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

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Message-ID: <1288836733.2124.18.camel@myhost>
Date:	Thu, 04 Nov 2010 10:12:13 +0800
From:	"Figo.zhang" <zhangtianfei@...dcoretech.com>
To:	David Rientjes <rientjes@...gle.com>
Cc:	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: Re:[PATCH v2]oom-kill: CAP_SYS_RESOURCE should get bonus

On Wed, 2010-11-03 at 18:50 -0700, David Rientjes wrote:
> On Thu, 4 Nov 2010, Figo.zhang wrote:
> 
> > > > CAP_SYS_RESOURCE also had better get 3% bonus for protection.
> > > >
> > > 
> > > 
> > > Would you like to elaborate as to why?
> > > 
> > > 
> > 
> > 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.  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.

In your new heuristic, you also get CAP_SYS_RESOURCE to protection.
see fs/proc/base.c, line 1167:
	if (oom_score_adj < task->signal->oom_score_adj &&
			!capable(CAP_SYS_RESOURCE)) {
		err = -EACCES;
		goto err_sighand;
	}

so i want to protect some process like normal process not
CAP_SYS_RESOUCE, i set a small oom_score_adj , if new oom_score_adj is
small than now and it is not limited resource, it will not adjust, that
seems not right?





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