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

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Date:   Thu, 26 Jan 2017 17:18:58 -0600
From:   Trevor Cordes <trevor@...nopolis.ca>
To:     Michal Hocko <mhocko@...nel.org>
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 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.

On 2017-01-25 Michal Hocko wrote:
> On Wed 25-01-17 04:02:46, Trevor Cordes wrote:
> > OK, I patched & compiled mhocko's git tree from the other day
> > 4.9.0+. (To confirm, weird, but mhocko's git tree I'm using from a
> > couple of weeks ago shows the newest commit (git log) is
> > 69973b830859bc6529a7a0468ba0d80ee5117826 "Linux 4.9"?  Let me know
> > if I'm doing something wrong, see below.)  
> 
> My fault. I should have noted that you should use since-4.9 branch.

OK, I got it now, I'm retesting the runs I did (with/without the
various patches) on your git tree and will re-report the (correct)
results.  Will take a few days.  Thanks!

Download attachment "oom6" of type "application/octet-stream" (23915 bytes)