From: Rafael Aquini <aquini@xxxxxxxxxx>
Subject: mm: fix page leak at nfs_symlink()
Changes committed by a0b8cab3 ("mm: remove lru parameter from
__pagevec_lru_add and remove parts of pagevec API") have introduced a call
to add_to_page_cache_lru() which causes a leak in nfs_symlink() as now the
page gets an extra refcount that is not dropped.
Jan Stancek observed and reported the leak effect while running test8 from
Connectathon Testsuite. After several iterations over the test case,
which creates several symlinks on a NFS mountpoint, the test system was
quickly getting into an out-of-memory scenario.
This patch fixes the page leak by dropping that extra refcount
add_to_page_cache_lru() is grabbing.
Signed-off-by: Jan Stancek <jstancek@xxxxxxxxxx>
Signed-off-by: Rafael Aquini <aquini@xxxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxx>
Acked-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Jeff Layton <jlayton@xxxxxxxxxx>
Cc: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [3.11.x+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/nfs/dir.c | 5 +++++
1 file changed, 5 insertions(+)
diff -puN fs/nfs/dir.c~mm-fix-page-leak-at-nfs_symlink fs/nfs/dir.c
--- a/fs/nfs/dir.c~mm-fix-page-leak-at-nfs_symlink
+++ a/fs/nfs/dir.c
@@ -1846,6 +1846,11 @@ int nfs_symlink(struct inode *dir, struc
GFP_KERNEL)) {
SetPageUptodate(page);
unlock_page(page);
+ /*
+ * add_to_page_cache_lru() grabs an extra page refcount.
+ * Drop it here to avoid leaking this page later.
+ */
+ page_cache_release(page);
} else
__free_page(page);
_
--
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