Re: [PATCH] mm: replace list_move_tail() with add_page_to_lru_list_tail()

[Andrew Morton <akpm@linux-foundation.org>]

On Tue, 16 Jul 2019 15:24:36 -0600 Yu Zhao <yuzhao@google.com> wrote:

> This is a cleanup patch that replaces two historical uses of
> list_move_tail() with relatively recent add_page_to_lru_list_tail().
> 

Looks OK to me.

> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -515,7 +515,6 @@ static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec,
>  	del_page_from_lru_list(page, lruvec, lru + active);
>  	ClearPageActive(page);
>  	ClearPageReferenced(page);
> -	add_page_to_lru_list(page, lruvec, lru);
>  
>  	if (PageWriteback(page) || PageDirty(page)) {
>  		/*
> @@ -523,13 +522,14 @@ static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec,
>  		 * It can make readahead confusing.  But race window
>  		 * is _really_ small and  it's non-critical problem.
>  		 */
> +		add_page_to_lru_list(page, lruvec, lru);
>  		SetPageReclaim(page);
>  	} else {
>  		/*
>  		 * The page's writeback ends up during pagevec
>  		 * We moves tha page into tail of inactive.
>  		 */

That comment is really hard to follow.  Minchan, can you please explain
the first sentence?

The second sentence can simply be removed.

> -		list_move_tail(&page->lru, &lruvec->lists[lru]);
> +		add_page_to_lru_list_tail(page, lruvec, lru);
>  		__count_vm_event(PGROTATED);
>  	}