diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index dd611ef8df7a229dc2dddc95eb350dbc8cf7bc30..7d6ebe3c3b9ba43a560cd9c61ac077e567dd8569 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -191,27 +191,28 @@ static int *of_get_associativity(struct device_node *dev)
 	return (unsigned int *)get_property(dev, "ibm,associativity", NULL);
 }
 
+/* Returns nid in the range [0..MAX_NUMNODES-1], or -1 if no useful numa
+ * info is found.
+ */
 static int of_node_to_nid(struct device_node *device)
 {
-	int nid;
+	int nid = -1;
 	unsigned int *tmp;
 
 	if (min_common_depth == -1)
-		return 0;
+		goto out;
 
 	tmp = of_get_associativity(device);
-	if (tmp && (tmp[0] >= min_common_depth)) {
+	if (!tmp)
+		goto out;
+
+	if (tmp[0] >= min_common_depth)
 		nid = tmp[min_common_depth];
-	} else {
-		dbg("WARNING: no NUMA information for %s\n",
-		    device->full_name);
-		nid = 0;
-	}
 
 	/* POWER4 LPAR uses 0xffff as invalid node */
-	if (nid == 0xffff)
-		nid = 0;
-
+	if (nid == 0xffff || nid >= MAX_NUMNODES)
+		nid = -1;
+out:
 	return nid;
 }
 
@@ -301,15 +302,9 @@ static int __cpuinit numa_setup_cpu(unsigned long lcpu)
 
 	nid = of_node_to_nid(cpu);
 
-	if (nid >= num_online_nodes()) {
-		printk(KERN_ERR "WARNING: cpu %ld "
-		       "maps to invalid NUMA node %d\n",
-		       lcpu, nid);
-		nid = 0;
-	}
+	if (nid < 0 || !node_online(nid))
+		nid = any_online_node(NODE_MASK_ALL);
 out:
-	node_set_online(nid);
-
 	map_cpu_to_node(lcpu, nid);
 
 	of_node_put(cpu);
@@ -376,7 +371,7 @@ static int __init parse_numa_properties(void)
 {
 	struct device_node *cpu = NULL;
 	struct device_node *memory = NULL;
-	int max_domain = 0;
+	int default_nid = 0;
 	unsigned long i;
 
 	if (numa_enabled == 0) {
@@ -392,25 +387,26 @@ static int __init parse_numa_properties(void)
 	dbg("NUMA associativity depth for CPU/Memory: %d\n", min_common_depth);
 
 	/*
-	 * Even though we connect cpus to numa domains later in SMP init,
-	 * we need to know the maximum node id now. This is because each
-	 * node id must have NODE_DATA etc backing it.
-	 * As a result of hotplug we could still have cpus appear later on
-	 * with larger node ids. In that case we force the cpu into node 0.
+	 * Even though we connect cpus to numa domains later in SMP
+	 * init, we need to know the node ids now. This is because
+	 * each node to be onlined must have NODE_DATA etc backing it.
 	 */
-	for_each_cpu(i) {
+	for_each_present_cpu(i) {
 		int nid;
 
 		cpu = find_cpu_node(i);
+		BUG_ON(!cpu);
+		nid = of_node_to_nid(cpu);
+		of_node_put(cpu);
 
-		if (cpu) {
-			nid = of_node_to_nid(cpu);
-			of_node_put(cpu);
-
-			if (nid < MAX_NUMNODES &&
-			    max_domain < nid)
-				max_domain = nid;
-		}
+		/*
+		 * Don't fall back to default_nid yet -- we will plug
+		 * cpus into nodes once the memory scan has discovered
+		 * the topology.
+		 */
+		if (nid < 0)
+			continue;
+		node_set_online(nid);
 	}
 
 	get_n_mem_cells(&n_mem_addr_cells, &n_mem_size_cells);
@@ -439,17 +435,15 @@ static int __init parse_numa_properties(void)
 		start = read_n_cells(n_mem_addr_cells, &memcell_buf);
 		size = read_n_cells(n_mem_size_cells, &memcell_buf);
 
+		/*
+		 * Assumption: either all memory nodes or none will
+		 * have associativity properties.  If none, then
+		 * everything goes to default_nid.
+		 */
 		nid = of_node_to_nid(memory);
-
-		if (nid >= MAX_NUMNODES) {
-			printk(KERN_ERR "WARNING: memory at %lx maps "
-			       "to invalid NUMA node %d\n", start,
-			       nid);
-			nid = 0;
-		}
-
-		if (max_domain < nid)
-			max_domain = nid;
+		if (nid < 0)
+			nid = default_nid;
+		node_set_online(nid);
 
 		if (!(size = numa_enforce_memory_limit(start, size))) {
 			if (--ranges)
@@ -465,10 +459,7 @@ static int __init parse_numa_properties(void)
 			goto new_range;
 	}
 
-	for (i = 0; i <= max_domain; i++)
-		node_set_online(i);
-
-	max_domain = numa_setup_cpu(boot_cpuid);
+	numa_setup_cpu(boot_cpuid);
 
 	return 0;
 }
@@ -768,10 +759,10 @@ int hot_add_scn_to_nid(unsigned long scn_addr)
 {
 	struct device_node *memory = NULL;
 	nodemask_t nodes;
-	int nid = 0;
+	int default_nid = any_online_node(NODE_MASK_ALL);
 
 	if (!numa_enabled || (min_common_depth < 0))
-		return nid;
+		return default_nid;
 
 	while ((memory = of_find_node_by_type(memory, "memory")) != NULL) {
 		unsigned long start, size;
@@ -791,8 +782,8 @@ int hot_add_scn_to_nid(unsigned long scn_addr)
 		nid = of_node_to_nid(memory);
 
 		/* Domains not present at boot default to 0 */
-		if (!node_online(nid))
-			nid = any_online_node(NODE_MASK_ALL);
+		if (nid < 0 || !node_online(nid))
+			nid = default_nid;
 
 		if ((scn_addr >= start) && (scn_addr < (start + size))) {
 			of_node_put(memory);