From:   Wei Yang <richard.weiyang@gmail.com>
To:     hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com,
        akpm@linux-foundation.org, shakeelb@google.com, guro@fb.com,
        vbabka@suse.cz, willy@infradead.org, songmuchun@bytedance.com,
        shy828301@gmail.com, surenb@google.com
Cc:     linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
        linux-mm@kvack.org, Wei Yang <richard.weiyang@gmail.com>
Subject: [PATCH 3/4] mm/memcg: retrieve parent memcg from css.parent
Date:   Tue, 11 Jan 2022 01:03:01 +0000
Message-Id: <20220111010302.8864-3-richard.weiyang@gmail.com>
In-Reply-To: <20220111010302.8864-1-richard.weiyang@gmail.com>
References: <20220111010302.8864-1-richard.weiyang@gmail.com>
Precedence: bulk

The parent we get from page_counter is correct, while this is two
different hierarchy.

Let's retrieve the parent memcg from css.parent just like parent_cs(),
blkcg_parent(), etc.

Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
---
 include/linux/memcontrol.h | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 0c5c403f4be6..12bf443f7b14 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -886,9 +886,7 @@ static inline struct mem_cgroup *lruvec_memcg(struct lruvec *lruvec)
  */
 static inline struct mem_cgroup *parent_mem_cgroup(struct mem_cgroup *memcg)
 {
-	if (!memcg->memory.parent)
-		return NULL;
-	return mem_cgroup_from_counter(memcg->memory.parent, memory);
+	return mem_cgroup_from_css(memcg->css.parent);
 }
 
 static inline bool mem_cgroup_is_descendant(struct mem_cgroup *memcg,
-- 
2.33.1