diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h
index cd415b733c2a..63661de67ad4 100644
--- a/include/linux/cpumask.h
+++ b/include/linux/cpumask.h
@@ -130,6 +130,11 @@ static inline unsigned int cpumask_first(const struct cpumask *srcp)
 	return 0;
 }
 
+static inline unsigned int cpumask_last(const struct cpumask *srcp)
+{
+	return 0;
+}
+
 /* Valid inputs for n are -1 and 0. */
 static inline unsigned int cpumask_next(int n, const struct cpumask *srcp)
 {
@@ -178,6 +183,17 @@ static inline unsigned int cpumask_first(const struct cpumask *srcp)
 	return find_first_bit(cpumask_bits(srcp), nr_cpumask_bits);
 }
 
+/**
+ * cpumask_last - get the last CPU in a cpumask
+ * @srcp:	- the cpumask pointer
+ *
+ * Returns	>= nr_cpumask_bits if no CPUs set.
+ */
+static inline unsigned int cpumask_last(const struct cpumask *srcp)
+{
+	return find_last_bit(cpumask_bits(srcp), nr_cpumask_bits);
+}
+
 unsigned int cpumask_next(int n, const struct cpumask *srcp);
 
 /**
diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c
index e50450c2fed8..e3d31b0880dc 100644
--- a/kernel/sched/topology.c
+++ b/kernel/sched/topology.c
@@ -476,8 +476,8 @@ static int __init isolated_cpu_setup(char *str)
 
 	alloc_bootmem_cpumask_var(&cpu_isolated_map);
 	ret = cpulist_parse(str, cpu_isolated_map);
-	if (ret) {
-		pr_err("sched: Error, all isolcpus= values must be between 0 and %u\n", nr_cpu_ids);
+	if (ret || cpumask_last(cpu_isolated_map) >= nr_cpu_ids) {
+		pr_err("sched: Error, all isolcpus= values must be between 0 and %u - ignoring them.\n", nr_cpu_ids-1);
 		return 0;
 	}
 	return 1;