Re: [PATCH 6/9] userfaultfd: disable huge PMD sharing for MINOR registered VMAs

[Peter Xu]

On Fri, Jan 15, 2021 at 11:04:48AM -0800, 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 of the shared mapping, it may be out of date, and we explicitly want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.
> 
> Signed-off-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>

Reviewed-by: Peter Xu <peterx@xxxxxxxxxx>

-- 
Peter Xu