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From:   Miaohe Lin <linmiaohe@huawei.com>
To:     <hannes@cmpxchg.org>, <mhocko@kernel.org>,
        <vdavydov.dev@gmail.com>, <akpm@linux-foundation.org>
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        <linmiaohe@huawei.com>
Subject: [PATCH 5/5] mm, memcg: always call __mod_node_page_state() with preempt disabled
Date:   Thu, 29 Jul 2021 20:57:55 +0800
Message-ID: <20210729125755.16871-6-linmiaohe@huawei.com>
In-Reply-To: <20210729125755.16871-1-linmiaohe@huawei.com>
References: <20210729125755.16871-1-linmiaohe@huawei.com>
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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@huawei.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