--- x/drivers/media/dvb-core/dvbdev.c
+++ y/drivers/media/dvb-core/dvbdev.c
@@ -109,8 +109,10 @@ static int dvb_device_open(struct inode
 			err = file->f_op->open(inode, file);
 		up_read(&minor_rwsem);
 		mutex_unlock(&dvbdev_mutex);
-		if (err)
+		if (err) {
+			WARN(1, "open %pS\n", file->f_op->open);
 			dvb_device_put(dvbdev);
+		}
 		return err;
 	}
 fail: