From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752120AbdAMPvs (ORCPT ); Fri, 13 Jan 2017 10:51:48 -0500 Received: from mx2.suse.de ([195.135.220.15]:53354 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752098AbdAMPvq (ORCPT ); Fri, 13 Jan 2017 10:51:46 -0500 Date: Fri, 13 Jan 2017 16:51:42 +0100 From: Michal Hocko To: Vlastimil Babka Cc: Ganapatrao Kulkarni , linux-mm@kvack.org, "linux-kernel@vger.kernel.org" , Mel Gorman Subject: Re: getting oom/stalls for ltp test cpuset01 with latest/4.9 kernel Message-ID: <20170113155142.GO25212@dhcp22.suse.cz> References: <075075cc-3149-0df3-dd45-a81df1f1a506@suse.cz> <0ea1cfeb-7c4a-3a3e-9be9-967298ba303c@suse.cz> <20170111164616.GJ16365@dhcp22.suse.cz> <45ed555a-c6a3-fc8e-1e87-c347c8ed086b@suse.cz> <89fec1bd-52b7-7861-2e02-a719c5631610@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <89fec1bd-52b7-7861-2e02-a719c5631610@suse.cz> User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 13-01-17 10:06:14, Vlastimil Babka wrote: [...] > >From 9f041839401681f2678edf5040c851d11963c5fe Mon Sep 17 00:00:00 2001 > From: Vlastimil Babka > Date: Fri, 13 Jan 2017 10:01:26 +0100 > Subject: [PATCH] mm, page_alloc: fix race with cpuset update or removal > > Changelog and S-O-B TBD. > --- > mm/page_alloc.c | 10 +++++++++- > 1 file changed, 9 insertions(+), 1 deletion(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 6de9440e3ae2..c397f146843a 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -3775,9 +3775,17 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, > /* > * Restore the original nodemask if it was potentially replaced with > * &cpuset_current_mems_allowed to optimize the fast-path attempt. > + * Also recalculate the starting point for the zonelist iterator or > + * we could end up iterating over non-eligible zones endlessly. > */ > - if (cpusets_enabled()) > + if (unlikely(ac.nodemask != nodemask)) { > ac.nodemask = nodemask; > + ac.preferred_zoneref = first_zones_zonelist(ac.zonelist, > + ac.high_zoneidx, ac.nodemask); > + if (!ac.preferred_zoneref) > + goto no_zone; > + } > + > page = __alloc_pages_slowpath(alloc_mask, order, &ac); I think you nailed it. It is really possible that preferred_zoneref is outside of the cpuset_current_mems_allowed and if we are unlucky there won't be any other zones on the zonelist... -- Michal Hocko SUSE Labs