From fa2cb5eeefd87ed46657aed97091e4bc098c4d2b Mon Sep 17 00:00:00 2001
From: Andrew Morton <akpm@linux-foundation.org>
Date: Fri, 9 Nov 2012 14:04:19 +1100
Subject: [PATCH] slub-slub-specific-propagation-changes-fix

tweak code to avoid __maybe_unused

Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 mm/slub.c | 30 +++++++++++++++---------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/mm/slub.c b/mm/slub.c
index 4cca656bfa1b..9cdb6f1adc43 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -5175,7 +5175,6 @@ static ssize_t slab_attr_store(struct kobject *kobj,
 	struct slab_attribute *attribute;
 	struct kmem_cache *s;
 	int err;
-	int i __maybe_unused;
 
 	attribute = to_slab_attr(attr);
 	s = to_slab(kobj);
@@ -5185,23 +5184,24 @@ static ssize_t slab_attr_store(struct kobject *kobj,
 
 	err = attribute->store(s, buf, len);
 #ifdef CONFIG_MEMCG_KMEM
-	if (slab_state < FULL)
-		return err;
+	if (slab_state >= FULL && err >= 0 && is_root_cache(s)) {
+		int i;
 
-	if ((err < 0) || !is_root_cache(s))
-		return err;
+		mutex_lock(&slab_mutex);
+		if (s->max_attr_size < len)
+			s->max_attr_size = len;
 
-	mutex_lock(&slab_mutex);
-	if (s->max_attr_size < len)
-		s->max_attr_size = len;
-
-	for_each_memcg_cache_index(i) {
-		struct kmem_cache *c = cache_from_memcg(s, i);
-		if (c)
-			/* return value determined by the parent cache only */
-			attribute->store(c, buf, len);
+		for_each_memcg_cache_index(i) {
+			struct kmem_cache *c = cache_from_memcg(s, i);
+			/*
+			 * This function's return value is determined by the
+			 * parent cache only
+			 */
+			if (c)
+				attribute->store(c, buf, len);
+		}
+		mutex_unlock(&slab_mutex);
 	}
-	mutex_unlock(&slab_mutex);
 #endif
 	return err;
 }
-- 
2.39.5