[PATCH next-akpm] mm/memcg: add missed warning in mem_cgroup_lruvec

From: Alex Shi <alex.shi@linux.alibaba.com>
To: unlisted-recipients:; (no To-header on input)
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Johannes Weiner <hannes@cmpxchg.org>,
	Shakeel Butt <shakeelb@google.com>, Roman Gushchin <guro@fb.com>,
	Michal Hocko <mhocko@suse.com>,
	Yafang Shao <laoar.shao@gmail.com>,
	Alexander Duyck <alexander.h.duyck@linux.intel.com>,
	Hui Su <sh_def@163.com>, Wei Yang <richard.weiyang@gmail.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH next-akpm] mm/memcg: add missed warning in mem_cgroup_lruvec
Date: Fri, 20 Nov 2020 17:30:03 +0800	[thread overview]
Message-ID: <1605864603-49118-1-git-send-email-alex.shi@linux.alibaba.com> (raw)

commit "(mm/memcontrol:rewrite mem_cgroup_page_lruvec())" on mm tree use
mem_cgroup_lruvec to rewrite mem_cgroup_page_lruvec, but it missed a
DEBUG_VM warning as following, since we always charge a page before
return from allocation. Add back this warning is helpful:

	VM_WARN_ON_ONCE_PAGE(!memcg, page);

Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Andrew Morton <akpm@linux-foundation.org> 
Cc: Johannes Weiner <hannes@cmpxchg.org> 
Cc: Shakeel Butt <shakeelb@google.com> 
Cc: Roman Gushchin <guro@fb.com> 
Cc: Michal Hocko <mhocko@suse.com> 
Cc: Yafang Shao <laoar.shao@gmail.com> 
Cc: Alexander Duyck <alexander.h.duyck@linux.intel.com> 
Cc: Hui Su <sh_def@163.com>
Cc: Wei Yang <richard.weiyang@gmail.com> 
Cc: linux-kernel@vger.kernel.org 
---
 include/linux/memcontrol.h | 1 +
 1 file changed, 1 insertion(+)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 925b09ace986..7809020ef7bd 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -618,6 +618,7 @@ static inline struct lruvec *mem_cgroup_lruvec(struct mem_cgroup *memcg,
 		goto out;
 	}
 
+	VM_WARN_ON_ONCE_PAGE(!memcg, page);
 	if (!memcg)
 		memcg = root_mem_cgroup;
 
-- 
2.29.GIT

