[PATCH v6] mm, memcg: cg2 memory{.swap,}.peak write handlers

[David Finkel <davidf@vimeo.com>]

This is an updated patchset rebasing onto -torvalds master (post
6.11-rc1), and addressing comments from Michal and Tejun.

As requested by Tejun and Johannes, I've removed the explicit check for
the string "reset", so it now allows any non-empty string. (Empty
strings get filtered before our write handler executes)

I've also made several of the field reads and writes atomic with
{READ,WRITE}_ONCE, and adjusted more of the types to be unsigned.

Documentation/admin-guide/cgroup-v2.rst          |  22 ++--
include/linux/cgroup-defs.h                      |   5 +
include/linux/cgroup.h                           |   3 +
include/linux/memcontrol.h                       |   5 +
include/linux/page_counter.h                     |  11 +-
kernel/cgroup/cgroup-internal.h                  |   2 +
kernel/cgroup/cgroup.c                           |   7 +
mm/memcontrol.c                                  | 116 +++++++++++++++--
mm/page_counter.c                                |  30 +++--
tools/testing/selftests/cgroup/cgroup_util.c     |  22 ++++
tools/testing/selftests/cgroup/cgroup_util.h     |   2 +
tools/testing/selftests/cgroup/test_memcontrol.c | 229 +++++++++++++++++++++++++++++++--
12 files changed, 419 insertions(+), 35 deletions(-)

[1]: https://lore.kernel.org/cgroups/20240724161942.3448841-3-davidf@vimeo.com/T/