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

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Message-ID: <alpine.DEB.2.00.1108110010220.23622@chino.kir.corp.google.com>
Date:	Thu, 11 Aug 2011 00:13:10 -0700 (PDT)
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\"" <linux-mm@...ck.org>
Subject: Re: running of out memory => kernel crash

On Thu, 11 Aug 2011, Mahmood Naderan wrote:

> >The default behavior is to kill all eligible and unkillable threads until 
> >there are none left to sacrifice (i.e. all kthreads and OOM_DISABLE).
>  
> In a simple test with virtualbox, I reduced the amount of ram to 300MB. 
> Then I ran "swapoff -a" and opened some applications. I noticed that the free
> spaces is kept around 2-3MB and "kswapd" is running. Also I saw that disk
> activity was very high. 
> That mean although "swap" partition is turned off, "kswapd" was trying to do
> something. I wonder how that behavior can be explained?
> 

Despite it's name, kswapd is still active, it's trying to reclaim memory 
to prevent having to kill a process as the last resort.

If /proc/sys/vm/panic_on_oom is not set, as previously mentioned, then 
we'll need the kernel log to diagnose this further.