[libvirt] Potential problem with /proc/mounts items that don't exist inside Kubernetes

[Daniel P. Berrange]

On Thu, Jul 06, 2017 at 11:11:03AM +0200, Juan Hernández wrote:
> Hello all,
> 
> This is my first mail to this list, so let me introduce myself. My name is
> Juan Hernandez, and I work in the oVirt team. Currently I am experimenting
> with the integration between ManageIQ and KubeVirt.
> 
> I recently detected a potential issue when running libvirt inside
> Kubernetes, as part of KubeVirt. There are entries in /proc/mounts that
> don't exist, and libvirt can't start virtual machines because of that. This
> is specific to this enviroment, but I think it may be worth addressing it in
> libvirt itself. See the following issue for details:
> 
>   Libvirt fails when there are hidden cgroup mount points in `/proc/mounts`
>   https://github.com/kubevirt/libvirt/issues/4
> 
> I suggested a possible fix there, which seems simple, but it makes all tests
> fail. I'd be happy to fix the tests as well, but I would need some guidance
> on how to do so. Any suggestion is welcome.

The root cause problem will be the code that parse /proc/mounts. It needs
to pick the last entry in the mounts file, since the earlier ones can be
hidden. For some reason virCgroupDetectMountsFromFile instead picks the
first entry, so that function needs updating todo the reverse.

Regards,
Daniel
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