--- /dev/null
+/*
+ * 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/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 (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));
+ 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;
+
+#ifdef CONFIG_SWAP
+ if (!file) {
+ *prev = vma;
+ force_swapin_readahead(vma, start, end);
+ return 0;
+ }
+
+ if (shmem_mapping(file->f_mapping)) {
+ *prev = vma;
+ 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;
+ }
+
+ *prev = vma;
+ 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 | VM_HUGETLB))
+ 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 int
+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 1;
+
+ default:
+ return 0;
+ }
+}
+
+/*
+ * 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;
+}
Code Review / kvmfornfv.git / blobdiff