diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c
index 71d34186dec9..f38d36fbeef3 100644
--- a/drivers/scsi/sg.c
+++ b/drivers/scsi/sg.c
@@ -1623,10 +1623,35 @@ sg_remove_device(struct device *cl_dev)
 }
 
 module_param_named(scatter_elem_sz, scatter_elem_sz, int, S_IRUGO | S_IWUSR);
-module_param_named(def_reserved_size, def_reserved_size, int,
-		   S_IRUGO | S_IWUSR);
 module_param_named(allow_dio, sg_allow_dio, int, S_IRUGO | S_IWUSR);
 
+static int def_reserved_size_set(const char *val, const struct kernel_param *kp)
+{
+	int size, ret;
+
+	if (!val)
+		return -EINVAL;
+
+	ret = kstrtoint(val, 0, &size);
+	if (ret)
+		return ret;
+
+	/* limit to 1 MB */
+	if (size < 0 || size > 1048576)
+		return -ERANGE;
+
+	def_reserved_size = size;
+	return 0;
+}
+
+static const struct kernel_param_ops def_reserved_size_ops = {
+	.set	= def_reserved_size_set,
+	.get	= param_get_int,
+};
+
+module_param_cb(def_reserved_size, &def_reserved_size_ops, &def_reserved_size,
+		   S_IRUGO | S_IWUSR);
+
 MODULE_AUTHOR("Douglas Gilbert");
 MODULE_DESCRIPTION("SCSI generic (sg) driver");
 MODULE_LICENSE("GPL");