From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753490Ab3J3V6S (ORCPT ); Wed, 30 Oct 2013 17:58:18 -0400 Received: from zene.cmpxchg.org ([85.214.230.12]:33632 "EHLO zene.cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753292Ab3J3V6Q (ORCPT ); Wed, 30 Oct 2013 17:58:16 -0400 From: Johannes Weiner To: Andrew Morton Cc: Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: [patch 1/3] mm: memcg: use proper memcg in limit bypass Date: Wed, 30 Oct 2013 17:55:25 -0400 Message-Id: <1383170127-32284-2-git-send-email-hannes@cmpxchg.org> X-Mailer: git-send-email 1.8.4.2 In-Reply-To: <1383170127-32284-1-git-send-email-hannes@cmpxchg.org> References: <1383170127-32284-1-git-send-email-hannes@cmpxchg.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 84235de ("fs: buffer: move allocation failure loop into the allocator") allowed __GFP_NOFAIL allocations to bypass the limit if they fail to reclaim enough memory for the charge. Because the main test case was on a 3.2-based system, this patch missed the fact that on newer kernels the charge function needs to return root_mem_cgroup when bypassing the limit, and not NULL. This will corrupt whatever memory is at NULL + percpu pointer offset. Fix this quickly before problems are reported. Signed-off-by: Johannes Weiner --- mm/memcontrol.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 34d3ca9572d6..13a9c80d5708 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2765,10 +2765,10 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm, *ptr = memcg; return 0; nomem: - *ptr = NULL; - if (gfp_mask & __GFP_NOFAIL) - return 0; - return -ENOMEM; + if (!(gfp_mask & __GFP_NOFAIL)) { + *ptr = NULL; + return -ENOMEM; + } bypass: *ptr = root_mem_cgroup; return -EINTR; -- 1.8.4.2