Re: [PATCH RFC 05/14] mm/hugetlb: use direct assignment instead of folio_change_private()

[Zi Yan]

On Sun Aug 2, 2026 at 8:16 AM EDT, Usama Arif wrote:
> On Fri, 31 Jul 2026 22:13:28 -0400 Zi Yan <ziy@xxxxxxxxxx> wrote:
>
>> folio_change_private() should be used along with folio_attach_private() and
>> folio_detach_private(), where adding and remove ->private content requires
>> folio refcount change. add_hugetlb_folio() simply sets folio->private to
>> NULL without refcount manipulation. Change it to direct assignment to avoid
>> semantic confusion.
>> 
>> It prepares for a future commit that remove PG_private.
>
>
>> 
>> No funtional change intended.
>> 
>> Assisted-by: Claude:claude-opus-4-8
>> Assisted-by: Codex:gpt-5
>> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
>> To: Muchun Song <muchun.song@xxxxxxxxx>
>> To: Oscar Salvador <osalvador@xxxxxxx>
>> To: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>> Cc: David Hildenbrand <david@xxxxxxxxxx>
>> Cc: linux-mm@xxxxxxxxx
>> Cc: linux-kernel@xxxxxxxxxxxxxxx
>> ---
>>  mm/hugetlb.c | 6 +++---
>>  1 file changed, 3 insertions(+), 3 deletions(-)
>> 
>> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
>> index a77c3c1cb8943..0abaeb47890cb 100644
>> --- a/mm/hugetlb.c
>> +++ b/mm/hugetlb.c
>> @@ -1433,10 +1433,10 @@ void add_hugetlb_folio(struct hstate *h, struct folio *folio,
>>  	}
>>  
>>  	__folio_set_hugetlb(folio);
>> -	folio_change_private(folio, NULL);
>> +	folio->private = NULL;
>>  	/*
>> -	 * We have to set hugetlb_vmemmap_optimized again as above
>> -	 * folio_change_private(folio, NULL) cleared it.
>> +	 * We have to set hugetlb_vmemmap_optimized again as hugetlb page flags
>> +	 * are all cleared above.
>>  	 */
>
> The return value of folio_change_private() is never checked so LGTM.
>
> In the comment, saying "above" is not very clear. How about something like:
>
>         /*
>          * The hugetlb flags live in folio->private, so the assignment
>          * above cleared them all; restore hugetlb_vmemmap_optimized.
>          */
>
> With the comment clearer, feel free to add

Sure.

>
> Acked-by: Usama Arif <usama.arif@xxxxxxxxx>
>

Thanks.

-- 
Best Regards,
Yan, Zi