| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * linux/mm/madvise.c |
| * |
| * Copyright (C) 1999 Linus Torvalds |
| * Copyright (C) 2002 Christoph Hellwig |
| */ |
| |
| #include <linux/mman.h> |
| #include <linux/pagemap.h> |
| #include <linux/syscalls.h> |
| #include <linux/mempolicy.h> |
| #include <linux/page-isolation.h> |
| #include <linux/page_idle.h> |
| #include <linux/userfaultfd_k.h> |
| #include <linux/hugetlb.h> |
| #include <linux/falloc.h> |
| #include <linux/fadvise.h> |
| #include <linux/sched.h> |
| #include <linux/sched/mm.h> |
| #include <linux/uio.h> |
| #include <linux/ksm.h> |
| #include <linux/fs.h> |
| #include <linux/file.h> |
| #include <linux/blkdev.h> |
| #include <linux/backing-dev.h> |
| #include <linux/pagewalk.h> |
| #include <linux/swap.h> |
| #include <linux/swapops.h> |
| #include <linux/shmem_fs.h> |
| #include <linux/mmu_notifier.h> |
| |
| #include <asm/tlb.h> |
| |
| #include "internal.h" |
| |
| struct madvise_walk_private { |
| struct mmu_gather *tlb; |
| bool pageout; |
| }; |
| |
| /* |
| * Any behaviour which results in changes to the vma->vm_flags needs to |
| * take mmap_lock for writing. Others, which simply traverse vmas, need |
| * to only take it for reading. |
| */ |
| static int madvise_need_mmap_write(int behavior) |
| { |
| switch (behavior) { |
| case MADV_REMOVE: |
| case MADV_WILLNEED: |
| case MADV_DONTNEED: |
| case MADV_COLD: |
| case MADV_PAGEOUT: |
| case MADV_FREE: |
| case MADV_POPULATE_READ: |
| case MADV_POPULATE_WRITE: |
| return 0; |
| default: |
| /* be safe, default to 1. list exceptions explicitly */ |
| return 1; |
| } |
| } |
| |
| /* |
| * We can potentially split a vm area into separate |
| * areas, each area with its own behavior. |
| */ |
| static long madvise_behavior(struct vm_area_struct *vma, |
| struct vm_area_struct **prev, |
| unsigned long start, unsigned long end, int behavior) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| int error = 0; |
| pgoff_t pgoff; |
| unsigned long new_flags = vma->vm_flags; |
| |
| switch (behavior) { |
| case MADV_NORMAL: |
| new_flags = new_flags & ~VM_RAND_READ & ~VM_SEQ_READ; |
| break; |
| case MADV_SEQUENTIAL: |
| new_flags = (new_flags & ~VM_RAND_READ) | VM_SEQ_READ; |
| break; |
| case MADV_RANDOM: |
| new_flags = (new_flags & ~VM_SEQ_READ) | VM_RAND_READ; |
| break; |
| case MADV_DONTFORK: |
| new_flags |= VM_DONTCOPY; |
| break; |
| case MADV_DOFORK: |
| if (vma->vm_flags & VM_IO) { |
| error = -EINVAL; |
| goto out; |
| } |
| new_flags &= ~VM_DONTCOPY; |
| break; |
| case MADV_WIPEONFORK: |
| /* MADV_WIPEONFORK is only supported on anonymous memory. */ |
| if (vma->vm_file || vma->vm_flags & VM_SHARED) { |
| error = -EINVAL; |
| goto out; |
| } |
| new_flags |= VM_WIPEONFORK; |
| break; |
| case MADV_KEEPONFORK: |
| new_flags &= ~VM_WIPEONFORK; |
| break; |
| case MADV_DONTDUMP: |
| new_flags |= VM_DONTDUMP; |
| break; |
| case MADV_DODUMP: |
| if (!is_vm_hugetlb_page(vma) && new_flags & VM_SPECIAL) { |
| error = -EINVAL; |
| goto out; |
| } |
| new_flags &= ~VM_DONTDUMP; |
| break; |
| case MADV_MERGEABLE: |
| case MADV_UNMERGEABLE: |
| error = ksm_madvise(vma, start, end, behavior, &new_flags); |
| if (error) |
| goto out_convert_errno; |
| break; |
| case MADV_HUGEPAGE: |
| case MADV_NOHUGEPAGE: |
| error = hugepage_madvise(vma, &new_flags, behavior); |
| if (error) |
| goto out_convert_errno; |
| break; |
| } |
| |
| if (new_flags == vma->vm_flags) { |
| *prev = vma; |
| goto out; |
| } |
| |
| pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); |
| *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma, |
| vma->vm_file, pgoff, vma_policy(vma), |
| vma->vm_userfaultfd_ctx); |
| if (*prev) { |
| vma = *prev; |
| goto success; |
| } |
| |
| *prev = vma; |
| |
| if (start != vma->vm_start) { |
| if (unlikely(mm->map_count >= sysctl_max_map_count)) { |
| error = -ENOMEM; |
| goto out; |
| } |
| error = __split_vma(mm, vma, start, 1); |
| if (error) |
| goto out_convert_errno; |
| } |
| |
| if (end != vma->vm_end) { |
| if (unlikely(mm->map_count >= sysctl_max_map_count)) { |
| error = -ENOMEM; |
| goto out; |
| } |
| error = __split_vma(mm, vma, end, 0); |
| if (error) |
| goto out_convert_errno; |
| } |
| |
| success: |
| /* |
| * vm_flags is protected by the mmap_lock held in write mode. |
| */ |
| vma->vm_flags = new_flags; |
| |
| out_convert_errno: |
| /* |
| * madvise() returns EAGAIN if kernel resources, such as |
| * slab, are temporarily unavailable. |
| */ |
| if (error == -ENOMEM) |
| error = -EAGAIN; |
| out: |
| return error; |
| } |
| |
| #ifdef CONFIG_SWAP |
| static int swapin_walk_pmd_entry(pmd_t *pmd, unsigned long start, |
| unsigned long end, struct mm_walk *walk) |
| { |
| pte_t *orig_pte; |
| struct vm_area_struct *vma = walk->private; |
| unsigned long index; |
| |
| if (pmd_none_or_trans_huge_or_clear_bad(pmd)) |
| return 0; |
| |
| for (index = start; index != end; index += PAGE_SIZE) { |
| pte_t pte; |
| swp_entry_t entry; |
| struct page *page; |
| spinlock_t *ptl; |
| |
| orig_pte = pte_offset_map_lock(vma->vm_mm, pmd, start, &ptl); |
| pte = *(orig_pte + ((index - start) / PAGE_SIZE)); |
| pte_unmap_unlock(orig_pte, ptl); |
| |
| if (pte_present(pte) || pte_none(pte)) |
| continue; |
| entry = pte_to_swp_entry(pte); |
| if (unlikely(non_swap_entry(entry))) |
| continue; |
| |
| page = read_swap_cache_async(entry, GFP_HIGHUSER_MOVABLE, |
| vma, index, false); |
| if (page) |
| put_page(page); |
| } |
| |
| return 0; |
| } |
| |
| static const struct mm_walk_ops swapin_walk_ops = { |
| .pmd_entry = swapin_walk_pmd_entry, |
| }; |
| |
| static void force_shm_swapin_readahead(struct vm_area_struct *vma, |
| unsigned long start, unsigned long end, |
| struct address_space *mapping) |
| { |
| XA_STATE(xas, &mapping->i_pages, linear_page_index(vma, start)); |
| pgoff_t end_index = linear_page_index(vma, end + PAGE_SIZE - 1); |
| struct page *page; |
| |
| rcu_read_lock(); |
| xas_for_each(&xas, page, end_index) { |
| swp_entry_t swap; |
| |
| if (!xa_is_value(page)) |
| continue; |
| xas_pause(&xas); |
| rcu_read_unlock(); |
| |
| swap = radix_to_swp_entry(page); |
| page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE, |
| NULL, 0, false); |
| if (page) |
| put_page(page); |
| |
| rcu_read_lock(); |
| } |
| rcu_read_unlock(); |
| |
| lru_add_drain(); /* Push any new pages onto the LRU now */ |
| } |
| #endif /* CONFIG_SWAP */ |
| |
| /* |
| * Schedule all required I/O operations. Do not wait for completion. |
| */ |
| static long madvise_willneed(struct vm_area_struct *vma, |
| struct vm_area_struct **prev, |
| unsigned long start, unsigned long end) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| struct file *file = vma->vm_file; |
| loff_t offset; |
| |
| *prev = vma; |
| #ifdef CONFIG_SWAP |
| if (!file) { |
| walk_page_range(vma->vm_mm, start, end, &swapin_walk_ops, vma); |
| lru_add_drain(); /* Push any new pages onto the LRU now */ |
| return 0; |
| } |
| |
| if (shmem_mapping(file->f_mapping)) { |
| force_shm_swapin_readahead(vma, start, end, |
| file->f_mapping); |
| return 0; |
| } |
| #else |
| if (!file) |
| return -EBADF; |
| #endif |
| |
| if (IS_DAX(file_inode(file))) { |
| /* no bad return value, but ignore advice */ |
| return 0; |
| } |
| |
| /* |
| * Filesystem's fadvise may need to take various locks. We need to |
| * explicitly grab a reference because the vma (and hence the |
| * vma's reference to the file) can go away as soon as we drop |
| * mmap_lock. |
| */ |
| *prev = NULL; /* tell sys_madvise we drop mmap_lock */ |
| get_file(file); |
| offset = (loff_t)(start - vma->vm_start) |
| + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); |
| mmap_read_unlock(mm); |
| vfs_fadvise(file, offset, end - start, POSIX_FADV_WILLNEED); |
| fput(file); |
| mmap_read_lock(mm); |
| return 0; |
| } |
| |
| static int madvise_cold_or_pageout_pte_range(pmd_t *pmd, |
| unsigned long addr, unsigned long end, |
| struct mm_walk *walk) |
| { |
| struct madvise_walk_private *private = walk->private; |
| struct mmu_gather *tlb = private->tlb; |
| bool pageout = private->pageout; |
| struct mm_struct *mm = tlb->mm; |
| struct vm_area_struct *vma = walk->vma; |
| pte_t *orig_pte, *pte, ptent; |
| spinlock_t *ptl; |
| struct page *page = NULL; |
| LIST_HEAD(page_list); |
| |
| if (fatal_signal_pending(current)) |
| return -EINTR; |
| |
| #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
| if (pmd_trans_huge(*pmd)) { |
| pmd_t orig_pmd; |
| unsigned long next = pmd_addr_end(addr, end); |
| |
| tlb_change_page_size(tlb, HPAGE_PMD_SIZE); |
| ptl = pmd_trans_huge_lock(pmd, vma); |
| if (!ptl) |
| return 0; |
| |
| orig_pmd = *pmd; |
| if (is_huge_zero_pmd(orig_pmd)) |
| goto huge_unlock; |
| |
| if (unlikely(!pmd_present(orig_pmd))) { |
| VM_BUG_ON(thp_migration_supported() && |
| !is_pmd_migration_entry(orig_pmd)); |
| goto huge_unlock; |
| } |
| |
| page = pmd_page(orig_pmd); |
| |
| /* Do not interfere with other mappings of this page */ |
| if (page_mapcount(page) != 1) |
| goto huge_unlock; |
| |
| if (next - addr != HPAGE_PMD_SIZE) { |
| int err; |
| |
| get_page(page); |
| spin_unlock(ptl); |
| lock_page(page); |
| err = split_huge_page(page); |
| unlock_page(page); |
| put_page(page); |
| if (!err) |
| goto regular_page; |
| return 0; |
| } |
| |
| if (pmd_young(orig_pmd)) { |
| pmdp_invalidate(vma, addr, pmd); |
| orig_pmd = pmd_mkold(orig_pmd); |
| |
| set_pmd_at(mm, addr, pmd, orig_pmd); |
| tlb_remove_pmd_tlb_entry(tlb, pmd, addr); |
| } |
| |
| ClearPageReferenced(page); |
| test_and_clear_page_young(page); |
| if (pageout) { |
| if (!isolate_lru_page(page)) { |
| if (PageUnevictable(page)) |
| putback_lru_page(page); |
| else |
| list_add(&page->lru, &page_list); |
| } |
| } else |
| deactivate_page(page); |
| huge_unlock: |
| spin_unlock(ptl); |
| if (pageout) |
| reclaim_pages(&page_list); |
| return 0; |
| } |
| |
| regular_page: |
| if (pmd_trans_unstable(pmd)) |
| return 0; |
| #endif |
| tlb_change_page_size(tlb, PAGE_SIZE); |
| orig_pte = pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); |
| flush_tlb_batched_pending(mm); |
| arch_enter_lazy_mmu_mode(); |
| for (; addr < end; pte++, addr += PAGE_SIZE) { |
| ptent = *pte; |
| |
| if (pte_none(ptent)) |
| continue; |
| |
| if (!pte_present(ptent)) |
| continue; |
| |
| page = vm_normal_page(vma, addr, ptent); |
| if (!page) |
| continue; |
| |
| /* |
| * Creating a THP page is expensive so split it only if we |
| * are sure it's worth. Split it if we are only owner. |
| */ |
| if (PageTransCompound(page)) { |
| if (page_mapcount(page) != 1) |
| break; |
| get_page(page); |
| if (!trylock_page(page)) { |
| put_page(page); |
| break; |
| } |
| pte_unmap_unlock(orig_pte, ptl); |
| if (split_huge_page(page)) { |
| unlock_page(page); |
| put_page(page); |
| pte_offset_map_lock(mm, pmd, addr, &ptl); |
| break; |
| } |
| unlock_page(page); |
| put_page(page); |
| pte = pte_offset_map_lock(mm, pmd, addr, &ptl); |
| pte--; |
| addr -= PAGE_SIZE; |
| continue; |
| } |
| |
| /* Do not interfere with other mappings of this page */ |
| if (page_mapcount(page) != 1) |
| continue; |
| |
| VM_BUG_ON_PAGE(PageTransCompound(page), page); |
| |
| if (pte_young(ptent)) { |
| ptent = ptep_get_and_clear_full(mm, addr, pte, |
| tlb->fullmm); |
| ptent = pte_mkold(ptent); |
| set_pte_at(mm, addr, pte, ptent); |
| tlb_remove_tlb_entry(tlb, pte, addr); |
| } |
| |
| /* |
| * We are deactivating a page for accelerating reclaiming. |
| * VM couldn't reclaim the page unless we clear PG_young. |
| * As a side effect, it makes confuse idle-page tracking |
| * because they will miss recent referenced history. |
| */ |
| ClearPageReferenced(page); |
| test_and_clear_page_young(page); |
| if (pageout) { |
| if (!isolate_lru_page(page)) { |
| if (PageUnevictable(page)) |
| putback_lru_page(page); |
| else |
| list_add(&page->lru, &page_list); |
| } |
| } else |
| deactivate_page(page); |
| } |
| |
| arch_leave_lazy_mmu_mode(); |
| pte_unmap_unlock(orig_pte, ptl); |
| if (pageout) |
| reclaim_pages(&page_list); |
| cond_resched(); |
| |
| return 0; |
| } |
| |
| static const struct mm_walk_ops cold_walk_ops = { |
| .pmd_entry = madvise_cold_or_pageout_pte_range, |
| }; |
| |
| static void madvise_cold_page_range(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, |
| unsigned long addr, unsigned long end) |
| { |
| struct madvise_walk_private walk_private = { |
| .pageout = false, |
| .tlb = tlb, |
| }; |
| |
| tlb_start_vma(tlb, vma); |
| walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private); |
| tlb_end_vma(tlb, vma); |
| } |
| |
| static long madvise_cold(struct vm_area_struct *vma, |
| struct vm_area_struct **prev, |
| unsigned long start_addr, unsigned long end_addr) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| struct mmu_gather tlb; |
| |
| *prev = vma; |
| if (!can_madv_lru_vma(vma)) |
| return -EINVAL; |
| |
| lru_add_drain(); |
| tlb_gather_mmu(&tlb, mm); |
| madvise_cold_page_range(&tlb, vma, start_addr, end_addr); |
| tlb_finish_mmu(&tlb); |
| |
| return 0; |
| } |
| |
| static void madvise_pageout_page_range(struct mmu_gather *tlb, |
| struct vm_area_struct *vma, |
| unsigned long addr, unsigned long end) |
| { |
| struct madvise_walk_private walk_private = { |
| .pageout = true, |
| .tlb = tlb, |
| }; |
| |
| tlb_start_vma(tlb, vma); |
| walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private); |
| tlb_end_vma(tlb, vma); |
| } |
| |
| static inline bool can_do_pageout(struct vm_area_struct *vma) |
| { |
| if (vma_is_anonymous(vma)) |
| return true; |
| if (!vma->vm_file) |
| return false; |
| /* |
| * paging out pagecache only for non-anonymous mappings that correspond |
| * to the files the calling process could (if tried) open for writing; |
| * otherwise we'd be including shared non-exclusive mappings, which |
| * opens a side channel. |
| */ |
| return inode_owner_or_capable(&init_user_ns, |
| file_inode(vma->vm_file)) || |
| file_permission(vma->vm_file, MAY_WRITE) == 0; |
| } |
| |
| static long madvise_pageout(struct vm_area_struct *vma, |
| struct vm_area_struct **prev, |
| unsigned long start_addr, unsigned long end_addr) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| struct mmu_gather tlb; |
| |
| *prev = vma; |
| if (!can_madv_lru_vma(vma)) |
| return -EINVAL; |
| |
| if (!can_do_pageout(vma)) |
| return 0; |
| |
| lru_add_drain(); |
| tlb_gather_mmu(&tlb, mm); |
| madvise_pageout_page_range(&tlb, vma, start_addr, end_addr); |
| tlb_finish_mmu(&tlb); |
| |
| return 0; |
| } |
| |
| static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr, |
| unsigned long end, struct mm_walk *walk) |
| |
| { |
| struct mmu_gather *tlb = walk->private; |
| struct mm_struct *mm = tlb->mm; |
| struct vm_area_struct *vma = walk->vma; |
| spinlock_t *ptl; |
| pte_t *orig_pte, *pte, ptent; |
| struct page *page; |
| int nr_swap = 0; |
| unsigned long next; |
| |
| next = pmd_addr_end(addr, end); |
| if (pmd_trans_huge(*pmd)) |
| if (madvise_free_huge_pmd(tlb, vma, pmd, addr, next)) |
| goto next; |
| |
| if (pmd_trans_unstable(pmd)) |
| return 0; |
| |
| tlb_change_page_size(tlb, PAGE_SIZE); |
| orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl); |
| flush_tlb_batched_pending(mm); |
| arch_enter_lazy_mmu_mode(); |
| for (; addr != end; pte++, addr += PAGE_SIZE) { |
| ptent = *pte; |
| |
| if (pte_none(ptent)) |
| continue; |
| /* |
| * If the pte has swp_entry, just clear page table to |
| * prevent swap-in which is more expensive rather than |
| * (page allocation + zeroing). |
| */ |
| if (!pte_present(ptent)) { |
| swp_entry_t entry; |
| |
| entry = pte_to_swp_entry(ptent); |
| if (non_swap_entry(entry)) |
| continue; |
| nr_swap--; |
| free_swap_and_cache(entry); |
| pte_clear_not_present_full(mm, addr, pte, tlb->fullmm); |
| continue; |
| } |
| |
| page = vm_normal_page(vma, addr, ptent); |
| if (!page) |
| continue; |
| |
| /* |
| * If pmd isn't transhuge but the page is THP and |
| * is owned by only this process, split it and |
| * deactivate all pages. |
| */ |
| if (PageTransCompound(page)) { |
| if (page_mapcount(page) != 1) |
| goto out; |
| get_page(page); |
| if (!trylock_page(page)) { |
| put_page(page); |
| goto out; |
| } |
| pte_unmap_unlock(orig_pte, ptl); |
| if (split_huge_page(page)) { |
| unlock_page(page); |
| put_page(page); |
| pte_offset_map_lock(mm, pmd, addr, &ptl); |
| goto out; |
| } |
| unlock_page(page); |
| put_page(page); |
| pte = pte_offset_map_lock(mm, pmd, addr, &ptl); |
| pte--; |
| addr -= PAGE_SIZE; |
| continue; |
| } |
| |
| VM_BUG_ON_PAGE(PageTransCompound(page), page); |
| |
| if (PageSwapCache(page) || PageDirty(page)) { |
| if (!trylock_page(page)) |
| continue; |
| /* |
| * If page is shared with others, we couldn't clear |
| * PG_dirty of the page. |
| */ |
| if (page_mapcount(page) != 1) { |
| unlock_page(page); |
| continue; |
| } |
| |
| if (PageSwapCache(page) && !try_to_free_swap(page)) { |
| unlock_page(page); |
| continue; |
| } |
| |
| ClearPageDirty(page); |
| unlock_page(page); |
| } |
| |
| if (pte_young(ptent) || pte_dirty(ptent)) { |
| /* |
| * Some of architecture(ex, PPC) don't update TLB |
| * with set_pte_at and tlb_remove_tlb_entry so for |
| * the portability, remap the pte with old|clean |
| * after pte clearing. |
| */ |
| ptent = ptep_get_and_clear_full(mm, addr, pte, |
| tlb->fullmm); |
| |
| ptent = pte_mkold(ptent); |
| ptent = pte_mkclean(ptent); |
| set_pte_at(mm, addr, pte, ptent); |
| tlb_remove_tlb_entry(tlb, pte, addr); |
| } |
| mark_page_lazyfree(page); |
| } |
| out: |
| if (nr_swap) { |
| if (current->mm == mm) |
| sync_mm_rss(mm); |
| |
| add_mm_counter(mm, MM_SWAPENTS, nr_swap); |
| } |
| arch_leave_lazy_mmu_mode(); |
| pte_unmap_unlock(orig_pte, ptl); |
| cond_resched(); |
| next: |
| return 0; |
| } |
| |
| static const struct mm_walk_ops madvise_free_walk_ops = { |
| .pmd_entry = madvise_free_pte_range, |
| }; |
| |
| static int madvise_free_single_vma(struct vm_area_struct *vma, |
| unsigned long start_addr, unsigned long end_addr) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| struct mmu_notifier_range range; |
| struct mmu_gather tlb; |
| |
| /* MADV_FREE works for only anon vma at the moment */ |
| if (!vma_is_anonymous(vma)) |
| return -EINVAL; |
| |
| range.start = max(vma->vm_start, start_addr); |
| if (range.start >= vma->vm_end) |
| return -EINVAL; |
| range.end = min(vma->vm_end, end_addr); |
| if (range.end <= vma->vm_start) |
| return -EINVAL; |
| mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, mm, |
| range.start, range.end); |
| |
| lru_add_drain(); |
| tlb_gather_mmu(&tlb, mm); |
| update_hiwater_rss(mm); |
| |
| mmu_notifier_invalidate_range_start(&range); |
| tlb_start_vma(&tlb, vma); |
| walk_page_range(vma->vm_mm, range.start, range.end, |
| &madvise_free_walk_ops, &tlb); |
| tlb_end_vma(&tlb, vma); |
| mmu_notifier_invalidate_range_end(&range); |
| tlb_finish_mmu(&tlb); |
| |
| return 0; |
| } |
| |
| /* |
| * Application no longer needs these pages. If the pages are dirty, |
| * it's OK to just throw them away. The app will be more careful about |
| * data it wants to keep. Be sure to free swap resources too. The |
| * zap_page_range call sets things up for shrink_active_list to actually free |
| * these pages later if no one else has touched them in the meantime, |
| * although we could add these pages to a global reuse list for |
| * shrink_active_list to pick up before reclaiming other pages. |
| * |
| * NB: This interface discards data rather than pushes it out to swap, |
| * as some implementations do. This has performance implications for |
| * applications like large transactional databases which want to discard |
| * pages in anonymous maps after committing to backing store the data |
| * that was kept in them. There is no reason to write this data out to |
| * the swap area if the application is discarding it. |
| * |
| * An interface that causes the system to free clean pages and flush |
| * dirty pages is already available as msync(MS_INVALIDATE). |
| */ |
| static long madvise_dontneed_single_vma(struct vm_area_struct *vma, |
| unsigned long start, unsigned long end) |
| { |
| zap_page_range(vma, start, end - start); |
| return 0; |
| } |
| |
| static long madvise_dontneed_free(struct vm_area_struct *vma, |
| struct vm_area_struct **prev, |
| unsigned long start, unsigned long end, |
| int behavior) |
| { |
| struct mm_struct *mm = vma->vm_mm; |
| |
| *prev = vma; |
| if (!can_madv_lru_vma(vma)) |
| return -EINVAL; |
| |
| if (!userfaultfd_remove(vma, start, end)) { |
| *prev = NULL; /* mmap_lock has been dropped, prev is stale */ |
| |
| mmap_read_lock(mm); |
| vma = find_vma(mm, start); |
| if (!vma) |
| return -ENOMEM; |
| if (start < vma->vm_start) { |
| /* |
| * This "vma" under revalidation is the one |
| * with the lowest vma->vm_start where start |
| * is also < vma->vm_end. If start < |
| * vma->vm_start it means an hole materialized |
| * in the user address space within the |
| * virtual range passed to MADV_DONTNEED |
| * or MADV_FREE. |
| */ |
| return -ENOMEM; |
| } |
| if (!can_madv_lru_vma(vma)) |
| return -EINVAL; |
| if (end > vma->vm_end) { |
| /* |
| * Don't fail if end > vma->vm_end. If the old |
| * vma was split while the mmap_lock was |
| * released the effect of the concurrent |
| * operation may not cause madvise() to |
| * have an undefined result. There may be an |
| * adjacent next vma that we'll walk |
| * next. userfaultfd_remove() will generate an |
| * UFFD_EVENT_REMOVE repetition on the |
| * end-vma->vm_end range, but the manager can |
| * handle a repetition fine. |
| */ |
| end = vma->vm_end; |
| } |
| VM_WARN_ON(start >= end); |
| } |
| |
| if (behavior == MADV_DONTNEED) |
| return madvise_dontneed_single_vma(vma, start, end); |
| else if (behavior == MADV_FREE) |
| return madvise_free_single_vma(vma, start, end); |
| else |
| return -EINVAL; |
| } |
| |
| static long madvise_populate(struct vm_area_struct *vma, |
| struct vm_area_struct **prev, |
| unsigned long start, unsigned long end, |
| int behavior) |
| { |
| const bool write = behavior == MADV_POPULATE_WRITE; |
| struct mm_struct *mm = vma->vm_mm; |
| unsigned long tmp_end; |
| int locked = 1; |
| long pages; |
| |
| *prev = vma; |
| |
| while (start < end) { |
| /* |
| * We might have temporarily dropped the lock. For example, |
| * our VMA might have been split. |
| */ |
| if (!vma || start >= vma->vm_end) { |
| vma = find_vma(mm, start); |
| if (!vma || start < vma->vm_start) |
| return -ENOMEM; |
| } |
| |
| tmp_end = min_t(unsigned long, end, vma->vm_end); |
| /* Populate (prefault) page tables readable/writable. */ |
| pages = faultin_vma_page_range(vma, start, tmp_end, write, |
| &locked); |
| if (!locked) { |
| mmap_read_lock(mm); |
| locked = 1; |
| *prev = NULL; |
| vma = NULL; |
| } |
| if (pages < 0) { |
| switch (pages) { |
| case -EINTR: |
| return -EINTR; |
| case -EINVAL: /* Incompatible mappings / permissions. */ |
| return -EINVAL; |
| case -EHWPOISON: |
| return -EHWPOISON; |
| case -EFAULT: /* VM_FAULT_SIGBUS or VM_FAULT_SIGSEGV */ |
| return -EFAULT; |
| default: |
| pr_warn_once("%s: unhandled return value: %ld\n", |
| __func__, pages); |
| fallthrough; |
| case -ENOMEM: |
| return -ENOMEM; |
| } |
| } |
| start += pages * PAGE_SIZE; |
| } |
| return 0; |
| } |
| |
| /* |
| * Application wants to free up the pages and associated backing store. |
| * This is effectively punching a hole into the middle of a file. |
| */ |
| static long madvise_remove(struct vm_area_struct *vma, |
| struct vm_area_struct **prev, |
| unsigned long start, unsigned long end) |
| { |
| loff_t offset; |
| int error; |
| struct file *f; |
| struct mm_struct *mm = vma->vm_mm; |
| |
| *prev = NULL; /* tell sys_madvise we drop mmap_lock */ |
| |
| if (vma->vm_flags & VM_LOCKED) |
| return -EINVAL; |
| |
| f = vma->vm_file; |
| |
| if (!f || !f->f_mapping || !f->f_mapping->host) { |
| return -EINVAL; |
| } |
| |
| if ((vma->vm_flags & (VM_SHARED|VM_WRITE)) != (VM_SHARED|VM_WRITE)) |
| return -EACCES; |
| |
| offset = (loff_t)(start - vma->vm_start) |
| + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); |
| |
| /* |
| * Filesystem's fallocate may need to take i_mutex. We need to |
| * explicitly grab a reference because the vma (and hence the |
| * vma's reference to the file) can go away as soon as we drop |
| * mmap_lock. |
| */ |
| get_file(f); |
| if (userfaultfd_remove(vma, start, end)) { |
| /* mmap_lock was not released by userfaultfd_remove() */ |
| mmap_read_unlock(mm); |
| } |
| error = vfs_fallocate(f, |
| FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, |
| offset, end - start); |
| fput(f); |
| mmap_read_lock(mm); |
| return error; |
| } |
| |
| #ifdef CONFIG_MEMORY_FAILURE |
| /* |
| * Error injection support for memory error handling. |
| */ |
| static int madvise_inject_error(int behavior, |
| unsigned long start, unsigned long end) |
| { |
| unsigned long size; |
| |
| if (!capable(CAP_SYS_ADMIN)) |
| return -EPERM; |
| |
| |
| for (; start < end; start += size) { |
| unsigned long pfn; |
| struct page *page; |
| int ret; |
| |
| ret = get_user_pages_fast(start, 1, 0, &page); |
| if (ret != 1) |
| return ret; |
| pfn = page_to_pfn(page); |
| |
| /* |
| * When soft offlining hugepages, after migrating the page |
| * we dissolve it, therefore in the second loop "page" will |
| * no longer be a compound page. |
| */ |
| size = page_size(compound_head(page)); |
| |
| if (behavior == MADV_SOFT_OFFLINE) { |
| pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n", |
| pfn, start); |
| ret = soft_offline_page(pfn, MF_COUNT_INCREASED); |
| } else { |
| pr_info("Injecting memory failure for pfn %#lx at process virtual address %#lx\n", |
| pfn, start); |
| ret = memory_failure(pfn, MF_COUNT_INCREASED); |
| } |
| |
| if (ret) |
| return ret; |
| } |
| |
| return 0; |
| } |
| #endif |
| |
| static long |
| madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev, |
| unsigned long start, unsigned long end, int behavior) |
| { |
| switch (behavior) { |
| case MADV_REMOVE: |
| return madvise_remove(vma, prev, start, end); |
| case MADV_WILLNEED: |
| return madvise_willneed(vma, prev, start, end); |
| case MADV_COLD: |
| return madvise_cold(vma, prev, start, end); |
| case MADV_PAGEOUT: |
| return madvise_pageout(vma, prev, start, end); |
| case MADV_FREE: |
| case MADV_DONTNEED: |
| return madvise_dontneed_free(vma, prev, start, end, behavior); |
| case MADV_POPULATE_READ: |
| case MADV_POPULATE_WRITE: |
| return madvise_populate(vma, prev, start, end, behavior); |
| default: |
| return madvise_behavior(vma, prev, start, end, behavior); |
| } |
| } |
| |
| static bool |
| madvise_behavior_valid(int behavior) |
| { |
| switch (behavior) { |
| case MADV_DOFORK: |
| case MADV_DONTFORK: |
| case MADV_NORMAL: |
| case MADV_SEQUENTIAL: |
| case MADV_RANDOM: |
| case MADV_REMOVE: |
| case MADV_WILLNEED: |
| case MADV_DONTNEED: |
| case MADV_FREE: |
| case MADV_COLD: |
| case MADV_PAGEOUT: |
| case MADV_POPULATE_READ: |
| case MADV_POPULATE_WRITE: |
| #ifdef CONFIG_KSM |
| case MADV_MERGEABLE: |
| case MADV_UNMERGEABLE: |
| #endif |
| #ifdef CONFIG_TRANSPARENT_HUGEPAGE |
| case MADV_HUGEPAGE: |
| case MADV_NOHUGEPAGE: |
| #endif |
| case MADV_DONTDUMP: |
| case MADV_DODUMP: |
| case MADV_WIPEONFORK: |
| case MADV_KEEPONFORK: |
| #ifdef CONFIG_MEMORY_FAILURE |
| case MADV_SOFT_OFFLINE: |
| case MADV_HWPOISON: |
| #endif |
| return true; |
| |
| default: |
| return false; |
| } |
| } |
| |
| static bool |
| process_madvise_behavior_valid(int behavior) |
| { |
| switch (behavior) { |
| case MADV_COLD: |
| case MADV_PAGEOUT: |
| return true; |
| default: |
| return false; |
| } |
| } |
| |
| /* |
| * The madvise(2) system call. |
| * |
| * Applications can use madvise() to advise the kernel how it should |
| * handle paging I/O in this VM area. The idea is to help the kernel |
| * use appropriate read-ahead and caching techniques. The information |
| * provided is advisory only, and can be safely disregarded by the |
| * kernel without affecting the correct operation of the application. |
| * |
| * behavior values: |
| * MADV_NORMAL - the default behavior is to read clusters. This |
| * results in some read-ahead and read-behind. |
| * MADV_RANDOM - the system should read the minimum amount of data |
| * on any access, since it is unlikely that the appli- |
| * cation will need more than what it asks for. |
| * MADV_SEQUENTIAL - pages in the given range will probably be accessed |
| * once, so they can be aggressively read ahead, and |
| * can be freed soon after they are accessed. |
| * MADV_WILLNEED - the application is notifying the system to read |
| * some pages ahead. |
| * MADV_DONTNEED - the application is finished with the given range, |
| * so the kernel can free resources associated with it. |
| * MADV_FREE - the application marks pages in the given range as lazy free, |
| * where actual purges are postponed until memory pressure happens. |
| * MADV_REMOVE - the application wants to free up the given range of |
| * pages and associated backing store. |
| * MADV_DONTFORK - omit this area from child's address space when forking: |
| * typically, to avoid COWing pages pinned by get_user_pages(). |
| * MADV_DOFORK - cancel MADV_DONTFORK: no longer omit this area when forking. |
| * MADV_WIPEONFORK - present the child process with zero-filled memory in this |
| * range after a fork. |
| * MADV_KEEPONFORK - undo the effect of MADV_WIPEONFORK |
| * MADV_HWPOISON - trigger memory error handler as if the given memory range |
| * were corrupted by unrecoverable hardware memory failure. |
| * MADV_SOFT_OFFLINE - try to soft-offline the given range of memory. |
| * MADV_MERGEABLE - the application recommends that KSM try to merge pages in |
| * this area with pages of identical content from other such areas. |
| * MADV_UNMERGEABLE- cancel MADV_MERGEABLE: no longer merge pages with others. |
| * MADV_HUGEPAGE - the application wants to back the given range by transparent |
| * huge pages in the future. Existing pages might be coalesced and |
| * new pages might be allocated as THP. |
| * MADV_NOHUGEPAGE - mark the given range as not worth being backed by |
| * transparent huge pages so the existing pages will not be |
| * coalesced into THP and new pages will not be allocated as THP. |
| * MADV_DONTDUMP - the application wants to prevent pages in the given range |
| * from being included in its core dump. |
| * MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump. |
| * MADV_COLD - the application is not expected to use this memory soon, |
| * deactivate pages in this range so that they can be reclaimed |
| * easily if memory pressure happens. |
| * MADV_PAGEOUT - the application is not expected to use this memory soon, |
| * page out the pages in this range immediately. |
| * MADV_POPULATE_READ - populate (prefault) page tables readable by |
| * triggering read faults if required |
| * MADV_POPULATE_WRITE - populate (prefault) page tables writable by |
| * triggering write faults if required |
| * |
| * return values: |
| * zero - success |
| * -EINVAL - start + len < 0, start is not page-aligned, |
| * "behavior" is not a valid value, or application |
| * is attempting to release locked or shared pages, |
| * or the specified address range includes file, Huge TLB, |
| * MAP_SHARED or VMPFNMAP range. |
| * -ENOMEM - addresses in the specified range are not currently |
| * mapped, or are outside the AS of the process. |
| * -EIO - an I/O error occurred while paging in data. |
| * -EBADF - map exists, but area maps something that isn't a file. |
| * -EAGAIN - a kernel resource was temporarily unavailable. |
| */ |
| int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior) |
| { |
| unsigned long end, tmp; |
| struct vm_area_struct *vma, *prev; |
| int unmapped_error = 0; |
| int error = -EINVAL; |
| int write; |
| size_t len; |
| struct blk_plug plug; |
| |
| start = untagged_addr(start); |
| |
| if (!madvise_behavior_valid(behavior)) |
| return error; |
| |
| if (!PAGE_ALIGNED(start)) |
| return error; |
| len = PAGE_ALIGN(len_in); |
| |
| /* Check to see whether len was rounded up from small -ve to zero */ |
| if (len_in && !len) |
| return error; |
| |
| end = start + len; |
| if (end < start) |
| return error; |
| |
| error = 0; |
| if (end == start) |
| return error; |
| |
| #ifdef CONFIG_MEMORY_FAILURE |
| if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE) |
| return madvise_inject_error(behavior, start, start + len_in); |
| #endif |
| |
| write = madvise_need_mmap_write(behavior); |
| if (write) { |
| if (mmap_write_lock_killable(mm)) |
| return -EINTR; |
| } else { |
| mmap_read_lock(mm); |
| } |
| |
| /* |
| * If the interval [start,end) covers some unmapped address |
| * ranges, just ignore them, but return -ENOMEM at the end. |
| * - different from the way of handling in mlock etc. |
| */ |
| vma = find_vma_prev(mm, start, &prev); |
| if (vma && start > vma->vm_start) |
| prev = vma; |
| |
| blk_start_plug(&plug); |
| for (;;) { |
| /* Still start < end. */ |
| error = -ENOMEM; |
| if (!vma) |
| goto out; |
| |
| /* Here start < (end|vma->vm_end). */ |
| if (start < vma->vm_start) { |
| unmapped_error = -ENOMEM; |
| start = vma->vm_start; |
| if (start >= end) |
| goto out; |
| } |
| |
| /* Here vma->vm_start <= start < (end|vma->vm_end) */ |
| tmp = vma->vm_end; |
| if (end < tmp) |
| tmp = end; |
| |
| /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */ |
| error = madvise_vma(vma, &prev, start, tmp, behavior); |
| if (error) |
| goto out; |
| start = tmp; |
| if (prev && start < prev->vm_end) |
| start = prev->vm_end; |
| error = unmapped_error; |
| if (start >= end) |
| goto out; |
| if (prev) |
| vma = prev->vm_next; |
| else /* madvise_remove dropped mmap_lock */ |
| vma = find_vma(mm, start); |
| } |
| out: |
| blk_finish_plug(&plug); |
| if (write) |
| mmap_write_unlock(mm); |
| else |
| mmap_read_unlock(mm); |
| |
| return error; |
| } |
| |
| SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior) |
| { |
| return do_madvise(current->mm, start, len_in, behavior); |
| } |
| |
| SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec, |
| size_t, vlen, int, behavior, unsigned int, flags) |
| { |
| ssize_t ret; |
| struct iovec iovstack[UIO_FASTIOV], iovec; |
| struct iovec *iov = iovstack; |
| struct iov_iter iter; |
| struct pid *pid; |
| struct task_struct *task; |
| struct mm_struct *mm; |
| size_t total_len; |
| unsigned int f_flags; |
| |
| if (flags != 0) { |
| ret = -EINVAL; |
| goto out; |
| } |
| |
| ret = import_iovec(READ, vec, vlen, ARRAY_SIZE(iovstack), &iov, &iter); |
| if (ret < 0) |
| goto out; |
| |
| pid = pidfd_get_pid(pidfd, &f_flags); |
| if (IS_ERR(pid)) { |
| ret = PTR_ERR(pid); |
| goto free_iov; |
| } |
| |
| task = get_pid_task(pid, PIDTYPE_PID); |
| if (!task) { |
| ret = -ESRCH; |
| goto put_pid; |
| } |
| |
| if (!process_madvise_behavior_valid(behavior)) { |
| ret = -EINVAL; |
| goto release_task; |
| } |
| |
| /* Require PTRACE_MODE_READ to avoid leaking ASLR metadata. */ |
| mm = mm_access(task, PTRACE_MODE_READ_FSCREDS); |
| if (IS_ERR_OR_NULL(mm)) { |
| ret = IS_ERR(mm) ? PTR_ERR(mm) : -ESRCH; |
| goto release_task; |
| } |
| |
| /* |
| * Require CAP_SYS_NICE for influencing process performance. Note that |
| * only non-destructive hints are currently supported. |
| */ |
| if (!capable(CAP_SYS_NICE)) { |
| ret = -EPERM; |
| goto release_mm; |
| } |
| |
| total_len = iov_iter_count(&iter); |
| |
| while (iov_iter_count(&iter)) { |
| iovec = iov_iter_iovec(&iter); |
| ret = do_madvise(mm, (unsigned long)iovec.iov_base, |
| iovec.iov_len, behavior); |
| if (ret < 0) |
| break; |
| iov_iter_advance(&iter, iovec.iov_len); |
| } |
| |
| if (ret == 0) |
| ret = total_len - iov_iter_count(&iter); |
| |
| release_mm: |
| mmput(mm); |
| release_task: |
| put_task_struct(task); |
| put_pid: |
| put_pid(pid); |
| free_iov: |
| kfree(iov); |
| out: |
| return ret; |
| } |