This is a follow up of previous discussion here: https://lore.kernel.org/r/20230324222707.GA3046@monkey There, Mike correctly pointed out that uffd-wp bit can get lost too when Copy-On-Read triggers. Last time we didn't have a reproducer, I finally wrote a reproducer and attached as the last patch. When at it, I decided to also add some more uffd-wp tests against fork(), and I found more bugs. None of them were reported by anyone probably because none of us cares, but since they're still bugs and can be reproduced by the unit test I fixed them too in another patch. The initial patch 1-2 are fixes to bugs, copied stable. The rest patches 3-6 introduces unit tests to verify (based on the recent rework on uffd unit test). Note that not all the bugfixes in patch 1 is verified (e.g. on changes to hugetlb hwpoison / migration entries), but I assume they can be reviewed with careful eyes. Thanks, Peter Xu (6): mm/hugetlb: Fix uffd-wp during fork() mm/hugetlb: Fix uffd-wp bit lost when unsharing happens selftests/mm: Add a few options for uffd-unit-test selftests/mm: Extend and rename uffd pagemap test selftests/mm: Rename COW_EXTRA_LIBS to IOURING_EXTRA_LIBS selftests/mm: Add tests for RO pinning vs fork() mm/hugetlb.c | 33 +- tools/testing/selftests/mm/Makefile | 8 +- tools/testing/selftests/mm/check_config.sh | 4 +- tools/testing/selftests/mm/uffd-unit-tests.c | 318 +++++++++++++++++-- 4 files changed, 315 insertions(+), 48 deletions(-) -- 2.39.1
