[LTP] [RFC PATCH] tst_cgroup: Avoid mixing mounts V1 and V2 simultaneously

[Cyril Hrubis]

Hi!
> That's the original design. We tried to keep flexible but ignored
> one exception V1 mounts all controllers and V2 only basic mount.
> (No controllers conflict in this mounting).
> 
> From my observation, if a system(e.g. RHEL8) only announces
> Cgroup V1 support but does not guarantee V2 to be used.
> A test required 'CTRL_BASE' could mount V2 success but
> that V2 is only part work and test will get TBROK.
> We are unable to say this situation is a bug.

So the V2 does not actually work unless there is at least one controller
enabled? That sounds like a bug to me, my system actually uses v1
controllers and unified hierarchy at the same time. The unified
hierarchy is used to group deamon processes and kill them with the
cgropu.kill if needed.

What exactly happens on your system?

-- 
Cyril Hrubis
chrubis@suse.cz