[v6] variable-order, large folios for anonymous memory

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

Posted by Ryan Roberts 1 year, 11 months ago

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@google.com>
Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
---
 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);
 	}
-- 
2.25.1

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

Posted by David Hildenbrand 1 year, 11 months ago

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@google.com>
> Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>
> Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Reviewed-by: David Hildenbrand <david@redhat.com>
> Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
> ---
>   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