From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753968Ab0CQOQr (ORCPT ); Wed, 17 Mar 2010 10:16:47 -0400 Received: from g1t0027.austin.hp.com ([15.216.28.34]:29882 "EHLO g1t0027.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752548Ab0CQOQp (ORCPT ); Wed, 17 Mar 2010 10:16:45 -0400 Subject: Re: [PATCH 1/5] tmpfs: fix oops on mounts with mpol=default From: Lee Schermerhorn To: KOSAKI Motohiro Cc: LKML , kiran@scalex86.org, cl@linux-foundation.org, hugh.dickins@tiscali.co.uk, mel@csn.ul.ie, stable@kernel.org, linux-mm , akpm@linux-foundation.org In-Reply-To: <20100316144810.4C48.A69D9226@jp.fujitsu.com> References: <201003122353.o2CNrC56015250@imap1.linux-foundation.org> <20100316143406.4C45.A69D9226@jp.fujitsu.com> <20100316144810.4C48.A69D9226@jp.fujitsu.com> Content-Type: text/plain Organization: HP/LKTT Date: Wed, 17 Mar 2010 10:16:11 -0400 Message-Id: <1268835371.4773.40.camel@useless.americas.hpqcorp.net> Mime-Version: 1.0 X-Mailer: Evolution 2.26.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2010-03-16 at 14:49 +0900, KOSAKI Motohiro wrote: > 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: Acked-by: Lee Schermerhorn > --- > 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. > */ > } >