mpenttil@xxxxxxxxxx writes:
> From: Mika Penttilä <mpenttil@xxxxxxxxxx>
>
> Migrating file pages and swapcache pages into device memory is not supported.
> The decision is done based on page_mapping(). For now, swapcache pages are not migrated.
>
> Things can however be improved, for swapcache pages. Try to get rid of the swap cache,
> and if successful, go ahead as with other anonymous pages.
>
> Cc: Alistair Popple <apopple@xxxxxxxxxx>
> Cc: John Hubbard <jhubbard@xxxxxxxxxx>
> Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
> Cc: Huang Ying <ying.huang@xxxxxxxxx>
> Signed-off-by: Mika Penttilä <mpenttil@xxxxxxxxxx>
> ---
>
> v2:
> - use folio_test_anon() (Huang, Ying)
>
>
> mm/migrate_device.c | 24 ++++++++++++++++++------
> 1 file changed, 18 insertions(+), 6 deletions(-)
>
> diff --git a/mm/migrate_device.c b/mm/migrate_device.c
> index d30c9de60b0d..829bbc526758 100644
> --- a/mm/migrate_device.c
> +++ b/mm/migrate_device.c
> @@ -747,13 +747,25 @@ static void __migrate_device_pages(unsigned long *src_pfns,
>
> if (is_device_private_page(newpage) ||
> is_device_coherent_page(newpage)) {
> - /*
> - * For now only support anonymous memory migrating to
> - * device private or coherent memory.
> - */
> +
> if (mapping) {
> - src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
> - continue;
> + struct folio *folio;
> +
> + folio = page_folio(page);
> +
> + /*
> + * For now only support anonymous memory migrating to
> + * device private or coherent memory.
> + *
> + * Try to get rid of swap cache if possible.
I think we can delete the following 2 lines of comments. They add
nothing except what code says already.
Otherwise looks good to me.
Reviewed-by: "Huang, Ying" <ying.huang@xxxxxxxxx>
> + * page is here file or swapcache page, could be shmem also
> + * folio_test_anon() filters out file and shmem
> + *
> + */
> + if (!folio_test_anon(folio) || !folio_free_swap(folio)) {
> + src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
> + continue;
> + }
> }
> } else if (is_zone_device_page(newpage)) {
> /*
