Date: Wed, 14 Jan 2009 14:08:35 +0530
From: Balbir Singh <balbir@linux.vnet.ibm.com>
To: Li Zefan <lizf@cn.fujitsu.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
       KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
       Paul Menage <menage@google.com>,
       Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>,
       LKML <linux-kernel@vger.kernel.org>,
       "linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH] memcg: fix return value of mem_cgroup_hierarchy_write()
Message-ID: <20090114083835.GL27129@balbir.in.ibm.com>
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* Li Zefan <lizf@cn.fujitsu.com> [2009-01-14 16:10:52]:

> When there are sub-dirs, writing to memory.use_hierarchy returns -EBUSY,
> this doesn't seem to fit the meaning of EBUSY, and is inconsistent with
> memory.swappiness, which returns -EINVAL in this case.
> 
> Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>

The patch does much more than the changelog says. The reason for EBUSY
is that the group is in use due to children or existing references and
tasks. I think EBUSY is the correct error code to return.

-- 
	Balbir
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