linux-kernel - [PATCH] mm, memcg: fix mem_cgroup

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Message-Id: <20171128161941.20931-1-shakeelb@google.com>
Date:   Tue, 28 Nov 2017 08:19:41 -0800
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Huang Ying <ying.huang@...el.com>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Michal Hocko <mhocko@...nel.org>,
        Greg Thelen <gthelen@...gle.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        cgroups@...r.kernel.org, Shakeel Butt <shakeelb@...gle.com>,
        stable@...r.kernel.org
Subject: [PATCH] mm, memcg: fix mem_cgroup_swapout() for THPs

The commit d6810d730022 ("memcg, THP, swap: make mem_cgroup_swapout()
support THP") changed mem_cgroup_swapout() to support transparent huge
page (THP). However the patch missed one location which should be
changed for correctly handling THPs. The resulting bug will cause the
memory cgroups whose THPs were swapped out to become zombies on
deletion.

Fixes: d6810d730022 ("memcg, THP, swap: make mem_cgroup_swapout() support THP")
Signed-off-by: Shakeel Butt <shakeelb@...gle.com>
Cc: stable@...r.kernel.org
---
 mm/memcontrol.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 50e6906314f8..ac2ffd5e02b9 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6044,7 +6044,7 @@ void mem_cgroup_swapout(struct page *page, swp_entry_t entry)
 	memcg_check_events(memcg, page);
 
 	if (!mem_cgroup_is_root(memcg))
-		css_put(&memcg->css);
+		css_put_many(&memcg->css, nr_entries);
 }
 
 /**
-- 
2.15.0.417.g466bffb3ac-goog