linux-kernel - Re: [PATCH v2]oom-kill: CAP_SYS

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Message-ID: <20101109122437.2e0d71fd@lxorguk.ukuu.org.uk>
Date:	Tue, 9 Nov 2010 12:24:37 +0000
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	"Figo.zhang" <zhangtianfei@...dcoretech.com>
Cc:	David Rientjes <rientjes@...gle.com>,
	figo zhang <figo1802@...il.com>,
	lkml <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>,
	Andrew Morton <akpm@...l.org>
Subject: Re: [PATCH v2]oom-kill: CAP_SYS_RESOURCE should get bonus

> > > process with CAP_SYS_RESOURCE capibility which have system resource
> > > limits, like journaling resource on ext3/4 filesystem, RTC clock. so it
> > > also the same treatment as process with CAP_SYS_ADMIN.
> > > 
> > 
> > NACK, there's no justification that these tasks should be given a 3% 
> > memory bonus in the oom killer heuristic; in fact, since they can allocate 
> > without limits it is more important to target these tasks if they are 
> > using an egregious amount of memory.
> 
> David, Stupid are YOU. you removed CAP_SYS_RESOURCE condition with ZERO
> explanation and Figo reported a regression. That's enough the reason to
> undo. YOU have a guilty to explain why do you want to change and why
> do you think it has justification.
> 
> Don't blame bug reporter. That's completely wrong.

Can people stop throwing things at each other and worry about the facts

- If it's a regression it should get reverted or fixed. But is it
  actually a regression ? Has the underlying behaviour changed in a
  problematic way?

"CAP_SYS_RESOURCE threads have the ability to lower their own oom_score_adj
 values, thus, they should protect themselves if necessary like
 everything else."

The reverse can be argued equally - that they can unprotect themselves if
necessary. In fact it seems to be a "point of view" sort of question
which way you deal with CAP_SYS_RESOURCE, and that to me argues that
changing from old expected behaviour to a new behaviour is a regression.



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