diff --git a/drivers/tty/serial/qcom_geni_serial.c b/drivers/tty/serial/qcom_geni_serial.c
index 8058b839b26ce..cbb4f3222116a 100644
--- a/drivers/tty/serial/qcom_geni_serial.c
+++ b/drivers/tty/serial/qcom_geni_serial.c
@@ -1022,8 +1022,20 @@ static void qcom_geni_serial_handle_tx_dma(struct uart_port *uport)
 {
 	struct qcom_geni_serial_port *port = to_dev_port(uport);
 	struct tty_port *tport = &uport->state->port;
+	unsigned int fifo_len = kfifo_len(&tport->xmit_fifo);
+
+	/*
+	 * Only advance the kfifo if it still contains the bytes that were
+	 * transferred. uart_flush_buffer() may have run before this IRQ
+	 * fired: it calls kfifo_reset() under the port lock, making
+	 * fifo_len = 0 while tx_remaining remains non-zero. Calling
+	 * uart_xmit_advance() in that case would underflow kfifo->out past
+	 * kfifo->in, making kfifo_len() wrap to UART_XMIT_SIZE - tx_remaining
+	 * and triggering a spurious large DMA transfer of stale data.
+	 */
+	if (fifo_len >= port->tx_remaining)
+		uart_xmit_advance(uport, port->tx_remaining);
 
-	uart_xmit_advance(uport, port->tx_remaining);
 	geni_se_tx_dma_unprep(&port->se, port->tx_dma_addr, port->tx_remaining);
 	port->tx_dma_addr = 0;
 	port->tx_remaining = 0;