Re: [PATCH v7 2/6] userfaultfd: disable huge PMD sharing for MINOR registered VMAs

[Mike Kravetz]

On 2/18/21 4:48 PM, Axel Rasmussen wrote:
> As the comment says: for the MINOR fault use case, although the page
> might be present and populated in the other (non-UFFD-registered) half
> of the mapping, it may be out of date, and we explicitly want userspace
> to get a minor fault so it can check and potentially update the page's
> contents.
> 
> Huge PMD sharing would prevent these faults from occurring for
> suitably aligned areas, so disable it upon UFFD registration.
> 
> Reviewed-by: Peter Xu <peterx@xxxxxxxxxx>
> Signed-off-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>

Thanks,

Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
-- 
Mike Kravetz