memcg: convert to use cgroup_is_descendant()

This is a preparation to kill css_id.

Signed-off-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d5ff3ce13029b2c99b4ed402898ae0c76a143fde..aa8363ef381cc799a3c7679c7b507d8813f20a44 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1318,7 +1318,7 @@ bool __mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,
                return true;
        if (!root_memcg->use_hierarchy || !memcg)
                return false;
-       return css_is_ancestor(&memcg->css, &root_memcg->css);
+       return cgroup_is_descendant(memcg->css.cgroup, root_memcg->css.cgroup);
 }
 
 static bool mem_cgroup_same_or_subtree(const struct mem_cgroup *root_memcg,