linux-kernel - Re: [patch 03/12] mm: oom_kill: switch test-and-clear of known TIF

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Date:	Thu, 26 Mar 2015 12:57:40 +0100
From:	Michal Hocko <mhocko@...e.cz>
To:	Johannes Weiner <hannes@...xchg.org>
Cc:	linux-mm@...ck.org, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	Huang Ying <ying.huang@...el.com>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Dave Chinner <david@...morbit.com>,
	Theodore Ts'o <tytso@....edu>
Subject: Re: [patch 03/12] mm: oom_kill: switch test-and-clear of known
 TIF_MEMDIE to clear

On Wed 25-03-15 02:17:07, Johannes Weiner wrote:
> exit_oom_victim() already knows that TIF_MEMDIE is set, and nobody
> else can clear it concurrently.  Use clear_thread_flag() directly.

Yeah. This is a left over from the review process. I originally did
unmarking unconditionally but Tejun suggested calling test_thread_flag
before calling here. So the test_and_clear is safe here.

> Signed-off-by: Johannes Weiner <hannes@...xchg.org>

Acked-by: Michal Hocko <mhocko@...e.cz>

> ---
>  mm/oom_kill.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> index b2f081fe4b1a..4b9547be9170 100644
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -435,8 +435,7 @@ void mark_oom_victim(struct task_struct *tsk)
>   */
>  void exit_oom_victim(void)
>  {
> -	if (!test_and_clear_thread_flag(TIF_MEMDIE))
> -		return;
> +	clear_thread_flag(TIF_MEMDIE);
>  
>  	down_read(&oom_sem);
>  	/*
> -- 
> 2.3.3
> 

-- 
Michal Hocko
SUSE Labs
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