Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752122AbaGaQH1 (ORCPT ); Thu, 31 Jul 2014 12:07:27 -0400 Received: from mail-qa0-f74.google.com ([209.85.216.74]:65367 "EHLO mail-qa0-f74.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751066AbaGaQHY (ORCPT ); Thu, 31 Jul 2014 12:07:24 -0400 From: Greg Thelen To: Alasdair Kergon , Mike Snitzer , dm-devel@redhat.com Cc: Neil Brown , Andrew Morton , Vladimir Davydov , Dave Chinner , linux-raid@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Greg Thelen Subject: [PATCH] dm bufio: fully initialize shrinker Date: Thu, 31 Jul 2014 09:07:19 -0700 Message-Id: <1406822839-2423-1-git-send-email-gthelen@google.com> X-Mailer: git-send-email 2.0.0.526.g5318336 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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 4e84095833db..d724459860d9 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; -- 2.0.0.526.g5318336 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/