this was the case also without this patch. In order to fix this we need a guarantee that try_get_mem_cgroup_from_page falls back to the current mm's cgroup so it needs css_tryget to fail. This will be fixed up in a later patch because it needs a help from cgroup core (pre_destroy has to be called after css is cleared). Although mem_cgroup_pre_destroy can still fail (if a new task or a new sub-group appears) there is no reason to retry pre_destroy callback from the cgroup core. This means that __DEPRECATED_clear_css_refs has lost its meaning and it can be removed. Changes since v2 - remove __DEPRECATED_clear_css_refs Changes since v1 - use kerndoc - be more specific about mem_cgroup_move_parent possible failures Signed-off-by: Michal Hocko Reviewed-by: Tejun Heo Reviewed-by: Glauber Costa Signed-off-by: Tejun Heo Z"ô«”/x