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Date: Thu, 24 Oct 2002 14:17:43 -0700
From: chrisl@vmware.com
To: Andrea Arcangeli <andrea@suse.de>
Cc: Andrew Morton <akpm@digeo.com>, linux-kernel@vger.kernel.org,
       chrisl@gnuchina.org, Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: writepage return value check in vmscan.c
Message-ID: <20021024211743.GE1398@vmware.com>
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On Thu, Oct 24, 2002 at 10:41:08PM +0200, Andrea Arcangeli wrote:
> On Thu, Oct 24, 2002 at 12:15:32PM -0700, chrisl@vmware.com wrote:
> > Yes, but even now days it will able to lockup machine by doing that.
> > 
> > Try the test bigmm program I attach to this mail. It will simulate vmware's
> > memory mapping. It can easily lockup the machine even though there is
> > enough disk space.
> > 
> > See the comment at the source for parameter. basically, if you want
> > 3 virtual machine, each have 2 process, using 1 G ram each you can do:
> > 
> > bigmm -i 3 -t 2 -c 1024
> > 
> > I run it on two 4G and 8G smp machine. Both can dead lock if I mmap
> > enough memory.
> 
> I run the above command on my laptop with 256M of ram and 1G of swap
> with kde running (though idle) and the task was correctly killed:

That is probably too small ram to start with. What can you expect
to ask for 3G on a 1/4 G machine?

> 
> Oct 24 22:29:32 x30 kernel: VM: killing process bigmm
> 
> the machine never deadlocked. Probably it's one of the oom deadlocks
> that I fixed in my 2.4 -aa tree and that the oom killer heuristic in
> mainline cannot figure out. Please try to reproduce with 2.4.20pre11aa1.
> thanks.

I will definitely try it when I can use that big memory machine again.
Other people is running (windows) test on it right now.

> 
> > Prepare to reset the machine if you try that, you have been warned :-)
> 
> If you're running an oom deadlock prone kernel.

When it dies, it is not deadlock though. Hard disk keep spinning.
It looks like dead loop in swapping and not response to any thing else.
But one thing for sure, OOM did not kill it correctly.

Chris


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