linux-kernel - Re: [PATCH v2 03/10] mm: don't pass "enum lru

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Date:   Tue, 26 Jan 2021 15:14:38 -0700
From:   Yu Zhao <yuzhao@...gle.com>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Hugh Dickins <hughd@...gle.com>,
        Alex Shi <alex.shi@...ux.alibaba.com>,
        Michal Hocko <mhocko@...nel.org>,
        Johannes Weiner <hannes@...xchg.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>,
        Roman Gushchin <guro@...com>, Vlastimil Babka <vbabka@...e.cz>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 03/10] mm: don't pass "enum lru_list" to lru list
 addition functions

On Tue, Jan 26, 2021 at 10:01:11PM +0000, Matthew Wilcox wrote:
> On Fri, Jan 22, 2021 at 03:05:53PM -0700, Yu Zhao wrote:
> > +++ b/mm/swap.c
> > @@ -231,7 +231,7 @@ static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec)
> >  	if (!PageUnevictable(page)) {
> >  		del_page_from_lru_list(page, lruvec, page_lru(page));
> >  		ClearPageActive(page);
> > -		add_page_to_lru_list_tail(page, lruvec, page_lru(page));
> > +		add_page_to_lru_list_tail(page, lruvec);
> >  		__count_vm_events(PGROTATED, thp_nr_pages(page));
> >  	}
> 
> Is it profitable to do ...
> 
> -		del_page_from_lru_list(page, lruvec, page_lru(page));
> +		enum lru_list lru = page_lru(page);
> +		del_page_from_lru_list(page, lruvec, lru);
> 		ClearPageActive(page);
> -		add_page_to_lru_list_tail(page, lruvec, page_lru(page));
> +		lru &= ~LRU_ACTIVE;
> +		add_page_to_lru_list_tail(page, lruvec, lru);

Ok, now we want to trade readability for size. Sure, I'll see how
much we could squeeze.