On 29 Sep 2026, at 6:33, Yeoreum Yun wrote: > Although the child process in collapse_fork*() or collapse_max_ptes_shared() > reports `KSFT_FAIL`, the result is ignored because the test only checks > whether the parent’s page was collapsed into a huge page. > > As a result, the test is considered successful whenever the parent’s page > is a huge page, even if the child test fails, as shown below: > > # > # Run test: collapse_max_ptes_shared (khugepaged:anon) > # Allocate huge page... OK > # Share huge page over fork()... OK > # Trigger CoW on page 1023 of 2048... OK > # Maybe collapse with max_ptes_shared exceeded.... OK > # Trigger CoW on page 1024 of 2048... Fail > Bail out! Unexpected huge page > # Planned tests != run tests (26 != 23) > # Totals: pass:23 fail:0 xfail:0 xpass:0 skip:0 error:0 // child failed. > # Check if parent still has huge page... OK // parent hpage > success > ok 24 collapse_max_ptes_shared // considered as > success > ... > # Totals: pass:26 fail:0 xfail:0 xpass:0 skip:0 error:0 > > To address this, propagate the child’s failure and skip the subsequent > check in the parent. > > Reviewed-by: Baolin Wang <[email protected]> > Reviewed-by: Gregory Price (Meta) <[email protected]> > Reviewed-by: Lorenzo Stoakes (ARM) <[email protected]> > Acked-by: David Hildenbrand (Arm) <[email protected]> > Signed-off-by: Yeoreum Yun <[email protected]> > --- > tools/testing/selftests/mm/khugepaged.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > Makes sense.
Acked-by: Zi Yan <[email protected]> Best Regards, Yan, Zi
