[PATCH 12/27] mm: refactor the ZONE_DEVICE handling in migrate_vma_pages

[Alistair Popple]

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

On Thursday, 10 February 2022 6:28:13 PM AEDT Christoph Hellwig wrote:
> Make the flow a little more clear and prepare for adding a new
> ZONE_DEVICE memory type.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>
> ---
>  mm/migrate.c | 27 ++++++++++++---------------
>  1 file changed, 12 insertions(+), 15 deletions(-)
> 
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 30ecd7223656c1..746e1230886ddb 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -2788,24 +2788,21 @@ void migrate_vma_pages(struct migrate_vma *migrate)
>  
>  		mapping = page_mapping(page);
>  
> -		if (is_zone_device_page(newpage)) {
> -			if (is_device_private_page(newpage)) {
> -				/*
> -				 * For now only support private anonymous when
> -				 * migrating to un-addressable device memory.
> -				 */
> -				if (mapping) {
> -					migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
> -					continue;
> -				}
> -			} else {
> -				/*
> -				 * Other types of ZONE_DEVICE page are not
> -				 * supported.
> -				 */
> +		if (is_device_private_page(newpage)) {
> +			/*
> +			 * For now only support private anonymous when migrating
> +			 * to un-addressable device memory.
> +			 */
> +			if (mapping) {
>  				migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
>  				continue;
>  			}
> +		} else if (is_zone_device_page(newpage)) {
> +			/*
> +			 * Other types of ZONE_DEVICE page are not supported.
> +			 */
> +			migrate->src[i] &= ~MIGRATE_PFN_MIGRATE;
> +			continue;
>  		}
>  
>  		r = migrate_page(mapping, newpage, page, MIGRATE_SYNC_NO_COPY);
>