selftests/vm: anon_cow: hugetlb tests

selftests/vm: anon_cow: hugetlb tests

Let's run all existing test cases with all hugetlb sizes we're able to
detect.

Note that some tests cases still fail. This will, for example, be fixed
once vmsplice properly uses FOLL_PIN instead of FOLL_GET for pinning.
With 2 MiB and 1 GiB hugetlb on x86_64, the expected failures are:

 # [RUN] vmsplice() + unmap in child ... with hugetlb (2048 kB)
 not ok 23 No leak from parent into child
 # [RUN] vmsplice() + unmap in child ... with hugetlb (1048576 kB)
 not ok 24 No leak from parent into child
 # [RUN] vmsplice() before fork(), unmap in parent after fork() ... with hugetlb (2048 kB)
 not ok 35 No leak from child into parent
 # [RUN] vmsplice() before fork(), unmap in parent after fork() ... with hugetlb (1048576 kB)
 not ok 36 No leak from child into parent
 # [RUN] vmsplice() + unmap in parent after fork() ... with hugetlb (2048 kB)
 not ok 47 No leak from child into parent
 # [RUN] vmsplice() + unmap in parent after fork() ... with hugetlb (1048576 kB)
 not ok 48 No leak from child into parent

Link: https://lkml.kernel.org/r/20220927110120.106906-5-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Christoph von Recklinghausen <crecklin@redhat.com>
Cc: Don Dutile <ddutile@redhat.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>