diff --git a/[refs] b/[refs]
index fee14af3ab80..84a62ea3e35d 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: a11940978bd598e65996b4f807cf4904793f7025
+refs/heads/master: 8bdafa39a47265bc029838b35cc6585f69224afa
diff --git a/trunk/arch/powerpc/mm/mmu_context_hash64.c b/trunk/arch/powerpc/mm/mmu_context_hash64.c
index 3bafc3deca6d..4ff587e38250 100644
--- a/trunk/arch/powerpc/mm/mmu_context_hash64.c
+++ b/trunk/arch/powerpc/mm/mmu_context_hash64.c
@@ -136,8 +136,8 @@ int use_cop(unsigned long acop, struct mm_struct *mm)
 	if (!mm || !acop)
 		return -EINVAL;
 
-	/* We need to make sure mm_users doesn't change */
-	down_read(&mm->mmap_sem);
+	/* The page_table_lock ensures mm_users won't change under us */
+	spin_lock(&mm->page_table_lock);
 	spin_lock(mm->context.cop_lockp);
 
 	if (mm->context.cop_pid == COP_PID_NONE) {
@@ -164,7 +164,7 @@ int use_cop(unsigned long acop, struct mm_struct *mm)
 
 out:
 	spin_unlock(mm->context.cop_lockp);
-	up_read(&mm->mmap_sem);
+	spin_unlock(&mm->page_table_lock);
 
 	return ret;
 }
@@ -185,8 +185,8 @@ void drop_cop(unsigned long acop, struct mm_struct *mm)
 	if (WARN_ON_ONCE(!mm))
 		return;
 
-	/* We need to make sure mm_users doesn't change */
-	down_read(&mm->mmap_sem);
+	/* The page_table_lock ensures mm_users won't change under us */
+	spin_lock(&mm->page_table_lock);
 	spin_lock(mm->context.cop_lockp);
 
 	mm->context.acop &= ~acop;
@@ -213,7 +213,7 @@ void drop_cop(unsigned long acop, struct mm_struct *mm)
 	}
 
 	spin_unlock(mm->context.cop_lockp);
-	up_read(&mm->mmap_sem);
+	spin_unlock(&mm->page_table_lock);
 }
 EXPORT_SYMBOL_GPL(drop_cop);