mm/list_lru.c: add memcg argument to list_lru_from_kmem()

This is just refactoring to allow the next patches to have memcg pointer
in list_lru_from_kmem().

Link: http://lkml.kernel.org/r/153063060664.1818.9541345386733498582.stgit@localhost.localdomain
Signed-off-by: Kirill Tkhai <[email protected]>
Acked-by: Vladimir Davydov <[email protected]>
Tested-by: Shakeel Butt <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Guenter Roeck <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Josef Bacik <[email protected]>
Cc: Li RongQing <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Matthias Kaehlcke <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Philippe Ombredanne <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Sahitya Tummala <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Waiman Long <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

mm/list_lru.c

@@ -65,18 +65,24 @@ static __always_inline struct mem_cgroup *mem_cgroup_from_kmem(void *ptr)
 }
 
 static inline struct list_lru_one *
-list_lru_from_kmem(struct list_lru_node *nlru, void *ptr)
+list_lru_from_kmem(struct list_lru_node *nlru, void *ptr,
+		   struct mem_cgroup **memcg_ptr)
 {
-	struct mem_cgroup *memcg;
+	struct list_lru_one *l = &nlru->lru;
+	struct mem_cgroup *memcg = NULL;
 
 	if (!nlru->memcg_lrus)
-		return &nlru->lru;
+		goto out;
 
 	memcg = mem_cgroup_from_kmem(ptr);
 	if (!memcg)
-		return &nlru->lru;
+		goto out;
 
-	return list_lru_from_memcg_idx(nlru, memcg_cache_id(memcg));
+	l = list_lru_from_memcg_idx(nlru, memcg_cache_id(memcg));
+out:
+	if (memcg_ptr)
+		*memcg_ptr = memcg;
+	return l;
 }
 #else
 static void list_lru_register(struct list_lru *lru)
@@ -99,8 +105,11 @@ list_lru_from_memcg_idx(struct list_lru_node *nlru, int idx)
 }
 
 static inline struct list_lru_one *
-list_lru_from_kmem(struct list_lru_node *nlru, void *ptr)
+list_lru_from_kmem(struct list_lru_node *nlru, void *ptr,
+		   struct mem_cgroup **memcg_ptr)
 {
+	if (memcg_ptr)
+		*memcg_ptr = NULL;
 	return &nlru->lru;
 }
 #endif /* CONFIG_MEMCG_KMEM */
@@ -113,7 +122,7 @@ bool list_lru_add(struct list_lru *lru, struct list_head *item)
 
 	spin_lock(&nlru->lock);
 	if (list_empty(item)) {
-		l = list_lru_from_kmem(nlru, item);
+		l = list_lru_from_kmem(nlru, item, NULL);
 		list_add_tail(item, &l->list);
 		l->nr_items++;
 		nlru->nr_items++;
@@ -133,7 +142,7 @@ bool list_lru_del(struct list_lru *lru, struct list_head *item)
 
 	spin_lock(&nlru->lock);
 	if (!list_empty(item)) {
-		l = list_lru_from_kmem(nlru, item);
+		l = list_lru_from_kmem(nlru, item, NULL);
 		list_del_init(item);
 		l->nr_items--;
 		nlru->nr_items--;