Re: [PATCH] mm/huge_memory: add pmd folio to ds_queue in do_huge_zero_wp_pmd()

[Lance Yang <lance.yang@linux.dev>]

On 2025/10/1 22:34, David Hildenbrand wrote:
> On 01.10.25 16:28, Wei Yang wrote:
>> We add pmd folio into ds_queue on the first page fault in
>> __do_huge_pmd_anonymous_page(), so that we can split it in case of
>> memory pressure. This should be the same for a pmd folio during wp
>> page fault.
>>
>> Add it as expected.

Good catch!

>>
>> Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
>> Cc: David Hildenbrand <david@redhat.com>
>> Cc: Lance Yang <lance.yang@linux.dev>
>> Cc: Dev Jain <dev.jain@arm.com>
> 
> Fixes: please, and I think we want CC stable.
> 
>> ---
>>   mm/huge_memory.c | 1 +
>>   1 file changed, 1 insertion(+)
>>
>> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
>> index 1b81680b4225..963cba933cb6 100644
>> --- a/mm/huge_memory.c
>> +++ b/mm/huge_memory.c
>> @@ -1878,6 +1878,7 @@ static vm_fault_t do_huge_zero_wp_pmd(struct 
>> vm_fault *vmf)
>>           goto release;
>>       (void)pmdp_huge_clear_flush(vma, haddr, vmf->pmd);
>>       map_anon_folio_pmd(folio, vmf->pmd, vma, haddr);
>> +    deferred_split_folio(folio, false);
>>       goto unlock;
>>   release:
>>       folio_put(folio);
> 
> Which raises the question whether the deferred_split_folio() should 
> actually go into the map_anon_folio_pmd(). I think you should just move 
> the one from __do_huge_pmd_anonymous_page() in there.

+1 Moving the call into map_anon_folio_pmd() feels way cleaner :)

Cheers,
Lance