net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag

When rx_flag == MTK_RX_FLAGS_HWLRO,
rx_data_len = MTK_MAX_LRO_RX_LENGTH(4096 * 3) > PAGE_SIZE.
netdev_alloc_frag is for alloction of page fragment only.
Reference to other drivers and Documentation/vm/page_frags.rst

Branch to use __get_free_pages when ring->frag_size > PAGE_SIZE.
Signed-off-by: Chen Lin <chen45464546@163.com>
Link: https://lore.kernel.org/r/1654692413-2598-1-git-send-email-chen45464546@163.comSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/mediatek/mtk_eth_soc.c

@@ -899,6 +899,17 @@ static bool mtk_rx_get_desc(struct mtk_eth *eth, struct mtk_rx_dma_v2 *rxd,
 	return true;
 }
 
+static void *mtk_max_lro_buf_alloc(gfp_t gfp_mask)
+{
+	unsigned int size = mtk_max_frag_size(MTK_MAX_LRO_RX_LENGTH);
+	unsigned long data;
+
+	data = __get_free_pages(gfp_mask | __GFP_COMP | __GFP_NOWARN,
+				get_order(size));
+
+	return (void *)data;
+}
+
 /* the qdma core needs scratch memory to be setup */
 static int mtk_init_fq_dma(struct mtk_eth *eth)
 {
@@ -1467,7 +1478,10 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
 			goto release_desc;
 
 		/* alloc new buffer */
-		new_data = napi_alloc_frag(ring->frag_size);
+		if (ring->frag_size <= PAGE_SIZE)
+			new_data = napi_alloc_frag(ring->frag_size);
+		else
+			new_data = mtk_max_lro_buf_alloc(GFP_ATOMIC);
 		if (unlikely(!new_data)) {
 			netdev->stats.rx_dropped++;
 			goto release_desc;
@@ -1914,7 +1928,10 @@ static int mtk_rx_alloc(struct mtk_eth *eth, int ring_no, int rx_flag)
 		return -ENOMEM;
 
 	for (i = 0; i < rx_dma_size; i++) {
-		ring->data[i] = netdev_alloc_frag(ring->frag_size);
+		if (ring->frag_size <= PAGE_SIZE)
+			ring->data[i] = netdev_alloc_frag(ring->frag_size);
+		else
+			ring->data[i] = mtk_max_lro_buf_alloc(GFP_KERNEL);
 		if (!ring->data[i])
 			return -ENOMEM;
 	}