+ mm-sparse-move-mem_section-init-to-sparse_extreme_init.patch added to mm-new branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Subject: mm/sparse: move mem_section init to sparse_extreme_init()
has been added to the -mm mm-new branch.  Its filename is
     mm-sparse-move-mem_section-init-to-sparse_extreme_init.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-sparse-move-mem_section-init-to-sparse_extreme_init.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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------------------------------------------------------
From: "David Hildenbrand (Arm)" <david@kernel.org>
Subject: mm/sparse: move mem_section init to sparse_extreme_init()
Date: Mon, 21 Sep 2026 21:58:53 +0200

Patch series "mm/sparse: remove SECTION_MARKED_PRESENT and further
cleanups", v2.

SECTION_MARKED_PRESENT is really only needed during boot, where we can
instead just rely on SECTION_IS_EARLY_BIT by setting that flag earlier.

Some preparations for doing that conversion and some cleanups in the same
(sparse) area.


This patch (of 13):

Let's just avoid another pair of ifdef inside a function.  While at it,
switch to INTERNODE_CACHE_BYTES by just defining a fallback in cache.h as
well, given that the x86 variant already provides one.

Link: https://lore.kernel.org/20260921-b4-sparsemem_cleanups-v2-0-54d81d65e125@kernel.org
Link: https://lore.kernel.org/20260921-b4-sparsemem_cleanups-v2-1-54d81d65e125@kernel.org
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Qi Zheng <qi.zheng@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Barry Song <baohua@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Brendan Jackman <brendan.jackman@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Jan Kiszka <jan.kiszka@siemens.com>
Cc: Kieran Bingham <kbingham@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
---

 include/linux/cache.h |    1 +
 mm/sparse.c           |   19 ++++++++++++-------
 2 files changed, 13 insertions(+), 7 deletions(-)

--- a/include/linux/cache.h~mm-sparse-move-mem_section-init-to-sparse_extreme_init
+++ a/include/linux/cache.h
@@ -89,6 +89,7 @@
  */
 #ifndef INTERNODE_CACHE_SHIFT
 #define INTERNODE_CACHE_SHIFT L1_CACHE_SHIFT
+#define INTERNODE_CACHE_BYTES (1 << INTERNODE_CACHE_SHIFT)
 #endif
 
 #if !defined(____cacheline_internodealigned_in_smp)
--- a/mm/sparse.c~mm-sparse-move-mem_section-init-to-sparse_extreme_init
+++ a/mm/sparse.c
@@ -103,11 +103,22 @@ int __meminit sparse_index_init(unsigned
 
 	return 0;
 }
+
+static void __init sparse_extreme_init(void)
+{
+	const unsigned long size = sizeof(struct mem_section *) * NR_SECTION_ROOTS;
+
+	mem_section = memblock_alloc_or_panic(size, INTERNODE_CACHE_BYTES);
+}
 #else /* !SPARSEMEM_EXTREME */
 int __meminit sparse_index_init(unsigned long section_nr, int nid)
 {
 	return 0;
 }
+
+static void __init sparse_extreme_init(void)
+{
+}
 #endif
 
 /*
@@ -196,13 +207,7 @@ void __init sparse_sections_init(void)
 	unsigned long start, end;
 	int i, nid;
 
-#ifdef CONFIG_SPARSEMEM_EXTREME
-	unsigned long size, align;
-
-	size = sizeof(struct mem_section *) * NR_SECTION_ROOTS;
-	align = 1 << (INTERNODE_CACHE_SHIFT);
-	mem_section = memblock_alloc_or_panic(size, align);
-#endif
+	sparse_extreme_init();
 
 	for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid)
 		memory_present(nid, start, end);
_

Patches currently in -mm which might be from david@kernel.org are

maintainers-split-up-memory-management-memory-policy-and-migration.patch
maintainers-move-memory-tiering-under-memory-management-numa-placement.patch
maintainers-make-gregory-a-co-maintainer-of-memory-management-numa-placement.patch
selftests-mm-khugepaged-remove-str_dup-usage.patch
mm-sparse-move-mem_section-init-to-sparse_extreme_init.patch
mm-sparse-refactor-sparse_sections_init.patch
mm-sparse-move-initialization-of-section-metadata-to-sparse_metadata_init.patch
mm-sparse-rename-and-cleanup-sparse_init_nid.patch
mm-sparse-cleanup-sparse_init_one_section.patch
mm-sparse-rename-__highest_present_section_nr-to-__highest_used_section_nr.patch
mm-sparse-remove-pfn_in_present_section.patch
mm-sparse-move-__highest_used_section_nr-handling.patch
scripts-gdb-mmpy-remove-fallbacks-for-section_has_mem_map-and-section_is_early.patch
mm-sparse-remove-section_marked_present.patch
mm-sparse-remove-flags-parameter-from-sparse_init_one_section.patch
fs-proc-page-clarify-comment-in-get_max_dump_pfn.patch
mm-memory_hotplug-drop-config_have_arch_pfn_valid-handling-from-pfn_to_online_page.patch