linux-kernel - Re: Memory overcommit

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Date:	Fri, 30 Oct 2009 14:59:33 +0100
From:	Vedran Furač <vedran.furac@...il.com>
To:	David Rientjes <rientjes@...gle.com>
CC:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Hugh Dickins <hugh.dickins@...cali.co.uk>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	minchan.kim@...il.com, Andrew Morton <akpm@...ux-foundation.org>,
	Andrea Arcangeli <aarcange@...hat.com>
Subject: Re: Memory overcommit

David Rientjes wrote:

> On Thu, 29 Oct 2009, Vedran Furac wrote:
> 
>> But then you should rename OOM killer to TRIPK:
>> Totally Random Innocent Process Killer
>>
> 
> The randomness here is the order of the child list when the oom killer 
> selects a task, based on the badness score, and then tries to kill a child 
> with a different mm before the parent.
> 
> The problem you identified in http://pastebin.com/f3f9674a0, however, is a 
> forkbomb issue where the badness score should never have been so high for 
> kdeinit4 compared to "test".  That's directly proportional to adding the 
> scores of all disjoint child total_vm values into the badness score for 
> the parent and then killing the children instead.

Could you explain me why ntpd invoked oom killer? Its parent is init. Or
syslog-ng?

> That's the problem, not using total_vm as a baseline.  Replacing that with 
> rss is not going to solve the issue and reducing the user's ability to 
> specify a rough oom priority from userspace is simply not an option.

OK then, if you have a solution, I would be glad to test your patch. I
won't care much if you don't change total_vm as a baseline. Just make
random killing history.

Regards,

Vedran

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