Re: [Patch v2] mm/huge_memory: use end_folio to terminate anonymous folio remapping

[Wei Yang <richard.weiyang@gmail.com>]

On Mon, Dec 15, 2025 at 10:31:15AM +0800, Barry Song wrote:
>On Mon, Dec 15, 2025 at 8:49 AM Wei Yang <richard.weiyang@gmail.com> wrote:
>>
>> After splitting a large folio, it is necessary to remap the resulting
>> anonymous folios.
>>
>> The current implementation determines the end of the remapping process
>> by counting the number of pages that have been processed.
>>
>> Since the final folio in the sequence, end_folio, is already known and
>> tracked, this commit refactors the remapping loop to leverage end_folio
>> as the termination marker.
>>
>> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
>> Cc: Zi Yan <ziy@nvidia.com>
>>
>> ---
>> v2: move folio assignment in loop
>> ---
>>  mm/huge_memory.c | 13 ++++---------
>>  1 file changed, 4 insertions(+), 9 deletions(-)
>>
>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>> index 40cf59301c21..fe812d9c7807 100644
>> --- a/mm/huge_memory.c
>> +++ b/mm/huge_memory.c
>> @@ -3423,20 +3423,15 @@ bool unmap_huge_pmd_locked(struct vm_area_struct *vma, unsigned long addr,
>>         return __discard_anon_folio_pmd_locked(vma, addr, pmdp, folio);
>>  }
>>
>> -static void remap_page(struct folio *folio, unsigned long nr, int flags)
>> +static void remap_page(struct folio *folio, struct folio *end_folio, int flags)
>>  {
>
>Do we actually see an improvement in readability or performance?
>The existing code feels a bit more readable to me; nr is clearly
>the number of pages :-)
>

Hi, Barry,

Thanks for your review.

Currently end_folio has been used in __folio_split() and
__folio_freeze_and_split_unmapped() as a termination marker. So continue to
use end_folio here as a termination marker looks consistent and improves
readability to me.

But yeah, this is my personal preference. If it is not the case, I am fine to
keep as it is now. :-)

>Thanks
>Barry

-- 
Wei Yang
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