[fedora-virt] libvirtd crashes host when autostarting

[Mark McLoughlin]

On Fri, 2009-10-09 at 09:45 -0400, Rich Mahn wrote:
> Summary:
>    My host crashes when I use the autostart function in
> libvirtd.
> 
> This command sequence works fine:
> 
> service libvirtd stop
> virsh autostart mydomain --disable
> service lib virtd start
> virsh start mydomain
> 
> This command sequence will crash the host:
> 
> service libvirtd stop
> virsh autostart mydomain
> service libvirtd start
> 
> 
> I can't find any error messages related to this.  The host system
> freezes, the keyboard starts blinking the caps-lock and scroll-lock,
> and as best I can tell, the kernel has stopped running.

Ouch, that's really bad. This is a 2.6.30 kernel, right? Is it still
reproducible with an older 2.6.29 kernel or a 2.6.31 kernel from
rawhide?

This is ultimately a kernel bug, userspace shouldn't be able to screw up
the kernel like this.

It'd be good to get this into bugzilla:

  https://fedoraproject.org/wiki/Reporting virtualization bugs

> If I starting up the host system with the VM autostarted, I sometimes
> get messages that look like kernel errors on the screen, but I don't
> find them in any log files so far.  They seem to be related to networking.
> 
> Here's some configuration information--I don't know really what all is
> needed, but this, I guess is a start:
> 
> Host and VM both Fedora 11 with the lastest updates.
> Host machine in Intel based with the virtual support turned on.
> 
> In the /var/log/libvirtd/qemu directory, the command line to start
> the virtual machine is different when started from autostart.  The
> difference is in this portion:
> 
> 	    -net tap,fd=11,vlan=0	for failure (autostart) and
> 	    -net tap,fd=18,vlan=0	for success

Interesting, but I can't immediately think where the difference may come
from or how it could be related to the kernel lockup.

Cheers,
Mark.