Re: [PATCH 4/4] mm/page_alloc: remove set_page_private() in prep_compound_tail()

[Zi Yan <ziy@nvidia.com>]

On 29 Jun 2026, at 11:45, Vlastimil Babka (SUSE) wrote:

> On 6/29/26 04:56, Zi Yan wrote:
>> With the subpage->private == 0 check added in a prior commit, any allocated
>> compound page should not have nonzero subpage->private. Remove the
>
> (not "subpage")

Will change it to tail_page.

>
> I think the sentence would be more precise if it said that we now expect
> (and optionally check) tail pages to have zero ->private when they are
> freed, so we can rely on that still being true during subsequent reallocation.
>
> (and if the buddy allocator itself sets it to non-zero due to split/merge of
> buddy pages, it will reset it to zero as well as appropriate, but maybe that
> doesn't need spelling out)

Will fix the commit message like you suggested above.

>
>> unnecessary subpage->private initialization code in compound page
>> preparation.
>>
>> Signed-off-by: Zi Yan <ziy@nvidia.com>
>
> Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>

Thanks.

>
>> ---
>>  mm/internal.h | 1 -
>>  1 file changed, 1 deletion(-)
>>
>> diff --git a/mm/internal.h b/mm/internal.h
>> index 181e79f1d6a2..c96421ce9350 100644
>> --- a/mm/internal.h
>> +++ b/mm/internal.h
>> @@ -895,7 +895,6 @@ static inline void prep_compound_tail(struct page *tail,
>>  {
>>  	tail->mapping = TAIL_MAPPING;
>>  	set_compound_head(tail, head, order);
>> -	set_page_private(tail, 0);
>>  }
>>
>>  static inline void init_compound_tail(struct page *tail,
>>


Best Regards,
Yan, Zi