highmem: Allow to compile out ZONE_HIGHMEM

This effectively reduces the number of zones to 3. ZONE_HIGHMEM is only
defined if CONFIG_HIGHMEM is defined.

We drop the vm highmem counters if CONFIG_HIGHMEM is not on.

Signed-off: <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 12:54:23.402967800 -0700
+++ linux-2.6.17-mm3/include/linux/mmzone.h	2006-06-28 12:59:04.162961405 -0700
@@ -90,9 +90,14 @@ struct per_cpu_pageset {
 #define ZONE_DMA		0
 #define ZONE_DMA32		1
 #define ZONE_NORMAL		2
+#ifdef CONFIG_HIGHMEM
 #define ZONE_HIGHMEM		3
 
 #define MAX_NR_ZONES		4	/* Sync this with ZONES_SHIFT */
+#else
+#define MAX_NR_ZONES		3
+#endif
+
 #define ZONES_SHIFT		2	/* ceil(log2(MAX_NR_ZONES)) */
 
 
Index: linux-2.6.17-mm3/mm/page_alloc.c
===================================================================
--- linux-2.6.17-mm3.orig/mm/page_alloc.c	2006-06-28 12:54:23.404920804 -0700
+++ linux-2.6.17-mm3/mm/page_alloc.c	2006-06-28 12:59:28.921196945 -0700
@@ -85,7 +85,9 @@ static char *zone_names[MAX_NR_ZONES] = 
 	"DMA",
 	"DMA32",
 	"Normal",
+#ifdef CONFIG_HIGHMEM
 	"HighMem"
+#endif
 };
 
 int min_free_kbytes = 1024;
@@ -1256,8 +1258,13 @@ void si_meminfo_node(struct sysinfo *val
 
 	val->totalram = pgdat->node_present_pages;
 	val->freeram = nr_free_pages_pgdat(pgdat);
+#ifdef CONFIG_HIGHMEM
 	val->totalhigh = pgdat->node_zones[ZONE_HIGHMEM].present_pages;
 	val->freehigh = pgdat->node_zones[ZONE_HIGHMEM].free_pages;
+#else
+	val->totalhigh = 0;
+	val->freehigh = 0;
+#endif
 	val->mem_unit = PAGE_SIZE;
 }
 #endif
Index: linux-2.6.17-mm3/mm/swap_prefetch.c
===================================================================
--- linux-2.6.17-mm3.orig/mm/swap_prefetch.c	2006-06-27 09:40:25.624505390 -0700
+++ linux-2.6.17-mm3/mm/swap_prefetch.c	2006-06-28 12:59:04.178585439 -0700
@@ -277,8 +277,11 @@ static void examine_free_limits(void)
 
 		ns = &sp_stat.node[z->zone_pgdat->node_id];
 		idx = zone_idx(z);
-		ns->lowfree[idx] = z->pages_high * 3 +
-			z->lowmem_reserve[ZONE_HIGHMEM];
+		ns->lowfree[idx] = z->pages_high * 3
+#ifdef CONFIG_HIGHMEM
+		 + z->lowmem_reserve[ZONE_HIGHMEM]
+#endif
+;
 		ns->highfree[idx] = ns->lowfree[idx] + z->pages_high;
 
 		if (z->free_pages > ns->highfree[idx]) {
Index: linux-2.6.17-mm3/include/linux/vmstat.h
===================================================================
--- linux-2.6.17-mm3.orig/include/linux/vmstat.h	2006-06-27 12:07:19.842119270 -0700
+++ linux-2.6.17-mm3/include/linux/vmstat.h	2006-06-28 12:59:04.179561941 -0700
@@ -18,7 +18,11 @@
  * generated will simply be the increment of a global address.
  */
 
+#ifdef CONFIG_HIGHMEM
 #define FOR_ALL_ZONES(x) x##_DMA, x##_DMA32, x##_NORMAL, x##_HIGH
+#else
+#define FOR_ALL_ZONES(x) x##_DMA, x##_DMA32, x##_NORMAL
+#endif
 
 enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
 		FOR_ALL_ZONES(PGALLOC),
Index: linux-2.6.17-mm3/mm/vmstat.c
===================================================================
--- linux-2.6.17-mm3.orig/mm/vmstat.c	2006-06-28 12:50:30.110742333 -0700
+++ linux-2.6.17-mm3/mm/vmstat.c	2006-06-28 13:01:49.228931745 -0700
@@ -394,8 +394,13 @@ struct seq_operations fragmentation_op =
 	.show	= frag_show,
 };
 
-#define MAKE_PER_ZONE_TEXTS(x) x "_dma", x "_dma32", x "_normal", x "_high"
 
+#ifdef CONFIG_HIGHMEM
+#define MAKE_PER_ZONE_TEXTS(x) x "_dma", x "_dma32", x "_normal", x "_high"
+#else
+#define MAKE_PER_ZONE_TEXTS(x) x "_dma", x "_dma32", x "_normal"
+#endif
+ 
 static char *vmstat_text[] = {
 	/* Zoned VM counters */
 	"nr_anon_pages",