From c812fed92b2a9f70083a73072a4d022d17c6e3b3 Mon Sep 17 00:00:00 2001
From: Shakeel Butt <shakeelb@google.com>
Date: Wed, 29 Nov 2017 16:11:15 -0800
Subject: [PATCH] mm, memcg: fix mem_cgroup_swapout() for THPs

Commit 5fb61ad53b8f ("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.

Link: http://lkml.kernel.org/r/20171128161941.20931-1-shakeelb@google.com
Fixes: 5fb61ad53b8f ("memcg, THP, swap: make mem_cgroup_swapout() support THP")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: <stable@vger.kernel.org>

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
 mm/memcontrol.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 50e6906314f8d..ac2ffd5e02b91 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);
 }
 
 /**
-- 
2.39.5