[PATCH V3 0/2] pseries/nodes: Fix issues with memoryless nodes

@@ -892,6 +892,36 @@ static void __init setup_node_data(int nid, u64 start_pfn, u64 end_pfn)
 	NODE_DATA(nid)->node_spanned_pages = spanned_pages;
 }
 
+static void __init find_possible_nodes(void)
+{
+	struct device_node *rtas;
+	u32 numnodes, i;
+
+	if (min_common_depth <= 0)
+		return;
+
+	rtas = of_find_node_by_path("/rtas");
+	if (!rtas)
+		return;
+
+	if (of_property_read_u32_index(rtas,
+				"ibm,max-associativity-domains",
+				min_common_depth, &numnodes))
+		goto out;
+
+	pr_info("numa: Nodes = %d (mcd = %d)\n", numnodes,
+		min_common_depth);
+
+	for (i = 0; i < numnodes; i++) {
+		if (!node_possible(i))
+			node_set(i, node_possible_map);
+	}
+
+out:
+	if (rtas)
+		of_node_put(rtas);
+}
+
 void __init initmem_init(void)
 {
 	int nid, cpu;

@@ -905,12 +935,15 @@ void __init initmem_init(void)
 	memblock_dump_all();
 
 	/*
-	 * Reduce the possible NUMA nodes to the online NUMA nodes,
-	 * since we do not support node hotplug. This ensures that  we
-	 * lower the maximum NUMA node ID to what is actually present.
+	 * Modify the set of possible NUMA nodes to reflect information
+	 * available about the set of online nodes, and the set of nodes
+	 * that we expect to make use of for this platform's affinity
+	 * calculations.
 	 */
 	nodes_and(node_possible_map, node_possible_map, node_online_map);
 
+	find_possible_nodes();
+
 	for_each_online_node(nid) {
 		unsigned long start_pfn, end_pfn;
 

@@ -551,7 +551,7 @@ static int numa_setup_cpu(unsigned long lcpu)
 	nid = of_node_to_nid_single(cpu);
 
 out_present:
-	if (nid < 0 || !node_online(nid))
+	if (nid < 0 || !node_possible(nid))
 		nid = first_online_node;
 
 	map_cpu_to_node(lcpu, nid);

@@ -1311,6 +1311,35 @@ static long vphn_get_associativity(unsigned long cpu,
 	return rc;
 }
 
+static int verify_node_preparation(int nid)
+{
+	/*
+	 * Need to allocate/initialize NODE_DATA from a node with
+	 * memory (see memblock_alloc_try_nid).  Code executed after
+	 * boot (like local_memory_node) often does not know enough
+	 * to recover fully for memoryless nodes. 
+	 */
+	if (NODE_DATA(nid) == NULL) {
+		int ret;
+		printk(KERN_INFO "%s:%d node %d (%d)\n", __FUNCTION__, __LINE__, nid, first_online_node);
+		setup_node_data(nid, 0, 0);
+		printk(KERN_INFO "%s:%d node %d (%d)\n", __FUNCTION__, __LINE__, nid, first_online_node);
+		ret = try_online_node(nid);
+		printk(KERN_INFO "%s:%d node %d (%d) %d %p\n", __FUNCTION__, __LINE__, nid, first_online_node, ret, NODE_DATA(nid));
+
+		/*
+		 * Node structures successfully initialized, but
+		 * we still need the node to be offline.
+		 */
+		node_set_offline(nid);
+	}
+
+	if (NODE_DATA(nid)->node_spanned_pages == 0)
+		return first_online_node;
+
+	return nid;
+}
+
 /*
  * Update the CPU maps and sysfs entries for a single CPU when its NUMA
  * characteristics change. This function doesn't perform any locking and is

@@ -1419,9 +1448,11 @@ int numa_update_cpu_topology(bool cpus_locked)
 		/* Use associativity from first thread for all siblings */
 		vphn_get_associativity(cpu, associativity);
 		new_nid = associativity_to_nid(associativity);
-		if (new_nid < 0 || !node_online(new_nid))
+		if (new_nid < 0 || !node_possible(new_nid))
 			new_nid = first_online_node;
 
+		new_nid = verify_node_preparation(new_nid);
+
 		if (new_nid == numa_cpu_lookup_table[cpu]) {
 			cpumask_andnot(&cpu_associativity_changes_mask,
 					&cpu_associativity_changes_mask,