> On Oct 1, 2026, at 22:42, Mike Rapoport <[email protected]> wrote:
>
> Hi Muchun,
Hi,
>
> On Tue, Sep 29, 2026 at 01:32:31PM +0800, Muchun Song wrote:
>> 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.
>>
>> Signed-off-by: Muchun Song <[email protected]>
>> Acked-by: Qi Zheng <[email protected]>
>> ---
>> v3:
>> - Collect Acked-by from Qi Zheng
>>
>> v2:
>> - New patch.
>> ---
>> mm/mm_init.c | 3 +++
>> 1 file changed, 3 insertions(+)
>>
>> diff --git a/mm/mm_init.c b/mm/mm_init.c
>> index 1650d6bc1211..bd02e8d06965 100644
>> --- a/mm/mm_init.c
>> +++ b/mm/mm_init.c
>> @@ -609,6 +609,9 @@ 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(vmemmap_optimizable_order(pfn_to_section_compound_order(pfn))
>> &&
>> + page_zone_id(page +
>> VMEMMAP_OPTIMIZATION_NR_STRUCT_PAGES) !=
>> + page_zone_id(page));
>
> Hmm, page + VMEMMAP_OPTIMIZATION_NR_STRUCT_PAGES is initialized a tad later
> than page so it'll have stale data in the page->flags, won't it?
Lance is right. The shared tail struct pages are already initialized by
vmemmap_shared_tail_page() during vmemmap population, so they're not stale.
The head 64 struct pages are initialized later — right here, after vmemmap
population.
Thanks,
Muchun
>
>> }
>>
>> #ifdef CONFIG_NUMA
>> --
>> 2.54.0
>>
>
> --
> Sincerely yours,
> Mike.
