From 0c285bd081da55bd63da18f7596e7107a46bb798 Mon Sep 17 00:00:00 2001 From: Felix Fietkau Date: Thu, 12 Jul 2018 17:19:07 +0200 Subject: [PATCH] ramips: ethernet: use own page_frag_cache Using the NAPI or netdev frag cache along with other drivers can lead to 32 KiB pages being held for a long time, despite only being used for very few page fragment. This can happen if the ethernet driver grabs one or two fragments for rx ring refill, while other drivers use (and free up) the remaining fragments. The 32 KiB higher-order page can only be freed once all users have freed their fragments, which only happens after the rings of all drivers holding the fragments have wrapped around. Depending on the traffic patterns, this can waste a lot of memory and look a lot like a memory leak Signed-off-by: Felix Fietkau --- .../drivers/net/ethernet/mediatek/mtk_eth_soc.c | 17 ++++++++++++++--- .../drivers/net/ethernet/mediatek/mtk_eth_soc.h | 1 + 2 files changed, 15 insertions(+), 3 deletions(-) diff --git a/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.c index 8dcc17774b..8bf17f629c 100644 --- a/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.c +++ b/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.c @@ -219,8 +219,9 @@ static inline void fe_set_txd(struct fe_tx_dma *txd, struct fe_tx_dma *dma_txd) static void fe_clean_rx(struct fe_priv *priv) { - int i; struct fe_rx_ring *ring = &priv->rx_ring; + struct page *page; + int i; if (ring->rx_data) { for (i = 0; i < ring->rx_ring_size; i++) @@ -244,6 +245,13 @@ static void fe_clean_rx(struct fe_priv *priv) ring->rx_phys); ring->rx_dma = NULL; } + + if (!ring->frag_cache.va) + return; + + page = virt_to_page(ring->frag_cache.va); + __page_frag_cache_drain(page, ring->frag_cache.pagecnt_bias); + memset(&ring->frag_cache, 0, sizeof(ring->frag_cache)); } static int fe_alloc_rx(struct fe_priv *priv) @@ -258,7 +266,9 @@ static int fe_alloc_rx(struct fe_priv *priv) goto no_rx_mem; for (i = 0; i < ring->rx_ring_size; i++) { - ring->rx_data[i] = netdev_alloc_frag(ring->frag_size); + ring->rx_data[i] = page_frag_alloc(&ring->frag_cache, + ring->frag_size, + GFP_KERNEL); if (!ring->rx_data[i]) goto no_rx_mem; } @@ -881,7 +891,8 @@ static int fe_poll_rx(struct napi_struct *napi, int budget, break; /* alloc new buffer */ - new_data = netdev_alloc_frag(ring->frag_size); + new_data = page_frag_alloc(&ring->frag_cache, ring->frag_size, + GFP_ATOMIC); if (unlikely(!new_data)) { stats->rx_dropped++; goto release_desc; diff --git a/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.h b/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.h index 517d8ba4dc..c42126116f 100644 --- a/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.h +++ b/target/linux/ramips/files-4.14/drivers/net/ethernet/mediatek/mtk_eth_soc.h @@ -454,6 +454,7 @@ struct fe_tx_ring { }; struct fe_rx_ring { + struct page_frag_cache frag_cache; struct fe_rx_dma *rx_dma; u8 **rx_data; dma_addr_t rx_phys; -- 2.30.2