linux-kernel - Re: [PATCH 8/8] mm: Give up allocation if the task have fatal signal

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Date:	Tue, 15 Dec 2009 08:54:55 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	Rik van Riel <riel@...hat.com>, lwoodman@...hat.com,
	akpm@...ux-foundation.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, minchan.kim@...il.com
Subject: Re: [PATCH 8/8] mm: Give up allocation if the task have fatal
 signal

On Mon, 14 Dec 2009 21:32:58 +0900 (JST)
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com> wrote:

> In OOM case, almost processes may be in vmscan. There isn't any reason
> the killed process continue allocation. process exiting free lots pages
> rather than greedy vmscan.
> 
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> ---
>  mm/page_alloc.c |    8 ++++++++
>  1 files changed, 8 insertions(+), 0 deletions(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index ca9cae1..8a9cbaa 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1878,6 +1878,14 @@ rebalance:
>  		goto got_pg;
>  
>  	/*
> +	 * If the allocation is for userland page and we have fatal signal,
> +	 * there isn't any reason to continue allocation. instead, the task
> +	 * should exit soon.
> +	 */
> +	if (fatal_signal_pending(current) && (gfp_mask & __GFP_HIGHMEM))
> +		goto nopage;

If we jump nopage, we meets dump_stack and show_mem. 
Even, we can meet OOM which might kill innocent process.

> +
> +	/*
>  	 * If we failed to make any progress reclaiming, then we are
>  	 * running out of options and have to consider going OOM
>  	 */
> -- 
> 1.6.5.2
> 
> 
> 


-- 
Kind regards,
Minchan Kim
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