[RESEND PATCH v7 01/10] mm: Allow deferred splitting of arbitrary anon large folios

[Barry Song]

> In preparation for the introduction of anonymous small-sized THP, 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 at google.com>
> Reviewed-by: Yin Fengwei <fengwei.yin at intel.com>
> Reviewed-by: Matthew Wilcox (Oracle) <willy at infradead.org>
> Reviewed-by: David Hildenbrand <david at redhat.com>
> Signed-off-by: Ryan Roberts <ryan.roberts at arm.com>
> ---

Reviewed-by: Barry Song <v-songbaohua at oppo.com>

>  mm/rmap.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 7a27a2b41802..49e4d86a4f70 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -1488,11 +1488,11 @@ 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);
>  	}
> --
> 2.25.1

Thanks
Barry