[PATCH v5 0/5] pids controller events rework

[Michal Koutný]

This makes pids.events:max affine to pids.max limit.

How are the new events supposed to be useful?

- pids.events.local:max
  - tells that cgroup's limit is hit (too tight?)
- pids.events:*
  - "only" directs top-down search to cgroups of interest

Changes from v4 (https://lore.kernel.org/r/20240416142014.27630-1-mkoutny@xxxxxxxx)
- rebased on cgroup/for-6.10 (rather cgroup/for-next, there's no rush)
- introduce pids_files_legacy at one place (Tejun)
- more descriptive Documentation/ (Tejun)

Changes from v3 (https://lore.kernel.org/r/20240405170548.15234-1-mkoutny@xxxxxxxx)
- use existing functions for TAP output in selftest (Muhammad)
- formatting in selftest (Muhammad)
- remove pids.events:max.imposed event, keep it internal (Johannes)
- allow legacy behavior with a mount option
- detach migration charging patches
- drop RFC prefix

Changes from v2 (https://lore.kernel.org/r/20200205134426.10570-1-mkoutny@xxxxxxxx)
- implemented pids.events.local (Tejun)
- added migration charging

[1] https://lore.kernel.org/r/20230202155626.1829121-1-hannes@xxxxxxxxxxx/

Michal Koutný (5):
  cgroup/pids: Separate semantics of pids.events related to pids.max
  cgroup/pids: Make event counters hierarchical
  cgroup/pids: Add pids.events.local
  selftests: cgroup: Lexicographic order in Makefile
  selftests: cgroup: Add basic tests for pids controller

 Documentation/admin-guide/cgroup-v1/pids.rst |   3 +-
 Documentation/admin-guide/cgroup-v2.rst      |  21 ++-
 include/linux/cgroup-defs.h                  |   7 +-
 kernel/cgroup/cgroup.c                       |  15 +-
 kernel/cgroup/pids.c                         | 129 +++++++++++---
 tools/testing/selftests/cgroup/.gitignore    |  11 +-
 tools/testing/selftests/cgroup/Makefile      |  25 +--
 tools/testing/selftests/cgroup/test_pids.c   | 178 +++++++++++++++++++
 8 files changed, 346 insertions(+), 43 deletions(-)
 create mode 100644 tools/testing/selftests/cgroup/test_pids.c


base-commit: 21c38a3bd4ee3fb7337d013a638302fb5e5f9dc2
-- 
2.44.0