mm: enable PTE markers by default

Enable PTE markers by default.  On x86_64 it means it'll auto-enable
PTE_MARKER_UFFD_WP as well.

[peterx@redhat.com: hide PTE_MARKER option]
  Link: https://lkml.kernel.org/r/20220419202531.27415-1-peterx@redhat.com
Link: https://lkml.kernel.org/r/20220405014929.15158-1-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jerome Glisse <jglisse@redhat.com>
Cc: "Kirill A . Shutemov" <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Nadav Amit <nadav.amit@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/Kconfig

@@ -910,14 +910,16 @@ config ANON_VMA_NAME
 	  difference in their name.
 
 config PTE_MARKER
-	bool "Marker PTEs support"
+	bool
 
 	help
 	  Allows to create marker PTEs for file-backed memory.
 
 config PTE_MARKER_UFFD_WP
-	bool "Marker PTEs support for userfaultfd write protection"
-	depends on PTE_MARKER && HAVE_ARCH_USERFAULTFD_WP
+	bool "Userfaultfd write protection support for shmem/hugetlbfs"
+	default y
+	depends on HAVE_ARCH_USERFAULTFD_WP
+	select PTE_MARKER
 
 	help
 	  Allows to create marker PTEs for userfaultfd write protection