[Pkg-libvirt-maintainers] Bug#983871: Bug#983871: error: internal error: failed to get cgroup backend for 'pathOfController'

[Jonas Schäfer]

Hi again,

I did another test by pinning the bookworm packages (7.6.0-1) and testing 
those. They exhibit the same behaviour as the patched libvirt, that is: in 
some cases, virsh destroy will show an error, but the container will be 
removed cleanly nonetheless.

This is an improvement over the previous situation, where it was impossible to 
destroy a domain.

I'd thus suggest to move ahead with the patch, even if imperfect, as it then 
brings stable to the same state as testing in that regard (and I'll try to 
prepare a bug report for testing).

kind regards,
Jonas

On Wed, 17 Nov 2021 16:10:57 +0100 Jonas Schäfer <jonas at wielicki.name> wrote:
> Hi Guido,
> 
> Thanks for your reply!
> 
> On Wed, 17 Nov 2021 13:11:05 +0100 Guido Günther <gg at godiug.net> wrote:
> > here's the missing link:
> > 
> > https://salsa.debian.org/libvirt-team/libvirt/-/merge_requests/116
> 
> I took the artifacts from there and did another test run. At first glance, 
> everything looked good, but then it failed on destruction of the domain 
again, 
> with:
> 
> error: Unable to read from '/sys/fs/cgroup/machine.slice/machine-
> lxc\x2d4078\x2drouter.scope/system.slice/cgroup.controllers': No such file or 
> directory
> 
> The domain is afterward still fully cleaned up (the cgroup subtree under 
> machine.slice is gone completely), but the error message is still annoying. 
To 
> me it seems like the recursion in the libvirt code is racing against the 
> domain cleaning up after itself somehow, because I get different error 
messages 
> and sometimes it also succeeds:
> 
> root at down ~ › virsh -c lxc:/// destroy router
> Domain 'router' destroyed
> 
> root at down ~ › virsh -c lxc:/// start router
> Domain 'router' started
> 
> root at down ~ › virsh -c lxc:/// destroy router
> error: Failed to destroy domain 'router'
> error: Unable to read from '/sys/fs/cgroup/machine.slice/machine-
> lxc\x2d4078\x2drouter.scope/system.slice/cgroup.controllers': No such file or 
> directory
> 
> root at down ~ › virsh -c lxc:/// start router
> Domain 'router' started
> 
> root at down ~ › virsh -c lxc:/// destroy router
> error: Failed to destroy domain 'router'
> error: Unable to read from '/sys/fs/cgroup/machine.slice/machine-
> lxc\x2d1505\x2drouter.scope/system.slice/system-openvpn.slice/
> cgroup.controllers': No such file or directory
> 
> root at down ~ › dpkg -l | grep libvirt         
> ii  libvirt-clients                         7.0.0-4~1.gbp7decb2             
> amd64        Programs for the libvirt library
> ii  libvirt-daemon                          7.0.0-4~1.gbp7decb2             
> amd64        Virtualization daemon
> ii  libvirt-daemon-config-network           7.0.0-4~1.gbp7decb2             
all          
> Libvirt daemon configuration files (default network)
> ii  libvirt-daemon-config-nwfilter          7.0.0-4~1.gbp7decb2             
all          
> Libvirt daemon configuration files (default network filters)
> ii  libvirt-daemon-driver-lxc               7.0.0-4~1.gbp7decb2             
> amd64        Virtualization daemon LXC connection driver
> ii  libvirt-daemon-driver-qemu              7.0.0-4~1.gbp7decb2             
> amd64        Virtualization daemon QEMU connection driver
> ii  libvirt-daemon-system                   7.0.0-4~1.gbp7decb2             
> amd64        Libvirt daemon configuration files
> ii  libvirt-daemon-system-systemd           7.0.0-4~1.gbp7decb2