From nobody Thu Oct 9 04:52:40 2025 Received: from invmail4.hynix.com (exvmail4.skhynix.com [166.125.252.92]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A6B331DC997; Fri, 20 Jun 2025 04:12:35 +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=1750392758; cv=none; b=O65uuWd9SiQibA6MQr6RrELF7BnHKt0PW8sUn6HhLJcArnQjqMzGJSrs6cJ3BfNLNpJZr5yx8KS/cHn8lSQyp8ejAxHvZ9wrJKLGLuDGMxWisyCKjUoC1vwI+OM4eAiGm5mb+4FK9UV0RgXDJnYfDpoxNqCbqgHpI/a9cBXnzIs= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750392758; c=relaxed/simple; bh=AXKtdvnZAsd8KdK5cQFxVAKW+3xp3S98SAL+hOwHAzc=; h=From:To:Cc:Subject:Date:Message-Id; b=XGl0FYpmcGbYPFdJEdWTq4TEb6/2O+n16u6g8iiSVDOi4QifkXJGGJ9673r2IhasH3DU/goekYAcx7dQcaA79d52tPKKLgAO17uIYecqJ0JIyJ3MEYJR1hYvspiJZ2wU/WJ0qbG79Xla3gzWa2LKgGBiDxMRwza1ib4hs6gSunw= 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-669ff7000002311f-48-6854dfb26dca 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, kuba@kernel.org, almasrymina@google.com, ilias.apalodimas@linaro.org, harry.yoo@oracle.com, hawk@kernel.org, akpm@linux-foundation.org, davem@davemloft.net, john.fastabend@gmail.com, andrew+netdev@lunn.ch, asml.silence@gmail.com, toke@redhat.com, tariqt@nvidia.com, edumazet@google.com, pabeni@redhat.com, saeedm@nvidia.com, leon@kernel.org, ast@kernel.org, daniel@iogearbox.net, 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, linux-rdma@vger.kernel.org, bpf@vger.kernel.org, vishal.moola@gmail.com, hannes@cmpxchg.org, ziy@nvidia.com, jackmanb@google.com Subject: [PATCH net-next v6 0/9] Split netmem from struct page Date: Fri, 20 Jun 2025 13:12:15 +0900 Message-Id: <20250620041224.46646-1-byungchul@sk.com> X-Mailer: git-send-email 2.17.1 X-Brightmail-Tracker: H4sIAAAAAAAAAzWRa0hTcRyG+++cnXNcDk7L8qhQtAprmGVM+iFh9iE6BIag9cEIW3powzlt 6pqBqCmI1+yK15hZy2uLKToveZnXSEgNY2Y6mWlZXkpteaNySt8e3of3/fJSmKgZd6cUqjhO rZIpxYQAF8w5lx4zWkPkJ9LavKHYUE1A1YoWXkyY+FBcWY9geXWUhKWuXgLKSu0YFL9Lw+GX YQ2DqR4bCVXGQLDqp3FoSW/AwHa3j4CctHUMXq/Ok3DHVM6DgfpcPjxce45BQ/IECe+bigkY r/7Lh2lzDg5vCitwsOYGQI9uL9jfziLoMjTwwJ5dQsCDIR0Bk2lWBEOdNhyKUnIRGFotfFhf 2dwo6h4nAw6xnbMLGFtXMcJjGwvHSFZnjGdryyVspmUIY42VGQRrXLxPsp8+tBBsX/46zjaa lnhsTuo8wf6c+oizC63DBGuoG8bZfl0XGbQrVHA6glMqNJz6uP81gbzvySQ/ZtpXm/J0A0tG i5JMRFEMLWXSTZGZyGkLy77M4A4maE/GYlnFHOxC+zBLtt7NXEBhdA3BdFWPkg6xm/ZnRjvG CAfj9GHGXtO9xULalxmZGeNtj+5nql61Y44yQ8+RzMzgI/62cGM6yi14HtqpQzsqkUih0kTJ FEqptzxBpdB6h0dHGdHmpfrEjSsmtDgQbEY0hcTOQtNysFzEl2liE6LMiKEwsYuwrO+iXCSM kCXc5tTRYep4JRdrRh4ULnYVnrTfihDRN2RxXCTHxXDq/5ZHObkno6PNTlel09edVaEJX/1M 2bP7orPy97SfeRni9SeswNZUqASr5Jm72fOyNqm2dDTyQOI5wWJG1nLTt+83ay7kecRrhQeT SofOJwaGNYn5rq3Op5JL/Ky/TYNemim3BenM8ucfuRr9gib1rD4/RfI46J5bVVu4/kj/pZIC r9SiEXedGI+Vy3wkmDpW9g/ZxSwrzgIAAA== X-Brightmail-Tracker: H4sIAAAAAAAAAzWRa0hTYRyHe3fOzjmOBoeledAP5UoiIS+Q8O+CCUG9BV4oQfJDespDW943 XVMovEWkaWYFpfOONnWyXKKzVGre6YOlWDPzwsQbmaau4VQqLfr28Hvg+fJjCFk56cEoE1MF VSIfL6ckpCT0VM4x01SEwn+13wN0RgMFjRtaeDFtFoOuoRWB3TlOw3pPPwU1VQ4CdEO5JPw0 bhIw22ejodEUAlN1cyR03GsjwPZwgIKC3C0COp3LNGSb9SLoLhsUw4fWQjE82awloC1zmoaR 1zoKJg2/xTBnKSBhsKSehKnCYOir3A+O90sIeoxtInA8KKPg8XAlBTO5UwiGu20klGYVIjB2 WcWwtbHTKO2dpIO9cffSCoFb6sdEuL1kgsaVpjT8Su+D86zDBDY13Kewaa2Yxl8/dVB44NkW idvN6yJckLNM4dXZLyRe6RqlcM3CDxE2toyS4bIoyelYIV6pEVR+QTESxUD5jDh5LlCbVb1N ZKI1nzzkwnDsca5mfpHcZYo9wlmtTmKXXdkAbt3Wv7NLGIJtorgewzi9K/axQdz4uwlql0nW m3M09f5lKRvIjS1OiP5FD3CNL98SRYipRHsakKsyUZPAK+MDfdVxivREpdb3elKCCe28Vnd7 +5EZ2UfOWxDLIPleqdl+WSET8xp1eoIFcQwhd5XWDIQqZNJYPj1DUCVFq9LiBbUFeTKk3F16 MVKIkbE3+FQhThCSBdV/K2JcPDJR1CX7UGxE/uybjo3vGr/ouxlF+Ue7zhxUFIe515V63XFD bkHnsheM1cGHKvxqU7IdtCHlii4kvXk4kvlYFbvdfvbpwQvarRRbbWZzuKR7u+fk4eciz9Um k36lxct1if+Vcyvvs/KaF77p0qTU+5c4Peybqd/ms4OvdobZ+I4TFXJSreADfAiVmv8DwegM EbECAAA= 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" Hi all, In this version, I'm posting non-controversial patches first. I will post the rest later. This version has no update but adding given 'Reviewed-by's and 'Acked-by's. See the changes below. The MM subsystem is trying to reduce struct page to a single pointer. The first step towards that is splitting struct page by its individual users, as has already been done with folio and slab. This patchset does that for netmem which is used for page pools. Matthew Wilcox tried and stopped the same work, you can see in: https://lore.kernel.org/linux-mm/20230111042214.907030-1-willy@infradead= .org/ Mina Almasry already has done a lot fo prerequisite works by luck. I stacked my patches on the top of his work e.i. netmem. I focused on removing the page pool members in struct page this time, not moving the allocation code of page pool from net to mm. It can be done later if needed. The final patch removing the page pool fields will be submitted once all the converting work of page to netmem are done: 1. converting of libeth_fqe by Tony Nguyen. 2. converting of mlx5 by Tariq Toukan. 3. converting of prueth_swdata. 4. converting of freescale driver. For our discussion, I'm sharing what the final patch looks like the following. Byungchul --8<-- commit 1847d9890f798456b21ccb27aac7545303048492 Author: Byungchul Park Date: Wed May 28 20:44:55 2025 +0900 mm, netmem: remove the page pool members in struct page =20 Now that all the users of the page pool members in struct page have been gone, the members can be removed from struct page. =20 However, since struct netmem_desc still uses the space in struct page, the important offsets should be checked properly, until struct netmem_desc has its own instance from slab. =20 Remove the page pool members in struct page and modify static checkers for the offsets. =20 Signed-off-by: Byungchul Park diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 32ba5126e221..db2fe0d0ebbf 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -120,17 +120,6 @@ struct page { */ unsigned long private; }; - struct { /* page_pool used by netstack */ - /** - * @pp_magic: magic value to avoid recycling non - * page_pool allocated pages. - */ - unsigned long pp_magic; - struct page_pool *pp; - unsigned long _pp_mapping_pad; - unsigned long dma_addr; - atomic_long_t pp_ref_count; - }; struct { /* Tail pages of compound page */ unsigned long compound_head; /* Bit zero is set */ }; diff --git a/include/net/netmem.h b/include/net/netmem.h index 8f354ae7d5c3..3414f184d018 100644 --- a/include/net/netmem.h +++ b/include/net/netmem.h @@ -42,11 +42,8 @@ struct netmem_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); +NETMEM_DESC_ASSERT_OFFSET(lru, pp_magic); +NETMEM_DESC_ASSERT_OFFSET(mapping, _pp_mapping_pad); #undef NETMEM_DESC_ASSERT_OFFSET =20 /* --- Changes from v5 (no actual updates): 1. Rease on net-next/main as of Jun 20. 2. Add given 'Reviewed-by's and 'Acked-by's, thanks to all. 3. Add missing cc's. Changes from v4: 1. Add given 'Reviewed-by's, thanks to all. 2. Exclude potentially controversial patches. Changes from v3: 1. Relocates ->owner and ->type of net_iov out of netmem_desc and make them be net_iov specific. 2. Remove __force when casting struct page to struct netmem_desc. Changes from v2: 1. Introduce a netmem API, virt_to_head_netmem(), and use it when it's needed. 2. Introduce struct netmem_desc as a new struct and union'ed with the existing fields in struct net_iov. 3. Make page_pool_page_is_pp() access ->pp_magic through struct netmem_desc instead of struct page. 4. Move netmem alloc APIs from include/net/netmem.h to net/core/netmem_priv.h. 5. Apply trivial feedbacks, thanks to Mina, Pavel, and Toke. 6. Add given 'Reviewed-by's, thanks to Mina. Changes from v1: 1. Rebase on net-next's main as of May 26. 2. Check checkpatch.pl, feedbacked by SJ Park. 3. Add converting of page to netmem in mt76. 4. Revert 'mlx5: use netmem descriptor and APIs for page pool' since it's on-going by Tariq Toukan. I will wait for his work to be done. 5. Revert 'page_pool: use netmem APIs to access page->pp_magic in page_pool_page_is_pp()' since we need more discussion. 6. Revert 'mm, netmem: remove the page pool members in struct page' since there are some prerequisite works to remove the page pool fields from struct page. I can submit this patch separatedly later. 7. Cancel relocating a page pool member in struct page. 8. Modify static assert for offests and size of struct netmem_desc. Changes from rfc: 1. Rebase on net-next's main branch. https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/ 2. Fix a build error reported by kernel test robot. https://lore.kernel.org/all/202505100932.uzAMBW1y-lkp@intel.com/ 3. Add given 'Reviewed-by's, thanks to Mina and Ilias. 4. Do static_assert() on the size of struct netmem_desc instead of placing place-holder in struct page, feedbacked by Matthew. 5. Do struct_group_tagged(netmem_desc) on struct net_iov instead of wholly renaming it to strcut netmem_desc, feedbacked by Mina and Pavel. Byungchul Park (9): netmem: introduce struct netmem_desc mirroring struct page page_pool: rename page_pool_return_page() to page_pool_return_netmem() page_pool: rename __page_pool_release_page_dma() to __page_pool_release_netmem_dma() page_pool: rename __page_pool_alloc_pages_slow() to __page_pool_alloc_netmems_slow() netmem: use _Generic to cover const casting for page_to_netmem() netmem: remove __netmem_get_pp() page_pool: make page_pool_get_dma_addr() just wrap page_pool_get_dma_addr_netmem() netmem: introduce a netmem API, virt_to_head_netmem() page_pool: access ->pp_magic through struct netmem_desc in page_pool_page_is_pp() include/linux/mm.h | 12 --- include/net/netmem.h | 138 ++++++++++++++++++++++---------- include/net/page_pool/helpers.h | 7 +- mm/page_alloc.c | 1 + net/core/page_pool.c | 36 ++++----- 5 files changed, 117 insertions(+), 77 deletions(-) base-commit: 4f4040ea5d3e4bebebbef9379f88085c8b99221c --=20 2.17.1