mm: Replace cgroup_page bit spinlock

Bit spinlocks are not working on RT. Replace them.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

include/linux/page_cgroup.h

@@ -12,6 +12,7 @@
  */
 struct page_cgroup {
 	unsigned long flags;
+	spinlock_t lock;
 	struct mem_cgroup *mem_cgroup;
 	struct page *page;
 	struct list_head lru;		/* per cgroup LRU list */
@@ -70,17 +71,17 @@ static inline enum zone_type page_cgroup_zid(struct page_cgroup *pc)
 
 static inline void lock_page_cgroup(struct page_cgroup *pc)
 {
-	bit_spin_lock(PCG_LOCK, &pc->flags);
+	spin_lock(&pc->lock);
 }
 
 static inline int trylock_page_cgroup(struct page_cgroup *pc)
 {
-	return bit_spin_trylock(PCG_LOCK, &pc->flags);
+	return spin_trylock(&pc->lock);
 }
 
 static inline void unlock_page_cgroup(struct page_cgroup *pc)
 {
-	bit_spin_unlock(PCG_LOCK, &pc->flags);
+	spin_unlock(&pc->lock);
 }
 
 #else /* CONFIG_CGROUP_MEM_RES_CTLR */

mm/page_cgroup.c

@@ -14,6 +14,7 @@ static void __meminit
 __init_page_cgroup(struct page_cgroup *pc, unsigned long pfn)
 {
 	pc->flags = 0;
+	spin_lock_init(&pc->lock);
 	pc->mem_cgroup = NULL;
 	pc->page = pfn_to_page(pfn);
 	INIT_LIST_HEAD(&pc->lru);