[PATCH 0/4] selftests/mm: replace transhuge-stress with a THP compaction selftest

[Sarthak Sharma]

transhuge-stress is a stressor tool that repeatedly
allocates and splits THPs till a specified duration. If the
duration elapses, the test passes and fails only if a setup or
system call fails.

This is not how a test residing in selftests/mm is supposed to
behave. So remove it and add a new functional test called
thp-compaction.c, that allocates THPs as much as it can,
splits those THPs keeping one page retained and discarding
others, and then retries allocating THPs, which will test
if THP compaction is working fine. If we are able to recover
more than half of the initial THPs, the test passes. Otherwise
it fails.

This was suggested by David earlier [1].

Patch 1 removes the current transhuge-stress. Patch 2 adds a check to see
if PFNs are being masked due to no CAP_SYS_ADMIN in the initial user namespace.
Patch 3 factors out THP split helpers from split_huge_page_test.c to vm_util.c.
Patch 4 adds the
new test.

[1] https://lore.kernel.org/all/94ace42d-8d60-4475-953e-74fb3dc23774@xxxxxxxxxx/

Sarthak Sharma (4):
  selftests/mm: remove transhuge-stress
  selftests/mm: detect masked PFNs in allocate_transhuge()
  selftests/mm: factor out THP split helpers
  selftests/mm: add a THP compaction selftest

 MAINTAINERS                                   |   2 +-
 tools/testing/selftests/mm/Makefile           |   2 +-
 tools/testing/selftests/mm/ksm_tests.c        |  26 ++-
 tools/testing/selftests/mm/run_vmtests.sh     |   2 +-
 .../selftests/mm/split_huge_page_test.c       |  45 +---
 tools/testing/selftests/mm/thp-compaction.c   | 215 ++++++++++++++++++
 tools/testing/selftests/mm/transhuge-stress.c | 146 ------------
 tools/testing/selftests/mm/vm_util.c          |  65 ++++++
 tools/testing/selftests/mm/vm_util.h          |   6 +
 9 files changed, 313 insertions(+), 196 deletions(-)
 create mode 100644 tools/testing/selftests/mm/thp-compaction.c
 delete mode 100644 tools/testing/selftests/mm/transhuge-stress.c

-- 
2.53.0