Comment 11 for bug 1845562

Hello Simon,

The fix for the current release can be made, but, in order for that to happen, we need an exact way how to make the error to happen, and what was your use case. Reading Debian bug and this bug, it appears that you've enabled cgroupv2, correct ?

You likely enabled:

systemd.unified_cgroup_hierarchy
           When specified without an argument or with a true argument, enables the usage of
           unified cgroup hierarchy[8] (a.k.a. cgroups-v2). When specified with a false argument,
           fall back to hybrid or full legacy cgroup hierarchy.

in cmd line, right ? And your error happened because a cpu controller cannot be added to cgroupsv2 if there is a realtime process.

Could you explain what is the realtime process, if you are aware of, and why you need cgroups v2 enabled ? With that, perhaps we can backport a specific fix for libvirt 5.0.0-1ubuntu2.5 (or later) and fix this behavior.

Have you also tried removing rtkit package as a workaround ? Did it work ?