2 files changed, 29 insertions, 4 deletions

diff --git a/arch/x86/kernel/setup_percpu.c b/arch/x86/kernel/setup_percpu.c
index 7068f95cccc6..43aca2de624a 100644
--- a/arch/x86/kernel/setup_percpu.c
+++ b/arch/x86/kernel/setup_percpu.c
@@ -346,6 +346,10 @@ int early_cpu_to_node(int cpu)
         return per_cpu(x86_cpu_to_node_map, cpu);
 }
 
+
+/* empty cpumask */
+static const cpumask_t cpu_mask_none;
+
 /*
  * Returns a pointer to the bitmask of CPUs on Node 'node'.
  */
@@ -358,13 +362,23 @@ cpumask_t *_node_to_cpumask_ptr(int node)
                 dump_stack();
                 return &cpu_online_map;
         }
-        BUG_ON(node >= nr_node_ids);
-        return &node_to_cpumask_map[node];
+        if (node >= nr_node_ids) {
+                printk(KERN_WARNING
+                        "_node_to_cpumask_ptr(%d): node > nr_node_ids(%d)\n",
+                        node, nr_node_ids);
+                dump_stack();
+                return (cpumask_t *)&cpu_mask_none;
+        }
+        return (cpumask_t *)&node_to_cpumask_map[node];
 }
 EXPORT_SYMBOL(_node_to_cpumask_ptr);
 
 /*
  * Returns a bitmask of CPUs on Node 'node'.
+ *
+ * Side note: this function creates the returned cpumask on the stack
+ * so with a high NR_CPUS count, excessive stack space is used.  The
+ * node_to_cpumask_ptr function should be used whenever possible.
  */
 cpumask_t node_to_cpumask(int node)
 {
@@ -374,7 +388,13 @@ cpumask_t node_to_cpumask(int node)
                 dump_stack();
                 return cpu_online_map;
         }
-        BUG_ON(node >= nr_node_ids);
+        if (node >= nr_node_ids) {
+                printk(KERN_WARNING
+                        "node_to_cpumask(%d): node > nr_node_ids(%d)\n",
+                        node, nr_node_ids);
+                dump_stack();
+                return cpu_mask_none;
+        }
         return node_to_cpumask_map[node];
 }
 EXPORT_SYMBOL(node_to_cpumask);
diff --git a/include/asm-x86/topology.h b/include/asm-x86/topology.h
index 1f97758de4ab..98e5f17ea856 100644
--- a/include/asm-x86/topology.h
+++ b/include/asm-x86/topology.h
@@ -57,7 +57,12 @@ static inline int cpu_to_node(int cpu)
 }
 #define early_cpu_to_node(cpu)  cpu_to_node(cpu)
 
-/* Returns a bitmask of CPUs on Node 'node'. */
+/* Returns a bitmask of CPUs on Node 'node'.
+ *
+ * Side note: this function creates the returned cpumask on the stack
+ * so with a high NR_CPUS count, excessive stack space is used.  The
+ * node_to_cpumask_ptr function should be used whenever possible.
+ */
 static inline cpumask_t node_to_cpumask(int node)
 {
         return node_to_cpumask_map[node];