Those structures are only used for memcgs that are effectively using
kmemcg. However, in a later patch I intend to use scan that list
inconditionally (list empty meaning no kmem caches present), which
simplifies the code a lot.

So move the initialization to early kmem creation.

Signed-off-by: Glauber Costa <redacted>
Cc: Dave Chinner <redacted>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <redacted>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <redacted>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kamezawa Hiroyuki <redacted>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 mm/memcontrol.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e6a7848..1ff72f9 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c

@@ -3249,9 +3249,7 @@ int memcg_update_cache_sizes(struct mem_cgroup *memcg)
 
 	memcg_update_array_size(num + 1);
 
-	INIT_LIST_HEAD(&memcg->memcg_slab_caches);
 	INIT_WORK(&memcg->kmemcg_shrink_work, kmemcg_shrink_work_fn);
-	mutex_init(&memcg->slab_caches_mutex);
 
 	return 0;
 out:

@@ -6121,6 +6119,8 @@ static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
 {
 	int ret;
 
+	INIT_LIST_HEAD(&memcg->memcg_slab_caches);
+	mutex_init(&memcg->slab_caches_mutex);
 	memcg->kmemcg_id = -1;
 	ret = memcg_propagate_kmem(memcg);
 	if (ret)

-- 
1.8.1.4