Index: linux-2.6/include/linux/page-flags.h
===================================================================
--- linux-2.6.orig/include/linux/page-flags.h	2007-04-24 10:39:56.000000000 +1000
+++ linux-2.6/include/linux/page-flags.h	2007-05-03 08:38:53.000000000 +1000
@@ -91,6 +91,8 @@
 #define PG_nosave_free		18	/* Used for system suspend/resume */
 #define PG_buddy		19	/* Page is free, on buddy lists */
 
+#define PG_waiters		20	/* Page has PG_locked waiters */
+
 /* PG_owner_priv_1 users should have descriptive aliases */
 #define PG_checked		PG_owner_priv_1 /* Used by some filesystems */
 
Index: linux-2.6/include/linux/pagemap.h
===================================================================
--- linux-2.6.orig/include/linux/pagemap.h	2007-04-24 10:39:56.000000000 +1000
+++ linux-2.6/include/linux/pagemap.h	2007-05-03 08:35:08.000000000 +1000
@@ -141,7 +141,7 @@
 static inline void lock_page(struct page *page)
 {
 	might_sleep();
-	if (TestSetPageLocked(page))
+	if (unlikely(TestSetPageLocked(page)))
 		__lock_page(page);
 }
 
@@ -152,7 +152,7 @@
 static inline void lock_page_nosync(struct page *page)
 {
 	might_sleep();
-	if (TestSetPageLocked(page))
+	if (unlikely(TestSetPageLocked(page)))
 		__lock_page_nosync(page);
 }
 	
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c	2007-05-02 15:00:26.000000000 +1000
+++ linux-2.6/mm/filemap.c	2007-05-03 08:34:32.000000000 +1000
@@ -532,11 +532,13 @@
  */
 void fastcall unlock_page(struct page *page)
 {
+	VM_BUG_ON(!PageLocked(page));
 	smp_mb__before_clear_bit();
-	if (!TestClearPageLocked(page))
-		BUG();
-	smp_mb__after_clear_bit(); 
-	wake_up_page(page, PG_locked);
+	ClearPageLocked(page);
+	if (unlikely(test_bit(PG_waiters, &page->flags))) {
+		clear_bit(PG_waiters, &page->flags);
+		wake_up_page(page, PG_locked);
+	}
 }
 EXPORT_SYMBOL(unlock_page);
 
@@ -568,6 +570,11 @@
 {
 	DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
 
+	set_bit(PG_waiters, &page->flags);
+	if (unlikely(!TestSetPageLocked(page))) {
+		clear_bit(PG_waiters, &page->flags);
+		return;
+	}
 	__wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
 							TASK_UNINTERRUPTIBLE);
 }