linux-kernel - Re: [Patch v3 1/2] freezer: check OOM kill while being frozen

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Date:	Tue, 2 Sep 2014 15:52:40 -0700
From:	Cong Wang <xiyou.wangcong@...il.com>
To:	Tejun Heo <tj@...nel.org>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	David Rientjes <rientjes@...gle.com>,
	Michal Hocko <mhocko@...e.cz>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [Patch v3 1/2] freezer: check OOM kill while being frozen

On Sat, Aug 16, 2014 at 5:20 AM, Tejun Heo <tj@...nel.org> wrote:
> On Thu, Aug 14, 2014 at 02:15:25PM -0700, Cong Wang wrote:
>> +static bool should_thaw_current(bool check_kthr_stop)
>> +{
>> +     if (!freezing(current) ||
>> +         (check_kthr_stop && kthread_should_stop()) ||
>> +         test_thread_flag(TIF_MEMDIE))
>> +             return true;
>> +     else
>> +             return false;
>> +}
>
> I'm not sure this is safe w.r.t. hibernation.  Please cc Rafael on
> freezer related changes.

Or we can just check for cgroup freeze, something like below:

diff --git a/kernel/freezer.c b/kernel/freezer.c
index 33cbcb0..b06a059 100644
--- a/kernel/freezer.c
+++ b/kernel/freezer.c
@@ -56,7 +56,8 @@ static bool should_thaw_current(bool check_kthr_stop)
 {
        if (!freezing(current) ||
            (check_kthr_stop && kthread_should_stop()) ||
-           test_thread_flag(TIF_MEMDIE))
+           /* It might not be safe to check TIF_MEMDIE for pm freeze */
+           (cgroup_freezing(current) && test_thread_flag(TIF_MEMDIE)))
                return true;
        else
                return false;


Are you happy now, Tejun? :)
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