linux-kernel - Re: [PATCH net,v2] net: mana: Switch to page pool for jumbo frames

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Message-ID: <20250327050140.GA13258@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net>
Date: Wed, 26 Mar 2025 22:01:40 -0700
From: Shradha Gupta <shradhagupta@...ux.microsoft.com>
To: Haiyang Zhang <haiyangz@...rosoft.com>
Cc: linux-hyperv@...r.kernel.org, netdev@...r.kernel.org,
	decui@...rosoft.com, stephen@...workplumber.org, kys@...rosoft.com,
	paulros@...rosoft.com, olaf@...fle.de, vkuznets@...hat.com,
	davem@...emloft.net, wei.liu@...nel.org, edumazet@...gle.com,
	kuba@...nel.org, pabeni@...hat.com, leon@...nel.org,
	longli@...rosoft.com, ssengar@...ux.microsoft.com,
	linux-rdma@...r.kernel.org, daniel@...earbox.net,
	john.fastabend@...il.com, bpf@...r.kernel.org, ast@...nel.org,
	hawk@...nel.org, tglx@...utronix.de, jesse.brandeburg@...el.com,
	andrew+netdev@...n.ch, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH net,v2] net: mana: Switch to page pool for jumbo frames

On Tue, Mar 25, 2025 at 09:32:37AM -0700, Haiyang Zhang wrote:
> Frag allocators, such as netdev_alloc_frag(), were not designed to
> work for fragsz > PAGE_SIZE.
> 
> So, switch to page pool for jumbo frames instead of using page frag
> allocators. This driver is using page pool for smaller MTUs already.
> 
> Cc: stable@...r.kernel.org
> Fixes: 80f6215b450e ("net: mana: Add support for jumbo frame")
> Signed-off-by: Haiyang Zhang <haiyangz@...rosoft.com>
> ---
> v2: updated the commit msg as suggested by Jakub Kicinski.
> 
> ---
>  drivers/net/ethernet/microsoft/mana/mana_en.c | 46 ++++---------------
>  1 file changed, 9 insertions(+), 37 deletions(-)
> 
> diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
> index 9a8171f099b6..4d41f4cca3d8 100644
> --- a/drivers/net/ethernet/microsoft/mana/mana_en.c
> +++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
> @@ -661,30 +661,16 @@ int mana_pre_alloc_rxbufs(struct mana_port_context *mpc, int new_mtu, int num_qu
>  	mpc->rxbpre_total = 0;
>  
>  	for (i = 0; i < num_rxb; i++) {
> -		if (mpc->rxbpre_alloc_size > PAGE_SIZE) {
> -			va = netdev_alloc_frag(mpc->rxbpre_alloc_size);
> -			if (!va)
> -				goto error;
> -
> -			page = virt_to_head_page(va);
> -			/* Check if the frag falls back to single page */
> -			if (compound_order(page) <
> -			    get_order(mpc->rxbpre_alloc_size)) {
> -				put_page(page);
> -				goto error;
> -			}
> -		} else {
> -			page = dev_alloc_page();
> -			if (!page)
> -				goto error;
> +		page = dev_alloc_pages(get_order(mpc->rxbpre_alloc_size));
> +		if (!page)
> +			goto error;
>  
> -			va = page_to_virt(page);
> -		}
> +		va = page_to_virt(page);
>  
>  		da = dma_map_single(dev, va + mpc->rxbpre_headroom,
>  				    mpc->rxbpre_datasize, DMA_FROM_DEVICE);
>  		if (dma_mapping_error(dev, da)) {
> -			put_page(virt_to_head_page(va));
> +			put_page(page);
>  			goto error;
>  		}
>  
> @@ -1672,7 +1658,7 @@ static void mana_rx_skb(void *buf_va, bool from_pool,
>  }
>  
>  static void *mana_get_rxfrag(struct mana_rxq *rxq, struct device *dev,
> -			     dma_addr_t *da, bool *from_pool, bool is_napi)
> +			     dma_addr_t *da, bool *from_pool)
>  {
>  	struct page *page;
>  	void *va;
> @@ -1683,21 +1669,6 @@ static void *mana_get_rxfrag(struct mana_rxq *rxq, struct device *dev,
>  	if (rxq->xdp_save_va) {
>  		va = rxq->xdp_save_va;
>  		rxq->xdp_save_va = NULL;
> -	} else if (rxq->alloc_size > PAGE_SIZE) {
> -		if (is_napi)
> -			va = napi_alloc_frag(rxq->alloc_size);
> -		else
> -			va = netdev_alloc_frag(rxq->alloc_size);
> -
> -		if (!va)
> -			return NULL;
> -
> -		page = virt_to_head_page(va);
> -		/* Check if the frag falls back to single page */
> -		if (compound_order(page) < get_order(rxq->alloc_size)) {
> -			put_page(page);
> -			return NULL;
> -		}
>  	} else {
>  		page = page_pool_dev_alloc_pages(rxq->page_pool);
>  		if (!page)
> @@ -1730,7 +1701,7 @@ static void mana_refill_rx_oob(struct device *dev, struct mana_rxq *rxq,
>  	dma_addr_t da;
>  	void *va;
>  
> -	va = mana_get_rxfrag(rxq, dev, &da, &from_pool, true);
> +	va = mana_get_rxfrag(rxq, dev, &da, &from_pool);
>  	if (!va)
>  		return;
>  
> @@ -2172,7 +2143,7 @@ static int mana_fill_rx_oob(struct mana_recv_buf_oob *rx_oob, u32 mem_key,
>  	if (mpc->rxbufs_pre)
>  		va = mana_get_rxbuf_pre(rxq, &da);
>  	else
> -		va = mana_get_rxfrag(rxq, dev, &da, &from_pool, false);
> +		va = mana_get_rxfrag(rxq, dev, &da, &from_pool);
>  
>  	if (!va)
>  		return -ENOMEM;
> @@ -2258,6 +2229,7 @@ static int mana_create_page_pool(struct mana_rxq *rxq, struct gdma_context *gc)
>  	pprm.nid = gc->numa_node;
>  	pprm.napi = &rxq->rx_cq.napi;
>  	pprm.netdev = rxq->ndev;
> +	pprm.order = get_order(rxq->alloc_size);
>  
>  	rxq->page_pool = page_pool_create(&pprm);
>  
> -- 
Reviewed-by: Shradha Gupta <shradhagupta@...ux.microsoft.com>
> 2.34.1