Message-ID: <50939A82.8080203@jp.fujitsu.com>
Date: Fri, 02 Nov 2012 19:03:46 +0900
From: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
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To: Tejun Heo <tj@kernel.org>
CC: lizefan@huawei.com, hannes@cmpxchg.org, mhocko@suse.cz,
        bsingharora@gmail.com, containers@lists.linux-foundation.org,
        cgroups@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 3/8] cgroup: use cgroup_lock_live_group(parent) in cgroup_create()
References: <1351712650-23709-1-git-send-email-tj@kernel.org> <1351712650-23709-4-git-send-email-tj@kernel.org>
In-Reply-To: <1351712650-23709-4-git-send-email-tj@kernel.org>
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(2012/11/01 4:44), Tejun Heo wrote:
> This patch makes cgroup_create() fail if @parent is marked removed.
> This is to prepare for further updates to cgroup_rmdir() path.
> 
> Note that this change isn't strictly necessary.  cgroup can only be
> created via mkdir and the removed marking and dentry removal happen
> without releasing cgroup_mutex, so cgroup_create() can never race with
> cgroup_rmdir().  Even after the scheduled updates to cgroup_rmdir(),
> cgroup_mkdir() and cgroup_rmdir() are synchronized by i_mutex
> rendering the added liveliness check unnecessary.
> 
> Do it anyway such that locking is contained inside cgroup proper and
> we don't get nasty surprises if we ever grow another caller of
> cgroup_create().
> 
> Signed-off-by: Tejun Heo <tj@kernel.org>
> Reviewed-by: Michal Hocko <mhocko@suse.cz>

Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>


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