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/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/uio.h>
22 #include <linux/ksm.h>
24 #include <linux/file.h>
25 #include <linux/blkdev.h>
26 #include <linux/backing-dev.h>
27 #include <linux/pagewalk.h>
28 #include <linux/swap.h>
29 #include <linux/swapops.h>
30 #include <linux/shmem_fs.h>
31 #include <linux/mmu_notifier.h>
37 struct madvise_walk_private
{
38 struct mmu_gather
*tlb
;
43 * Any behaviour which results in changes to the vma->vm_flags needs to
44 * take mmap_lock for writing. Others, which simply traverse vmas, need
45 * to only take it for reading.
47 static int madvise_need_mmap_write(int behavior
)
58 /* be safe, default to 1. list exceptions explicitly */
64 * We can potentially split a vm area into separate
65 * areas, each area with its own behavior.
67 static long madvise_behavior(struct vm_area_struct
*vma
,
68 struct vm_area_struct
**prev
,
69 unsigned long start
, unsigned long end
, int behavior
)
71 struct mm_struct
*mm
= vma
->vm_mm
;
74 unsigned long new_flags
= vma
->vm_flags
;
78 new_flags
= new_flags
& ~VM_RAND_READ
& ~VM_SEQ_READ
;
81 new_flags
= (new_flags
& ~VM_RAND_READ
) | VM_SEQ_READ
;
84 new_flags
= (new_flags
& ~VM_SEQ_READ
) | VM_RAND_READ
;
87 new_flags
|= VM_DONTCOPY
;
90 if (vma
->vm_flags
& VM_IO
) {
94 new_flags
&= ~VM_DONTCOPY
;
97 /* MADV_WIPEONFORK is only supported on anonymous memory. */
98 if (vma
->vm_file
|| vma
->vm_flags
& VM_SHARED
) {
102 new_flags
|= VM_WIPEONFORK
;
104 case MADV_KEEPONFORK
:
105 new_flags
&= ~VM_WIPEONFORK
;
108 new_flags
|= VM_DONTDUMP
;
111 if (!is_vm_hugetlb_page(vma
) && new_flags
& VM_SPECIAL
) {
115 new_flags
&= ~VM_DONTDUMP
;
118 case MADV_UNMERGEABLE
:
119 error
= ksm_madvise(vma
, start
, end
, behavior
, &new_flags
);
121 goto out_convert_errno
;
124 case MADV_NOHUGEPAGE
:
125 error
= hugepage_madvise(vma
, &new_flags
, behavior
);
127 goto out_convert_errno
;
131 if (new_flags
== vma
->vm_flags
) {
136 pgoff
= vma
->vm_pgoff
+ ((start
- vma
->vm_start
) >> PAGE_SHIFT
);
137 *prev
= vma_merge(mm
, *prev
, start
, end
, new_flags
, vma
->anon_vma
,
138 vma
->vm_file
, pgoff
, vma_policy(vma
),
139 vma
->vm_userfaultfd_ctx
);
147 if (start
!= vma
->vm_start
) {
148 if (unlikely(mm
->map_count
>= sysctl_max_map_count
)) {
152 error
= __split_vma(mm
, vma
, start
, 1);
154 goto out_convert_errno
;
157 if (end
!= vma
->vm_end
) {
158 if (unlikely(mm
->map_count
>= sysctl_max_map_count
)) {
162 error
= __split_vma(mm
, vma
, end
, 0);
164 goto out_convert_errno
;
169 * vm_flags is protected by the mmap_lock held in write mode.
171 vma
->vm_flags
= new_flags
;
175 * madvise() returns EAGAIN if kernel resources, such as
176 * slab, are temporarily unavailable.
178 if (error
== -ENOMEM
)
185 static int swapin_walk_pmd_entry(pmd_t
*pmd
, unsigned long start
,
186 unsigned long end
, struct mm_walk
*walk
)
189 struct vm_area_struct
*vma
= walk
->private;
192 if (pmd_none_or_trans_huge_or_clear_bad(pmd
))
195 for (index
= start
; index
!= end
; index
+= PAGE_SIZE
) {
201 orig_pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, start
, &ptl
);
202 pte
= *(orig_pte
+ ((index
- start
) / PAGE_SIZE
));
203 pte_unmap_unlock(orig_pte
, ptl
);
205 if (pte_present(pte
) || pte_none(pte
))
207 entry
= pte_to_swp_entry(pte
);
208 if (unlikely(non_swap_entry(entry
)))
211 page
= read_swap_cache_async(entry
, GFP_HIGHUSER_MOVABLE
,
220 static const struct mm_walk_ops swapin_walk_ops
= {
221 .pmd_entry
= swapin_walk_pmd_entry
,
224 static void force_shm_swapin_readahead(struct vm_area_struct
*vma
,
225 unsigned long start
, unsigned long end
,
226 struct address_space
*mapping
)
228 XA_STATE(xas
, &mapping
->i_pages
, linear_page_index(vma
, start
));
229 pgoff_t end_index
= linear_page_index(vma
, end
+ PAGE_SIZE
- 1);
233 xas_for_each(&xas
, page
, end_index
) {
236 if (!xa_is_value(page
))
241 swap
= radix_to_swp_entry(page
);
242 page
= read_swap_cache_async(swap
, GFP_HIGHUSER_MOVABLE
,
251 lru_add_drain(); /* Push any new pages onto the LRU now */
253 #endif /* CONFIG_SWAP */
256 * Schedule all required I/O operations. Do not wait for completion.
258 static long madvise_willneed(struct vm_area_struct
*vma
,
259 struct vm_area_struct
**prev
,
260 unsigned long start
, unsigned long end
)
262 struct mm_struct
*mm
= vma
->vm_mm
;
263 struct file
*file
= vma
->vm_file
;
269 walk_page_range(vma
->vm_mm
, start
, end
, &swapin_walk_ops
, vma
);
270 lru_add_drain(); /* Push any new pages onto the LRU now */
274 if (shmem_mapping(file
->f_mapping
)) {
275 force_shm_swapin_readahead(vma
, start
, end
,
284 if (IS_DAX(file_inode(file
))) {
285 /* no bad return value, but ignore advice */
290 * Filesystem's fadvise may need to take various locks. We need to
291 * explicitly grab a reference because the vma (and hence the
292 * vma's reference to the file) can go away as soon as we drop
295 *prev
= NULL
; /* tell sys_madvise we drop mmap_lock */
297 offset
= (loff_t
)(start
- vma
->vm_start
)
298 + ((loff_t
)vma
->vm_pgoff
<< PAGE_SHIFT
);
299 mmap_read_unlock(mm
);
300 vfs_fadvise(file
, offset
, end
- start
, POSIX_FADV_WILLNEED
);
306 static int madvise_cold_or_pageout_pte_range(pmd_t
*pmd
,
307 unsigned long addr
, unsigned long end
,
308 struct mm_walk
*walk
)
310 struct madvise_walk_private
*private = walk
->private;
311 struct mmu_gather
*tlb
= private->tlb
;
312 bool pageout
= private->pageout
;
313 struct mm_struct
*mm
= tlb
->mm
;
314 struct vm_area_struct
*vma
= walk
->vma
;
315 pte_t
*orig_pte
, *pte
, ptent
;
317 struct page
*page
= NULL
;
318 LIST_HEAD(page_list
);
320 if (fatal_signal_pending(current
))
323 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
324 if (pmd_trans_huge(*pmd
)) {
326 unsigned long next
= pmd_addr_end(addr
, end
);
328 tlb_change_page_size(tlb
, HPAGE_PMD_SIZE
);
329 ptl
= pmd_trans_huge_lock(pmd
, vma
);
334 if (is_huge_zero_pmd(orig_pmd
))
337 if (unlikely(!pmd_present(orig_pmd
))) {
338 VM_BUG_ON(thp_migration_supported() &&
339 !is_pmd_migration_entry(orig_pmd
));
343 page
= pmd_page(orig_pmd
);
345 /* Do not interfere with other mappings of this page */
346 if (page_mapcount(page
) != 1)
349 if (next
- addr
!= HPAGE_PMD_SIZE
) {
355 err
= split_huge_page(page
);
363 if (pmd_young(orig_pmd
)) {
364 pmdp_invalidate(vma
, addr
, pmd
);
365 orig_pmd
= pmd_mkold(orig_pmd
);
367 set_pmd_at(mm
, addr
, pmd
, orig_pmd
);
368 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
371 ClearPageReferenced(page
);
372 test_and_clear_page_young(page
);
374 if (!isolate_lru_page(page
)) {
375 if (PageUnevictable(page
))
376 putback_lru_page(page
);
378 list_add(&page
->lru
, &page_list
);
381 deactivate_page(page
);
385 reclaim_pages(&page_list
);
390 if (pmd_trans_unstable(pmd
))
393 tlb_change_page_size(tlb
, PAGE_SIZE
);
394 orig_pte
= pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, addr
, &ptl
);
395 flush_tlb_batched_pending(mm
);
396 arch_enter_lazy_mmu_mode();
397 for (; addr
< end
; pte
++, addr
+= PAGE_SIZE
) {
403 if (!pte_present(ptent
))
406 page
= vm_normal_page(vma
, addr
, ptent
);
411 * Creating a THP page is expensive so split it only if we
412 * are sure it's worth. Split it if we are only owner.
414 if (PageTransCompound(page
)) {
415 if (page_mapcount(page
) != 1)
418 if (!trylock_page(page
)) {
422 pte_unmap_unlock(orig_pte
, ptl
);
423 if (split_huge_page(page
)) {
426 pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
431 pte
= pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
437 /* Do not interfere with other mappings of this page */
438 if (page_mapcount(page
) != 1)
441 VM_BUG_ON_PAGE(PageTransCompound(page
), page
);
443 if (pte_young(ptent
)) {
444 ptent
= ptep_get_and_clear_full(mm
, addr
, pte
,
446 ptent
= pte_mkold(ptent
);
447 set_pte_at(mm
, addr
, pte
, ptent
);
448 tlb_remove_tlb_entry(tlb
, pte
, addr
);
452 * We are deactivating a page for accelerating reclaiming.
453 * VM couldn't reclaim the page unless we clear PG_young.
454 * As a side effect, it makes confuse idle-page tracking
455 * because they will miss recent referenced history.
457 ClearPageReferenced(page
);
458 test_and_clear_page_young(page
);
460 if (!isolate_lru_page(page
)) {
461 if (PageUnevictable(page
))
462 putback_lru_page(page
);
464 list_add(&page
->lru
, &page_list
);
467 deactivate_page(page
);
470 arch_leave_lazy_mmu_mode();
471 pte_unmap_unlock(orig_pte
, ptl
);
473 reclaim_pages(&page_list
);
479 static const struct mm_walk_ops cold_walk_ops
= {
480 .pmd_entry
= madvise_cold_or_pageout_pte_range
,
483 static void madvise_cold_page_range(struct mmu_gather
*tlb
,
484 struct vm_area_struct
*vma
,
485 unsigned long addr
, unsigned long end
)
487 struct madvise_walk_private walk_private
= {
492 tlb_start_vma(tlb
, vma
);
493 walk_page_range(vma
->vm_mm
, addr
, end
, &cold_walk_ops
, &walk_private
);
494 tlb_end_vma(tlb
, vma
);
497 static long madvise_cold(struct vm_area_struct
*vma
,
498 struct vm_area_struct
**prev
,
499 unsigned long start_addr
, unsigned long end_addr
)
501 struct mm_struct
*mm
= vma
->vm_mm
;
502 struct mmu_gather tlb
;
505 if (!can_madv_lru_vma(vma
))
509 tlb_gather_mmu(&tlb
, mm
);
510 madvise_cold_page_range(&tlb
, vma
, start_addr
, end_addr
);
511 tlb_finish_mmu(&tlb
);
516 static void madvise_pageout_page_range(struct mmu_gather
*tlb
,
517 struct vm_area_struct
*vma
,
518 unsigned long addr
, unsigned long end
)
520 struct madvise_walk_private walk_private
= {
525 tlb_start_vma(tlb
, vma
);
526 walk_page_range(vma
->vm_mm
, addr
, end
, &cold_walk_ops
, &walk_private
);
527 tlb_end_vma(tlb
, vma
);
530 static inline bool can_do_pageout(struct vm_area_struct
*vma
)
532 if (vma_is_anonymous(vma
))
537 * paging out pagecache only for non-anonymous mappings that correspond
538 * to the files the calling process could (if tried) open for writing;
539 * otherwise we'd be including shared non-exclusive mappings, which
540 * opens a side channel.
542 return inode_owner_or_capable(&init_user_ns
,
543 file_inode(vma
->vm_file
)) ||
544 file_permission(vma
->vm_file
, MAY_WRITE
) == 0;
547 static long madvise_pageout(struct vm_area_struct
*vma
,
548 struct vm_area_struct
**prev
,
549 unsigned long start_addr
, unsigned long end_addr
)
551 struct mm_struct
*mm
= vma
->vm_mm
;
552 struct mmu_gather tlb
;
555 if (!can_madv_lru_vma(vma
))
558 if (!can_do_pageout(vma
))
562 tlb_gather_mmu(&tlb
, mm
);
563 madvise_pageout_page_range(&tlb
, vma
, start_addr
, end_addr
);
564 tlb_finish_mmu(&tlb
);
569 static int madvise_free_pte_range(pmd_t
*pmd
, unsigned long addr
,
570 unsigned long end
, struct mm_walk
*walk
)
573 struct mmu_gather
*tlb
= walk
->private;
574 struct mm_struct
*mm
= tlb
->mm
;
575 struct vm_area_struct
*vma
= walk
->vma
;
577 pte_t
*orig_pte
, *pte
, ptent
;
582 next
= pmd_addr_end(addr
, end
);
583 if (pmd_trans_huge(*pmd
))
584 if (madvise_free_huge_pmd(tlb
, vma
, pmd
, addr
, next
))
587 if (pmd_trans_unstable(pmd
))
590 tlb_change_page_size(tlb
, PAGE_SIZE
);
591 orig_pte
= pte
= pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
592 flush_tlb_batched_pending(mm
);
593 arch_enter_lazy_mmu_mode();
594 for (; addr
!= end
; pte
++, addr
+= PAGE_SIZE
) {
600 * If the pte has swp_entry, just clear page table to
601 * prevent swap-in which is more expensive rather than
602 * (page allocation + zeroing).
604 if (!pte_present(ptent
)) {
607 entry
= pte_to_swp_entry(ptent
);
608 if (non_swap_entry(entry
))
611 free_swap_and_cache(entry
);
612 pte_clear_not_present_full(mm
, addr
, pte
, tlb
->fullmm
);
616 page
= vm_normal_page(vma
, addr
, ptent
);
621 * If pmd isn't transhuge but the page is THP and
622 * is owned by only this process, split it and
623 * deactivate all pages.
625 if (PageTransCompound(page
)) {
626 if (page_mapcount(page
) != 1)
629 if (!trylock_page(page
)) {
633 pte_unmap_unlock(orig_pte
, ptl
);
634 if (split_huge_page(page
)) {
637 pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
642 pte
= pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
648 VM_BUG_ON_PAGE(PageTransCompound(page
), page
);
650 if (PageSwapCache(page
) || PageDirty(page
)) {
651 if (!trylock_page(page
))
654 * If page is shared with others, we couldn't clear
655 * PG_dirty of the page.
657 if (page_mapcount(page
) != 1) {
662 if (PageSwapCache(page
) && !try_to_free_swap(page
)) {
667 ClearPageDirty(page
);
671 if (pte_young(ptent
) || pte_dirty(ptent
)) {
673 * Some of architecture(ex, PPC) don't update TLB
674 * with set_pte_at and tlb_remove_tlb_entry so for
675 * the portability, remap the pte with old|clean
676 * after pte clearing.
678 ptent
= ptep_get_and_clear_full(mm
, addr
, pte
,
681 ptent
= pte_mkold(ptent
);
682 ptent
= pte_mkclean(ptent
);
683 set_pte_at(mm
, addr
, pte
, ptent
);
684 tlb_remove_tlb_entry(tlb
, pte
, addr
);
686 mark_page_lazyfree(page
);
690 if (current
->mm
== mm
)
693 add_mm_counter(mm
, MM_SWAPENTS
, nr_swap
);
695 arch_leave_lazy_mmu_mode();
696 pte_unmap_unlock(orig_pte
, ptl
);
702 static const struct mm_walk_ops madvise_free_walk_ops
= {
703 .pmd_entry
= madvise_free_pte_range
,
706 static int madvise_free_single_vma(struct vm_area_struct
*vma
,
707 unsigned long start_addr
, unsigned long end_addr
)
709 struct mm_struct
*mm
= vma
->vm_mm
;
710 struct mmu_notifier_range range
;
711 struct mmu_gather tlb
;
713 /* MADV_FREE works for only anon vma at the moment */
714 if (!vma_is_anonymous(vma
))
717 range
.start
= max(vma
->vm_start
, start_addr
);
718 if (range
.start
>= vma
->vm_end
)
720 range
.end
= min(vma
->vm_end
, end_addr
);
721 if (range
.end
<= vma
->vm_start
)
723 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, vma
, mm
,
724 range
.start
, range
.end
);
727 tlb_gather_mmu(&tlb
, mm
);
728 update_hiwater_rss(mm
);
730 mmu_notifier_invalidate_range_start(&range
);
731 tlb_start_vma(&tlb
, vma
);
732 walk_page_range(vma
->vm_mm
, range
.start
, range
.end
,
733 &madvise_free_walk_ops
, &tlb
);
734 tlb_end_vma(&tlb
, vma
);
735 mmu_notifier_invalidate_range_end(&range
);
736 tlb_finish_mmu(&tlb
);
742 * Application no longer needs these pages. If the pages are dirty,
743 * it's OK to just throw them away. The app will be more careful about
744 * data it wants to keep. Be sure to free swap resources too. The
745 * zap_page_range call sets things up for shrink_active_list to actually free
746 * these pages later if no one else has touched them in the meantime,
747 * although we could add these pages to a global reuse list for
748 * shrink_active_list to pick up before reclaiming other pages.
750 * NB: This interface discards data rather than pushes it out to swap,
751 * as some implementations do. This has performance implications for
752 * applications like large transactional databases which want to discard
753 * pages in anonymous maps after committing to backing store the data
754 * that was kept in them. There is no reason to write this data out to
755 * the swap area if the application is discarding it.
757 * An interface that causes the system to free clean pages and flush
758 * dirty pages is already available as msync(MS_INVALIDATE).
760 static long madvise_dontneed_single_vma(struct vm_area_struct
*vma
,
761 unsigned long start
, unsigned long end
)
763 zap_page_range(vma
, start
, end
- start
);
767 static long madvise_dontneed_free(struct vm_area_struct
*vma
,
768 struct vm_area_struct
**prev
,
769 unsigned long start
, unsigned long end
,
772 struct mm_struct
*mm
= vma
->vm_mm
;
775 if (!can_madv_lru_vma(vma
))
778 if (!userfaultfd_remove(vma
, start
, end
)) {
779 *prev
= NULL
; /* mmap_lock has been dropped, prev is stale */
782 vma
= find_vma(mm
, start
);
785 if (start
< vma
->vm_start
) {
787 * This "vma" under revalidation is the one
788 * with the lowest vma->vm_start where start
789 * is also < vma->vm_end. If start <
790 * vma->vm_start it means an hole materialized
791 * in the user address space within the
792 * virtual range passed to MADV_DONTNEED
797 if (!can_madv_lru_vma(vma
))
799 if (end
> vma
->vm_end
) {
801 * Don't fail if end > vma->vm_end. If the old
802 * vma was splitted while the mmap_lock was
803 * released the effect of the concurrent
804 * operation may not cause madvise() to
805 * have an undefined result. There may be an
806 * adjacent next vma that we'll walk
807 * next. userfaultfd_remove() will generate an
808 * UFFD_EVENT_REMOVE repetition on the
809 * end-vma->vm_end range, but the manager can
810 * handle a repetition fine.
814 VM_WARN_ON(start
>= end
);
817 if (behavior
== MADV_DONTNEED
)
818 return madvise_dontneed_single_vma(vma
, start
, end
);
819 else if (behavior
== MADV_FREE
)
820 return madvise_free_single_vma(vma
, start
, end
);
826 * Application wants to free up the pages and associated backing store.
827 * This is effectively punching a hole into the middle of a file.
829 static long madvise_remove(struct vm_area_struct
*vma
,
830 struct vm_area_struct
**prev
,
831 unsigned long start
, unsigned long end
)
836 struct mm_struct
*mm
= vma
->vm_mm
;
838 *prev
= NULL
; /* tell sys_madvise we drop mmap_lock */
840 if (vma
->vm_flags
& VM_LOCKED
)
845 if (!f
|| !f
->f_mapping
|| !f
->f_mapping
->host
) {
849 if ((vma
->vm_flags
& (VM_SHARED
|VM_WRITE
)) != (VM_SHARED
|VM_WRITE
))
852 offset
= (loff_t
)(start
- vma
->vm_start
)
853 + ((loff_t
)vma
->vm_pgoff
<< PAGE_SHIFT
);
856 * Filesystem's fallocate may need to take i_mutex. We need to
857 * explicitly grab a reference because the vma (and hence the
858 * vma's reference to the file) can go away as soon as we drop
862 if (userfaultfd_remove(vma
, start
, end
)) {
863 /* mmap_lock was not released by userfaultfd_remove() */
864 mmap_read_unlock(mm
);
866 error
= vfs_fallocate(f
,
867 FALLOC_FL_PUNCH_HOLE
| FALLOC_FL_KEEP_SIZE
,
868 offset
, end
- start
);
874 #ifdef CONFIG_MEMORY_FAILURE
876 * Error injection support for memory error handling.
878 static int madvise_inject_error(int behavior
,
879 unsigned long start
, unsigned long end
)
883 if (!capable(CAP_SYS_ADMIN
))
887 for (; start
< end
; start
+= size
) {
892 ret
= get_user_pages_fast(start
, 1, 0, &page
);
895 pfn
= page_to_pfn(page
);
898 * When soft offlining hugepages, after migrating the page
899 * we dissolve it, therefore in the second loop "page" will
900 * no longer be a compound page.
902 size
= page_size(compound_head(page
));
904 if (behavior
== MADV_SOFT_OFFLINE
) {
905 pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
907 ret
= soft_offline_page(pfn
, MF_COUNT_INCREASED
);
909 pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
911 ret
= memory_failure(pfn
, MF_COUNT_INCREASED
);
923 madvise_vma(struct vm_area_struct
*vma
, struct vm_area_struct
**prev
,
924 unsigned long start
, unsigned long end
, int behavior
)
928 return madvise_remove(vma
, prev
, start
, end
);
930 return madvise_willneed(vma
, prev
, start
, end
);
932 return madvise_cold(vma
, prev
, start
, end
);
934 return madvise_pageout(vma
, prev
, start
, end
);
937 return madvise_dontneed_free(vma
, prev
, start
, end
, behavior
);
939 return madvise_behavior(vma
, prev
, start
, end
, behavior
);
944 madvise_behavior_valid(int behavior
)
950 case MADV_SEQUENTIAL
:
960 case MADV_UNMERGEABLE
:
962 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
964 case MADV_NOHUGEPAGE
:
968 case MADV_WIPEONFORK
:
969 case MADV_KEEPONFORK
:
970 #ifdef CONFIG_MEMORY_FAILURE
971 case MADV_SOFT_OFFLINE
:
982 process_madvise_behavior_valid(int behavior
)
994 * The madvise(2) system call.
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.
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
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 * MADV_COLD - the application is not expected to use this memory soon,
1041 * deactivate pages in this range so that they can be reclaimed
1042 * easily if memory pressure hanppens.
1043 * MADV_PAGEOUT - the application is not expected to use this memory soon,
1044 * page out the pages in this range immediately.
1048 * -EINVAL - start + len < 0, start is not page-aligned,
1049 * "behavior" is not a valid value, or application
1050 * is attempting to release locked or shared pages,
1051 * or the specified address range includes file, Huge TLB,
1052 * MAP_SHARED or VMPFNMAP range.
1053 * -ENOMEM - addresses in the specified range are not currently
1054 * mapped, or are outside the AS of the process.
1055 * -EIO - an I/O error occurred while paging in data.
1056 * -EBADF - map exists, but area maps something that isn't a file.
1057 * -EAGAIN - a kernel resource was temporarily unavailable.
1059 int do_madvise(struct mm_struct
*mm
, unsigned long start
, size_t len_in
, int behavior
)
1061 unsigned long end
, tmp
;
1062 struct vm_area_struct
*vma
, *prev
;
1063 int unmapped_error
= 0;
1064 int error
= -EINVAL
;
1067 struct blk_plug plug
;
1069 start
= untagged_addr(start
);
1071 if (!madvise_behavior_valid(behavior
))
1074 if (!PAGE_ALIGNED(start
))
1076 len
= PAGE_ALIGN(len_in
);
1078 /* Check to see whether len was rounded up from small -ve to zero */
1090 #ifdef CONFIG_MEMORY_FAILURE
1091 if (behavior
== MADV_HWPOISON
|| behavior
== MADV_SOFT_OFFLINE
)
1092 return madvise_inject_error(behavior
, start
, start
+ len_in
);
1095 write
= madvise_need_mmap_write(behavior
);
1097 if (mmap_write_lock_killable(mm
))
1104 * If the interval [start,end) covers some unmapped address
1105 * ranges, just ignore them, but return -ENOMEM at the end.
1106 * - different from the way of handling in mlock etc.
1108 vma
= find_vma_prev(mm
, start
, &prev
);
1109 if (vma
&& start
> vma
->vm_start
)
1112 blk_start_plug(&plug
);
1114 /* Still start < end. */
1119 /* Here start < (end|vma->vm_end). */
1120 if (start
< vma
->vm_start
) {
1121 unmapped_error
= -ENOMEM
;
1122 start
= vma
->vm_start
;
1127 /* Here vma->vm_start <= start < (end|vma->vm_end) */
1132 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
1133 error
= madvise_vma(vma
, &prev
, start
, tmp
, behavior
);
1137 if (prev
&& start
< prev
->vm_end
)
1138 start
= prev
->vm_end
;
1139 error
= unmapped_error
;
1143 vma
= prev
->vm_next
;
1144 else /* madvise_remove dropped mmap_lock */
1145 vma
= find_vma(mm
, start
);
1148 blk_finish_plug(&plug
);
1150 mmap_write_unlock(mm
);
1152 mmap_read_unlock(mm
);
1157 SYSCALL_DEFINE3(madvise
, unsigned long, start
, size_t, len_in
, int, behavior
)
1159 return do_madvise(current
->mm
, start
, len_in
, behavior
);
1162 SYSCALL_DEFINE5(process_madvise
, int, pidfd
, const struct iovec __user
*, vec
,
1163 size_t, vlen
, int, behavior
, unsigned int, flags
)
1166 struct iovec iovstack
[UIO_FASTIOV
], iovec
;
1167 struct iovec
*iov
= iovstack
;
1168 struct iov_iter iter
;
1170 struct task_struct
*task
;
1171 struct mm_struct
*mm
;
1173 unsigned int f_flags
;
1180 ret
= import_iovec(READ
, vec
, vlen
, ARRAY_SIZE(iovstack
), &iov
, &iter
);
1184 pid
= pidfd_get_pid(pidfd
, &f_flags
);
1190 task
= get_pid_task(pid
, PIDTYPE_PID
);
1196 if (!process_madvise_behavior_valid(behavior
)) {
1201 /* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */
1202 mm
= mm_access(task
, PTRACE_MODE_READ_FSCREDS
);
1203 if (IS_ERR_OR_NULL(mm
)) {
1204 ret
= IS_ERR(mm
) ? PTR_ERR(mm
) : -ESRCH
;
1209 * Require CAP_SYS_NICE for influencing process performance. Note that
1210 * only non-destructive hints are currently supported.
1212 if (!capable(CAP_SYS_NICE
)) {
1217 total_len
= iov_iter_count(&iter
);
1219 while (iov_iter_count(&iter
)) {
1220 iovec
= iov_iter_iovec(&iter
);
1221 ret
= do_madvise(mm
, (unsigned long)iovec
.iov_base
,
1222 iovec
.iov_len
, behavior
);
1225 iov_iter_advance(&iter
, iovec
.iov_len
);
1229 ret
= total_len
- iov_iter_count(&iter
);
1234 put_task_struct(task
);