diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index 0a9a6da21e74..db21f68aaef0 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -83,7 +83,13 @@ extern const struct cpumask *const cpu_active_mask;
 
 #if NR_CPUS > 1
 #define num_online_cpus()	cpumask_weight(cpu_online_mask)
-#define num_possible_cpus()	cpumask_weight(cpu_possible_mask)
+/*
+ * For platforms with discontig CPU numbering, the weight of the possible
+ * bitmask may be less than the highest numbered CPU. Return the max of
+ * the two, to prevent accidentical bugs.
+ */
+#define num_possible_cpus()	\
+	max_t(unsigned int, cpumask_weight(cpu_possible_mask), nr_cpu_ids)
 #define num_present_cpus()	cpumask_weight(cpu_present_mask)
 #define num_active_cpus()	cpumask_weight(cpu_active_mask)
 #define cpu_online(cpu)		cpumask_test_cpu((cpu), cpu_online_mask)