diff --git a/arch/s390/boot/startup.c b/arch/s390/boot/startup.c
index abe6e6c0ab98..6087d38c7235 100644
--- a/arch/s390/boot/startup.c
+++ b/arch/s390/boot/startup.c
@@ -234,6 +234,8 @@ static unsigned long get_vmem_size(unsigned long identity_size,
 	vsize = round_up(SZ_2G + max_mappable, rte_size) +
 		round_up(vmemmap_size, rte_size) +
 		FIXMAP_SIZE + MODULES_LEN + KASLR_LEN;
+	if (IS_ENABLED(CONFIG_KMSAN))
+		vsize += MODULES_LEN * 2;
 	return size_add(vsize, vmalloc_size);
 }