Index: linux-2.6/include/linux/mm_types.h
===================================================================
--- linux-2.6.orig/include/linux/mm_types.h
+++ linux-2.6/include/linux/mm_types.h
@@ -23,27 +23,20 @@ struct page {
 					 * to show when page is mapped
 					 * & limit reverse map searches.
 					 */
-	union {
-	    struct {
-		unsigned long private;		/* Mapping-private opaque data:
-					 	 * usually used for buffer_heads
-						 * if PagePrivate set; used for
-						 * swp_entry_t if PageSwapCache;
-						 * indicates order in the buddy
-						 * system if PG_buddy is set.
-						 */
-		struct address_space *mapping;	/* If low bit clear, points to
-						 * inode address_space, or NULL.
-						 * If page mapped as anonymous
-						 * memory, low bit is set, and
-						 * it points to anon_vma object:
-						 * see PAGE_MAPPING_ANON below.
-						 */
-	    };
-#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
-	    spinlock_t ptl;
-#endif
-	};
+	unsigned long private;		/* Mapping-private opaque data:
+				 	 * usually used for buffer_heads
+					 * if PagePrivate set; used for
+					 * swp_entry_t if PageSwapCache;
+					 * indicates order in the buddy
+					 * system if PG_buddy is set.
+					 */
+	struct address_space *mapping;	/* If low bit clear, points to
+					 * inode address_space, or NULL.
+					 * If page mapped as anonymous
+					 * memory, low bit is set, and
+					 * it points to anon_vma object:
+					 * see PAGE_MAPPING_ANON below.
+					 */
 	pgoff_t index;			/* Our offset within mapping. */
 	struct list_head lru;		/* Pageout list, eg. active_list
 					 * protected by zone->lru_lock !
@@ -64,4 +57,45 @@ struct page {
 #endif /* WANT_PAGE_VIRTUAL */
 };
 
+/*
+ * We can provide alternate delcarations for 'struct page', instead of
+ * overloading fields that we would like to use for non-pagecache (eg.
+ * page tables or slab pages). However flags and _count must always be
+ * in the correct position, and not overloaded, because they might be
+ * accessed by thing without a direct reference (eg. buddy allocator,
+ * swsusp). So flags and _count get defined for us, and our struct is
+ * automatically padded out to the size of struct page. A compile time
+ * check ensures that this size isn't exceeded.
+ */
+#define DEFINE_PAGE_STRUCT(name)	\
+struct name {				\
+	union {				\
+		struct {		\
+			unsigned long flags; \
+			atomic_t _count; \
+			struct
+
+#define END_PAGE_STRUCT(name)		\
+			;		\
+		};			\
+		struct page ___page;	\
+	};				\
+};					\
+					\
+static inline void struct_##name##_build_bug_on(void) \
+{					\
+	BUILD_BUG_ON(sizeof(struct name) > sizeof(struct page)); \
+}
+
+DEFINE_PAGE_STRUCT(pt_page) {
+#if NR_CPUS >= CONFIG_SPLIT_PTLOCK_CPUS
+	spinlock_t ptl;
+#endif
+} END_PAGE_STRUCT(pt_page)
+
+DEFINE_PAGE_STRUCT(buddy_page) {
+	unsigned int order;
+	struct list_head list;
+} END_PAGE_STRUCT(buddy_page)
+
 #endif /* _LINUX_MM_TYPES_H */
Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c
+++ linux-2.6/mm/slab.c
@@ -446,6 +446,11 @@ struct kmem_cache {
 #endif
 };
 
+DEFINE_PAGE_STRUCT(slab_page) {
+	struct list_head *cache;
+	struct list_head *slab;
+} END_PAGE_STRUCT(slab_page)
+
 #define CFLGS_OFF_SLAB		(0x80000000UL)
 #define	OFF_SLAB(x)	((x)->flags & CFLGS_OFF_SLAB)