[PATCH] selftests/mm: Fix soft-dirty kselftest supported check

Audra Mitchell
2026-02-18T18:42:27Z

On architectures with separate user address space, such as s390 or
those without an MMU, the call to __access_ok will return true.
The soft-dirty test attempts to check if the PAGEMAP_SCAN feature
is supported by providing an invalid address and expecting
__access_ok to return false, thus throwing an EFAULT error on return.
Because of this assumption, this check will always fail for the
architectures aforementioned. Update the supported check to handle
the return being zero for these types of cases.

Signed-off-by: Audra Mitchell <audra@redhat.com>
---
tools/testing/selftests/mm/vm_util.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/tools/testing/selftests/mm/vm_util.c b/tools/testing/selftests/mm/vm_util.c
index d954bf91afd5..3bb7d322101c 100644
--- a/tools/testing/selftests/mm/vm_util.c
+++ b/tools/testing/selftests/mm/vm_util.c
@@ -77,10 +77,8 @@ static bool pagemap_scan_supported(int fd, char *start)

/* Provide an invalid address in order to trigger EFAULT. */
ret = __pagemap_scan_get_categories(fd, start, (struct page_region *) ~0UL);
- if (ret == 0)
- ksft_exit_fail_msg("PAGEMAP_SCAN succeeded unexpectedly\n");

- supported = errno == EFAULT;
+ supported = (ret == 0) || (errno == EFAULT);

return supported;
}
--
2.52.0