linux-kernel - Re: mm, vmscan: commit makes PAE kernel crash nightly (bisected)

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Date:   Fri, 27 Jan 2017 08:36:31 +0100
From:   Michal Hocko <mhocko@...nel.org>
To:     Trevor Cordes <trevor@...nopolis.ca>
Cc:     Mel Gorman <mgorman@...hsingularity.net>,
        linux-kernel@...r.kernel.org, Joonsoo Kim <iamjoonsoo.kim@....com>,
        Minchan Kim <minchan@...nel.org>,
        Rik van Riel <riel@...riel.com>,
        Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Subject: Re: mm, vmscan: commit makes PAE kernel crash nightly (bisected)

On Thu 26-01-17 17:18:58, Trevor Cordes wrote:
> On 2017-01-24 Michal Hocko wrote:
> > On Sun 22-01-17 18:45:59, Trevor Cordes wrote:
> > [...]
> > > Also, completely separate from your patch I ran mhocko's 4.9 tree
> > > with mem=2G to see if lower ram amount would help, but it didn't.
> > > Even with 2G the system oom and hung same as usual.  So far the
> > > only thing that helps at all was the cgroup_disable=memory option,
> > > which makes the problem disappear completely for me.  
> > 
> > OK, can we reduce the problem space slightly more and could you boot
> > with kmem accounting enabled? cgroup.memory=nokmem,nosocket
> 
> I ran for 30 hours with cgroup.memory=nokmem,nosocket using vanilla
> 4.9.0+ and it oom'd during a big rdiff-backup at 9am.  My script was
> able to reboot it before it hung.  Only one oom occurred before the
> reboot, which is a bit odd, usually there is 5-50.  See attached
> messages log (oom6).
> 
> So, still, only cgroup_disable=memory mitigates this bug (so far).  If
> you need me to test cgroup.memory=nokmem,nosocket with your since-4.9
> branch specifically, let me know and I'll add it to the to-test list.

OK, that matches the theory that these OOMs are caused by the incorrect
active list aging fixed by b4536f0c829c ("mm, memcg: fix the active list
aging for lowmem requests when memcg is enabled")
-- 
Michal Hocko
SUSE Labs