I never had much luck running mm selftests so I spent a few hours digging into why.
Looks like most of the reason is missing SKIP checks, so this series is just adding a bunch of those that I found. I did not do anything like all of them, just the ones I spotted in gup_longterm, gup_test, mmap, userfaultfd and memfd_secret.
It's a bit unfortunate to have to skip those tests when ftruncate() fails, but I don't have time to dig deep enough into it to actually make them pass. I have observed the issue on 9pfs and heard rumours that NFS has a similar problem.
I'm now able to run these test groups successfully:
- mmap - gup_test - compaction - migration - page_frag - userfaultfd - mlock
I've never gone past "Waiting for hugetlb memory to get depleted", in the hugetlb tests. I don't know if they are stuck or if they would eventually work if I was patient enough (testing on a 1G machine). I have not investigated further.
I had some issues with mlock tests failing due to -ENOSRCH from mlock2(), I can no longer reproduce that though, things work OK now.
Of the remaining tests there may be others that work fine, but there's no convenient way to survey the whole output of run_vmtests.sh so I'm just going test by test here.
In my spare moments I am slowly chipping away at a setup to run these tests continuously in a reasonably hermetic QEMU environment via virtme-ng:
https://github.com/bjackman/linux/blob/5fad4b9c592290f38e0f8bc73c9abb9c99d87...
Hopefully that will eventually offer a way to provide a "canned" environment where the tests are known to work, which can be fairly easily reproduced by any developer.
Signed-off-by: Brendan Jackman jackmanb@google.com --- Changes in v4: - NOT ADDRESSED: still using errno==ENOENT as a hacky way to detect buggy filesystems: https://lore.kernel.org/all/CA+i-1C3srkh44tN8dMQ5aD-jhoksUkdEpa+mMfdDtDrPAUv... - Added some incomplete cleanups for the mlock tests. - Fixed divide-by-zero error when running uffd-stress on <32cpu systems. - Fixed misnamed nr_threads variable (now nr_parallel). - Fixed reporting io_uring errors (retval instead of errno). - Link to v3: https://lore.kernel.org/r/20250228-mm-selftests-v3-0-958e3b6f0203@google.com
Changes in v3: - Added fix for userfaultfd tests. - Dropped attempts to use sudo. - Fixed garbage printf in uffd-stress. (Added EXTRA_CFLAGS=-Werror FORCE_TARGETS=1 to my scripts to prevent such errors happening again). - Fixed missing newlines in ksft_test_result_skip() calls. - Link to v2: https://lore.kernel.org/r/20250221-mm-selftests-v2-0-28c4d66383c5@google.com
Changes in v2 (Thanks to Dev for the reviews): - Improve and cleanup some error messages - Add some extra SKIPs - Fix misnaming of nr_cpus variable in uffd tests - Link to v1: https://lore.kernel.org/r/20250220-mm-selftests-v1-0-9bbf57d64463@google.com
--- Brendan Jackman (12): selftests/mm: Report errno when things fail in gup_longterm selftests/mm: Skip uffd-stress if userfaultfd not available selftests/mm: Skip uffd-wp-mremap if userfaultfd not available selftests/mm/uffd: Rename nr_cpus -> nr_parallel selftests/mm: Print some details when uffd-stress gets bad params selftests/mm: Don't fail uffd-stress if too many CPUs selftests/mm: Skip map_populate on weird filesystems selftests/mm: Skip gup_longterm tests on weird filesystems selftests/mm: Drop unnecessary sudo usage selftests/mm: Ensure uffd-wp-mremap gets pages of each size selftests/mm: Skip mlock tests if nobody user can't read it selftests/mm/mlock: Print error on failure
tools/testing/selftests/mm/gup_longterm.c | 45 +++++++++++++++++--------- tools/testing/selftests/mm/map_populate.c | 7 ++++ tools/testing/selftests/mm/mlock-random-test.c | 4 +-- tools/testing/selftests/mm/mlock2.h | 8 ++++- tools/testing/selftests/mm/run_vmtests.sh | 27 ++++++++++++++-- tools/testing/selftests/mm/uffd-common.c | 8 ++--- tools/testing/selftests/mm/uffd-common.h | 2 +- tools/testing/selftests/mm/uffd-stress.c | 42 +++++++++++++++--------- tools/testing/selftests/mm/uffd-unit-tests.c | 2 +- tools/testing/selftests/mm/uffd-wp-mremap.c | 5 ++- 10 files changed, 105 insertions(+), 45 deletions(-) --- base-commit: dcb38e6757f1b7944af9347ce6b54263d3666478 change-id: 20250220-mm-selftests-2d7d0542face
Best regards,