Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756035AbZDUIrP (ORCPT ); Tue, 21 Apr 2009 04:47:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754549AbZDUIq5 (ORCPT ); Tue, 21 Apr 2009 04:46:57 -0400 Received: from e28smtp02.in.ibm.com ([59.145.155.2]:44105 "EHLO e28smtp02.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752852AbZDUIq4 (ORCPT ); Tue, 21 Apr 2009 04:46:56 -0400 Date: Tue, 21 Apr 2009 14:15:58 +0530 From: Balbir Singh To: Johannes Weiner Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [patch 1/3] mm: fix pageref leak in do_swap_page() Message-ID: <20090421084558.GC19637@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <1240259085-25872-1-git-send-email-hannes@cmpxchg.org> <20090421031419.GB30001@balbir.in.ibm.com> <20090421081903.GA2527@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20090421081903.GA2527@cmpxchg.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1396 Lines: 40 * Johannes Weiner [2009-04-21 10:19:03]: > On Tue, Apr 21, 2009 at 08:44:20AM +0530, Balbir Singh wrote: > > * Johannes Weiner [2009-04-20 22:24:43]: > > > > > By the time the memory cgroup code is notified about a swapin we > > > already hold a reference on the fault page. > > > > > > If the cgroup callback fails make sure to unlock AND release the page > > > or we leak the reference. > > > > > > Signed-off-by: Johannes Weiner > > > Cc: Balbir Singh > > > > Seems reasonable to me, could you make the changelog more verbose and > > mention that lookup_swap_cache() gets a reference to the page and we > > need to release the extra reference. > > Okay, I will add that information. > Thanks > > BTW, have you had any luck reproducing the issue? How did you catch > > the problem? > > I reviewed all the exit points when I shuffled code around in there > for another series that uses a lighter version of do_wp_page() for > swap write-faults. I never triggered that problem. > Good way of catching a problem, play with the code :) -- Balbir -- 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/