| /* |
| * 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/hugetlb.h> |
| #include <linux/falloc.h> |
| #include <linux/sched.h> |
| #include <linux/ksm.h> |
| #include <linux/fs.h> |
| #include <linux/file.h> |
| #include <linux/blkdev.h> |
| #include <linux/backing-dev.h> |
| #include <linux/swap.h> |
| #include <linux/swapops.h> |
| |
| /* |
| * Any behaviour which results in changes to the vma->vm_flags needs to |
| * take mmap_sem 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: |
| 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_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; |
| break; |
| case MADV_HUGEPAGE: |
| case MADV_NOHUGEPAGE: |
| error = hugepage_madvise(vma, &new_flags, behavior); |
| if (error) |
| goto out; |
| 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) { |
| error = split_vma(mm, vma, start, 1); |
| if (error) |
| goto out; |
| } |
| |
| if (end != vma->vm_end) { |
| error = split_vma(mm, vma, end, 0); |
| if (error) |
| goto out; |
| } |
| |
| success: |
| /* |
| * vm_flags is protected by the mmap_sem held in write mode. |
| */ |
| vma->vm_flags = new_flags; |
| |
| out: |
| if (error == -ENOMEM) |
| error = -EAGAIN; |
| 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); |
| if (page) |
| page_cache_release(page); |
| } |
| |
| return 0; |
| } |
| |
| static void force_swapin_readahead(struct vm_area_struct *vma, |
| unsigned long start, unsigned long end) |
| { |
| struct mm_walk walk = { |
| .mm = vma->vm_mm, |
| .pmd_entry = swapin_walk_pmd_entry, |
| .private = vma, |
| }; |
| |
| walk_page_range(start, end, &walk); |
| |
| lru_add_drain(); /* Push any new pages onto the LRU now */ |
| } |
| |
| static void force_shm_swapin_readahead(struct vm_area_struct *vma, |
| unsigned long start, unsigned long end, |
| struct address_space *mapping) |
| { |
| pgoff_t index; |
| struct page *page; |
| swp_entry_t swap; |
| |
| for (; start < end; start += PAGE_SIZE) { |
| index = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; |
| |
| page = find_get_entry(mapping, index); |
| if (!radix_tree_exceptional_entry(page)) { |
| if (page) |
| page_cache_release(page); |
| continue; |
| } |
| swap = radix_to_swp_entry(page); |
| page = read_swap_cache_async(swap, GFP_HIGHUSER_MOVABLE, |
| NULL, 0); |
| if (page) |
| page_cache_release(page); |
| } |
| |
| 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 file *file = vma->vm_file; |
| |
| *prev = vma; |
| #ifdef CONFIG_SWAP |
| if (!file) { |
| force_swapin_readahead(vma, start, end); |
| 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; |
| } |
| |
| start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; |
| if (end > vma->vm_end) |
| end = vma->vm_end; |
| end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; |
| |
| force_page_cache_readahead(file->f_mapping, file, start, end - start); |
| 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(struct vm_area_struct *vma, |
| struct vm_area_struct **prev, |
| unsigned long start, unsigned long end) |
| { |
| *prev = vma; |
| if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP)) |
| return -EINVAL; |
| |
| zap_page_range(vma, start, end - start, NULL); |
| 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; |
| |
| *prev = NULL; /* tell sys_madvise we drop mmap_sem */ |
| |
| 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_sem. |
| */ |
| get_file(f); |
| up_read(¤t->mm->mmap_sem); |
| error = vfs_fallocate(f, |
| FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, |
| offset, end - start); |
| fput(f); |
| down_read(¤t->mm->mmap_sem); |
| return error; |
| } |
| |
| #ifdef CONFIG_MEMORY_FAILURE |
| /* |
| * Error injection support for memory error handling. |
| */ |
| static int madvise_hwpoison(int bhv, unsigned long start, unsigned long end) |
| { |
| struct page *p; |
| if (!capable(CAP_SYS_ADMIN)) |
| return -EPERM; |
| for (; start < end; start += PAGE_SIZE << |
| compound_order(compound_head(p))) { |
| int ret; |
| |
| ret = get_user_pages_fast(start, 1, 0, &p); |
| if (ret != 1) |
| return ret; |
| |
| if (PageHWPoison(p)) { |
| put_page(p); |
| continue; |
| } |
| if (bhv == MADV_SOFT_OFFLINE) { |
| pr_info("Soft offlining page %#lx at %#lx\n", |
| page_to_pfn(p), start); |
| ret = soft_offline_page(p, MF_COUNT_INCREASED); |
| if (ret) |
| return ret; |
| continue; |
| } |
| pr_info("Injecting memory failure for page %#lx at %#lx\n", |
| page_to_pfn(p), start); |
| /* Ignore return value for now */ |
| memory_failure(page_to_pfn(p), 0, MF_COUNT_INCREASED); |
| } |
| 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_DONTNEED: |
| return madvise_dontneed(vma, prev, start, end); |
| 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: |
| #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: |
| 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_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_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. |
| * |
| * 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. |
| * -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. |
| */ |
| SYSCALL_DEFINE3(madvise, 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; |
| |
| #ifdef CONFIG_MEMORY_FAILURE |
| if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE) |
| return madvise_hwpoison(behavior, start, start+len_in); |
| #endif |
| if (!madvise_behavior_valid(behavior)) |
| return error; |
| |
| if (start & ~PAGE_MASK) |
| return error; |
| len = (len_in + ~PAGE_MASK) & PAGE_MASK; |
| |
| /* 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; |
| |
| write = madvise_need_mmap_write(behavior); |
| if (write) |
| down_write(¤t->mm->mmap_sem); |
| else |
| down_read(¤t->mm->mmap_sem); |
| |
| /* |
| * 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(current->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_sem */ |
| vma = find_vma(current->mm, start); |
| } |
| out: |
| blk_finish_plug(&plug); |
| if (write) |
| up_write(¤t->mm->mmap_sem); |
| else |
| up_read(¤t->mm->mmap_sem); |
| |
| return error; |
| } |