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Subject: Re: cgroup scheduling: Adding kthreadd to a non-RT cgroup can
 deadlock the kernel
From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Nelson Elhage <nelhage@ksplice.com>
Cc: Paul Menage <menage@google.com>, Li Zefan <lizf@cn.fujitsu.com>,
        linux-kernel@vger.kernel.org
In-Reply-To: <20110105045447.GN23414@ksplice.com>
References: <20110105045447.GN23414@ksplice.com>
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Date: Wed, 05 Jan 2011 10:44:10 +0100
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On Tue, 2011-01-04 at 23:54 -0500, Nelson Elhage wrote:
> Hi,
> 
> I've found a bug where, on CONFIG_RT_GROUP_SCHED systems, adding the kthreadd
> task to a cgroup with cpu.rt_runtime_us = 0 (as some cgroup configuration
> scripts do, when they move all processes into a default cgroup), can result in
> deadlocks in the kernel.

IMHO its a bug to move kthreadd into a cgroup. Simply don't do that.