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Date: Tue, 12 Jul 2011 10:12:28 -0400
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
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Cc: xen-devel@lists.xensource.com, julie Sullivan <kernelmail.jms@gmail.com>,
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Subject: Re: PROBLEM: 3.0-rc kernels unbootable since -rc3
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> >   [<c042d0f5>] task_waking_fair+0x14  <--
> 
> Hmmm...  This is a 32-bit system, isn't it?

Yes. I ran this little loop:

#!/bin/bash

ID=`xl list | grep Fedora | awk '  { print $2}'`

rm -f cpu*.log
while (true) do
	xl pause $ID
	 /usr/lib64/xen/bin/xenctx -s /mnt/tmp/FC15-32/System.map-3.0.0-rc6-julie-tested-dirty -a $ID 0 >> cpu0.log
	 /usr/lib64/xen/bin/xenctx -s /mnt/tmp/FC15-32/System.map-3.0.0-rc6-julie-tested-dirty -a $ID 1 >> cpu1.log
	 /usr/lib64/xen/bin/xenctx -s /mnt/tmp/FC15-32/System.map-3.0.0-rc6-julie-tested-dirty -a $ID 2 >> cpu2.log
	 /usr/lib64/xen/bin/xenctx -s /mnt/tmp/FC15-32/System.map-3.0.0-rc6-julie-tested-dirty -a $ID 3 >> cpu3.log
	xl unpause $ID
done

To get an idea what the CPU is doing before it hits the task_waking_fair
and there isn't anything daming. Here are the logs:

http://darnok.org/xen/cpu1.log

> 
> Could you please add a check to the loop in task_waking_fair() and
> do a printk() if the loop does (say) more than 1000 passes without
> exiting?

Of course. Let me queue that up.