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