Comment 7 for bug 1549363

As for the cgroups, we've noticed at least one issue in the cgfs logic of LXC which was fixed earlier today, the package is still going through QA (currently in proposed), should make it to the release pocket within a couple of hours.

The fix was specifically to fix unprivileged but root-owned containers failing to start due to using the wrong cgroup paths. I'm not sure if that covers this bug's specific case. If it doesn't then we'll have to look at this more closely.

Note that those regressions are showing up as a result of us removing cgmanager and switching to straight cgroupfs, things also got slightly more messy as that particular LXC change ended up landing right around the same time as the first cgns enabled kernel which also happened to be broken when used in unprivileged containers.

So what we know right now is:
 - lxc prior to 2.0.0~rc3-0ubuntu2 will fail to setup cgroups for unprivileged containers spawned by the root user, leading to container startup failures
 - linux prior to 4.4.0-8-generic will fail to mount cgroupfs inside unprivileged containers, leading to container starting up but pid1 immediately failing and no other processes getting spawned.