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Date: Wed, 31 Oct 2012 13:11:02 -0700
Message-ID: <CAOS58YPbYoMJ1+3uRfK_ZERyZoaby=FPW7uTpp8dVOSgYC8Mrw@mail.gmail.com>
Subject: Re: [PATCH 1/8] cgroup: kill cgroup_subsys->__DEPRECATED_clear_css_refs
From: Tejun Heo <tj@kernel.org>
To: Michal Hocko <mhocko@suse.cz>
Cc: lizefan@huawei.com, hannes@cmpxchg.org, bsingharora@gmail.com,
        kamezawa.hiroyu@jp.fujitsu.com, containers@lists.linux-foundation.org,
        cgroups@vger.kernel.org, linux-kernel@vger.kernel.org
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Hello,

On Wed, Oct 31, 2012 at 1:08 PM, Michal Hocko <mhocko@suse.cz> wrote:
> local_irq_disable doesn't guarantee atomicity, because other CPUs will

Maybe it should say atomicity on the local CPU.

> see the change in steps so this is a bit misleading. The real reason
> AFAICS is that we do not want to hang in css_tryget from IRQ context
> (does this really happen btw.?) which would interrupt cgroup_rmdir
> between we add CSS_DEACT_BIAS and the group is marked CGRP_REMOVED.
> Or am I still missing the point?

Yeah, that's the correct one. We don't want tryget happening between
DEACT_BIAS and REMOVED as it can hang forever there.

Thanks.

-- 
tejun
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