Restrict special slab casing to arches using page->index

Mark the arches using page->index of slab pages.
We can then switch off the special casing for all other arches.

Signed-off-by: Christoph Lameter <clameter@sgi.com>

Index: linux-2.6.21-rc5/arch/frv/Kconfig
===================================================================
--- linux-2.6.21-rc5.orig/arch/frv/Kconfig	2007-03-29 13:47:01.000000000 -0700
+++ linux-2.6.21-rc5/arch/frv/Kconfig	2007-03-29 13:47:20.000000000 -0700
@@ -53,6 +53,10 @@ config ARCH_HAS_ILOG2_U64
 	bool
 	default y
 
+config ARCH_USES_SLAB_PAGE_INDEX
+	bool
+	default y
+
 mainmenu "Fujitsu FR-V Kernel Configuration"
 
 source "init/Kconfig"
Index: linux-2.6.21-rc5/arch/i386/Kconfig
===================================================================
--- linux-2.6.21-rc5.orig/arch/i386/Kconfig	2007-03-29 13:47:01.000000000 -0700
+++ linux-2.6.21-rc5/arch/i386/Kconfig	2007-03-29 13:47:20.000000000 -0700
@@ -79,6 +79,10 @@ config ARCH_MAY_HAVE_PC_FDC
 	bool
 	default y
 
+config ARCH_USES_SLAB_PAGE_INDEX
+	bool
+	default y
+
 config DMI
 	bool
 	default y
Index: linux-2.6.21-rc5/mm/slub.c
===================================================================
--- linux-2.6.21-rc5.orig/mm/slub.c	2007-03-29 13:47:16.000000000 -0700
+++ linux-2.6.21-rc5/mm/slub.c	2007-03-29 13:47:20.000000000 -0700
@@ -1369,6 +1369,7 @@ static int calculate_order(int size)
 	int order;
 	int rem;
 
+#ifdef CONFIG_ARCH_USES_SLAB_PAGE_INDEX
 	/*
 	 * If this is an order 0 page then there are no issues with
 	 * fragmentation. We can then create a slab with a single object.
@@ -1378,6 +1379,7 @@ static int calculate_order(int size)
 	 */
 	if (size == PAGE_SIZE)
 		return 0;
+#endif
 
 	for (order = max(slub_min_order, fls(size - 1) - PAGE_SHIFT);
 			order < MAX_ORDER; order++) {
@@ -1509,6 +1511,7 @@ int calculate_sizes(struct kmem_cache *s
 
 	tentative_size = ALIGN(size, calculate_alignment(align, flags));
 
+#ifdef CONFIG_ARCH_USES_SLAB_PAGE_INDEX
 	/*
 	 * PAGE_SIZEd slabs are special because some arches use them for
 	 * page table pages. Do not do any debugging in order to avoid
@@ -1517,6 +1520,7 @@ int calculate_sizes(struct kmem_cache *s
 	if (size == PAGE_SIZE)
 		flags &= ~(SLAB_RED_ZONE| SLAB_DEBUG_FREE | \
 			SLAB_STORE_USER | SLAB_POISON | __OBJECT_POISON);
+#endif
 
 	size = ALIGN(size, sizeof(void *));