[PATCH v2 0/3] mm/hugetlb: Fix selftest failures with write check

From: Peter Xu
Date: Mon Oct 03 2022 - 20:37:34 EST

- Fix the commit message of patch 1, replacing CoW with wr-unprotect

Currently akpm mm-unstable fails with uffd hugetlb private mapping test
randomly on a write check.

The initial bisection of that points to the recent pmd unshare series, but
it turns out there's no direction relationship with the series but only
some timing change caused the race to start trigger.

The race should be fixed in patch 1. Patch 2 is a trivial cleanup on the
similar race with hugetlb migrations, patch 3 comment on the write check
so when anyone read it again it'll be clear why it's there.


Peter Xu (3):
mm/hugetlb: Fix race condition of uffd missing/minor handling
mm/hugetlb: Use hugetlb_pte_stable in migration race check
mm/selftest: uffd: Explain the write missing fault check

mm/hugetlb.c | 62 ++++++++++++++++++++----
tools/testing/selftests/vm/userfaultfd.c | 22 ++++++++-
2 files changed, 73 insertions(+), 11 deletions(-)