linux-kernel - Re: [PATCH v2 28/28] gup: Convert check_and_migrate_movable

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Date:   Mon, 10 Jan 2022 23:52:02 -0800
From:   John Hubbard <jhubbard@...dia.com>
To:     "Matthew Wilcox (Oracle)" <willy@...radead.org>, linux-mm@...ck.org
Cc:     Christoph Hellwig <hch@...radead.org>,
        William Kucharski <william.kucharski@...cle.com>,
        linux-kernel@...r.kernel.org, Jason Gunthorpe <jgg@...pe.ca>
Subject: Re: [PATCH v2 28/28] gup: Convert check_and_migrate_movable_pages()
 to use a folio

On 1/9/22 20:24, Matthew Wilcox (Oracle) wrote:
> Switch from head pages to folios.  This removes an assumption that
> THPs are the only way to have a high-order page.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> ---
>   mm/gup.c | 28 ++++++++++++++--------------
>   1 file changed, 14 insertions(+), 14 deletions(-)

Reviewed-by: John Hubbard <jhubbard@...dia.com>


thanks,
-- 
John Hubbard
NVIDIA

> 
> diff --git a/mm/gup.c b/mm/gup.c
> index 1cdd5f2887a8..b2d109626c44 100644
> --- a/mm/gup.c
> +++ b/mm/gup.c
> @@ -1801,41 +1801,41 @@ static long check_and_migrate_movable_pages(unsigned long nr_pages,
>   	bool drain_allow = true;
>   	LIST_HEAD(movable_page_list);
>   	long ret = 0;
> -	struct page *prev_head = NULL;
> -	struct page *head;
> +	struct folio *folio, *prev_folio = NULL;
>   	struct migration_target_control mtc = {
>   		.nid = NUMA_NO_NODE,
>   		.gfp_mask = GFP_USER | __GFP_NOWARN,
>   	};
>   
>   	for (i = 0; i < nr_pages; i++) {
> -		head = compound_head(pages[i]);
> -		if (head == prev_head)
> +		folio = page_folio(pages[i]);
> +		if (folio == prev_folio)
>   			continue;
> -		prev_head = head;
> +		prev_folio = folio;
>   		/*
>   		 * If we get a movable page, since we are going to be pinning
>   		 * these entries, try to move them out if possible.
>   		 */
> -		if (!is_pinnable_page(head)) {
> -			if (PageHuge(head)) {
> -				if (!isolate_huge_page(head, &movable_page_list))
> +		if (!is_pinnable_page(&folio->page)) {
> +			if (folio_test_hugetlb(folio)) {
> +				if (!isolate_huge_page(&folio->page,
> +							&movable_page_list))
>   					isolation_error_count++;
>   			} else {
> -				if (!PageLRU(head) && drain_allow) {
> +				if (!folio_test_lru(folio) && drain_allow) {
>   					lru_add_drain_all();
>   					drain_allow = false;
>   				}
>   
> -				if (isolate_lru_page(head)) {
> +				if (isolate_lru_folio(folio)) {
>   					isolation_error_count++;
>   					continue;
>   				}
> -				list_add_tail(&head->lru, &movable_page_list);
> -				mod_node_page_state(page_pgdat(head),
> +				list_add_tail(&folio->lru, &movable_page_list);
> +				node_stat_mod_folio(folio,
>   						    NR_ISOLATED_ANON +
> -						    page_is_file_lru(head),
> -						    thp_nr_pages(head));
> +						    folio_is_file_lru(folio),
> +						    folio_nr_pages(folio));
>   			}
>   		}
>   	}