From nobody Thu Nov 14 16:55:26 2024 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0D821EB64D9 for ; Thu, 29 Jun 2023 12:06:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229540AbjF2MGO (ORCPT ); Thu, 29 Jun 2023 08:06:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47260 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232346AbjF2MFw (ORCPT ); Thu, 29 Jun 2023 08:05:52 -0400 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 770383C18; Thu, 29 Jun 2023 05:05:20 -0700 (PDT) Received: from dggpemm500005.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4QsHB22YCZzqVVJ; Thu, 29 Jun 2023 20:02:02 +0800 (CST) Received: from localhost.localdomain (10.69.192.56) by dggpemm500005.china.huawei.com (7.185.36.74) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.27; Thu, 29 Jun 2023 20:04:47 +0800 From: Yunsheng Lin To: , , CC: , , Yunsheng Lin , Lorenzo Bianconi , Alexander Duyck , Liang Chen , Alexander Lobakin , Saeed Mahameed , Leon Romanovsky , Eric Dumazet , Jesper Dangaard Brouer , Ilias Apalodimas , Subject: [PATCH v5 RFC 1/6] page_pool: frag API support for 32-bit arch with 64-bit DMA Date: Thu, 29 Jun 2023 20:02:21 +0800 Message-ID: <20230629120226.14854-2-linyunsheng@huawei.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20230629120226.14854-1-linyunsheng@huawei.com> References: <20230629120226.14854-1-linyunsheng@huawei.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.69.192.56] X-ClientProxiedBy: dggems702-chm.china.huawei.com (10.3.19.179) To dggpemm500005.china.huawei.com (7.185.36.74) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Currently page_pool_alloc_frag() is not supported in 32-bit arch with 64-bit DMA because of the overlap issue between pp_frag_count and dma_addr_upper in 'struct page' for those arches, which seems to be quite common, see [1], which means driver may need to handle it when using frag API. In order to simplify the driver's work when using frag API this patch allows page_pool_alloc_frag() to call page_pool_alloc_pages() to return pages for those arches. mlx5 calls page_pool_create() with PP_FLAG_PAGE_FRAG and is not using the frag API, and the PP_FLAG_PAGE_FRAG checking will now be removed in this patch, a new checking for the mlx5 driver is needed to retain the old behavior. As we have not come up with a better name yet, so PAGE_POOL_DMA_USE_PP_FRAG_COUNT is reused here. Note that it may aggravate truesize underestimate problem for skb as there is no page splitting for those pages, if driver need a accurate truesize, it may calculate that according to frag size, page order and PAGE_POOL_DMA_USE_PP_FRAG_COUNT being true or not. And we may provide a helper for that if it turns out to be helpful. 1. https://lore.kernel.org/all/20211117075652.58299-1-linyunsheng@huawei.co= m/ Signed-off-by: Yunsheng Lin CC: Lorenzo Bianconi CC: Alexander Duyck CC: Liang Chen CC: Alexander Lobakin --- .../net/ethernet/mellanox/mlx5/core/en_main.c | 10 +++++ include/net/page_pool.h | 45 ++++++++++++++++--- net/core/page_pool.c | 18 ++------ 3 files changed, 52 insertions(+), 21 deletions(-) diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/ne= t/ethernet/mellanox/mlx5/core/en_main.c index a7c526ee5024..42ccb77a1b6c 100644 --- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c @@ -832,6 +832,16 @@ static int mlx5e_alloc_rq(struct mlx5e_params *params, /* Create a page_pool and register it with rxq */ struct page_pool_params pp_params =3D { 0 }; =20 + /* Return error here to avoid mlx5e_page_release_fragmented() + * calling page_pool_defrag_page() to write to pp_frag_count + * which is overlapped with dma_addr_upper in 'struct page' for + * arch with PAGE_POOL_DMA_USE_PP_FRAG_COUNT being true. + */ + if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT) { + err =3D -EINVAL; + goto err_free_by_rq_type; + } + pp_params.order =3D 0; pp_params.flags =3D PP_FLAG_DMA_MAP | PP_FLAG_DMA_SYNC_DEV | PP_FLAG= _PAGE_FRAG; pp_params.pool_size =3D pool_size; diff --git a/include/net/page_pool.h b/include/net/page_pool.h index 126f9e294389..83bd13491105 100644 --- a/include/net/page_pool.h +++ b/include/net/page_pool.h @@ -32,7 +32,7 @@ =20 #include /* Needed by ptr_ring */ #include -#include +#include =20 #define PP_FLAG_DMA_MAP BIT(0) /* Should page_pool do the DMA * map/unmap @@ -50,6 +50,9 @@ PP_FLAG_DMA_SYNC_DEV |\ PP_FLAG_PAGE_FRAG) =20 +#define PAGE_POOL_DMA_USE_PP_FRAG_COUNT \ + (sizeof(dma_addr_t) > sizeof(unsigned long)) + /* * Fast allocation side cache array/stack * @@ -219,8 +222,33 @@ static inline struct page *page_pool_dev_alloc_pages(s= truct page_pool *pool) return page_pool_alloc_pages(pool, gfp); } =20 -struct page *page_pool_alloc_frag(struct page_pool *pool, unsigned int *of= fset, - unsigned int size, gfp_t gfp); +struct page *__page_pool_alloc_frag(struct page_pool *pool, + unsigned int *offset, unsigned int size, + gfp_t gfp); + +static inline struct page *page_pool_alloc_frag(struct page_pool *pool, + unsigned int *offset, + unsigned int size, gfp_t gfp) +{ + unsigned int max_size =3D PAGE_SIZE << pool->p.order; + + size =3D ALIGN(size, dma_get_cache_alignment()); + + if (WARN_ON(!(pool->p.flags & PP_FLAG_PAGE_FRAG) || + size > max_size)) + return NULL; + + /* Don't allow page splitting and allocate one big frag + * for 32-bit arch with 64-bit DMA, corresponding to + * the checking in page_pool_is_last_frag(). + */ + if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT) { + *offset =3D 0; + return page_pool_alloc_pages(pool, gfp); + } + + return __page_pool_alloc_frag(pool, offset, size, gfp); +} =20 static inline struct page *page_pool_dev_alloc_frag(struct page_pool *pool, unsigned int *offset, @@ -322,8 +350,14 @@ static inline long page_pool_defrag_page(struct page *= page, long nr) static inline bool page_pool_is_last_frag(struct page_pool *pool, struct page *page) { - /* If fragments aren't enabled or count is 0 we were the last user */ + /* We assume we are the last frag user that is still holding + * on to the page if: + * 1. Fragments aren't enabled. + * 2. We are running in 32-bit arch with 64-bit DMA. + * 3. page_pool_defrag_page() indicate we are the last user. + */ return !(pool->p.flags & PP_FLAG_PAGE_FRAG) || + PAGE_POOL_DMA_USE_PP_FRAG_COUNT || (page_pool_defrag_page(page, 1) =3D=3D 0); } =20 @@ -357,9 +391,6 @@ static inline void page_pool_recycle_direct(struct page= _pool *pool, page_pool_put_full_page(pool, page, true); } =20 -#define PAGE_POOL_DMA_USE_PP_FRAG_COUNT \ - (sizeof(dma_addr_t) > sizeof(unsigned long)) - static inline dma_addr_t page_pool_get_dma_addr(struct page *page) { dma_addr_t ret =3D page->dma_addr; diff --git a/net/core/page_pool.c b/net/core/page_pool.c index a3e12a61d456..9c4118c62997 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -14,7 +14,6 @@ #include =20 #include -#include #include #include /* for put_page() */ #include @@ -200,10 +199,6 @@ static int page_pool_init(struct page_pool *pool, */ } =20 - if (PAGE_POOL_DMA_USE_PP_FRAG_COUNT && - pool->p.flags & PP_FLAG_PAGE_FRAG) - return -EINVAL; - #ifdef CONFIG_PAGE_POOL_STATS pool->recycle_stats =3D alloc_percpu(struct page_pool_recycle_stats); if (!pool->recycle_stats) @@ -715,18 +710,13 @@ static void page_pool_free_frag(struct page_pool *poo= l) page_pool_return_page(pool, page); } =20 -struct page *page_pool_alloc_frag(struct page_pool *pool, - unsigned int *offset, - unsigned int size, gfp_t gfp) +struct page *__page_pool_alloc_frag(struct page_pool *pool, + unsigned int *offset, + unsigned int size, gfp_t gfp) { unsigned int max_size =3D PAGE_SIZE << pool->p.order; struct page *page =3D pool->frag_page; =20 - if (WARN_ON(!(pool->p.flags & PP_FLAG_PAGE_FRAG) || - size > max_size)) - return NULL; - - size =3D ALIGN(size, dma_get_cache_alignment()); *offset =3D pool->frag_offset; =20 if (page && *offset + size > max_size) { @@ -759,7 +749,7 @@ struct page *page_pool_alloc_frag(struct page_pool *poo= l, alloc_stat_inc(pool, fast); return page; } -EXPORT_SYMBOL(page_pool_alloc_frag); +EXPORT_SYMBOL(__page_pool_alloc_frag); =20 static void page_pool_empty_ring(struct page_pool *pool) { --=20 2.33.0