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

[David Hildenbrand <david@redhat.com>]

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.
> 
> 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.

-- 
Cheers

David / dhildenb