From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757320Ab0CPFtc (ORCPT ); Tue, 16 Mar 2010 01:49:32 -0400 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:58450 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757199Ab0CPFtb (ORCPT ); Tue, 16 Mar 2010 01:49:31 -0400 X-SecurityPolicyCheck-FJ: OK by FujitsuOutboundMailChecker v1.3.1 From: KOSAKI Motohiro To: LKML Subject: [PATCH 1/5] tmpfs: fix oops on mounts with mpol=default Cc: kosaki.motohiro@jp.fujitsu.com, kiran@scalex86.org, cl@linux-foundation.org, hugh.dickins@tiscali.co.uk, lee.schermerhorn@hp.com, mel@csn.ul.ie, stable@kernel.org, linux-mm , akpm@linux-foundation.org In-Reply-To: <20100316143406.4C45.A69D9226@jp.fujitsu.com> References: <201003122353.o2CNrC56015250@imap1.linux-foundation.org> <20100316143406.4C45.A69D9226@jp.fujitsu.com> Message-Id: <20100316144810.4C48.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: Becky! ver. 2.50.07 [ja] Date: Tue, 16 Mar 2010 14:49:28 +0900 (JST) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ChangeLog from Ravikiran's original one - Fix the patch description. the problem is in mount, not only remount. - Skip mpol_new() simply, instead adding NULL check. ========================= From: Ravikiran G Thirumalai Fix an 'oops' when a tmpfs mount point is mounted with the mpol=default mempolicy. Upon remounting a tmpfs mount point with 'mpol=default' option, the mount code crashed with a null pointer dereference. The initial problem report was on 2.6.27, but the problem exists in mainline 2.6.34-rc as well. On examining the code, we see that mpol_new returns NULL if default mempolicy was requested. This 'NULL' mempolicy is accessed to store the node mask resulting in oops. The following patch fixes it. Signed-off-by: Ravikiran Thirumalai Signed-off-by: KOSAKI Motohiro Cc: Christoph Lameter Cc: Mel Gorman Cc: Lee Schermerhorn Cc: Hugh Dickins Cc: --- mm/mempolicy.c | 9 +++++++-- 1 files changed, 7 insertions(+), 2 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index bda230e..25a0c0f 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -2213,10 +2213,15 @@ int mpol_parse_str(char *str, struct mempolicy **mpol, int no_context) goto out; mode = MPOL_PREFERRED; break; - + case MPOL_DEFAULT: + /* + * Insist on a empty nodelist + */ + if (!nodelist) + err = 0; + goto out; /* * case MPOL_BIND: mpol_new() enforces non-empty nodemask. - * case MPOL_DEFAULT: mpol_new() enforces empty nodemask, ignores flags. */ } -- 1.6.5.2