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smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sk.com; spf=pass smtp.mailfrom=sk.com; arc=none smtp.client-ip=166.125.252.92 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=sk.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sk.com X-AuditID: a67dfc5b-669ff7000002311f-cc-68789fb3a763 From: Byungchul Park To: willy@infradead.org, netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, kernel_team@skhynix.com, almasrymina@google.com, ilias.apalodimas@linaro.org, harry.yoo@oracle.com, akpm@linux-foundation.org, andrew+netdev@lunn.ch, asml.silence@gmail.com, toke@redhat.com, david@redhat.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, linux-rdma@vger.kernel.org, bpf@vger.kernel.org, vishal.moola@gmail.com, hannes@cmpxchg.org, ziy@nvidia.com, jackmanb@google.com, wei.fang@nxp.com, shenwei.wang@nxp.com, xiaoning.wang@nxp.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, anthony.l.nguyen@intel.com, przemyslaw.kitszel@intel.com, sgoutham@marvell.com, gakula@marvell.com, sbhatta@marvell.com, hkelam@marvell.com, bbhushan2@marvell.com, tariqt@nvidia.com, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com, sdf@fomichev.me, saeedm@nvidia.com, leon@kernel.org, mbloch@nvidia.com, danishanwar@ti.com, rogerq@kernel.org, nbd@nbd.name, lorenzo@kernel.org, ryder.lee@mediatek.com, shayne.chen@mediatek.com, sean.wang@mediatek.com, matthias.bgg@gmail.com, angelogioacchino.delregno@collabora.com, aleksander.lobakin@intel.com, horms@kernel.org, m-malladi@ti.com, krzysztof.kozlowski@linaro.org, matthias.schiffer@ew.tq-group.com, robh@kernel.org, imx@lists.linux.dev, intel-wired-lan@lists.osuosl.org, linux-arm-kernel@lists.infradead.org, linux-wireless@vger.kernel.org, linux-mediatek@lists.infradead.org Subject: [PATCH net-next v11 01/12] netmem: introduce struct netmem_desc mirroring struct page Date: Thu, 17 Jul 2025 16:00:41 +0900 Message-Id: <20250717070052.6358-2-byungchul@sk.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20250717070052.6358-1-byungchul@sk.com> References: <20250717070052.6358-1-byungchul@sk.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-Brightmail-Tracker: H4sIAAAAAAAAA02Se2xTZRjG/c53bqurOVTUsxlDaJjTGZDp0BeDBg2JxyCJkf/AKI070kp3 sYPSGckGq5EtrCMwzNoV2MbYpSW0adlWRwd6NsYugqOMWdzWQdGBcfPCRm3pRj3rQuS/J+/7 /J7n+5KXxapjdDqry98pGvI1ejWtIBXTqQ0rvcdN2tV9wafA7jpFw5WZegqcURM03/BREGjl 4exQlAC7ox3BbGyUAU/5GIaZnos0nKiPYIi5K0mw/2Qm4Z7rPobfesMM9EnzJDg9m2CiaZIE /zcdGLrvZUC4qo+GSnMcgzX0NQ2JX+IUdMX+ZGCfr4WArj/aGBhqt1BQff8kho7SG3LXrREK rnbaabhadgVB6FSCgklJLpxqGWPA4rQhkM630rDP/CpMtc0y8PeRHgwTlvXwoMYIvXVPQ2Rw CsHoyWsEJPw+Bi6HTlPQ4+ogYPhmDEPkwFEaKqarEFyzdhLw41E3BY2Dw4T8js0wkpgj4HCg joZb5gkEge4wCbV7LQhc54IU/OOXvxyP2un17wjdU39hwTfeiIQzrdcJ4c7BB4QQPDdACN/Z xhmhzrNL8LZkCSf8vxNCRTCABY+jnBY8dw8xwtiInxb6auKk4G0sEe54reiD57Yo1uWKep1R NLz81jaF9kx0Y2FPtmm+rBeVovLMCpTC8lwO39AeIh7qyMAcXtA0l8kHg7GkXspl8zPhi2QF UrCYu5TKd3lrksCT3Md8lXSWXtAkl8HvvWxPzpVykOVfM1oMXcY73d8ng1K4NXy8+lDSr5I9 ww2lzKJ/Cd9v/VUuYOWCTN51TLUwxjJa1laLF2PCKXxrxxeLOo3/oSVIHkSc7RHa9j9te4Su Q9iBVLp8Y55Gp89ZpS3O15lWfVqQ50Hy1TbtmdvqQ3eHNkuIY5E6VbnNvVurojTGouI8CfEs Vi9VHg4YtSplrqb4S9FQ8Ilhl14sktCzLKl+RvlKZHeuituu2SnuEMVC0fBwS7Ap6aUo7Yl3 Vzudsef7q8kS/MalQse30psXhpcPNrw4vuEr8vGoZ02l3jTrqHkNr7geqjpQ8t7PBS9kbOjH 7fyO/ZqP3NTrm+azmPmRznUDL23JSd+6PLDss+bi7V7rUH3T+3uk5pWBx9In3/6w7Hba7SOJ 0fNrb66t5j6XLuSuqJ2e2ejYr2lSk0VaTXYWNhRp/gM+u27hsQMAAA== X-Brightmail-Tracker: H4sIAAAAAAAAA02SbWxTdRTG87//+7aGmlon3kxFUoUlmAHNXHKii5Is6g1EY/SDiSa6xl1t 3VawHbUzUTt2jW6Bbg5MttLhxjbYVrSlZVuFMuS2aQsThO4lVcaG3SQTh4AdtaVl827EyLfn nPM7z3M+HBarc1QBazDWCCajrkpDK0jFq8/VF3m/teo357pKwek+QsPFZCcFrrQVDl/xUxDr 4+DEhTQBzv5BBAuZSwx4GyYxJEMRGro6Uxgynj0kOH8WSbjtvoPh93CCgah0lwSX9xWYPnSV hMCXQxiCt9dBoilKwx4xi6Ft6gsaln7NUnAy8xcDu/y9BATbz8jlnwMMXBi0U7DvTg+GIdsV OXBmgoLR404aRusvIpg6skTBVUlOne+dZMDuciCQTvXRsEsshvmBBQZufhPCMG3fAoutFgh3 rIbUyDyCSz3jBCwF/Aycn/qegpB7iICx3zIYUrvbaWi83oRgvO04AT+1eyjoHhkj5DvegIml HAF7Yx00zIjTCGLBBAn76+wI3MNxCm4FRHJLGR+cv4F5/+VuxB/r+4Xg55oXCT4+fJbgf3Bc ZvgO707e17uB7wr8QfCN8Rjmvf0NNO/9u4XhJycCNB9tzZK8r/tzfs7Xhl5b85aitEKoMlgE 06bnyxX6Y+ltO0Ja6936MLKhhsJGlMdyqme41NkcXta0qpCLxzMrOl+l5ZKJCNmIFCxWnVvF nfS1EsuDh1TvcE3SCXpZk6p1XN1550pfKRvZ/xHRPdMnOJfnxxWjPFUJl93XssKrZWbsoI25 xz/InWmblQNYOaCQcx9QL7exvFo/sB83I6XjPsrxP+W4j+pAuB/lG4yWap2hqmSjuVJfazRY N763vdqL5J889Gnuaz9aGH1ZQioWaVYpyz0f69WUzmKurZYQx2JNvnJvzKJXKyt0tZ8Ipu3v mnZWCWYJPcqSmkeUW98UytWqD3Q1QqUg7BBM/00JNq/Ahh54f30dWWMxxQ+WD45UjHueSicX r5VEHtv2Yry46LuWoGv8q2Rdj/bhA1n21mfDBWW2w83Z2bA0dWp1RJzzrO156XXUfvN0dfHa qC/k/SgVVh/d9OHmzq2VTet3v7BGJK1PnhNbEtcS6ev201Ft0czb6htPlymNjsefncs/OhuR SjWkWa/TbsAms+5fo9b3GY8DAAA= X-CFilter-Loop: Reflected To simplify struct page, the page pool members of struct page should be moved to other, allowing these members to be removed from struct page. Introduce a network memory descriptor to store the members, struct netmem_desc, and make it union'ed with the existing fields in struct net_iov, allowing to organize the fields of struct net_iov. Signed-off-by: Byungchul Park Reviewed-by: Toke H=C3=B8iland-J=C3=B8rgensen Reviewed-by: Pavel Begunkov Reviewed-by: Mina Almasry Reviewed-by: Vlastimil Babka Acked-by: Harry Yoo --- include/net/netmem.h | 116 +++++++++++++++++++++++++++++++++++-------- 1 file changed, 95 insertions(+), 21 deletions(-) diff --git a/include/net/netmem.h b/include/net/netmem.h index de1d95f04076..535cf17b9134 100644 --- a/include/net/netmem.h +++ b/include/net/netmem.h @@ -12,6 +12,50 @@ #include #include =20 +/* These fields in struct page are used by the page_pool and net stack: + * + * struct { + * unsigned long pp_magic; + * struct page_pool *pp; + * unsigned long _pp_mapping_pad; + * unsigned long dma_addr; + * atomic_long_t pp_ref_count; + * }; + * + * We mirror the page_pool fields here so the page_pool can access these + * fields without worrying whether the underlying fields belong to a + * page or netmem_desc. + * + * CAUTION: Do not update the fields in netmem_desc without also + * updating the anonymous aliasing union in struct net_iov. + */ +struct netmem_desc { + unsigned long _flags; + unsigned long pp_magic; + struct page_pool *pp; + unsigned long _pp_mapping_pad; + unsigned long dma_addr; + atomic_long_t pp_ref_count; +}; + +#define NETMEM_DESC_ASSERT_OFFSET(pg, desc) \ + static_assert(offsetof(struct page, pg) =3D=3D \ + offsetof(struct netmem_desc, desc)) +NETMEM_DESC_ASSERT_OFFSET(flags, _flags); +NETMEM_DESC_ASSERT_OFFSET(pp_magic, pp_magic); +NETMEM_DESC_ASSERT_OFFSET(pp, pp); +NETMEM_DESC_ASSERT_OFFSET(_pp_mapping_pad, _pp_mapping_pad); +NETMEM_DESC_ASSERT_OFFSET(dma_addr, dma_addr); +NETMEM_DESC_ASSERT_OFFSET(pp_ref_count, pp_ref_count); +#undef NETMEM_DESC_ASSERT_OFFSET + +/* + * Since struct netmem_desc uses the space in struct page, the size + * should be checked, until struct netmem_desc has its own instance from + * slab, to avoid conflicting with other members within struct page. + */ +static_assert(sizeof(struct netmem_desc) <=3D offsetof(struct page, _refco= unt)); + /* net_iov */ =20 DECLARE_STATIC_KEY_FALSE(page_pool_mem_providers); @@ -30,13 +74,48 @@ enum net_iov_type { NET_IOV_MAX =3D ULONG_MAX }; =20 +/* A memory descriptor representing abstract networking I/O vectors, + * generally for non-pages memory that doesn't have its corresponding + * struct page and needs to be explicitly allocated through slab. + * + * net_iovs are allocated and used by networking code, and the size of + * the chunk is PAGE_SIZE. + * + * This memory can be any form of non-struct paged memory. Examples + * include imported dmabuf memory and imported io_uring memory. See + * net_iov_type for all the supported types. + * + * @pp_magic: pp field, similar to the one in struct page/struct + * netmem_desc. + * @pp: the pp this net_iov belongs to, if any. + * @dma_addr: the dma addrs of the net_iov. Needed for the network + * card to send/receive this net_iov. + * @pp_ref_count: the pp ref count of this net_iov, exactly the same + * usage as struct page/struct netmem_desc. + * @owner: the net_iov_area this net_iov belongs to, if any. + * @type: the type of the memory. Different types of net_iovs are + * supported. + */ struct net_iov { - enum net_iov_type type; - unsigned long pp_magic; - struct page_pool *pp; + union { + struct netmem_desc desc; + + /* XXX: The following part should be removed once all + * the references to them are converted so as to be + * accessed via netmem_desc e.g. niov->desc.pp instead + * of niov->pp. + */ + struct { + unsigned long _flags; + unsigned long pp_magic; + struct page_pool *pp; + unsigned long _pp_mapping_pad; + unsigned long dma_addr; + atomic_long_t pp_ref_count; + }; + }; struct net_iov_area *owner; - unsigned long dma_addr; - atomic_long_t pp_ref_count; + enum net_iov_type type; }; =20 struct net_iov_area { @@ -48,27 +127,22 @@ struct net_iov_area { unsigned long base_virtual; }; =20 -/* These fields in struct page are used by the page_pool and net stack: +/* net_iov is union'ed with struct netmem_desc mirroring struct page, so + * the page_pool can access these fields without worrying whether the + * underlying fields are accessed via netmem_desc or directly via + * net_iov, until all the references to them are converted so as to be + * accessed via netmem_desc e.g. niov->desc.pp instead of niov->pp. * - * struct { - * unsigned long pp_magic; - * struct page_pool *pp; - * unsigned long _pp_mapping_pad; - * unsigned long dma_addr; - * atomic_long_t pp_ref_count; - * }; - * - * We mirror the page_pool fields here so the page_pool can access these f= ields - * without worrying whether the underlying fields belong to a page or net_= iov. - * - * The non-net stack fields of struct page are private to the mm stack and= must - * never be mirrored to net_iov. + * The non-net stack fields of struct page are private to the mm stack + * and must never be mirrored to net_iov. */ -#define NET_IOV_ASSERT_OFFSET(pg, iov) \ - static_assert(offsetof(struct page, pg) =3D=3D \ +#define NET_IOV_ASSERT_OFFSET(desc, iov) \ + static_assert(offsetof(struct netmem_desc, desc) =3D=3D \ offsetof(struct net_iov, iov)) +NET_IOV_ASSERT_OFFSET(_flags, _flags); NET_IOV_ASSERT_OFFSET(pp_magic, pp_magic); NET_IOV_ASSERT_OFFSET(pp, pp); +NET_IOV_ASSERT_OFFSET(_pp_mapping_pad, _pp_mapping_pad); NET_IOV_ASSERT_OFFSET(dma_addr, dma_addr); NET_IOV_ASSERT_OFFSET(pp_ref_count, pp_ref_count); #undef NET_IOV_ASSERT_OFFSET --=20 2.17.1