linux-kernel - Re: bug in memcg oom-killer results in a hung syscall in another process in the same cgroup

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Message-ID: <20160712071927.GD14586@dhcp22.suse.cz>
Date:	Tue, 12 Jul 2016 09:19:27 +0200
From:	Michal Hocko <mhocko@...nel.org>
To:	Shayan Pooya <shayan@...eve.org>
Cc:	cgroups mailinglist <cgroups@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org
Subject: Re: bug in memcg oom-killer results in a hung syscall in another
 process in the same cgroup

On Mon 11-07-16 11:33:19, Shayan Pooya wrote:
> >> Could you post the stack trace of the hung oom victim? Also could you
> >> post the full kernel log?
> 
> With strace, when running 500 concurrent mem-hog tasks on the same
> kernel, 33 of them failed with:
> 
> strace: ../sysdeps/nptl/fork.c:136: __libc_fork: Assertion
> `THREAD_GETMEM (self, tid) != ppid' failed.
> 
> Which is: https://sourceware.org/bugzilla/show_bug.cgi?id=15392
> And discussed before at: https://lkml.org/lkml/2015/2/6/470 but that
> patch was not accepted.

OK, so the problem is that the oom killed task doesn't report the futex
release properly? If yes then I fail to see how that is memcg specific.
Could you try to clarify what you consider a bug again, please? I am not
really sure I understand this report.

Thanks!

-- 
Michal Hocko
SUSE Labs