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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/mm/madvise.c
4 *
5 * Copyright (C) 1999 Linus Torvalds
6 * Copyright (C) 2002 Christoph Hellwig
7 */
8
9#include <linux/mman.h>
10#include <linux/pagemap.h>
11#include <linux/syscalls.h>
12#include <linux/mempolicy.h>
13#include <linux/page-isolation.h>
14#include <linux/page_idle.h>
15#include <linux/userfaultfd_k.h>
16#include <linux/hugetlb.h>
17#include <linux/falloc.h>
18#include <linux/fadvise.h>
19#include <linux/sched.h>
20#include <linux/sched/mm.h>
21#include <linux/mm_inline.h>
22#include <linux/string.h>
23#include <linux/uio.h>
24#include <linux/ksm.h>
25#include <linux/fs.h>
26#include <linux/file.h>
27#include <linux/blkdev.h>
28#include <linux/backing-dev.h>
29#include <linux/pagewalk.h>
30#include <linux/swap.h>
31#include <linux/swapops.h>
32#include <linux/shmem_fs.h>
33#include <linux/mmu_notifier.h>
34
35#include <asm/tlb.h>
36
37#include "internal.h"
38#include "swap.h"
39
40struct madvise_walk_private {
41 struct mmu_gather *tlb;
42 bool pageout;
43};
44
45/*
46 * Any behaviour which results in changes to the vma->vm_flags needs to
47 * take mmap_lock for writing. Others, which simply traverse vmas, need
48 * to only take it for reading.
49 */
50static int madvise_need_mmap_write(int behavior)
51{
52 switch (behavior) {
53 case MADV_REMOVE:
54 case MADV_WILLNEED:
55 case MADV_DONTNEED:
56 case MADV_DONTNEED_LOCKED:
57 case MADV_COLD:
58 case MADV_PAGEOUT:
59 case MADV_FREE:
60 case MADV_POPULATE_READ:
61 case MADV_POPULATE_WRITE:
62 case MADV_COLLAPSE:
63 return 0;
64 default:
65 /* be safe, default to 1. list exceptions explicitly */
66 return 1;
67 }
68}
69
70#ifdef CONFIG_ANON_VMA_NAME
71struct anon_vma_name *anon_vma_name_alloc(const char *name)
72{
73 struct anon_vma_name *anon_name;
74 size_t count;
75
76 /* Add 1 for NUL terminator at the end of the anon_name->name */
77 count = strlen(name) + 1;
78 anon_name = kmalloc(struct_size(anon_name, name, count), GFP_KERNEL);
79 if (anon_name) {
80 kref_init(&anon_name->kref);
81 memcpy(anon_name->name, name, count);
82 }
83
84 return anon_name;
85}
86
87void anon_vma_name_free(struct kref *kref)
88{
89 struct anon_vma_name *anon_name =
90 container_of(kref, struct anon_vma_name, kref);
91 kfree(anon_name);
92}
93
94struct anon_vma_name *anon_vma_name(struct vm_area_struct *vma)
95{
96 mmap_assert_locked(vma->vm_mm);
97
98 return vma->anon_name;
99}
100
101/* mmap_lock should be write-locked */
102static int replace_anon_vma_name(struct vm_area_struct *vma,
103 struct anon_vma_name *anon_name)
104{
105 struct anon_vma_name *orig_name = anon_vma_name(vma);
106
107 if (!anon_name) {
108 vma->anon_name = NULL;
109 anon_vma_name_put(orig_name);
110 return 0;
111 }
112
113 if (anon_vma_name_eq(orig_name, anon_name))
114 return 0;
115
116 vma->anon_name = anon_vma_name_reuse(anon_name);
117 anon_vma_name_put(orig_name);
118
119 return 0;
120}
121#else /* CONFIG_ANON_VMA_NAME */
122static int replace_anon_vma_name(struct vm_area_struct *vma,
123 struct anon_vma_name *anon_name)
124{
125 if (anon_name)
126 return -EINVAL;
127
128 return 0;
129}
130#endif /* CONFIG_ANON_VMA_NAME */
131/*
132 * Update the vm_flags on region of a vma, splitting it or merging it as
133 * necessary. Must be called with mmap_lock held for writing;
134 * Caller should ensure anon_name stability by raising its refcount even when
135 * anon_name belongs to a valid vma because this function might free that vma.
136 */
137static int madvise_update_vma(struct vm_area_struct *vma,
138 struct vm_area_struct **prev, unsigned long start,
139 unsigned long end, unsigned long new_flags,
140 struct anon_vma_name *anon_name)
141{
142 struct mm_struct *mm = vma->vm_mm;
143 int error;
144 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}
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/mm/madvise.c
4 *
5 * Copyright (C) 1999 Linus Torvalds
6 * Copyright (C) 2002 Christoph Hellwig
7 */
8
9#include <linux/mman.h>
10#include <linux/pagemap.h>
11#include <linux/syscalls.h>
12#include <linux/mempolicy.h>
13#include <linux/page-isolation.h>
14#include <linux/page_idle.h>
15#include <linux/userfaultfd_k.h>
16#include <linux/hugetlb.h>
17#include <linux/falloc.h>
18#include <linux/fadvise.h>
19#include <linux/sched.h>
20#include <linux/ksm.h>
21#include <linux/fs.h>
22#include <linux/file.h>
23#include <linux/blkdev.h>
24#include <linux/backing-dev.h>
25#include <linux/pagewalk.h>
26#include <linux/swap.h>
27#include <linux/swapops.h>
28#include <linux/shmem_fs.h>
29#include <linux/mmu_notifier.h>
30
31#include <asm/tlb.h>
32
33#include "internal.h"
34
35struct madvise_walk_private {
36 struct mmu_gather *tlb;
37 bool pageout;
38};
39
40/*
41 * Any behaviour which results in changes to the vma->vm_flags needs to
42 * take mmap_sem for writing. Others, which simply traverse vmas, need
43 * to only take it for reading.
44 */
45static int madvise_need_mmap_write(int behavior)
46{
47 switch (behavior) {
48 case MADV_REMOVE:
49 case MADV_WILLNEED:
50 case MADV_DONTNEED:
51 case MADV_COLD:
52 case MADV_PAGEOUT:
53 case MADV_FREE:
54 return 0;
55 default:
56 /* be safe, default to 1. list exceptions explicitly */
57 return 1;
58 }
59}
60
61/*
62 * We can potentially split a vm area into separate
63 * areas, each area with its own behavior.
64 */
65static long madvise_behavior(struct vm_area_struct *vma,
66 struct vm_area_struct **prev,
67 unsigned long start, unsigned long end, int behavior)
68{
69 struct mm_struct *mm = vma->vm_mm;
70 int error = 0;
71 pgoff_t pgoff;
72 unsigned long new_flags = vma->vm_flags;
73
74 switch (behavior) {
75 case MADV_NORMAL:
76 new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
77 break;
78 case MADV_SEQUENTIAL:
79 new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
80 break;
81 case MADV_RANDOM:
82 new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
83 break;
84 case MADV_DONTFORK:
85 new_flags |= VM_DONTCOPY;
86 break;
87 case MADV_DOFORK:
88 if (vma->vm_flags & VM_IO) {
89 error = -EINVAL;
90 goto out;
91 }
92 new_flags &= ~VM_DONTCOPY;
93 break;
94 case MADV_WIPEONFORK:
95 /* MADV_WIPEONFORK is only supported on anonymous memory. */
96 if (vma->vm_file || vma->vm_flags & VM_SHARED) {
97 error = -EINVAL;
98 goto out;
99 }
100 new_flags |= VM_WIPEONFORK;
101 break;
102 case MADV_KEEPONFORK:
103 new_flags &= ~VM_WIPEONFORK;
104 break;
105 case MADV_DONTDUMP:
106 new_flags |= VM_DONTDUMP;
107 break;
108 case MADV_DODUMP:
109 if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL) {
110 error = -EINVAL;
111 goto out;
112 }
113 new_flags &= ~VM_DONTDUMP;
114 break;
115 case MADV_MERGEABLE:
116 case MADV_UNMERGEABLE:
117 error = ksm_madvise(vma, start, end, behavior, &new_flags);
118 if (error)
119 goto out_convert_errno;
120 break;
121 case MADV_HUGEPAGE:
122 case MADV_NOHUGEPAGE:
123 error = hugepage_madvise(vma, &new_flags, behavior);
124 if (error)
125 goto out_convert_errno;
126 break;
127 }
128
129 if (new_flags == vma->vm_flags) {
130 *prev = vma;
131 goto out;
132 }
133
134 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
135 *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
136 vma->vm_file, pgoff, vma_policy(vma),
137 vma->vm_userfaultfd_ctx);
138 if (*prev) {
139 vma = *prev;
140 goto success;
141 }
142
143 *prev = vma;
144
145 if (start != vma->vm_start) {
146 if (unlikely(mm->map_count >= sysctl_max_map_count)) {
147 error = -ENOMEM;
148 goto out;
149 }
150 error = __split_vma(mm, vma, start, 1);
151 if (error)
152 goto out_convert_errno;
153 }
154
155 if (end != vma->vm_end) {
156 if (unlikely(mm->map_count >= sysctl_max_map_count)) {
157 error = -ENOMEM;
158 goto out;
159 }
160 error = __split_vma(mm, vma, end, 0);
161 if (error)
162 goto out_convert_errno;
163 }
164
165success:
166 /*
167 * vm_flags is protected by the mmap_sem held in write mode.
168 */
169 vma->vm_flags = new_flags;
170
171out_convert_errno:
172 /*
173 * madvise() returns EAGAIN if kernel resources, such as
174 * slab, are temporarily unavailable.
175 */
176 if (error == -ENOMEM)
177 error = -EAGAIN;
178out:
179 return error;
180}
181
182#ifdef CONFIG_SWAP
183static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
184 unsigned long end, struct mm_walk *walk)
185{
186 pte_t *orig_pte;
187 struct vm_area_struct *vma = walk->private;
188 unsigned long index;
189
190 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
191 return 0;
192
193 for (index = start; index != end; index += PAGE_SIZE) {
194 pte_t pte;
195 swp_entry_t entry;
196 struct page *page;
197 spinlock_t *ptl;
198
199 orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
200 pte = *(orig_pte + ((index - start) / PAGE_SIZE));
201 pte_unmap_unlock(orig_pte, ptl);
202
203 if (pte_present(pte) || pte_none(pte))
204 continue;
205 entry = pte_to_swp_entry(pte);
206 if (unlikely(non_swap_entry(entry)))
207 continue;
208
209 page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
210 vma, index, false);
211 if (page)
212 put_page(page);
213 }
214
215 return 0;
216}
217
218static const struct mm_walk_ops swapin_walk_ops = {
219 .pmd_entry = swapin_walk_pmd_entry,
220};
221
222static void force_shm_swapin_readahead(struct vm_area_struct *vma,
223 unsigned long start, unsigned long end,
224 struct address_space *mapping)
225{
226 pgoff_t index;
227 struct page *page;
228 swp_entry_t swap;
229
230 for (; start < end; start += PAGE_SIZE) {
231 index = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
232
233 page = find_get_entry(mapping, index);
234 if (!xa_is_value(page)) {
235 if (page)
236 put_page(page);
237 continue;
238 }
239 swap = radix_to_swp_entry(page);
240 page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE,
241 NULL, 0, false);
242 if (page)
243 put_page(page);
244 }
245
246 lru_add_drain(); /* Push any new pages onto the LRU now */
247}
248#endif /* CONFIG_SWAP */
249
250/*
251 * Schedule all required I/O operations. Do not wait for completion.
252 */
253static long madvise_willneed(struct vm_area_struct *vma,
254 struct vm_area_struct **prev,
255 unsigned long start, unsigned long end)
256{
257 struct file *file = vma->vm_file;
258 loff_t offset;
259
260 *prev = vma;
261#ifdef CONFIG_SWAP
262 if (!file) {
263 walk_page_range(vma->vm_mm, start, end, &swapin_walk_ops, vma);
264 lru_add_drain(); /* Push any new pages onto the LRU now */
265 return 0;
266 }
267
268 if (shmem_mapping(file->f_mapping)) {
269 force_shm_swapin_readahead(vma, start, end,
270 file->f_mapping);
271 return 0;
272 }
273#else
274 if (!file)
275 return -EBADF;
276#endif
277
278 if (IS_DAX(file_inode(file))) {
279 /* no bad return value, but ignore advice */
280 return 0;
281 }
282
283 /*
284 * Filesystem's fadvise may need to take various locks. We need to
285 * explicitly grab a reference because the vma (and hence the
286 * vma's reference to the file) can go away as soon as we drop
287 * mmap_sem.
288 */
289 *prev = NULL; /* tell sys_madvise we drop mmap_sem */
290 get_file(file);
291 up_read(¤t->mm->mmap_sem);
292 offset = (loff_t)(start - vma->vm_start)
293 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
294 vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED);
295 fput(file);
296 down_read(¤t->mm->mmap_sem);
297 return 0;
298}
299
300static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
301 unsigned long addr, unsigned long end,
302 struct mm_walk *walk)
303{
304 struct madvise_walk_private *private = walk->private;
305 struct mmu_gather *tlb = private->tlb;
306 bool pageout = private->pageout;
307 struct mm_struct *mm = tlb->mm;
308 struct vm_area_struct *vma = walk->vma;
309 pte_t *orig_pte, *pte, ptent;
310 spinlock_t *ptl;
311 struct page *page = NULL;
312 LIST_HEAD(page_list);
313
314 if (fatal_signal_pending(current))
315 return -EINTR;
316
317#ifdef CONFIG_TRANSPARENT_HUGEPAGE
318 if (pmd_trans_huge(*pmd)) {
319 pmd_t orig_pmd;
320 unsigned long next = pmd_addr_end(addr, end);
321
322 tlb_change_page_size(tlb, HPAGE_PMD_SIZE);
323 ptl = pmd_trans_huge_lock(pmd, vma);
324 if (!ptl)
325 return 0;
326
327 orig_pmd = *pmd;
328 if (is_huge_zero_pmd(orig_pmd))
329 goto huge_unlock;
330
331 if (unlikely(!pmd_present(orig_pmd))) {
332 VM_BUG_ON(thp_migration_supported() &&
333 !is_pmd_migration_entry(orig_pmd));
334 goto huge_unlock;
335 }
336
337 page = pmd_page(orig_pmd);
338 if (next - addr != HPAGE_PMD_SIZE) {
339 int err;
340
341 if (page_mapcount(page) != 1)
342 goto huge_unlock;
343
344 get_page(page);
345 spin_unlock(ptl);
346 lock_page(page);
347 err = split_huge_page(page);
348 unlock_page(page);
349 put_page(page);
350 if (!err)
351 goto regular_page;
352 return 0;
353 }
354
355 if (pmd_young(orig_pmd)) {
356 pmdp_invalidate(vma, addr, pmd);
357 orig_pmd = pmd_mkold(orig_pmd);
358
359 set_pmd_at(mm, addr, pmd, orig_pmd);
360 tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
361 }
362
363 ClearPageReferenced(page);
364 test_and_clear_page_young(page);
365 if (pageout) {
366 if (!isolate_lru_page(page)) {
367 if (PageUnevictable(page))
368 putback_lru_page(page);
369 else
370 list_add(&page->lru, &page_list);
371 }
372 } else
373 deactivate_page(page);
374huge_unlock:
375 spin_unlock(ptl);
376 if (pageout)
377 reclaim_pages(&page_list);
378 return 0;
379 }
380
381 if (pmd_trans_unstable(pmd))
382 return 0;
383regular_page:
384#endif
385 tlb_change_page_size(tlb, PAGE_SIZE);
386 orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
387 flush_tlb_batched_pending(mm);
388 arch_enter_lazy_mmu_mode();
389 for (; addr < end; pte++, addr += PAGE_SIZE) {
390 ptent = *pte;
391
392 if (pte_none(ptent))
393 continue;
394
395 if (!pte_present(ptent))
396 continue;
397
398 page = vm_normal_page(vma, addr, ptent);
399 if (!page)
400 continue;
401
402 /*
403 * Creating a THP page is expensive so split it only if we
404 * are sure it's worth. Split it if we are only owner.
405 */
406 if (PageTransCompound(page)) {
407 if (page_mapcount(page) != 1)
408 break;
409 get_page(page);
410 if (!trylock_page(page)) {
411 put_page(page);
412 break;
413 }
414 pte_unmap_unlock(orig_pte, ptl);
415 if (split_huge_page(page)) {
416 unlock_page(page);
417 put_page(page);
418 pte_offset_map_lock(mm, pmd, addr, &ptl);
419 break;
420 }
421 unlock_page(page);
422 put_page(page);
423 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
424 pte--;
425 addr -= PAGE_SIZE;
426 continue;
427 }
428
429 VM_BUG_ON_PAGE(PageTransCompound(page), page);
430
431 if (pte_young(ptent)) {
432 ptent = ptep_get_and_clear_full(mm, addr, pte,
433 tlb->fullmm);
434 ptent = pte_mkold(ptent);
435 set_pte_at(mm, addr, pte, ptent);
436 tlb_remove_tlb_entry(tlb, pte, addr);
437 }
438
439 /*
440 * We are deactivating a page for accelerating reclaiming.
441 * VM couldn't reclaim the page unless we clear PG_young.
442 * As a side effect, it makes confuse idle-page tracking
443 * because they will miss recent referenced history.
444 */
445 ClearPageReferenced(page);
446 test_and_clear_page_young(page);
447 if (pageout) {
448 if (!isolate_lru_page(page)) {
449 if (PageUnevictable(page))
450 putback_lru_page(page);
451 else
452 list_add(&page->lru, &page_list);
453 }
454 } else
455 deactivate_page(page);
456 }
457
458 arch_leave_lazy_mmu_mode();
459 pte_unmap_unlock(orig_pte, ptl);
460 if (pageout)
461 reclaim_pages(&page_list);
462 cond_resched();
463
464 return 0;
465}
466
467static const struct mm_walk_ops cold_walk_ops = {
468 .pmd_entry = madvise_cold_or_pageout_pte_range,
469};
470
471static void madvise_cold_page_range(struct mmu_gather *tlb,
472 struct vm_area_struct *vma,
473 unsigned long addr, unsigned long end)
474{
475 struct madvise_walk_private walk_private = {
476 .pageout = false,
477 .tlb = tlb,
478 };
479
480 tlb_start_vma(tlb, vma);
481 walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
482 tlb_end_vma(tlb, vma);
483}
484
485static long madvise_cold(struct vm_area_struct *vma,
486 struct vm_area_struct **prev,
487 unsigned long start_addr, unsigned long end_addr)
488{
489 struct mm_struct *mm = vma->vm_mm;
490 struct mmu_gather tlb;
491
492 *prev = vma;
493 if (!can_madv_lru_vma(vma))
494 return -EINVAL;
495
496 lru_add_drain();
497 tlb_gather_mmu(&tlb, mm, start_addr, end_addr);
498 madvise_cold_page_range(&tlb, vma, start_addr, end_addr);
499 tlb_finish_mmu(&tlb, start_addr, end_addr);
500
501 return 0;
502}
503
504static void madvise_pageout_page_range(struct mmu_gather *tlb,
505 struct vm_area_struct *vma,
506 unsigned long addr, unsigned long end)
507{
508 struct madvise_walk_private walk_private = {
509 .pageout = true,
510 .tlb = tlb,
511 };
512
513 tlb_start_vma(tlb, vma);
514 walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
515 tlb_end_vma(tlb, vma);
516}
517
518static inline bool can_do_pageout(struct vm_area_struct *vma)
519{
520 if (vma_is_anonymous(vma))
521 return true;
522 if (!vma->vm_file)
523 return false;
524 /*
525 * paging out pagecache only for non-anonymous mappings that correspond
526 * to the files the calling process could (if tried) open for writing;
527 * otherwise we'd be including shared non-exclusive mappings, which
528 * opens a side channel.
529 */
530 return inode_owner_or_capable(file_inode(vma->vm_file)) ||
531 inode_permission(file_inode(vma->vm_file), MAY_WRITE) == 0;
532}
533
534static long madvise_pageout(struct vm_area_struct *vma,
535 struct vm_area_struct **prev,
536 unsigned long start_addr, unsigned long end_addr)
537{
538 struct mm_struct *mm = vma->vm_mm;
539 struct mmu_gather tlb;
540
541 *prev = vma;
542 if (!can_madv_lru_vma(vma))
543 return -EINVAL;
544
545 if (!can_do_pageout(vma))
546 return 0;
547
548 lru_add_drain();
549 tlb_gather_mmu(&tlb, mm, start_addr, end_addr);
550 madvise_pageout_page_range(&tlb, vma, start_addr, end_addr);
551 tlb_finish_mmu(&tlb, start_addr, end_addr);
552
553 return 0;
554}
555
556static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
557 unsigned long end, struct mm_walk *walk)
558
559{
560 struct mmu_gather *tlb = walk->private;
561 struct mm_struct *mm = tlb->mm;
562 struct vm_area_struct *vma = walk->vma;
563 spinlock_t *ptl;
564 pte_t *orig_pte, *pte, ptent;
565 struct page *page;
566 int nr_swap = 0;
567 unsigned long next;
568
569 next = pmd_addr_end(addr, end);
570 if (pmd_trans_huge(*pmd))
571 if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next))
572 goto next;
573
574 if (pmd_trans_unstable(pmd))
575 return 0;
576
577 tlb_change_page_size(tlb, PAGE_SIZE);
578 orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
579 flush_tlb_batched_pending(mm);
580 arch_enter_lazy_mmu_mode();
581 for (; addr != end; pte++, addr += PAGE_SIZE) {
582 ptent = *pte;
583
584 if (pte_none(ptent))
585 continue;
586 /*
587 * If the pte has swp_entry, just clear page table to
588 * prevent swap-in which is more expensive rather than
589 * (page allocation + zeroing).
590 */
591 if (!pte_present(ptent)) {
592 swp_entry_t entry;
593
594 entry = pte_to_swp_entry(ptent);
595 if (non_swap_entry(entry))
596 continue;
597 nr_swap--;
598 free_swap_and_cache(entry);
599 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
600 continue;
601 }
602
603 page = vm_normal_page(vma, addr, ptent);
604 if (!page)
605 continue;
606
607 /*
608 * If pmd isn't transhuge but the page is THP and
609 * is owned by only this process, split it and
610 * deactivate all pages.
611 */
612 if (PageTransCompound(page)) {
613 if (page_mapcount(page) != 1)
614 goto out;
615 get_page(page);
616 if (!trylock_page(page)) {
617 put_page(page);
618 goto out;
619 }
620 pte_unmap_unlock(orig_pte, ptl);
621 if (split_huge_page(page)) {
622 unlock_page(page);
623 put_page(page);
624 pte_offset_map_lock(mm, pmd, addr, &ptl);
625 goto out;
626 }
627 unlock_page(page);
628 put_page(page);
629 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
630 pte--;
631 addr -= PAGE_SIZE;
632 continue;
633 }
634
635 VM_BUG_ON_PAGE(PageTransCompound(page), page);
636
637 if (PageSwapCache(page) || PageDirty(page)) {
638 if (!trylock_page(page))
639 continue;
640 /*
641 * If page is shared with others, we couldn't clear
642 * PG_dirty of the page.
643 */
644 if (page_mapcount(page) != 1) {
645 unlock_page(page);
646 continue;
647 }
648
649 if (PageSwapCache(page) && !try_to_free_swap(page)) {
650 unlock_page(page);
651 continue;
652 }
653
654 ClearPageDirty(page);
655 unlock_page(page);
656 }
657
658 if (pte_young(ptent) || pte_dirty(ptent)) {
659 /*
660 * Some of architecture(ex, PPC) don't update TLB
661 * with set_pte_at and tlb_remove_tlb_entry so for
662 * the portability, remap the pte with old|clean
663 * after pte clearing.
664 */
665 ptent = ptep_get_and_clear_full(mm, addr, pte,
666 tlb->fullmm);
667
668 ptent = pte_mkold(ptent);
669 ptent = pte_mkclean(ptent);
670 set_pte_at(mm, addr, pte, ptent);
671 tlb_remove_tlb_entry(tlb, pte, addr);
672 }
673 mark_page_lazyfree(page);
674 }
675out:
676 if (nr_swap) {
677 if (current->mm == mm)
678 sync_mm_rss(mm);
679
680 add_mm_counter(mm, MM_SWAPENTS, nr_swap);
681 }
682 arch_leave_lazy_mmu_mode();
683 pte_unmap_unlock(orig_pte, ptl);
684 cond_resched();
685next:
686 return 0;
687}
688
689static const struct mm_walk_ops madvise_free_walk_ops = {
690 .pmd_entry = madvise_free_pte_range,
691};
692
693static int madvise_free_single_vma(struct vm_area_struct *vma,
694 unsigned long start_addr, unsigned long end_addr)
695{
696 struct mm_struct *mm = vma->vm_mm;
697 struct mmu_notifier_range range;
698 struct mmu_gather tlb;
699
700 /* MADV_FREE works for only anon vma at the moment */
701 if (!vma_is_anonymous(vma))
702 return -EINVAL;
703
704 range.start = max(vma->vm_start, start_addr);
705 if (range.start >= vma->vm_end)
706 return -EINVAL;
707 range.end = min(vma->vm_end, end_addr);
708 if (range.end <= vma->vm_start)
709 return -EINVAL;
710 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm,
711 range.start, range.end);
712
713 lru_add_drain();
714 tlb_gather_mmu(&tlb, mm, range.start, range.end);
715 update_hiwater_rss(mm);
716
717 mmu_notifier_invalidate_range_start(&range);
718 tlb_start_vma(&tlb, vma);
719 walk_page_range(vma->vm_mm, range.start, range.end,
720 &madvise_free_walk_ops, &tlb);
721 tlb_end_vma(&tlb, vma);
722 mmu_notifier_invalidate_range_end(&range);
723 tlb_finish_mmu(&tlb, range.start, range.end);
724
725 return 0;
726}
727
728/*
729 * Application no longer needs these pages. If the pages are dirty,
730 * it's OK to just throw them away. The app will be more careful about
731 * data it wants to keep. Be sure to free swap resources too. The
732 * zap_page_range call sets things up for shrink_active_list to actually free
733 * these pages later if no one else has touched them in the meantime,
734 * although we could add these pages to a global reuse list for
735 * shrink_active_list to pick up before reclaiming other pages.
736 *
737 * NB: This interface discards data rather than pushes it out to swap,
738 * as some implementations do. This has performance implications for
739 * applications like large transactional databases which want to discard
740 * pages in anonymous maps after committing to backing store the data
741 * that was kept in them. There is no reason to write this data out to
742 * the swap area if the application is discarding it.
743 *
744 * An interface that causes the system to free clean pages and flush
745 * dirty pages is already available as msync(MS_INVALIDATE).
746 */
747static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
748 unsigned long start, unsigned long end)
749{
750 zap_page_range(vma, start, end - start);
751 return 0;
752}
753
754static long madvise_dontneed_free(struct vm_area_struct *vma,
755 struct vm_area_struct **prev,
756 unsigned long start, unsigned long end,
757 int behavior)
758{
759 *prev = vma;
760 if (!can_madv_lru_vma(vma))
761 return -EINVAL;
762
763 if (!userfaultfd_remove(vma, start, end)) {
764 *prev = NULL; /* mmap_sem has been dropped, prev is stale */
765
766 down_read(¤t->mm->mmap_sem);
767 vma = find_vma(current->mm, start);
768 if (!vma)
769 return -ENOMEM;
770 if (start < vma->vm_start) {
771 /*
772 * This "vma" under revalidation is the one
773 * with the lowest vma->vm_start where start
774 * is also < vma->vm_end. If start <
775 * vma->vm_start it means an hole materialized
776 * in the user address space within the
777 * virtual range passed to MADV_DONTNEED
778 * or MADV_FREE.
779 */
780 return -ENOMEM;
781 }
782 if (!can_madv_lru_vma(vma))
783 return -EINVAL;
784 if (end > vma->vm_end) {
785 /*
786 * Don't fail if end > vma->vm_end. If the old
787 * vma was splitted while the mmap_sem was
788 * released the effect of the concurrent
789 * operation may not cause madvise() to
790 * have an undefined result. There may be an
791 * adjacent next vma that we'll walk
792 * next. userfaultfd_remove() will generate an
793 * UFFD_EVENT_REMOVE repetition on the
794 * end-vma->vm_end range, but the manager can
795 * handle a repetition fine.
796 */
797 end = vma->vm_end;
798 }
799 VM_WARN_ON(start >= end);
800 }
801
802 if (behavior == MADV_DONTNEED)
803 return madvise_dontneed_single_vma(vma, start, end);
804 else if (behavior == MADV_FREE)
805 return madvise_free_single_vma(vma, start, end);
806 else
807 return -EINVAL;
808}
809
810/*
811 * Application wants to free up the pages and associated backing store.
812 * This is effectively punching a hole into the middle of a file.
813 */
814static long madvise_remove(struct vm_area_struct *vma,
815 struct vm_area_struct **prev,
816 unsigned long start, unsigned long end)
817{
818 loff_t offset;
819 int error;
820 struct file *f;
821
822 *prev = NULL; /* tell sys_madvise we drop mmap_sem */
823
824 if (vma->vm_flags & VM_LOCKED)
825 return -EINVAL;
826
827 f = vma->vm_file;
828
829 if (!f || !f->f_mapping || !f->f_mapping->host) {
830 return -EINVAL;
831 }
832
833 if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
834 return -EACCES;
835
836 offset = (loff_t)(start - vma->vm_start)
837 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
838
839 /*
840 * Filesystem's fallocate may need to take i_mutex. We need to
841 * explicitly grab a reference because the vma (and hence the
842 * vma's reference to the file) can go away as soon as we drop
843 * mmap_sem.
844 */
845 get_file(f);
846 if (userfaultfd_remove(vma, start, end)) {
847 /* mmap_sem was not released by userfaultfd_remove() */
848 up_read(¤t->mm->mmap_sem);
849 }
850 error = vfs_fallocate(f,
851 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
852 offset, end - start);
853 fput(f);
854 down_read(¤t->mm->mmap_sem);
855 return error;
856}
857
858#ifdef CONFIG_MEMORY_FAILURE
859/*
860 * Error injection support for memory error handling.
861 */
862static int madvise_inject_error(int behavior,
863 unsigned long start, unsigned long end)
864{
865 struct page *page;
866 struct zone *zone;
867 unsigned int order;
868
869 if (!capable(CAP_SYS_ADMIN))
870 return -EPERM;
871
872
873 for (; start < end; start += PAGE_SIZE << order) {
874 unsigned long pfn;
875 int ret;
876
877 ret = get_user_pages_fast(start, 1, 0, &page);
878 if (ret != 1)
879 return ret;
880 pfn = page_to_pfn(page);
881
882 /*
883 * When soft offlining hugepages, after migrating the page
884 * we dissolve it, therefore in the second loop "page" will
885 * no longer be a compound page, and order will be 0.
886 */
887 order = compound_order(compound_head(page));
888
889 if (PageHWPoison(page)) {
890 put_page(page);
891 continue;
892 }
893
894 if (behavior == MADV_SOFT_OFFLINE) {
895 pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
896 pfn, start);
897
898 ret = soft_offline_page(page, MF_COUNT_INCREASED);
899 if (ret)
900 return ret;
901 continue;
902 }
903
904 pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
905 pfn, start);
906
907 /*
908 * Drop the page reference taken by get_user_pages_fast(). In
909 * the absence of MF_COUNT_INCREASED the memory_failure()
910 * routine is responsible for pinning the page to prevent it
911 * from being released back to the page allocator.
912 */
913 put_page(page);
914 ret = memory_failure(pfn, 0);
915 if (ret)
916 return ret;
917 }
918
919 /* Ensure that all poisoned pages are removed from per-cpu lists */
920 for_each_populated_zone(zone)
921 drain_all_pages(zone);
922
923 return 0;
924}
925#endif
926
927static long
928madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
929 unsigned long start, unsigned long end, int behavior)
930{
931 switch (behavior) {
932 case MADV_REMOVE:
933 return madvise_remove(vma, prev, start, end);
934 case MADV_WILLNEED:
935 return madvise_willneed(vma, prev, start, end);
936 case MADV_COLD:
937 return madvise_cold(vma, prev, start, end);
938 case MADV_PAGEOUT:
939 return madvise_pageout(vma, prev, start, end);
940 case MADV_FREE:
941 case MADV_DONTNEED:
942 return madvise_dontneed_free(vma, prev, start, end, behavior);
943 default:
944 return madvise_behavior(vma, prev, start, end, behavior);
945 }
946}
947
948static bool
949madvise_behavior_valid(int behavior)
950{
951 switch (behavior) {
952 case MADV_DOFORK:
953 case MADV_DONTFORK:
954 case MADV_NORMAL:
955 case MADV_SEQUENTIAL:
956 case MADV_RANDOM:
957 case MADV_REMOVE:
958 case MADV_WILLNEED:
959 case MADV_DONTNEED:
960 case MADV_FREE:
961 case MADV_COLD:
962 case MADV_PAGEOUT:
963#ifdef CONFIG_KSM
964 case MADV_MERGEABLE:
965 case MADV_UNMERGEABLE:
966#endif
967#ifdef CONFIG_TRANSPARENT_HUGEPAGE
968 case MADV_HUGEPAGE:
969 case MADV_NOHUGEPAGE:
970#endif
971 case MADV_DONTDUMP:
972 case MADV_DODUMP:
973 case MADV_WIPEONFORK:
974 case MADV_KEEPONFORK:
975#ifdef CONFIG_MEMORY_FAILURE
976 case MADV_SOFT_OFFLINE:
977 case MADV_HWPOISON:
978#endif
979 return true;
980
981 default:
982 return false;
983 }
984}
985
986/*
987 * The madvise(2) system call.
988 *
989 * Applications can use madvise() to advise the kernel how it should
990 * handle paging I/O in this VM area. The idea is to help the kernel
991 * use appropriate read-ahead and caching techniques. The information
992 * provided is advisory only, and can be safely disregarded by the
993 * kernel without affecting the correct operation of the application.
994 *
995 * behavior values:
996 * MADV_NORMAL - the default behavior is to read clusters. This
997 * results in some read-ahead and read-behind.
998 * MADV_RANDOM - the system should read the minimum amount of data
999 * on any access, since it is unlikely that the appli-
1000 * cation will need more than what it asks for.
1001 * MADV_SEQUENTIAL - pages in the given range will probably be accessed
1002 * once, so they can be aggressively read ahead, and
1003 * can be freed soon after they are accessed.
1004 * MADV_WILLNEED - the application is notifying the system to read
1005 * some pages ahead.
1006 * MADV_DONTNEED - the application is finished with the given range,
1007 * so the kernel can free resources associated with it.
1008 * MADV_FREE - the application marks pages in the given range as lazy free,
1009 * where actual purges are postponed until memory pressure happens.
1010 * MADV_REMOVE - the application wants to free up the given range of
1011 * pages and associated backing store.
1012 * MADV_DONTFORK - omit this area from child's address space when forking:
1013 * typically, to avoid COWing pages pinned by get_user_pages().
1014 * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
1015 * MADV_WIPEONFORK - present the child process with zero-filled memory in this
1016 * range after a fork.
1017 * MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
1018 * MADV_HWPOISON - trigger memory error handler as if the given memory range
1019 * were corrupted by unrecoverable hardware memory failure.
1020 * MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
1021 * MADV_MERGEABLE - the application recommends that KSM try to merge pages in
1022 * this area with pages of identical content from other such areas.
1023 * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
1024 * MADV_HUGEPAGE - the application wants to back the given range by transparent
1025 * huge pages in the future. Existing pages might be coalesced and
1026 * new pages might be allocated as THP.
1027 * MADV_NOHUGEPAGE - mark the given range as not worth being backed by
1028 * transparent huge pages so the existing pages will not be
1029 * coalesced into THP and new pages will not be allocated as THP.
1030 * MADV_DONTDUMP - the application wants to prevent pages in the given range
1031 * from being included in its core dump.
1032 * MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
1033 *
1034 * return values:
1035 * zero - success
1036 * -EINVAL - start + len < 0, start is not page-aligned,
1037 * "behavior" is not a valid value, or application
1038 * is attempting to release locked or shared pages,
1039 * or the specified address range includes file, Huge TLB,
1040 * MAP_SHARED or VMPFNMAP range.
1041 * -ENOMEM - addresses in the specified range are not currently
1042 * mapped, or are outside the AS of the process.
1043 * -EIO - an I/O error occurred while paging in data.
1044 * -EBADF - map exists, but area maps something that isn't a file.
1045 * -EAGAIN - a kernel resource was temporarily unavailable.
1046 */
1047SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
1048{
1049 unsigned long end, tmp;
1050 struct vm_area_struct *vma, *prev;
1051 int unmapped_error = 0;
1052 int error = -EINVAL;
1053 int write;
1054 size_t len;
1055 struct blk_plug plug;
1056
1057 start = untagged_addr(start);
1058
1059 if (!madvise_behavior_valid(behavior))
1060 return error;
1061
1062 if (start & ~PAGE_MASK)
1063 return error;
1064 len = (len_in + ~PAGE_MASK) & PAGE_MASK;
1065
1066 /* Check to see whether len was rounded up from small -ve to zero */
1067 if (len_in && !len)
1068 return error;
1069
1070 end = start + len;
1071 if (end < start)
1072 return error;
1073
1074 error = 0;
1075 if (end == start)
1076 return error;
1077
1078#ifdef CONFIG_MEMORY_FAILURE
1079 if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
1080 return madvise_inject_error(behavior, start, start + len_in);
1081#endif
1082
1083 write = madvise_need_mmap_write(behavior);
1084 if (write) {
1085 if (down_write_killable(¤t->mm->mmap_sem))
1086 return -EINTR;
1087 } else {
1088 down_read(¤t->mm->mmap_sem);
1089 }
1090
1091 /*
1092 * If the interval [start,end) covers some unmapped address
1093 * ranges, just ignore them, but return -ENOMEM at the end.
1094 * - different from the way of handling in mlock etc.
1095 */
1096 vma = find_vma_prev(current->mm, start, &prev);
1097 if (vma && start > vma->vm_start)
1098 prev = vma;
1099
1100 blk_start_plug(&plug);
1101 for (;;) {
1102 /* Still start < end. */
1103 error = -ENOMEM;
1104 if (!vma)
1105 goto out;
1106
1107 /* Here start < (end|vma->vm_end). */
1108 if (start < vma->vm_start) {
1109 unmapped_error = -ENOMEM;
1110 start = vma->vm_start;
1111 if (start >= end)
1112 goto out;
1113 }
1114
1115 /* Here vma->vm_start <= start < (end|vma->vm_end) */
1116 tmp = vma->vm_end;
1117 if (end < tmp)
1118 tmp = end;
1119
1120 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
1121 error = madvise_vma(vma, &prev, start, tmp, behavior);
1122 if (error)
1123 goto out;
1124 start = tmp;
1125 if (prev && start < prev->vm_end)
1126 start = prev->vm_end;
1127 error = unmapped_error;
1128 if (start >= end)
1129 goto out;
1130 if (prev)
1131 vma = prev->vm_next;
1132 else /* madvise_remove dropped mmap_sem */
1133 vma = find_vma(current->mm, start);
1134 }
1135out:
1136 blk_finish_plug(&plug);
1137 if (write)
1138 up_write(¤t->mm->mmap_sem);
1139 else
1140 up_read(¤t->mm->mmap_sem);
1141
1142 return error;
1143}