linux-kernel - Re: cgroup: rmdir() does not complete

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Date:	Thu, 9 Sep 2010 11:01:45 +0100 (BST)
From:	Mark Hills <mark@...o.org.uk>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
cc:	Daisuke Nishimura <nishimura@....nes.nec.co.jp>,
	linux-kernel@...r.kernel.org, balbir@...ux.vnet.ibm.com
Subject: Re: cgroup: rmdir() does not complete

On Thu, 2 Sep 2010, KAMEZAWA Hiroyuki wrote:

[...]
> But hmm...it's curious who holds mutex and what happens.

I have a system showing the failure case (but still do not have a way to 
reliably repeat it)

Here are the two processes:

23586 pts/0    RL+  5059:18 /net/homes/mhills/tmp/soaked-cgroup
23685 pts/6    DL+    0:00 /net/homes/mhills/tmp/soaked-cgroup

23586 spends almost all of its time in 'RL+' status, occasionally it is 
seen in 'DL+' status.

>From my analysis before, both are blocked on rmdir(), but one is spinning, 
holding the lock on the /cgroup, and the other is waiting for the lock. If 
I strace 23586 then the rmdir() fails with EINTR.

How best to capture information which might show why the process spins?

-- 
Mark
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