From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933630AbaHHVH7 (ORCPT ); Fri, 8 Aug 2014 17:07:59 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:41270 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756704AbaHHUxV (ORCPT ); Fri, 8 Aug 2014 16:53:21 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Greg Thelen , Mike Snitzer , Kamal Mostafa Subject: [PATCH 3.13 200/259] dm bufio: fully initialize shrinker Date: Fri, 8 Aug 2014 13:40:23 -0700 Message-Id: <1407530482-4483-201-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1407530482-4483-1-git-send-email-kamal@canonical.com> References: <1407530482-4483-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.13 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.13.11.6 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Greg Thelen 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 Acked-by: Mikulas Patocka Signed-off-by: Mike Snitzer Signed-off-by: Kamal Mostafa --- drivers/md/dm-bufio.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/md/dm-bufio.c b/drivers/md/dm-bufio.c index 54bdd923..5056c45 100644 --- a/drivers/md/dm-bufio.c +++ b/drivers/md/dm-bufio.c @@ -1511,7 +1511,7 @@ 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; -- 1.9.1