Automatic merge from submit-queue
Add checks in Create and Update Cgroup methods
This PR is connected to upstream issue for adding pod level cgroups in Kubernetes: #27204
Libcontainer currently doesen't support updates to parent devices cgroups. Until we get libcontainer to support skipping devices cgroup we will have that logic on the kubelet side.
This PR includes:
1. Skip the devices cgroup when updating a cgroup. We only update the memory and cpu subsytems.
2. We explicitly pass all the cgroup paths that don't already exist to Apply()
3. Adds an AlreadyExists() method which is a utility function to check if all the subsystems of a cgroup already exist.
On cgroupManager.Update() we only call Set() and cgroupManager.Create() we only call Apply() method
@vishh PTAL
0f20ab63af