diff --git a/kernel/up.c b/kernel/up.c
index 53144d0562522e6d00824073f65ffa9926ae6261..c6f323dcd45bb9efe1401b1b7893350667305493 100644
--- a/kernel/up.c
+++ b/kernel/up.c
@@ -14,7 +14,8 @@ int smp_call_function_single(int cpu, void (*func) (void *info), void *info,
 {
 	unsigned long flags;
 
-	WARN_ON(cpu != 0);
+	if (cpu != 0)
+		return -ENXIO;
 
 	local_irq_save(flags);
 	func(info);