{"id":2219945,"url":"http://patchwork.ozlabs.org/api/1.2/patches/2219945/?format=json","web_url":"http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20260405125240.2558577-21-songmuchun@bytedance.com/","project":{"id":2,"url":"http://patchwork.ozlabs.org/api/1.2/projects/2/?format=json","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":"<20260405125240.2558577-21-songmuchun@bytedance.com>","list_archive_url":"https://lore.kernel.org/linuxppc-dev/20260405125240.2558577-21-songmuchun@bytedance.com/","date":"2026-04-05T12:52:11","name":"[20/49] mm: rename vmemmap optimization macros to generic names","commit_ref":null,"pull_url":null,"state":"new","archived":false,"hash":"df207ac91ff308a3d6be21a171726abf64329101","submitter":{"id":78930,"url":"http://patchwork.ozlabs.org/api/1.2/people/78930/?format=json","name":"Muchun Song","email":"songmuchun@bytedance.com"},"delegate":null,"mbox":"http://patchwork.ozlabs.org/project/linuxppc-dev/patch/20260405125240.2558577-21-songmuchun@bytedance.com/mbox/","series":[{"id":498783,"url":"http://patchwork.ozlabs.org/api/1.2/series/498783/?format=json","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/2219945/comments/","check":"pending","checks":"http://patchwork.ozlabs.org/api/patches/2219945/checks/","tags":{},"related":[],"headers":{"Return-Path":"\n ","X-Original-To":["incoming@patchwork.ozlabs.org","linuxppc-dev@lists.ozlabs.org"],"Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=bytedance.com header.i=@bytedance.com\n header.a=rsa-sha256 header.s=google header.b=CuCmXv6o;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=lists.ozlabs.org\n (client-ip=112.213.38.117; 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Howlett\" ,\n\tVlastimil Babka ,\n\tMike Rapoport ,\n\tSuren Baghdasaryan ,\n\tMichal Hocko ,\n\tNicholas Piggin ,\n\tChristophe Leroy ,\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 ","Subject":"[PATCH 20/49] mm: rename vmemmap optimization macros to generic names","Date":"Sun, 5 Apr 2026 20:52:11 +0800","Message-Id":"<20260405125240.2558577-21-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>","X-Mailing-List":"linuxppc-dev@lists.ozlabs.org","List-Id":"","List-Help":"","List-Owner":"","List-Post":"","List-Archive":",\n ","List-Subscribe":",\n ,\n ","List-Unsubscribe":"","Precedence":"list","MIME-Version":"1.0","Content-Transfer-Encoding":"8bit","X-Spam-Status":"No, score=-0.2 required=3.0 tests=DKIM_SIGNED,DKIM_VALID,\n\tDKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS\n\tautolearn=disabled version=4.0.1 OzLabs 8","X-Spam-Checker-Version":"SpamAssassin 4.0.1 (2024-03-25) on lists.ozlabs.org"},"content":"In preparation for unifying the vmemmap optimization paths for both\nDAX and HugeTLB, rename the existing vmemmap tail page macros to\nmore generic, semantic-based names.\n\nThe original names (e.g., VMEMMAP_TAIL_MIN_ORDER) fail to clearly express\nthe actual requirement: it represents the minimum order of a folio that\ncan satisfy the vmemmap optimization. To provide a broader and clearer\nabstraction for other users like DAX, replace them with newly introduced\nmacros like OPTIMIZABLE_FOLIO_MIN_ORDER and NR_OPTIMIZABLE_FOLIO_SIZES.\n\nThese new macros, along with OPTIMIZED_FOLIO_VMEMMAP_PAGES,\nOPTIMIZED_FOLIO_VMEMMAP_SIZE, and OPTIMIZED_FOLIO_VMEMMAP_PAGE_STRUCTS,\nare explicitly bound to the 'folio' concept. This systematic naming\nmakes it clearer to describe the properties of a vmemmap-optimized\nfolio rather than just raw pages.\n\nSigned-off-by: Muchun Song \n---\n include/linux/mmzone.h | 18 ++++++++++--------\n mm/hugetlb_vmemmap.c | 6 +++---\n mm/sparse-vmemmap.c | 4 ++--\n 3 files changed, 15 insertions(+), 13 deletions(-)","diff":"diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h\nindex 8ee9dc60120a..378feaf4e4ed 100644\n--- a/include/linux/mmzone.h\n+++ b/include/linux/mmzone.h\n@@ -107,13 +107,15 @@\n \t is_power_of_2(sizeof(struct page)) ? \\\n \t MAX_FOLIO_NR_PAGES * sizeof(struct page) : 0)\n \n-/*\n- * vmemmap optimization (like HVO) is only possible for page orders that fill\n- * two or more pages with struct pages.\n- */\n-#define VMEMMAP_TAIL_MIN_ORDER (ilog2(2 * PAGE_SIZE / sizeof(struct page)))\n-#define __NR_VMEMMAP_TAILS (MAX_FOLIO_ORDER - VMEMMAP_TAIL_MIN_ORDER + 1)\n-#define NR_VMEMMAP_TAILS (__NR_VMEMMAP_TAILS > 0 ? __NR_VMEMMAP_TAILS : 0)\n+/* The number of vmemmap pages required by a vmemmap-optimized folio. */\n+#define OPTIMIZED_FOLIO_VMEMMAP_PAGES\t\t1\n+#define OPTIMIZED_FOLIO_VMEMMAP_SIZE\t\t(OPTIMIZED_FOLIO_VMEMMAP_PAGES * PAGE_SIZE)\n+#define OPTIMIZED_FOLIO_VMEMMAP_PAGE_STRUCTS\t(OPTIMIZED_FOLIO_VMEMMAP_SIZE / sizeof(struct page))\n+#define OPTIMIZABLE_FOLIO_MIN_ORDER\t\t(ilog2(OPTIMIZED_FOLIO_VMEMMAP_PAGE_STRUCTS) + 1)\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 \n enum migratetype {\n \tMIGRATE_UNMOVABLE,\n@@ -1144,7 +1146,7 @@ struct zone {\n \tatomic_long_t\t\tvm_stat[NR_VM_ZONE_STAT_ITEMS];\n \tatomic_long_t\t\tvm_numa_event[NR_VM_NUMA_EVENT_ITEMS];\n #ifdef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP\n-\tstruct page *vmemmap_tails[NR_VMEMMAP_TAILS];\n+\tstruct page *vmemmap_tails[NR_OPTIMIZABLE_FOLIO_SIZES];\n #endif\n } ____cacheline_internodealigned_in_smp;\n \ndiff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c\nindex 535f0369a496..d6dd47c232e0 100644\n--- a/mm/hugetlb_vmemmap.c\n+++ b/mm/hugetlb_vmemmap.c\n@@ -495,7 +495,7 @@ static bool vmemmap_should_optimize_folio(const struct hstate *h, struct folio *\n \n static struct page *vmemmap_get_tail(unsigned int order, struct zone *zone)\n {\n-\tconst unsigned int idx = order - VMEMMAP_TAIL_MIN_ORDER;\n+\tconst unsigned int idx = order - OPTIMIZABLE_FOLIO_MIN_ORDER;\n \tstruct page *tail, *p;\n \tint node = zone_to_nid(zone);\n \n@@ -828,7 +828,7 @@ static int __init hugetlb_vmemmap_init(void)\n \tBUILD_BUG_ON(__NR_USED_SUBPAGE > HUGETLB_VMEMMAP_RESERVE_PAGES);\n \n \tfor_each_zone(zone) {\n-\t\tfor (int i = 0; i < NR_VMEMMAP_TAILS; i++) {\n+\t\tfor (int i = 0; i < NR_OPTIMIZABLE_FOLIO_SIZES; i++) {\n \t\t\tstruct page *tail, *p;\n \t\t\tunsigned int order;\n \n@@ -836,7 +836,7 @@ static int __init hugetlb_vmemmap_init(void)\n \t\t\tif (!tail)\n \t\t\t\tcontinue;\n \n-\t\t\torder = i + VMEMMAP_TAIL_MIN_ORDER;\n+\t\t\torder = i + OPTIMIZABLE_FOLIO_MIN_ORDER;\n \t\t\tp = page_to_virt(tail);\n \t\t\tfor (int j = 0; j < PAGE_SIZE / sizeof(struct page); j++)\n \t\t\t\tinit_compound_tail(p + j, NULL, order, zone);\ndiff --git a/mm/sparse-vmemmap.c b/mm/sparse-vmemmap.c\nindex 3fdb6808e8ab..9f70559df4e8 100644\n--- a/mm/sparse-vmemmap.c\n+++ b/mm/sparse-vmemmap.c\n@@ -330,12 +330,12 @@ static __meminit struct page *vmemmap_get_tail(unsigned int order, struct zone *\n \tunsigned int idx;\n \tint node = zone_to_nid(zone);\n \n-\tif (WARN_ON_ONCE(order < VMEMMAP_TAIL_MIN_ORDER))\n+\tif (WARN_ON_ONCE(order < OPTIMIZABLE_FOLIO_MIN_ORDER))\n \t\treturn NULL;\n \tif (WARN_ON_ONCE(order > MAX_FOLIO_ORDER))\n \t\treturn NULL;\n \n-\tidx = order - VMEMMAP_TAIL_MIN_ORDER;\n+\tidx = order - OPTIMIZABLE_FOLIO_MIN_ORDER;\n \ttail = zone->vmemmap_tails[idx];\n \tif (tail)\n \t\treturn tail;\n","prefixes":["20/49"]}