From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail202.messagelabs.com (mail202.messagelabs.com [216.82.254.227]) by kanga.kvack.org (Postfix) with SMTP id 98AAC6B004D for ; Wed, 28 Oct 2009 20:33:11 -0400 (EDT) Received: from m2.gw.fujitsu.co.jp ([10.0.50.72]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id n9T0X9Un017297 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Thu, 29 Oct 2009 09:33:09 +0900 Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 4DADF45DE4E for ; Thu, 29 Oct 2009 09:33:09 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id 2A4C345DE51 for ; Thu, 29 Oct 2009 09:33:09 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 13BC01DB803A for ; Thu, 29 Oct 2009 09:33:09 +0900 (JST) Received: from m108.s.css.fujitsu.com (m108.s.css.fujitsu.com [10.249.87.108]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 845EB1DB8038 for ; Thu, 29 Oct 2009 09:33:08 +0900 (JST) Date: Thu, 29 Oct 2009 09:30:13 +0900 From: KAMEZAWA Hiroyuki Subject: [BUGFIX][PATCH] memcg: fix wrong pointer initialization at page migration when memcg is disabled. Message-Id: <20091029093013.cd58f3a5.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org 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 List-ID: 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org