+ mm-mm_init-add-zone-mismatch-warning-during-page-init.patch added to mm-unstable branch

+ mm-mm_init-add-zone-mismatch-warning-during-page-init.patch added to mm-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/mm_init: add zone mismatch warning during page init
has been added to the -mm mm-unstable branch.  Its filename is
     mm-mm_init-add-zone-mismatch-warning-during-page-init.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-add-zone-mismatch-warning-during-page-init.patch

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

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------------------------------------------------------
From: Muchun Song <muchun.song@linux.dev>
Subject: mm/mm_init: add zone mismatch warning during page init
Date: Sat, 10 Oct 2026 15:57:55 +0800

For vmemmap-optimized sections, tail struct pages may be backed by shared
vmemmap pages.  Those shared pages must carry the same page zone ID as the
struct pages initialized for the section.

Warn in __init_single_page() if the shared tail page has a different
page_zone_id(), which would indicate inconsistent initialization.

Link: https://lore.kernel.org/20261010075755.83339-7-songmuchun@bytedance.com
Signed-off-by: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Acked-by: Qi Zheng <qi.zheng@linux.dev>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <chleroy@kernel.org>
Cc: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Cc: Shrikanth Hegde <sshegde@linux.ibm.com>
Cc: Lorenzo Stoakes <ljs@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>
---

 mm/mm_init.c |   10 ++++++++++
 1 file changed, 10 insertions(+)

--- a/mm/mm_init.c~mm-mm_init-add-zone-mismatch-warning-during-page-init
+++ a/mm/mm_init.c
@@ -593,6 +593,15 @@ out:
 	node_states[N_MEMORY] = saved_node_state;
 }
 
+static inline void vmemmap_optimization_verify_zone(struct page *page)
+{
+	const unsigned int order = pfn_to_section_compound_order(page_to_pfn(page));
+
+	VM_WARN_ON_ONCE(vmemmap_optimizable_order(order) &&
+			page_zone_id(page + VMEMMAP_OPTIMIZATION_NR_STRUCT_PAGES) !=
+			page_zone_id(page));
+}
+
 void __meminit __init_single_page(struct page *page, unsigned long pfn,
 				unsigned long zone, int nid)
 {
@@ -609,6 +618,7 @@ void __meminit __init_single_page(struct
 	if (!is_highmem_idx(zone))
 		set_page_address(page, __va(pfn << PAGE_SHIFT));
 #endif
+	vmemmap_optimization_verify_zone(page);
 }
 
 #ifdef CONFIG_NUMA
_

Patches currently in -mm which might be from muchun.song@linux.dev are

mm-sparse-vmemmap-drop-vmemmap_populate_dax.patch
mm-sparse-vmemmap-support-device-dax-in-common-vmemmap-path.patch
mm-sparse-vmemmap-drop-device-dax-specific-population-path.patch
mm-sparse-vmemmap-remove-the-unused-ptpfn-argument.patch
mm-sparse-vmemmap-open-code-vmemmap_populate_address.patch
mm-mm_init-add-zone-mismatch-warning-during-page-init.patch
mm-mm_init-add-zone-mismatch-warning-during-page-init-fix.patch
mm-fix-missing-page-table-destructor-in-pagetable_free.patch
riscv-mm-fix-hotplug-page-table-destructor-handling.patch
riscv-mm-fix-missing-destructor-for-hotplug-pud-tables.patch
arm64-mm-fix-destructor-for-unconstructed-hotplug-page-tables.patch