Just to give a small update.

It seems that when installing the willy-lts-kernel backport package on 14.04, 
the VMs stopped getting stuck.

We have now been running 6 weeks without a single VM crashing.

Before, we had 1-2 per day.

Maybe it will be useful to somebody.

Kind regards,


> On 30 Mar 2016, at 14:23, Christophe TREFOIS <christophe.tref...@uni.lu> 
> wrote:
> Hi Kevin,
> Ok thanks for the feedback.
> Do you have experience with kernel panics and more specifically how to get 
> any meaningful message if this is happening?
> According to syslog on the guest, at least after reboot, there's no 
> information that something went wrong.
> Since this seems to leave the qemu world, I'm now not sure where to ask for 
> support in this :(
> Kind regards,
> --
> Christophe 
> Sent from my iPhone
>> On 30 Mar 2016, at 14:14, Kevin Wolf <kw...@redhat.com> wrote:
>> Hi Christophe,
>> Am 30.03.2016 um 13:45 hat Christophe TREFOIS geschrieben:
>>> Another host went down, so I have to prepare info for this one.
>>> I could not SSH to it anymore.
>>> Console would show login screen, but no keystrokes were registered.
>>> I could “suspend” the VM and “run” it, but still can’t SSH to it.
>>> Before suspension, all QEMU threads were around 0%, after resuming, 3 of 
>>> them hover at 100%.
>>> Attached you could find the gdb, core dump, and other logs.
>>> Logs: https://dl.dropboxusercontent.com/u/63261/ubuntu2-logs.tar.gz
>>> Core Dump: https://dl.dropboxusercontent.com/u/63261/core-ubuntu2.tar.gz
>>> Is there anything else we could provide?
>> This sounds much like it's not qemu that hangs (because then stopping
>> and resuming wouldn't work any more), but just the guest OS that is
>> running inside the VM.
>> We've had cases before where qemu was reported to hang with 100% CPU
>> usage and in the end it turned out that the guest kernel had panicked.
>> Can you check whether a guest kernel crash could be the cause? If this
>> is reproducible, maybe the easiest way would be to attach a serial
>> console to the VM and let the kernel print its messages there.
>> Kevin

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