From: Thomas Gleixner <tglx@linutronix.de>
Date: Wed, 19 Aug 2009 09:56:42 +0200
Subject: 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 |   15 +++++++++++++++
 mm/page_cgroup.c            |   11 +++++++++++
 2 files changed, 26 insertions(+)

--- a/include/linux/page_cgroup.h
+++ b/include/linux/page_cgroup.h
@@ -24,6 +24,9 @@ enum {
  */
 struct page_cgroup {
 	unsigned long flags;
+#ifdef CONFIG_PREEMPT_RT_BASE
+	spinlock_t pcg_lock;
+#endif
 	struct mem_cgroup *mem_cgroup;
 };
 
@@ -74,12 +77,20 @@ static inline void lock_page_cgroup(stru
 	 * Don't take this lock in IRQ context.
 	 * This lock is for pc->mem_cgroup, USED, MIGRATION
 	 */
+#ifndef CONFIG_PREEMPT_RT_BASE
 	bit_spin_lock(PCG_LOCK, &pc->flags);
+#else
+	spin_lock(&pc->pcg_lock);
+#endif
 }
 
 static inline void unlock_page_cgroup(struct page_cgroup *pc)
 {
+#ifndef CONFIG_PREEMPT_RT_BASE
 	bit_spin_unlock(PCG_LOCK, &pc->flags);
+#else
+	spin_unlock(&pc->pcg_lock);
+#endif
 }
 
 #else /* CONFIG_MEMCG */
@@ -102,6 +113,10 @@ static inline void __init page_cgroup_in
 {
 }
 
+static inline void page_cgroup_lock_init(struct page_cgroup *pc)
+{
+}
+
 #endif /* CONFIG_MEMCG */
 
 #include <linux/swap.h>
--- a/mm/page_cgroup.c
+++ b/mm/page_cgroup.c
@@ -13,6 +13,14 @@
 
 static unsigned long total_usage;
 
+static void page_cgroup_lock_init(struct page_cgroup *pc, int nr_pages)
+{
+#ifdef CONFIG_PREEMPT_RT_BASE
+	for (; nr_pages; nr_pages--, pc++)
+		spin_lock_init(&pc->pcg_lock);
+#endif
+}
+
 #if !defined(CONFIG_SPARSEMEM)
 
 
@@ -60,6 +68,7 @@ static int __init alloc_node_page_cgroup
 		return -ENOMEM;
 	NODE_DATA(nid)->node_page_cgroup = base;
 	total_usage += table_size;
+	page_cgroup_lock_init(base, nr_pages);
 	return 0;
 }
 
@@ -150,6 +159,8 @@ static int __meminit init_section_page_c
 		return -ENOMEM;
 	}
 
+	page_cgroup_lock_init(base, PAGES_PER_SECTION);
+
 	/*
 	 * The passed "pfn" may not be aligned to SECTION.  For the calculation
 	 * we need to apply a mask.