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.
>
> As a detail, do not mess with shmem pages, as they handle swap internally.
>
> Cc: Alistair Popple <apopple@xxxxxxxxxx>
> Cc: John Hubbard <jhubbard@xxxxxxxxxx>
> Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
> Signed-off-by: Mika Penttilä <mpenttil@xxxxxxxxxx>
> ---
> mm/migrate_device.c | 12 ++++++++++--
> 1 file changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/mm/migrate_device.c b/mm/migrate_device.c
> index d30c9de60b0d..e8169c58c341 100644
> --- a/mm/migrate_device.c
> +++ b/mm/migrate_device.c
> @@ -12,6 +12,7 @@
> #include <linux/mmu_notifier.h>
> #include <linux/oom.h>
> #include <linux/pagewalk.h>
> +#include <linux/shmem_fs.h>
> #include <linux/rmap.h>
> #include <linux/swapops.h>
> #include <asm/tlbflush.h>
> @@ -750,10 +751,17 @@ static void __migrate_device_pages(unsigned long *src_pfns,
> /*
> * For now only support anonymous memory migrating to
> * device private or coherent memory.
> + *
> + * Try to get rid of swap cache if possible.
> + * Leave shmem pages alone, they handle swap internally
> + *
> */
> if (mapping) {
> - src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
> - continue;
> + if (shmem_mapping(mapping) ||
> + !folio_free_swap(page_folio(page))) {
Should we filter out file pages firstly?
> + src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
> + continue;
> + }
> }
> } else if (is_zone_device_page(newpage)) {
> /*
Best Regards,
Huang, Ying
