/* This function returns the number of memcg under hierarchy tree. Returns 1(self count) if no children.  */
static int mem_cgroup_count_children(struct mem_cgroup *mem)
/* This function returns the number of memcg under hierarchy tree. Returns 1(self count) if no children.  */
static int mem_cgroup_count_children(struct mem_cgroup *mem)
{
	int num = 0;
 	mem_cgroup_walk_tree(mem, &num, mem_cgroup_count_children_cb);
	return num;
}