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

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Date:	Sat, 22 Jun 2013 22:09:58 +0200
From:	"azurIt" <azurit@...ox.sk>
To:	Michal Hocko <mhocko@...e.cz>
Cc:	<linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
	cgroups mailinglist <cgroups@...r.kernel.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Johannes Weiner <hannes@...xchg.org>
Subject: Re: [PATCH for 3.2] memcg: do not trap chargers with full callstack on OOM

Michal,

>> I'm unable to send you stacks or more info because problem is taking
>> down the whole server for some time now (don't know what exactly
>> caused it to start happening, maybe newer versions of 3.2.x).
>
>So you are not testing with the same kernel with just the old patch
>replaced by the new one?

No, i'm not testing with the same kernel but all are 3.2.x. I even cannot install older 3.2.x because grsecurity is always available for newest kernel and there is no archive of older versions (at least i don't know about any).

>> But i'm sure of one thing - when problem occurs, nothing is able to
>> access hard drives (every process which tries it is freezed until
>> problem is resolved or server is rebooted).
>
>I would be really interesting to see what those tasks are blocked on.

I'm trying to get it, stay tuned :)

Today i noticed one bug, not 100% sure it is related to 'your' patch but i didn't seen this before. I noticed that i have lots of cgroups which cannot be removed - if i do 'rmdir <cgroup_directory>', it just hangs and never complete. Even more, it's not possible to access the whole cgroup filesystem until i kill that rmdir (anything, which tries it, just hangs). All unremoveable cgroups has this in 'memory.oom_control':
oom_kill_disable 0
under_oom 1

And, yes, 'tasks' file is empty.

azur
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