Re: [PATCH v6 1/9] mm: Allow deferred splitting of arbitrary anon large folios

[David Hildenbrand]

On 29.09.23 13:44, Ryan Roberts wrote:
> In preparation for the introduction of large folios for anonymous
> memory, we would like to be able to split them when they have unmapped
> subpages, in order to free those unused pages under memory pressure. So
> remove the artificial requirement that the large folio needed to be at
> least PMD-sized.
>
> Reviewed-by: Yu Zhao <yuzhao@xxxxxxxxxx>
> Reviewed-by: Yin Fengwei <fengwei.yin@xxxxxxxxx>
> Reviewed-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
> Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
> Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx>
> ---
>   mm/rmap.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 9f795b93cf40..8600bd029acf 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1446,11 +1446,11 @@ void page_remove_rmap(struct page *page, struct vm_area_struct *vma,
>   		__lruvec_stat_mod_folio(folio, idx, -nr);
>   
>   		/*
> -		 * Queue anon THP for deferred split if at least one
> +		 * Queue anon large folio for deferred split if at least one
>   		 * page of the folio is unmapped and at least one page
>   		 * is still mapped.
>   		 */
> -		if (folio_test_pmd_mappable(folio) && folio_test_anon(folio))
> +		if (folio_test_large(folio) && folio_test_anon(folio))
>   			if (!compound || nr < nr_pmdmapped)
>   				deferred_split_folio(folio);
>   	}

This patch can be picked up early I think.

--
Cheers,

David / dhildenb