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- // 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:
- 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, vma_get_anon_name(vma));
- 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.
- */
- vm_write_begin(vma);
- WRITE_ONCE(vma->vm_flags, new_flags);
- vm_write_end(vma);
- 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,
- };
- vm_write_begin(vma);
- tlb_start_vma(tlb, vma);
- walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
- tlb_end_vma(tlb, vma);
- vm_write_end(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, start_addr, end_addr);
- madvise_cold_page_range(&tlb, vma, start_addr, end_addr);
- tlb_finish_mmu(&tlb, start_addr, end_addr);
- 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,
- };
- vm_write_begin(vma);
- tlb_start_vma(tlb, vma);
- walk_page_range(vma->vm_mm, addr, end, &cold_walk_ops, &walk_private);
- tlb_end_vma(tlb, vma);
- vm_write_end(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(file_inode(vma->vm_file)) ||
- inode_permission(file_inode(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, start_addr, end_addr);
- madvise_pageout_page_range(&tlb, vma, start_addr, end_addr);
- tlb_finish_mmu(&tlb, start_addr, end_addr);
- 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, range.start, range.end);
- update_hiwater_rss(mm);
- mmu_notifier_invalidate_range_start(&range);
- vm_write_begin(vma);
- 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);
- vm_write_end(vma);
- mmu_notifier_invalidate_range_end(&range);
- tlb_finish_mmu(&tlb, range.start, range.end);
- 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 splitted 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;
- }
- /*
- * 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)
- {
- struct zone *zone;
- 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;
- }
- /* Ensure that all poisoned pages are removed from per-cpu lists */
- for_each_populated_zone(zone)
- drain_all_pages(zone);
- 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);
- 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:
- #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:
- case MADV_WILLNEED:
- 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 hanppens.
- * MADV_PAGEOUT - the application is not expected to use this memory soon,
- * page out the pages in this range immediately.
- *
- * 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);
- }
- ret = (total_len - iov_iter_count(&iter)) ? : ret;
- release_mm:
- mmput(mm);
- release_task:
- put_task_struct(task);
- put_pid:
- put_pid(pid);
- free_iov:
- kfree(iov);
- out:
- return ret;
- }
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