Re: [PATCH 3/6] mm: migrate_device: use more folio in migrate_device_unmap()

[Alistair Popple <apopple@nvidia.com>]

Kefeng Wang <wangkefeng.wang@huawei.com> writes:

> The page for migrate_device_unmap() already has a reference, so it is
> safe to convert the page to folio to save a few calls to compound_head(),
> which removes the last isolate_lru_page() call.
>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>

Reviewed-by: Alistair Popple <apopple@nvidia.com>

> ---
>  mm/migrate_device.c | 20 ++++++++++----------
>  1 file changed, 10 insertions(+), 10 deletions(-)
>
> diff --git a/mm/migrate_device.c b/mm/migrate_device.c
> index 66db28b89f9b..b49f4956617a 100644
> --- a/mm/migrate_device.c
> +++ b/mm/migrate_device.c
> @@ -379,33 +379,33 @@ static unsigned long migrate_device_unmap(unsigned long *src_pfns,
>  			continue;
>  		}
>  
> -		/* ZONE_DEVICE pages are not on LRU */
> -		if (!is_zone_device_page(page)) {
> -			if (!PageLRU(page) && allow_drain) {
> +		folio =	page_folio(page);
> +		/* ZONE_DEVICE folios are not on LRU */
> +		if (!folio_is_zone_device(folio)) {
> +			if (!folio_test_lru(folio) && allow_drain) {
>  				/* Drain CPU's lru cache */
>  				lru_add_drain_all();
>  				allow_drain = false;
>  			}
>  
> -			if (!isolate_lru_page(page)) {
> +			if (!folio_isolate_lru(folio)) {
>  				src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
>  				restore++;
>  				continue;
>  			}
>  
>  			/* Drop the reference we took in collect */
> -			put_page(page);
> +			folio_put(folio);
>  		}
>  
> -		folio = page_folio(page);
>  		if (folio_mapped(folio))
>  			try_to_migrate(folio, 0);
>  
> -		if (page_mapped(page) ||
> +		if (folio_mapped(folio) ||
>  		    !migrate_vma_check_page(page, fault_page)) {
> -			if (!is_zone_device_page(page)) {
> -				get_page(page);
> -				putback_lru_page(page);
> +			if (!folio_is_zone_device(folio)) {
> +				folio_get(folio);
> +				folio_putback_lru(folio);
>  			}
>  
>  			src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;