--- x/kernel/sched/stats.c
+++ y/kernel/sched/stats.c
@@ -192,7 +192,7 @@ static void *schedstat_start(struct seq_
 
 	n--;
 
-	if (n > 0)
+	if (n > 0 && n -1 < nr_cpu_ids)
 		n = cpumask_next(n - 1, cpu_online_mask);
 	else
 		n = cpumask_first(cpu_online_mask);