+ mm-sparse-vmemmap-move-vmemmap-optimization-helpers-to-a-public-header.patch added to mm-new branch

+ mm-sparse-vmemmap-move-vmemmap-optimization-helpers-to-a-public-header.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm/sparse-vmemmap: move vmemmap optimization helpers to a public header
has been added to the -mm mm-new branch.  Its filename is
     mm-sparse-vmemmap-move-vmemmap-optimization-helpers-to-a-public-header.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-sparse-vmemmap-move-vmemmap-optimization-helpers-to-a-public-header.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via various
branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there most days

------------------------------------------------------
From: Muchun Song <songmuchun@bytedance.com>
Subject: mm/sparse-vmemmap: move vmemmap optimization helpers to a public header
Date: Fri, 11 Sep 2026 13:02:24 +0800

The vmemmap optimization helpers currently live in mm/sparse.h, which is
an internal MM header.  That works for MM code, but prevents powerpc from
using the same interfaces without including a private header.

Move the declarations and inline helpers to
include/linux/vmemmap-optimization.h.  This is a preparatory change for
powerpc, which has its own vmemmap optimization implementation and needs
to use the common vmemmap optimization interfaces from architecture code.

Link: https://lore.kernel.org/20260911050228.58884-8-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Qi Zheng <qi.zheng@linux.dev>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 MAINTAINERS                          |    1 
 include/linux/vmemmap-optimization.h |   94 +++++++++++++++++++++++++
 mm/hugetlb.c                         |    2 
 mm/hugetlb_vmemmap.c                 |    2 
 mm/sparse.h                          |   76 --------------------
 5 files changed, 98 insertions(+), 77 deletions(-)

diff --git a/include/linux/vmemmap-optimization.h a/include/linux/vmemmap-optimization.h
new file mode 100644
--- /dev/null
+++ a/include/linux/vmemmap-optimization.h
@@ -0,0 +1,94 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * vmemmap-optimization.h
+ *
+ * Generic vmemmap optimization declarations.
+ *
+ * Author: Muchun Song <songmuchun@bytedance.com>
+ */
+#ifndef _LINUX_VMEMMAP_OPTIMIZATION_H
+#define _LINUX_VMEMMAP_OPTIMIZATION_H
+
+#include <linux/align.h>
+#include <linux/log2.h>
+#include <linux/mmdebug.h>
+#include <linux/mmzone.h>
+
+#ifdef CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION
+static inline unsigned int section_compound_order(const struct mem_section *section)
+{
+	return section->compound_page_order;
+}
+
+static inline void section_set_compound_order(struct mem_section *section,
+					      unsigned int order)
+{
+	VM_WARN_ON(section_compound_order(section) && order &&
+		   section_compound_order(section) != order);
+	section->compound_page_order = order;
+}
+
+static inline void section_set_compound_order_range(unsigned long pfn,
+		unsigned long nr_pages, unsigned int order)
+{
+	unsigned long section_nr = pfn_to_section_nr(pfn);
+
+	if (!IS_ALIGNED(pfn | nr_pages, PAGES_PER_SECTION))
+		return;
+
+	for (unsigned long i = 0; i < nr_pages / PAGES_PER_SECTION; i++)
+		section_set_compound_order(__nr_to_section(section_nr + i), order);
+}
+
+static inline unsigned int pfn_to_section_compound_order(unsigned long pfn)
+{
+	return section_compound_order(__pfn_to_section(pfn));
+}
+#else
+static inline unsigned int section_compound_order(const struct mem_section *section)
+{
+	return 0;
+}
+
+static inline void section_set_compound_order(struct mem_section *section,
+					      unsigned int order)
+{
+}
+
+static inline void section_set_compound_order_range(unsigned long pfn,
+		unsigned long nr_pages, unsigned int order)
+{
+}
+
+static inline unsigned int pfn_to_section_compound_order(unsigned long pfn)
+{
+	return 0;
+}
+#endif /* CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION */
+
+static inline bool vmemmap_optimizable_pfn(unsigned long pfn)
+{
+	const unsigned int order = pfn_to_section_compound_order(pfn);
+	const unsigned long nr_pages = 1UL << order;
+
+	if (!is_power_of_2(sizeof(struct page)))
+		return false;
+
+	return (pfn & (nr_pages - 1)) >= VMEMMAP_OPTIMIZATION_NR_STRUCT_PAGES;
+}
+
+static inline bool vmemmap_optimizable_order(unsigned int order)
+{
+	if (!IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION))
+		return false;
+
+	if (!is_power_of_2(sizeof(struct page)))
+		return false;
+
+	return order >= VMEMMAP_OPTIMIZATION_MIN_ORDER;
+}
+
+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+struct page *vmemmap_shared_tail_page(unsigned int order, struct zone *zone);
+#endif /* CONFIG_SPARSEMEM_VMEMMAP */
+#endif /* _LINUX_VMEMMAP_OPTIMIZATION_H */
--- a/MAINTAINERS~mm-sparse-vmemmap-move-vmemmap-optimization-helpers-to-a-public-header
+++ a/MAINTAINERS
@@ -12096,6 +12096,7 @@ F:	Documentation/mm/hugetlbfs_reserv.rst
 F:	Documentation/mm/vmemmap_dedup.rst
 F:	fs/hugetlbfs/
 F:	include/linux/hugetlb.h
+F:	include/linux/vmemmap-optimization.h
 F:	include/trace/events/hugetlbfs.h
 F:	mm/hugetlb.c
 F:	mm/hugetlb_cgroup.c
--- a/mm/hugetlb.c~mm-sparse-vmemmap-move-vmemmap-optimization-helpers-to-a-public-header
+++ a/mm/hugetlb.c
@@ -38,6 +38,7 @@
 #include <linux/mm_inline.h>
 #include <linux/padata.h>
 #include <linux/pgalloc.h>
+#include <linux/vmemmap-optimization.h>
 
 #include <asm/page.h>
 #include <asm/tlb.h>
@@ -52,7 +53,6 @@
 #include "hugetlb_cma.h"
 #include "hugetlb_internal.h"
 #include "mm_init.h"
-#include "sparse.h"
 #include <linux/page-isolation.h>
 
 #define HUGE_BOOTMEM_ZONES_VALID	BIT(0)
--- a/mm/hugetlb_vmemmap.c~mm-sparse-vmemmap-move-vmemmap-optimization-helpers-to-a-public-header
+++ a/mm/hugetlb_vmemmap.c
@@ -15,10 +15,10 @@
 #include <linux/mmdebug.h>
 #include <linux/pagewalk.h>
 #include <linux/pgalloc.h>
+#include <linux/vmemmap-optimization.h>
 
 #include <asm/tlbflush.h>
 #include "hugetlb_vmemmap.h"
-#include "sparse.h"
 #include "internal.h"
 
 /**
--- a/mm/sparse.h~mm-sparse-vmemmap-move-vmemmap-optimization-helpers-to-a-public-header
+++ a/mm/sparse.h
@@ -9,80 +9,7 @@
 #define __MM_SPARSE_H
 
 #include <linux/mmzone.h>
-
-#ifdef CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION
-static inline unsigned int section_compound_order(const struct mem_section *section)
-{
-	return section->compound_page_order;
-}
-
-static inline void section_set_compound_order(struct mem_section *section,
-					      unsigned int order)
-{
-	VM_WARN_ON(section_compound_order(section) && order &&
-		   section_compound_order(section) != order);
-	section->compound_page_order = order;
-}
-
-static inline void section_set_compound_order_range(unsigned long pfn,
-		unsigned long nr_pages, unsigned int order)
-{
-	unsigned long section_nr = pfn_to_section_nr(pfn);
-
-	if (!IS_ALIGNED(pfn | nr_pages, PAGES_PER_SECTION))
-		return;
-
-	for (unsigned long i = 0; i < nr_pages / PAGES_PER_SECTION; i++)
-		section_set_compound_order(__nr_to_section(section_nr + i), order);
-}
-
-static inline unsigned int pfn_to_section_compound_order(unsigned long pfn)
-{
-	return section_compound_order(__pfn_to_section(pfn));
-}
-#else
-static inline unsigned int section_compound_order(const struct mem_section *section)
-{
-	return 0;
-}
-
-static inline void section_set_compound_order(struct mem_section *section,
-					      unsigned int order)
-{
-}
-
-static inline void section_set_compound_order_range(unsigned long pfn,
-		unsigned long nr_pages, unsigned int order)
-{
-}
-
-static inline unsigned int pfn_to_section_compound_order(unsigned long pfn)
-{
-	return 0;
-}
-#endif
-
-static inline bool vmemmap_optimizable_pfn(unsigned long pfn)
-{
-	const unsigned int order = pfn_to_section_compound_order(pfn);
-	const unsigned long nr_pages = 1UL << order;
-
-	if (!is_power_of_2(sizeof(struct page)))
-		return false;
-
-	return (pfn & (nr_pages - 1)) >= VMEMMAP_OPTIMIZATION_NR_STRUCT_PAGES;
-}
-
-static inline bool vmemmap_optimizable_order(unsigned int order)
-{
-	if (!IS_ENABLED(CONFIG_SPARSEMEM_VMEMMAP_OPTIMIZATION))
-		return false;
-
-	if (!is_power_of_2(sizeof(struct page)))
-		return false;
-
-	return order >= VMEMMAP_OPTIMIZATION_MIN_ORDER;
-}
+#include <linux/vmemmap-optimization.h>
 
 /*
  * mm/sparse.c
@@ -142,7 +69,6 @@ static inline void sparse_sections_init(
  * mm/sparse-vmemmap.c
  */
 #ifdef CONFIG_SPARSEMEM_VMEMMAP
-struct page *vmemmap_shared_tail_page(unsigned int order, struct zone *zone);
 void sparse_init_subsection_map(void);
 int section_nr_vmemmap_pages(unsigned long pfn, unsigned long nr_pages,
 		struct vmem_altmap *altmap, struct dev_pagemap *pgmap);
_

Patches currently in -mm which might be from songmuchun@bytedance.com are

mm-sparse-relax-struct-mem_section-size-constraints.patch
mm-sparse-vmemmap-rename-hvo-order-macros.patch
mm-mm_init-skip-initializing-shared-vmemmap-tail-pages.patch
mm-sparse-vmemmap-initialize-shared-tail-vmemmap-pages-on-allocation.patch
mm-sparse-vmemmap-support-section-based-vmemmap-accounting.patch
mm-mm_init-factor-out-pfn_to_zone.patch
mm-sparse-vmemmap-move-helpers-ahead-of-future-callers.patch
mm-sparse-vmemmap-support-section-based-vmemmap-optimization.patch
mm-sparse-initialize-memory-sections-earlier.patch
mm-hugetlb-switch-hugetlb-to-section-based-vmemmap-optimization.patch
mm-sparse-vmemmap-remove-sparsemem_vmemmap_preinit-support.patch
mm-sparse-inline-usemap-allocation-into-sparse_init_nid.patch
mm-sparse-remove-section_map_size.patch
mm-hugetlb-remove-huge_bootmem_hvo.patch
mm-hugetlb-remove-huge_bootmem_cma.patch
mm-hugetlb-localize-struct-huge_bootmem_page.patch
mm-hugetlb-localize-huge_bootmem_zones_valid.patch
mm-sparse-vmemmap-introduce-config_sparsemem_vmemmap_optimization.patch
mm-sparse-vmemmap-factor-out-shared-vmemmap-tail-page-allocation.patch
mm-sparse-vmemmap-open-code-init_compound_tail.patch
mm-sparse-vmemmap-prepare-dax-vmemmap-population-for-compound-page-orders.patch
mm-sparse-vmemmap-set-compound-page-order-for-device-dax.patch
mm-sparse-vmemmap-switch-device-dax-to-shared-tail-vmemmap-pages.patch
mm-sparse-vmemmap-move-vmemmap-optimization-helpers-to-a-public-header.patch
powerpc-mm-switch-device-dax-to-shared-tail-vmemmap-pages.patch
mm-sparse-vmemmap-drop-the-extra-tail-page-from-device-dax-reservation.patch
mm-sparse-vmemmap-drop-unused-section_nr_vmemmap_pages-arguments.patch
documentation-mm-update-dax-vmemmap-deduplication-docs.patch