[PATCH 3.14 103/122] mm: madvise: fix MADV_WILLNEED on shmem swapouts

From: Greg Kroah-Hartman
Date: Wed Nov 19 2014 - 16:33:30 EST

3.14-stable review patch. If anyone has any objections, please let me know.


From: Johannes Weiner <hannes@xxxxxxxxxxx>

commit 55231e5c898c5c03c14194001e349f40f59bd300 upstream.

MADV_WILLNEED currently does not read swapped out shmem pages back in.

Commit 0cd6144aadd2 ("mm + fs: prepare for non-page entries in page
cache radix trees") made find_get_page() filter exceptional radix tree
entries but failed to convert all find_get_page() callers that WANT
exceptional entries over to find_get_entry(). One of them is shmem swap
readahead in madvise, which now skips over any swap-out records.

Convert it to find_get_entry().

Fixes: 0cd6144aadd2 ("mm + fs: prepare for non-page entries in page cache radix trees")
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reported-by: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Mel Gorman <mgorman@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

mm/madvise.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -195,7 +195,7 @@ static void force_shm_swapin_readahead(s
for (; start < end; start += PAGE_SIZE) {
index = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff;

- page = find_get_page(mapping, index);
+ page = find_get_entry(mapping, index);
if (!radix_tree_exceptional_entry(page)) {
if (page)

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