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Date: Wed, 21 May 2008 21:19:58 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: linux-mm@kvack.org, Sudhir Kumar <skumar@linux.vnet.ibm.com>,
       YAMAMOTO Takashi <yamamoto@valinux.co.jp>,
       Paul Menage <menage@google.com>, lizf@cn.fujitsu.com,
       linux-kernel@vger.kernel.org, Pavel Emelianov <xemul@openvz.org>,
       KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [-mm][PATCH 3/4] cgroup mm owner callback changes to add task
 info (v5)
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On Wed, 21 May 2008 20:59:59 +0530 Balbir Singh <balbir@linux.vnet.ibm.com> wrote:

> 
> This patch adds an additional field to the mm_owner callbacks. This field
> is required to get to the mm that changed. Hold mmap_sem in write mode
> before calling the mm_owner_changed callback
>
> ...
>
> + * The callbacks are invoked with mmap_sem held in read mode.

Is that true?

> +	down_write(&mm->mmap_sem);
> ...
>  	cgroup_mm_owner_callbacks(mm->owner, c);

Looks like write-mode to me?