Add some mix of tests into page_fault_test: memory regions with all the
pairwise combinations of read-only, userfaultfd, and dirty-logging.  For
example, writing into a read-only region which has a hole handled with
userfaultfd.
Signed-off-by: Ricardo Koller <ricarkol@google.com>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221017195834.2295901-15-ricarkol@google.com