userfaultfd: correct comment about UFFD_FEATURE_PAGEFAULT_FLAG_WP

Minor comment correction.

Link: http://lkml.kernel.org/r/20161216144821.5183-3-aarcange@redhat.com
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Michael Rapoport <RAPOPORT@il.ibm.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mike Rapoport <rppt@linux.vnet.ibm.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/userfaultfd.c

@@ -169,7 +169,7 @@ static inline struct uffd_msg userfault_msg(unsigned long address,
 	msg.arg.pagefault.address = address;
 	if (flags & FAULT_FLAG_WRITE)
 		/*
-		 * If UFFD_FEATURE_PAGEFAULT_FLAG_WRITE was set in the
+		 * If UFFD_FEATURE_PAGEFAULT_FLAG_WP was set in the
 		 * uffdio_api.features and UFFD_PAGEFAULT_FLAG_WRITE
 		 * was not set in a UFFD_EVENT_PAGEFAULT, it means it
 		 * was a read fault, otherwise if set it means it's