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

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

[Yu Zhao]

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

Signed-off-by: Yu Zhao <yuzhao@google.com>
---
 mm/swap.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/mm/swap.c b/mm/swap.c
index ae300397dfda..0226c5346560 100644
--- 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.
 		 */
-		list_move_tail(&page->lru, &lruvec->lists[lru]);
+		add_page_to_lru_list_tail(page, lruvec, lru);
 		__count_vm_event(PGROTATED);
 	}
 
@@ -844,17 +844,15 @@ void lru_add_page_tail(struct page *page, struct page *page_tail,
 		get_page(page_tail);
 		list_add_tail(&page_tail->lru, list);
 	} else {
-		struct list_head *list_head;
 		/*
 		 * Head page has not yet been counted, as an hpage,
 		 * so we must account for each subpage individually.
 		 *
-		 * Use the standard add function to put page_tail on the list,
-		 * but then correct its position so they all end up in order.
+		 * Put page_tail on the list at the correct position
+		 * so they all end up in order.
 		 */
-		add_page_to_lru_list(page_tail, lruvec, page_lru(page_tail));
-		list_head = page_tail->lru.prev;
-		list_move_tail(&page_tail->lru, list_head);
+		add_page_to_lru_list_tail(page_tail, lruvec,
+					  page_lru(page_tail));
 	}
 
 	if (!PageUnevictable(page))
-- 
2.22.0.510.g264f2c817a-goog

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

[Andrew Morton]

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);
>  	}

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

[Minchan Kim]

Hi Andrew,

On Wed, Jul 24, 2019 at 07:32:49PM -0700, Andrew Morton wrote:
> 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?

It meant "normal deactivation from the pagevec full". The sentence is
very odd to me, too. ;-( 
Let's remove the weird comment in this chance.

Thanks.