Xen devel - May 2005 - unregister_netdevice: Waiting for vif7.0 to become free

Hi all,

I was hoping that someone might be able to shed some light on what is 
happening here. I will outline my setup:

I have seven xen domUs, and one (duh!) dom0 all running a linux 
2.6.11.10 locally compiled version of Linux. If needed, I can attach 
the the configurations that I have used. Eth0 and Eth1 have both been 
assigned to dom0, as well as a created tap1 to hold the domU network. 
Each domU has 1 bridged interface onto tap1. Further, each domU has 
three LVM partitions as it''s backing store onto the disk. I think that 
this is all of the relevant details, let me know if you want more :-) 
Oh, these linuxes were all built with the xen-testing source tarball 
from 2005-05-21.

Anyway, whenever I shutdown my 7th domU (the one with id=7) then I get 
the following error:

Message from syslogd@kruimel at Mon May 23 19:20:35 2005 ...
kruimel kernel: unregister_netdevice: waiting for vif7.0 to become free. Usage
count = 1

At this point, my console locks up, although I can still ssh into dom0 
and the remaining domUs. Further, after this point no other xen 
instance can properly shut down. If I shut down any of the other domUs 
first, everything appears to be OK. Also, because none of the other 
domUs can terminate, I can no longer reboot the machine, as xendomains 
will not terminate.

I would ask this on -user, however, this is clearly an error of some 
form, and has led to a DOS for me, as I had tried to remotely reboot 
the machine... due to the lack of shutdown I had to physically hard 
reset the machine. (alt-sysrq sub) also works.

If I can provide any further information please let me know.

Cheers,
Paul

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On Mon, May 23, 2005 at 07:39:48PM +0200, Paul Wagland
wrote:
> Hi all,
> 
> Anyway, whenever I shutdown my 7th domU (the one with id=7) then I get 
> the following error:
> 
> Message from syslogd@kruimel at Mon May 23 19:20:35 2005 ...
> kruimel kernel: unregister_netdevice: waiting for vif7.0 to become free.
Usage count = 1
Just so that everyone knows, and that this answer might be searchable in the
archives...

I have (I think) found a solution. Do not bind xen-br0 to tap1.

I have now just created a "naked" xen-br0, that is, one that is not
attached to any other interface, and it now appears to be OK. Whereas before it
would die whenever I shut down the last domU, now it appears to be running
smoothly.

Thanks to knewt for the help!

Cheers,
Paul

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On 23 May 2005, at 21:48, Paul Wagland wrote:
>> Anyway, whenever I shutdown my 7th domU (the one with id=7) then I get
>> the following error:
>>
>> Message from syslogd@kruimel at Mon May 23 19:20:35 2005 ...
>> kruimel kernel: unregister_netdevice: waiting for vif7.0 to become 
>> free. Usage count = 1
>
> Just so that everyone knows, and that this answer might be searchable 
> in the archives...
>
> I have (I think) found a solution. Do not bind xen-br0 to tap1.
>
> I have now just created a "naked" xen-br0, that is, one that is
not
> attached to any other interface, and it now appears to be OK. Whereas 
> before it would die whenever I shut down the last domU, now it appears 
> to be running smoothly.
>
> Thanks to knewt for the help!
That''s a very weird bug. Did it occur only when you dropped vif7.0, or 
did it occur for whichever vif you happened to drop last?

  -- Keir


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On Mon, May 23, 2005 at 09:58:15PM +0100, Keir Fraser
wrote:
> 
> On 23 May 2005, at 21:48, Paul Wagland wrote:
> 
> >>Anyway, whenever I shutdown my 7th domU (the one with id=7) then I
get
> >>the following error:
> >>
> >>Message from syslogd@kruimel at Mon May 23 19:20:35 2005 ...
> >>kruimel kernel: unregister_netdevice: waiting for vif7.0 to become 
> >>free. Usage count = 1
> >
> >Just so that everyone knows, and that this answer might be searchable 
> >in the archives...
> >
> >I have (I think) found a solution. Do not bind xen-br0 to tap1.
> >
> >I have now just created a "naked" xen-br0, that is, one that
is not
> >attached to any other interface, and it now appears to be OK. Whereas 
> >before it would die whenever I shut down the last domU, now it appears 
> >to be running smoothly.
> >
> >Thanks to knewt for the help!
> 
> That''s a very weird bug. Did it occur only when you dropped
vif7.0, or
> did it occur for whichever vif you happened to drop last?
On the the first point we agree ;-)

It seemed to happen whenever I shut down my last started vif. I.e.
normally it happens on vif7.0, as I have seven xens, however when I was
running with only six xens, then it started happening on vif6.0.

Odd eh?

Cheers,
Paul

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