[PATCH v2 11/15] mm: prepare to move subsection_map_init() to mm/sparse-vmemmap.c

David Hildenbrand (Arm)
2026-03-20T22:14:30Z

We want to move subsection_map_init() to mm/sparse-vmemmap.c.

To prepare for getting rid of subsection_map_init() in mm/sparse.c
completely, use a static inline function for !CONFIG_SPARSEMEM_VMEMMAP.

While at it, move the declaration to internal.h and rename it to
"sparse_init_subsection_map()".

Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
---
include/linux/mmzone.h | 3 ---
mm/internal.h | 12 ++++++++++++
mm/mm_init.c | 2 +-
mm/sparse.c | 6 +-----
4 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 7bd0134c241c..b694c69dee04 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -2002,8 +2002,6 @@ struct mem_section_usage {
unsigned long pageblock_flags[0];
};

-void subsection_map_init(unsigned long pfn, unsigned long nr_pages);
-
struct page;
struct page_ext;
struct mem_section {
@@ -2396,7 +2394,6 @@ static inline unsigned long next_present_section_nr(unsigned long section_nr)
#define sparse_vmemmap_init_nid_early(_nid) do {} while (0)
#define sparse_vmemmap_init_nid_late(_nid) do {} while (0)
#define pfn_in_present_section pfn_valid
-#define subsection_map_init(_pfn, _nr_pages) do {} while (0)
#endif /* CONFIG_SPARSEMEM */

/*
diff --git a/mm/internal.h b/mm/internal.h
index f98f4746ac41..5f5c45d80aca 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -960,12 +960,24 @@ void memmap_init_range(unsigned long, int, unsigned long, unsigned long,
unsigned long, enum meminit_context, struct vmem_altmap *, int,
bool);

+/*
+ * mm/sparse.c
+ */
#ifdef CONFIG_SPARSEMEM
void sparse_init(void);
#else
static inline void sparse_init(void) {}
#endif /* CONFIG_SPARSEMEM */

+#ifdef CONFIG_SPARSEMEM_VMEMMAP
+void sparse_init_subsection_map(unsigned long pfn, unsigned long nr_pages);
+#else
+static inline void sparse_init_subsection_map(unsigned long pfn,
+ unsigned long nr_pages)
+{
+}
+#endif /* CONFIG_SPARSEMEM_VMEMMAP */
+
#if defined CONFIG_COMPACTION || defined CONFIG_CMA

/*
diff --git a/mm/mm_init.c b/mm/mm_init.c
index 969048f9b320..3c5f18537cd1 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -1898,7 +1898,7 @@ static void __init free_area_init(void)
pr_info(" node %3d: [mem %#018Lx-%#018Lx]\n", nid,
(u64)start_pfn << PAGE_SHIFT,
((u64)end_pfn << PAGE_SHIFT) - 1);
- subsection_map_init(start_pfn, end_pfn - start_pfn);
+ sparse_init_subsection_map(start_pfn, end_pfn - start_pfn);
}

/* Initialise every node */
diff --git a/mm/sparse.c b/mm/sparse.c
index e2048b1fbf5f..c96ac5e70c22 100644
--- a/mm/sparse.c
+++ b/mm/sparse.c
@@ -185,7 +185,7 @@ static void subsection_mask_set(unsigned long *map, unsigned long pfn,
bitmap_set(map, idx, end - idx + 1);
}

-void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
+void __init sparse_init_subsection_map(unsigned long pfn, unsigned long nr_pages)
{
int end_sec_nr = pfn_to_section_nr(pfn + nr_pages - 1);
unsigned long nr, start_sec_nr = pfn_to_section_nr(pfn);
@@ -207,10 +207,6 @@ void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
nr_pages -= pfns;
}
}
-#else
-void __init subsection_map_init(unsigned long pfn, unsigned long nr_pages)
-{
-}
#endif

/* Record a memory area against a node. */

--
2.43.0