From nobody Mon Feb 9 01:46:11 2026 Received: from invmail4.hynix.com (exvmail4.skhynix.com [166.125.252.92]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 28D7628489B; Thu, 23 Oct 2025 07:44:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=166.125.252.92 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761205473; cv=none; b=EJcUoj9aJsLZKFx6kpA+QX/Wue90n87vphN6rfaNRlF8Ig0KtZMnSYYiOg30FFDkJp7w+tkXiB7I0eMG+XIna1TTZf7tO9JxG82ajQca+KzCZf0jbI51HAES/vQeDMXOOlm8BS2fGhfvL2Xu6dHs2VeiZsp5fo4c5j0KlKfKqFc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1761205473; c=relaxed/simple; bh=JUNLi/65dgjkw16k+x/1hTCjDaNNWT63HXZ+kModT6Q=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References; b=s1L1vpHR4Gw6wRGZkWfK2JCjdIX5l4HfDcIX2G6+LucwN3+7Rxj1nJS2GKJQtMlJyAFLpbB2PJ9w7NJjfJAnY9cBRF2c4BS3TlI7tROidcAk6ppi9NTkf64rd4xdUixX8Bq6thCKYuzjHqwIPTctA9V1eJ0EreYsf+inDjVcMpc= ARC-Authentication-Results: i=1; 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-c2dff70000001609-5a-68f9dcd4f823 From: Byungchul Park To: linux-mm@kvack.org, netdev@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel_team@skhynix.com, harry.yoo@oracle.com, ast@kernel.org, daniel@iogearbox.net, davem@davemloft.net, kuba@kernel.org, hawk@kernel.org, john.fastabend@gmail.com, sdf@fomichev.me, saeedm@nvidia.com, leon@kernel.org, tariqt@nvidia.com, mbloch@nvidia.com, andrew+netdev@lunn.ch, edumazet@google.com, pabeni@redhat.com, akpm@linux-foundation.org, david@redhat.com, lorenzo.stoakes@oracle.com, Liam.Howlett@oracle.com, vbabka@suse.cz, rppt@kernel.org, surenb@google.com, mhocko@suse.com, horms@kernel.org, jackmanb@google.com, hannes@cmpxchg.org, ziy@nvidia.com, ilias.apalodimas@linaro.org, willy@infradead.org, brauner@kernel.org, kas@kernel.org, yuzhao@google.com, usamaarif642@gmail.com, baolin.wang@linux.alibaba.com, almasrymina@google.com, toke@redhat.com, asml.silence@gmail.com, bpf@vger.kernel.org, linux-rdma@vger.kernel.org, sfr@canb.auug.org.au, dw@davidwei.uk, ap420073@gmail.com, dtatulea@nvidia.com Subject: [RFC mm v4 1/2] page_pool: check if nmdesc->pp is !NULL to confirm its usage as pp for net_iov Date: Thu, 23 Oct 2025 16:44:09 +0900 Message-Id: <20251023074410.78650-2-byungchul@sk.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20251023074410.78650-1-byungchul@sk.com> References: <20251023074410.78650-1-byungchul@sk.com> X-Brightmail-Tracker: H4sIAAAAAAAAAzWSa0hTcRjG+59zds5xODgts5NFxaICKbMweYNIoYITYQQSdPlQSw9utqlt uTQIpo0uM2/VaM2Jq0iXWtZM3SRXzmWaUWJoC0vNKFsXi2nLqWTbpG8/nvd5fp9eGhcXCmJo edZJXpUlVUhIISH8EXljQ/+7gCy+qZ0Cc0M9CXVTeVAzYhdAoH4MA3NtM4LJwCAFc22dCCbc z0j41uFDcOuGHwfzKx0BvxumcXC0jiH4arxLwqfOUQrqbCkwXP2ZgEfnW3AYLe0ioVg3g0Nb YJyCQrs1KG7UUtDbXCKAq9O3cWjRjlDwutVMwlD9nAA+u4oJ6DbdIeCXwY3DcEkydFqiwd/z HYG7oQUD/6VKEvqvt2LQ1NZPwZU+CwkfdcMI+jpGCTDMXiChoqAEwcxUUDleNimAiqdDVHIc V+DxkFzH95849/DOW4wbMJYTnMf5HOMcpvcUZ7Hlco3WWE7v6cM5W+1FkrP5LlPcu4FHJNdl nCE4x4etnMM+gXHFZ8fJfYsPCbel8wq5hldt3H5UKJvx1lA51pg8r+umQIvci/UogmaZBPaL uRjTIzrMBaV7QjHJrGM9ngAe4igmnrUaJoMspHGmiGYHnQ/Ch0VMBjv36RoV2hLMGvaNJYwi Zgt79aVi3r6Srbv/JNyOYBLZ7r9PqRCLg5Xe8mkqpGQZN8369Oeo+cFStt3qIcqQyIIW1CKx PEujlMoVCXGy/Cx5XlxattKGgp9RfWb2sB35elNdiKGRJFKU/GxKJhZINep8pQuxNC6JEmkO BiNRujT/NK/KPqLKVfBqF1pGE5Ilos3+U+liJkN6kj/O8zm86v8VoyNitGiVlV+/d5RfuEg8 UJq04JTR27Ti+OHlurH7E97EQHsV7wxUpuQOKoW743K7iMdVKzOEmWlNS9+mRL/WFja8+qHP 7Ks5scOZeuB9oC7ekJjg9aQ0V6qidBWZop6iZhX2h1h7zLT19+rt92L3SU/vX+2Yit5joo1D OyVJIy92bUwSSAi1TLopFleppf8AUtMB3BUDAAA= X-Brightmail-Tracker: H4sIAAAAAAAAAzWRbUhTYRiGe3fOzjkOF4eldjCiWGRWpPb99EEZBL0VWlQo9SeHnrbhnLWp qKHMFCzLr1JaqbSSbKmhzspN1GSb5goqrNXKcsvSssQiTZ1GNoX+XTz3dd9/HoaQfCaDGaU6 hdeoZSopJSJF0Tty171671VEOG6shcqGegrqptLhjscsBG/9FwFU1j5EMO7to2G2vRvBmP0x Bd9tvxBU35wgoPJ5Hgm/G6YJsLR+QfBNf4+Cwe4BGupMUeCuGSKhLb+FgIHiHgoK82YIaPeO 0nDObPQNN+tosFU5hPDiYZEQyqZvE9Ci89DwsrWSgv76WSEMWQtJcFy/S8LPcjsB7qJI6DYE wcTTEQT2hhYBTFyqosB5rVUAD9qdNFzpNVDwKc+NoNc2QEL5n/MUVOQUIZiZ8k2OlowLoaKr n44MxzkuF4VtIz8IfP/uWwF+rS8lsavjiQBbrn+gscGUipuNa3CBq5fAptoLFDb9ukzj96/b KNyjnyGx5eM2bDGPCXBh7ih1OOiEaGcCr1Km8ZrwXXEixczwHfq0MTh92HpLqEP2wALEMBy7 icspPliA/BiKXcW5XF5ijgPYCM5YPu5jEUOwFxmur6NpPljEyrnZwav0XJdkV3JvDPMoZjdz Zc9UcwbHLuPqGjvnbT92C+f420XPscSnvCidpkuQyIAW1KIApTotSaZUbQ7TJioy1Mr0sPjk JBPy/b4m60+pGY2/3GdFLIOk/uLIx1MKiVCWps1IsiKOIaQB4rTjvpM4QZaRyWuST2pSVbzW ipYwpHSx+EAsHydh5bIUPpHnT/Oa/6mA8QvWIb4/2vnqTMjW0OYFuz8sXBG7NzA/tKEuwe5M 9pzqvFZyIjEl+6xn+5Ri2eTepT9Ln8jHxD3Zi1KP1Jg9bnX0HpzZv0MQIg9ambVcrs92NDYP DW70L9PF921wboiKvfB8tTnma1FMNf9On1U8GWXLb696BL8PHU3dH3DM/bTJIonxSkmtQrZ+ DaHRyv4B18DwC/cCAAA= X-CFilter-Loop: Reflected Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" ->pp_magic field in struct page is current used to identify if a page belongs to a page pool. However, ->pp_magic will be removed and page type bit in struct page e.g. PGTY_netpp should be used for that purpose. As a preparation, the check for net_iov, that is not page-backed, should avoid using ->pp_magic since net_iov doens't have to do with page type. Instead, nmdesc->pp can be used if a net_iov or its nmdesc belongs to a page pool, by making sure nmdesc->pp is NULL otherwise. For page-backed netmem, just leave unchanged as is, while for net_iov, make sure nmdesc->pp is initialized to NULL and use nmdesc->pp for the check. Signed-off-by: Byungchul Park Reviewed-by: Mina Almasry --- net/core/devmem.c | 1 + net/core/netmem_priv.h | 8 ++++++++ net/core/page_pool.c | 16 ++++++++++++++-- 3 files changed, 23 insertions(+), 2 deletions(-) diff --git a/net/core/devmem.c b/net/core/devmem.c index d9de31a6cc7f..f81b700f1fd1 100644 --- a/net/core/devmem.c +++ b/net/core/devmem.c @@ -291,6 +291,7 @@ net_devmem_bind_dmabuf(struct net_device *dev, niov =3D &owner->area.niovs[i]; niov->type =3D NET_IOV_DMABUF; niov->owner =3D &owner->area; + niov->desc.pp =3D NULL; page_pool_set_dma_addr_netmem(net_iov_to_netmem(niov), net_devmem_get_dma_addr(niov)); if (direction =3D=3D DMA_TO_DEVICE) diff --git a/net/core/netmem_priv.h b/net/core/netmem_priv.h index 23175cb2bd86..5561fd556bc5 100644 --- a/net/core/netmem_priv.h +++ b/net/core/netmem_priv.h @@ -22,6 +22,14 @@ static inline void netmem_clear_pp_magic(netmem_ref netm= em) =20 static inline bool netmem_is_pp(netmem_ref netmem) { + /* net_iov may be part of a page pool. For net_iov, ->pp in + * net_iov.desc can be used to determine if the pages belong to + * a page pool. Ensure that the ->pp either points to its page + * pool or is set to NULL if it does not. + */ + if (netmem_is_net_iov(netmem)) + return !!netmem_to_nmdesc(netmem)->pp; + return (netmem_get_pp_magic(netmem) & PP_MAGIC_MASK) =3D=3D PP_SIGNATURE; } =20 diff --git a/net/core/page_pool.c b/net/core/page_pool.c index 1a5edec485f1..2756b78754b0 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -699,7 +699,13 @@ s32 page_pool_inflight(const struct page_pool *pool, b= ool strict) void page_pool_set_pp_info(struct page_pool *pool, netmem_ref netmem) { netmem_set_pp(netmem, pool); - netmem_or_pp_magic(netmem, PP_SIGNATURE); + + /* For page-backed, pp_magic is used to identify if it's pp. + * For net_iov, it's ensured nmdesc->pp is non-NULL if it's pp + * and nmdesc->pp is NULL if it's not. + */ + if (!netmem_is_net_iov(netmem)) + netmem_or_pp_magic(netmem, PP_SIGNATURE); =20 /* Ensuring all pages have been split into one fragment initially: * page_pool_set_pp_info() is only called once for every page when it @@ -714,7 +720,13 @@ void page_pool_set_pp_info(struct page_pool *pool, net= mem_ref netmem) =20 void page_pool_clear_pp_info(netmem_ref netmem) { - netmem_clear_pp_magic(netmem); + /* For page-backed, pp_magic is used to identify if it's pp. + * For net_iov, it's ensured nmdesc->pp is non-NULL if it's pp + * and nmdesc->pp is NULL if it's not. + */ + if (!netmem_is_net_iov(netmem)) + netmem_clear_pp_magic(netmem); + netmem_set_pp(netmem, NULL); } =20 --=20 2.17.1