mm: introduce CONFIG_MEMCG_KMEM as combination of CONFIG_MEMCG && !CONFIG_SLOB

Introduce new config option, which is used to replace repeating
CONFIG_MEMCG && !CONFIG_SLOB pattern.  Next patches add a little more
memcg+kmem related code, so let's keep the defines more clearly.

Link: http://lkml.kernel.org/r/153063053670.1818.15013136946600481138.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Tested-by: Shakeel Butt <shakeelb@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Josef Bacik <jbacik@fb.com>
Cc: Li RongQing <lirongqing@baidu.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matthias Kaehlcke <mka@chromium.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Sahitya Tummala <stummala@codeaurora.org>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/list_lru.c

@@ -12,7 +12,7 @@
 #include <linux/mutex.h>
 #include <linux/memcontrol.h>
 
-#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
+#ifdef CONFIG_MEMCG_KMEM
 static LIST_HEAD(list_lrus);
 static DEFINE_MUTEX(list_lrus_mutex);
 
@@ -103,7 +103,7 @@ list_lru_from_kmem(struct list_lru_node *nlru, void *ptr)
 {
 	return &nlru->lru;
 }
-#endif /* CONFIG_MEMCG && !CONFIG_SLOB */
+#endif /* CONFIG_MEMCG_KMEM */
 
 bool list_lru_add(struct list_lru *lru, struct list_head *item)
 {
@@ -284,7 +284,7 @@ static void init_one_lru(struct list_lru_one *l)
 	l->nr_items = 0;
 }
 
-#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
+#ifdef CONFIG_MEMCG_KMEM
 static void __memcg_destroy_list_lru_node(struct list_lru_memcg *memcg_lrus,
 					  int begin, int end)
 {
@@ -543,7 +543,7 @@ static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
 static void memcg_destroy_list_lru(struct list_lru *lru)
 {
 }
-#endif /* CONFIG_MEMCG && !CONFIG_SLOB */
+#endif /* CONFIG_MEMCG_KMEM */
 
 int __list_lru_init(struct list_lru *lru, bool memcg_aware,
 		    struct lock_class_key *key)