When using the 'ns' cgroup controller, the moment a process calls
'unshare(CLONE_NEWNS)', it will be given a private cgroup tree
under its current location. This really messages up the LXC
controller process, because it ends up creating the containers'
cgroup in the wrong place. The fix is fairly easy, just move
the cgroup setup before the code which calls unshare(). The
'ns' controller will still create extra undesired cgroups, but
they at least won't break libvirt's setup now.
The patch also adds a missing cgroups allow rule for /dev/tty
device node