From: Rusty Russell <rusty@rustcorp.com.au>
To: Tejun Heo <tj@kernel.org>, Li Zefan <lizefan@huawei.com>
Cc: Tommi Rantala <tt.rantala@gmail.com>,
        containers@lists.linux-foundation.org, cgroups@vger.kernel.org,
        LKML <linux-kernel@vger.kernel.org>, Dave Jones <davej@redhat.com>
Subject: Re: cgroup_release_agent() hung task warnings
In-Reply-To: <20130304173358.GB30413@htj.dyndns.org>
References: <CA+ydwtrRAf5VW_iZYOjzmTv6Y0ebprXw_RfWVmR1okQOxQx=CA@mail.gmail.com> <51340E2E.4070805@huawei.com> <20130304173358.GB30413@htj.dyndns.org>
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Date: Tue, 05 Mar 2013 12:28:04 +1100
Message-ID: <87d2ved49n.fsf@rustcorp.com.au>
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Tejun Heo <tj@kernel.org> writes:
> (cc'ing Rusty Russell)
>
> On Mon, Mar 04, 2013 at 10:59:58AM +0800, Li Zefan wrote:
>> On 2013/3/3 3:23, Tommi Rantala wrote:
>> > Hello,
>> > 
>> > I'm seeing the following hung task warnings when fuzzing the kernel
>> > with trinity (in a qemu virtual machine, as the root user), that I
>> > have not seen before with 3.8 or earlier. The kernel is
>> > b0af9cd9aab60ceb17d3ebabb9fdf4ff0a99cf50 (Merge tag
>> > 'lzo-update-signature-20130226' of
>> > git://github.com/markus-oberhumer/linux).
>> > 
>> 
>> This doesn't look like a cgroup bug.
>
> Yes, it looks like a problem in usermodehelper.  Rusty, it looks like
> usermodehelper can jam with OOM killer going wild.  Any ideas?  The
> original report is at
>
>   https://lkml.org/lkml/2013/3/2/126

Is it really stuck, or just v. v. slow as it thrashes?

Like Tejun, I can't see how it would really get stuck...

Cheers,
Rusty.
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