[{"id":3673400,"web_url":"http://patchwork.ozlabs.org/comment/3673400/","msgid":"<2CFBEBBC-5273-48E9-9E5F-1F4599194050@linux.dev>","list_archive_url":null,"date":"2026-04-04T07:35:52","subject":"Re: [PATCH 0/5] mm/sparse-vmemmap: provide generic vmemmap_set_pmd()\n and vmemmap_check_pmd()","submitter":{"id":84878,"url":"http://patchwork.ozlabs.org/api/people/84878/","name":"Muchun Song","email":"muchun.song@linux.dev"},"content":"> On Apr 4, 2026, at 15:17, Muchun Song <songmuchun@bytedance.com> wrote:\n> \n> The two weak functions vmemmap_set_pmd() and vmemmap_check_pmd() are\n> currently no-ops on every architecture, forcing each platform that needs\n> them to duplicate the same handful of lines. Provide a generic implementation:\n> \n> - vmemmap_set_pmd() simply sets a huge PMD with PAGE_KERNEL protection.\n> \n> - vmemmap_check_pmd() verifies that the PMD is present and leaf,\n>  then calls the existing vmemmap_verify() helper.\n> \n> Architectures that need special handling can continue to override the\n> weak symbols; everyone else gets the standard version for free.\n> \n> This series drops the custom implementations in arm64, riscv, loongarch,\n> and sparc, replacing them with the generic implementation introduced\n> in the first patch.\n> \n> Muchun Song (5):\n>  mm/sparse-vmemmap: provide generic vmemmap_set_pmd() and\n>    vmemmap_check_pmd()\n>  arm64/mm: drop vmemmap_pmd helpers and use generic code\n>  riscv/mm: drop vmemmap_pmd helpers and use generic code\n>  loongarch/mm: drop vmemmap_check_pmd helper and use generic code\n>  sparc/mm: drop vmemmap_check_pmd helper and use generic code\n\nHi all,\n\nPlease accept my sincere apologies for the mailing list noise.\n\nDue to an error in my local scripts (failing to clean up the patch\noutput directory before regenerating the series with an updated commit\nrange), multiple duplicate and conflicting patches were accidentally\nsent to the list simultaneously (10 patches in total instead of the\nintended 5).\n\nSorry again for the inconvenience.\n\nThanks,\nMuchun \n\n> \n> arch/arm64/mm/mmu.c      | 14 --------------\n> arch/loongarch/mm/init.c | 11 -----------\n> arch/riscv/mm/init.c     | 13 -------------\n> arch/sparc/mm/init_64.c  | 11 -----------\n> mm/sparse-vmemmap.c      |  7 ++++++-\n> 5 files changed, 6 insertions(+), 50 deletions(-)\n> \n> -- \n> 2.20.1\n>","headers":{"Return-Path":"\n <SRS0=XnLg=CD=vger.kernel.org=sparclinux+bounces-6634-patchwork-incoming=ozlabs.org@ozlabs.org>","X-Original-To":["incoming@patchwork.ozlabs.org","sparclinux@vger.kernel.org"],"Delivered-To":["patchwork-incoming@legolas.ozlabs.org","patchwork-incoming@ozlabs.org"],"Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (1024-bit key;\n unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256\n header.s=key1 header.b=J33Tenz/;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=ozlabs.org\n (client-ip=2404:9400:2221:ea00::3; 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Miller\" <davem@davemloft.net>,\n Andreas Larsson <andreas@gaisler.com>,\n Andrew Morton <akpm@linux-foundation.org>,\n David Hildenbrand <david@kernel.org>,\n WANG Xuerui <kernel@xen0n.name>,\n Alexandre Ghiti <alex@ghiti.fr>,\n Lorenzo Stoakes <ljs@kernel.org>,\n \"Liam R. Howlett\" <Liam.Howlett@oracle.com>,\n Vlastimil Babka <vbabka@kernel.org>,\n Mike Rapoport <rppt@kernel.org>,\n Suren Baghdasaryan <surenb@google.com>,\n Michal Hocko <mhocko@suse.com>,\n Ryan Roberts <ryan.roberts@arm.com>,\n Kevin Brodsky <kevin.brodsky@arm.com>,\n Dev Jain <dev.jain@arm.com>,\n Anshuman Khandual <anshuman.khandual@arm.com>,\n Yang Shi <yang@os.amperecomputing.com>,\n Chaitanya S Prakash <chaitanyas.prakash@arm.com>,\n Yuquan Wang <wangyuquan1236@phytium.com.cn>,\n Petr Tesarik <ptesarik@suse.com>,\n Austin Kim <austin.kim@lge.com>,\n \"Vishal Moola (Oracle)\" <vishal.moola@gmail.com>,\n Junhui Liu <junhui.liu@pigmoral.tech>,\n \"Matthew Wilcox (Oracle)\" <willy@infradead.org>,\n Alex Shi <alexs@kernel.org>,\n Chengkaitao <chengkaitao@kylinos.cn>,\n linux-arm-kernel@lists.infradead.org,\n linux-kernel@vger.kernel.org,\n loongarch@lists.linux.dev,\n linux-riscv@lists.infradead.org,\n sparclinux@vger.kernel.org,\n linux-mm@kvack.org","Content-Transfer-Encoding":"quoted-printable","Message-Id":"<2CFBEBBC-5273-48E9-9E5F-1F4599194050@linux.dev>","References":"<20260404071720.3577290-1-songmuchun@bytedance.com>","To":"Muchun Song <songmuchun@bytedance.com>","X-Migadu-Flow":"FLOW_OUT","X-Spam-Status":"No, score=-1.2 required=5.0 tests=ARC_SIGNED,ARC_VALID,\n\tDKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DMARC_PASS,\n\tHEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,\n\tSPF_PASS autolearn=disabled version=4.0.1","X-Spam-Checker-Version":"SpamAssassin 4.0.1 (2024-03-25) on gandalf.ozlabs.org"}}]