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

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Message-ID: <alpine.DEB.2.02.1408090152240.11855@chino.kir.corp.google.com>
Date:	Sat, 9 Aug 2014 01:55:13 -0700 (PDT)
From:	David Rientjes <rientjes@...gle.com>
To:	Cong Wang <xiyou.wangcong@...il.com>
cc:	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 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?

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

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?
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