Currently, when pids.max limit is breached in the hierarchy, the event
is counted and reported in the cgroup where the forking task resides. This
isn't hierarchical neither binds event to its limit

Reasons for RFC:

1) Introduction of new event type.

2) Missing one step further would be to distinguish pids.events and
   pids.events.local.

Changes from v1:  https://lkml.kernel.org/r/20191128172612.10259-1-mkoutny-IBi9RG/b67k@public.gmane.org
- introduce two separate types of events
- make event counting hierarchical

Michal Koutn√Ω (3):
  cgroup/pids: Separate semantics of pids.events related to pids.max
  cgroup/pids: Make event counters hierarchical
  selftests: cgroup: Add basic tests for pids controller

 Documentation/admin-guide/cgroup-v1/pids.rst |   3 +-
 Documentation/admin-guide/cgroup-v2.rst      |  14 ++
 kernel/cgroup/pids.c                         |  92 +++++++--
 tools/testing/selftests/cgroup/Makefile      |   8 +-
 tools/testing/selftests/cgroup/test_pids.c   | 188 +++++++++++++++++++
 5 files changed, 288 insertions(+), 17 deletions(-)
 create mode 100644 tools/testing/selftests/cgroup/test_pids.c

-- 
2.24.1