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