linux-kernel - Re: [PATCH 2/2] mm/migrate_device: further convert migrate_device

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Date: Thu, 15 Feb 2024 09:45:16 +1100
From: Alistair Popple <apopple@...dia.com>
To: Sidhartha Kumar <sidhartha.kumar@...cle.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
 akpm@...ux-foundation.org, willy@...radead.org
Subject: Re: [PATCH 2/2] mm/migrate_device: further convert
 migrate_device_finalize() to folios


Sidhartha Kumar <sidhartha.kumar@...cle.com> writes:

> Use folio api functions from the already defined src and dst folio
> variables.
>
> Signed-off-by: Sidhartha Kumar <sidhartha.kumar@...cle.com>
> ---
>  mm/migrate_device.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/mm/migrate_device.c b/mm/migrate_device.c
> index 9152a329b0a68..a48d5cdb28553 100644
> --- a/mm/migrate_device.c
> +++ b/mm/migrate_device.c
> @@ -843,17 +843,17 @@ void migrate_device_finalize(unsigned long *src_pfns,
>  		remove_migration_ptes(src, dst, false);
>  		folio_unlock(src);
>  
> -		if (is_zone_device_page(page))
> -			put_page(page);
> +		if (folio_is_zone_device(src))
> +			folio_put(src);
>  		else
> -			putback_lru_page(page);
> +			folio_putback_lru(src);
>  
>  		if (newpage != page) {
> -			unlock_page(newpage);
> -			if (is_zone_device_page(newpage))
> -				put_page(newpage);

Defining migrate_pfn_to_folio() would also allow the removal of the
newpage and page variables entirely which I think would make this
clearer.

As an aside is there any motivation for making these changes other than
as a general cleanup? I ask only because I have been looking at allowing
device pages with order > 0 so have some of these clean-ups in a local
tree as they're a pre-requisite for that.

 - Alistair

> +			folio_unlock(dst);
> +			if (folio_is_zone_device(dst))
> +				folio_put(dst);
>  			else
> -				putback_lru_page(newpage);
> +				folio_putback_lru(dst);
>  		}
>  	}
>  }