linux-kernel - Re: [PATCH for 3.2] memcg: do not trap chargers with full callstack on OOM

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Date:	Fri, 5 Jul 2013 14:17:28 -0400
From:	Johannes Weiner <hannes@...xchg.org>
To:	azurIt <azurit@...ox.sk>
Cc:	Michal Hocko <mhocko@...e.cz>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, cgroups mailinglist <cgroups@...r.kernel.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [PATCH for 3.2] memcg: do not trap chargers with full callstack
 on OOM

Hi azurIt,

On Fri, Jun 28, 2013 at 12:06:13PM +0200, azurIt wrote:
> >It's not a kernel thread that does it because all kernel-context
> >handle_mm_fault() are annotated properly, which means the task must be
> >userspace and, since tasks is empty, have exited before synchronizing.
> >
> >Can you try with the following patch on top?
> 
> 
> Michal and Johannes,
> 
> i have some observations which i made: Original patch from Johannes
> was really fixing something but definitely not everything and was
> introducing new problems. I'm running unpatched kernel from time i
> send my last message and problems with freezing cgroups are occuring
> very often (several times per day) - they were, on the other hand,
> quite rare with patch from Johannes.

That's good!

> Johannes, i didn't try your last patch yet. I would like to wait
> until you or Michal look at my last message which contained detailed
> information about freezing of cgroups on kernel running your
> original patch (which was suppose to fix it for good). Even more, i
> would like to hear your opinion about that stucked processes which
> was holding web server port and which forced me to reboot production
> server at the middle of the day :( more information was in my last
> message. Thank you very much for your time.

I looked at your debug messages but could not find anything that would
hint at a deadlock.  All tasks are stuck in the refrigerator, so I
assume you use the freezer cgroup and enabled it somehow?

Sorry about your production server locking up, but from the stacks I
don't see any connection to the OOM problems you were having... :/
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