On Mon, 24 Jan 2022, Muchun Song wrote:
> The D-cache maintenance inside move_to_new_page() only consider one page,
> there is still D-cache maintenance issue for tail pages of THP. Fix this
> by not using flush_dcache_folio() since it is not backportable.
>
The mention of being backportable suggests that we should backport this,
likely to 4.14+. So should it be marked as stable?
That aside, should there be a follow-up patch that converts to using
flush_dcache_folio()?
> Fixes: 616b8371539a ("mm: thp: enable thp migration in generic path")
> Signed-off-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
> ---
> Changes in v2:
> - Using a for loop instead of the folio variant for backportable.
>
> mm/migrate.c | 7 +++++--
> 1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index c9296d63878d..c418e8d92b9c 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -933,9 +933,12 @@ static int move_to_new_page(struct page *newpage, struct page *page,
> if (!PageMappingFlags(page))
> page->mapping = NULL;
>
> - if (likely(!is_zone_device_page(newpage)))
> - flush_dcache_page(newpage);
> + if (likely(!is_zone_device_page(newpage))) {
> + int i, nr = compound_nr(newpage);
>
> + for (i = 0; i < nr; i++)
> + flush_dcache_page(newpage + i);
> + }
> }
> out:
> return rc;
> --
> 2.11.0
>
>
>
