diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 427b534d60d2..dcc1dd96911a 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -1146,8 +1146,16 @@ int __init __weak early_init_dt_mark_hotplug_memory_arch(u64 base, u64 size)
 int __init __weak early_init_dt_reserve_memory_arch(phys_addr_t base,
 					phys_addr_t size, bool nomap)
 {
-	if (nomap)
+	if (nomap) {
+		/*
+		 * If the memory is already reserved (by another region), we
+		 * should not allow it to be marked nomap.
+		 */
+		if (memblock_is_region_reserved(base, size))
+			return -EBUSY;
+
 		return memblock_mark_nomap(base, size);
+	}
 	return memblock_reserve(base, size);
 }