cgconfig daemon restart leaves threads in root cgroup

I'd like to ask if my explanation of the behavior I observe is correct.

The behavior: After restarting cgconfig daemon, the processes have correct core affinity (as verified by taskset) but the threads end up with affinity for ALL cores (0-35 in our case, also as verified by taskset).

The explanation: Shutting down cgconfig daemon unmounts the /cgroup filesystem. That puts all processes into the ROOT cgroup. When cgconfig is restarted, it applies the correct cgroup to processes but not to threads.

The evidence: I executed the following command to find out who is running on the "isolated" core 19:

ps -eL -o "tid,pid,psr"| grep "19$"

Only one non-kernel thread should be running there, but I see a lot of them.

Example:

180978 180957  19

Checking on this tid/pid, I see this for thread:

$ taskset -pc  180978
pid 180978's current affinity list: 0-35

And this for process

$ taskset -pc  180957
pid 180957's current affinity list: 1,3-18,20-28,30,32,33,35

So thread somehow ended up with different affinity from the process.

Furthermore, looking under /cgroup mount yields this for process:

$ find /cgroup/cpuset  -name tasks | xargs grep 180957
/cgroup/cpuset/appXXX/XXXcommon/tasks:180957

And this for thread:

$ find /cgroup/cpuset  -name tasks | xargs grep 180978
/cgroup/cpuset/tasks:180978

So we can see that the thread somehow ended up in root group.

To reiterate: could someone please confirm or deny that the restarting of the cgconfig daemon sets the cgroups for processes correctly, but leaves the threads in the root cgroup.

Environment: Red Hat Enterprise Linux Server release 6.8 (Santiago)