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authorGreg Thelen <gthelen@google.com>2014-07-31 09:07:19 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-08-07 16:53:52 -0700
commit71881a3da0c57eb873317ac0176992cd945b5ca6 (patch)
tree0a9b4c4d980ac02642da85a1c56a047fc3228d35
parent49ab5de52b88d5e3a06c55aa07594e798c6eb9cc (diff)
downloadlwn-71881a3da0c57eb873317ac0176992cd945b5ca6.tar.gz
lwn-71881a3da0c57eb873317ac0176992cd945b5ca6.zip
dm bufio: fully initialize shrinker
commit d8c712ea471ce7a4fd1734ad2211adf8469ddddc upstream. 1d3d4437eae1 ("vmscan: per-node deferred work") added a flags field to struct shrinker assuming that all shrinkers were zero filled. The dm bufio shrinker is not zero filled, which leaves arbitrary kmalloc() data in flags. So far the only defined flags bit is SHRINKER_NUMA_AWARE. But there are proposed patches which add other bits to shrinker.flags (e.g. memcg awareness). Rather than simply initializing the shrinker, this patch uses kzalloc() when allocating the dm_bufio_client to ensure that the embedded shrinker and any other similar structures are zeroed. This fixes theoretical over aggressive shrinking of dm bufio objects. If the uninitialized dm_bufio_client.shrinker.flags contains SHRINKER_NUMA_AWARE then shrink_slab() would call the dm shrinker for each numa node rather than just once. This has been broken since 3.12. Signed-off-by: Greg Thelen <gthelen@google.com> Acked-by: Mikulas Patocka <mpatocka@redhat.com> Signed-off-by: Mike Snitzer <snitzer@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/md/dm-bufio.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c
index 66c5d130c8c2..0e722c103562 100644
--- a/drivers/md/dm-bufio.c
+++ b/drivers/md/dm-bufio.c
@@ -1541,7 +1541,7 @@ struct dm_bufio_client *dm_bufio_client_create(struct block_device *bdev, unsign
BUG_ON(block_size < 1 << SECTOR_SHIFT ||
(block_size & (block_size - 1)));
- c = kmalloc(sizeof(*c), GFP_KERNEL);
+ c = kzalloc(sizeof(*c), GFP_KERNEL);
if (!c) {
r = -ENOMEM;
goto bad_client;