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/mm_inline.h>
22 #include <linux/string.h>
23 #include <linux/uio.h>
24 #include <linux/ksm.h>
26 #include <linux/file.h>
27 #include <linux/blkdev.h>
28 #include <linux/backing-dev.h>
29 #include <linux/pagewalk.h>
30 #include <linux/swap.h>
31 #include <linux/swapops.h>
32 #include <linux/shmem_fs.h>
33 #include <linux/mmu_notifier.h>
40 struct madvise_walk_private
{
41 struct mmu_gather
*tlb
;
46 * Any behaviour which results in changes to the vma->vm_flags needs to
47 * take mmap_lock for writing. Others, which simply traverse vmas, need
48 * to only take it for reading.
50 static int madvise_need_mmap_write(int behavior
)
56 case MADV_DONTNEED_LOCKED
:
60 case MADV_POPULATE_READ
:
61 case MADV_POPULATE_WRITE
:
65 /* be safe, default to 1. list exceptions explicitly */
70 #ifdef CONFIG_ANON_VMA_NAME
71 struct anon_vma_name
*anon_vma_name_alloc(const char *name
)
73 struct anon_vma_name
*anon_name
;
76 /* Add 1 for NUL terminator at the end of the anon_name->name */
77 count
= strlen(name
) + 1;
78 anon_name
= kmalloc(struct_size(anon_name
, name
, count
), GFP_KERNEL
);
80 kref_init(&anon_name
->kref
);
81 memcpy(anon_name
->name
, name
, count
);
87 void anon_vma_name_free(struct kref
*kref
)
89 struct anon_vma_name
*anon_name
=
90 container_of(kref
, struct anon_vma_name
, kref
);
94 struct anon_vma_name
*anon_vma_name(struct vm_area_struct
*vma
)
96 mmap_assert_locked(vma
->vm_mm
);
98 return vma
->anon_name
;
101 /* mmap_lock should be write-locked */
102 static int replace_anon_vma_name(struct vm_area_struct
*vma
,
103 struct anon_vma_name
*anon_name
)
105 struct anon_vma_name
*orig_name
= anon_vma_name(vma
);
108 vma
->anon_name
= NULL
;
109 anon_vma_name_put(orig_name
);
113 if (anon_vma_name_eq(orig_name
, anon_name
))
116 vma
->anon_name
= anon_vma_name_reuse(anon_name
);
117 anon_vma_name_put(orig_name
);
121 #else /* CONFIG_ANON_VMA_NAME */
122 static int replace_anon_vma_name(struct vm_area_struct
*vma
,
123 struct anon_vma_name
*anon_name
)
130 #endif /* CONFIG_ANON_VMA_NAME */
132 * Update the vm_flags on region of a vma, splitting it or merging it as
133 * necessary. Must be called with mmap_lock held for writing;
134 * Caller should ensure anon_name stability by raising its refcount even when
135 * anon_name belongs to a valid vma because this function might free that vma.
137 static int madvise_update_vma(struct vm_area_struct
*vma
,
138 struct vm_area_struct
**prev
, unsigned long start
,
139 unsigned long end
, unsigned long new_flags
,
140 struct anon_vma_name
*anon_name
)
142 struct mm_struct
*mm
= vma
->vm_mm
;
144 VMA_ITERATOR(vmi
, mm
, start
);
146 if (new_flags
== vma
->vm_flags
&& anon_vma_name_eq(anon_vma_name(vma
), anon_name
)) {
151 vma
= vma_modify_flags_name(&vmi
, *prev
, vma
, start
, end
, new_flags
,
158 /* vm_flags is protected by the mmap_lock held in write mode. */
159 vma_start_write(vma
);
160 vm_flags_reset(vma
, new_flags
);
161 if (!vma
->vm_file
|| vma_is_anon_shmem(vma
)) {
162 error
= replace_anon_vma_name(vma
, anon_name
);
171 static int swapin_walk_pmd_entry(pmd_t
*pmd
, unsigned long start
,
172 unsigned long end
, struct mm_walk
*walk
)
174 struct vm_area_struct
*vma
= walk
->private;
175 struct swap_iocb
*splug
= NULL
;
180 for (addr
= start
; addr
< end
; addr
+= PAGE_SIZE
) {
186 ptep
= pte_offset_map_lock(vma
->vm_mm
, pmd
, addr
, &ptl
);
191 pte
= ptep_get(ptep
);
192 if (!is_swap_pte(pte
))
194 entry
= pte_to_swp_entry(pte
);
195 if (unlikely(non_swap_entry(entry
)))
198 pte_unmap_unlock(ptep
, ptl
);
201 page
= read_swap_cache_async(entry
, GFP_HIGHUSER_MOVABLE
,
208 pte_unmap_unlock(ptep
, ptl
);
209 swap_read_unplug(splug
);
215 static const struct mm_walk_ops swapin_walk_ops
= {
216 .pmd_entry
= swapin_walk_pmd_entry
,
217 .walk_lock
= PGWALK_RDLOCK
,
220 static void shmem_swapin_range(struct vm_area_struct
*vma
,
221 unsigned long start
, unsigned long end
,
222 struct address_space
*mapping
)
224 XA_STATE(xas
, &mapping
->i_pages
, linear_page_index(vma
, start
));
225 pgoff_t end_index
= linear_page_index(vma
, end
) - 1;
227 struct swap_iocb
*splug
= NULL
;
230 xas_for_each(&xas
, page
, end_index
) {
234 if (!xa_is_value(page
))
236 entry
= radix_to_swp_entry(page
);
237 /* There might be swapin error entries in shmem mapping. */
238 if (non_swap_entry(entry
))
241 addr
= vma
->vm_start
+
242 ((xas
.xa_index
- vma
->vm_pgoff
) << PAGE_SHIFT
);
246 page
= read_swap_cache_async(entry
, mapping_gfp_mask(mapping
),
254 swap_read_unplug(splug
);
256 #endif /* CONFIG_SWAP */
259 * Schedule all required I/O operations. Do not wait for completion.
261 static long madvise_willneed(struct vm_area_struct
*vma
,
262 struct vm_area_struct
**prev
,
263 unsigned long start
, unsigned long end
)
265 struct mm_struct
*mm
= vma
->vm_mm
;
266 struct file
*file
= vma
->vm_file
;
272 walk_page_range(vma
->vm_mm
, start
, end
, &swapin_walk_ops
, vma
);
273 lru_add_drain(); /* Push any new pages onto the LRU now */
277 if (shmem_mapping(file
->f_mapping
)) {
278 shmem_swapin_range(vma
, start
, end
, file
->f_mapping
);
279 lru_add_drain(); /* Push any new pages onto the LRU now */
287 if (IS_DAX(file_inode(file
))) {
288 /* no bad return value, but ignore advice */
293 * Filesystem's fadvise may need to take various locks. We need to
294 * explicitly grab a reference because the vma (and hence the
295 * vma's reference to the file) can go away as soon as we drop
298 *prev
= NULL
; /* tell sys_madvise we drop mmap_lock */
300 offset
= (loff_t
)(start
- vma
->vm_start
)
301 + ((loff_t
)vma
->vm_pgoff
<< PAGE_SHIFT
);
302 mmap_read_unlock(mm
);
303 vfs_fadvise(file
, offset
, end
- start
, POSIX_FADV_WILLNEED
);
309 static inline bool can_do_file_pageout(struct vm_area_struct
*vma
)
314 * paging out pagecache only for non-anonymous mappings that correspond
315 * to the files the calling process could (if tried) open for writing;
316 * otherwise we'd be including shared non-exclusive mappings, which
317 * opens a side channel.
319 return inode_owner_or_capable(&nop_mnt_idmap
,
320 file_inode(vma
->vm_file
)) ||
321 file_permission(vma
->vm_file
, MAY_WRITE
) == 0;
324 static int madvise_cold_or_pageout_pte_range(pmd_t
*pmd
,
325 unsigned long addr
, unsigned long end
,
326 struct mm_walk
*walk
)
328 struct madvise_walk_private
*private = walk
->private;
329 struct mmu_gather
*tlb
= private->tlb
;
330 bool pageout
= private->pageout
;
331 struct mm_struct
*mm
= tlb
->mm
;
332 struct vm_area_struct
*vma
= walk
->vma
;
333 pte_t
*start_pte
, *pte
, ptent
;
335 struct folio
*folio
= NULL
;
336 LIST_HEAD(folio_list
);
337 bool pageout_anon_only_filter
;
339 if (fatal_signal_pending(current
))
342 pageout_anon_only_filter
= pageout
&& !vma_is_anonymous(vma
) &&
343 !can_do_file_pageout(vma
);
345 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
346 if (pmd_trans_huge(*pmd
)) {
348 unsigned long next
= pmd_addr_end(addr
, end
);
350 tlb_change_page_size(tlb
, HPAGE_PMD_SIZE
);
351 ptl
= pmd_trans_huge_lock(pmd
, vma
);
356 if (is_huge_zero_pmd(orig_pmd
))
359 if (unlikely(!pmd_present(orig_pmd
))) {
360 VM_BUG_ON(thp_migration_supported() &&
361 !is_pmd_migration_entry(orig_pmd
));
365 folio
= pfn_folio(pmd_pfn(orig_pmd
));
367 /* Do not interfere with other mappings of this folio */
368 if (folio_estimated_sharers(folio
) != 1)
371 if (pageout_anon_only_filter
&& !folio_test_anon(folio
))
374 if (next
- addr
!= HPAGE_PMD_SIZE
) {
380 err
= split_folio(folio
);
388 if (pmd_young(orig_pmd
)) {
389 pmdp_invalidate(vma
, addr
, pmd
);
390 orig_pmd
= pmd_mkold(orig_pmd
);
392 set_pmd_at(mm
, addr
, pmd
, orig_pmd
);
393 tlb_remove_pmd_tlb_entry(tlb
, pmd
, addr
);
396 folio_clear_referenced(folio
);
397 folio_test_clear_young(folio
);
398 if (folio_test_active(folio
))
399 folio_set_workingset(folio
);
401 if (folio_isolate_lru(folio
)) {
402 if (folio_test_unevictable(folio
))
403 folio_putback_lru(folio
);
405 list_add(&folio
->lru
, &folio_list
);
408 folio_deactivate(folio
);
412 reclaim_pages(&folio_list
);
418 tlb_change_page_size(tlb
, PAGE_SIZE
);
419 start_pte
= pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, addr
, &ptl
);
422 flush_tlb_batched_pending(mm
);
423 arch_enter_lazy_mmu_mode();
424 for (; addr
< end
; pte
++, addr
+= PAGE_SIZE
) {
425 ptent
= ptep_get(pte
);
430 if (!pte_present(ptent
))
433 folio
= vm_normal_folio(vma
, addr
, ptent
);
434 if (!folio
|| folio_is_zone_device(folio
))
438 * Creating a THP page is expensive so split it only if we
439 * are sure it's worth. Split it if we are only owner.
441 if (folio_test_large(folio
)) {
444 if (folio_estimated_sharers(folio
) != 1)
446 if (pageout_anon_only_filter
&& !folio_test_anon(folio
))
448 if (!folio_trylock(folio
))
451 arch_leave_lazy_mmu_mode();
452 pte_unmap_unlock(start_pte
, ptl
);
454 err
= split_folio(folio
);
460 pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
463 arch_enter_lazy_mmu_mode();
470 * Do not interfere with other mappings of this folio and
473 if (!folio_test_lru(folio
) || folio_mapcount(folio
) != 1)
476 if (pageout_anon_only_filter
&& !folio_test_anon(folio
))
479 VM_BUG_ON_FOLIO(folio_test_large(folio
), folio
);
481 if (pte_young(ptent
)) {
482 ptent
= ptep_get_and_clear_full(mm
, addr
, pte
,
484 ptent
= pte_mkold(ptent
);
485 set_pte_at(mm
, addr
, pte
, ptent
);
486 tlb_remove_tlb_entry(tlb
, pte
, addr
);
490 * We are deactivating a folio for accelerating reclaiming.
491 * VM couldn't reclaim the folio unless we clear PG_young.
492 * As a side effect, it makes confuse idle-page tracking
493 * because they will miss recent referenced history.
495 folio_clear_referenced(folio
);
496 folio_test_clear_young(folio
);
497 if (folio_test_active(folio
))
498 folio_set_workingset(folio
);
500 if (folio_isolate_lru(folio
)) {
501 if (folio_test_unevictable(folio
))
502 folio_putback_lru(folio
);
504 list_add(&folio
->lru
, &folio_list
);
507 folio_deactivate(folio
);
511 arch_leave_lazy_mmu_mode();
512 pte_unmap_unlock(start_pte
, ptl
);
515 reclaim_pages(&folio_list
);
521 static const struct mm_walk_ops cold_walk_ops
= {
522 .pmd_entry
= madvise_cold_or_pageout_pte_range
,
523 .walk_lock
= PGWALK_RDLOCK
,
526 static void madvise_cold_page_range(struct mmu_gather
*tlb
,
527 struct vm_area_struct
*vma
,
528 unsigned long addr
, unsigned long end
)
530 struct madvise_walk_private walk_private
= {
535 tlb_start_vma(tlb
, vma
);
536 walk_page_range(vma
->vm_mm
, addr
, end
, &cold_walk_ops
, &walk_private
);
537 tlb_end_vma(tlb
, vma
);
540 static inline bool can_madv_lru_vma(struct vm_area_struct
*vma
)
542 return !(vma
->vm_flags
& (VM_LOCKED
|VM_PFNMAP
|VM_HUGETLB
));
545 static long madvise_cold(struct vm_area_struct
*vma
,
546 struct vm_area_struct
**prev
,
547 unsigned long start_addr
, unsigned long end_addr
)
549 struct mm_struct
*mm
= vma
->vm_mm
;
550 struct mmu_gather tlb
;
553 if (!can_madv_lru_vma(vma
))
557 tlb_gather_mmu(&tlb
, mm
);
558 madvise_cold_page_range(&tlb
, vma
, start_addr
, end_addr
);
559 tlb_finish_mmu(&tlb
);
564 static void madvise_pageout_page_range(struct mmu_gather
*tlb
,
565 struct vm_area_struct
*vma
,
566 unsigned long addr
, unsigned long end
)
568 struct madvise_walk_private walk_private
= {
573 tlb_start_vma(tlb
, vma
);
574 walk_page_range(vma
->vm_mm
, addr
, end
, &cold_walk_ops
, &walk_private
);
575 tlb_end_vma(tlb
, vma
);
578 static long madvise_pageout(struct vm_area_struct
*vma
,
579 struct vm_area_struct
**prev
,
580 unsigned long start_addr
, unsigned long end_addr
)
582 struct mm_struct
*mm
= vma
->vm_mm
;
583 struct mmu_gather tlb
;
586 if (!can_madv_lru_vma(vma
))
590 * If the VMA belongs to a private file mapping, there can be private
591 * dirty pages which can be paged out if even this process is neither
592 * owner nor write capable of the file. We allow private file mappings
593 * further to pageout dirty anon pages.
595 if (!vma_is_anonymous(vma
) && (!can_do_file_pageout(vma
) &&
596 (vma
->vm_flags
& VM_MAYSHARE
)))
600 tlb_gather_mmu(&tlb
, mm
);
601 madvise_pageout_page_range(&tlb
, vma
, start_addr
, end_addr
);
602 tlb_finish_mmu(&tlb
);
607 static int madvise_free_pte_range(pmd_t
*pmd
, unsigned long addr
,
608 unsigned long end
, struct mm_walk
*walk
)
611 struct mmu_gather
*tlb
= walk
->private;
612 struct mm_struct
*mm
= tlb
->mm
;
613 struct vm_area_struct
*vma
= walk
->vma
;
615 pte_t
*start_pte
, *pte
, ptent
;
620 next
= pmd_addr_end(addr
, end
);
621 if (pmd_trans_huge(*pmd
))
622 if (madvise_free_huge_pmd(tlb
, vma
, pmd
, addr
, next
))
625 tlb_change_page_size(tlb
, PAGE_SIZE
);
626 start_pte
= pte
= pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
629 flush_tlb_batched_pending(mm
);
630 arch_enter_lazy_mmu_mode();
631 for (; addr
!= end
; pte
++, addr
+= PAGE_SIZE
) {
632 ptent
= ptep_get(pte
);
637 * If the pte has swp_entry, just clear page table to
638 * prevent swap-in which is more expensive rather than
639 * (page allocation + zeroing).
641 if (!pte_present(ptent
)) {
644 entry
= pte_to_swp_entry(ptent
);
645 if (!non_swap_entry(entry
)) {
647 free_swap_and_cache(entry
);
648 pte_clear_not_present_full(mm
, addr
, pte
, tlb
->fullmm
);
649 } else if (is_hwpoison_entry(entry
) ||
650 is_poisoned_swp_entry(entry
)) {
651 pte_clear_not_present_full(mm
, addr
, pte
, tlb
->fullmm
);
656 folio
= vm_normal_folio(vma
, addr
, ptent
);
657 if (!folio
|| folio_is_zone_device(folio
))
661 * If pmd isn't transhuge but the folio is large and
662 * is owned by only this process, split it and
663 * deactivate all pages.
665 if (folio_test_large(folio
)) {
668 if (folio_estimated_sharers(folio
) != 1)
670 if (!folio_trylock(folio
))
673 arch_leave_lazy_mmu_mode();
674 pte_unmap_unlock(start_pte
, ptl
);
676 err
= split_folio(folio
);
682 pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
685 arch_enter_lazy_mmu_mode();
691 if (folio_test_swapcache(folio
) || folio_test_dirty(folio
)) {
692 if (!folio_trylock(folio
))
695 * If folio is shared with others, we mustn't clear
696 * the folio's dirty flag.
698 if (folio_mapcount(folio
) != 1) {
703 if (folio_test_swapcache(folio
) &&
704 !folio_free_swap(folio
)) {
709 folio_clear_dirty(folio
);
713 if (pte_young(ptent
) || pte_dirty(ptent
)) {
715 * Some of architecture(ex, PPC) don't update TLB
716 * with set_pte_at and tlb_remove_tlb_entry so for
717 * the portability, remap the pte with old|clean
718 * after pte clearing.
720 ptent
= ptep_get_and_clear_full(mm
, addr
, pte
,
723 ptent
= pte_mkold(ptent
);
724 ptent
= pte_mkclean(ptent
);
725 set_pte_at(mm
, addr
, pte
, ptent
);
726 tlb_remove_tlb_entry(tlb
, pte
, addr
);
728 folio_mark_lazyfree(folio
);
732 add_mm_counter(mm
, MM_SWAPENTS
, nr_swap
);
734 arch_leave_lazy_mmu_mode();
735 pte_unmap_unlock(start_pte
, ptl
);
742 static const struct mm_walk_ops madvise_free_walk_ops
= {
743 .pmd_entry
= madvise_free_pte_range
,
744 .walk_lock
= PGWALK_RDLOCK
,
747 static int madvise_free_single_vma(struct vm_area_struct
*vma
,
748 unsigned long start_addr
, unsigned long end_addr
)
750 struct mm_struct
*mm
= vma
->vm_mm
;
751 struct mmu_notifier_range range
;
752 struct mmu_gather tlb
;
754 /* MADV_FREE works for only anon vma at the moment */
755 if (!vma_is_anonymous(vma
))
758 range
.start
= max(vma
->vm_start
, start_addr
);
759 if (range
.start
>= vma
->vm_end
)
761 range
.end
= min(vma
->vm_end
, end_addr
);
762 if (range
.end
<= vma
->vm_start
)
764 mmu_notifier_range_init(&range
, MMU_NOTIFY_CLEAR
, 0, mm
,
765 range
.start
, range
.end
);
768 tlb_gather_mmu(&tlb
, mm
);
769 update_hiwater_rss(mm
);
771 mmu_notifier_invalidate_range_start(&range
);
772 tlb_start_vma(&tlb
, vma
);
773 walk_page_range(vma
->vm_mm
, range
.start
, range
.end
,
774 &madvise_free_walk_ops
, &tlb
);
775 tlb_end_vma(&tlb
, vma
);
776 mmu_notifier_invalidate_range_end(&range
);
777 tlb_finish_mmu(&tlb
);
783 * Application no longer needs these pages. If the pages are dirty,
784 * it's OK to just throw them away. The app will be more careful about
785 * data it wants to keep. Be sure to free swap resources too. The
786 * zap_page_range_single call sets things up for shrink_active_list to actually
787 * free these pages later if no one else has touched them in the meantime,
788 * although we could add these pages to a global reuse list for
789 * shrink_active_list to pick up before reclaiming other pages.
791 * NB: This interface discards data rather than pushes it out to swap,
792 * as some implementations do. This has performance implications for
793 * applications like large transactional databases which want to discard
794 * pages in anonymous maps after committing to backing store the data
795 * that was kept in them. There is no reason to write this data out to
796 * the swap area if the application is discarding it.
798 * An interface that causes the system to free clean pages and flush
799 * dirty pages is already available as msync(MS_INVALIDATE).
801 static long madvise_dontneed_single_vma(struct vm_area_struct
*vma
,
802 unsigned long start
, unsigned long end
)
804 zap_page_range_single(vma
, start
, end
- start
, NULL
);
808 static bool madvise_dontneed_free_valid_vma(struct vm_area_struct
*vma
,
813 if (!is_vm_hugetlb_page(vma
)) {
814 unsigned int forbidden
= VM_PFNMAP
;
816 if (behavior
!= MADV_DONTNEED_LOCKED
)
817 forbidden
|= VM_LOCKED
;
819 return !(vma
->vm_flags
& forbidden
);
822 if (behavior
!= MADV_DONTNEED
&& behavior
!= MADV_DONTNEED_LOCKED
)
824 if (start
& ~huge_page_mask(hstate_vma(vma
)))
828 * Madvise callers expect the length to be rounded up to PAGE_SIZE
829 * boundaries, and may be unaware that this VMA uses huge pages.
830 * Avoid unexpected data loss by rounding down the number of
833 *end
= ALIGN_DOWN(*end
, huge_page_size(hstate_vma(vma
)));
838 static long madvise_dontneed_free(struct vm_area_struct
*vma
,
839 struct vm_area_struct
**prev
,
840 unsigned long start
, unsigned long end
,
843 struct mm_struct
*mm
= vma
->vm_mm
;
846 if (!madvise_dontneed_free_valid_vma(vma
, start
, &end
, behavior
))
852 if (!userfaultfd_remove(vma
, start
, end
)) {
853 *prev
= NULL
; /* mmap_lock has been dropped, prev is stale */
856 vma
= vma_lookup(mm
, start
);
860 * Potential end adjustment for hugetlb vma is OK as
861 * the check below keeps end within vma.
863 if (!madvise_dontneed_free_valid_vma(vma
, start
, &end
,
866 if (end
> vma
->vm_end
) {
868 * Don't fail if end > vma->vm_end. If the old
869 * vma was split while the mmap_lock was
870 * released the effect of the concurrent
871 * operation may not cause madvise() to
872 * have an undefined result. There may be an
873 * adjacent next vma that we'll walk
874 * next. userfaultfd_remove() will generate an
875 * UFFD_EVENT_REMOVE repetition on the
876 * end-vma->vm_end range, but the manager can
877 * handle a repetition fine.
881 VM_WARN_ON(start
>= end
);
884 if (behavior
== MADV_DONTNEED
|| behavior
== MADV_DONTNEED_LOCKED
)
885 return madvise_dontneed_single_vma(vma
, start
, end
);
886 else if (behavior
== MADV_FREE
)
887 return madvise_free_single_vma(vma
, start
, end
);
892 static long madvise_populate(struct vm_area_struct
*vma
,
893 struct vm_area_struct
**prev
,
894 unsigned long start
, unsigned long end
,
897 const bool write
= behavior
== MADV_POPULATE_WRITE
;
898 struct mm_struct
*mm
= vma
->vm_mm
;
899 unsigned long tmp_end
;
905 while (start
< end
) {
907 * We might have temporarily dropped the lock. For example,
908 * our VMA might have been split.
910 if (!vma
|| start
>= vma
->vm_end
) {
911 vma
= vma_lookup(mm
, start
);
916 tmp_end
= min_t(unsigned long, end
, vma
->vm_end
);
917 /* Populate (prefault) page tables readable/writable. */
918 pages
= faultin_vma_page_range(vma
, start
, tmp_end
, write
,
930 case -EINVAL
: /* Incompatible mappings / permissions. */
934 case -EFAULT
: /* VM_FAULT_SIGBUS or VM_FAULT_SIGSEGV */
937 pr_warn_once("%s: unhandled return value: %ld\n",
944 start
+= pages
* PAGE_SIZE
;
950 * Application wants to free up the pages and associated backing store.
951 * This is effectively punching a hole into the middle of a file.
953 static long madvise_remove(struct vm_area_struct
*vma
,
954 struct vm_area_struct
**prev
,
955 unsigned long start
, unsigned long end
)
960 struct mm_struct
*mm
= vma
->vm_mm
;
962 *prev
= NULL
; /* tell sys_madvise we drop mmap_lock */
964 if (vma
->vm_flags
& VM_LOCKED
)
969 if (!f
|| !f
->f_mapping
|| !f
->f_mapping
->host
) {
973 if (!vma_is_shared_maywrite(vma
))
976 offset
= (loff_t
)(start
- vma
->vm_start
)
977 + ((loff_t
)vma
->vm_pgoff
<< PAGE_SHIFT
);
980 * Filesystem's fallocate may need to take i_rwsem. We need to
981 * explicitly grab a reference because the vma (and hence the
982 * vma's reference to the file) can go away as soon as we drop
986 if (userfaultfd_remove(vma
, start
, end
)) {
987 /* mmap_lock was not released by userfaultfd_remove() */
988 mmap_read_unlock(mm
);
990 error
= vfs_fallocate(f
,
991 FALLOC_FL_PUNCH_HOLE
| FALLOC_FL_KEEP_SIZE
,
992 offset
, end
- start
);
999 * Apply an madvise behavior to a region of a vma. madvise_update_vma
1000 * will handle splitting a vm area into separate areas, each area with its own
1003 static int madvise_vma_behavior(struct vm_area_struct
*vma
,
1004 struct vm_area_struct
**prev
,
1005 unsigned long start
, unsigned long end
,
1006 unsigned long behavior
)
1009 struct anon_vma_name
*anon_name
;
1010 unsigned long new_flags
= vma
->vm_flags
;
1014 return madvise_remove(vma
, prev
, start
, end
);
1016 return madvise_willneed(vma
, prev
, start
, end
);
1018 return madvise_cold(vma
, prev
, start
, end
);
1020 return madvise_pageout(vma
, prev
, start
, end
);
1023 case MADV_DONTNEED_LOCKED
:
1024 return madvise_dontneed_free(vma
, prev
, start
, end
, behavior
);
1025 case MADV_POPULATE_READ
:
1026 case MADV_POPULATE_WRITE
:
1027 return madvise_populate(vma
, prev
, start
, end
, behavior
);
1029 new_flags
= new_flags
& ~VM_RAND_READ
& ~VM_SEQ_READ
;
1031 case MADV_SEQUENTIAL
:
1032 new_flags
= (new_flags
& ~VM_RAND_READ
) | VM_SEQ_READ
;
1035 new_flags
= (new_flags
& ~VM_SEQ_READ
) | VM_RAND_READ
;
1038 new_flags
|= VM_DONTCOPY
;
1041 if (vma
->vm_flags
& VM_IO
)
1043 new_flags
&= ~VM_DONTCOPY
;
1045 case MADV_WIPEONFORK
:
1046 /* MADV_WIPEONFORK is only supported on anonymous memory. */
1047 if (vma
->vm_file
|| vma
->vm_flags
& VM_SHARED
)
1049 new_flags
|= VM_WIPEONFORK
;
1051 case MADV_KEEPONFORK
:
1052 new_flags
&= ~VM_WIPEONFORK
;
1055 new_flags
|= VM_DONTDUMP
;
1058 if (!is_vm_hugetlb_page(vma
) && new_flags
& VM_SPECIAL
)
1060 new_flags
&= ~VM_DONTDUMP
;
1062 case MADV_MERGEABLE
:
1063 case MADV_UNMERGEABLE
:
1064 error
= ksm_madvise(vma
, start
, end
, behavior
, &new_flags
);
1069 case MADV_NOHUGEPAGE
:
1070 error
= hugepage_madvise(vma
, &new_flags
, behavior
);
1075 return madvise_collapse(vma
, prev
, start
, end
);
1078 anon_name
= anon_vma_name(vma
);
1079 anon_vma_name_get(anon_name
);
1080 error
= madvise_update_vma(vma
, prev
, start
, end
, new_flags
,
1082 anon_vma_name_put(anon_name
);
1086 * madvise() returns EAGAIN if kernel resources, such as
1087 * slab, are temporarily unavailable.
1089 if (error
== -ENOMEM
)
1094 #ifdef CONFIG_MEMORY_FAILURE
1096 * Error injection support for memory error handling.
1098 static int madvise_inject_error(int behavior
,
1099 unsigned long start
, unsigned long end
)
1103 if (!capable(CAP_SYS_ADMIN
))
1107 for (; start
< end
; start
+= size
) {
1112 ret
= get_user_pages_fast(start
, 1, 0, &page
);
1115 pfn
= page_to_pfn(page
);
1118 * When soft offlining hugepages, after migrating the page
1119 * we dissolve it, therefore in the second loop "page" will
1120 * no longer be a compound page.
1122 size
= page_size(compound_head(page
));
1124 if (behavior
== MADV_SOFT_OFFLINE
) {
1125 pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
1127 ret
= soft_offline_page(pfn
, MF_COUNT_INCREASED
);
1129 pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
1131 ret
= memory_failure(pfn
, MF_COUNT_INCREASED
| MF_SW_SIMULATED
);
1132 if (ret
== -EOPNOTSUPP
)
1145 madvise_behavior_valid(int behavior
)
1151 case MADV_SEQUENTIAL
:
1156 case MADV_DONTNEED_LOCKED
:
1160 case MADV_POPULATE_READ
:
1161 case MADV_POPULATE_WRITE
:
1163 case MADV_MERGEABLE
:
1164 case MADV_UNMERGEABLE
:
1166 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
1168 case MADV_NOHUGEPAGE
:
1173 case MADV_WIPEONFORK
:
1174 case MADV_KEEPONFORK
:
1175 #ifdef CONFIG_MEMORY_FAILURE
1176 case MADV_SOFT_OFFLINE
:
1186 static bool process_madvise_behavior_valid(int behavior
)
1200 * Walk the vmas in range [start,end), and call the visit function on each one.
1201 * The visit function will get start and end parameters that cover the overlap
1202 * between the current vma and the original range. Any unmapped regions in the
1203 * original range will result in this function returning -ENOMEM while still
1204 * calling the visit function on all of the existing vmas in the range.
1205 * Must be called with the mmap_lock held for reading or writing.
1208 int madvise_walk_vmas(struct mm_struct
*mm
, unsigned long start
,
1209 unsigned long end
, unsigned long arg
,
1210 int (*visit
)(struct vm_area_struct
*vma
,
1211 struct vm_area_struct
**prev
, unsigned long start
,
1212 unsigned long end
, unsigned long arg
))
1214 struct vm_area_struct
*vma
;
1215 struct vm_area_struct
*prev
;
1217 int unmapped_error
= 0;
1220 * If the interval [start,end) covers some unmapped address
1221 * ranges, just ignore them, but return -ENOMEM at the end.
1222 * - different from the way of handling in mlock etc.
1224 vma
= find_vma_prev(mm
, start
, &prev
);
1225 if (vma
&& start
> vma
->vm_start
)
1231 /* Still start < end. */
1235 /* Here start < (end|vma->vm_end). */
1236 if (start
< vma
->vm_start
) {
1237 unmapped_error
= -ENOMEM
;
1238 start
= vma
->vm_start
;
1243 /* Here vma->vm_start <= start < (end|vma->vm_end) */
1248 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
1249 error
= visit(vma
, &prev
, start
, tmp
, arg
);
1253 if (prev
&& start
< prev
->vm_end
)
1254 start
= prev
->vm_end
;
1258 vma
= find_vma(mm
, prev
->vm_end
);
1259 else /* madvise_remove dropped mmap_lock */
1260 vma
= find_vma(mm
, start
);
1263 return unmapped_error
;
1266 #ifdef CONFIG_ANON_VMA_NAME
1267 static int madvise_vma_anon_name(struct vm_area_struct
*vma
,
1268 struct vm_area_struct
**prev
,
1269 unsigned long start
, unsigned long end
,
1270 unsigned long anon_name
)
1274 /* Only anonymous mappings can be named */
1275 if (vma
->vm_file
&& !vma_is_anon_shmem(vma
))
1278 error
= madvise_update_vma(vma
, prev
, start
, end
, vma
->vm_flags
,
1279 (struct anon_vma_name
*)anon_name
);
1282 * madvise() returns EAGAIN if kernel resources, such as
1283 * slab, are temporarily unavailable.
1285 if (error
== -ENOMEM
)
1290 int madvise_set_anon_name(struct mm_struct
*mm
, unsigned long start
,
1291 unsigned long len_in
, struct anon_vma_name
*anon_name
)
1296 if (start
& ~PAGE_MASK
)
1298 len
= (len_in
+ ~PAGE_MASK
) & PAGE_MASK
;
1300 /* Check to see whether len was rounded up from small -ve to zero */
1311 return madvise_walk_vmas(mm
, start
, end
, (unsigned long)anon_name
,
1312 madvise_vma_anon_name
);
1314 #endif /* CONFIG_ANON_VMA_NAME */
1316 * The madvise(2) system call.
1318 * Applications can use madvise() to advise the kernel how it should
1319 * handle paging I/O in this VM area. The idea is to help the kernel
1320 * use appropriate read-ahead and caching techniques. The information
1321 * provided is advisory only, and can be safely disregarded by the
1322 * kernel without affecting the correct operation of the application.
1325 * MADV_NORMAL - the default behavior is to read clusters. This
1326 * results in some read-ahead and read-behind.
1327 * MADV_RANDOM - the system should read the minimum amount of data
1328 * on any access, since it is unlikely that the appli-
1329 * cation will need more than what it asks for.
1330 * MADV_SEQUENTIAL - pages in the given range will probably be accessed
1331 * once, so they can be aggressively read ahead, and
1332 * can be freed soon after they are accessed.
1333 * MADV_WILLNEED - the application is notifying the system to read
1335 * MADV_DONTNEED - the application is finished with the given range,
1336 * so the kernel can free resources associated with it.
1337 * MADV_FREE - the application marks pages in the given range as lazy free,
1338 * where actual purges are postponed until memory pressure happens.
1339 * MADV_REMOVE - the application wants to free up the given range of
1340 * pages and associated backing store.
1341 * MADV_DONTFORK - omit this area from child's address space when forking:
1342 * typically, to avoid COWing pages pinned by get_user_pages().
1343 * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
1344 * MADV_WIPEONFORK - present the child process with zero-filled memory in this
1345 * range after a fork.
1346 * MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
1347 * MADV_HWPOISON - trigger memory error handler as if the given memory range
1348 * were corrupted by unrecoverable hardware memory failure.
1349 * MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
1350 * MADV_MERGEABLE - the application recommends that KSM try to merge pages in
1351 * this area with pages of identical content from other such areas.
1352 * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
1353 * MADV_HUGEPAGE - the application wants to back the given range by transparent
1354 * huge pages in the future. Existing pages might be coalesced and
1355 * new pages might be allocated as THP.
1356 * MADV_NOHUGEPAGE - mark the given range as not worth being backed by
1357 * transparent huge pages so the existing pages will not be
1358 * coalesced into THP and new pages will not be allocated as THP.
1359 * MADV_COLLAPSE - synchronously coalesce pages into new THP.
1360 * MADV_DONTDUMP - the application wants to prevent pages in the given range
1361 * from being included in its core dump.
1362 * MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
1363 * MADV_COLD - the application is not expected to use this memory soon,
1364 * deactivate pages in this range so that they can be reclaimed
1365 * easily if memory pressure happens.
1366 * MADV_PAGEOUT - the application is not expected to use this memory soon,
1367 * page out the pages in this range immediately.
1368 * MADV_POPULATE_READ - populate (prefault) page tables readable by
1369 * triggering read faults if required
1370 * MADV_POPULATE_WRITE - populate (prefault) page tables writable by
1371 * triggering write faults if required
1375 * -EINVAL - start + len < 0, start is not page-aligned,
1376 * "behavior" is not a valid value, or application
1377 * is attempting to release locked or shared pages,
1378 * or the specified address range includes file, Huge TLB,
1379 * MAP_SHARED or VMPFNMAP range.
1380 * -ENOMEM - addresses in the specified range are not currently
1381 * mapped, or are outside the AS of the process.
1382 * -EIO - an I/O error occurred while paging in data.
1383 * -EBADF - map exists, but area maps something that isn't a file.
1384 * -EAGAIN - a kernel resource was temporarily unavailable.
1386 int do_madvise(struct mm_struct
*mm
, unsigned long start
, size_t len_in
, int behavior
)
1392 struct blk_plug plug
;
1394 if (!madvise_behavior_valid(behavior
))
1397 if (!PAGE_ALIGNED(start
))
1399 len
= PAGE_ALIGN(len_in
);
1401 /* Check to see whether len was rounded up from small -ve to zero */
1412 #ifdef CONFIG_MEMORY_FAILURE
1413 if (behavior
== MADV_HWPOISON
|| behavior
== MADV_SOFT_OFFLINE
)
1414 return madvise_inject_error(behavior
, start
, start
+ len_in
);
1417 write
= madvise_need_mmap_write(behavior
);
1419 if (mmap_write_lock_killable(mm
))
1425 start
= untagged_addr_remote(mm
, start
);
1428 blk_start_plug(&plug
);
1429 error
= madvise_walk_vmas(mm
, start
, end
, behavior
,
1430 madvise_vma_behavior
);
1431 blk_finish_plug(&plug
);
1433 mmap_write_unlock(mm
);
1435 mmap_read_unlock(mm
);
1440 SYSCALL_DEFINE3(madvise
, unsigned long, start
, size_t, len_in
, int, behavior
)
1442 return do_madvise(current
->mm
, start
, len_in
, behavior
);
1445 SYSCALL_DEFINE5(process_madvise
, int, pidfd
, const struct iovec __user
*, vec
,
1446 size_t, vlen
, int, behavior
, unsigned int, flags
)
1449 struct iovec iovstack
[UIO_FASTIOV
];
1450 struct iovec
*iov
= iovstack
;
1451 struct iov_iter iter
;
1452 struct task_struct
*task
;
1453 struct mm_struct
*mm
;
1455 unsigned int f_flags
;
1462 ret
= import_iovec(ITER_DEST
, vec
, vlen
, ARRAY_SIZE(iovstack
), &iov
, &iter
);
1466 task
= pidfd_get_task(pidfd
, &f_flags
);
1468 ret
= PTR_ERR(task
);
1472 if (!process_madvise_behavior_valid(behavior
)) {
1477 /* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */
1478 mm
= mm_access(task
, PTRACE_MODE_READ_FSCREDS
);
1479 if (IS_ERR_OR_NULL(mm
)) {
1480 ret
= IS_ERR(mm
) ? PTR_ERR(mm
) : -ESRCH
;
1485 * Require CAP_SYS_NICE for influencing process performance. Note that
1486 * only non-destructive hints are currently supported.
1488 if (!capable(CAP_SYS_NICE
)) {
1493 total_len
= iov_iter_count(&iter
);
1495 while (iov_iter_count(&iter
)) {
1496 ret
= do_madvise(mm
, (unsigned long)iter_iov_addr(&iter
),
1497 iter_iov_len(&iter
), behavior
);
1500 iov_iter_advance(&iter
, iter_iov_len(&iter
));
1503 ret
= (total_len
- iov_iter_count(&iter
)) ? : ret
;
1508 put_task_struct(task
);