+ mm-mm_init-factor-out-pfn_to_zone.patch added to mm-unstable branch

+ mm-mm_init-factor-out-pfn_to_zone.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/mm_init: factor out pfn_to_zone()
has been added to the -mm mm-unstable branch.  Its filename is
     mm-mm_init-factor-out-pfn_to_zone.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mm_init-factor-out-pfn_to_zone.patch

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

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** 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/mm_init: factor out pfn_to_zone()
Date: Thu, 10 Sep 2026 14:32:45 +0800

pfn_to_zone() in hugetlb_vmemmap.c duplicates the zone lookup logic in
__init_deferred_page().

Move it to mm_init.c, declare it in mm/mm_init.h, and reuse it from
__init_deferred_page() and HugeTLB early vmemmap initialization instead of
open-coding the zone walk there.

Link: https://lore.kernel.org/20260910063256.64386-7-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Qi Zheng <qi.zheng@linux.dev>
Cc: David Hildenbrand (Arm) <david@kernel.org>
Cc: David Laight <david.laight.linux@gmail.com>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/hugetlb_vmemmap.c |   17 ++---------------
 mm/mm_init.c         |   28 ++++++++++++++++++----------
 mm/mm_init.h         |    1 +
 3 files changed, 21 insertions(+), 25 deletions(-)

--- a/mm/hugetlb_vmemmap.c~mm-mm_init-factor-out-pfn_to_zone
+++ a/mm/hugetlb_vmemmap.c
@@ -19,6 +19,7 @@
 #include <asm/tlbflush.h>
 #include "hugetlb_vmemmap.h"
 #include "internal.h"
+#include "mm_init.h"
 
 /**
  * struct vmemmap_remap_walk - walk vmemmap page table
@@ -744,20 +745,6 @@ static bool vmemmap_should_optimize_boot
 	return true;
 }
 
-static struct zone *pfn_to_zone(unsigned nid, unsigned long pfn)
-{
-	struct zone *zone;
-	enum zone_type zone_type;
-
-	for (zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++) {
-		zone = &NODE_DATA(nid)->node_zones[zone_type];
-		if (zone_spans_pfn(zone, pfn))
-			return zone;
-	}
-
-	return NULL;
-}
-
 /*
  * Initialize memmap section for a gigantic page, HVO-style.
  */
@@ -787,7 +774,7 @@ void __init hugetlb_vmemmap_init_early(i
 		map = pfn_to_page(pfn);
 		start = (unsigned long)map;
 		end = start + hugetlb_vmemmap_size(m->hstate);
-		zone = pfn_to_zone(nid, pfn);
+		zone = pfn_to_zone(pfn, nid);
 
 		if (vmemmap_populate_hvo(start, end, huge_page_order(m->hstate),
 					 zone, HUGETLB_VMEMMAP_RESERVE_SIZE))
--- a/mm/mm_init.c~mm-mm_init-factor-out-pfn_to_zone
+++ a/mm/mm_init.c
@@ -692,6 +692,20 @@ static __meminit void pageblock_migratet
 	}
 }
 
+struct zone __meminit *pfn_to_zone(unsigned long pfn, int nid)
+{
+	pg_data_t *pgdat = NODE_DATA(nid);
+
+	for (enum zone_type zone_type = 0; zone_type < MAX_NR_ZONES; zone_type++) {
+		struct zone *zone = &pgdat->node_zones[zone_type];
+
+		if (zone_spans_pfn(zone, pfn))
+			return zone;
+	}
+
+	return NULL;
+}
+
 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
 static inline void pgdat_set_deferred_range(pg_data_t *pgdat)
 {
@@ -750,20 +764,14 @@ defer_init(int nid, unsigned long pfn, u
 
 static void __meminit __init_deferred_page(unsigned long pfn, int nid)
 {
-	pg_data_t *pgdat = NODE_DATA(nid);
-	int zid;
+	struct zone *zone;
 
 	if (early_page_initialised(pfn, nid))
 		return;
 
-	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
-		struct zone *zone = &pgdat->node_zones[zid];
-
-		if (zone_spans_pfn(zone, pfn))
-			break;
-	}
-	__init_single_page(pfn_to_page(pfn), pfn, zid, nid);
-
+	zone = pfn_to_zone(pfn, nid);
+	__init_single_page(pfn_to_page(pfn), pfn,
+			   zone ? zone_idx(zone) : MAX_NR_ZONES, nid);
 	if (pageblock_aligned(pfn)) {
 		enum migratetype mt =
 			kho_scratch_migratetype(pfn, MIGRATE_MOVABLE);
--- a/mm/mm_init.h~mm-mm_init-factor-out-pfn_to_zone
+++ a/mm/mm_init.h
@@ -39,6 +39,7 @@ void memmap_init_range(unsigned long siz
 		enum meminit_context context,
 		struct vmem_altmap *altmap, int migratetype,
 		bool isolate_pageblock);
+struct zone *pfn_to_zone(unsigned long pfn, int nid);
 
 #if defined CONFIG_COMPACTION || defined CONFIG_CMA
 /* Free whole pageblock and set its migration type to MIGRATE_CMA. */
_

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-section-orders.patch
mm-sparse-vmemmap-set-section-order-for-device-dax.patch
mm-sparse-vmemmap-switch-device-dax-to-shared-tail-vmemmap-pages.patch
mm-sparse-vmemmap-move-hvo-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