linux-kernel - Re: running of out memory => kernel crash

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Date:	Wed, 10 Aug 2011 01:14:58 -0700 (PDT)
From:	Mahmood Naderan <nt_mahmood@...oo.com>
To:	David Rientjes <rientjes@...gle.com>
Cc:	Randy Dunlap <rdunlap@...otime.net>,
	"\"linux-kernel@...r.kernel.org\"" <linux-kernel@...r.kernel.org>,
	"linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: running of out memory => kernel crash

>If you're using cpusets or mempolicies, you must ensure that all tasks 
>attached to either of them are not set to OOM_DISABLE.  It seems unlikely 
>that you're using those, so it seems like a system-wide oom condition.

I didn't do that manually. What is the default behaviour? Does oom
working or not?

>If you're using cpusets or mempolicies, you must ensure that all tasks 
>attached to either of them are not set to OOM_DISABLE.  It seems unlikely 
>that you're using those, so it seems like a system-wide oom condition.

For a user process:

root@srv:~# cat /proc/18564/oom_score
9198
root@srv:~# cat /proc/18564/oom_adj
0

And for "init" process:

root@srv:~# cat /proc/1/oom_score
17509
root@srv:~# cat /proc/1/oom_adj
0

Based on my understandings, in an out of memory condition (oom),
the init process is more eligible to be killed!!!!!!! Is that right?

Again I didn't get my answer yet:
What is the default behavior of linux in an oom condition? If the default is,
crash (kernel panic), then how can I change that in such a way to kill
the hungry process?

Thanks a lot.

// Naderan *Mahmood;

----- Original Message -----
From: David Rientjes <rientjes@...gle.com>
To: Mahmood Naderan <nt_mahmood@...oo.com>
Cc: Randy Dunlap <rdunlap@...otime.net>; "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>; linux-mm@...ck.org
Sent: Tuesday, August 9, 2011 8:33 PM
Subject: Re: running of out memory => kernel crash

On Tue, 9 Aug 2011, Mahmood Naderan wrote:

> >Do you have any kernel log panic/oops/Bug messages?
>  
> Actually, that happened for one my diskless nodes 10 days ago.
> What I saw on the screen (not the logs), was 
> "running out of memory.... kernel panic....."
> 

The only similar message in the kernel is "Out of memory and no killable 
processes..." and that panics the machine when there are no eligible 
tasks to kill.

If you're using cpusets or mempolicies, you must ensure that all tasks 
attached to either of them are not set to OOM_DISABLE.  It seems unlikely 
that you're using those, so it seems like a system-wide oom condition.  Do 
cat /proc/*/oom_score and make sure at least some threads have a non-zero 
badness score.  Otherwise, you'll need to adjust their 
/proc/pid/oom_score_adj settings to not be -1000.

Randy also added linux-mm@...ck.org to the cc, but you removed it; please 
don't do that.
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