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/fadvise.h>
18 #include <linux/sched.h>
19 #include <linux/ksm.h>
21 #include <linux/file.h>
22 #include <linux/blkdev.h>
23 #include <linux/backing-dev.h>
24 #include <linux/pagewalk.h>
25 #include <linux/swap.h>
26 #include <linux/swapops.h>
27 #include <linux/shmem_fs.h>
28 #include <linux/mmu_notifier.h>
35 * Any behaviour which results in changes to the vma->vm_flags needs to
36 * take mmap_sem for writing. Others, which simply traverse vmas, need
37 * to only take it for reading.
39 static int madvise_need_mmap_write(int behavior)
48 /* be safe, default to 1. list exceptions explicitly */
54 * We can potentially split a vm area into separate
55 * areas, each area with its own behavior.
57 static long madvise_behavior(struct vm_area_struct *vma,
58 struct vm_area_struct **prev,
59 unsigned long start, unsigned long end, int behavior)
61 struct mm_struct *mm = vma->vm_mm;
64 unsigned long new_flags = vma->vm_flags;
68 new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ;
71 new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ;
74 new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ;
77 new_flags |= VM_DONTCOPY;
80 if (vma->vm_flags & VM_IO) {
84 new_flags &= ~VM_DONTCOPY;
87 /* MADV_WIPEONFORK is only supported on anonymous memory. */
88 if (vma->vm_file || vma->vm_flags & VM_SHARED) {
92 new_flags |= VM_WIPEONFORK;
95 new_flags &= ~VM_WIPEONFORK;
98 new_flags |= VM_DONTDUMP;
101 if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL) {
105 new_flags &= ~VM_DONTDUMP;
108 case MADV_UNMERGEABLE:
109 error = ksm_madvise(vma, start, end, behavior, &new_flags);
112 * madvise() returns EAGAIN if kernel resources, such as
113 * slab, are temporarily unavailable.
115 if (error == -ENOMEM)
121 case MADV_NOHUGEPAGE:
122 error = hugepage_madvise(vma, &new_flags, behavior);
125 * madvise() returns EAGAIN if kernel resources, such as
126 * slab, are temporarily unavailable.
128 if (error == -ENOMEM)
135 if (new_flags == vma->vm_flags) {
140 pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
141 *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
142 vma->vm_file, pgoff, vma_policy(vma),
143 vma->vm_userfaultfd_ctx);
151 if (start != vma->vm_start) {
152 if (unlikely(mm->map_count >= sysctl_max_map_count)) {
156 error = __split_vma(mm, vma, start, 1);
159 * madvise() returns EAGAIN if kernel resources, such as
160 * slab, are temporarily unavailable.
162 if (error == -ENOMEM)
168 if (end != vma->vm_end) {
169 if (unlikely(mm->map_count >= sysctl_max_map_count)) {
173 error = __split_vma(mm, vma, end, 0);
176 * madvise() returns EAGAIN if kernel resources, such as
177 * slab, are temporarily unavailable.
179 if (error == -ENOMEM)
187 * vm_flags is protected by the mmap_sem held in write mode.
189 vma->vm_flags = new_flags;
195 static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start,
196 unsigned long end, struct mm_walk *walk)
199 struct vm_area_struct *vma = walk->private;
202 if (pmd_none_or_trans_huge_or_clear_bad(pmd))
205 for (index = start; index != end; index += PAGE_SIZE) {
211 orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl);
212 pte = *(orig_pte + ((index - start) / PAGE_SIZE));
213 pte_unmap_unlock(orig_pte, ptl);
215 if (pte_present(pte) || pte_none(pte))
217 entry = pte_to_swp_entry(pte);
218 if (unlikely(non_swap_entry(entry)))
221 page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE,
230 static const struct mm_walk_ops swapin_walk_ops = {
231 .pmd_entry = swapin_walk_pmd_entry,
234 static void force_shm_swapin_readahead(struct vm_area_struct *vma,
235 unsigned long start, unsigned long end,
236 struct address_space *mapping)
242 for (; start < end; start += PAGE_SIZE) {
243 index = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;
245 page = find_get_entry(mapping, index);
246 if (!xa_is_value(page)) {
251 swap = radix_to_swp_entry(page);
252 page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE,
258 lru_add_drain(); /* Push any new pages onto the LRU now */
260 #endif /* CONFIG_SWAP */
263 * Schedule all required I/O operations. Do not wait for completion.
265 static long madvise_willneed(struct vm_area_struct *vma,
266 struct vm_area_struct **prev,
267 unsigned long start, unsigned long end)
269 struct file *file = vma->vm_file;
275 walk_page_range(vma->vm_mm, start, end, &swapin_walk_ops, vma);
276 lru_add_drain(); /* Push any new pages onto the LRU now */
280 if (shmem_mapping(file->f_mapping)) {
281 force_shm_swapin_readahead(vma, start, end,
290 if (IS_DAX(file_inode(file))) {
291 /* no bad return value, but ignore advice */
296 * Filesystem's fadvise may need to take various locks. We need to
297 * explicitly grab a reference because the vma (and hence the
298 * vma's reference to the file) can go away as soon as we drop
301 *prev = NULL; /* tell sys_madvise we drop mmap_sem */
303 up_read(¤t->mm->mmap_sem);
304 offset = (loff_t)(start - vma->vm_start)
305 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
306 vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED);
308 down_read(¤t->mm->mmap_sem);
312 static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
313 unsigned long end, struct mm_walk *walk)
316 struct mmu_gather *tlb = walk->private;
317 struct mm_struct *mm = tlb->mm;
318 struct vm_area_struct *vma = walk->vma;
320 pte_t *orig_pte, *pte, ptent;
325 next = pmd_addr_end(addr, end);
326 if (pmd_trans_huge(*pmd))
327 if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next))
330 if (pmd_trans_unstable(pmd))
333 tlb_change_page_size(tlb, PAGE_SIZE);
334 orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
335 flush_tlb_batched_pending(mm);
336 arch_enter_lazy_mmu_mode();
337 for (; addr != end; pte++, addr += PAGE_SIZE) {
343 * If the pte has swp_entry, just clear page table to
344 * prevent swap-in which is more expensive rather than
345 * (page allocation + zeroing).
347 if (!pte_present(ptent)) {
350 entry = pte_to_swp_entry(ptent);
351 if (non_swap_entry(entry))
354 free_swap_and_cache(entry);
355 pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
359 page = vm_normal_page(vma, addr, ptent);
364 * If pmd isn't transhuge but the page is THP and
365 * is owned by only this process, split it and
366 * deactivate all pages.
368 if (PageTransCompound(page)) {
369 if (page_mapcount(page) != 1)
372 if (!trylock_page(page)) {
376 pte_unmap_unlock(orig_pte, ptl);
377 if (split_huge_page(page)) {
380 pte_offset_map_lock(mm, pmd, addr, &ptl);
385 pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
391 VM_BUG_ON_PAGE(PageTransCompound(page), page);
393 if (PageSwapCache(page) || PageDirty(page)) {
394 if (!trylock_page(page))
397 * If page is shared with others, we couldn't clear
398 * PG_dirty of the page.
400 if (page_mapcount(page) != 1) {
405 if (PageSwapCache(page) && !try_to_free_swap(page)) {
410 ClearPageDirty(page);
414 if (pte_young(ptent) || pte_dirty(ptent)) {
416 * Some of architecture(ex, PPC) don't update TLB
417 * with set_pte_at and tlb_remove_tlb_entry so for
418 * the portability, remap the pte with old|clean
419 * after pte clearing.
421 ptent = ptep_get_and_clear_full(mm, addr, pte,
424 ptent = pte_mkold(ptent);
425 ptent = pte_mkclean(ptent);
426 set_pte_at(mm, addr, pte, ptent);
427 tlb_remove_tlb_entry(tlb, pte, addr);
429 mark_page_lazyfree(page);
433 if (current->mm == mm)
436 add_mm_counter(mm, MM_SWAPENTS, nr_swap);
438 arch_leave_lazy_mmu_mode();
439 pte_unmap_unlock(orig_pte, ptl);
445 static const struct mm_walk_ops madvise_free_walk_ops = {
446 .pmd_entry = madvise_free_pte_range,
449 static int madvise_free_single_vma(struct vm_area_struct *vma,
450 unsigned long start_addr, unsigned long end_addr)
452 struct mm_struct *mm = vma->vm_mm;
453 struct mmu_notifier_range range;
454 struct mmu_gather tlb;
456 /* MADV_FREE works for only anon vma at the moment */
457 if (!vma_is_anonymous(vma))
460 range.start = max(vma->vm_start, start_addr);
461 if (range.start >= vma->vm_end)
463 range.end = min(vma->vm_end, end_addr);
464 if (range.end <= vma->vm_start)
466 mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm,
467 range.start, range.end);
470 tlb_gather_mmu(&tlb, mm, range.start, range.end);
471 update_hiwater_rss(mm);
473 mmu_notifier_invalidate_range_start(&range);
474 tlb_start_vma(&tlb, vma);
475 walk_page_range(vma->vm_mm, range.start, range.end,
476 &madvise_free_walk_ops, &tlb);
477 tlb_end_vma(&tlb, vma);
478 mmu_notifier_invalidate_range_end(&range);
479 tlb_finish_mmu(&tlb, range.start, range.end);
485 * Application no longer needs these pages. If the pages are dirty,
486 * it's OK to just throw them away. The app will be more careful about
487 * data it wants to keep. Be sure to free swap resources too. The
488 * zap_page_range call sets things up for shrink_active_list to actually free
489 * these pages later if no one else has touched them in the meantime,
490 * although we could add these pages to a global reuse list for
491 * shrink_active_list to pick up before reclaiming other pages.
493 * NB: This interface discards data rather than pushes it out to swap,
494 * as some implementations do. This has performance implications for
495 * applications like large transactional databases which want to discard
496 * pages in anonymous maps after committing to backing store the data
497 * that was kept in them. There is no reason to write this data out to
498 * the swap area if the application is discarding it.
500 * An interface that causes the system to free clean pages and flush
501 * dirty pages is already available as msync(MS_INVALIDATE).
503 static long madvise_dontneed_single_vma(struct vm_area_struct *vma,
504 unsigned long start, unsigned long end)
506 zap_page_range(vma, start, end - start);
510 static long madvise_dontneed_free(struct vm_area_struct *vma,
511 struct vm_area_struct **prev,
512 unsigned long start, unsigned long end,
516 if (!can_madv_dontneed_vma(vma))
519 if (!userfaultfd_remove(vma, start, end)) {
520 *prev = NULL; /* mmap_sem has been dropped, prev is stale */
522 down_read(¤t->mm->mmap_sem);
523 vma = find_vma(current->mm, start);
526 if (start < vma->vm_start) {
528 * This "vma" under revalidation is the one
529 * with the lowest vma->vm_start where start
530 * is also < vma->vm_end. If start <
531 * vma->vm_start it means an hole materialized
532 * in the user address space within the
533 * virtual range passed to MADV_DONTNEED
538 if (!can_madv_dontneed_vma(vma))
540 if (end > vma->vm_end) {
542 * Don't fail if end > vma->vm_end. If the old
543 * vma was splitted while the mmap_sem was
544 * released the effect of the concurrent
545 * operation may not cause madvise() to
546 * have an undefined result. There may be an
547 * adjacent next vma that we'll walk
548 * next. userfaultfd_remove() will generate an
549 * UFFD_EVENT_REMOVE repetition on the
550 * end-vma->vm_end range, but the manager can
551 * handle a repetition fine.
555 VM_WARN_ON(start >= end);
558 if (behavior == MADV_DONTNEED)
559 return madvise_dontneed_single_vma(vma, start, end);
560 else if (behavior == MADV_FREE)
561 return madvise_free_single_vma(vma, start, end);
567 * Application wants to free up the pages and associated backing store.
568 * This is effectively punching a hole into the middle of a file.
570 static long madvise_remove(struct vm_area_struct *vma,
571 struct vm_area_struct **prev,
572 unsigned long start, unsigned long end)
578 *prev = NULL; /* tell sys_madvise we drop mmap_sem */
580 if (vma->vm_flags & VM_LOCKED)
585 if (!f || !f->f_mapping || !f->f_mapping->host) {
589 if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE))
592 offset = (loff_t)(start - vma->vm_start)
593 + ((loff_t)vma->vm_pgoff << PAGE_SHIFT);
596 * Filesystem's fallocate may need to take i_mutex. We need to
597 * explicitly grab a reference because the vma (and hence the
598 * vma's reference to the file) can go away as soon as we drop
602 if (userfaultfd_remove(vma, start, end)) {
603 /* mmap_sem was not released by userfaultfd_remove() */
604 up_read(¤t->mm->mmap_sem);
606 error = vfs_fallocate(f,
607 FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE,
608 offset, end - start);
610 down_read(¤t->mm->mmap_sem);
614 #ifdef CONFIG_MEMORY_FAILURE
616 * Error injection support for memory error handling.
618 static int madvise_inject_error(int behavior,
619 unsigned long start, unsigned long end)
625 if (!capable(CAP_SYS_ADMIN))
629 for (; start < end; start += PAGE_SIZE << order) {
633 ret = get_user_pages_fast(start, 1, 0, &page);
636 pfn = page_to_pfn(page);
639 * When soft offlining hugepages, after migrating the page
640 * we dissolve it, therefore in the second loop "page" will
641 * no longer be a compound page, and order will be 0.
643 order = compound_order(compound_head(page));
645 if (PageHWPoison(page)) {
650 if (behavior == MADV_SOFT_OFFLINE) {
651 pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
654 ret = soft_offline_page(page, MF_COUNT_INCREASED);
660 pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n",
664 * Drop the page reference taken by get_user_pages_fast(). In
665 * the absence of MF_COUNT_INCREASED the memory_failure()
666 * routine is responsible for pinning the page to prevent it
667 * from being released back to the page allocator.
670 ret = memory_failure(pfn, 0);
675 /* Ensure that all poisoned pages are removed from per-cpu lists */
676 for_each_populated_zone(zone)
677 drain_all_pages(zone);
684 madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
685 unsigned long start, unsigned long end, int behavior)
689 return madvise_remove(vma, prev, start, end);
691 return madvise_willneed(vma, prev, start, end);
694 return madvise_dontneed_free(vma, prev, start, end, behavior);
696 return madvise_behavior(vma, prev, start, end, behavior);
701 madvise_behavior_valid(int behavior)
707 case MADV_SEQUENTIAL:
715 case MADV_UNMERGEABLE:
717 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
719 case MADV_NOHUGEPAGE:
723 case MADV_WIPEONFORK:
724 case MADV_KEEPONFORK:
725 #ifdef CONFIG_MEMORY_FAILURE
726 case MADV_SOFT_OFFLINE:
737 * The madvise(2) system call.
739 * Applications can use madvise() to advise the kernel how it should
740 * handle paging I/O in this VM area. The idea is to help the kernel
741 * use appropriate read-ahead and caching techniques. The information
742 * provided is advisory only, and can be safely disregarded by the
743 * kernel without affecting the correct operation of the application.
746 * MADV_NORMAL - the default behavior is to read clusters. This
747 * results in some read-ahead and read-behind.
748 * MADV_RANDOM - the system should read the minimum amount of data
749 * on any access, since it is unlikely that the appli-
750 * cation will need more than what it asks for.
751 * MADV_SEQUENTIAL - pages in the given range will probably be accessed
752 * once, so they can be aggressively read ahead, and
753 * can be freed soon after they are accessed.
754 * MADV_WILLNEED - the application is notifying the system to read
756 * MADV_DONTNEED - the application is finished with the given range,
757 * so the kernel can free resources associated with it.
758 * MADV_FREE - the application marks pages in the given range as lazy free,
759 * where actual purges are postponed until memory pressure happens.
760 * MADV_REMOVE - the application wants to free up the given range of
761 * pages and associated backing store.
762 * MADV_DONTFORK - omit this area from child's address space when forking:
763 * typically, to avoid COWing pages pinned by get_user_pages().
764 * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking.
765 * MADV_WIPEONFORK - present the child process with zero-filled memory in this
766 * range after a fork.
767 * MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK
768 * MADV_HWPOISON - trigger memory error handler as if the given memory range
769 * were corrupted by unrecoverable hardware memory failure.
770 * MADV_SOFT_OFFLINE - try to soft-offline the given range of memory.
771 * MADV_MERGEABLE - the application recommends that KSM try to merge pages in
772 * this area with pages of identical content from other such areas.
773 * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others.
774 * MADV_HUGEPAGE - the application wants to back the given range by transparent
775 * huge pages in the future. Existing pages might be coalesced and
776 * new pages might be allocated as THP.
777 * MADV_NOHUGEPAGE - mark the given range as not worth being backed by
778 * transparent huge pages so the existing pages will not be
779 * coalesced into THP and new pages will not be allocated as THP.
780 * MADV_DONTDUMP - the application wants to prevent pages in the given range
781 * from being included in its core dump.
782 * MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
786 * -EINVAL - start + len < 0, start is not page-aligned,
787 * "behavior" is not a valid value, or application
788 * is attempting to release locked or shared pages,
789 * or the specified address range includes file, Huge TLB,
790 * MAP_SHARED or VMPFNMAP range.
791 * -ENOMEM - addresses in the specified range are not currently
792 * mapped, or are outside the AS of the process.
793 * -EIO - an I/O error occurred while paging in data.
794 * -EBADF - map exists, but area maps something that isn't a file.
795 * -EAGAIN - a kernel resource was temporarily unavailable.
797 SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
799 unsigned long end, tmp;
800 struct vm_area_struct *vma, *prev;
801 int unmapped_error = 0;
805 struct blk_plug plug;
807 if (!madvise_behavior_valid(behavior))
810 if (start & ~PAGE_MASK)
812 len = (len_in + ~PAGE_MASK) & PAGE_MASK;
814 /* Check to see whether len was rounded up from small -ve to zero */
826 #ifdef CONFIG_MEMORY_FAILURE
827 if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
828 return madvise_inject_error(behavior, start, start + len_in);
831 write = madvise_need_mmap_write(behavior);
833 if (down_write_killable(¤t->mm->mmap_sem))
836 down_read(¤t->mm->mmap_sem);
840 * If the interval [start,end) covers some unmapped address
841 * ranges, just ignore them, but return -ENOMEM at the end.
842 * - different from the way of handling in mlock etc.
844 vma = find_vma_prev(current->mm, start, &prev);
845 if (vma && start > vma->vm_start)
848 blk_start_plug(&plug);
850 /* Still start < end. */
855 /* Here start < (end|vma->vm_end). */
856 if (start < vma->vm_start) {
857 unmapped_error = -ENOMEM;
858 start = vma->vm_start;
863 /* Here vma->vm_start <= start < (end|vma->vm_end) */
868 /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
869 error = madvise_vma(vma, &prev, start, tmp, behavior);
873 if (prev && start < prev->vm_end)
874 start = prev->vm_end;
875 error = unmapped_error;
880 else /* madvise_remove dropped mmap_sem */
881 vma = find_vma(current->mm, start);
884 blk_finish_plug(&plug);
886 up_write(¤t->mm->mmap_sem);
888 up_read(¤t->mm->mmap_sem);