Re: [RFC PATCH 06/14] mm: Remove use of folio list from folios_put()

[Ryan Roberts <ryan.roberts@arm.com>]

On 25/08/2023 14:59, Matthew Wilcox (Oracle) wrote:
> Instead of putting the interesting folios on a list, delete the
> uninteresting one from the folio_batch.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>

> ---
>  mm/swap.c | 17 ++++++++++-------
>  1 file changed, 10 insertions(+), 7 deletions(-)
> 
> diff --git a/mm/swap.c b/mm/swap.c
> index c5ea0c6669e7..6b2f3f77450c 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -959,12 +959,11 @@ void lru_cache_disable(void)
>   */
>  void folios_put(struct folio_batch *folios)
>  {
> -	int i;
> -	LIST_HEAD(pages_to_free);
> +	int i, j;
>  	struct lruvec *lruvec = NULL;
>  	unsigned long flags = 0;
>  
> -	for (i = 0; i < folios->nr; i++) {
> +	for (i = 0, j = 0; i < folios->nr; i++) {
>  		struct folio *folio = folios->folios[i];
>  
>  		if (is_huge_zero_page(&folio->page))
> @@ -1013,14 +1012,18 @@ void folios_put(struct folio_batch *folios)
>  			count_vm_event(UNEVICTABLE_PGCLEARED);
>  		}
>  
> -		list_add(&folio->lru, &pages_to_free);
> +		if (j != i)
> +			folios->folios[j] = folio;
> +		j++;
>  	}
>  	if (lruvec)
>  		unlock_page_lruvec_irqrestore(lruvec, flags);
> +	folios->nr = j;
> +	if (!j)
> +		return;
>  
> -	mem_cgroup_uncharge_list(&pages_to_free);
> -	free_unref_page_list(&pages_to_free);
> -	folios->nr = 0;
> +	mem_cgroup_uncharge_folios(folios);
> +	free_unref_folios(folios);
>  }
>  EXPORT_SYMBOL(folios_put);
>