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