Re: [RFC PATCH 05/11] shmem: account for large order folios

[Matthew Wilcox]

On Sat, Oct 28, 2023 at 09:15:42PM +0000, Daniel Gomez wrote:
> @@ -856,16 +856,16 @@ unsigned long shmem_partial_swap_usage(struct address_space *mapping,
>  						pgoff_t start, pgoff_t end)
>  {
>  	XA_STATE(xas, &mapping->i_pages, start);
> -	struct page *page;
> +	struct folio *folio;
>  	unsigned long swapped = 0;
>  	unsigned long max = end - 1;
>  
>  	rcu_read_lock();
> -	xas_for_each(&xas, page, max) {
> -		if (xas_retry(&xas, page))
> +	xas_for_each(&xas, folio, max) {
> +		if (xas_retry(&xas, folio))
>  			continue;
> -		if (xa_is_value(page))
> -			swapped++;
> +		if (xa_is_value(folio))
> +			swapped += folio_nr_pages(folio);

... you can't call folio_nr_pages() if xa_is_value().