linux-kernel - Re: [Patch] freezer: check OOM kill signal while being frozen

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Date:	Mon, 11 Aug 2014 17:20:50 -0700
From:	Cong Wang <xiyou.wangcong@...il.com>
To:	David Rientjes <rientjes@...gle.com>
Cc:	LKML <linux-kernel@...r.kernel.org>, Michal Hocko <mhocko@...e.cz>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>, Tejun Heo <tj@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [Patch] freezer: check OOM kill signal while being frozen

On Sat, Aug 9, 2014 at 1:55 AM, David Rientjes <rientjes@...gle.com> wrote:
> On Fri, 8 Aug 2014, Cong Wang wrote:
>
>> diff --git a/kernel/freezer.c b/kernel/freezer.c
>> index aa6a8aa..c6d189d 100644
>> --- a/kernel/freezer.c
>> +++ b/kernel/freezer.c
>> @@ -68,7 +68,9 @@ bool __refrigerator(bool check_kthr_stop)
>>               spin_lock_irq(&freezer_lock);
>>               current->flags |= PF_FROZEN;
>>               if (!freezing(current) ||
>> -                 (check_kthr_stop && kthread_should_stop()))
>> +                 (check_kthr_stop && kthread_should_stop()) ||
>> +                 (test_tsk_thread_flag(current, TIF_MEMDIE) &&
>> +                      fatal_signal_pending(current)))
>>                       current->flags &= ~PF_FROZEN;
>>               spin_unlock_irq(&freezer_lock);
>>
>
> All threads with TIF_MEMDIE set would have been killed, why is the check
> for fatal_signal_pending(current) needed?

So just checking TIF_MEMDIE is enough, right?

>
> You can also use test_thread_flag(TIF_MEMDIE) instead since you're only
> concerned with current.
>

OK, will do.

> Furthermore, that conditional is getting difficult to read.  Maybe it
> would help to have a helper function that returns bool that determines
> whether PF_FROZEN should be cleared?

Makes sense.

Thanks.
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