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authorShaohua Li <shli@kernel.org>2013-02-23 04:32:31 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2013-02-24 05:50:10 +0400
commit1998cc048901109a29924380b8e91bc049b32951 (patch)
tree71c6875e8a9a6da14899f74e2dd3168d99374bd5 /mm/madvise.c
parenta394cb8ee632ec5edce20309901ec66767497a43 (diff)
downloadlinux-1998cc048901109a29924380b8e91bc049b32951.tar.xz
mm: make madvise(MADV_WILLNEED) support swap file prefetch
Make madvise(MADV_WILLNEED) support swap file prefetch. If memory is swapout, this syscall can do swapin prefetch. It has no impact if the memory isn't swapout. [akpm@linux-foundation.org: fix CONFIG_SWAP=n build] [sasha.levin@oracle.com: fix BUG on madvise early failure] Signed-off-by: Shaohua Li <shli@fusionio.com> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/madvise.c')
-rw-r--r--mm/madvise.c105
1 files changed, 101 insertions, 4 deletions
diff --git a/mm/madvise.c b/mm/madvise.c
index 03dfa5c7adb3..c58c94b56c3d 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -16,6 +16,9 @@
#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
@@ -131,6 +134,84 @@ 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) || pte_file(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_page(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.
*/
@@ -140,6 +221,18 @@ static long madvise_willneed(struct vm_area_struct * vma,
{
struct file *file = vma->vm_file;
+#ifdef CONFIG_SWAP
+ if (!file || mapping_cap_swap_backed(file->f_mapping)) {
+ *prev = vma;
+ if (!file)
+ force_swapin_readahead(vma, start, end);
+ else
+ force_shm_swapin_readahead(vma, start, end,
+ file->f_mapping);
+ return 0;
+ }
+#endif
+
if (!file)
return -EBADF;
@@ -371,6 +464,7 @@ SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
int error = -EINVAL;
int write;
size_t len;
+ struct blk_plug plug;
#ifdef CONFIG_MEMORY_FAILURE
if (behavior == MADV_HWPOISON || behavior == MADV_SOFT_OFFLINE)
@@ -410,18 +504,19 @@ SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
if (vma && start > vma->vm_start)
prev = vma;
+ blk_start_plug(&plug);
for (;;) {
/* Still start < end. */
error = -ENOMEM;
if (!vma)
- goto out;
+ goto out_plug;
/* Here start < (end|vma->vm_end). */
if (start < vma->vm_start) {
unmapped_error = -ENOMEM;
start = vma->vm_start;
if (start >= end)
- goto out;
+ goto out_plug;
}
/* Here vma->vm_start <= start < (end|vma->vm_end) */
@@ -432,18 +527,20 @@ SYSCALL_DEFINE3(madvise, unsigned long, start, size_t, len_in, int, behavior)
/* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */
error = madvise_vma(vma, &prev, start, tmp, behavior);
if (error)
- goto out;
+ goto out_plug;
start = tmp;
if (prev && start < prev->vm_end)
start = prev->vm_end;
error = unmapped_error;
if (start >= end)
- goto out;
+ goto out_plug;
if (prev)
vma = prev->vm_next;
else /* madvise_remove dropped mmap_sem */
vma = find_vma(current->mm, start);
}
+out_plug:
+ blk_finish_plug(&plug);
out:
if (write)
up_write(&current->mm->mmap_sem);