From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756677Ab0C3XPc (ORCPT ); Tue, 30 Mar 2010 19:15:32 -0400 Received: from kroah.org ([198.145.64.141]:49286 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756616Ab0C3XNH (ORCPT ); Tue, 30 Mar 2010 19:13:07 -0400 X-Mailbox-Line: From linux@linux.site Tue Mar 30 15:59:00 2010 Message-Id: <20100330225859.499571908@linux.site> User-Agent: quilt/0.47-14.9 Date: Tue, 30 Mar 2010 15:58:24 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Ravikiran Thirumalai , KOSAKI Motohiro , Christoph Lameter , Mel Gorman , Lee Schermerhorn , Hugh Dickins , Greg Kroah-Hartman Subject: [82/89] tmpfs: fix oops on mounts with mpol=default In-Reply-To: <20100330230520.GA28779@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.31-stable review patch. If anyone has any objections, please let us know. ------------------ From: Ravikiran G Thirumalai commit 413b43deab8377819aba1dbad2abf0c15d59b491 upstream. 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 Acked-by: Lee Schermerhorn Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/mempolicy.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -2142,10 +2142,15 @@ int mpol_parse_str(char *str, struct mem 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. */ }