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4 * Copyright (C) 1999 Linus Torvalds
5 * Copyright (C) 2002 Christoph Hellwig
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/userfaultfd_k.h>
14 #include <linux/hugetlb.h>
15 #include <linux/falloc.h>
16 #include <linux/sched.h>
17 #include <linux/ksm.h>
19 #include <linux/file.h>
20 #include <linux/blkdev.h>
21 #include <linux/backing-dev.h>
22 #include <linux/swap.h>
23 #include <linux/swapops.h>
24 #include <linux/shmem_fs.h>
25 #include <linux/mmu_notifier.h>
32 * Any behaviour which results in changes to the vma->vm_flags needs to
33 * take mmap_sem for writing. Others, which simply traverse vmas, need
34 * to only take it for reading.
36 static int madvise_need_mmap_write(int behavior
)
45 /* be safe, default to 1. list exceptions explicitly */
51 * We can potentially split a vm area into separate
52 * areas, each area with its own behavior.
54 static long madvise_behavior(struct vm_area_struct
*vma
,
55 struct vm_area_struct
**prev
,
56 unsigned long start
, unsigned long end
, int behavior
)
58 struct mm_struct
*mm
= vma
->vm_mm
;
61 unsigned long new_flags
= vma
->vm_flags
;
65 new_flags
= new_flags
& ~VM_RAND_READ
& ~VM_SEQ_READ
;
68 new_flags
= (new_flags
& ~VM_RAND_READ
) | VM_SEQ_READ
;
71 new_flags
= (new_flags
& ~VM_SEQ_READ
) | VM_RAND_READ
;
74 new_flags
|= VM_DONTCOPY
;
77 if (vma
->vm_flags
& VM_IO
) {
81 new_flags
&= ~VM_DONTCOPY
;
84 new_flags
|= VM_DONTDUMP
;
87 if (new_flags
& VM_SPECIAL
) {
91 new_flags
&= ~VM_DONTDUMP
;
94 case MADV_UNMERGEABLE
:
95 error
= ksm_madvise(vma
, start
, end
, behavior
, &new_flags
);
98 * madvise() returns EAGAIN if kernel resources, such as
99 * slab, are temporarily unavailable.
101 if (error
== -ENOMEM
)
107 case MADV_NOHUGEPAGE
:
108 error
= hugepage_madvise(vma
, &new_flags
, behavior
);
111 * madvise() returns EAGAIN if kernel resources, such as
112 * slab, are temporarily unavailable.
114 if (error
== -ENOMEM
)
121 if (new_flags
== vma
->vm_flags
) {
126 pgoff
= vma
->vm_pgoff
+ ((start
- vma
->vm_start
) >> PAGE_SHIFT
);
127 *prev
= vma_merge(mm
, *prev
, start
, end
, new_flags
, vma
->anon_vma
,
128 vma
->vm_file
, pgoff
, vma_policy(vma
),
129 vma
->vm_userfaultfd_ctx
);
137 if (start
!= vma
->vm_start
) {
138 if (unlikely(mm
->map_count
>= sysctl_max_map_count
)) {
142 error
= __split_vma(mm
, vma
, start
, 1);
145 * madvise() returns EAGAIN if kernel resources, such as
146 * slab, are temporarily unavailable.
148 if (error
== -ENOMEM
)
154 if (end
!= vma
->vm_end
) {
155 if (unlikely(mm
->map_count
>= sysctl_max_map_count
)) {
159 error
= __split_vma(mm
, vma
, end
, 0);
162 * madvise() returns EAGAIN if kernel resources, such as
163 * slab, are temporarily unavailable.
165 if (error
== -ENOMEM
)
173 * vm_flags is protected by the mmap_sem held in write mode.
175 vma
->vm_flags
= new_flags
;
181 static int swapin_walk_pmd_entry(pmd_t
*pmd
, unsigned long start
,
182 unsigned long end
, struct mm_walk
*walk
)
185 struct vm_area_struct
*vma
= walk
->private;
188 if (pmd_none_or_trans_huge_or_clear_bad(pmd
))
191 for (index
= start
; index
!= end
; index
+= PAGE_SIZE
) {
197 orig_pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, start
, &ptl
);
198 pte
= *(orig_pte
+ ((index
- start
) / PAGE_SIZE
));
199 pte_unmap_unlock(orig_pte
, ptl
);
201 if (pte_present(pte
) || pte_none(pte
))
203 entry
= pte_to_swp_entry(pte
);
204 if (unlikely(non_swap_entry(entry
)))
207 page
= read_swap_cache_async(entry
, GFP_HIGHUSER_MOVABLE
,
216 static void force_swapin_readahead(struct vm_area_struct
*vma
,
217 unsigned long start
, unsigned long end
)
219 struct mm_walk walk
= {
221 .pmd_entry
= swapin_walk_pmd_entry
,
225 walk_page_range(start
, end
, &walk
);
227 lru_add_drain(); /* Push any new pages onto the LRU now */
230 static void force_shm_swapin_readahead(struct vm_area_struct
*vma
,
231 unsigned long start
, unsigned long end
,
232 struct address_space
*mapping
)
238 for (; start
< end
; start
+= PAGE_SIZE
) {
239 index
= ((start
- vma
->vm_start
) >> PAGE_SHIFT
) + vma
->vm_pgoff
;
241 page
= find_get_entry(mapping
, index
);
242 if (!radix_tree_exceptional_entry(page
)) {
247 swap
= radix_to_swp_entry(page
);
248 page
= read_swap_cache_async(swap
, GFP_HIGHUSER_MOVABLE
,
254 lru_add_drain(); /* Push any new pages onto the LRU now */
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 file
*file
= vma
->vm_file
;
270 force_swapin_readahead(vma
, start
, end
);
274 if (shmem_mapping(file
->f_mapping
)) {
276 force_shm_swapin_readahead(vma
, start
, end
,
285 if (IS_DAX(file_inode(file
))) {
286 /* no bad return value, but ignore advice */
291 start
= ((start
- vma
->vm_start
) >> PAGE_SHIFT
) + vma
->vm_pgoff
;
292 if (end
> vma
->vm_end
)
294 end
= ((end
- vma
->vm_start
) >> PAGE_SHIFT
) + vma
->vm_pgoff
;
296 force_page_cache_readahead(file
->f_mapping
, file
, start
, end
- start
);
300 static int madvise_free_pte_range(pmd_t
*pmd
, unsigned long addr
,
301 unsigned long end
, struct mm_walk
*walk
)
304 struct mmu_gather
*tlb
= walk
->private;
305 struct mm_struct
*mm
= tlb
->mm
;
306 struct vm_area_struct
*vma
= walk
->vma
;
308 pte_t
*orig_pte
, *pte
, ptent
;
313 next
= pmd_addr_end(addr
, end
);
314 if (pmd_trans_huge(*pmd
))
315 if (madvise_free_huge_pmd(tlb
, vma
, pmd
, addr
, next
))
318 if (pmd_trans_unstable(pmd
))
321 tlb_remove_check_page_size_change(tlb
, PAGE_SIZE
);
322 orig_pte
= pte
= pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
323 arch_enter_lazy_mmu_mode();
324 for (; addr
!= end
; pte
++, addr
+= PAGE_SIZE
) {
330 * If the pte has swp_entry, just clear page table to
331 * prevent swap-in which is more expensive rather than
332 * (page allocation + zeroing).
334 if (!pte_present(ptent
)) {
337 entry
= pte_to_swp_entry(ptent
);
338 if (non_swap_entry(entry
))
341 free_swap_and_cache(entry
);
342 pte_clear_not_present_full(mm
, addr
, pte
, tlb
->fullmm
);
346 page
= vm_normal_page(vma
, addr
, ptent
);
351 * If pmd isn't transhuge but the page is THP and
352 * is owned by only this process, split it and
353 * deactivate all pages.
355 if (PageTransCompound(page
)) {
356 if (page_mapcount(page
) != 1)
359 if (!trylock_page(page
)) {
363 pte_unmap_unlock(orig_pte
, ptl
);
364 if (split_huge_page(page
)) {
367 pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
372 pte
= pte_offset_map_lock(mm
, pmd
, addr
, &ptl
);
378 VM_BUG_ON_PAGE(PageTransCompound(page
), page
);
380 if (PageSwapCache(page
) || PageDirty(page
)) {
381 if (!trylock_page(page
))
384 * If page is shared with others, we couldn't clear
385 * PG_dirty of the page.
387 if (page_mapcount(page
) != 1) {
392 if (PageSwapCache(page
) && !try_to_free_swap(page
)) {
397 ClearPageDirty(page
);
401 if (pte_young(ptent
) || pte_dirty(ptent
)) {
403 * Some of architecture(ex, PPC) don't update TLB
404 * with set_pte_at and tlb_remove_tlb_entry so for
405 * the portability, remap the pte with old|clean
406 * after pte clearing.
408 ptent
= ptep_get_and_clear_full(mm
, addr
, pte
,
411 ptent
= pte_mkold(ptent
);
412 ptent
= pte_mkclean(ptent
);
413 set_pte_at(mm
, addr
, pte
, ptent
);
414 if (PageActive(page
))
415 deactivate_page(page
);
416 tlb_remove_tlb_entry(tlb
, pte
, addr
);
421 if (current
->mm
== mm
)
424 add_mm_counter(mm
, MM_SWAPENTS
, nr_swap
);
426 arch_leave_lazy_mmu_mode();
427 pte_unmap_unlock(orig_pte
, ptl
);
433 static void madvise_free_page_range(struct mmu_gather
*tlb
,
434 struct vm_area_struct
*vma
,
435 unsigned long addr
, unsigned long end
)
437 struct mm_walk free_walk
= {
438 .pmd_entry
= madvise_free_pte_range
,
443 tlb_start_vma(tlb
, vma
);
444 walk_page_range(addr
, end
, &free_walk
);
445 tlb_end_vma(tlb
, vma
);
448 static int madvise_free_single_vma(struct vm_area_struct
*vma
,
449 unsigned long start_addr
, unsigned long end_addr
)
451 unsigned long start
, end
;
452 struct mm_struct
*mm
= vma
->vm_mm
;
453 struct mmu_gather tlb
;
455 if (vma
->vm_flags
& (VM_LOCKED
|VM_HUGETLB
|VM_PFNMAP
))
458 /* MADV_FREE works for only anon vma at the moment */
459 if (!vma_is_anonymous(vma
))
462 start
= max(vma
->vm_start
, start_addr
);
463 if (start
>= vma
->vm_end
)
465 end
= min(vma
->vm_end
, end_addr
);
466 if (end
<= vma
->vm_start
)
470 tlb_gather_mmu(&tlb
, mm
, start
, end
);
471 update_hiwater_rss(mm
);
473 mmu_notifier_invalidate_range_start(mm
, start
, end
);
474 madvise_free_page_range(&tlb
, vma
, start
, end
);
475 mmu_notifier_invalidate_range_end(mm
, start
, end
);
476 tlb_finish_mmu(&tlb
, start
, end
);
481 static long madvise_free(struct vm_area_struct
*vma
,
482 struct vm_area_struct
**prev
,
483 unsigned long start
, unsigned long end
)
486 return madvise_free_single_vma(vma
, start
, end
);
490 * Application no longer needs these pages. If the pages are dirty,
491 * it's OK to just throw them away. The app will be more careful about
492 * data it wants to keep. Be sure to free swap resources too. The
493 * zap_page_range call sets things up for shrink_active_list to actually free
494 * these pages later if no one else has touched them in the meantime,
495 * although we could add these pages to a global reuse list for
496 * shrink_active_list to pick up before reclaiming other pages.
498 * NB: This interface discards data rather than pushes it out to swap,
499 * as some implementations do. This has performance implications for
500 * applications like large transactional databases which want to discard
501 * pages in anonymous maps after committing to backing store the data
502 * that was kept in them. There is no reason to write this data out to
503 * the swap area if the application is discarding it.
505 * An interface that causes the system to free clean pages and flush
506 * dirty pages is already available as msync(MS_INVALIDATE).
508 static long madvise_dontneed(struct vm_area_struct
*vma
,
509 struct vm_area_struct
**prev
,
510 unsigned long start
, unsigned long end
)
513 if (!can_madv_dontneed_vma(vma
))
516 userfaultfd_remove(vma
, prev
, start
, end
);
517 zap_page_range(vma
, start
, end
- start
);
522 * Application wants to free up the pages and associated backing store.
523 * This is effectively punching a hole into the middle of a file.
525 static long madvise_remove(struct vm_area_struct
*vma
,
526 struct vm_area_struct
**prev
,
527 unsigned long start
, unsigned long end
)
533 *prev
= NULL
; /* tell sys_madvise we drop mmap_sem */
535 if (vma
->vm_flags
& VM_LOCKED
)
540 if (!f
|| !f
->f_mapping
|| !f
->f_mapping
->host
) {
544 if ((vma
->vm_flags
& (VM_SHARED
|VM_WRITE
)) != (VM_SHARED
|VM_WRITE
))
547 offset
= (loff_t
)(start
- vma
->vm_start
)
548 + ((loff_t
)vma
->vm_pgoff
<< PAGE_SHIFT
);
551 * Filesystem's fallocate may need to take i_mutex. We need to
552 * explicitly grab a reference because the vma (and hence the
553 * vma's reference to the file) can go away as soon as we drop
557 userfaultfd_remove(vma
, prev
, start
, end
);
558 up_read(¤t
->mm
->mmap_sem
);
559 error
= vfs_fallocate(f
,
560 FALLOC_FL_PUNCH_HOLE
| FALLOC_FL_KEEP_SIZE
,
561 offset
, end
- start
);
563 down_read(¤t
->mm
->mmap_sem
);
567 #ifdef CONFIG_MEMORY_FAILURE
569 * Error injection support for memory error handling.
571 static int madvise_hwpoison(int bhv
, unsigned long start
, unsigned long end
)
574 if (!capable(CAP_SYS_ADMIN
))
576 for (; start
< end
; start
+= PAGE_SIZE
<<
577 compound_order(compound_head(p
))) {
580 ret
= get_user_pages_fast(start
, 1, 0, &p
);
584 if (PageHWPoison(p
)) {
588 if (bhv
== MADV_SOFT_OFFLINE
) {
589 pr_info("Soft offlining page %#lx at %#lx\n",
590 page_to_pfn(p
), start
);
591 ret
= soft_offline_page(p
, MF_COUNT_INCREASED
);
596 pr_info("Injecting memory failure for page %#lx at %#lx\n",
597 page_to_pfn(p
), start
);
598 ret
= memory_failure(page_to_pfn(p
), 0, MF_COUNT_INCREASED
);
607 madvise_vma(struct vm_area_struct
*vma
, struct vm_area_struct
**prev
,
608 unsigned long start
, unsigned long end
, int behavior
)
612 return madvise_remove(vma
, prev
, start
, end
);
614 return madvise_willneed(vma
, prev
, start
, end
);
617 * XXX: In this implementation, MADV_FREE works like
618 * MADV_DONTNEED on swapless system or full swap.
620 if (get_nr_swap_pages() > 0)
621 return madvise_free(vma
, prev
, start
, end
);
624 return madvise_dontneed(vma
, prev
, start
, end
);
626 return madvise_behavior(vma
, prev
, start
, end
, behavior
);
631 madvise_behavior_valid(int behavior
)
637 case MADV_SEQUENTIAL
:
645 case MADV_UNMERGEABLE
:
647 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
649 case MADV_NOHUGEPAGE
:
661 * The madvise(2) system call.
663 * Applications can use madvise() to advise the kernel how it should
664 * handle paging I/O in this VM area. The idea is to help the kernel
665 * use appropriate read-ahead and caching techniques. The information
666 * provided is advisory only, and can be safely disregarded by the
667 * kernel without affecting the correct operation of the application.
670 * MADV_NORMAL - the default behavior is to read clusters. This
671 * results in some read-ahead and read-behind.
672 * MADV_RANDOM - the system should read the minimum amount of data
673 * on any access, since it is unlikely that the appli-
674 * cation will need more than what it asks for.
675 * MADV_SEQUENTIAL - pages in the given range will probably be accessed
676 * once, so they can be aggressively read ahead, and
677 * can be freed soon after they are accessed.
678 * MADV_WILLNEED - the application is notifying the system to read
680 * MADV_DONTNEED - the application is finished with the given range,
681 * so the kernel can free resources associated with it.
682 * MADV_FREE - the application marks pages in the given range as lazy free,
683 * where actual purges are postponed until memory pressure happens.
684 * MADV_REMOVE - the application wants to free up the given range of
685 * pages and associated backing store.
686 * MADV_DONTFORK - omit this area from child's address space when forking:
687 * typically, to avoid COWing pages pinned by get_user_pages().
688 * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
689 * MADV_HWPOISON - trigger memory error handler as if the given memory range
690 * were corrupted by unrecoverable hardware memory failure.
691 * MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
692 * MADV_MERGEABLE - the application recommends that KSM try to merge pages in
693 * this area with pages of identical content from other such areas.
694 * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
695 * MADV_HUGEPAGE - the application wants to back the given range by transparent
696 * huge pages in the future. Existing pages might be coalesced and
697 * new pages might be allocated as THP.
698 * MADV_NOHUGEPAGE - mark the given range as not worth being backed by
699 * transparent huge pages so the existing pages will not be
700 * coalesced into THP and new pages will not be allocated as THP.
701 * MADV_DONTDUMP - the application wants to prevent pages in the given range
702 * from being included in its core dump.
703 * MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
707 * -EINVAL - start + len < 0, start is not page-aligned,
708 * "behavior" is not a valid value, or application
709 * is attempting to release locked or shared pages.
710 * -ENOMEM - addresses in the specified range are not currently
711 * mapped, or are outside the AS of the process.
712 * -EIO - an I/O error occurred while paging in data.
713 * -EBADF - map exists, but area maps something that isn't a file.
714 * -EAGAIN - a kernel resource was temporarily unavailable.
716 SYSCALL_DEFINE3(madvise
, unsigned long, start
, size_t, len_in
, int, behavior
)
718 unsigned long end
, tmp
;
719 struct vm_area_struct
*vma
, *prev
;
720 int unmapped_error
= 0;
724 struct blk_plug plug
;
726 #ifdef CONFIG_MEMORY_FAILURE
727 if (behavior
== MADV_HWPOISON
|| behavior
== MADV_SOFT_OFFLINE
)
728 return madvise_hwpoison(behavior
, start
, start
+len_in
);
730 if (!madvise_behavior_valid(behavior
))
733 if (start
& ~PAGE_MASK
)
735 len
= (len_in
+ ~PAGE_MASK
) & PAGE_MASK
;
737 /* Check to see whether len was rounded up from small -ve to zero */
749 write
= madvise_need_mmap_write(behavior
);
751 if (down_write_killable(¤t
->mm
->mmap_sem
))
754 down_read(¤t
->mm
->mmap_sem
);
758 * If the interval [start,end) covers some unmapped address
759 * ranges, just ignore them, but return -ENOMEM at the end.
760 * - different from the way of handling in mlock etc.
762 vma
= find_vma_prev(current
->mm
, start
, &prev
);
763 if (vma
&& start
> vma
->vm_start
)
766 blk_start_plug(&plug
);
768 /* Still start < end. */
773 /* Here start < (end|vma->vm_end). */
774 if (start
< vma
->vm_start
) {
775 unmapped_error
= -ENOMEM
;
776 start
= vma
->vm_start
;
781 /* Here vma->vm_start <= start < (end|vma->vm_end) */
786 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
787 error
= madvise_vma(vma
, &prev
, start
, tmp
, behavior
);
791 if (prev
&& start
< prev
->vm_end
)
792 start
= prev
->vm_end
;
793 error
= unmapped_error
;
798 else /* madvise_remove dropped mmap_sem */
799 vma
= find_vma(current
->mm
, start
);
802 blk_finish_plug(&plug
);
804 up_write(¤t
->mm
->mmap_sem
);
806 up_read(¤t
->mm
->mmap_sem
);