mm: use two zonelist that are filtered by GFP mask

Currently a node has two sets of zonelists, one for each zone type in the
system and a second set for GFP_THISNODE allocations.  Based on the zones
allowed by a gfp mask, one of these zonelists is selected.  All of these
zonelists consume memory and occupy cache lines.

This patch replaces the multiple zonelists per-node with two zonelists.  The
first contains all populated zones in the system, ordered by distance, for
fallback allocations when the target/preferred node has no free pages.  The
second contains all populated zones in the node suitable for GFP_THISNODE
allocations.

An iterator macro is introduced called for_each_zone_zonelist() that interates
through each zone allowed by the GFP flags in the selected zonelist.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/parisc/mm/init.c

@@ -603,15 +603,18 @@ void show_mem(void)
 #ifdef CONFIG_DISCONTIGMEM
 	{
 		struct zonelist *zl;
-		int i, j, k;
+		int i, j;
 
 		for (i = 0; i < npmem_ranges; i++) {
+			zl = node_zonelist(i);
 			for (j = 0; j < MAX_NR_ZONES; j++) {
-				zl = NODE_DATA(i)->node_zonelists + j;
+				struct zone **z;
+				struct zone *zone;
 
 				printk("Zone list for zone %d on node %d: ", j, i);
-				for (k = 0; zl->zones[k] != NULL; k++) 
-					printk("[%d/%s] ", zone_to_nid(zl->zones[k]), zl->zones[k]->name);
+				for_each_zone_zonelist(zone, z, zl, j)
+					printk("[%d/%s] ", zone_to_nid(zone),
+								zone->name);
 				printk("\n");
 			}
 		}