Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756041AbZJ2AdJ (ORCPT ); Wed, 28 Oct 2009 20:33:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755997AbZJ2AdI (ORCPT ); Wed, 28 Oct 2009 20:33:08 -0400 Received: from fgwmail7.fujitsu.co.jp ([192.51.44.37]:34585 "EHLO fgwmail7.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755991AbZJ2AdI (ORCPT ); Wed, 28 Oct 2009 20:33:08 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 Date: Thu, 29 Oct 2009 09:30:13 +0900 From: KAMEZAWA Hiroyuki To: "linux-kernel@vger.kernel.org" Cc: "linux-mm@kvack.org" , "balbir@linux.vnet.ibm.com" , "nishimura@mxp.nes.nec.co.jp" , Lee.Schermerhorn@hp.com Subject: [BUGFIX][PATCH] memcg: fix wrong pointer initialization at page migration when memcg is disabled. Message-Id: <20091029093013.cd58f3a5.kamezawa.hiroyu@jp.fujitsu.com> Organization: FUJITSU Co. LTD. X-Mailer: Sylpheed 2.5.0 (GTK+ 2.10.14; i686-pc-mingw32) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1396 Lines: 41 Lee Schermerhorn reported that he saw bad pointer dereference in mem_cgroup_end_migration() when he disabled memcg by boot option. memcg's page migration logic works as mem_cgroup_prepare_migration(page, &ptr); do page migration mem_cgroup_end_migration(page, ptr); Now, ptr is not initialized in prepare_migration when memcg is disabled by boot option. This causes panic in end_migration. This patch fixes it. Reported-by: Lee Schermerhorn Cc: Balbir Singh Cc: Daisuke Nishimura Signed-off-by: KAMEZAWA Hiroyuki --- mm/memcontrol.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) Index: linux-2.6.32-rc5/mm/memcontrol.c =================================================================== --- linux-2.6.32-rc5.orig/mm/memcontrol.c +++ linux-2.6.32-rc5/mm/memcontrol.c @@ -1990,7 +1990,8 @@ int mem_cgroup_prepare_migration(struct struct page_cgroup *pc; struct mem_cgroup *mem = NULL; int ret = 0; - + /* this pointer will be checked at end_migration */ + *ptr = NULL; if (mem_cgroup_disabled()) return 0; -- 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/