# \[PATCH v2 60/69\] mm/mm\_init: Check zone consistency on optimized vmemmap sections

- From: Muchun Song \<hidden\>
- Date: 2026-05-13 13:22:20 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2026/05/9003737
- Thread: https://ratatoskr.run/linux-mm/2026/05/9003574/t.md

```text
For vmemmap-optimized sections, the shared tail struct pages are reused
across compound pages and should already carry the expected zone and
node.

Warn in __init_single_page() if such a shared tail page is seen with a
different zone or node, which would indicate inconsistent initialization.

Signed-off-by: Muchun Song <redacted>
---
 mm/mm_init.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/mm_init.c b/mm/mm_init.c
index 4ea39392993b..95422e92ede8 100644
--- a/mm/mm_init.c
+++ b/mm/mm_init.c
@@ -605,6 +605,9 @@ void __meminit __init_single_page(struct page *page, unsigned long pfn,
 	if (!is_highmem_idx(zone))
 		set_page_address(page, __va(pfn << PAGE_SHIFT));
 #endif
+	VM_WARN_ON_ONCE(order_vmemmap_optimizable(pfn_to_section_order(pfn)) &&
+			page_zone_id(page + OPTIMIZED_FOLIO_VMEMMAP_NR_STRUCT_PAGES) !=
+			page_zone_id(page));
 }
 
 #ifdef CONFIG_NUMA
-- 
2.54.0


```