Date: Sun, 27 Jul 2008 23:37:46 -0500
From: Paul Jackson <pj@sgi.com>
To: Li Zefan <lizf@cn.fujitsu.com>
Cc: akpm@linux-foundation.org, menage@google.com,
       seto.hidetoshi@jp.fujitsu.com, laijs@cn.fujitsu.com,
       linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] cpuset: clean up cpuset hierarchy traversal code
Message-Id: <20080727233746.7f057e74.pj@sgi.com>
In-Reply-To: <488D332A.1030008@cn.fujitsu.com>
References: <488D332A.1030008@cn.fujitsu.com>
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Li Zefan wrote:
> +	list_add(&top_cpuset.stack_list, &q);

Can you figure out if we are holding any system wide lock, such as
cgroup_mutex, at this point?  There is only one top_cpuset.stack_list
in the system, so I would think that we need to single thread its usage
somehow.

The hotplug hooks, such as common_cpu_mem_hotplug_unplug() that were
added sometime in the last few months (while the so called maintainer,
who's initials seem to be 'pj', was asleep ;) don't describe what
locking applies to them very well, and they call rebuild_sched_domains(),
where the above line of code lives.

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@sgi.com> 1.940.382.4214
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