Patch "net/mlx4_en: Schedule napi when RX buffers allocation fails" has been added to the 4.0-stable tree

@@ -1467,6 +1467,7 @@ static void mlx4_en_service_task(struct
 		if (mdev->dev->caps.flags2 & MLX4_DEV_CAP_FLAG2_TS)
 			mlx4_en_ptp_overflow_check(mdev);
 
+		mlx4_en_recover_from_oom(priv);
 		queue_delayed_work(mdev->workqueue, &priv->service_task,
 				   SERVICE_TASK_DELAY);
 	}

@@ -244,6 +244,12 @@ static int mlx4_en_prepare_rx_desc(struc
 	return mlx4_en_alloc_frags(priv, rx_desc, frags, ring->page_alloc, gfp);
 }
 
+static inline bool mlx4_en_is_ring_empty(struct mlx4_en_rx_ring *ring)
+{
+	BUG_ON((u32)(ring->prod - ring->cons) > ring->actual_size);
+	return ring->prod == ring->cons;
+}
+
 static inline void mlx4_en_update_rx_prod_db(struct mlx4_en_rx_ring *ring)
 {
 	*ring->wqres.db.db = cpu_to_be32(ring->prod & 0xffff);

@@ -315,8 +321,7 @@ static void mlx4_en_free_rx_buf(struct m
 	       ring->cons, ring->prod);
 
 	/* Unmap and free Rx buffers */
-	BUG_ON((u32) (ring->prod - ring->cons) > ring->actual_size);
-	while (ring->cons != ring->prod) {
+	while (!mlx4_en_is_ring_empty(ring)) {
 		index = ring->cons & ring->size_mask;
 		en_dbg(DRV, priv, "Processing descriptor:%d\n", index);
 		mlx4_en_free_rx_desc(priv, ring, index);

@@ -491,6 +496,23 @@ err_allocator:
 	return err;
 }
 
+/* We recover from out of memory by scheduling our napi poll
+ * function (mlx4_en_process_cq), which tries to allocate
+ * all missing RX buffers (call to mlx4_en_refill_rx_buffers).
+ */
+void mlx4_en_recover_from_oom(struct mlx4_en_priv *priv)
+{
+	int ring;
+
+	if (!priv->port_up)
+		return;
+
+	for (ring = 0; ring < priv->rx_ring_num; ring++) {
+		if (mlx4_en_is_ring_empty(priv->rx_ring[ring]))
+			napi_reschedule(&priv->rx_cq[ring]->napi);
+	}
+}
+
 void mlx4_en_destroy_rx_ring(struct mlx4_en_priv *priv,
 			     struct mlx4_en_rx_ring **pring,
 			     u32 size, u16 stride)

@@ -790,6 +790,7 @@ int mlx4_en_activate_tx_ring(struct mlx4
 void mlx4_en_deactivate_tx_ring(struct mlx4_en_priv *priv,
 				struct mlx4_en_tx_ring *ring);
 void mlx4_en_set_num_rx_rings(struct mlx4_en_dev *mdev);
+void mlx4_en_recover_from_oom(struct mlx4_en_priv *priv);
 int mlx4_en_create_rx_ring(struct mlx4_en_priv *priv,
 			   struct mlx4_en_rx_ring **pring,
 			   u32 size, u16 stride, int node);