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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/ksm.h>
21#include <linux/fs.h>
22#include <linux/file.h>
23#include <linux/blkdev.h>
24#include <linux/backing-dev.h>
25#include <linux/pagewalk.h>
26#include <linux/swap.h>
27#include <linux/swapops.h>
28#include <linux/shmem_fs.h>
29#include <linux/mmu_notifier.h>
30
31#include <asm/tlb.h>
32
33#include "internal.h"
34
35struct madvise_walk_private {
36 struct mmu_gather *tlb;
37 bool pageout;
38};
39
40/*
41 * Any behaviour which results in changes to the vma->vm_flags needs to
42 * take mmap_sem for writing. Others, which simply traverse vmas, need
43 * to only take it for reading.
44 */
45static int madvise_need_mmap_write(int behavior)
46{
47 switch (behavior) {
48 case MADV_REMOVE:
49 case MADV_WILLNEED:
50 case MADV_DONTNEED:
51 case MADV_COLD:
52 case MADV_PAGEOUT:
53 case MADV_FREE:
54 return 0;
55 default:
56 /* be safe, default to 1. list exceptions explicitly */
57 return 1;
58 }
59}
60
61/*
62 * We can potentially split a vm area into separate
63 * areas, each area with its own behavior.
64 */
65static long madvise_behavior(struct vm_area_struct *vma,
66 struct vm_area_struct **prev,
67 unsigned long start, unsigned long end, int behavior)
68{
69 struct mm_struct *mm = vma->vm_mm;
70 int error = 0;
71 pgoff_t pgoff;
72 unsigned long new_flags = vma->vm_flags;
73
74 switch (behavior) {
75 case MADV_NORMAL:
76 new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
77 break;
78 case MADV_SEQUENTIAL:
79 new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
80 break;
81 case MADV_RANDOM:
82 new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
83 break;
84 case MADV_DONTFORK:
85 new_flags |= VM_DONTCOPY;
86 break;
87 case MADV_DOFORK:
88 if (vma->vm_flags & VM_IO) {
89 error = -EINVAL;
90 goto out;
91 }
92 new_flags &= ~VM_DONTCOPY;
93 break;
94 case MADV_WIPEONFORK:
95 /* MADV_WIPEONFORK is only supported on anonymous memory. */
96 if (vma->vm_file || vma->vm_flags & VM_SHARED) {
97 error = -EINVAL;
98 goto out;
99 }
100 new_flags |= VM_WIPEONFORK;
101 break;
102 case MADV_KEEPONFORK:
103 new_flags &= ~VM_WIPEONFORK;
104 break;
105 case MADV_DONTDUMP:
106 new_flags |= VM_DONTDUMP;
107 break;
108 case MADV_DODUMP:
109 if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL) {
110 error = -EINVAL;
111 goto out;
112 }
113 new_flags &= ~VM_DONTDUMP;
114 break;
115 case MADV_MERGEABLE:
116 case MADV_UNMERGEABLE:
117 error = ksm_madvise(vma, start, end, behavior, &new_flags);
118 if (error)
119 goto out_convert_errno;
120 break;
121 case MADV_HUGEPAGE:
122 case MADV_NOHUGEPAGE:
123 error = hugepage_madvise(vma, &new_flags, behavior);
124 if (error)
125 goto out_convert_errno;
126 break;
127 }
128
129 if (new_flags == vma->vm_flags) {
130 *prev = vma;
131 goto out;
132 }
133
134 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
135 *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
136 vma->vm_file, pgoff, vma_policy(vma),
137 vma->vm_userfaultfd_ctx);
138 if (*prev) {
139 vma = *prev;
140 goto success;
141 }
142
143 *prev = vma;
144
145 if (start != vma->vm_start) {
146 if (unlikely(mm->map_count >= sysctl_max_map_count)) {
147 error = -ENOMEM;
148 goto out;
149 }
150 error = __split_vma(mm, vma, start, 1);
151 if (error)
152 goto out_convert_errno;
153 }
154
155 if (end != vma->vm_end) {
156 if (unlikely(mm->map_count >= sysctl_max_map_count)) {
157 error = -ENOMEM;
158 goto out;
159 }
160 error = __split_vma(mm, vma, end, 0);
161 if (error)
162 goto out_convert_errno;
163 }
164
165success:
166 /*
167 * vm_flags is protected by the mmap_sem held in write mode.
168 */
169 vma->vm_flags = new_flags;
170
171out_convert_errno:
172 /*
173 * madvise() returns EAGAIN if kernel resources, such as
174 * slab, are temporarily unavailable.
175 */
176 if (error == -ENOMEM)
177 error = -EAGAIN;
178out:
179 return error;
180}
181
182#ifdef CONFIG_SWAP
183static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
184 unsigned long end, struct mm_walk *walk)
185{
186 pte_t *orig_pte;
187 struct vm_area_struct *vma = walk->private;
188 unsigned long index;
189
190 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
191 return 0;
192
193 for (index = start; index != end; index += PAGE_SIZE) {
194 pte_t pte;
195 swp_entry_t entry;
196 struct page *page;
197 spinlock_t *ptl;
198
199 orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
200 pte = *(orig_pte + ((index - start) / PAGE_SIZE));
201 pte_unmap_unlock(orig_pte, ptl);
202
203 if (pte_present(pte) || pte_none(pte))
204 continue;
205 entry = pte_to_swp_entry(pte);
206 if (unlikely(non_swap_entry(entry)))
207 continue;
208
209 page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
210 vma, index, false);
211 if (page)
212 put_page(page);
213 }
214
215 return 0;
216}
217
218static const struct mm_walk_ops swapin_walk_ops = {
219 .pmd_entry = swapin_walk_pmd_entry,
220};
221
222static void force_shm_swapin_readahead(struct vm_area_struct *vma,
223 unsigned long start, unsigned long end,
224 struct address_space *mapping)
225{
226 pgoff_t index;
227 struct page *page;
228 swp_entry_t swap;
229
230 for (; start < end; start += PAGE_SIZE) {
231 index = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
232
233 page = find_get_entry(mapping, index);
234 if (!xa_is_value(page)) {
235 if (page)
236 put_page(page);
237 continue;
238 }
239 swap = radix_to_swp_entry(page);
240 page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE,
241 NULL, 0, false);
242 if (page)
243 put_page(page);
244 }
245
246 lru_add_drain(); /* Push any new pages onto the LRU now */
247}
248#endif /* CONFIG_SWAP */
249
250/*
251 * Schedule all required I/O operations. Do not wait for completion.
252 */
253static long madvise_willneed(struct vm_area_struct *vma,
254 struct vm_area_struct **prev,
255 unsigned long start, unsigned long end)
256{
257 struct file *file = vma->vm_file;
258 loff_t offset;
259
260 *prev = vma;
261#ifdef CONFIG_SWAP
262 if (!file) {
263 walk_page_range(vma->vm_mm, start, end, &swapin_walk_ops, vma);
264 lru_add_drain(); /* Push any new pages onto the LRU now */
265 return 0;
266 }
267
268 if (shmem_mapping(file->f_mapping)) {
269 force_shm_swapin_readahead(vma, start, end,
270 file->f_mapping);
271 return 0;
272 }
273#else
274 if (!file)
275 return -EBADF;
276#endif
277
278 if (IS_DAX(file_inode(file))) {
279 /* no bad return value, but ignore advice */
280 return 0;
281 }
282
283 /*
284 * Filesystem's fadvise may need to take various locks. We need to
285 * explicitly grab a reference because the vma (and hence the
286 * vma's reference to the file) can go away as soon as we drop
287 * mmap_sem.
288 */
289 *prev = NULL; /* tell sys_madvise we drop mmap_sem */
290 get_file(file);
291 up_read(¤t->mm->mmap_sem);
292 offset = (loff_t)(start - vma->vm_start)
293 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
294 vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED);
295 fput(file);
296 down_read(¤t->mm->mmap_sem);
297 return 0;
298}
299
300static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
301 unsigned long addr, unsigned long end,
302 struct mm_walk *walk)
303{
304 struct madvise_walk_private *private = walk->private;
305 struct mmu_gather *tlb = private->tlb;
306 bool pageout = private->pageout;
307 struct mm_struct *mm = tlb->mm;
308 struct vm_area_struct *vma = walk->vma;
309 pte_t *orig_pte, *pte, ptent;
310 spinlock_t *ptl;
311 struct page *page = NULL;
312 LIST_HEAD(page_list);
313
314 if (fatal_signal_pending(current))
315 return -EINTR;
316
317#ifdef CONFIG_TRANSPARENT_HUGEPAGE
318 if (pmd_trans_huge(*pmd)) {
319 pmd_t orig_pmd;
320 unsigned long next = pmd_addr_end(addr, end);
321
322 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
323 ptl = pmd_trans_huge_lock(pmd, vma);
324 if (!ptl)
325 return 0;
326
327 orig_pmd = *pmd;
328 if (is_huge_zero_pmd(orig_pmd))
329 goto huge_unlock;
330
331 if (unlikely(!pmd_present(orig_pmd))) {
332 VM_BUG_ON(thp_migration_supported() &&
333 !is_pmd_migration_entry(orig_pmd));
334 goto huge_unlock;
335 }
336
337 page = pmd_page(orig_pmd);
338 if (next - addr != HPAGE_PMD_SIZE) {
339 int err;
340
341 if (page_mapcount(page) != 1)
342 goto huge_unlock;
343
344 get_page(page);
345 spin_unlock(ptl);
346 lock_page(page);
347 err = split_huge_page(page);
348 unlock_page(page);
349 put_page(page);
350 if (!err)
351 goto regular_page;
352 return 0;
353 }
354
355 if (pmd_young(orig_pmd)) {
356 pmdp_invalidate(vma, addr, pmd);
357 orig_pmd = pmd_mkold(orig_pmd);
358
359 set_pmd_at(mm, addr, pmd, orig_pmd);
360 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
361 }
362
363 ClearPageReferenced(page);
364 test_and_clear_page_young(page);
365 if (pageout) {
366 if (!isolate_lru_page(page)) {
367 if (PageUnevictable(page))
368 putback_lru_page(page);
369 else
370 list_add(&page->lru, &page_list);
371 }
372 } else
373 deactivate_page(page);
374huge_unlock:
375 spin_unlock(ptl);
376 if (pageout)
377 reclaim_pages(&page_list);
378 return 0;
379 }
380
381 if (pmd_trans_unstable(pmd))
382 return 0;
383regular_page:
384#endif
385 tlb_change_page_size(tlb, PAGE_SIZE);
386 orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
387 flush_tlb_batched_pending(mm);
388 arch_enter_lazy_mmu_mode();
389 for (; addr < end; pte++, addr += PAGE_SIZE) {
390 ptent = *pte;
391
392 if (pte_none(ptent))
393 continue;
394
395 if (!pte_present(ptent))
396 continue;
397
398 page = vm_normal_page(vma, addr, ptent);
399 if (!page)
400 continue;
401
402 /*
403 * Creating a THP page is expensive so split it only if we
404 * are sure it's worth. Split it if we are only owner.
405 */
406 if (PageTransCompound(page)) {
407 if (page_mapcount(page) != 1)
408 break;
409 get_page(page);
410 if (!trylock_page(page)) {
411 put_page(page);
412 break;
413 }
414 pte_unmap_unlock(orig_pte, ptl);
415 if (split_huge_page(page)) {
416 unlock_page(page);
417 put_page(page);
418 pte_offset_map_lock(mm, pmd, addr, &ptl);
419 break;
420 }
421 unlock_page(page);
422 put_page(page);
423 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
424 pte--;
425 addr -= PAGE_SIZE;
426 continue;
427 }
428
429 VM_BUG_ON_PAGE(PageTransCompound(page), page);
430
431 if (pte_young(ptent)) {
432 ptent = ptep_get_and_clear_full(mm, addr, pte,
433 tlb->fullmm);
434 ptent = pte_mkold(ptent);
435 set_pte_at(mm, addr, pte, ptent);
436 tlb_remove_tlb_entry(tlb, pte, addr);
437 }
438
439 /*
440 * We are deactivating a page for accelerating reclaiming.
441 * VM couldn't reclaim the page unless we clear PG_young.
442 * As a side effect, it makes confuse idle-page tracking
443 * because they will miss recent referenced history.
444 */
445 ClearPageReferenced(page);
446 test_and_clear_page_young(page);
447 if (pageout) {
448 if (!isolate_lru_page(page)) {
449 if (PageUnevictable(page))
450 putback_lru_page(page);
451 else
452 list_add(&page->lru, &page_list);
453 }
454 } else
455 deactivate_page(page);
456 }
457
458 arch_leave_lazy_mmu_mode();
459 pte_unmap_unlock(orig_pte, ptl);
460 if (pageout)
461 reclaim_pages(&page_list);
462 cond_resched();
463
464 return 0;
465}
466
467static const struct mm_walk_ops cold_walk_ops = {
468 .pmd_entry = madvise_cold_or_pageout_pte_range,
469};
470
471static void madvise_cold_page_range(struct mmu_gather *tlb,
472 struct vm_area_struct *vma,
473 unsigned long addr, unsigned long end)
474{
475 struct madvise_walk_private walk_private = {
476 .pageout = false,
477 .tlb = tlb,
478 };
479
480 tlb_start_vma(tlb, vma);
481 walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
482 tlb_end_vma(tlb, vma);
483}
484
485static long madvise_cold(struct vm_area_struct *vma,
486 struct vm_area_struct **prev,
487 unsigned long start_addr, unsigned long end_addr)
488{
489 struct mm_struct *mm = vma->vm_mm;
490 struct mmu_gather tlb;
491
492 *prev = vma;
493 if (!can_madv_lru_vma(vma))
494 return -EINVAL;
495
496 lru_add_drain();
497 tlb_gather_mmu(&tlb, mm, start_addr, end_addr);
498 madvise_cold_page_range(&tlb, vma, start_addr, end_addr);
499 tlb_finish_mmu(&tlb, start_addr, end_addr);
500
501 return 0;
502}
503
504static void madvise_pageout_page_range(struct mmu_gather *tlb,
505 struct vm_area_struct *vma,
506 unsigned long addr, unsigned long end)
507{
508 struct madvise_walk_private walk_private = {
509 .pageout = true,
510 .tlb = tlb,
511 };
512
513 tlb_start_vma(tlb, vma);
514 walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
515 tlb_end_vma(tlb, vma);
516}
517
518static inline bool can_do_pageout(struct vm_area_struct *vma)
519{
520 if (vma_is_anonymous(vma))
521 return true;
522 if (!vma->vm_file)
523 return false;
524 /*
525 * paging out pagecache only for non-anonymous mappings that correspond
526 * to the files the calling process could (if tried) open for writing;
527 * otherwise we'd be including shared non-exclusive mappings, which
528 * opens a side channel.
529 */
530 return inode_owner_or_capable(file_inode(vma->vm_file)) ||
531 inode_permission(file_inode(vma->vm_file), MAY_WRITE) == 0;
532}
533
534static long madvise_pageout(struct vm_area_struct *vma,
535 struct vm_area_struct **prev,
536 unsigned long start_addr, unsigned long end_addr)
537{
538 struct mm_struct *mm = vma->vm_mm;
539 struct mmu_gather tlb;
540
541 *prev = vma;
542 if (!can_madv_lru_vma(vma))
543 return -EINVAL;
544
545 if (!can_do_pageout(vma))
546 return 0;
547
548 lru_add_drain();
549 tlb_gather_mmu(&tlb, mm, start_addr, end_addr);
550 madvise_pageout_page_range(&tlb, vma, start_addr, end_addr);
551 tlb_finish_mmu(&tlb, start_addr, end_addr);
552
553 return 0;
554}
555
556static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
557 unsigned long end, struct mm_walk *walk)
558
559{
560 struct mmu_gather *tlb = walk->private;
561 struct mm_struct *mm = tlb->mm;
562 struct vm_area_struct *vma = walk->vma;
563 spinlock_t *ptl;
564 pte_t *orig_pte, *pte, ptent;
565 struct page *page;
566 int nr_swap = 0;
567 unsigned long next;
568
569 next = pmd_addr_end(addr, end);
570 if (pmd_trans_huge(*pmd))
571 if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next))
572 goto next;
573
574 if (pmd_trans_unstable(pmd))
575 return 0;
576
577 tlb_change_page_size(tlb, PAGE_SIZE);
578 orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
579 flush_tlb_batched_pending(mm);
580 arch_enter_lazy_mmu_mode();
581 for (; addr != end; pte++, addr += PAGE_SIZE) {
582 ptent = *pte;
583
584 if (pte_none(ptent))
585 continue;
586 /*
587 * If the pte has swp_entry, just clear page table to
588 * prevent swap-in which is more expensive rather than
589 * (page allocation + zeroing).
590 */
591 if (!pte_present(ptent)) {
592 swp_entry_t entry;
593
594 entry = pte_to_swp_entry(ptent);
595 if (non_swap_entry(entry))
596 continue;
597 nr_swap--;
598 free_swap_and_cache(entry);
599 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
600 continue;
601 }
602
603 page = vm_normal_page(vma, addr, ptent);
604 if (!page)
605 continue;
606
607 /*
608 * If pmd isn't transhuge but the page is THP and
609 * is owned by only this process, split it and
610 * deactivate all pages.
611 */
612 if (PageTransCompound(page)) {
613 if (page_mapcount(page) != 1)
614 goto out;
615 get_page(page);
616 if (!trylock_page(page)) {
617 put_page(page);
618 goto out;
619 }
620 pte_unmap_unlock(orig_pte, ptl);
621 if (split_huge_page(page)) {
622 unlock_page(page);
623 put_page(page);
624 pte_offset_map_lock(mm, pmd, addr, &ptl);
625 goto out;
626 }
627 unlock_page(page);
628 put_page(page);
629 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
630 pte--;
631 addr -= PAGE_SIZE;
632 continue;
633 }
634
635 VM_BUG_ON_PAGE(PageTransCompound(page), page);
636
637 if (PageSwapCache(page) || PageDirty(page)) {
638 if (!trylock_page(page))
639 continue;
640 /*
641 * If page is shared with others, we couldn't clear
642 * PG_dirty of the page.
643 */
644 if (page_mapcount(page) != 1) {
645 unlock_page(page);
646 continue;
647 }
648
649 if (PageSwapCache(page) && !try_to_free_swap(page)) {
650 unlock_page(page);
651 continue;
652 }
653
654 ClearPageDirty(page);
655 unlock_page(page);
656 }
657
658 if (pte_young(ptent) || pte_dirty(ptent)) {
659 /*
660 * Some of architecture(ex, PPC) don't update TLB
661 * with set_pte_at and tlb_remove_tlb_entry so for
662 * the portability, remap the pte with old|clean
663 * after pte clearing.
664 */
665 ptent = ptep_get_and_clear_full(mm, addr, pte,
666 tlb->fullmm);
667
668 ptent = pte_mkold(ptent);
669 ptent = pte_mkclean(ptent);
670 set_pte_at(mm, addr, pte, ptent);
671 tlb_remove_tlb_entry(tlb, pte, addr);
672 }
673 mark_page_lazyfree(page);
674 }
675out:
676 if (nr_swap) {
677 if (current->mm == mm)
678 sync_mm_rss(mm);
679
680 add_mm_counter(mm, MM_SWAPENTS, nr_swap);
681 }
682 arch_leave_lazy_mmu_mode();
683 pte_unmap_unlock(orig_pte, ptl);
684 cond_resched();
685next:
686 return 0;
687}
688
689static const struct mm_walk_ops madvise_free_walk_ops = {
690 .pmd_entry = madvise_free_pte_range,
691};
692
693static int madvise_free_single_vma(struct vm_area_struct *vma,
694 unsigned long start_addr, unsigned long end_addr)
695{
696 struct mm_struct *mm = vma->vm_mm;
697 struct mmu_notifier_range range;
698 struct mmu_gather tlb;
699
700 /* MADV_FREE works for only anon vma at the moment */
701 if (!vma_is_anonymous(vma))
702 return -EINVAL;
703
704 range.start = max(vma->vm_start, start_addr);
705 if (range.start >= vma->vm_end)
706 return -EINVAL;
707 range.end = min(vma->vm_end, end_addr);
708 if (range.end <= vma->vm_start)
709 return -EINVAL;
710 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm,
711 range.start, range.end);
712
713 lru_add_drain();
714 tlb_gather_mmu(&tlb, mm, range.start, range.end);
715 update_hiwater_rss(mm);
716
717 mmu_notifier_invalidate_range_start(&range);
718 tlb_start_vma(&tlb, vma);
719 walk_page_range(vma->vm_mm, range.start, range.end,
720 &madvise_free_walk_ops, &tlb);
721 tlb_end_vma(&tlb, vma);
722 mmu_notifier_invalidate_range_end(&range);
723 tlb_finish_mmu(&tlb, range.start, range.end);
724
725 return 0;
726}
727
728/*
729 * Application no longer needs these pages. If the pages are dirty,
730 * it's OK to just throw them away. The app will be more careful about
731 * data it wants to keep. Be sure to free swap resources too. The
732 * zap_page_range call sets things up for shrink_active_list to actually free
733 * these pages later if no one else has touched them in the meantime,
734 * although we could add these pages to a global reuse list for
735 * shrink_active_list to pick up before reclaiming other pages.
736 *
737 * NB: This interface discards data rather than pushes it out to swap,
738 * as some implementations do. This has performance implications for
739 * applications like large transactional databases which want to discard
740 * pages in anonymous maps after committing to backing store the data
741 * that was kept in them. There is no reason to write this data out to
742 * the swap area if the application is discarding it.
743 *
744 * An interface that causes the system to free clean pages and flush
745 * dirty pages is already available as msync(MS_INVALIDATE).
746 */
747static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
748 unsigned long start, unsigned long end)
749{
750 zap_page_range(vma, start, end - start);
751 return 0;
752}
753
754static long madvise_dontneed_free(struct vm_area_struct *vma,
755 struct vm_area_struct **prev,
756 unsigned long start, unsigned long end,
757 int behavior)
758{
759 *prev = vma;
760 if (!can_madv_lru_vma(vma))
761 return -EINVAL;
762
763 if (!userfaultfd_remove(vma, start, end)) {
764 *prev = NULL; /* mmap_sem has been dropped, prev is stale */
765
766 down_read(¤t->mm->mmap_sem);
767 vma = find_vma(current->mm, start);
768 if (!vma)
769 return -ENOMEM;
770 if (start < vma->vm_start) {
771 /*
772 * This "vma" under revalidation is the one
773 * with the lowest vma->vm_start where start
774 * is also < vma->vm_end. If start <
775 * vma->vm_start it means an hole materialized
776 * in the user address space within the
777 * virtual range passed to MADV_DONTNEED
778 * or MADV_FREE.
779 */
780 return -ENOMEM;
781 }
782 if (!can_madv_lru_vma(vma))
783 return -EINVAL;
784 if (end > vma->vm_end) {
785 /*
786 * Don't fail if end > vma->vm_end. If the old
787 * vma was splitted while the mmap_sem was
788 * released the effect of the concurrent
789 * operation may not cause madvise() to
790 * have an undefined result. There may be an
791 * adjacent next vma that we'll walk
792 * next. userfaultfd_remove() will generate an
793 * UFFD_EVENT_REMOVE repetition on the
794 * end-vma->vm_end range, but the manager can
795 * handle a repetition fine.
796 */
797 end = vma->vm_end;
798 }
799 VM_WARN_ON(start >= end);
800 }
801
802 if (behavior == MADV_DONTNEED)
803 return madvise_dontneed_single_vma(vma, start, end);
804 else if (behavior == MADV_FREE)
805 return madvise_free_single_vma(vma, start, end);
806 else
807 return -EINVAL;
808}
809
810/*
811 * Application wants to free up the pages and associated backing store.
812 * This is effectively punching a hole into the middle of a file.
813 */
814static long madvise_remove(struct vm_area_struct *vma,
815 struct vm_area_struct **prev,
816 unsigned long start, unsigned long end)
817{
818 loff_t offset;
819 int error;
820 struct file *f;
821
822 *prev = NULL; /* tell sys_madvise we drop mmap_sem */
823
824 if (vma->vm_flags & VM_LOCKED)
825 return -EINVAL;
826
827 f = vma->vm_file;
828
829 if (!f || !f->f_mapping || !f->f_mapping->host) {
830 return -EINVAL;
831 }
832
833 if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
834 return -EACCES;
835
836 offset = (loff_t)(start - vma->vm_start)
837 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
838
839 /*
840 * Filesystem's fallocate may need to take i_mutex. We need to
841 * explicitly grab a reference because the vma (and hence the
842 * vma's reference to the file) can go away as soon as we drop
843 * mmap_sem.
844 */
845 get_file(f);
846 if (userfaultfd_remove(vma, start, end)) {
847 /* mmap_sem was not released by userfaultfd_remove() */
848 up_read(¤t->mm->mmap_sem);
849 }
850 error = vfs_fallocate(f,
851 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
852 offset, end - start);
853 fput(f);
854 down_read(¤t->mm->mmap_sem);
855 return error;
856}
857
858#ifdef CONFIG_MEMORY_FAILURE
859/*
860 * Error injection support for memory error handling.
861 */
862static int madvise_inject_error(int behavior,
863 unsigned long start, unsigned long end)
864{
865 struct page *page;
866 struct zone *zone;
867 unsigned int order;
868
869 if (!capable(CAP_SYS_ADMIN))
870 return -EPERM;
871
872
873 for (; start < end; start += PAGE_SIZE << order) {
874 unsigned long pfn;
875 int ret;
876
877 ret = get_user_pages_fast(start, 1, 0, &page);
878 if (ret != 1)
879 return ret;
880 pfn = page_to_pfn(page);
881
882 /*
883 * When soft offlining hugepages, after migrating the page
884 * we dissolve it, therefore in the second loop "page" will
885 * no longer be a compound page, and order will be 0.
886 */
887 order = compound_order(compound_head(page));
888
889 if (PageHWPoison(page)) {
890 put_page(page);
891 continue;
892 }
893
894 if (behavior == MADV_SOFT_OFFLINE) {
895 pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
896 pfn, start);
897
898 ret = soft_offline_page(page, MF_COUNT_INCREASED);
899 if (ret)
900 return ret;
901 continue;
902 }
903
904 pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
905 pfn, start);
906
907 /*
908 * Drop the page reference taken by get_user_pages_fast(). In
909 * the absence of MF_COUNT_INCREASED the memory_failure()
910 * routine is responsible for pinning the page to prevent it
911 * from being released back to the page allocator.
912 */
913 put_page(page);
914 ret = memory_failure(pfn, 0);
915 if (ret)
916 return ret;
917 }
918
919 /* Ensure that all poisoned pages are removed from per-cpu lists */
920 for_each_populated_zone(zone)
921 drain_all_pages(zone);
922
923 return 0;
924}
925#endif
926
927static long
928madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
929 unsigned long start, unsigned long end, int behavior)
930{
931 switch (behavior) {
932 case MADV_REMOVE:
933 return madvise_remove(vma, prev, start, end);
934 case MADV_WILLNEED:
935 return madvise_willneed(vma, prev, start, end);
936 case MADV_COLD:
937 return madvise_cold(vma, prev, start, end);
938 case MADV_PAGEOUT:
939 return madvise_pageout(vma, prev, start, end);
940 case MADV_FREE:
941 case MADV_DONTNEED:
942 return madvise_dontneed_free(vma, prev, start, end, behavior);
943 default:
944 return madvise_behavior(vma, prev, start, end, behavior);
945 }
946}
947
948static bool
949madvise_behavior_valid(int behavior)
950{
951 switch (behavior) {
952 case MADV_DOFORK:
953 case MADV_DONTFORK:
954 case MADV_NORMAL:
955 case MADV_SEQUENTIAL:
956 case MADV_RANDOM:
957 case MADV_REMOVE:
958 case MADV_WILLNEED:
959 case MADV_DONTNEED:
960 case MADV_FREE:
961 case MADV_COLD:
962 case MADV_PAGEOUT:
963#ifdef CONFIG_KSM
964 case MADV_MERGEABLE:
965 case MADV_UNMERGEABLE:
966#endif
967#ifdef CONFIG_TRANSPARENT_HUGEPAGE
968 case MADV_HUGEPAGE:
969 case MADV_NOHUGEPAGE:
970#endif
971 case MADV_DONTDUMP:
972 case MADV_DODUMP:
973 case MADV_WIPEONFORK:
974 case MADV_KEEPONFORK:
975#ifdef CONFIG_MEMORY_FAILURE
976 case MADV_SOFT_OFFLINE:
977 case MADV_HWPOISON:
978#endif
979 return true;
980
981 default:
982 return false;
983 }
984}
985
986/*
987 * The madvise(2) system call.
988 *
989 * Applications can use madvise() to advise the kernel how it should
990 * handle paging I/O in this VM area. The idea is to help the kernel
991 * use appropriate read-ahead and caching techniques. The information
992 * provided is advisory only, and can be safely disregarded by the
993 * kernel without affecting the correct operation of the application.
994 *
995 * behavior values:
996 * MADV_NORMAL - the default behavior is to read clusters. This
997 * results in some read-ahead and read-behind.
998 * MADV_RANDOM - the system should read the minimum amount of data
999 * on any access, since it is unlikely that the appli-
1000 * cation will need more than what it asks for.
1001 * MADV_SEQUENTIAL - pages in the given range will probably be accessed
1002 * once, so they can be aggressively read ahead, and
1003 * can be freed soon after they are accessed.
1004 * MADV_WILLNEED - the application is notifying the system to read
1005 * some pages ahead.
1006 * MADV_DONTNEED - the application is finished with the given range,
1007 * so the kernel can free resources associated with it.
1008 * MADV_FREE - the application marks pages in the given range as lazy free,
1009 * where actual purges are postponed until memory pressure happens.
1010 * MADV_REMOVE - the application wants to free up the given range of
1011 * pages and associated backing store.
1012 * MADV_DONTFORK - omit this area from child's address space when forking:
1013 * typically, to avoid COWing pages pinned by get_user_pages().
1014 * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
1015 * MADV_WIPEONFORK - present the child process with zero-filled memory in this
1016 * range after a fork.
1017 * MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
1018 * MADV_HWPOISON - trigger memory error handler as if the given memory range
1019 * were corrupted by unrecoverable hardware memory failure.
1020 * MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
1021 * MADV_MERGEABLE - the application recommends that KSM try to merge pages in
1022 * this area with pages of identical content from other such areas.
1023 * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
1024 * MADV_HUGEPAGE - the application wants to back the given range by transparent
1025 * huge pages in the future. Existing pages might be coalesced and
1026 * new pages might be allocated as THP.
1027 * MADV_NOHUGEPAGE - mark the given range as not worth being backed by
1028 * transparent huge pages so the existing pages will not be
1029 * coalesced into THP and new pages will not be allocated as THP.
1030 * MADV_DONTDUMP - the application wants to prevent pages in the given range
1031 * from being included in its core dump.
1032 * MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
1033 *
1034 * return values:
1035 * zero - success
1036 * -EINVAL - start + len < 0, start is not page-aligned,
1037 * "behavior" is not a valid value, or application
1038 * is attempting to release locked or shared pages,
1039 * or the specified address range includes file, Huge TLB,
1040 * MAP_SHARED or VMPFNMAP range.
1041 * -ENOMEM - addresses in the specified range are not currently
1042 * mapped, or are outside the AS of the process.
1043 * -EIO - an I/O error occurred while paging in data.
1044 * -EBADF - map exists, but area maps something that isn't a file.
1045 * -EAGAIN - a kernel resource was temporarily unavailable.
1046 */
1047SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
1048{
1049 unsigned long end, tmp;
1050 struct vm_area_struct *vma, *prev;
1051 int unmapped_error = 0;
1052 int error = -EINVAL;
1053 int write;
1054 size_t len;
1055 struct blk_plug plug;
1056
1057 start = untagged_addr(start);
1058
1059 if (!madvise_behavior_valid(behavior))
1060 return error;
1061
1062 if (start & ~PAGE_MASK)
1063 return error;
1064 len = (len_in + ~PAGE_MASK) & PAGE_MASK;
1065
1066 /* Check to see whether len was rounded up from small -ve to zero */
1067 if (len_in && !len)
1068 return error;
1069
1070 end = start + len;
1071 if (end < start)
1072 return error;
1073
1074 error = 0;
1075 if (end == start)
1076 return error;
1077
1078#ifdef CONFIG_MEMORY_FAILURE
1079 if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
1080 return madvise_inject_error(behavior, start, start + len_in);
1081#endif
1082
1083 write = madvise_need_mmap_write(behavior);
1084 if (write) {
1085 if (down_write_killable(¤t->mm->mmap_sem))
1086 return -EINTR;
1087 } else {
1088 down_read(¤t->mm->mmap_sem);
1089 }
1090
1091 /*
1092 * If the interval [start,end) covers some unmapped address
1093 * ranges, just ignore them, but return -ENOMEM at the end.
1094 * - different from the way of handling in mlock etc.
1095 */
1096 vma = find_vma_prev(current->mm, start, &prev);
1097 if (vma && start > vma->vm_start)
1098 prev = vma;
1099
1100 blk_start_plug(&plug);
1101 for (;;) {
1102 /* Still start < end. */
1103 error = -ENOMEM;
1104 if (!vma)
1105 goto out;
1106
1107 /* Here start < (end|vma->vm_end). */
1108 if (start < vma->vm_start) {
1109 unmapped_error = -ENOMEM;
1110 start = vma->vm_start;
1111 if (start >= end)
1112 goto out;
1113 }
1114
1115 /* Here vma->vm_start <= start < (end|vma->vm_end) */
1116 tmp = vma->vm_end;
1117 if (end < tmp)
1118 tmp = end;
1119
1120 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
1121 error = madvise_vma(vma, &prev, start, tmp, behavior);
1122 if (error)
1123 goto out;
1124 start = tmp;
1125 if (prev && start < prev->vm_end)
1126 start = prev->vm_end;
1127 error = unmapped_error;
1128 if (start >= end)
1129 goto out;
1130 if (prev)
1131 vma = prev->vm_next;
1132 else /* madvise_remove dropped mmap_sem */
1133 vma = find_vma(current->mm, start);
1134 }
1135out:
1136 blk_finish_plug(&plug);
1137 if (write)
1138 up_write(¤t->mm->mmap_sem);
1139 else
1140 up_read(¤t->mm->mmap_sem);
1141
1142 return error;
1143}
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/userfaultfd_k.h>
15#include <linux/hugetlb.h>
16#include <linux/falloc.h>
17#include <linux/sched.h>
18#include <linux/ksm.h>
19#include <linux/fs.h>
20#include <linux/file.h>
21#include <linux/blkdev.h>
22#include <linux/backing-dev.h>
23#include <linux/swap.h>
24#include <linux/swapops.h>
25#include <linux/shmem_fs.h>
26#include <linux/mmu_notifier.h>
27
28#include <asm/tlb.h>
29
30#include "internal.h"
31
32/*
33 * Any behaviour which results in changes to the vma->vm_flags needs to
34 * take mmap_sem for writing. Others, which simply traverse vmas, need
35 * to only take it for reading.
36 */
37static int madvise_need_mmap_write(int behavior)
38{
39 switch (behavior) {
40 case MADV_REMOVE:
41 case MADV_WILLNEED:
42 case MADV_DONTNEED:
43 case MADV_FREE:
44 return 0;
45 default:
46 /* be safe, default to 1. list exceptions explicitly */
47 return 1;
48 }
49}
50
51/*
52 * We can potentially split a vm area into separate
53 * areas, each area with its own behavior.
54 */
55static long madvise_behavior(struct vm_area_struct *vma,
56 struct vm_area_struct **prev,
57 unsigned long start, unsigned long end, int behavior)
58{
59 struct mm_struct *mm = vma->vm_mm;
60 int error = 0;
61 pgoff_t pgoff;
62 unsigned long new_flags = vma->vm_flags;
63
64 switch (behavior) {
65 case MADV_NORMAL:
66 new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
67 break;
68 case MADV_SEQUENTIAL:
69 new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
70 break;
71 case MADV_RANDOM:
72 new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
73 break;
74 case MADV_DONTFORK:
75 new_flags |= VM_DONTCOPY;
76 break;
77 case MADV_DOFORK:
78 if (vma->vm_flags & VM_IO) {
79 error = -EINVAL;
80 goto out;
81 }
82 new_flags &= ~VM_DONTCOPY;
83 break;
84 case MADV_WIPEONFORK:
85 /* MADV_WIPEONFORK is only supported on anonymous memory. */
86 if (vma->vm_file || vma->vm_flags & VM_SHARED) {
87 error = -EINVAL;
88 goto out;
89 }
90 new_flags |= VM_WIPEONFORK;
91 break;
92 case MADV_KEEPONFORK:
93 new_flags &= ~VM_WIPEONFORK;
94 break;
95 case MADV_DONTDUMP:
96 new_flags |= VM_DONTDUMP;
97 break;
98 case MADV_DODUMP:
99 if (new_flags & VM_SPECIAL) {
100 error = -EINVAL;
101 goto out;
102 }
103 new_flags &= ~VM_DONTDUMP;
104 break;
105 case MADV_MERGEABLE:
106 case MADV_UNMERGEABLE:
107 error = ksm_madvise(vma, start, end, behavior, &new_flags);
108 if (error) {
109 /*
110 * madvise() returns EAGAIN if kernel resources, such as
111 * slab, are temporarily unavailable.
112 */
113 if (error == -ENOMEM)
114 error = -EAGAIN;
115 goto out;
116 }
117 break;
118 case MADV_HUGEPAGE:
119 case MADV_NOHUGEPAGE:
120 error = hugepage_madvise(vma, &new_flags, behavior);
121 if (error) {
122 /*
123 * madvise() returns EAGAIN if kernel resources, such as
124 * slab, are temporarily unavailable.
125 */
126 if (error == -ENOMEM)
127 error = -EAGAIN;
128 goto out;
129 }
130 break;
131 }
132
133 if (new_flags == vma->vm_flags) {
134 *prev = vma;
135 goto out;
136 }
137
138 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
139 *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
140 vma->vm_file, pgoff, vma_policy(vma),
141 vma->vm_userfaultfd_ctx);
142 if (*prev) {
143 vma = *prev;
144 goto success;
145 }
146
147 *prev = vma;
148
149 if (start != vma->vm_start) {
150 if (unlikely(mm->map_count >= sysctl_max_map_count)) {
151 error = -ENOMEM;
152 goto out;
153 }
154 error = __split_vma(mm, vma, start, 1);
155 if (error) {
156 /*
157 * madvise() returns EAGAIN if kernel resources, such as
158 * slab, are temporarily unavailable.
159 */
160 if (error == -ENOMEM)
161 error = -EAGAIN;
162 goto out;
163 }
164 }
165
166 if (end != vma->vm_end) {
167 if (unlikely(mm->map_count >= sysctl_max_map_count)) {
168 error = -ENOMEM;
169 goto out;
170 }
171 error = __split_vma(mm, vma, end, 0);
172 if (error) {
173 /*
174 * madvise() returns EAGAIN if kernel resources, such as
175 * slab, are temporarily unavailable.
176 */
177 if (error == -ENOMEM)
178 error = -EAGAIN;
179 goto out;
180 }
181 }
182
183success:
184 /*
185 * vm_flags is protected by the mmap_sem held in write mode.
186 */
187 vma->vm_flags = new_flags;
188out:
189 return error;
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 pte_t *orig_pte;
197 struct vm_area_struct *vma = walk->private;
198 unsigned long index;
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
209 orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
210 pte = *(orig_pte + ((index - start) / PAGE_SIZE));
211 pte_unmap_unlock(orig_pte, ptl);
212
213 if (pte_present(pte) || pte_none(pte))
214 continue;
215 entry = pte_to_swp_entry(pte);
216 if (unlikely(non_swap_entry(entry)))
217 continue;
218
219 page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
220 vma, index, false);
221 if (page)
222 put_page(page);
223 }
224
225 return 0;
226}
227
228static void force_swapin_readahead(struct vm_area_struct *vma,
229 unsigned long start, unsigned long end)
230{
231 struct mm_walk walk = {
232 .mm = vma->vm_mm,
233 .pmd_entry = swapin_walk_pmd_entry,
234 .private = vma,
235 };
236
237 walk_page_range(start, end, &walk);
238
239 lru_add_drain(); /* Push any new pages onto the LRU now */
240}
241
242static void force_shm_swapin_readahead(struct vm_area_struct *vma,
243 unsigned long start, unsigned long end,
244 struct address_space *mapping)
245{
246 pgoff_t index;
247 struct page *page;
248 swp_entry_t swap;
249
250 for (; start < end; start += PAGE_SIZE) {
251 index = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
252
253 page = find_get_entry(mapping, index);
254 if (!radix_tree_exceptional_entry(page)) {
255 if (page)
256 put_page(page);
257 continue;
258 }
259 swap = radix_to_swp_entry(page);
260 page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE,
261 NULL, 0, false);
262 if (page)
263 put_page(page);
264 }
265
266 lru_add_drain(); /* Push any new pages onto the LRU now */
267}
268#endif /* CONFIG_SWAP */
269
270/*
271 * Schedule all required I/O operations. Do not wait for completion.
272 */
273static long madvise_willneed(struct vm_area_struct *vma,
274 struct vm_area_struct **prev,
275 unsigned long start, unsigned long end)
276{
277 struct file *file = vma->vm_file;
278
279 *prev = vma;
280#ifdef CONFIG_SWAP
281 if (!file) {
282 force_swapin_readahead(vma, start, end);
283 return 0;
284 }
285
286 if (shmem_mapping(file->f_mapping)) {
287 force_shm_swapin_readahead(vma, start, end,
288 file->f_mapping);
289 return 0;
290 }
291#else
292 if (!file)
293 return -EBADF;
294#endif
295
296 if (IS_DAX(file_inode(file))) {
297 /* no bad return value, but ignore advice */
298 return 0;
299 }
300
301 start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
302 if (end > vma->vm_end)
303 end = vma->vm_end;
304 end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
305
306 force_page_cache_readahead(file->f_mapping, file, start, end - start);
307 return 0;
308}
309
310static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
311 unsigned long end, struct mm_walk *walk)
312
313{
314 struct mmu_gather *tlb = walk->private;
315 struct mm_struct *mm = tlb->mm;
316 struct vm_area_struct *vma = walk->vma;
317 spinlock_t *ptl;
318 pte_t *orig_pte, *pte, ptent;
319 struct page *page;
320 int nr_swap = 0;
321 unsigned long next;
322
323 next = pmd_addr_end(addr, end);
324 if (pmd_trans_huge(*pmd))
325 if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next))
326 goto next;
327
328 if (pmd_trans_unstable(pmd))
329 return 0;
330
331 tlb_remove_check_page_size_change(tlb, PAGE_SIZE);
332 orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
333 flush_tlb_batched_pending(mm);
334 arch_enter_lazy_mmu_mode();
335 for (; addr != end; pte++, addr += PAGE_SIZE) {
336 ptent = *pte;
337
338 if (pte_none(ptent))
339 continue;
340 /*
341 * If the pte has swp_entry, just clear page table to
342 * prevent swap-in which is more expensive rather than
343 * (page allocation + zeroing).
344 */
345 if (!pte_present(ptent)) {
346 swp_entry_t entry;
347
348 entry = pte_to_swp_entry(ptent);
349 if (non_swap_entry(entry))
350 continue;
351 nr_swap--;
352 free_swap_and_cache(entry);
353 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
354 continue;
355 }
356
357 page = _vm_normal_page(vma, addr, ptent, true);
358 if (!page)
359 continue;
360
361 /*
362 * If pmd isn't transhuge but the page is THP and
363 * is owned by only this process, split it and
364 * deactivate all pages.
365 */
366 if (PageTransCompound(page)) {
367 if (page_mapcount(page) != 1)
368 goto out;
369 get_page(page);
370 if (!trylock_page(page)) {
371 put_page(page);
372 goto out;
373 }
374 pte_unmap_unlock(orig_pte, ptl);
375 if (split_huge_page(page)) {
376 unlock_page(page);
377 put_page(page);
378 pte_offset_map_lock(mm, pmd, addr, &ptl);
379 goto out;
380 }
381 unlock_page(page);
382 put_page(page);
383 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
384 pte--;
385 addr -= PAGE_SIZE;
386 continue;
387 }
388
389 VM_BUG_ON_PAGE(PageTransCompound(page), page);
390
391 if (PageSwapCache(page) || PageDirty(page)) {
392 if (!trylock_page(page))
393 continue;
394 /*
395 * If page is shared with others, we couldn't clear
396 * PG_dirty of the page.
397 */
398 if (page_mapcount(page) != 1) {
399 unlock_page(page);
400 continue;
401 }
402
403 if (PageSwapCache(page) && !try_to_free_swap(page)) {
404 unlock_page(page);
405 continue;
406 }
407
408 ClearPageDirty(page);
409 unlock_page(page);
410 }
411
412 if (pte_young(ptent) || pte_dirty(ptent)) {
413 /*
414 * Some of architecture(ex, PPC) don't update TLB
415 * with set_pte_at and tlb_remove_tlb_entry so for
416 * the portability, remap the pte with old|clean
417 * after pte clearing.
418 */
419 ptent = ptep_get_and_clear_full(mm, addr, pte,
420 tlb->fullmm);
421
422 ptent = pte_mkold(ptent);
423 ptent = pte_mkclean(ptent);
424 set_pte_at(mm, addr, pte, ptent);
425 tlb_remove_tlb_entry(tlb, pte, addr);
426 }
427 mark_page_lazyfree(page);
428 }
429out:
430 if (nr_swap) {
431 if (current->mm == mm)
432 sync_mm_rss(mm);
433
434 add_mm_counter(mm, MM_SWAPENTS, nr_swap);
435 }
436 arch_leave_lazy_mmu_mode();
437 pte_unmap_unlock(orig_pte, ptl);
438 cond_resched();
439next:
440 return 0;
441}
442
443static void madvise_free_page_range(struct mmu_gather *tlb,
444 struct vm_area_struct *vma,
445 unsigned long addr, unsigned long end)
446{
447 struct mm_walk free_walk = {
448 .pmd_entry = madvise_free_pte_range,
449 .mm = vma->vm_mm,
450 .private = tlb,
451 };
452
453 tlb_start_vma(tlb, vma);
454 walk_page_range(addr, end, &free_walk);
455 tlb_end_vma(tlb, vma);
456}
457
458static int madvise_free_single_vma(struct vm_area_struct *vma,
459 unsigned long start_addr, unsigned long end_addr)
460{
461 unsigned long start, end;
462 struct mm_struct *mm = vma->vm_mm;
463 struct mmu_gather tlb;
464
465 /* MADV_FREE works for only anon vma at the moment */
466 if (!vma_is_anonymous(vma))
467 return -EINVAL;
468
469 start = max(vma->vm_start, start_addr);
470 if (start >= vma->vm_end)
471 return -EINVAL;
472 end = min(vma->vm_end, end_addr);
473 if (end <= vma->vm_start)
474 return -EINVAL;
475
476 lru_add_drain();
477 tlb_gather_mmu(&tlb, mm, start, end);
478 update_hiwater_rss(mm);
479
480 mmu_notifier_invalidate_range_start(mm, start, end);
481 madvise_free_page_range(&tlb, vma, start, end);
482 mmu_notifier_invalidate_range_end(mm, start, end);
483 tlb_finish_mmu(&tlb, start, end);
484
485 return 0;
486}
487
488/*
489 * Application no longer needs these pages. If the pages are dirty,
490 * it's OK to just throw them away. The app will be more careful about
491 * data it wants to keep. Be sure to free swap resources too. The
492 * zap_page_range call sets things up for shrink_active_list to actually free
493 * these pages later if no one else has touched them in the meantime,
494 * although we could add these pages to a global reuse list for
495 * shrink_active_list to pick up before reclaiming other pages.
496 *
497 * NB: This interface discards data rather than pushes it out to swap,
498 * as some implementations do. This has performance implications for
499 * applications like large transactional databases which want to discard
500 * pages in anonymous maps after committing to backing store the data
501 * that was kept in them. There is no reason to write this data out to
502 * the swap area if the application is discarding it.
503 *
504 * An interface that causes the system to free clean pages and flush
505 * dirty pages is already available as msync(MS_INVALIDATE).
506 */
507static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
508 unsigned long start, unsigned long end)
509{
510 zap_page_range(vma, start, end - start);
511 return 0;
512}
513
514static long madvise_dontneed_free(struct vm_area_struct *vma,
515 struct vm_area_struct **prev,
516 unsigned long start, unsigned long end,
517 int behavior)
518{
519 *prev = vma;
520 if (!can_madv_dontneed_vma(vma))
521 return -EINVAL;
522
523 if (!userfaultfd_remove(vma, start, end)) {
524 *prev = NULL; /* mmap_sem has been dropped, prev is stale */
525
526 down_read(¤t->mm->mmap_sem);
527 vma = find_vma(current->mm, start);
528 if (!vma)
529 return -ENOMEM;
530 if (start < vma->vm_start) {
531 /*
532 * This "vma" under revalidation is the one
533 * with the lowest vma->vm_start where start
534 * is also < vma->vm_end. If start <
535 * vma->vm_start it means an hole materialized
536 * in the user address space within the
537 * virtual range passed to MADV_DONTNEED
538 * or MADV_FREE.
539 */
540 return -ENOMEM;
541 }
542 if (!can_madv_dontneed_vma(vma))
543 return -EINVAL;
544 if (end > vma->vm_end) {
545 /*
546 * Don't fail if end > vma->vm_end. If the old
547 * vma was splitted while the mmap_sem was
548 * released the effect of the concurrent
549 * operation may not cause madvise() to
550 * have an undefined result. There may be an
551 * adjacent next vma that we'll walk
552 * next. userfaultfd_remove() will generate an
553 * UFFD_EVENT_REMOVE repetition on the
554 * end-vma->vm_end range, but the manager can
555 * handle a repetition fine.
556 */
557 end = vma->vm_end;
558 }
559 VM_WARN_ON(start >= end);
560 }
561
562 if (behavior == MADV_DONTNEED)
563 return madvise_dontneed_single_vma(vma, start, end);
564 else if (behavior == MADV_FREE)
565 return madvise_free_single_vma(vma, start, end);
566 else
567 return -EINVAL;
568}
569
570/*
571 * Application wants to free up the pages and associated backing store.
572 * This is effectively punching a hole into the middle of a file.
573 */
574static long madvise_remove(struct vm_area_struct *vma,
575 struct vm_area_struct **prev,
576 unsigned long start, unsigned long end)
577{
578 loff_t offset;
579 int error;
580 struct file *f;
581
582 *prev = NULL; /* tell sys_madvise we drop mmap_sem */
583
584 if (vma->vm_flags & VM_LOCKED)
585 return -EINVAL;
586
587 f = vma->vm_file;
588
589 if (!f || !f->f_mapping || !f->f_mapping->host) {
590 return -EINVAL;
591 }
592
593 if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
594 return -EACCES;
595
596 offset = (loff_t)(start - vma->vm_start)
597 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
598
599 /*
600 * Filesystem's fallocate may need to take i_mutex. We need to
601 * explicitly grab a reference because the vma (and hence the
602 * vma's reference to the file) can go away as soon as we drop
603 * mmap_sem.
604 */
605 get_file(f);
606 if (userfaultfd_remove(vma, start, end)) {
607 /* mmap_sem was not released by userfaultfd_remove() */
608 up_read(¤t->mm->mmap_sem);
609 }
610 error = vfs_fallocate(f,
611 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
612 offset, end - start);
613 fput(f);
614 down_read(¤t->mm->mmap_sem);
615 return error;
616}
617
618#ifdef CONFIG_MEMORY_FAILURE
619/*
620 * Error injection support for memory error handling.
621 */
622static int madvise_inject_error(int behavior,
623 unsigned long start, unsigned long end)
624{
625 struct page *page;
626 struct zone *zone;
627 unsigned int order;
628
629 if (!capable(CAP_SYS_ADMIN))
630 return -EPERM;
631
632
633 for (; start < end; start += PAGE_SIZE << order) {
634 int ret;
635
636 ret = get_user_pages_fast(start, 1, 0, &page);
637 if (ret != 1)
638 return ret;
639
640 /*
641 * When soft offlining hugepages, after migrating the page
642 * we dissolve it, therefore in the second loop "page" will
643 * no longer be a compound page, and order will be 0.
644 */
645 order = compound_order(compound_head(page));
646
647 if (PageHWPoison(page)) {
648 put_page(page);
649 continue;
650 }
651
652 if (behavior == MADV_SOFT_OFFLINE) {
653 pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
654 page_to_pfn(page), start);
655
656 ret = soft_offline_page(page, MF_COUNT_INCREASED);
657 if (ret)
658 return ret;
659 continue;
660 }
661 pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
662 page_to_pfn(page), start);
663
664 ret = memory_failure(page_to_pfn(page), MF_COUNT_INCREASED);
665 if (ret)
666 return ret;
667 }
668
669 /* Ensure that all poisoned pages are removed from per-cpu lists */
670 for_each_populated_zone(zone)
671 drain_all_pages(zone);
672
673 return 0;
674}
675#endif
676
677static long
678madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
679 unsigned long start, unsigned long end, int behavior)
680{
681 switch (behavior) {
682 case MADV_REMOVE:
683 return madvise_remove(vma, prev, start, end);
684 case MADV_WILLNEED:
685 return madvise_willneed(vma, prev, start, end);
686 case MADV_FREE:
687 case MADV_DONTNEED:
688 return madvise_dontneed_free(vma, prev, start, end, behavior);
689 default:
690 return madvise_behavior(vma, prev, start, end, behavior);
691 }
692}
693
694static bool
695madvise_behavior_valid(int behavior)
696{
697 switch (behavior) {
698 case MADV_DOFORK:
699 case MADV_DONTFORK:
700 case MADV_NORMAL:
701 case MADV_SEQUENTIAL:
702 case MADV_RANDOM:
703 case MADV_REMOVE:
704 case MADV_WILLNEED:
705 case MADV_DONTNEED:
706 case MADV_FREE:
707#ifdef CONFIG_KSM
708 case MADV_MERGEABLE:
709 case MADV_UNMERGEABLE:
710#endif
711#ifdef CONFIG_TRANSPARENT_HUGEPAGE
712 case MADV_HUGEPAGE:
713 case MADV_NOHUGEPAGE:
714#endif
715 case MADV_DONTDUMP:
716 case MADV_DODUMP:
717 case MADV_WIPEONFORK:
718 case MADV_KEEPONFORK:
719#ifdef CONFIG_MEMORY_FAILURE
720 case MADV_SOFT_OFFLINE:
721 case MADV_HWPOISON:
722#endif
723 return true;
724
725 default:
726 return false;
727 }
728}
729
730/*
731 * The madvise(2) system call.
732 *
733 * Applications can use madvise() to advise the kernel how it should
734 * handle paging I/O in this VM area. The idea is to help the kernel
735 * use appropriate read-ahead and caching techniques. The information
736 * provided is advisory only, and can be safely disregarded by the
737 * kernel without affecting the correct operation of the application.
738 *
739 * behavior values:
740 * MADV_NORMAL - the default behavior is to read clusters. This
741 * results in some read-ahead and read-behind.
742 * MADV_RANDOM - the system should read the minimum amount of data
743 * on any access, since it is unlikely that the appli-
744 * cation will need more than what it asks for.
745 * MADV_SEQUENTIAL - pages in the given range will probably be accessed
746 * once, so they can be aggressively read ahead, and
747 * can be freed soon after they are accessed.
748 * MADV_WILLNEED - the application is notifying the system to read
749 * some pages ahead.
750 * MADV_DONTNEED - the application is finished with the given range,
751 * so the kernel can free resources associated with it.
752 * MADV_FREE - the application marks pages in the given range as lazy free,
753 * where actual purges are postponed until memory pressure happens.
754 * MADV_REMOVE - the application wants to free up the given range of
755 * pages and associated backing store.
756 * MADV_DONTFORK - omit this area from child's address space when forking:
757 * typically, to avoid COWing pages pinned by get_user_pages().
758 * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
759 * MADV_WIPEONFORK - present the child process with zero-filled memory in this
760 * range after a fork.
761 * MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
762 * MADV_HWPOISON - trigger memory error handler as if the given memory range
763 * were corrupted by unrecoverable hardware memory failure.
764 * MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
765 * MADV_MERGEABLE - the application recommends that KSM try to merge pages in
766 * this area with pages of identical content from other such areas.
767 * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
768 * MADV_HUGEPAGE - the application wants to back the given range by transparent
769 * huge pages in the future. Existing pages might be coalesced and
770 * new pages might be allocated as THP.
771 * MADV_NOHUGEPAGE - mark the given range as not worth being backed by
772 * transparent huge pages so the existing pages will not be
773 * coalesced into THP and new pages will not be allocated as THP.
774 * MADV_DONTDUMP - the application wants to prevent pages in the given range
775 * from being included in its core dump.
776 * MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
777 *
778 * return values:
779 * zero - success
780 * -EINVAL - start + len < 0, start is not page-aligned,
781 * "behavior" is not a valid value, or application
782 * is attempting to release locked or shared pages,
783 * or the specified address range includes file, Huge TLB,
784 * MAP_SHARED or VMPFNMAP range.
785 * -ENOMEM - addresses in the specified range are not currently
786 * mapped, or are outside the AS of the process.
787 * -EIO - an I/O error occurred while paging in data.
788 * -EBADF - map exists, but area maps something that isn't a file.
789 * -EAGAIN - a kernel resource was temporarily unavailable.
790 */
791SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
792{
793 unsigned long end, tmp;
794 struct vm_area_struct *vma, *prev;
795 int unmapped_error = 0;
796 int error = -EINVAL;
797 int write;
798 size_t len;
799 struct blk_plug plug;
800
801 if (!madvise_behavior_valid(behavior))
802 return error;
803
804 if (start & ~PAGE_MASK)
805 return error;
806 len = (len_in + ~PAGE_MASK) & PAGE_MASK;
807
808 /* Check to see whether len was rounded up from small -ve to zero */
809 if (len_in && !len)
810 return error;
811
812 end = start + len;
813 if (end < start)
814 return error;
815
816 error = 0;
817 if (end == start)
818 return error;
819
820#ifdef CONFIG_MEMORY_FAILURE
821 if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
822 return madvise_inject_error(behavior, start, start + len_in);
823#endif
824
825 write = madvise_need_mmap_write(behavior);
826 if (write) {
827 if (down_write_killable(¤t->mm->mmap_sem))
828 return -EINTR;
829 } else {
830 down_read(¤t->mm->mmap_sem);
831 }
832
833 /*
834 * If the interval [start,end) covers some unmapped address
835 * ranges, just ignore them, but return -ENOMEM at the end.
836 * - different from the way of handling in mlock etc.
837 */
838 vma = find_vma_prev(current->mm, start, &prev);
839 if (vma && start > vma->vm_start)
840 prev = vma;
841
842 blk_start_plug(&plug);
843 for (;;) {
844 /* Still start < end. */
845 error = -ENOMEM;
846 if (!vma)
847 goto out;
848
849 /* Here start < (end|vma->vm_end). */
850 if (start < vma->vm_start) {
851 unmapped_error = -ENOMEM;
852 start = vma->vm_start;
853 if (start >= end)
854 goto out;
855 }
856
857 /* Here vma->vm_start <= start < (end|vma->vm_end) */
858 tmp = vma->vm_end;
859 if (end < tmp)
860 tmp = end;
861
862 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
863 error = madvise_vma(vma, &prev, start, tmp, behavior);
864 if (error)
865 goto out;
866 start = tmp;
867 if (prev && start < prev->vm_end)
868 start = prev->vm_end;
869 error = unmapped_error;
870 if (start >= end)
871 goto out;
872 if (prev)
873 vma = prev->vm_next;
874 else /* madvise_remove dropped mmap_sem */
875 vma = find_vma(current->mm, start);
876 }
877out:
878 blk_finish_plug(&plug);
879 if (write)
880 up_write(¤t->mm->mmap_sem);
881 else
882 up_read(¤t->mm->mmap_sem);
883
884 return error;
885}