Slab: reduce size of alien cache to necessary nodes

The alien cache is a per cpu per node array allocated for every slab
on the system. Currently we size this array for all nodes
that the kernel does support. For IA64 this is 1024 nodes. We allocate
an array with 1024 objects even if we only boot a system with 4 nodes.

This patch uses "nr_node_ids" to determine the highest possible node
number supported by a hardware configuration and only allocates
an alien cache sized for the nodes possible.

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

Index: linux-2.6.20-rc6-mm2/mm/slab.c
===================================================================
--- linux-2.6.20-rc6-mm2.orig/mm/slab.c	2007-01-29 15:48:09.000000000 -0600
+++ linux-2.6.20-rc6-mm2/mm/slab.c	2007-01-30 13:10:31.508168575 -0600
@@ -1042,7 +1042,7 @@ static void *alternate_node_alloc(struct
 static struct array_cache **alloc_alien_cache(int node, int limit)
 {
 	struct array_cache **ac_ptr;
-	int memsize = sizeof(void *) * MAX_NUMNODES;
+	int memsize = sizeof(void *) * nr_node_ids;
 	int i;
 
 	if (limit > 1)
Index: linux-2.6.20-rc6-mm2/mm/hugetlb.c
===================================================================
--- linux-2.6.20-rc6-mm2.orig/mm/hugetlb.c	2007-01-24 20:19:28.000000000 -0600
+++ linux-2.6.20-rc6-mm2/mm/hugetlb.c	2007-01-30 13:12:44.827497675 -0600
@@ -191,11 +191,11 @@ static void update_and_free_page(struct 
 #ifdef CONFIG_HIGHMEM
 static void try_to_free_low(unsigned long count)
 {
-	int i;
+	int node;
 
-	for (i = 0; i < MAX_NUMNODES; ++i) {
+	for_each_node(node) {
 		struct page *page, *next;
-		list_for_each_entry_safe(page, next, &hugepage_freelists[i], lru) {
+		list_for_each_entry_safe(page, next, &hugepage_freelists[node], lru) {
 			if (PageHighMem(page))
 				continue;
 			list_del(&page->lru);