Re: [patch v3] mm, oom: do not schedule if current has been killed

[KOSAKI Motohiro <kosaki.motohiro@gmail.com>]

(6/19/12 4:58 PM), David Rientjes wrote:
> The oom killer currently schedules away from current in an
> uninterruptible sleep if it does not have access to memory reserves.
> It's possible that current was killed because it shares memory with the
> oom killed thread or because it was killed by the user in the interim,
> however.
> 
> This patch only schedules away from current if it does not have a pending
> kill, i.e. if it does not share memory with the oom killed thread.  It's
> possible that it will immediately retry its memory allocation and fail,
> but it will immediately be given access to memory reserves if it calls
> the oom killer again.
> 
> This prevents the delay of memory freeing when threads that share memory
> with the oom killed thread get unnecessarily scheduled.
> 
> Signed-off-by: David Rientjes <rientjes@google.com>
> ---
>  mm/oom_kill.c |   11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/mm/oom_kill.c b/mm/oom_kill.c
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -746,11 +746,11 @@ out:
>  	read_unlock(&tasklist_lock);
>  
>  	/*
> -	 * Give "p" a good chance of killing itself before we
> -	 * retry to allocate memory unless "p" is current
> +	 * Give the killed threads a good chance of exiting before trying to
> +	 * allocate memory again.
>  	 */
> -	if (killed && !test_thread_flag(TIF_MEMDIE))
> -		schedule_timeout_uninterruptible(1);
> +	if (killed)
> +		schedule_timeout_killable(1);
>  }

This is not match I expected. but I have no seen a big problem.

Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>


>  
>  /*
> @@ -765,6 +765,5 @@ void pagefault_out_of_memory(void)
>  		out_of_memory(NULL, 0, 0, NULL, false);
>  		clear_system_oom();
>  	}
> -	if (!test_thread_flag(TIF_MEMDIE))
> -		schedule_timeout_uninterruptible(1);
> +	schedule_timeout_killable(1);
>  }
> 
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