Re: [Xen-devel] xl vcpu-set crashes Dom0

To:	Andre Przywara <andre.przywara@xxxxxxx>
Subject:	Re: [Xen-devel] xl vcpu-set crashes Dom0
From:	Keir Fraser <keir.xen@xxxxxxxxx>
Date:	Mon, 28 Feb 2011 20:51:12 +0000
Cc:	Juergen Gross <juergen.gross@xxxxxxxxxxxxxx>, xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date:	Mon, 28 Feb 2011 12:52:18 -0800
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Thread-topic:	[Xen-devel] xl vcpu-set crashes Dom0
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On 28/02/2011 17:23, "Andre Przywara" <andre.przywara@xxxxxxx> wrote:

> Hi,
> 
> as mentioned earlier today I had some issues with patch 22934, which
> decreases the number of vCPUs for Dom0 in case of cpupool-numa-split.
> I now found that this is not directly related to this patch, as it
> triggers also with "xl vcpu-set". So far I tried the following combinations:
> c/s 22956 on a machine with 48 physical CPUs:
> not restricted dom0:
> xl vcpu-set 0 6  => crashes
>          xl vcpu-set 0 47 => crashes
> dom0_max_vcpus=6
> xl vcpu-set 0 5  => crashes
>          xm vcpu-set 0 5  => crashes
> 
> The only message I get is:
> root@dosorca:~# xm vcpu-set 0 5
> (XEN) Domain 0 crashed: rebooting machine in 5 seconds.

Dom0 has oopsed. If you have a synchronous log of dmesg (e.g., via serial)
then you should be able to get an oops message and backtrace from dom0
kernel. My first guess would be this is a bug in the kernel's handling of
cpu hotplug requests via xenstore.

 -- Keir

> Debugging turned out that for instance the libxl_set_vcpuonline()
> returns without an error, but the machine then crashes afterwards.
> 
> Can someone reproduce this? Any ideas?
> 
> Regards,
> Andre.



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Re: [Xen-devel] xl vcpu-set crashes Dom0