Add slub_max_order

Avoid slabs getting to large. Do no longer enforce slub_min_objects
if the slab gets bigger than slub_max_order. That way we may get back
to single order slabs.

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

Index: linux-2.6.21-rc3/mm/slub.c
===================================================================
--- linux-2.6.21-rc3.orig/mm/slub.c	2007-03-10 13:14:06.000000000 -0800
+++ linux-2.6.21-rc3/mm/slub.c	2007-03-10 13:14:11.000000000 -0800
@@ -1211,6 +1211,7 @@ static __always_inline struct page *get_
  * take the list_lock.
  */
 static int slub_min_order = 0;
+static int slub_max_order = 4;
 
 /*
  * Minimum number of objects per slab. This is necessary in order to
@@ -1249,7 +1250,11 @@ static int calculate_order(int size)
 			order < MAX_ORDER; order++) {
 		unsigned long slab_size = PAGE_SIZE << order;
 
-		if (slab_size < slub_min_objects * size)
+		if (slub_max_order > order &&
+				slab_size < slub_min_objects * size)
+			continue;
+
+		if (slab_size < size)
 			continue;
 
 		rem = slab_size % size;
@@ -1637,6 +1642,15 @@ static int __init setup_slub_min_order(c
 
 __setup("slub_min_order=", setup_slub_min_order);
 
+static int __init setup_slub_max_order(char *str)
+{
+	get_option (&str, &slub_max_order);
+
+	return 1;
+}
+
+__setup("slub_max_order=", setup_slub_max_order);
+
 static int __init setup_slub_min_objects(char *str)
 {
 	get_option (&str, &slub_min_objects);