[PATCH v2 0/9] selftests/mm: Some cleanups from trying to run them

[Brendan Jackman <jackmanb@google.com>]

I never had much luck running mm selftests so I spent a couple of 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 observed these issues on both 9p and virtiofs. Probably
it requires digging into the filesystem implementation

(An alternative might just be to mount a tmpfs in the test script).

I am also seeing some failures to allocate hugetlb pages in
uffd-mp-mremap that I have not had time to fully understand, you can see
those here:

https://gist.github.com/bjackman/af74c3a6e60975e6ff0d760cba1e05d2#file-userfaultfd-log

Signed-off-by: Brendan Jackman <jackmanb@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 (9):
      selftests/mm: Report errno when things fail in gup_longterm
      selftests/mm: Fix assumption that sudo is present
      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_threads
      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_longerm tests on weird filesystems

 tools/testing/selftests/mm/gup_longterm.c    | 45 ++++++++++++++++++----------
 tools/testing/selftests/mm/map_populate.c    |  7 +++++
 tools/testing/selftests/mm/run_vmtests.sh    | 22 +++++++++++---
 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 +++-
 8 files changed, 90 insertions(+), 43 deletions(-)
---
base-commit: a3daad8215143340c0870c5489e599fd059037e9
change-id: 20250220-mm-selftests-2d7d0542face

Best regards,
-- 
Brendan Jackman <jackmanb@google.com>