[PATCH 26/29] selftests/mm: Workaround no way to detect uffd-minor + wp

Peter Xu
2023-03-30T16:11:52Z

Userfaultfd minor+wp mode was very recently added. The test will fail on
the old kernels at ioctl(UFFDIO_CONTINUE) which is misterious.
Unfortunately there's no feature bit to detect for this support.

Add a hack to leverage WP_UNPOPULATED to detect whether that feature
existed, since WP_UNPOPULATED was merged right after minor+wp.

Signed-off-by: Peter Xu <peterx@redhat.com>
---
tools/testing/selftests/mm/uffd-unit-tests.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/mm/uffd-unit-tests.c b/tools/testing/selftests/mm/uffd-unit-tests.c
index 376dfa320b6f..82fd3aaa06c2 100644
--- a/tools/testing/selftests/mm/uffd-unit-tests.c
+++ b/tools/testing/selftests/mm/uffd-unit-tests.c
@@ -784,7 +784,13 @@ uffd_test_case_t uffd_tests[] = {
.mem_targets = MEM_SHMEM | MEM_HUGETLB,
.uffd_feature_required =
UFFD_FEATURE_MINOR_HUGETLBFS | UFFD_FEATURE_MINOR_SHMEM |
- UFFD_FEATURE_PAGEFAULT_FLAG_WP,
+ UFFD_FEATURE_PAGEFAULT_FLAG_WP |
+ /*
+ * HACK: here we leveraged WP_UNPOPULATED to detect whether
+ * minor mode supports wr-protect. There's no feature flag
+ * for it so this is the best we can test against.
+ */
+ UFFD_FEATURE_WP_UNPOPULATED,
},
{
.name = "minor-collapse",
--
2.39.1