Date: Tue, 12 May 2015 10:40:32 -0400
From: Tejun Heo <tj@kernel.org>
To: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Cc: Kyungmin Park <kmpark@infradead.org>, linux-mm <linux-mm@kvack.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        "\\Rafael J. Wysocki\\" <rjw@rjwysocki.net>,
        David Rientjes <rientjes@google.com>,
        Johannes Weiner <hannes@cmpxchg.org>, Oleg Nesterov <oleg@redhat.com>,
        Cong Wang <xiyou.wangcong@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux PM list <linux-pm@vger.kernel.org>
Subject: Re: [RFC PATCH] PM, freezer: Don't thaw when it's intended frozen
 processes
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On Mon, May 11, 2015 at 03:33:10PM +0900, Krzysztof Kozlowski wrote:
> > Yes, they should and I'm not sure why what you're saying is happening
> > because freezing() test done from the frozen tasks themselves should
> > keep them in the freezer.  Which kernel version did you test?  Can you
> > please verify it against a recent kernel?
> 
> I tested it on v4.1-rc3 and next-20150508.
> 
> Task was moved to frozen cgroup:
> -----
> root@localhost:/sys/fs/cgroup/freezer/frozen# grep . *
> cgroup.clone_children:0
> cgroup.procs:2750
> freezer.parent_freezing:0
> freezer.self_freezing:1
> freezer.state:FROZEN
> notify_on_release:0
> tasks:2750
> tasks:2773
> -----
> 
> Unfortunately during system resume the process was woken up. The "if
> (frozen(p))" check was true. Is it expected behaviour?

It isn't optimal but doesn't break anything either.  Whether a task
stays in the freezer or not is solely decided by freezing() test by
the task itself.  Being woken up spuriously doesn't break anything.

Thanks.

-- 
tejun
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