From: David Hildenbrand (Arm) <david@kernel.org>
Date: Fri, 20 Mar 2026 22:13:43 +0000 (+0100)
Subject: mm: prepare to move subsection_map_init() to mm/sparse-vmemmap.c
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=fead6dcff83b02f8d6dc3c1ebbe4e09c05c54ee5;p=thirdparty%2Flinux.git

mm: prepare to move subsection_map_init() to mm/sparse-vmemmap.c

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()".

Link: https://lkml.kernel.org/r/20260320-sparsemem_cleanups-v2-11-096addc8800d@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 3f651baf7e2b5..7cf4a194aea22 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -1982,8 +1982,6 @@ 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 {
@@ -2376,7 +2374,6 @@ 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 62d80fd37ae1f..11b0c91b6d9d5 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -959,12 +959,24 @@ 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 5b261f86ba6f3..4324b93ccebdb 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -1896,7 +1896,7 @@ 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 e2048b1fbf5f7..c96ac5e70c222 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. */