x86: add debug of invalid per_cpu map accesses

dont crash survivable situations.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

include/asm-x86/topology.h

@@ -66,14 +66,15 @@ static inline int early_cpu_to_node(int cpu)
 
 static inline int cpu_to_node(int cpu)
 {
-#ifdef	CONFIG_DEBUG_PER_CPU_MAPS
-	if(x86_cpu_to_node_map_early_ptr) {
+#ifdef CONFIG_DEBUG_PER_CPU_MAPS
+	if (x86_cpu_to_node_map_early_ptr) {
 		printk("KERN_NOTICE cpu_to_node(%d): usage too early!\n",
 			(int)cpu);
-		BUG();
+		dump_stack();
+		return ((int *)x86_cpu_to_node_map_early_ptr)[cpu];
 	}
 #endif
-	if(per_cpu_offset(cpu))
+	if (per_cpu_offset(cpu))
 		return per_cpu(x86_cpu_to_node_map, cpu);
 	else
 		return NUMA_NO_NODE;