diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index f675a3bb2c88..fcd728d7cf72 100644
--- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -336,7 +336,12 @@ drm_setclientcap(struct drm_device *dev, void *data, struct drm_file *file_priv)
 	case DRM_CLIENT_CAP_ATOMIC:
 		if (!drm_core_check_feature(dev, DRIVER_ATOMIC))
 			return -EOPNOTSUPP;
-		if (req->value > 1)
+		/* The modesetting DDX has a totally broken idea of atomic. */
+		if (current->comm[0] == 'X' && req->value == 1) {
+			pr_info("broken atomic modeset userspace detected, disabling atomic\n");
+			return -EOPNOTSUPP;
+		}
+		if (req->value > 2)
 			return -EINVAL;
 		file_priv->atomic = req->value;
 		file_priv->universal_planes = req->value;