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GET /api/1.2/patches/2219958/?format=api
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{
    "id": 2219958,
    "url": "http://patchwork.ozlabs.org/api/1.2/patches/2219958/?format=api",
    "web_url": "http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20260405125240.2558577-34-songmuchun@bytedance.com/",
    "project": {
        "id": 2,
        "url": "http://patchwork.ozlabs.org/api/1.2/projects/2/?format=api",
        "name": "Linux PPC development",
        "link_name": "linuxppc-dev",
        "list_id": "linuxppc-dev.lists.ozlabs.org",
        "list_email": "linuxppc-dev@lists.ozlabs.org",
        "web_url": "https://github.com/linuxppc/wiki/wiki",
        "scm_url": "https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git",
        "webscm_url": "https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/",
        "list_archive_url": "https://lore.kernel.org/linuxppc-dev/",
        "list_archive_url_format": "https://lore.kernel.org/linuxppc-dev/{}/",
        "commit_url_format": "https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?id={}"
    },
    "msgid": "<20260405125240.2558577-34-songmuchun@bytedance.com>",
    "list_archive_url": "https://lore.kernel.org/linuxppc-dev/20260405125240.2558577-34-songmuchun@bytedance.com/",
    "date": "2026-04-05T12:52:24",
    "name": "[33/49] mm: introduce CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION",
    "commit_ref": null,
    "pull_url": null,
    "state": "new",
    "archived": false,
    "hash": "24f1f66db2f8090021a8fecf9265d16665ed94d2",
    "submitter": {
        "id": 78930,
        "url": "http://patchwork.ozlabs.org/api/1.2/people/78930/?format=api",
        "name": "Muchun Song",
        "email": "songmuchun@bytedance.com"
    },
    "delegate": null,
    "mbox": "http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20260405125240.2558577-34-songmuchun@bytedance.com/mbox/",
    "series": [
        {
            "id": 498783,
            "url": "http://patchwork.ozlabs.org/api/1.2/series/498783/?format=api",
            "web_url": "http://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=498783",
            "date": "2026-04-05T12:51:51",
            "name": "mm: Generalize vmemmap optimization for DAX and HugeTLB",
            "version": 1,
            "mbox": "http://patchwork.ozlabs.org/series/498783/mbox/"
        }
    ],
    "comments": "http://patchwork.ozlabs.org/api/patches/2219958/comments/",
    "check": "pending",
    "checks": "http://patchwork.ozlabs.org/api/patches/2219958/checks/",
    "tags": {},
    "related": [],
    "headers": {
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        "From": "Muchun Song <songmuchun@bytedance.com>",
        "To": "Andrew Morton <akpm@linux-foundation.org>,\n\tDavid Hildenbrand <david@kernel.org>,\n\tMuchun Song <muchun.song@linux.dev>,\n\tOscar Salvador <osalvador@suse.de>,\n\tMichael Ellerman <mpe@ellerman.id.au>,\n\tMadhavan Srinivasan <maddy@linux.ibm.com>",
        "Cc": "Lorenzo Stoakes <ljs@kernel.org>,\n\t\"Liam R . Howlett\" <Liam.Howlett@oracle.com>,\n\tVlastimil Babka <vbabka@kernel.org>,\n\tMike Rapoport <rppt@kernel.org>,\n\tSuren Baghdasaryan <surenb@google.com>,\n\tMichal Hocko <mhocko@suse.com>,\n\tNicholas Piggin <npiggin@gmail.com>,\n\tChristophe Leroy <chleroy@kernel.org>,\n\taneesh.kumar@linux.ibm.com,\n\tjoao.m.martins@oracle.com,\n\tlinux-mm@kvack.org,\n\tlinuxppc-dev@lists.ozlabs.org,\n\tlinux-kernel@vger.kernel.org,\n\tMuchun Song <songmuchun@bytedance.com>",
        "Subject": "[PATCH 33/49] mm: introduce CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION",
        "Date": "Sun,  5 Apr 2026 20:52:24 +0800",
        "Message-Id": "<20260405125240.2558577-34-songmuchun@bytedance.com>",
        "X-Mailer": "git-send-email 2.20.1",
        "In-Reply-To": "<20260405125240.2558577-1-songmuchun@bytedance.com>",
        "References": "<20260405125240.2558577-1-songmuchun@bytedance.com>",
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        "X-Spam-Checker-Version": "SpamAssassin 4.0.1 (2024-03-25) on lists.ozlabs.org"
    },
    "content": "Previously, the vmemmap optimization logic in mm/sparse-vmemmap.c was\nclosely tied to HugeTLB via CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP.\nWith recent refactoring (e.g., introducing compound page order to struct\nmem_section), the core vmemmap optimization machinery has become more\ngeneric and can be utilized by other subsystems like DAX.\n\nTo reflect this generalization and decouple the core optimization logic\nfrom HugeTLB-specific configurations, this patch introduces a new common\nKconfig option: CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION.\n\nBoth HugeTLB and DAX now select this generic option, ensuring that the\nshared optimization infrastructure is enabled whenever either subsystem\nrequires it.\n\nSigned-off-by: Muchun Song <songmuchun@bytedance.com>\n---\n fs/Kconfig                 |  1 +\n include/linux/mmzone.h     | 33 ++++++++++++++++++---------------\n include/linux/page-flags.h |  5 +----\n mm/Kconfig                 |  5 +++++\n 4 files changed, 25 insertions(+), 19 deletions(-)",
    "diff": "diff --git a/fs/Kconfig b/fs/Kconfig\nindex e70aa5f0429a..9b56a90e13db 100644\n--- a/fs/Kconfig\n+++ b/fs/Kconfig\n@@ -278,6 +278,7 @@ config HUGETLB_PAGE_OPTIMIZE_VMEMMAP\n \tdef_bool HUGETLB_PAGE\n \tdepends on ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP\n \tdepends on SPARSEMEM_VMEMMAP\n+\tselect SPARSEMEM_VMEMMAP_OPTIMIZATION\n \n config HUGETLB_PMD_PAGE_TABLE_SHARING\n \tdef_bool HUGETLB_PAGE\ndiff --git a/include/linux/mmzone.h b/include/linux/mmzone.h\nindex 75425407e0c4..6edcb0cc46c4 100644\n--- a/include/linux/mmzone.h\n+++ b/include/linux/mmzone.h\n@@ -102,9 +102,9 @@\n  *\n  * HVO which is only active if the size of struct page is a power of 2.\n  */\n-#define MAX_FOLIO_VMEMMAP_ALIGN \\\n-\t(IS_ENABLED(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP) && \\\n-\t is_power_of_2(sizeof(struct page)) ? \\\n+#define MAX_FOLIO_VMEMMAP_ALIGN\t\t\t\t\t\\\n+\t(IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION) &&\t\\\n+\t is_power_of_2(sizeof(struct page)) ?\t\t\t\\\n \t MAX_FOLIO_NR_PAGES * sizeof(struct page) : 0)\n \n /* The number of vmemmap pages required by a vmemmap-optimized folio. */\n@@ -115,7 +115,8 @@\n \n #define __NR_OPTIMIZABLE_FOLIO_SIZES\t\t(MAX_FOLIO_ORDER - OPTIMIZABLE_FOLIO_MIN_ORDER + 1)\n #define NR_OPTIMIZABLE_FOLIO_SIZES\t\t\\\n-\t(__NR_OPTIMIZABLE_FOLIO_SIZES > 0 ? __NR_OPTIMIZABLE_FOLIO_SIZES : 0)\n+\t((__NR_OPTIMIZABLE_FOLIO_SIZES > 0 &&\t\\\n+\t  IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION)) ? __NR_OPTIMIZABLE_FOLIO_SIZES : 0)\n \n enum migratetype {\n \tMIGRATE_UNMOVABLE,\n@@ -2014,7 +2015,7 @@ struct mem_section {\n \t */\n \tstruct page_ext *page_ext;\n #endif\n-#ifdef CONFIG_SPARSEMEM_VMEMMAP\n+#ifdef CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION\n \t/*\n \t * The order of compound pages in this section. Typically, the section\n \t * holds compound pages of this order; a larger compound page will span\n@@ -2194,7 +2195,19 @@ static inline bool pfn_section_first_valid(struct mem_section *ms, unsigned long\n \t*pfn = (*pfn & PAGE_SECTION_MASK) + (bit * PAGES_PER_SUBSECTION);\n \treturn true;\n }\n+#else\n+static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn)\n+{\n+\treturn 1;\n+}\n+\n+static inline bool pfn_section_first_valid(struct mem_section *ms, unsigned long *pfn)\n+{\n+\treturn true;\n+}\n+#endif\n \n+#ifdef CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION\n static inline void section_set_order(struct mem_section *section, unsigned int order)\n {\n \tVM_BUG_ON(section->order && order && section->order != order);\n@@ -2206,16 +2219,6 @@ static inline unsigned int section_order(const struct mem_section *section)\n \treturn section->order;\n }\n #else\n-static inline int pfn_section_valid(struct mem_section *ms, unsigned long pfn)\n-{\n-\treturn 1;\n-}\n-\n-static inline bool pfn_section_first_valid(struct mem_section *ms, unsigned long *pfn)\n-{\n-\treturn true;\n-}\n-\n static inline void section_set_order(struct mem_section *section, unsigned int order)\n {\n }\ndiff --git a/include/linux/page-flags.h b/include/linux/page-flags.h\nindex 0e03d816e8b9..12665b34586c 100644\n--- a/include/linux/page-flags.h\n+++ b/include/linux/page-flags.h\n@@ -208,14 +208,11 @@ enum pageflags {\n static __always_inline bool compound_info_has_mask(void)\n {\n \t/*\n-\t * Limit mask usage to HugeTLB vmemmap optimization (HVO) where it\n-\t * makes a difference.\n-\t *\n \t * The approach with mask would work in the wider set of conditions,\n \t * but it requires validating that struct pages are naturally aligned\n \t * for all orders up to the MAX_FOLIO_ORDER, which can be tricky.\n \t */\n-\tif (!IS_ENABLED(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP))\n+\tif (!IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION))\n \t\treturn false;\n \n \treturn is_power_of_2(sizeof(struct page));\ndiff --git a/mm/Kconfig b/mm/Kconfig\nindex 3cce862088f1..e81aa77182b2 100644\n--- a/mm/Kconfig\n+++ b/mm/Kconfig\n@@ -410,12 +410,17 @@ config SPARSEMEM_VMEMMAP\n \t  pfn_to_page and page_to_pfn operations.  This is the most\n \t  efficient option when sufficient kernel resources are available.\n \n+config SPARSEMEM_VMEMMAP_OPTIMIZATION\n+\tbool\n+\tdepends on SPARSEMEM_VMEMMAP\n+\n #\n # Select this config option from the architecture Kconfig, if it is preferred\n # to enable the feature of HugeTLB/dev_dax vmemmap optimization.\n #\n config ARCH_WANT_OPTIMIZE_DAX_VMEMMAP\n \tbool\n+\tselect SPARSEMEM_VMEMMAP_OPTIMIZATION if SPARSEMEM_VMEMMAP\n \n config ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP\n \tbool\n",
    "prefixes": [
        "33/49"
    ]
}