Re: [PATCH 6/7] khugepaged: Use a folio throughout collapse_file()

[Vishal Moola <vishal.moola@gmail.com>]

On Wed, Apr 03, 2024 at 06:18:35PM +0100, Matthew Wilcox (Oracle) wrote:
> @@ -1850,28 +1849,27 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
>  				}
>  				/* drain lru cache to help isolate_lru_page() */
>  				lru_add_drain();
> -				page = folio_file_page(folio, index);
> -			} else if (trylock_page(page)) {
> -				get_page(page);
> +			} else if (folio_trylock(folio)) {
> +				folio_get(folio);
>  				xas_unlock_irq(&xas);
>  			} else {
>  				result = SCAN_PAGE_LOCK;
>  				goto xa_locked;
>  			}
>  		} else {	/* !is_shmem */
> -			if (!page || xa_is_value(page)) {
> +			if (!folio || xa_is_value(folio)) {
>  				xas_unlock_irq(&xas);
>  				page_cache_sync_readahead(mapping, &file->f_ra,
>  							  file, index,
>  							  end - index);
>  				/* drain lru cache to help isolate_lru_page() */
>  				lru_add_drain();
> -				page = find_lock_page(mapping, index);
> -				if (unlikely(page == NULL)) {
> +				folio = filemap_lock_folio(mapping, index);
> +				if (unlikely(folio == NULL)) {

filemap_lock_folio() can return an ERR_PTR(), find_lock_page() handles
it internally.