memcg: root_cgroup cannot reach mem_cgroup_move_parent

The root cgroup cannot be destroyed so we never hit it down the
mem_cgroup_pre_destroy path and mem_cgroup_force_empty_write shouldn't
even try to do anything if called for the root.

This means that mem_cgroup_move_parent doesn't have to bother with the
root cgroup and it can assume it can always move charges upwards.

Signed-off-by: Michal Hocko <[email protected]>
Reviewed-by: Tejun Heo <[email protected]>
Reviewed-by: Glauber Costa <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>

0 files changed, 0 insertions, 0 deletions