diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c
index d52d6d211d9f6d644b2f2f7115b90dedf5dde34d..2b8841f85534ae199c7af971215a95d5e11a0283 100644
--- a/arch/s390/kernel/smp.c
+++ b/arch/s390/kernel/smp.c
@@ -665,7 +665,9 @@ __cpu_up(unsigned int cpu)
         cpu_lowcore->current_task = (unsigned long) idle;
         cpu_lowcore->cpu_data.cpu_nr = cpu;
 	eieio();
-	signal_processor(cpu,sigp_restart);
+
+	while (signal_processor(cpu,sigp_restart) == sigp_busy)
+		udelay(10);
 
 	while (!cpu_online(cpu))
 		cpu_relax();