Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754182AbYKMR2g (ORCPT ); Thu, 13 Nov 2008 12:28:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751447AbYKMR21 (ORCPT ); Thu, 13 Nov 2008 12:28:27 -0500 Received: from over.ny.us.ibm.com ([32.97.182.150]:60392 "EHLO over.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751066AbYKMR21 (ORCPT ); Thu, 13 Nov 2008 12:28:27 -0500 Subject: Re: [BUGFIX][PATCH] memory hotplug: fix notiier chain return value (Was Re: 2.6.28-rc4 mem_cgroup_charge_common panic) From: Badari Pulavarty To: KAMEZAWA Hiroyuki Cc: Andrew Morton , linux-mm , linux-kernel In-Reply-To: <20081113202758.2f12915a.kamezawa.hiroyu@jp.fujitsu.com> References: <1226353408.8805.12.camel@badari-desktop> <20081113202758.2f12915a.kamezawa.hiroyu@jp.fujitsu.com> Content-Type: text/plain Date: Thu, 13 Nov 2008 09:11:09 -0800 Message-Id: <1226596269.4835.21.camel@badari-desktop> Mime-Version: 1.0 X-Mailer: Evolution 2.22.3.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2402 Lines: 85 On Thu, 2008-11-13 at 20:27 +0900, KAMEZAWA Hiroyuki wrote: > Badari, I think you used SLUB. If so, page_cgroup's notifier callback was not > called and newly allocated page's page_cgroup wasn't allocated. > This is a fix. (notifier saw STOP_HERE flag added by slub's notifier.) No. I wasn't using SLUB. # egrep "SLUB|SLAB" .config CONFIG_SLAB=y # CONFIG_SLUB is not set CONFIG_SLABINFO=y # CONFIG_DEBUG_SLAB is not set I can test the patch and let you know. Thanks, Badari > > I'm now testing modified kernel, which does alloc/free page_cgroup by notifier. > (Usually, all page_cgroups are from bootmem and not freed. > so, modified a bit for test) > > And I cannot reproduce panic. I think you do "real" memory hotplug other than > online/offline and saw panic caused by this. > > Is this slub's behavior intentional ? page_cgroup's notifier has lower priority > than slub, now. > > Thanks, > -Kame > == > notifier callback's notifier_from_errno() just works well in error > route. (It adds mask for "stop here") > > Hanlder should return NOTIFY_OK in explict way. > > Signed-off-by:KAMEZAWA Hiroyuki > --- > mm/page_cgroup.c | 5 ++++- > mm/slub.c | 6 ++++-- > 2 files changed, 8 insertions(+), 3 deletions(-) > > Index: mmotm-2.6.28-Nov10/mm/slub.c > =================================================================== > --- mmotm-2.6.28-Nov10.orig/mm/slub.c > +++ mmotm-2.6.28-Nov10/mm/slub.c > @@ -3220,8 +3220,10 @@ static int slab_memory_callback(struct n > case MEM_CANCEL_OFFLINE: > break; > } > - > - ret = notifier_from_errno(ret); > + if (ret) > + ret = notifier_from_errno(ret); > + else > + ret = NOTIFY_OK; > return ret; > } > > Index: mmotm-2.6.28-Nov10/mm/page_cgroup.c > =================================================================== > --- mmotm-2.6.28-Nov10.orig/mm/page_cgroup.c > +++ mmotm-2.6.28-Nov10/mm/page_cgroup.c > @@ -216,7 +216,10 @@ static int page_cgroup_callback(struct n > break; > } > > - ret = notifier_from_errno(ret); > + if (ret) > + ret = notifier_from_errno(ret); > + else > + ret = NOTIFY_OK; > > return ret; > } > > -- 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/