (behavior == MADV_FREE)
899 return madvise_free_single_vma(vma, start, end);
900 else
901 return -EINVAL;
902}
903
904static long madvise_populate(struct vm_area_struct *vma,
905 struct vm_area_struct **prev,
906 unsigned long start, unsigned long end,
907 int behavior)
908{
909 const bool write = behavior == MADV_POPULATE_WRITE;
910 struct mm_struct *mm = vma->vm_mm;
911 unsigned long tmp_end;
912 int locked = 1;
913 long pages;
914
915 *prev = vma;
916
917 while (start < end) {
918 /*
919 * We might have temporarily dropped the lock. For example,
920 * our VMA might have been split.
921 */
922 if (!vma || start >= vma->vm_end) {
923 vma = vma_lookup(mm, start);
924 if (!vma)
925 return -ENOMEM;
926 }
927
928 tmp_end = min_t(unsigned long, end, vma->vm_end);
929 /* Populate (prefault) page tables readable/writable. */
930 pages = faultin_vma_page_range(vma, start, tmp_end, write,
931 &locked);
932 if (!locked) {
933 mmap_read_lock(mm);
934 locked = 1;
935 *prev = NULL;
936 vma = NULL;
937 }
938 if (pages < 0) {
939 switch (pages) {
940 case -EINTR:
941 return -EINTR;
942 case -EINVAL: /* Incompatible mappings / permissions. */
943 return -EINVAL;
944 case -EHWPOISON:
945 return -EHWPOISON;
946 case -EFAULT: /* VM_FAULT_SIGBUS or VM_FAULT_SIGSEGV */
947 return -EFAULT;
948 default:
949 pr_warn_once("%s: unhandled return value: %ld\n",
950 __func__, pages);
951 fallthrough;
952 case -ENOMEM:
953 return -ENOMEM;
954 }
955 }
956 start += pages * PAGE_SIZE;
957 }
958 return 0;
959}
960
961/*
962 * Application wants to free up the pages and associated backing store.
963 * This is effectively punching a hole into the middle of a file.
964 */
965static long madvise_remove(struct vm_area_struct *vma,
966 struct vm_area_struct **prev,
967 unsigned long start, unsigned long end)
968{
969 loff_t offset;
970 int error;
971 struct file *f;
972 struct mm_struct *mm = vma->vm_mm;
973
974 *prev = NULL; /* tell sys_madvise we drop mmap_lock */
975
976 if (vma->vm_flags & VM_LOCKED)
977 return -EINVAL;
978
979 f = vma->vm_file;
980
981 if (!f || !f->f_mapping || !f->f_mapping->host) {
982 return -EINVAL;
983 }
984
985 if (!vma_is_shared_maywrite(vma))
986 return -EACCES;
987
988 offset = (loff_t)(start - vma->vm_start)
989 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
990
991 /*
992 * Filesystem's fallocate may need to take i_rwsem. We need to
993 * explicitly grab a reference because the vma (and hence the
994 * vma's reference to the file) can go away as soon as we drop
995 * mmap_lock.
996 */
997 get_file(f);
998 if (userfaultfd_remove(vma, start, end)) {
999 /* mmap_lock was not released by userfaultfd_remove() */
1000 mmap_read_unlock(mm);
1001 }
1002 error = vfs_fallocate(f,
1003 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
1004 offset, end - start);
1005 fput(f);
1006 mmap_read_lock(mm);
1007 return error;
1008}
1009
1010/*
1011 * Apply an madvise behavior to a region of a vma. madvise_update_vma
1012 * will handle splitting a vm area into separate areas, each area with its own
1013 * behavior.
1014 */
1015static int madvise_vma_behavior(struct vm_area_struct *vma,
1016 struct vm_area_struct **prev,
1017 unsigned long start, unsigned long end,
1018 unsigned long behavior)
1019{
1020 int error;
1021 struct anon_vma_name *anon_name;
1022 unsigned long new_flags = vma->vm_flags;
1023
1024 switch (behavior) {
1025 case MADV_REMOVE:
1026 return madvise_remove(vma, prev, start, end);
1027 case MADV_WILLNEED:
1028 return madvise_willneed(vma, prev, start, end);
1029 case MADV_COLD:
1030 return madvise_cold(vma, prev, start, end);
1031 case MADV_PAGEOUT:
1032 return madvise_pageout(vma, prev, start, end);
1033 case MADV_FREE:
1034 case MADV_DONTNEED:
1035 case MADV_DONTNEED_LOCKED:
1036 return madvise_dontneed_free(vma, prev, start, end, behavior);
1037 case MADV_POPULATE_READ:
1038 case MADV_POPULATE_WRITE:
1039 return madvise_populate(vma, prev, start, end, behavior);
1040 case MADV_NORMAL:
1041 new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
1042 break;
1043 case MADV_SEQUENTIAL:
1044 new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
1045 break;
1046 case MADV_RANDOM:
1047 new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
1048 break;
1049 case MADV_DONTFORK:
1050 new_flags |= VM_DONTCOPY;
1051 break;
1052 case MADV_DOFORK:
1053 if (vma->vm_flags & VM_IO)
1054 return -EINVAL;
1055 new_flags &= ~VM_DONTCOPY;
1056 break;
1057 case MADV_WIPEONFORK:
1058 /* MADV_WIPEONFORK is only supported on anonymous memory. */
1059 if (vma->vm_file || vma->vm_flags & VM_SHARED)
1060 return -EINVAL;
1061 new_flags |= VM_WIPEONFORK;
1062 break;
1063 case MADV_KEEPONFORK:
1064 new_flags &= ~VM_WIPEONFORK;
1065 break;
1066 case MADV_DONTDUMP:
1067 new_flags |= VM_DONTDUMP;
1068 break;
1069 case MADV_DODUMP:
1070 if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL)
1071 return -EINVAL;
1072 new_flags &= ~VM_DONTDUMP;
1073 break;
1074 case MADV_MERGEABLE:
1075 case MADV_UNMERGEABLE:
1076 error = ksm_madvise(vma, start, end, behavior, &new_flags);
1077 if (error)
1078 goto out;
1079 break;
1080 case MADV_HUGEPAGE:
1081 case MADV_NOHUGEPAGE:
1082 error = hugepage_madvise(vma, &new_flags, behavior);
1083 if (error)
1084 goto out;
1085 break;
1086 case MADV_COLLAPSE:
1087 return madvise_collapse(vma, prev, start, end);
1088 }
1089
1090 anon_name = anon_vma_name(vma);
1091 anon_vma_name_get(anon_name);
1092 error = madvise_update_vma(vma, prev, start, end, new_flags,
1093 anon_name);
1094 anon_vma_name_put(anon_name);
1095
1096out:
1097 /*
1098 * madvise() returns EAGAIN if kernel resources, such as
1099 * slab, are temporarily unavailable.
1100 */
1101 if (error == -ENOMEM)
1102 error = -EAGAIN;
1103 return error;
1104}
1105
1106#ifdef CONFIG_MEMORY_FAILURE
1107/*
1108 * Error injection support for memory error handling.
1109 */
1110static int madvise_inject_error(int behavior,
1111 unsigned long start, unsigned long end)
1112{
1113 unsigned long size;
1114
1115 if (!capable(CAP_SYS_ADMIN))
1116 return -EPERM;
1117
1118
1119 for (; start < end; start += size) {
1120 unsigned long pfn;
1121 struct page *page;
1122 int ret;
1123
1124 ret = get_user_pages_fast(start, 1, 0, &page);
1125 if (ret != 1)
1126 return ret;
1127 pfn = page_to_pfn(page);
1128
1129 /*
1130 * When soft offlining hugepages, after migrating the page
1131 * we dissolve it, therefore in the second loop "page" will
1132 * no longer be a compound page.
1133 */
1134 size = page_size(compound_head(page));
1135
1136 if (behavior == MADV_SOFT_OFFLINE) {
1137 pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
1138 pfn, start);
1139 ret = soft_offline_page(pfn, MF_COUNT_INCREASED);
1140 } else {
1141 pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
1142 pfn, start);
1143 ret = memory_failure(pfn, MF_COUNT_INCREASED | MF_SW_SIMULATED);
1144 if (ret == -EOPNOTSUPP)
1145 ret = 0;
1146 }
1147
1148 if (ret)
1149 return ret;
1150 }
1151
1152 return 0;
1153}
1154#endif
1155
1156static bool
1157madvise_behavior_valid(int behavior)
1158{
1159 switch (behavior) {
1160 case MADV_DOFORK:
1161 case MADV_DONTFORK:
1162 case MADV_NORMAL:
1163 case MADV_SEQUENTIAL:
1164 case MADV_RANDOM:
1165 case MADV_REMOVE:
1166 case MADV_WILLNEED:
1167 case MADV_DONTNEED:
1168 case MADV_DONTNEED_LOCKED:
1169 case MADV_FREE:
1170 case MADV_COLD:
1171 case MADV_PAGEOUT:
1172 case MADV_POPULATE_READ:
1173 case MADV_POPULATE_WRITE:
1174#ifdef CONFIG_KSM
1175 case MADV_MERGEABLE:
1176 case MADV_UNMERGEABLE:
1177#endif
1178#ifdef CONFIG_TRANSPARENT_HUGEPAGE
1179 case MADV_HUGEPAGE:
1180 case MADV_NOHUGEPAGE:
1181 case MADV_COLLAPSE:
1182#endif
1183 case MADV_DONTDUMP:
1184 case MADV_DODUMP:
1185 case MADV_WIPEONFORK:
1186 case MADV_KEEPONFORK:
1187#ifdef CONFIG_MEMORY_FAILURE
1188 case MADV_SOFT_OFFLINE:
1189 case MADV_HWPOISON:
1190#endif
1191 return true;
1192
1193 default:
1194 return false;
1195 }
1196}
1197
1198static bool process_madvise_behavior_valid(int behavior)
1199{
1200 switch (behavior) {
1201 case MADV_COLD:
1202 case MADV_PAGEOUT:
1203 case MADV_WILLNEED:
1204 case MADV_COLLAPSE:
1205 return true;
1206 default:
1207 return false;
1208 }
1209}
1210
1211/*
1212 * Walk the vmas in range [start,end), and call the visit function on each one.
1213 * The visit function will get start and end parameters that cover the overlap
1214 * between the current vma and the original range. Any unmapped regions in the
1215 * original range will result in this function returning -ENOMEM while still
1216 * calling the visit function on all of the existing vmas in the range.
1217 * Must be called with the mmap_lock held for reading or writing.
1218 */
1219static
1220int madvise_walk_vmas(struct mm_struct *mm, unsigned long start,
1221 unsigned long end, unsigned long arg,
1222 int (*visit)(struct vm_area_struct *vma,
1223 struct vm_area_struct **prev, unsigned long start,
1224 unsigned long end, unsigned long arg))
1225{
1226 struct vm_area_struct *vma;
1227 struct vm_area_struct *prev;
1228 unsigned long tmp;
1229 int unmapped_error = 0;
1230
1231 /*
1232 * If the interval [start,end) covers some unmapped address
1233 * ranges, just ignore them, but return -ENOMEM at the end.
1234 * - different from the way of handling in mlock etc.
1235 */
1236 vma = find_vma_prev(mm, start, &prev);
1237 if (vma && start > vma->vm_start)
1238 prev = vma;
1239
1240 for (;;) {
1241 int error;
1242
1243 /* Still start < end. */
1244 if (!vma)
1245 return -ENOMEM;
1246
1247 /* Here start < (end|vma->vm_end). */
1248 if (start < vma->vm_start) {
1249 unmapped_error = -ENOMEM;
1250 start = vma->vm_start;
1251 if (start >= end)
1252 break;
1253 }
1254
1255 /* Here vma->vm_start <= start < (end|vma->vm_end) */
1256 tmp = vma->vm_end;
1257 if (end < tmp)
1258 tmp = end;
1259
1260 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
1261 error = visit(vma, &prev, start, tmp, arg);
1262 if (error)
1263 return error;
1264 start = tmp;
1265 if (prev && start < prev->vm_end)
1266 start = prev->vm_end;
1267 if (start >= end)
1268 break;
1269 if (prev)
1270 vma = find_vma(mm, prev->vm_end);
1271 else /* madvise_remove dropped mmap_lock */
1272 vma = find_vma(mm, start);
1273 }
1274
1275 return unmapped_error;
1276}
1277
1278#ifdef CONFIG_ANON_VMA_NAME
1279static int madvise_vma_anon_name(struct vm_area_struct *vma,
1280 struct vm_area_struct **prev,
1281 unsigned long start, unsigned long end,
1282 unsigned long anon_name)
1283{
1284 int error;
1285
1286 /* Only anonymous mappings can be named */
1287 if (vma->vm_file && !vma_is_anon_shmem(vma))
1288 return -EBADF;
1289
1290 error = madvise_update_vma(vma, prev, start, end, vma->vm_flags,
1291 (struct anon_vma_name *)anon_name);
1292
1293 /*
1294 * madvise() returns EAGAIN if kernel resources, such as
1295 * slab, are temporarily unavailable.
1296 */
1297 if (error == -ENOMEM)
1298 error = -EAGAIN;
1299 return error;
1300}
1301
1302int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
1303 unsigned long len_in, struct anon_vma_name *anon_name)
1304{
1305 unsigned long end;
1306 unsigned long len;
1307
1308 if (start & ~PAGE_MASK)
1309 return -EINVAL;
1310 len = (len_in + ~PAGE_MASK) & PAGE_MASK;
1311
1312 /* Check to see whether len was rounded up from small -ve to zero */
1313 if (len_in && !len)
1314 return -EINVAL;
1315
1316 end = start + len;
1317 if (end < start)
1318 return -EINVAL;
1319
1320 if (end == start)
1321 return 0;
1322
1323 return madvise_walk_vmas(mm, start, end, (unsigned long)anon_name,
1324 madvise_vma_anon_name);
1325}
1326#endif /* CONFIG_ANON_VMA_NAME */
1327/*
1328 * The madvise(2) system call.
1329 *
1330 * Applications can use madvise() to advise the kernel how it should
1331 * handle paging I/O in this VM area. The idea is to help the kernel
1332 * use appropriate read-ahead and caching techniques. The information
1333 * provided is advisory only, and can be safely disregarded by the
1334 * kernel without affecting the correct operation of the application.
1335 *
1336 * behavior values:
1337 * MADV_NORMAL - the default behavior is to read clusters. This
1338 * results in some read-ahead and read-behind.
1339 * MADV_RANDOM - the system should read the minimum amount of data
1340 * on any access, since it is unlikely that the appli-
1341 * cation will need more than what it asks for.
1342 * MADV_SEQUENTIAL - pages in the given range will probably be accessed
1343 * once, so they can be aggressively read ahead, and
1344 * can be freed soon after they are accessed.
1345 * MADV_WILLNEED - the application is notifying the system to read
1346 * some pages ahead.
1347 * MADV_DONTNEED - the application is finished with the given range,
1348 * so the kernel can free resources associated with it.
1349 * MADV_FREE - the application marks pages in the given range as lazy free,
1350 * where actual purges are postponed until memory pressure happens.
1351 * MADV_REMOVE - the application wants to free up the given range of
1352 * pages and associated backing store.
1353 * MADV_DONTFORK - omit this area from child's address space when forking:
1354 * typically, to avoid COWing pages pinned by get_user_pages().
1355 * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
1356 * MADV_WIPEONFORK - present the child process with zero-filled memory in this
1357 * range after a fork.
1358 * MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
1359 * MADV_HWPOISON - trigger memory error handler as if the given memory range
1360 * were corrupted by unrecoverable hardware memory failure.
1361 * MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
1362 * MADV_MERGEABLE - the application recommends that KSM try to merge pages in
1363 * this area with pages of identical content from other such areas.
1364 * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
1365 * MADV_HUGEPAGE - the application wants to back the given range by transparent
1366 * huge pages in the future. Existing pages might be coalesced and
1367 * new pages might be allocated as THP.
1368 * MADV_NOHUGEPAGE - mark the given range as not worth being backed by
1369 * transparent huge pages so the existing pages will not be
1370 * coalesced into THP and new pages will not be allocated as THP.
1371 * MADV_COLLAPSE - synchronously coalesce pages into new THP.
1372 * MADV_DONTDUMP - the application wants to prevent pages in the given range
1373 * from being included in its core dump.
1374 * MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
1375 * MADV_COLD - the application is not expected to use this memory soon,
1376 * deactivate pages in this range so that they can be reclaimed
1377 * easily if memory pressure happens.
1378 * MADV_PAGEOUT - the application is not expected to use this memory soon,
1379 * page out the pages in this range immediately.
1380 * MADV_POPULATE_READ - populate (prefault) page tables readable by
1381 * triggering read faults if required
1382 * MADV_POPULATE_WRITE - populate (prefault) page tables writable by
1383 * triggering write faults if required
1384 *
1385 * return values:
1386 * zero - success
1387 * -EINVAL - start + len < 0, start is not page-aligned,
1388 * "behavior" is not a valid value, or application
1389 * is attempting to release locked or shared pages,
1390 * or the specified address range includes file, Huge TLB,
1391 * MAP_SHARED or VMPFNMAP range.
1392 * -ENOMEM - addresses in the specified range are not currently
1393 * mapped, or are outside the AS of the process.
1394 * -EIO - an I/O error occurred while paging in data.
1395 * -EBADF - map exists, but area maps something that isn't a file.
1396 * -EAGAIN - a kernel resource was temporarily unavailable.
1397 */
1398int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior)
1399{
1400 unsigned long end;
1401 int error;
1402 int write;
1403 size_t len;
1404 struct blk_plug plug;
1405
1406 if (!madvise_behavior_valid(behavior))
1407 return -EINVAL;
1408
1409 if (!PAGE_ALIGNED(start))
1410 return -EINVAL;
1411 len = PAGE_ALIGN(len_in);
1412
1413 /* Check to see whether len was rounded up from small -ve to zero */
1414 if (len_in && !len)
1415 return -EINVAL;
1416
1417 end = start + len;
1418 if (end < start)
1419 return -EINVAL;
1420
1421 if (end == start)
1422 return 0;
1423
1424#ifdef CONFIG_MEMORY_FAILURE
1425 if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
1426 return madvise_inject_error(behavior, start, start + len_in);
1427#endif
1428
1429 write = madvise_need_mmap_write(behavior);
1430 if (write) {
1431 if (mmap_write_lock_killable(mm))
1432 return -EINTR;
1433 } else {
1434 mmap_read_lock(mm);
1435 }
1436
1437 start = untagged_addr_remote(mm, start);
1438 end = start + len;
1439
1440 blk_start_plug(&plug);
1441 error = madvise_walk_vmas(mm, start, end, behavior,
1442 madvise_vma_behavior);
1443 blk_finish_plug(&plug);
1444 if (write)
1445 mmap_write_unlock(mm);
1446 else
1447 mmap_read_unlock(mm);
1448
1449 return error;
1450}
1451
1452SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
1453{
1454 return do_madvise(current->mm, start, len_in, behavior);
1455}
1456
1457SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec,
1458 size_t, vlen, int, behavior, unsigned int, flags)
1459{
1460 ssize_t ret;
1461 struct iovec iovstack[UIO_FASTIOV];
1462 struct iovec *iov = iovstack;
1463 struct iov_iter iter;
1464 struct task_struct *task;
1465 struct mm_struct *mm;
1466 size_t total_len;
1467 unsigned int f_flags;
1468
1469 if (flags != 0) {
1470 ret = -EINVAL;
1471 goto out;
1472 }
1473
1474 ret = import_iovec(ITER_DEST, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
1475 if (ret < 0)
1476 goto out;
1477
1478 task = pidfd_get_task(pidfd, &f_flags);
1479 if (IS_ERR(task)) {
1480 ret = PTR_ERR(task);
1481 goto free_iov;
1482 }
1483
1484 if (!process_madvise_behavior_valid(behavior)) {
1485 ret = -EINVAL;
1486 goto release_task;
1487 }
1488
1489 /* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */
1490 mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
1491 if (IS_ERR_OR_NULL(mm)) {
1492 ret = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
1493 goto release_task;
1494 }
1495
1496 /*
1497 * Require CAP_SYS_NICE for influencing process performance. Note that
1498 * only non-destructive hints are currently supported.
1499 */
1500 if (!capable(CAP_SYS_NICE)) {
1501 ret = -EPERM;
1502 goto release_mm;
1503 }
1504
1505 total_len = iov_iter_count(&iter);
1506
1507 while (iov_iter_count(&iter)) {
1508 ret = do_madvise(mm, (unsigned long)iter_iov_addr(&iter),
1509 iter_iov_len(&iter), behavior);
1510 if (ret < 0)
1511 break;
1512 iov_iter_advance(&iter, iter_iov_len(&iter));
1513 }
1514
1515 ret = (total_len - iov_iter_count(&iter)) ? : ret;
1516
1517release_mm:
1518 mmput(mm);
1519release_task:
1520 put_task_struct(task);
1521free_iov:
1522 kfree(iov);
1523out:
1524 return ret;
1525}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/mm/madvise.c
4 *
5 * Copyright (C) 1999 Linus Torvalds
6 * Copyright (C) 2002 Christoph Hellwig
7 */
8
9#include <linux/mman.h>
10#include <linux/pagemap.h>
11#include <linux/syscalls.h>
12#include <linux/mempolicy.h>
13#include <linux/page-isolation.h>
14#include <linux/page_idle.h>
15#include <linux/userfaultfd_k.h>
16#include <linux/hugetlb.h>
17#include <linux/falloc.h>
18#include <linux/fadvise.h>
19#include <linux/sched.h>
20#include <linux/sched/mm.h>
21#include <linux/mm_inline.h>
22#include <linux/string.h>
23#include <linux/uio.h>
24#include <linux/ksm.h>
25#include <linux/fs.h>
26#include <linux/file.h>
27#include <linux/blkdev.h>
28#include <linux/backing-dev.h>
29#include <linux/pagewalk.h>
30#include <linux/swap.h>
31#include <linux/swapops.h>
32#include <linux/shmem_fs.h>
33#include <linux/mmu_notifier.h>
34
35#include <asm/tlb.h>
36
37#include "internal.h"
38#include "swap.h"
39
40struct madvise_walk_private {
41 struct mmu_gather *tlb;
42 bool pageout;
43};
44
45/*
46 * Any behaviour which results in changes to the vma->vm_flags needs to
47 * take mmap_lock for writing. Others, which simply traverse vmas, need
48 * to only take it for reading.
49 */
50static int madvise_need_mmap_write(int behavior)
51{
52 switch (behavior) {
53 case MADV_REMOVE:
54 case MADV_WILLNEED:
55 case MADV_DONTNEED:
56 case MADV_DONTNEED_LOCKED:
57 case MADV_COLD:
58 case MADV_PAGEOUT:
59 case MADV_FREE:
60 case MADV_POPULATE_READ:
61 case MADV_POPULATE_WRITE:
62 case MADV_COLLAPSE:
63 return 0;
64 default:
65 /* be safe, default to 1. list exceptions explicitly */
66 return 1;
67 }
68}
69
70#ifdef CONFIG_ANON_VMA_NAME
71struct anon_vma_name *anon_vma_name_alloc(const char *name)
72{
73 struct anon_vma_name *anon_name;
74 size_t count;
75
76 /* Add 1 for NUL terminator at the end of the anon_name->name */
77 count = strlen(name) + 1;
78 anon_name = kmalloc(struct_size(anon_name, name, count), GFP_KERNEL);
79 if (anon_name) {
80 kref_init(&anon_name->kref);
81 memcpy(anon_name->name, name, count);
82 }
83
84 return anon_name;
85}
86
87void anon_vma_name_free(struct kref *kref)
88{
89 struct anon_vma_name *anon_name =
90 container_of(kref, struct anon_vma_name, kref);
91 kfree(anon_name);
92}
93
94struct anon_vma_name *anon_vma_name(struct vm_area_struct *vma)
95{
96 mmap_assert_locked(vma->vm_mm);
97
98 return vma->anon_name;
99}
100
101/* mmap_lock should be write-locked */
102static int replace_anon_vma_name(struct vm_area_struct *vma,
103 struct anon_vma_name *anon_name)
104{
105 struct anon_vma_name *orig_name = anon_vma_name(vma);
106
107 if (!anon_name) {
108 vma->anon_name = NULL;
109 anon_vma_name_put(orig_name);
110 return 0;
111 }
112
113 if (anon_vma_name_eq(orig_name, anon_name))
114 return 0;
115
116 vma->anon_name = anon_vma_name_reuse(anon_name);
117 anon_vma_name_put(orig_name);
118
119 return 0;
120}
121#else /* CONFIG_ANON_VMA_NAME */
122static int replace_anon_vma_name(struct vm_area_struct *vma,
123 struct anon_vma_name *anon_name)
124{
125 if (anon_name)
126 return -EINVAL;
127
128 return 0;
129}
130#endif /* CONFIG_ANON_VMA_NAME */
131/*
132 * Update the vm_flags on region of a vma, splitting it or merging it as
133 * necessary. Must be called with mmap_lock held for writing;
134 * Caller should ensure anon_name stability by raising its refcount even when
135 * anon_name belongs to a valid vma because this function might free that vma.
136 */
137static int madvise_update_vma(struct vm_area_struct *vma,
138 struct vm_area_struct **prev, unsigned long start,
139 unsigned long end, unsigned long new_flags,
140 struct anon_vma_name *anon_name)
141{
142 struct mm_struct *mm = vma->vm_mm;
143 int error;
144 pgoff_t pgoff;
145
146 if (new_flags == vma->vm_flags && anon_vma_name_eq(anon_vma_name(vma), anon_name)) {
147 *prev = vma;
148 return 0;
149 }
150
151 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
152 *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
153 vma->vm_file, pgoff, vma_policy(vma),
154 vma->vm_userfaultfd_ctx, anon_name);
155 if (*prev) {
156 vma = *prev;
157 goto success;
158 }
159
160 *prev = vma;
161
162 if (start != vma->vm_start) {
163 if (unlikely(mm->map_count >= sysctl_max_map_count))
164 return -ENOMEM;
165 error = __split_vma(mm, vma, start, 1);
166 if (error)
167 return error;
168 }
169
170 if (end != vma->vm_end) {
171 if (unlikely(mm->map_count >= sysctl_max_map_count))
172 return -ENOMEM;
173 error = __split_vma(mm, vma, end, 0);
174 if (error)
175 return error;
176 }
177
178success:
179 /*
180 * vm_flags is protected by the mmap_lock held in write mode.
181 */
182 vma->vm_flags = new_flags;
183 if (!vma->vm_file || vma_is_anon_shmem(vma)) {
184 error = replace_anon_vma_name(vma, anon_name);
185 if (error)
186 return error;
187 }
188
189 return 0;
190}
191
192#ifdef CONFIG_SWAP
193static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
194 unsigned long end, struct mm_walk *walk)
195{
196 struct vm_area_struct *vma = walk->private;
197 unsigned long index;
198 struct swap_iocb *splug = NULL;
199
200 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
201 return 0;
202
203 for (index = start; index != end; index += PAGE_SIZE) {
204 pte_t pte;
205 swp_entry_t entry;
206 struct page *page;
207 spinlock_t *ptl;
208 pte_t *ptep;
209
210 ptep = pte_offset_map_lock(vma->vm_mm, pmd, index, &ptl);
211 pte = *ptep;
212 pte_unmap_unlock(ptep, ptl);
213
214 if (!is_swap_pte(pte))
215 continue;
216 entry = pte_to_swp_entry(pte);
217 if (unlikely(non_swap_entry(entry)))
218 continue;
219
220 page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
221 vma, index, false, &splug);
222 if (page)
223 put_page(page);
224 }
225 swap_read_unplug(splug);
226 cond_resched();
227
228 return 0;
229}
230
231static const struct mm_walk_ops swapin_walk_ops = {
232 .pmd_entry = swapin_walk_pmd_entry,
233};
234
235static void force_shm_swapin_readahead(struct vm_area_struct *vma,
236 unsigned long start, unsigned long end,
237 struct address_space *mapping)
238{
239 XA_STATE(xas, &mapping->i_pages, linear_page_index(vma, start));
240 pgoff_t end_index = linear_page_index(vma, end + PAGE_SIZE - 1);
241 struct page *page;
242 struct swap_iocb *splug = NULL;
243
244 rcu_read_lock();
245 xas_for_each(&xas, page, end_index) {
246 swp_entry_t swap;
247
248 if (!xa_is_value(page))
249 continue;
250 swap = radix_to_swp_entry(page);
251 /* There might be swapin error entries in shmem mapping. */
252 if (non_swap_entry(swap))
253 continue;
254 xas_pause(&xas);
255 rcu_read_unlock();
256
257 page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE,
258 NULL, 0, false, &splug);
259 if (page)
260 put_page(page);
261
262 rcu_read_lock();
263 }
264 rcu_read_unlock();
265 swap_read_unplug(splug);
266
267 lru_add_drain(); /* Push any new pages onto the LRU now */
268}
269#endif /* CONFIG_SWAP */
270
271/*
272 * Schedule all required I/O operations. Do not wait for completion.
273 */
274static long madvise_willneed(struct vm_area_struct *vma,
275 struct vm_area_struct **prev,
276 unsigned long start, unsigned long end)
277{
278 struct mm_struct *mm = vma->vm_mm;
279 struct file *file = vma->vm_file;
280 loff_t offset;
281
282 *prev = vma;
283#ifdef CONFIG_SWAP
284 if (!file) {
285 walk_page_range(vma->vm_mm, start, end, &swapin_walk_ops, vma);
286 lru_add_drain(); /* Push any new pages onto the LRU now */
287 return 0;
288 }
289
290 if (shmem_mapping(file->f_mapping)) {
291 force_shm_swapin_readahead(vma, start, end,
292 file->f_mapping);
293 return 0;
294 }
295#else
296 if (!file)
297 return -EBADF;
298#endif
299
300 if (IS_DAX(file_inode(file))) {
301 /* no bad return value, but ignore advice */
302 return 0;
303 }
304
305 /*
306 * Filesystem's fadvise may need to take various locks. We need to
307 * explicitly grab a reference because the vma (and hence the
308 * vma's reference to the file) can go away as soon as we drop
309 * mmap_lock.
310 */
311 *prev = NULL; /* tell sys_madvise we drop mmap_lock */
312 get_file(file);
313 offset = (loff_t)(start - vma->vm_start)
314 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
315 mmap_read_unlock(mm);
316 vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED);
317 fput(file);
318 mmap_read_lock(mm);
319 return 0;
320}
321
322static inline bool can_do_file_pageout(struct vm_area_struct *vma)
323{
324 if (!vma->vm_file)
325 return false;
326 /*
327 * paging out pagecache only for non-anonymous mappings that correspond
328 * to the files the calling process could (if tried) open for writing;
329 * otherwise we'd be including shared non-exclusive mappings, which
330 * opens a side channel.
331 */
332 return inode_owner_or_capable(&init_user_ns,
333 file_inode(vma->vm_file)) ||
334 file_permission(vma->vm_file, MAY_WRITE) == 0;
335}
336
337static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
338 unsigned long addr, unsigned long end,
339 struct mm_walk *walk)
340{
341 struct madvise_walk_private *private = walk->private;
342 struct mmu_gather *tlb = private->tlb;
343 bool pageout = private->pageout;
344 struct mm_struct *mm = tlb->mm;
345 struct vm_area_struct *vma = walk->vma;
346 pte_t *orig_pte, *pte, ptent;
347 spinlock_t *ptl;
348 struct page *page = NULL;
349 LIST_HEAD(page_list);
350 bool pageout_anon_only_filter;
351
352 if (fatal_signal_pending(current))
353 return -EINTR;
354
355 pageout_anon_only_filter = pageout && !vma_is_anonymous(vma) &&
356 !can_do_file_pageout(vma);
357
358#ifdef CONFIG_TRANSPARENT_HUGEPAGE
359 if (pmd_trans_huge(*pmd)) {
360 pmd_t orig_pmd;
361 unsigned long next = pmd_addr_end(addr, end);
362
363 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
364 ptl = pmd_trans_huge_lock(pmd, vma);
365 if (!ptl)
366 return 0;
367
368 orig_pmd = *pmd;
369 if (is_huge_zero_pmd(orig_pmd))
370 goto huge_unlock;
371
372 if (unlikely(!pmd_present(orig_pmd))) {
373 VM_BUG_ON(thp_migration_supported() &&
374 !is_pmd_migration_entry(orig_pmd));
375 goto huge_unlock;
376 }
377
378 page = pmd_page(orig_pmd);
379
380 /* Do not interfere with other mappings of this page */
381 if (page_mapcount(page) != 1)
382 goto huge_unlock;
383
384 if (pageout_anon_only_filter && !PageAnon(page))
385 goto huge_unlock;
386
387 if (next - addr != HPAGE_PMD_SIZE) {
388 int err;
389
390 get_page(page);
391 spin_unlock(ptl);
392 lock_page(page);
393 err = split_huge_page(page);
394 unlock_page(page);
395 put_page(page);
396 if (!err)
397 goto regular_page;
398 return 0;
399 }
400
401 if (pmd_young(orig_pmd)) {
402 pmdp_invalidate(vma, addr, pmd);
403 orig_pmd = pmd_mkold(orig_pmd);
404
405 set_pmd_at(mm, addr, pmd, orig_pmd);
406 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
407 }
408
409 ClearPageReferenced(page);
410 test_and_clear_page_young(page);
411 if (pageout) {
412 if (!isolate_lru_page(page)) {
413 if (PageUnevictable(page))
414 putback_lru_page(page);
415 else
416 list_add(&page->lru, &page_list);
417 }
418 } else
419 deactivate_page(page);
420huge_unlock:
421 spin_unlock(ptl);
422 if (pageout)
423 reclaim_pages(&page_list);
424 return 0;
425 }
426
427regular_page:
428 if (pmd_trans_unstable(pmd))
429 return 0;
430#endif
431 tlb_change_page_size(tlb, PAGE_SIZE);
432 orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
433 flush_tlb_batched_pending(mm);
434 arch_enter_lazy_mmu_mode();
435 for (; addr < end; pte++, addr += PAGE_SIZE) {
436 ptent = *pte;
437
438 if (pte_none(ptent))
439 continue;
440
441 if (!pte_present(ptent))
442 continue;
443
444 page = vm_normal_page(vma, addr, ptent);
445 if (!page || is_zone_device_page(page))
446 continue;
447
448 /*
449 * Creating a THP page is expensive so split it only if we
450 * are sure it's worth. Split it if we are only owner.
451 */
452 if (PageTransCompound(page)) {
453 if (page_mapcount(page) != 1)
454 break;
455 if (pageout_anon_only_filter && !PageAnon(page))
456 break;
457 get_page(page);
458 if (!trylock_page(page)) {
459 put_page(page);
460 break;
461 }
462 pte_unmap_unlock(orig_pte, ptl);
463 if (split_huge_page(page)) {
464 unlock_page(page);
465 put_page(page);
466 orig_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
467 break;
468 }
469 unlock_page(page);
470 put_page(page);
471 orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
472 pte--;
473 addr -= PAGE_SIZE;
474 continue;
475 }
476
477 /*
478 * Do not interfere with other mappings of this page and
479 * non-LRU page.
480 */
481 if (!PageLRU(page) || page_mapcount(page) != 1)
482 continue;
483
484 if (pageout_anon_only_filter && !PageAnon(page))
485 continue;
486
487 VM_BUG_ON_PAGE(PageTransCompound(page), page);
488
489 if (pte_young(ptent)) {
490 ptent = ptep_get_and_clear_full(mm, addr, pte,
491 tlb->fullmm);
492 ptent = pte_mkold(ptent);
493 set_pte_at(mm, addr, pte, ptent);
494 tlb_remove_tlb_entry(tlb, pte, addr);
495 }
496
497 /*
498 * We are deactivating a page for accelerating reclaiming.
499 * VM couldn't reclaim the page unless we clear PG_young.
500 * As a side effect, it makes confuse idle-page tracking
501 * because they will miss recent referenced history.
502 */
503 ClearPageReferenced(page);
504 test_and_clear_page_young(page);
505 if (pageout) {
506 if (!isolate_lru_page(page)) {
507 if (PageUnevictable(page))
508 putback_lru_page(page);
509 else
510 list_add(&page->lru, &page_list);
511 }
512 } else
513 deactivate_page(page);
514 }
515
516 arch_leave_lazy_mmu_mode();
517 pte_unmap_unlock(orig_pte, ptl);
518 if (pageout)
519 reclaim_pages(&page_list);
520 cond_resched();
521
522 return 0;
523}
524
525static const struct mm_walk_ops cold_walk_ops = {
526 .pmd_entry = madvise_cold_or_pageout_pte_range,
527};
528
529static void madvise_cold_page_range(struct mmu_gather *tlb,
530 struct vm_area_struct *vma,
531 unsigned long addr, unsigned long end)
532{
533 struct madvise_walk_private walk_private = {
534 .pageout = false,
535 .tlb = tlb,
536 };
537
538 tlb_start_vma(tlb, vma);
539 walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
540 tlb_end_vma(tlb, vma);
541}
542
543static inline bool can_madv_lru_vma(struct vm_area_struct *vma)
544{
545 return !(vma->vm_flags & (VM_LOCKED|VM_PFNMAP|VM_HUGETLB));
546}
547
548static long madvise_cold(struct vm_area_struct *vma,
549 struct vm_area_struct **prev,
550 unsigned long start_addr, unsigned long end_addr)
551{
552 struct mm_struct *mm = vma->vm_mm;
553 struct mmu_gather tlb;
554
555 *prev = vma;
556 if (!can_madv_lru_vma(vma))
557 return -EINVAL;
558
559 lru_add_drain();
560 tlb_gather_mmu(&tlb, mm);
561 madvise_cold_page_range(&tlb, vma, start_addr, end_addr);
562 tlb_finish_mmu(&tlb);
563
564 return 0;
565}
566
567static void madvise_pageout_page_range(struct mmu_gather *tlb,
568 struct vm_area_struct *vma,
569 unsigned long addr, unsigned long end)
570{
571 struct madvise_walk_private walk_private = {
572 .pageout = true,
573 .tlb = tlb,
574 };
575
576 tlb_start_vma(tlb, vma);
577 walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
578 tlb_end_vma(tlb, vma);
579}
580
581static long madvise_pageout(struct vm_area_struct *vma,
582 struct vm_area_struct **prev,
583 unsigned long start_addr, unsigned long end_addr)
584{
585 struct mm_struct *mm = vma->vm_mm;
586 struct mmu_gather tlb;
587
588 *prev = vma;
589 if (!can_madv_lru_vma(vma))
590 return -EINVAL;
591
592 /*
593 * If the VMA belongs to a private file mapping, there can be private
594 * dirty pages which can be paged out if even this process is neither
595 * owner nor write capable of the file. We allow private file mappings
596 * further to pageout dirty anon pages.
597 */
598 if (!vma_is_anonymous(vma) && (!can_do_file_pageout(vma) &&
599 (vma->vm_flags & VM_MAYSHARE)))
600 return 0;
601
602 lru_add_drain();
603 tlb_gather_mmu(&tlb, mm);
604 madvise_pageout_page_range(&tlb, vma, start_addr, end_addr);
605 tlb_finish_mmu(&tlb);
606
607 return 0;
608}
609
610static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
611 unsigned long end, struct mm_walk *walk)
612
613{
614 struct mmu_gather *tlb = walk->private;
615 struct mm_struct *mm = tlb->mm;
616 struct vm_area_struct *vma = walk->vma;
617 spinlock_t *ptl;
618 pte_t *orig_pte, *pte, ptent;
619 struct folio *folio;
620 struct page *page;
621 int nr_swap = 0;
622 unsigned long next;
623
624 next = pmd_addr_end(addr, end);
625 if (pmd_trans_huge(*pmd))
626 if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next))
627 goto next;
628
629 if (pmd_trans_unstable(pmd))
630 return 0;
631
632 tlb_change_page_size(tlb, PAGE_SIZE);
633 orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
634 flush_tlb_batched_pending(mm);
635 arch_enter_lazy_mmu_mode();
636 for (; addr != end; pte++, addr += PAGE_SIZE) {
637 ptent = *pte;
638
639 if (pte_none(ptent))
640 continue;
641 /*
642 * If the pte has swp_entry, just clear page table to
643 * prevent swap-in which is more expensive rather than
644 * (page allocation + zeroing).
645 */
646 if (!pte_present(ptent)) {
647 swp_entry_t entry;
648
649 entry = pte_to_swp_entry(ptent);
650 if (!non_swap_entry(entry)) {
651 nr_swap--;
652 free_swap_and_cache(entry);
653 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
654 } else if (is_hwpoison_entry(entry) ||
655 is_swapin_error_entry(entry)) {
656 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
657 }
658 continue;
659 }
660
661 page = vm_normal_page(vma, addr, ptent);
662 if (!page || is_zone_device_page(page))
663 continue;
664 folio = page_folio(page);
665
666 /*
667 * If pmd isn't transhuge but the folio is large and
668 * is owned by only this process, split it and
669 * deactivate all pages.
670 */
671 if (folio_test_large(folio)) {
672 if (folio_mapcount(folio) != 1)
673 goto out;
674 folio_get(folio);
675 if (!folio_trylock(folio)) {
676 folio_put(folio);
677 goto out;
678 }
679 pte_unmap_unlock(orig_pte, ptl);
680 if (split_folio(folio)) {
681 folio_unlock(folio);
682 folio_put(folio);
683 orig_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
684 goto out;
685 }
686 folio_unlock(folio);
687 folio_put(folio);
688 orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
689 pte--;
690 addr -= PAGE_SIZE;
691 continue;
692 }
693
694 if (folio_test_swapcache(folio) || folio_test_dirty(folio)) {
695 if (!folio_trylock(folio))
696 continue;
697 /*
698 * If folio is shared with others, we mustn't clear
699 * the folio's dirty flag.
700 */
701 if (folio_mapcount(folio) != 1) {
702 folio_unlock(folio);
703 continue;
704 }
705
706 if (folio_test_swapcache(folio) &&
707 !folio_free_swap(folio)) {
708 folio_unlock(folio);
709 continue;
710 }
711
712 folio_clear_dirty(folio);
713 folio_unlock(folio);
714 }
715
716 if (pte_young(ptent) || pte_dirty(ptent)) {
717 /*
718 * Some of architecture(ex, PPC) don't update TLB
719 * with set_pte_at and tlb_remove_tlb_entry so for
720 * the portability, remap the pte with old|clean
721 * after pte clearing.
722 */
723 ptent = ptep_get_and_clear_full(mm, addr, pte,
724 tlb->fullmm);
725
726 ptent = pte_mkold(ptent);
727 ptent = pte_mkclean(ptent);
728 set_pte_at(mm, addr, pte, ptent);
729 tlb_remove_tlb_entry(tlb, pte, addr);
730 }
731 mark_page_lazyfree(&folio->page);
732 }
733out:
734 if (nr_swap) {
735 if (current->mm == mm)
736 sync_mm_rss(mm);
737
738 add_mm_counter(mm, MM_SWAPENTS, nr_swap);
739 }
740 arch_leave_lazy_mmu_mode();
741 pte_unmap_unlock(orig_pte, ptl);
742 cond_resched();
743next:
744 return 0;
745}
746
747static const struct mm_walk_ops madvise_free_walk_ops = {
748 .pmd_entry = madvise_free_pte_range,
749};
750
751static int madvise_free_single_vma(struct vm_area_struct *vma,
752 unsigned long start_addr, unsigned long end_addr)
753{
754 struct mm_struct *mm = vma->vm_mm;
755 struct mmu_notifier_range range;
756 struct mmu_gather tlb;
757
758 /* MADV_FREE works for only anon vma at the moment */
759 if (!vma_is_anonymous(vma))
760 return -EINVAL;
761
762 range.start = max(vma->vm_start, start_addr);
763 if (range.start >= vma->vm_end)
764 return -EINVAL;
765 range.end = min(vma->vm_end, end_addr);
766 if (range.end <= vma->vm_start)
767 return -EINVAL;
768 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm,
769 range.start, range.end);
770
771 lru_add_drain();
772 tlb_gather_mmu(&tlb, mm);
773 update_hiwater_rss(mm);
774
775 mmu_notifier_invalidate_range_start(&range);
776 tlb_start_vma(&tlb, vma);
777 walk_page_range(vma->vm_mm, range.start, range.end,
778 &madvise_free_walk_ops, &tlb);
779 tlb_end_vma(&tlb, vma);
780 mmu_notifier_invalidate_range_end(&range);
781 tlb_finish_mmu(&tlb);
782
783 return 0;
784}
785
786/*
787 * Application no longer needs these pages. If the pages are dirty,
788 * it's OK to just throw them away. The app will be more careful about
789 * data it wants to keep. Be sure to free swap resources too. The
790 * zap_page_range_single call sets things up for shrink_active_list to actually
791 * free these pages later if no one else has touched them in the meantime,
792 * although we could add these pages to a global reuse list for
793 * shrink_active_list to pick up before reclaiming other pages.
794 *
795 * NB: This interface discards data rather than pushes it out to swap,
796 * as some implementations do. This has performance implications for
797 * applications like large transactional databases which want to discard
798 * pages in anonymous maps after committing to backing store the data
799 * that was kept in them. There is no reason to write this data out to
800 * the swap area if the application is discarding it.
801 *
802 * An interface that causes the system to free clean pages and flush
803 * dirty pages is already available as msync(MS_INVALIDATE).
804 */
805static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
806 unsigned long start, unsigned long end)
807{
808 zap_page_range_single(vma, start, end - start, NULL);
809 return 0;
810}
811
812static bool madvise_dontneed_free_valid_vma(struct vm_area_struct *vma,
813 unsigned long start,
814 unsigned long *end,
815 int behavior)
816{
817 if (!is_vm_hugetlb_page(vma)) {
818 unsigned int forbidden = VM_PFNMAP;
819
820 if (behavior != MADV_DONTNEED_LOCKED)
821 forbidden |= VM_LOCKED;
822
823 return !(vma->vm_flags & forbidden);
824 }
825
826 if (behavior != MADV_DONTNEED && behavior != MADV_DONTNEED_LOCKED)
827 return false;
828 if (start & ~huge_page_mask(hstate_vma(vma)))
829 return false;
830
831 /*
832 * Madvise callers expect the length to be rounded up to PAGE_SIZE
833 * boundaries, and may be unaware that this VMA uses huge pages.
834 * Avoid unexpected data loss by rounding down the number of
835 * huge pages freed.
836 */
837 *end = ALIGN_DOWN(*end, huge_page_size(hstate_vma(vma)));
838
839 return true;
840}
841
842static long madvise_dontneed_free(struct vm_area_struct *vma,
843 struct vm_area_struct **prev,
844 unsigned long start, unsigned long end,
845 int behavior)
846{
847 struct mm_struct *mm = vma->vm_mm;
848
849 *prev = vma;
850 if (!madvise_dontneed_free_valid_vma(vma, start, &end, behavior))
851 return -EINVAL;
852
853 if (start == end)
854 return 0;
855
856 if (!userfaultfd_remove(vma, start, end)) {
857 *prev = NULL; /* mmap_lock has been dropped, prev is stale */
858
859 mmap_read_lock(mm);
860 vma = find_vma(mm, start);
861 if (!vma)
862 return -ENOMEM;
863 if (start < vma->vm_start) {
864 /*
865 * This "vma" under revalidation is the one
866 * with the lowest vma->vm_start where start
867 * is also < vma->vm_end. If start <
868 * vma->vm_start it means an hole materialized
869 * in the user address space within the
870 * virtual range passed to MADV_DONTNEED
871 * or MADV_FREE.
872 */
873 return -ENOMEM;
874 }
875 /*
876 * Potential end adjustment for hugetlb vma is OK as
877 * the check below keeps end within vma.
878 */
879 if (!madvise_dontneed_free_valid_vma(vma, start, &end,
880 behavior))
881 return -EINVAL;
882 if (end > vma->vm_end) {
883 /*
884 * Don't fail if end > vma->vm_end. If the old
885 * vma was split while the mmap_lock was
886 * released the effect of the concurrent
887 * operation may not cause madvise() to
888 * have an undefined result. There may be an
889 * adjacent next vma that we'll walk
890 * next. userfaultfd_remove() will generate an
891 * UFFD_EVENT_REMOVE repetition on the
892 * end-vma->vm_end range, but the manager can
893 * handle a repetition fine.
894 */
895 end = vma->vm_end;
896 }
897 VM_WARN_ON(start >= end);
898 }
899
900 if (behavior == MADV_DONTNEED || behavior == MADV_DONTNEED_LOCKED)
901 return madvise_dontneed_single_vma(vma, start, end);
902 else if (behavior == MADV_FREE)
903 return madvise_free_single_vma(vma, start, end);
904 else
905 return -EINVAL;
906}
907
908static long madvise_populate(struct vm_area_struct *vma,
909 struct vm_area_struct **prev,
910 unsigned long start, unsigned long end,
911 int behavior)
912{
913 const bool write = behavior == MADV_POPULATE_WRITE;
914 struct mm_struct *mm = vma->vm_mm;
915 unsigned long tmp_end;
916 int locked = 1;
917 long pages;
918
919 *prev = vma;
920
921 while (start < end) {
922 /*
923 * We might have temporarily dropped the lock. For example,
924 * our VMA might have been split.
925 */
926 if (!vma || start >= vma->vm_end) {
927 vma = vma_lookup(mm, start);
928 if (!vma)
929 return -ENOMEM;
930 }
931
932 tmp_end = min_t(unsigned long, end, vma->vm_end);
933 /* Populate (prefault) page tables readable/writable. */
934 pages = faultin_vma_page_range(vma, start, tmp_end, write,
935 &locked);
936 if (!locked) {
937 mmap_read_lock(mm);
938 locked = 1;
939 *prev = NULL;
940 vma = NULL;
941 }
942 if (pages < 0) {
943 switch (pages) {
944 case -EINTR:
945 return -EINTR;
946 case -EINVAL: /* Incompatible mappings / permissions. */
947 return -EINVAL;
948 case -EHWPOISON:
949 return -EHWPOISON;
950 case -EFAULT: /* VM_FAULT_SIGBUS or VM_FAULT_SIGSEGV */
951 return -EFAULT;
952 default:
953 pr_warn_once("%s: unhandled return value: %ld\n",
954 __func__, pages);
955 fallthrough;
956 case -ENOMEM:
957 return -ENOMEM;
958 }
959 }
960 start += pages * PAGE_SIZE;
961 }
962 return 0;
963}
964
965/*
966 * Application wants to free up the pages and associated backing store.
967 * This is effectively punching a hole into the middle of a file.
968 */
969static long madvise_remove(struct vm_area_struct *vma,
970 struct vm_area_struct **prev,
971 unsigned long start, unsigned long end)
972{
973 loff_t offset;
974 int error;
975 struct file *f;
976 struct mm_struct *mm = vma->vm_mm;
977
978 *prev = NULL; /* tell sys_madvise we drop mmap_lock */
979
980 if (vma->vm_flags & VM_LOCKED)
981 return -EINVAL;
982
983 f = vma->vm_file;
984
985 if (!f || !f->f_mapping || !f->f_mapping->host) {
986 return -EINVAL;
987 }
988
989 if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
990 return -EACCES;
991
992 offset = (loff_t)(start - vma->vm_start)
993 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
994
995 /*
996 * Filesystem's fallocate may need to take i_rwsem. We need to
997 * explicitly grab a reference because the vma (and hence the
998 * vma's reference to the file) can go away as soon as we drop
999 * mmap_lock.
1000 */
1001 get_file(f);
1002 if (userfaultfd_remove(vma, start, end)) {
1003 /* mmap_lock was not released by userfaultfd_remove() */
1004 mmap_read_unlock(mm);
1005 }
1006 error = vfs_fallocate(f,
1007 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
1008 offset, end - start);
1009 fput(f);
1010 mmap_read_lock(mm);
1011 return error;
1012}
1013
1014/*
1015 * Apply an madvise behavior to a region of a vma. madvise_update_vma
1016 * will handle splitting a vm area into separate areas, each area with its own
1017 * behavior.
1018 */
1019static int madvise_vma_behavior(struct vm_area_struct *vma,
1020 struct vm_area_struct **prev,
1021 unsigned long start, unsigned long end,
1022 unsigned long behavior)
1023{
1024 int error;
1025 struct anon_vma_name *anon_name;
1026 unsigned long new_flags = vma->vm_flags;
1027
1028 switch (behavior) {
1029 case MADV_REMOVE:
1030 return madvise_remove(vma, prev, start, end);
1031 case MADV_WILLNEED:
1032 return madvise_willneed(vma, prev, start, end);
1033 case MADV_COLD:
1034 return madvise_cold(vma, prev, start, end);
1035 case MADV_PAGEOUT:
1036 return madvise_pageout(vma, prev, start, end);
1037 case MADV_FREE:
1038 case MADV_DONTNEED:
1039 case MADV_DONTNEED_LOCKED:
1040 return madvise_dontneed_free(vma, prev, start, end, behavior);
1041 case MADV_POPULATE_READ:
1042 case MADV_POPULATE_WRITE:
1043 return madvise_populate(vma, prev, start, end, behavior);
1044 case MADV_NORMAL:
1045 new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
1046 break;
1047 case MADV_SEQUENTIAL:
1048 new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
1049 break;
1050 case MADV_RANDOM:
1051 new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
1052 break;
1053 case MADV_DONTFORK:
1054 new_flags |= VM_DONTCOPY;
1055 break;
1056 case MADV_DOFORK:
1057 if (vma->vm_flags & VM_IO)
1058 return -EINVAL;
1059 new_flags &= ~VM_DONTCOPY;
1060 break;
1061 case MADV_WIPEONFORK:
1062 /* MADV_WIPEONFORK is only supported on anonymous memory. */
1063 if (vma->vm_file || vma->vm_flags & VM_SHARED)
1064 return -EINVAL;
1065 new_flags |= VM_WIPEONFORK;
1066 break;
1067 case MADV_KEEPONFORK:
1068 new_flags &= ~VM_WIPEONFORK;
1069 break;
1070 case MADV_DONTDUMP:
1071 new_flags |= VM_DONTDUMP;
1072 break;
1073 case MADV_DODUMP:
1074 if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL)
1075 return -EINVAL;
1076 new_flags &= ~VM_DONTDUMP;
1077 break;
1078 case MADV_MERGEABLE:
1079 case MADV_UNMERGEABLE:
1080 error = ksm_madvise(vma, start, end, behavior, &new_flags);
1081 if (error)
1082 goto out;
1083 break;
1084 case MADV_HUGEPAGE:
1085 case MADV_NOHUGEPAGE:
1086 error = hugepage_madvise(vma, &new_flags, behavior);
1087 if (error)
1088 goto out;
1089 break;
1090 case MADV_COLLAPSE:
1091 return madvise_collapse(vma, prev, start, end);
1092 }
1093
1094 anon_name = anon_vma_name(vma);
1095 anon_vma_name_get(anon_name);
1096 error = madvise_update_vma(vma, prev, start, end, new_flags,
1097 anon_name);
1098 anon_vma_name_put(anon_name);
1099
1100out:
1101 /*
1102 * madvise() returns EAGAIN if kernel resources, such as
1103 * slab, are temporarily unavailable.
1104 */
1105 if (error == -ENOMEM)
1106 error = -EAGAIN;
1107 return error;
1108}
1109
1110#ifdef CONFIG_MEMORY_FAILURE
1111/*
1112 * Error injection support for memory error handling.
1113 */
1114static int madvise_inject_error(int behavior,
1115 unsigned long start, unsigned long end)
1116{
1117 unsigned long size;
1118
1119 if (!capable(CAP_SYS_ADMIN))
1120 return -EPERM;
1121
1122
1123 for (; start < end; start += size) {
1124 unsigned long pfn;
1125 struct page *page;
1126 int ret;
1127
1128 ret = get_user_pages_fast(start, 1, 0, &page);
1129 if (ret != 1)
1130 return ret;
1131 pfn = page_to_pfn(page);
1132
1133 /*
1134 * When soft offlining hugepages, after migrating the page
1135 * we dissolve it, therefore in the second loop "page" will
1136 * no longer be a compound page.
1137 */
1138 size = page_size(compound_head(page));
1139
1140 if (behavior == MADV_SOFT_OFFLINE) {
1141 pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
1142 pfn, start);
1143 ret = soft_offline_page(pfn, MF_COUNT_INCREASED);
1144 } else {
1145 pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
1146 pfn, start);
1147 ret = memory_failure(pfn, MF_COUNT_INCREASED | MF_SW_SIMULATED);
1148 if (ret == -EOPNOTSUPP)
1149 ret = 0;
1150 }
1151
1152 if (ret)
1153 return ret;
1154 }
1155
1156 return 0;
1157}
1158#endif
1159
1160static bool
1161madvise_behavior_valid(int behavior)
1162{
1163 switch (behavior) {
1164 case MADV_DOFORK:
1165 case MADV_DONTFORK:
1166 case MADV_NORMAL:
1167 case MADV_SEQUENTIAL:
1168 case MADV_RANDOM:
1169 case MADV_REMOVE:
1170 case MADV_WILLNEED:
1171 case MADV_DONTNEED:
1172 case MADV_DONTNEED_LOCKED:
1173 case MADV_FREE:
1174 case MADV_COLD:
1175 case MADV_PAGEOUT:
1176 case MADV_POPULATE_READ:
1177 case MADV_POPULATE_WRITE:
1178#ifdef CONFIG_KSM
1179 case MADV_MERGEABLE:
1180 case MADV_UNMERGEABLE:
1181#endif
1182#ifdef CONFIG_TRANSPARENT_HUGEPAGE
1183 case MADV_HUGEPAGE:
1184 case MADV_NOHUGEPAGE:
1185 case MADV_COLLAPSE:
1186#endif
1187 case MADV_DONTDUMP:
1188 case MADV_DODUMP:
1189 case MADV_WIPEONFORK:
1190 case MADV_KEEPONFORK:
1191#ifdef CONFIG_MEMORY_FAILURE
1192 case MADV_SOFT_OFFLINE:
1193 case MADV_HWPOISON:
1194#endif
1195 return true;
1196
1197 default:
1198 return false;
1199 }
1200}
1201
1202static bool process_madvise_behavior_valid(int behavior)
1203{
1204 switch (behavior) {
1205 case MADV_COLD:
1206 case MADV_PAGEOUT:
1207 case MADV_WILLNEED:
1208 case MADV_COLLAPSE:
1209 return true;
1210 default:
1211 return false;
1212 }
1213}
1214
1215/*
1216 * Walk the vmas in range [start,end), and call the visit function on each one.
1217 * The visit function will get start and end parameters that cover the overlap
1218 * between the current vma and the original range. Any unmapped regions in the
1219 * original range will result in this function returning -ENOMEM while still
1220 * calling the visit function on all of the existing vmas in the range.
1221 * Must be called with the mmap_lock held for reading or writing.
1222 */
1223static
1224int madvise_walk_vmas(struct mm_struct *mm, unsigned long start,
1225 unsigned long end, unsigned long arg,
1226 int (*visit)(struct vm_area_struct *vma,
1227 struct vm_area_struct **prev, unsigned long start,
1228 unsigned long end, unsigned long arg))
1229{
1230 struct vm_area_struct *vma;
1231 struct vm_area_struct *prev;
1232 unsigned long tmp;
1233 int unmapped_error = 0;
1234
1235 /*
1236 * If the interval [start,end) covers some unmapped address
1237 * ranges, just ignore them, but return -ENOMEM at the end.
1238 * - different from the way of handling in mlock etc.
1239 */
1240 vma = find_vma_prev(mm, start, &prev);
1241 if (vma && start > vma->vm_start)
1242 prev = vma;
1243
1244 for (;;) {
1245 int error;
1246
1247 /* Still start < end. */
1248 if (!vma)
1249 return -ENOMEM;
1250
1251 /* Here start < (end|vma->vm_end). */
1252 if (start < vma->vm_start) {
1253 unmapped_error = -ENOMEM;
1254 start = vma->vm_start;
1255 if (start >= end)
1256 break;
1257 }
1258
1259 /* Here vma->vm_start <= start < (end|vma->vm_end) */
1260 tmp = vma->vm_end;
1261 if (end < tmp)
1262 tmp = end;
1263
1264 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
1265 error = visit(vma, &prev, start, tmp, arg);
1266 if (error)
1267 return error;
1268 start = tmp;
1269 if (prev && start < prev->vm_end)
1270 start = prev->vm_end;
1271 if (start >= end)
1272 break;
1273 if (prev)
1274 vma = find_vma(mm, prev->vm_end);
1275 else /* madvise_remove dropped mmap_lock */
1276 vma = find_vma(mm, start);
1277 }
1278
1279 return unmapped_error;
1280}
1281
1282#ifdef CONFIG_ANON_VMA_NAME
1283static int madvise_vma_anon_name(struct vm_area_struct *vma,
1284 struct vm_area_struct **prev,
1285 unsigned long start, unsigned long end,
1286 unsigned long anon_name)
1287{
1288 int error;
1289
1290 /* Only anonymous mappings can be named */
1291 if (vma->vm_file && !vma_is_anon_shmem(vma))
1292 return -EBADF;
1293
1294 error = madvise_update_vma(vma, prev, start, end, vma->vm_flags,
1295 (struct anon_vma_name *)anon_name);
1296
1297 /*
1298 * madvise() returns EAGAIN if kernel resources, such as
1299 * slab, are temporarily unavailable.
1300 */
1301 if (error == -ENOMEM)
1302 error = -EAGAIN;
1303 return error;
1304}
1305
1306int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
1307 unsigned long len_in, struct anon_vma_name *anon_name)
1308{
1309 unsigned long end;
1310 unsigned long len;
1311
1312 if (start & ~PAGE_MASK)
1313 return -EINVAL;
1314 len = (len_in + ~PAGE_MASK) & PAGE_MASK;
1315
1316 /* Check to see whether len was rounded up from small -ve to zero */
1317 if (len_in && !len)
1318 return -EINVAL;
1319
1320 end = start + len;
1321 if (end < start)
1322 return -EINVAL;
1323
1324 if (end == start)
1325 return 0;
1326
1327 return madvise_walk_vmas(mm, start, end, (unsigned long)anon_name,
1328 madvise_vma_anon_name);
1329}
1330#endif /* CONFIG_ANON_VMA_NAME */
1331/*
1332 * The madvise(2) system call.
1333 *
1334 * Applications can use madvise() to advise the kernel how it should
1335 * handle paging I/O in this VM area. The idea is to help the kernel
1336 * use appropriate read-ahead and caching techniques. The information
1337 * provided is advisory only, and can be safely disregarded by the
1338 * kernel without affecting the correct operation of the application.
1339 *
1340 * behavior values:
1341 * MADV_NORMAL - the default behavior is to read clusters. This
1342 * results in some read-ahead and read-behind.
1343 * MADV_RANDOM - the system should read the minimum amount of data
1344 * on any access, since it is unlikely that the appli-
1345 * cation will need more than what it asks for.
1346 * MADV_SEQUENTIAL - pages in the given range will probably be accessed
1347 * once, so they can be aggressively read ahead, and
1348 * can be freed soon after they are accessed.
1349 * MADV_WILLNEED - the application is notifying the system to read
1350 * some pages ahead.
1351 * MADV_DONTNEED - the application is finished with the given range,
1352 * so the kernel can free resources associated with it.
1353 * MADV_FREE - the application marks pages in the given range as lazy free,
1354 * where actual purges are postponed until memory pressure happens.
1355 * MADV_REMOVE - the application wants to free up the given range of
1356 * pages and associated backing store.
1357 * MADV_DONTFORK - omit this area from child's address space when forking:
1358 * typically, to avoid COWing pages pinned by get_user_pages().
1359 * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
1360 * MADV_WIPEONFORK - present the child process with zero-filled memory in this
1361 * range after a fork.
1362 * MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
1363 * MADV_HWPOISON - trigger memory error handler as if the given memory range
1364 * were corrupted by unrecoverable hardware memory failure.
1365 * MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
1366 * MADV_MERGEABLE - the application recommends that KSM try to merge pages in
1367 * this area with pages of identical content from other such areas.
1368 * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
1369 * MADV_HUGEPAGE - the application wants to back the given range by transparent
1370 * huge pages in the future. Existing pages might be coalesced and
1371 * new pages might be allocated as THP.
1372 * MADV_NOHUGEPAGE - mark the given range as not worth being backed by
1373 * transparent huge pages so the existing pages will not be
1374 * coalesced into THP and new pages will not be allocated as THP.
1375 * MADV_COLLAPSE - synchronously coalesce pages into new THP.
1376 * MADV_DONTDUMP - the application wants to prevent pages in the given range
1377 * from being included in its core dump.
1378 * MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
1379 * MADV_COLD - the application is not expected to use this memory soon,
1380 * deactivate pages in this range so that they can be reclaimed
1381 * easily if memory pressure happens.
1382 * MADV_PAGEOUT - the application is not expected to use this memory soon,
1383 * page out the pages in this range immediately.
1384 * MADV_POPULATE_READ - populate (prefault) page tables readable by
1385 * triggering read faults if required
1386 * MADV_POPULATE_WRITE - populate (prefault) page tables writable by
1387 * triggering write faults if required
1388 *
1389 * return values:
1390 * zero - success
1391 * -EINVAL - start + len < 0, start is not page-aligned,
1392 * "behavior" is not a valid value, or application
1393 * is attempting to release locked or shared pages,
1394 * or the specified address range includes file, Huge TLB,
1395 * MAP_SHARED or VMPFNMAP range.
1396 * -ENOMEM - addresses in the specified range are not currently
1397 * mapped, or are outside the AS of the process.
1398 * -EIO - an I/O error occurred while paging in data.
1399 * -EBADF - map exists, but area maps something that isn't a file.
1400 * -EAGAIN - a kernel resource was temporarily unavailable.
1401 */
1402int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior)
1403{
1404 unsigned long end;
1405 int error;
1406 int write;
1407 size_t len;
1408 struct blk_plug plug;
1409
1410 start = untagged_addr(start);
1411
1412 if (!madvise_behavior_valid(behavior))
1413 return -EINVAL;
1414
1415 if (!PAGE_ALIGNED(start))
1416 return -EINVAL;
1417 len = PAGE_ALIGN(len_in);
1418
1419 /* Check to see whether len was rounded up from small -ve to zero */
1420 if (len_in && !len)
1421 return -EINVAL;
1422
1423 end = start + len;
1424 if (end < start)
1425 return -EINVAL;
1426
1427 if (end == start)
1428 return 0;
1429
1430#ifdef CONFIG_MEMORY_FAILURE
1431 if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
1432 return madvise_inject_error(behavior, start, start + len_in);
1433#endif
1434
1435 write = madvise_need_mmap_write(behavior);
1436 if (write) {
1437 if (mmap_write_lock_killable(mm))
1438 return -EINTR;
1439 } else {
1440 mmap_read_lock(mm);
1441 }
1442
1443 blk_start_plug(&plug);
1444 error = madvise_walk_vmas(mm, start, end, behavior,
1445 madvise_vma_behavior);
1446 blk_finish_plug(&plug);
1447 if (write)
1448 mmap_write_unlock(mm);
1449 else
1450 mmap_read_unlock(mm);
1451
1452 return error;
1453}
1454
1455SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
1456{
1457 return do_madvise(current->mm, start, len_in, behavior);
1458}
1459
1460SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec,
1461 size_t, vlen, int, behavior, unsigned int, flags)
1462{
1463 ssize_t ret;
1464 struct iovec iovstack[UIO_FASTIOV], iovec;
1465 struct iovec *iov = iovstack;
1466 struct iov_iter iter;
1467 struct task_struct *task;
1468 struct mm_struct *mm;
1469 size_t total_len;
1470 unsigned int f_flags;
1471
1472 if (flags != 0) {
1473 ret = -EINVAL;
1474 goto out;
1475 }
1476
1477 ret = import_iovec(ITER_DEST, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter);
1478 if (ret < 0)
1479 goto out;
1480
1481 task = pidfd_get_task(pidfd, &f_flags);
1482 if (IS_ERR(task)) {
1483 ret = PTR_ERR(task);
1484 goto free_iov;
1485 }
1486
1487 if (!process_madvise_behavior_valid(behavior)) {
1488 ret = -EINVAL;
1489 goto release_task;
1490 }
1491
1492 /* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */
1493 mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
1494 if (IS_ERR_OR_NULL(mm)) {
1495 ret = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH;
1496 goto release_task;
1497 }
1498
1499 /*
1500 * Require CAP_SYS_NICE for influencing process performance. Note that
1501 * only non-destructive hints are currently supported.
1502 */
1503 if (!capable(CAP_SYS_NICE)) {
1504 ret = -EPERM;
1505 goto release_mm;
1506 }
1507
1508 total_len = iov_iter_count(&iter);
1509
1510 while (iov_iter_count(&iter)) {
1511 iovec = iov_iter_iovec(&iter);
1512 ret = do_madvise(mm, (unsigned long)iovec.iov_base,
1513 iovec.iov_len, behavior);
1514 if (ret < 0)
1515 break;
1516 iov_iter_advance(&iter, iovec.iov_len);
1517 }
1518
1519 ret = (total_len - iov_iter_count(&iter)) ? : ret;
1520
1521release_mm:
1522 mmput(mm);
1523release_task:
1524 put_task_struct(task);
1525free_iov:
1526 kfree(iov);
1527out:
1528 return ret;
1529}