x86/uv: fix init of memory-less nodes

Add support for nodes that have cpus but no memory.
The current code was failing to add these nodes
to the nodes_present_map.

v2: Fixes case caught by David Rientjes - missed support
    for the x2apic SRAT table.

[ Impact: fix potential boot crash on memory-less UV nodes. ]
Reported-by: David Rientjes <rientjes@google.com>
Signed-off-by: Jack Steiner <steiner@sgi.com>
LKML-Reference: <20090417142242.GA23743@sgi.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

arch/x86/mm/srat_64.c

@@ -28,6 +28,7 @@ int acpi_numa __initdata;
 static struct acpi_table_slit *acpi_slit;
 
 static nodemask_t nodes_parsed __initdata;
+static nodemask_t cpu_nodes_parsed __initdata;
 static struct bootnode nodes[MAX_NUMNODES] __initdata;
 static struct bootnode nodes_add[MAX_NUMNODES];
 static int found_add_area __initdata;
@@ -141,6 +142,7 @@ acpi_numa_x2apic_affinity_init(struct acpi_srat_x2apic_cpu_affinity *pa)
 
 	apic_id = pa->apic_id;
 	apicid_to_node[apic_id] = node;
+	node_set(node, cpu_nodes_parsed);
 	acpi_numa = 1;
 	printk(KERN_INFO "SRAT: PXM %u -> APIC %u -> Node %u\n",
 	       pxm, apic_id, node);
@@ -174,6 +176,7 @@ acpi_numa_processor_affinity_init(struct acpi_srat_cpu_affinity *pa)
 	else
 		apic_id = pa->apic_id;
 	apicid_to_node[apic_id] = node;
+	node_set(node, cpu_nodes_parsed);
 	acpi_numa = 1;
 	printk(KERN_INFO "SRAT: PXM %u -> APIC %u -> Node %u\n",
 	       pxm, apic_id, node);
@@ -402,7 +405,8 @@ int __init acpi_scan_nodes(unsigned long start, unsigned long end)
 		return -1;
 	}
 
-	node_possible_map = nodes_parsed;
+	/* Account for nodes with cpus and no memory */
+	nodes_or(node_possible_map, nodes_parsed, cpu_nodes_parsed);
 
 	/* Finally register nodes */
 	for_each_node_mask(i, node_possible_map)