[libvirt] libvirt failed to spawn with namespace

[Michal Privoznik]

On 01/05/2017 08:48 AM, Qiao, Liyong wrote:
> Hi Michal
> 
> Build with the latest libvirt source code, I found failed to spawn a qemu process, not sure if something wrong with my environment, can you please help to take a look at it?
> 
> After build the latest (3.0.0) libvirt, found failed to start an existed domain.
> 
> root at s2600wt:/home/taget/qemu# virsh start kvm02
> error: Failed to start domain kvm02
> error: internal error: Process exited prior to exec: libvirt: QEMU Driver error : Unable to move /dev/mqueue mount: Invalid argument

D'oh. There's a list of FSs that libvirt tries to preserve and bind
mount from the parent namespace. But it is not fault tolerant.

> 
> then I found you had some code get merged, and required to use /dev/mqueue

Yes. Exactly.

> 
> so mount it then start the domain again:
> 
> mount -t mqueue none /dev/mqueue
> 
> root at s2600wt:/home/taget/qemu# virsh start kvm02
> error: Failed to start domain kvm02
> error: An error occurred, but the cause is unknown

Can you get /var/log/libvirt/qemu/kvm02.log?

As a workaround you can set namespaces=[] in qemu.conf, but that is
really meant just like a workaround until all of these edge cases are fixed.

Meanwhile, I started working on a fix that will drop the persistent list
and parse /proc/mounts instead.

Michal