diff --git a/arch/s390/crypto/prng.c b/arch/s390/crypto/prng.c
index 0cfefddd8375..c238ee4aa038 100644
--- a/arch/s390/crypto/prng.c
+++ b/arch/s390/crypto/prng.c
@@ -6,6 +6,7 @@
 #include <linux/fs.h>
 #include <linux/init.h>
 #include <linux/kernel.h>
+#include <linux/smp_lock.h>
 #include <linux/miscdevice.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
@@ -48,6 +49,7 @@ static unsigned char parm_block[32] = {
 
 static int prng_open(struct inode *inode, struct file *file)
 {
+	cycle_kernel_lock();
 	return nonseekable_open(inode, file);
 }