On 09.08.22 06:42, Alex Williamson wrote:
> The below referenced commit makes the same error as 1c563432588d ("mm: fix
> is_pinnable_page against a cma page"), re-interpreting the logic to exclude
> pinning of the zero page, which breaks device assignment with vfio.
>
> Link: https://lore.kernel.org/all/165490039431.944052.12458624139225785964.stgit@omen
> Fixes: f25cbb7a95a2 ("mm: add zone device coherent type memory support")
> Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
> ---
> include/linux/mm.h | 5 ++---
> 1 file changed, 2 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 18e01474cf6b..772279ed7010 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -1544,9 +1544,8 @@ static inline bool is_longterm_pinnable_page(struct page *page)
> if (mt == MIGRATE_CMA || mt == MIGRATE_ISOLATE)
> return false;
> #endif
> - return !(is_device_coherent_page(page) ||
> - is_zone_movable_page(page) ||
> - is_zero_pfn(page_to_pfn(page)));
> + return !(is_device_coherent_page(page) || is_zone_movable_page(page)) ||
> + is_zero_pfn(page_to_pfn(page));
> }
> #else
> static inline bool is_longterm_pinnable_page(struct page *page)
:/ I guess the code was moved just at the time the old code was still in
place, and when rebasing, the diff in the code was ignored.
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
I have patches in the works that will properly break COW here to get
anon pages instead of pinning the shared zeropage, which is questionable
in COW mappings.
--
Thanks,
David / dhildenb
