mm/uffd: enable write protection for shmem & hugetlbfs

mm/uffd: enable write protection for shmem & hugetlbfs

We've had all the necessary changes ready for both shmem and hugetlbfs.
Turn on all the shmem/hugetlbfs switches for userfaultfd-wp.

We can expand UFFD_API_RANGE_IOCTLS_BASIC with _UFFDIO_WRITEPROTECT too
because all existing types now support write protection mode.

Since vma_can_userfault() will be used elsewhere, move into userfaultfd_k.h.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peter Xu <[email protected]>
Cc: Alistair Popple <[email protected]>
Cc: Andrea Arcangeli <[email protected]>
Cc: Axel Rasmussen <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Hugh Dickins <[email protected]>
Cc: Jerome Glisse <[email protected]>
Cc: "Kirill A . Shutemov" <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Mike Kravetz <[email protected]>
Cc: Mike Rapoport <[email protected]>
Cc: Nadav Amit <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>