Re: [PATCH v2 4/5] mm: migrate: add isolate_folio_to_list()

[David Hildenbrand <david@redhat.com>]

>   
> diff --git a/mm/migrate.c b/mm/migrate.c
> index dbfa910ec24b..53f8429a8ebe 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -178,6 +178,33 @@ void putback_movable_pages(struct list_head *l)
>   	}
>   }
>   
> +/* Must be called with an elevated refcount on the non-hugetlb folio */
> +bool isolate_folio_to_list(struct folio *folio, struct list_head *list)
> +{
> +	bool isolated = false;

No need to initialize this to "false".

> +
> +	if (folio_test_hugetlb(folio)) {
> +		isolated = isolate_hugetlb(folio, list);
> +	} else {
> +		bool lru = !__folio_test_movable(folio);
> +
> +		if (lru)
> +			isolated = folio_isolate_lru(folio);
> +		else
> +			isolated = isolate_movable_page(&folio->page,
> +							ISOLATE_UNEVICTABLE);
> +
> +		if (isolated) {
> +			list_add(&folio->lru, list);
> +			if (lru)
> +				node_stat_add_folio(folio, NR_ISOLATED_ANON +
> +						    folio_is_file_lru(folio));
> +		}
> +	}
> +
> +	return isolated;

Revisiting this patch, we should likely do

bool isolated, lru;

if (folio_test_hugetlb(folio))
	return isolate_hugetlb(folio, list);

lru = !__folio_test_movable(folio);
if (lru)
...

if (!isolated)
	return false;

list_add(&folio->lru, list);
if (lru)
	node_stat_add_folio(folio, NR_ISOLATED_ANON +
			    folio_is_file_lru(folio));
return true;


to avoid one indentation level and clean up the code flow a bit.

> +}
> +
>   static bool try_to_map_unused_to_zeropage(struct page_vma_mapped_walk *pvmw,
>   					  struct folio *folio,
>   					  unsigned long idx)

-- 
Cheers,

David / dhildenb