linux-kernel - Re: [RFC][PATCH] oom_kill: avoid depends on total_vm and use real RSS/swap value for oom

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Message-Id: <20091027165628.acda4540.kamezawa.hiroyu@jp.fujitsu.com>
Date:	Tue, 27 Oct 2009 16:56:28 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	Minchan Kim <minchan.kim@...il.com>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	vedran.furac@...il.com, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	"hugh.dickins@...cali.co.uk" <hugh.dickins@...cali.co.uk>,
	"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
	rientjes@...gle.com
Subject: Re: [RFC][PATCH] oom_kill: avoid depends on total_vm and use real
 RSS/swap value for oom_score (Re: Memory overcommit

On Tue, 27 Oct 2009 16:45:26 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> wrote:
  	/*
>  	 * After this unlock we can no longer dereference local variable `mm'
> @@ -92,8 +93,13 @@ unsigned long badness(struct task_struct
>  	 */
>  	list_for_each_entry(child, &p->children, sibling) {
>  		task_lock(child);
> -		if (child->mm != mm && child->mm)
> -			points += child->mm->total_vm/2 + 1;
> +		if (child->mm != mm && child->mm) {
> +			unsigned long cpoint;
> +			/* At considering child, we don't count swap */
> +			cpoint = get_mm_counter(child->mm, anon_rss) +
> +				 get_mm_counter(child->mm, file_rss);
> +			points += cpoint/2 + 1;
> +		}
>  		task_unlock(child);

BTW, I'd like to get rid of this code.

Can't we use other techniques for detecting fork-bomb ?

This check can't catch following type, anyway.

   fork()
     -> fork()
          -> fork()
               -> fork()
                    ....

but I have no good idea.
What is the difference with task-launcher and fork bomb()...

Thanks,
-Kame

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