Re: [PATCH v5 2/8] mm/lru: replace pgdat lru_lock with lruvec lock

[Matthew Wilcox]

On Tue, Dec 10, 2019 at 07:46:18PM +0800, Alex Shi wrote:
> -static void lock_page_lru(struct page *page, int *isolated)
> +static struct lruvec *lock_page_lru(struct page *page, int *isolated)
>  {
> -	pg_data_t *pgdat = page_pgdat(page);
> +	struct lruvec *lruvec = lock_page_lruvec_irq(page);
>  
> -	spin_lock_irq(&pgdat->lru_lock);
>  	if (PageLRU(page)) {
> -		struct lruvec *lruvec;
>  
> -		lruvec = mem_cgroup_page_lruvec(page, pgdat);
>  		ClearPageLRU(page);
>  		del_page_from_lru_list(page, lruvec, page_lru(page));
>  		*isolated = 1;
>  	} else
>  		*isolated = 0;
> +
> +	return lruvec;
>  }

I still don't understand how this is supposed to work for !PageLRU
pages.  Which lruvec have you locked if this page isn't on an LRU?