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