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1 // SPDX-License-Identifier: GPL-2.0
5 * Copyright (C) 1999 Linus Torvalds
6 * Copyright (C) 2002 Christoph Hellwig
9 #include <linux/mman.h>
10 #include <linux/pagemap.h>
11 #include <linux/syscalls.h>
12 #include <linux/mempolicy.h>
13 #include <linux/page-isolation.h>
14 #include <linux/userfaultfd_k.h>
15 #include <linux/hugetlb.h>
16 #include <linux/falloc.h>
17 #include <linux/sched.h>
18 #include <linux/ksm.h>
20 #include <linux/file.h>
21 #include <linux/blkdev.h>
22 #include <linux/backing-dev.h>
23 #include <linux/swap.h>
24 #include <linux/swapops.h>
25 #include <linux/shmem_fs.h>
26 #include <linux/mmu_notifier.h>
33 * Any behaviour which results in changes to the vma->vm_flags needs to
34 * take mmap_sem for writing. Others, which simply traverse vmas, need
35 * to only take it for reading.
37 static int madvise_need_mmap_write(int behavior
)
46 /* be safe, default to 1. list exceptions explicitly */
52 * We can potentially split a vm area into separate
53 * areas, each area with its own behavior.
55 static long madvise_behavior(struct vm_area_struct
*vma
,
56 struct vm_area_struct
**prev
,
57 unsigned long start
, unsigned long end
, int behavior
)
59 struct mm_struct
*mm
= vma
->vm_mm
;
62 unsigned long new_flags
= vma
->vm_flags
;
66 new_flags
= new_flags
& ~VM_RAND_READ
& ~VM_SEQ_READ
;
69 new_flags
= (new_flags
& ~VM_RAND_READ
) | VM_SEQ_READ
;
72 new_flags
= (new_flags
& ~VM_SEQ_READ
) | VM_RAND_READ
;
75 new_flags
|= VM_DONTCOPY
;
78 if (vma
->vm_flags
& VM_IO
) {
82 new_flags
&= ~VM_DONTCOPY
;
85 /* MADV_WIPEONFORK is only supported on anonymous memory. */
86 if (vma
->vm_file
|| vma
->vm_flags
& VM_SHARED
) {
90 new_flags
|= VM_WIPEONFORK
;
93 new_flags
&= ~VM_WIPEONFORK
;
96 new_flags
|= VM_DONTDUMP
;
99 if (new_flags
& VM_SPECIAL
) {
103 new_flags
&= ~VM_DONTDUMP
;
106 case MADV_UNMERGEABLE
:
107 error
= ksm_madvise(vma
, start
, end
, behavior
, &new_flags
);
110 * madvise() returns EAGAIN if kernel resources, such as
111 * slab, are temporarily unavailable.
113 if (error
== -ENOMEM
)
119 case MADV_NOHUGEPAGE
:
120 error
= hugepage_madvise(vma
, &new_flags
, behavior
);
123 * madvise() returns EAGAIN if kernel resources, such as
124 * slab, are temporarily unavailable.
126 if (error
== -ENOMEM
)
133 if (new_flags
== vma
->vm_flags
) {
138 pgoff
= vma
->vm_pgoff
+ ((start
- vma
->vm_start
) >> PAGE_SHIFT
);
139 *prev
= vma_merge(mm
, *prev
, start
, end
, new_flags
, vma
->anon_vma
,
140 vma
->vm_file
, pgoff
, vma_policy(vma
),
141 vma
->vm_userfaultfd_ctx
);
149 if (start
!= vma
->vm_start
) {
150 if (unlikely(mm
->map_count
>= sysctl_max_map_count
)) {
154 error
= __split_vma(mm
, vma
, start
, 1);
157 * madvise() returns EAGAIN if kernel resources, such as
158 * slab, are temporarily unavailable.
160 if (error
== -ENOMEM
)
166 if (end
!= vma
->vm_end
) {
167 if (unlikely(mm
->map_count
>= sysctl_max_map_count
)) {
171 error
= __split_vma(mm
, vma
, end
, 0);
174 * madvise() returns EAGAIN if kernel resources, such as
175 * slab, are temporarily unavailable.
177 if (error
== -ENOMEM
)
185 * vm_flags is protected by the mmap_sem held in write mode.
187 vma
->vm_flags
= new_flags
;
193 static int swapin_walk_pmd_entry(pmd_t
*pmd
, unsigned long start
,
194 unsigned long end
, struct mm_walk
*walk
)
197 struct vm_area_struct
*vma
= walk
->private;
200 if (pmd_none_or_trans_huge_or_clear_bad(pmd
))
203 for (index
= start
; index
!= end
; index
+= PAGE_SIZE
) {
209 orig_pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, start
, &ptl
);
210 pte
= *(orig_pte
+ ((index
- start
) / PAGE_SIZE
));
211 pte_unmap_unlock(orig_pte
, ptl
);
213 if (pte_present(pte
) || pte_none(pte
))
215 entry
= pte_to_swp_entry(pte
);
216 if (unlikely(non_swap_entry(entry
)))
219 page
= read_swap_cache_async(entry
, GFP_HIGHUSER_MOVABLE
,
228 static void force_swapin_readahead(struct vm_area_struct
*vma
,
229 unsigned long start
, unsigned long end
)
231 struct mm_walk walk
= {
233 .pmd_entry
= swapin_walk_pmd_entry
,
237 walk_page_range(start
, end
, &walk
);
239 lru_add_drain(); /* Push any new pages onto the LRU now */
242 static void force_shm_swapin_readahead(struct vm_area_struct
*vma
,
243 unsigned long start
, unsigned long end
,
244 struct address_space
*mapping
)
250 for (; start
< end
; start
+= PAGE_SIZE
) {
251 index
= ((start
- vma
->vm_start
) >> PAGE_SHIFT
) + vma
->vm_pgoff
;
253 page
= find_get_entry(mapping
, index
);
254 if (!radix_tree_exceptional_entry(page
)) {
259 swap
= radix_to_swp_entry(page
);
260 page
= read_swap_cache_async(swap
, GFP_HIGHUSER_MOVABLE
,
266 lru_add_drain(); /* Push any new pages onto the LRU now */
268 #endif /* CONFIG_SWAP */
271 * Schedule all required I/O operations. Do not wait for completion.
273 static long madvise_willneed(struct vm_area_struct
*vma
,
274 struct vm_area_struct
**prev
,
275 unsigned long start
, unsigned long end
)
277 struct file
*file
= vma
->vm_file
;
282 force_swapin_readahead(vma
, start
, end
);
286 if (shmem_mapping(file
->f_mapping
)) {
287 force_shm_swapin_readahead(vma
, start
, end
,
296 if (IS_DAX(file_inode(file
))) {
297 /* no bad return value, but ignore advice */
301 start
= ((start
- vma
->vm_start
) >> PAGE_SHIFT
) + vma
->vm_pgoff
;
302 if (end
> vma
->vm_end
)
304 end
= ((end
- vma
->vm_start
) >> PAGE_SHIFT
) + vma
->vm_pgoff
;
306 force_page_cache_readahead(file
->f_mapping
, file
, start
, end
- start
);
310 static int madvise_free_pte_range(pmd_t
*pmd
, unsigned long addr
,
311 unsigned long end
, struct mm_walk
*walk
)
314 struct mmu_gather
*tlb
= walk
->private;
315 struct mm_struct
*mm
= tlb
->mm
;
316 struct vm_area_struct
*vma
= walk
->vma
;
318 pte_t
*orig_pte
, *pte
, ptent
;
323 next
= pmd_addr_end(addr
, end
);
324 if (pmd_trans_huge(*pmd
))
325 if (madvise_free_huge_pmd(tlb
, vma
, pmd
, addr
, next
))
328 if (pmd_trans_unstable(pmd
))
331 tlb_remove_check_page_size_change(tlb
, PAGE_SIZE
);
332 orig_pte
= pte
= pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
333 flush_tlb_batched_pending(mm
);
334 arch_enter_lazy_mmu_mode();
335 for (; addr
!= end
; pte
++, addr
+= PAGE_SIZE
) {
341 * If the pte has swp_entry, just clear page table to
342 * prevent swap-in which is more expensive rather than
343 * (page allocation + zeroing).
345 if (!pte_present(ptent
)) {
348 entry
= pte_to_swp_entry(ptent
);
349 if (non_swap_entry(entry
))
352 free_swap_and_cache(entry
);
353 pte_clear_not_present_full(mm
, addr
, pte
, tlb
->fullmm
);
357 page
= _vm_normal_page(vma
, addr
, ptent
, true);
362 * If pmd isn't transhuge but the page is THP and
363 * is owned by only this process, split it and
364 * deactivate all pages.
366 if (PageTransCompound(page
)) {
367 if (page_mapcount(page
) != 1)
370 if (!trylock_page(page
)) {
374 pte_unmap_unlock(orig_pte
, ptl
);
375 if (split_huge_page(page
)) {
378 pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
383 pte
= pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
389 VM_BUG_ON_PAGE(PageTransCompound(page
), page
);
391 if (PageSwapCache(page
) || PageDirty(page
)) {
392 if (!trylock_page(page
))
395 * If page is shared with others, we couldn't clear
396 * PG_dirty of the page.
398 if (page_mapcount(page
) != 1) {
403 if (PageSwapCache(page
) && !try_to_free_swap(page
)) {
408 ClearPageDirty(page
);
412 if (pte_young(ptent
) || pte_dirty(ptent
)) {
414 * Some of architecture(ex, PPC) don't update TLB
415 * with set_pte_at and tlb_remove_tlb_entry so for
416 * the portability, remap the pte with old|clean
417 * after pte clearing.
419 ptent
= ptep_get_and_clear_full(mm
, addr
, pte
,
422 ptent
= pte_mkold(ptent
);
423 ptent
= pte_mkclean(ptent
);
424 set_pte_at(mm
, addr
, pte
, ptent
);
425 tlb_remove_tlb_entry(tlb
, pte
, addr
);
427 mark_page_lazyfree(page
);
431 if (current
->mm
== mm
)
434 add_mm_counter(mm
, MM_SWAPENTS
, nr_swap
);
436 arch_leave_lazy_mmu_mode();
437 pte_unmap_unlock(orig_pte
, ptl
);
443 static void madvise_free_page_range(struct mmu_gather
*tlb
,
444 struct vm_area_struct
*vma
,
445 unsigned long addr
, unsigned long end
)
447 struct mm_walk free_walk
= {
448 .pmd_entry
= madvise_free_pte_range
,
453 tlb_start_vma(tlb
, vma
);
454 walk_page_range(addr
, end
, &free_walk
);
455 tlb_end_vma(tlb
, vma
);
458 static int madvise_free_single_vma(struct vm_area_struct
*vma
,
459 unsigned long start_addr
, unsigned long end_addr
)
461 unsigned long start
, end
;
462 struct mm_struct
*mm
= vma
->vm_mm
;
463 struct mmu_gather tlb
;
465 /* MADV_FREE works for only anon vma at the moment */
466 if (!vma_is_anonymous(vma
))
469 start
= max(vma
->vm_start
, start_addr
);
470 if (start
>= vma
->vm_end
)
472 end
= min(vma
->vm_end
, end_addr
);
473 if (end
<= vma
->vm_start
)
477 tlb_gather_mmu(&tlb
, mm
, start
, end
);
478 update_hiwater_rss(mm
);
480 mmu_notifier_invalidate_range_start(mm
, start
, end
);
481 madvise_free_page_range(&tlb
, vma
, start
, end
);
482 mmu_notifier_invalidate_range_end(mm
, start
, end
);
483 tlb_finish_mmu(&tlb
, start
, end
);
489 * Application no longer needs these pages. If the pages are dirty,
490 * it's OK to just throw them away. The app will be more careful about
491 * data it wants to keep. Be sure to free swap resources too. The
492 * zap_page_range call sets things up for shrink_active_list to actually free
493 * these pages later if no one else has touched them in the meantime,
494 * although we could add these pages to a global reuse list for
495 * shrink_active_list to pick up before reclaiming other pages.
497 * NB: This interface discards data rather than pushes it out to swap,
498 * as some implementations do. This has performance implications for
499 * applications like large transactional databases which want to discard
500 * pages in anonymous maps after committing to backing store the data
501 * that was kept in them. There is no reason to write this data out to
502 * the swap area if the application is discarding it.
504 * An interface that causes the system to free clean pages and flush
505 * dirty pages is already available as msync(MS_INVALIDATE).
507 static long madvise_dontneed_single_vma(struct vm_area_struct
*vma
,
508 unsigned long start
, unsigned long end
)
510 zap_page_range(vma
, start
, end
- start
);
514 static long madvise_dontneed_free(struct vm_area_struct
*vma
,
515 struct vm_area_struct
**prev
,
516 unsigned long start
, unsigned long end
,
520 if (!can_madv_dontneed_vma(vma
))
523 if (!userfaultfd_remove(vma
, start
, end
)) {
524 *prev
= NULL
; /* mmap_sem has been dropped, prev is stale */
526 down_read(¤t
->mm
->mmap_sem
);
527 vma
= find_vma(current
->mm
, start
);
530 if (start
< vma
->vm_start
) {
532 * This "vma" under revalidation is the one
533 * with the lowest vma->vm_start where start
534 * is also < vma->vm_end. If start <
535 * vma->vm_start it means an hole materialized
536 * in the user address space within the
537 * virtual range passed to MADV_DONTNEED
542 if (!can_madv_dontneed_vma(vma
))
544 if (end
> vma
->vm_end
) {
546 * Don't fail if end > vma->vm_end. If the old
547 * vma was splitted while the mmap_sem was
548 * released the effect of the concurrent
549 * operation may not cause madvise() to
550 * have an undefined result. There may be an
551 * adjacent next vma that we'll walk
552 * next. userfaultfd_remove() will generate an
553 * UFFD_EVENT_REMOVE repetition on the
554 * end-vma->vm_end range, but the manager can
555 * handle a repetition fine.
559 VM_WARN_ON(start
>= end
);
562 if (behavior
== MADV_DONTNEED
)
563 return madvise_dontneed_single_vma(vma
, start
, end
);
564 else if (behavior
== MADV_FREE
)
565 return madvise_free_single_vma(vma
, start
, end
);
571 * Application wants to free up the pages and associated backing store.
572 * This is effectively punching a hole into the middle of a file.
574 static long madvise_remove(struct vm_area_struct
*vma
,
575 struct vm_area_struct
**prev
,
576 unsigned long start
, unsigned long end
)
582 *prev
= NULL
; /* tell sys_madvise we drop mmap_sem */
584 if (vma
->vm_flags
& VM_LOCKED
)
589 if (!f
|| !f
->f_mapping
|| !f
->f_mapping
->host
) {
593 if ((vma
->vm_flags
& (VM_SHARED
|VM_WRITE
)) != (VM_SHARED
|VM_WRITE
))
596 offset
= (loff_t
)(start
- vma
->vm_start
)
597 + ((loff_t
)vma
->vm_pgoff
<< PAGE_SHIFT
);
600 * Filesystem's fallocate may need to take i_mutex. We need to
601 * explicitly grab a reference because the vma (and hence the
602 * vma's reference to the file) can go away as soon as we drop
606 if (userfaultfd_remove(vma
, start
, end
)) {
607 /* mmap_sem was not released by userfaultfd_remove() */
608 up_read(¤t
->mm
->mmap_sem
);
610 error
= vfs_fallocate(f
,
611 FALLOC_FL_PUNCH_HOLE
| FALLOC_FL_KEEP_SIZE
,
612 offset
, end
- start
);
614 down_read(¤t
->mm
->mmap_sem
);
618 #ifdef CONFIG_MEMORY_FAILURE
620 * Error injection support for memory error handling.
622 static int madvise_inject_error(int behavior
,
623 unsigned long start
, unsigned long end
)
629 if (!capable(CAP_SYS_ADMIN
))
633 for (; start
< end
; start
+= PAGE_SIZE
<< order
) {
636 ret
= get_user_pages_fast(start
, 1, 0, &page
);
641 * When soft offlining hugepages, after migrating the page
642 * we dissolve it, therefore in the second loop "page" will
643 * no longer be a compound page, and order will be 0.
645 order
= compound_order(compound_head(page
));
647 if (PageHWPoison(page
)) {
652 if (behavior
== MADV_SOFT_OFFLINE
) {
653 pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
654 page_to_pfn(page
), start
);
656 ret
= soft_offline_page(page
, MF_COUNT_INCREASED
);
661 pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
662 page_to_pfn(page
), start
);
664 ret
= memory_failure(page_to_pfn(page
), 0, MF_COUNT_INCREASED
);
669 /* Ensure that all poisoned pages are removed from per-cpu lists */
670 for_each_populated_zone(zone
)
671 drain_all_pages(zone
);
678 madvise_vma(struct vm_area_struct
*vma
, struct vm_area_struct
**prev
,
679 unsigned long start
, unsigned long end
, int behavior
)
683 return madvise_remove(vma
, prev
, start
, end
);
685 return madvise_willneed(vma
, prev
, start
, end
);
688 return madvise_dontneed_free(vma
, prev
, start
, end
, behavior
);
690 return madvise_behavior(vma
, prev
, start
, end
, behavior
);
695 madvise_behavior_valid(int behavior
)
701 case MADV_SEQUENTIAL
:
709 case MADV_UNMERGEABLE
:
711 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
713 case MADV_NOHUGEPAGE
:
717 case MADV_WIPEONFORK
:
718 case MADV_KEEPONFORK
:
719 #ifdef CONFIG_MEMORY_FAILURE
720 case MADV_SOFT_OFFLINE
:
731 * The madvise(2) system call.
733 * Applications can use madvise() to advise the kernel how it should
734 * handle paging I/O in this VM area. The idea is to help the kernel
735 * use appropriate read-ahead and caching techniques. The information
736 * provided is advisory only, and can be safely disregarded by the
737 * kernel without affecting the correct operation of the application.
740 * MADV_NORMAL - the default behavior is to read clusters. This
741 * results in some read-ahead and read-behind.
742 * MADV_RANDOM - the system should read the minimum amount of data
743 * on any access, since it is unlikely that the appli-
744 * cation will need more than what it asks for.
745 * MADV_SEQUENTIAL - pages in the given range will probably be accessed
746 * once, so they can be aggressively read ahead, and
747 * can be freed soon after they are accessed.
748 * MADV_WILLNEED - the application is notifying the system to read
750 * MADV_DONTNEED - the application is finished with the given range,
751 * so the kernel can free resources associated with it.
752 * MADV_FREE - the application marks pages in the given range as lazy free,
753 * where actual purges are postponed until memory pressure happens.
754 * MADV_REMOVE - the application wants to free up the given range of
755 * pages and associated backing store.
756 * MADV_DONTFORK - omit this area from child's address space when forking:
757 * typically, to avoid COWing pages pinned by get_user_pages().
758 * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
759 * MADV_WIPEONFORK - present the child process with zero-filled memory in this
760 * range after a fork.
761 * MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
762 * MADV_HWPOISON - trigger memory error handler as if the given memory range
763 * were corrupted by unrecoverable hardware memory failure.
764 * MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
765 * MADV_MERGEABLE - the application recommends that KSM try to merge pages in
766 * this area with pages of identical content from other such areas.
767 * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
768 * MADV_HUGEPAGE - the application wants to back the given range by transparent
769 * huge pages in the future. Existing pages might be coalesced and
770 * new pages might be allocated as THP.
771 * MADV_NOHUGEPAGE - mark the given range as not worth being backed by
772 * transparent huge pages so the existing pages will not be
773 * coalesced into THP and new pages will not be allocated as THP.
774 * MADV_DONTDUMP - the application wants to prevent pages in the given range
775 * from being included in its core dump.
776 * MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
780 * -EINVAL - start + len < 0, start is not page-aligned,
781 * "behavior" is not a valid value, or application
782 * is attempting to release locked or shared pages,
783 * or the specified address range includes file, Huge TLB,
784 * MAP_SHARED or VMPFNMAP range.
785 * -ENOMEM - addresses in the specified range are not currently
786 * mapped, or are outside the AS of the process.
787 * -EIO - an I/O error occurred while paging in data.
788 * -EBADF - map exists, but area maps something that isn't a file.
789 * -EAGAIN - a kernel resource was temporarily unavailable.
791 SYSCALL_DEFINE3(madvise
, unsigned long, start
, size_t, len_in
, int, behavior
)
793 unsigned long end
, tmp
;
794 struct vm_area_struct
*vma
, *prev
;
795 int unmapped_error
= 0;
799 struct blk_plug plug
;
801 if (!madvise_behavior_valid(behavior
))
804 if (start
& ~PAGE_MASK
)
806 len
= (len_in
+ ~PAGE_MASK
) & PAGE_MASK
;
808 /* Check to see whether len was rounded up from small -ve to zero */
820 #ifdef CONFIG_MEMORY_FAILURE
821 if (behavior
== MADV_HWPOISON
|| behavior
== MADV_SOFT_OFFLINE
)
822 return madvise_inject_error(behavior
, start
, start
+ len_in
);
825 write
= madvise_need_mmap_write(behavior
);
827 if (down_write_killable(¤t
->mm
->mmap_sem
))
830 down_read(¤t
->mm
->mmap_sem
);
834 * If the interval [start,end) covers some unmapped address
835 * ranges, just ignore them, but return -ENOMEM at the end.
836 * - different from the way of handling in mlock etc.
838 vma
= find_vma_prev(current
->mm
, start
, &prev
);
839 if (vma
&& start
> vma
->vm_start
)
842 blk_start_plug(&plug
);
844 /* Still start < end. */
849 /* Here start < (end|vma->vm_end). */
850 if (start
< vma
->vm_start
) {
851 unmapped_error
= -ENOMEM
;
852 start
= vma
->vm_start
;
857 /* Here vma->vm_start <= start < (end|vma->vm_end) */
862 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
863 error
= madvise_vma(vma
, &prev
, start
, tmp
, behavior
);
867 if (prev
&& start
< prev
->vm_end
)
868 start
= prev
->vm_end
;
869 error
= unmapped_error
;
874 else /* madvise_remove dropped mmap_sem */
875 vma
= find_vma(current
->mm
, start
);
878 blk_finish_plug(&plug
);
880 up_write(¤t
->mm
->mmap_sem
);
882 up_read(¤t
->mm
->mmap_sem
);