highmem: CONFIG_HIGHMEM cleanup

- Make sure that macros unconditionally return false if CONFIG_HIGHMEM
  is not defined. This will avoid generating code for highmem when the
  kernel is compiled without highmem support.

- Define arrays of lowmem resources based on ZONE_NORMAL and not on MAX_NR_ZONES

- Remove some uses of ZONE_HIGHMEM that are not necessary.

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

Index: linux-2.6.17-mm3/include/linux/mmzone.h
===================================================================
--- linux-2.6.17-mm3.orig/include/linux/mmzone.h	2006-06-28 12:48:49.250763069 -0700
+++ linux-2.6.17-mm3/include/linux/mmzone.h	2006-06-28 12:54:23.402967800 -0700
@@ -376,9 +376,14 @@ static inline int populated_zone(struct 
 
 static inline int is_highmem_idx(int idx)
 {
+#ifdef CONFIG_HIGHMEM
 	return (idx == ZONE_HIGHMEM);
+#else
+	return 0;
+#endif
 }
 
+
 static inline int is_normal_idx(int idx)
 {
 	return (idx == ZONE_NORMAL);
@@ -392,7 +397,11 @@ static inline int is_normal_idx(int idx)
  */
 static inline int is_highmem(struct zone *zone)
 {
+#ifdef CONFIG_HIGHMEM
 	return zone == zone->zone_pgdat->node_zones + ZONE_HIGHMEM;
+#else
+	return 0;
+#endif
 }
 
 static inline int is_normal(struct zone *zone)
@@ -415,7 +424,7 @@ struct ctl_table;
 struct file;
 int min_free_kbytes_sysctl_handler(struct ctl_table *, int, struct file *, 
 					void __user *, size_t *, loff_t *);
-extern int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1];
+extern int sysctl_lowmem_reserve_ratio[ZONE_NORMAL + 1];
 int lowmem_reserve_ratio_sysctl_handler(struct ctl_table *, int, struct file *,
 					void __user *, size_t *, loff_t *);
 int percpu_pagelist_fraction_sysctl_handler(struct ctl_table *, int, struct file *,
Index: linux-2.6.17-mm3/mm/page_alloc.c
===================================================================
--- linux-2.6.17-mm3.orig/mm/page_alloc.c	2006-06-28 12:49:33.558572405 -0700
+++ linux-2.6.17-mm3/mm/page_alloc.c	2006-06-28 12:54:23.404920804 -0700
@@ -70,7 +70,7 @@ static void __free_pages_ok(struct page 
  * TBD: should special case ZONE_DMA32 machines here - in those we normally
  * don't need any ZONE_NORMAL reservation
  */
-int sysctl_lowmem_reserve_ratio[MAX_NR_ZONES-1] = { 256, 256, 32 };
+int sysctl_lowmem_reserve_ratio[ZONE_NORMAL + 1] = { 256, 256, 32 };
 
 EXPORT_SYMBOL(totalram_pages);
 
@@ -1385,8 +1385,7 @@ static int __meminit build_zonelists_nod
 			struct zonelist *zonelist, int nr_zones, int zone_type)
 {
 	struct zone *zone;
-
-	BUG_ON(zone_type > ZONE_HIGHMEM);
+	BUG_ON(zone_type >= MAX_NR_ZONES);
 
 	do {
 		zone = pgdat->node_zones + zone_type;
@@ -1406,8 +1405,10 @@ static int __meminit build_zonelists_nod
 static inline int highest_zone(int zone_bits)
 {
 	int res = ZONE_NORMAL;
+#ifdef CONFIG_HIGHMEM
 	if (zone_bits & (__force int)__GFP_HIGHMEM)
 		res = ZONE_HIGHMEM;
+#endif
 	if (zone_bits & (__force int)__GFP_DMA32)
 		res = ZONE_DMA32;
 	if (zone_bits & (__force int)__GFP_DMA)
@@ -2021,7 +2022,7 @@ static void __meminit free_area_init_cor
 		if (zholes_size)
 			realsize -= zholes_size[j];
 
-		if (j < ZONE_HIGHMEM)
+		if (!is_highmem_idx(j))
 			nr_kernel_pages += realsize;
 		nr_all_pages += realsize;