Re: [PATCH STABLE v6.1.y] mm/migrate: set swap entry values of THP tail pages properly.

Zi Yan
2024-03-05T16:17:40Z

[-- Attachment #1: Type: text/plain, Size: 1305 bytes --]

On 5 Mar 2024, at 11:13, Zi Yan wrote:

> From: Zi Yan <ziy@nvidia.com>
>
> The tail pages in a THP can have swap entry information stored in their
> private field. When migrating to a new page, all tail pages of the new
> page need to update ->private to avoid future data corruption.

Corresponding swapcache entries need to be updated as well.
e71769ae5260 ("mm: enable thp migration for shmem thp") fixed it already.

Fixes: 616b8371539a ("mm: thp: enable thp migration in generic path")

>
> Signed-off-by: Zi Yan <ziy@nvidia.com>
> ---
> mm/migrate.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index c93dd6a31c31..c5968021fde0 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -423,8 +423,12 @@ int folio_migrate_mapping(struct address_space *mapping,
> if (folio_test_swapbacked(folio)) {
> __folio_set_swapbacked(newfolio);
> if (folio_test_swapcache(folio)) {
> + int i;
> +
> folio_set_swapcache(newfolio);
> - newfolio->private = folio_get_private(folio);
> + for (i = 0; i < nr; i++)
> + set_page_private(folio_page(newfolio, i),
> + page_private(folio_page(folio, i)));
> }
> entries = nr;
> } else {
> --
> 2.43.0

--
Best Regards,
Yan, Zi

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 854 bytes --]