Re: [RFC][PATCH] oom_kill: avoid depends on total_vm and use real RSS/swap value for oom_score (Re: Memory overcommit

[Minchan Kim <minchan.kim@gmail.com>]

On Tue, 27 Oct 2009 16:56:28 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> On Tue, 27 Oct 2009 16:45:26 +0900
> KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.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()...
> 

I think it's good as-is. 
Kernel is hard to know it by effiecient method.
It depends on applications. so Doesnt's task-launcher 
like gnome-session have to control his oom_score? 

Welcome to any ideas if kernel can do it well.

> Thanks,
> -Kame
> 


-- 
Kind regards,
Minchan Kim

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