Memoryless nodes: Add N_CPU node state

We need the check for a node with cpu in zone reclaim.  Zone reclaim will not
allow remote zone reclaim if a node has a cpu.

[Lee.Schermerhorn@hp.com: Move setup of N_CPU node state mask]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Tested-by:  Lee Schermerhorn <lee.schermerhorn@hp.com>
Acked-by: Bob Picco <bob.picco@hp.com>
Cc: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@skynet.ie>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/nodemask.h

@@ -349,6 +349,7 @@ enum node_states {
 #else
 	N_HIGH_MEMORY = N_NORMAL_MEMORY,
 #endif
+	N_CPU,		/* The node has one or more cpus */
 	NR_NODE_STATES
 };
 

mm/page_alloc.c

@@ -2353,14 +2353,17 @@ static struct per_cpu_pageset boot_pageset[NR_CPUS];
 static int __cpuinit process_zones(int cpu)
 {
 	struct zone *zone, *dzone;
+	int node = cpu_to_node(cpu);
+
+	node_set_state(node, N_CPU);	/* this node has a cpu */
 
 	for_each_zone(zone) {
 
 		if (!populated_zone(zone))
 			continue;
 
 		zone_pcp(zone, cpu) = kmalloc_node(sizeof(struct per_cpu_pageset),
-					 GFP_KERNEL, cpu_to_node(cpu));
+					 GFP_KERNEL, node);
 		if (!zone_pcp(zone, cpu))
 			goto bad;
 

mm/vmscan.c

@@ -1853,7 +1853,6 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
 
 int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
 {
-	cpumask_t mask;
 	int node_id;
 
 	/*
@@ -1890,8 +1889,7 @@ int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
 	 * as wide as possible.
 	 */
 	node_id = zone_to_nid(zone);
-	mask = node_to_cpumask(node_id);
-	if (!cpus_empty(mask) && node_id != numa_node_id())
+	if (node_state(node_id, N_CPU) && node_id != numa_node_id())
 		return 0;
 	return __zone_reclaim(zone, gfp_mask, order);
 }