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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-681ff7000002311f-fa-6874f1796cc2 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 v10 01/12] netmem: introduce struct netmem_desc mirroring struct page Date: Mon, 14 Jul 2025 21:00:36 +0900 Message-Id: <20250714120047.35901-2-byungchul@sk.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20250714120047.35901-1-byungchul@sk.com> References: <20250714120047.35901-1-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: H4sIAAAAAAAAA01Se0xTdxTO7/7uq6Vd7qrbrsxlSRdj4qaTieYsYca4LLnTLdlkcdmWbDZy RxsB3W1hdNkyBiwL3UT2YINSWFFwhRpLWoGKBbE0gKADUbo75SFlEkUEFCUtVbtWZ+Z/X77z Pc5JDos1NXQya8gxiVKOLktLK0nlDdXBteabJv16p3Mt2FxHaDi3UEuBM5wPf1z2UjDUwMOJ wTABtsYWBLcjlxhwl4xgWAj00HCodhFDpGk/CbaBYhLuuJYwXOkOMdDrv0eC0/02jB+eIsH3 XSuGrjurIHSgl4b9xVEMlWPf0hC7GKWgPTLLQKHXQUD79WYGBltKKfhlqR5Da8HleNdkkILz bTYazhedQzB2JEbBlD9eOOMYYaDUaUXgP9lAQ2HxBphpvs3AfHkAw3jpFrhfkQfd9qdhsX8G waX6YQJiPi8Df44dpSDgaiXgwkQEw+IP1TRYbhxAMFzZRsCZ6iYK6vovEPE90iEYu0vAz0N2 GiaLxxEMdYVIqPqmFIGrQ6bgpi9+cjRso7dsFbpm5rDgHa1DwrGGvwnhatl9QpA7+gjhuHWU EezuXMHjWCMc8l0jBIs8hAV3YwktuG/9xAgjQR8t9FZEScFT97Vw1VOJ3nnuQ2VahphlyBOl lzfvUuqPhbfvC6Tk3yvqRgWoZLUFKVieS+XLf5ygH+Ez0wM4gWluNS/LkQd4OZfCL4R6SAtS spg7q+LbPRVEYrCM+5g/G+1EFsSyJLeKXwq8maDV3EZeDldRDzOf551NnQ9yFNwm/vfqCZTA mrimw1KHH+qf5E9X/kMmYnC811WjSdA4bi1qrsKJWp6bUvAX5ZP/Za7gTzlksgxx1sfs1v/t 1sfsdoQbkcaQk5etM2SlrtObcwz563bvzXaj+Nce/uruR150azDdjzgWaVVqmDbpNZQuz2jO 9iOexdrl6ulRSa9RZ+jMX4jS3k+k3CzR6EfPsqT2GfUri59naLhMnUncI4r7ROnRlGAVyQVo 5e7MJLXfrTr6qir91/oVns0bJvq2GQsdS7M1ytxtA/O5aXPzO4Nffm8tqTK+Z5rr7m97sawv /7Vdn70rvbRxh/56puKtnYZrK7cvk1rs+vGnylPfrwjVIvn1yFRDUsHkC0WnZ6+YQ59iTVLw DevB5N/S1pv8T7g7/8re1DO8NRZlPtCSRr0uZQ2WjLp/AY40DrWxAwAA X-Brightmail-Tracker: H4sIAAAAAAAAA02Se0yTZxTG937vd6Pa5LMg+4LJzJoZMowXNlnOss0Yl4x3F9mWmS1TN2nm l7WzXNZWAkuMaEsWGkC2uYQW2OoAx0UtaQWq1sJKhwg4ELSp46bVkQ5hjnGRUpW1mmX+95xz fud5zh+Hx4oIk8Rrsg2SLlulVbIyWpbxinFDwYxBvXlmYjVU2U+ycGX2OANNi/nw8w0XA4MN IpwfWKSgqrEVwVx4mANH8QiGWd9FFmqOL2AIN5fSUNVvomHevoThj64gB93eBzQ0OXbA+IkJ Gtxft2HonF8HwaPdLJSaIhgsY0UsLP8eYeBC+C8OjrjqKeisvhQt77RwMNBaxsCxpToMbYU3 ooG3/AwMnatiYch4BcHYyWUGJrzR1Kn6EQ7KmqwIvO0NLBwxvQhTLXMc/P29D8N42TZ4WJEH XbZEWOidQjBcd42CZbeLg9/GTjPgs7dRcPVmGMNCSTUL5umjCK5ZzlHQV93MQG3vVSp6xwfg X75PwXeDNhZumcYRDHYGaag8XIbA7gkwMOM20dteJ51TdzFxjdYicqbhOkVC5Q8pEvD0UOSs dZQjNscB4qxPITXuPyliDgxi4mgsZonjn285MuJ3s6S7IkITZ+0hEnJa0HvP7JK9uk/SavIk 3aatmTL1mcW3c32p+Q+MXagQFSebURwvClvEvsl+HNOskCwGAuFHOkFIFWeDF2kzkvFYuLxS vOCsoGKDeOFT8XKkA5kRz9PCOnHJ92asLRfSxMBiJfPYc63Y1NzxyCdOeEn8sfomimlFlPGY a/FjfpV4yXKbjtngaK79B0WsjaOrxpZKXI7k1ico6/+U9QnKhnAjStBk52WpNNq0jfr96oJs Tf7Gz3KyHCj6kicO3v/GheaG0r1I4JFypRwmDWoFo8rTF2R5kchjZYJ8clSnVsj3qQq+knQ5 e3UHtJLei9bwtPJp+VsfSZkK4XOVQdovSbmS7r8pxcclFaKdOwZWePrWN2tT2pO+cHhul+xJ eDdzTVF6+anc6WRTQL35BfWheOeXa+/YZeRYUend/t1e27zhtY6RpzI2bUn7ifkF5yTu/KSl bumd7aOVvw4HQq17Q6uff67n+seH/Zb2nor490M1Hz6bMb3HeC94EHqL0udLNDb/yykabXzi zBurKCWtV6tSU7BOr/oXBAXMeI4DAAA= 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