From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id 6633D6B0055 for ; Tue, 21 Apr 2009 04:46:07 -0400 (EDT) Received: from d28relay02.in.ibm.com (d28relay02.in.ibm.com [9.184.220.59]) by e28smtp05.in.ibm.com (8.13.1/8.13.1) with ESMTP id n3L8kjTe030480 for ; Tue, 21 Apr 2009 14:16:45 +0530 Received: from d28av03.in.ibm.com (d28av03.in.ibm.com [9.184.220.65]) by d28relay02.in.ibm.com (8.13.8/8.13.8/NCO v9.2) with ESMTP id n3L8ga0l3657812 for ; Tue, 21 Apr 2009 14:12:36 +0530 Received: from d28av03.in.ibm.com (loopback [127.0.0.1]) by d28av03.in.ibm.com (8.13.1/8.13.3) with ESMTP id n3L8kjmh008492 for ; Tue, 21 Apr 2009 18:46:45 +1000 Date: Tue, 21 Apr 2009 14:15:58 +0530 From: Balbir Singh 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> Sender: owner-linux-mm@kvack.org To: Johannes Weiner Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: * 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, 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