Index: linux-2.6/arch/parisc/kernel/cache.c
===================================================================
--- linux-2.6.orig/arch/parisc/kernel/cache.c	2007-06-27 19:59:08.000000000 -0700
+++ linux-2.6/arch/parisc/kernel/cache.c	2007-06-27 19:59:31.000000000 -0700
@@ -339,7 +339,7 @@
 
 void flush_dcache_page(struct page *page)
 {
-	struct address_space *mapping = page_mapping(page);
+	struct address_space *mapping = any_page_mapping(page);
 	struct vm_area_struct *mpnt;
 	struct prio_tree_iter iter;
 	unsigned long offset;
Index: linux-2.6/arch/sparc64/mm/init.c
===================================================================
--- linux-2.6.orig/arch/sparc64/mm/init.c	2007-06-27 20:01:13.000000000 -0700
+++ linux-2.6/arch/sparc64/mm/init.c	2007-06-27 20:02:49.000000000 -0700
@@ -339,7 +339,7 @@
 
 	this_cpu = get_cpu();
 
-	mapping = page_mapping(page);
+	mapping = any_page_mapping(page);
 	if (mapping && !mapping_mapped(mapping)) {
 		int dirty = test_bit(PG_dcache_dirty, &page->flags);
 		if (dirty) {
Index: linux-2.6/include/linux/mm.h
===================================================================
--- linux-2.6.orig/include/linux/mm.h	2007-06-27 19:51:17.000000000 -0700
+++ linux-2.6/include/linux/mm.h	2007-06-27 20:22:54.000000000 -0700
@@ -590,6 +590,9 @@
  * page->mapping points to its anon_vma, not to a struct address_space;
  * with the PAGE_MAPPING_ANON bit set to distinguish it.
  *
+ * Similarly on a slab page the mapping points to the kmem_cache structure.
+ * PageSlab is set in page flags to distinguish it.
+ *
  * Please note that, confusingly, "page_mapping" refers to the inode
  * address_space which maps the page from disk; whereas "page_mapped"
  * refers to user virtual address space into which the page is mapped.
@@ -597,24 +600,40 @@
 #define PAGE_MAPPING_ANON	1
 
 extern struct address_space swapper_space;
-static inline struct address_space *page_mapping(struct page *page)
+
+static inline int PageAnon(struct page *page)
 {
-	struct address_space *mapping = page->mapping;
+	return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
+}
 
+/*
+ * Determine the mapping of a regular page.
+ */
+static inline struct address_space *page_mapping(struct page *page)
+{
 	if (unlikely(PageSwapCache(page)))
-		mapping = &swapper_space;
-#ifdef CONFIG_SLUB
-	else if (unlikely(PageSlab(page)))
-		mapping = NULL;
-#endif
-	else if (unlikely((unsigned long)mapping & PAGE_MAPPING_ANON))
-		mapping = NULL;
-	return mapping;
+		return &swapper_space;
+	else if (unlikely(PageAnon(page)))
+		return NULL;
+	return page->mapping;
 }
 
-static inline int PageAnon(struct page *page)
+/*
+ * Determine the mapping of an arbitrary page including slab pages.
+ *
+ * There are cases in the kernel where we need to determine the mapping
+ * of a page regardless of what type of page it is. For example
+ * flush_dcache_page may be passed a page struct that was determined
+ * from a slab object sinc the scatter gather lists may occasionally
+ * be filled with objects allocated via the slab allocator (yuck).
+ */
+static inline struct address_space *any_page_mapping(struct page *page)
 {
-	return ((unsigned long)page->mapping & PAGE_MAPPING_ANON) != 0;
+#ifdef CONFIG_SLUB
+	if (unlikely(PageSlab(page)))
+		return NULL;
+#endif
+	return page_mapping(page);
 }
 
 /*
Index: linux-2.6/arch/xtensa/mm/init.c
===================================================================
--- linux-2.6.orig/arch/xtensa/mm/init.c	2007-06-27 20:03:39.000000000 -0700
+++ linux-2.6/arch/xtensa/mm/init.c	2007-06-27 20:03:52.000000000 -0700
@@ -433,7 +433,7 @@
 void flush_dcache_page(struct page *page)
 {
 	unsigned long addr = __pa(page_address(page));
-	struct address_space *mapping = page_mapping(page);
+	struct address_space *mapping = any_page_mapping(page);
 
 	__flush_invalidate_dcache_page_phys(addr);
 
Index: linux-2.6/arch/arm/mm/flush.c
===================================================================
--- linux-2.6.orig/arch/arm/mm/flush.c	2007-06-27 20:11:55.000000000 -0700
+++ linux-2.6/arch/arm/mm/flush.c	2007-06-27 20:12:00.000000000 -0700
@@ -188,7 +188,7 @@
  */
 void flush_dcache_page(struct page *page)
 {
-	struct address_space *mapping = page_mapping(page);
+	struct address_space *mapping = any_page_mapping(page);
 
 #ifndef CONFIG_SMP
 	if (mapping && !mapping_mapped(mapping))