linux-kernel - [PATCH 5/5] mm, memcg: always call __mod_node_page

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Message-ID: <20210729125755.16871-6-linmiaohe@huawei.com>
Date:   Thu, 29 Jul 2021 20:57:55 +0800
From:   Miaohe Lin <linmiaohe@...wei.com>
To:     <hannes@...xchg.org>, <mhocko@...nel.org>,
        <vdavydov.dev@...il.com>, <akpm@...ux-foundation.org>
CC:     <shakeelb@...gle.com>, <guro@...com>, <willy@...radead.org>,
        <alexs@...nel.org>, <richard.weiyang@...il.com>,
        <songmuchun@...edance.com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, <cgroups@...r.kernel.org>,
        <linmiaohe@...wei.com>
Subject: [PATCH 5/5] mm, memcg: always call __mod_node_page_state() with preempt disabled

We should always ensure __mod_node_page_state() is called with preempt
disabled or percpu ops may manipulate the wrong cpu when preempt happened.

Fixes: b4e0b68fbd9d ("mm: memcontrol: use obj_cgroup APIs to charge kmem pages")
Signed-off-by: Miaohe Lin <linmiaohe@...wei.com>
---
 mm/memcontrol.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 70a32174e7c4..616d1a72ece3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -697,8 +697,8 @@ void __mod_lruvec_page_state(struct page *page, enum node_stat_item idx,
 	memcg = page_memcg(head);
 	/* Untracked pages have no memcg, no lruvec. Update only the node */
 	if (!memcg) {
-		rcu_read_unlock();
 		__mod_node_page_state(pgdat, idx, val);
+		rcu_read_unlock();
 		return;
 	}
 
-- 
2.23.0