Pull cgroup updates from Tejun Heo:

 - cpu.stat now also shows niced CPU time

 - Freezer and cpuset optimizations

 - Other misc changes

* tag 'cgroup-for-6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup/cpuset: Disable cpuset_cpumask_can_shrink() test if not load balancing
  cgroup/cpuset: Further optimize code if CONFIG_CPUSETS_V1 not set
  cgroup/cpuset: Enforce at most one rebuild_sched_domains_locked() call per operation
  cgroup/cpuset: Revert "Allow suppression of sched domain rebuild in update_cpumasks_hier()"
  MAINTAINERS: remove Zefan Li
  cgroup/freezer: Add cgroup CGRP_FROZEN flag update helper
  cgroup/freezer: Reduce redundant traversal for cgroup_freeze
  cgroup/bpf: only cgroup v2 can be attached by bpf programs
  Revert "cgroup: Fix memory leak caused by missing cgroup_bpf_offline"
  selftests/cgroup: Fix compile error in test_cpu.c
  cgroup/rstat: Selftests for niced CPU statistics
  cgroup/rstat: Tracking cgroup-level niced CPU time
  cgroup/cpuset: Fix spelling errors in file kernel/cgroup/cpuset.c

Pull 'struct fd' class updates from Al Viro:
 "The bulk of struct fd memory safety stuff

  Making sure that struct fd instances are destroyed in the same scope
  where they'd been created, getting rid of reassignments and passing
  them by reference, converting to CLASS(fd{,_pos,_raw}).

  We are getting very close to having the memory safety of that stuff
  trivial to verify"

* tag 'pull-fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (28 commits)
  deal with the last remaing boolean uses of fd_file()
  css_set_fork(): switch to CLASS(fd_raw, ...)
  memcg_write_event_control(): switch to CLASS(fd)
  assorted variants of irqfd setup: convert to CLASS(fd)
  do_pollfd(): convert to CLASS(fd)
  convert do_select()
  convert vfs_dedupe_file_range().
  convert cifs_ioctl_copychunk()
  convert media_request_get_by_fd()
  convert spu_run(2)
  switch spufs_calls_{get,put}() to CLASS() use
  convert cachestat(2)
  convert do_preadv()/do_pwritev()
  fdget(), more trivial conversions
  fdget(), trivial conversions
  privcmd_ioeventfd_assign(): don't open-code eventfd_ctx_fdget()
  o2hb_region_dev_store(): avoid goto around fdget()/fdput()
  introduce "fd_pos" class, convert fdget_pos() users to it.
  fdget_raw() users: switch to CLASS(fd_raw)
  convert vmsplice() to CLASS(fd)
  ...

With some recent proposed changes [1] in the deadline server code,
it has caused a test failure in test_cpuset_prs.sh when a change
is being made to an isolated partition. This is due to failing
the cpuset_cpumask_can_shrink() check for SCHED_DEADLINE tasks at
validate_change().

This is actually a false positive as the failed test case involves an
isolated partition with load balancing disabled. The deadline check
is not meaningful in this case and the users should know what they
are doing.

Fix this by doing the cpuset_cpumask_can_shrink() check only when loading
balanced is enabled. Also change its arguments to use effective_cpus
for the current cpuset and user_xcpus() as an approiximation for the
target effective_cpus as the real effective_cpus hasn't been fully
computed yet as this early stage.

As the check isn't comprehensive, there may be false positives or
negatives. We may have to revise the code to do a more thorough check
in the future if this becomes a concern.

[1] https://lore.kernel.org/lkml/82be06c1-6d6d-4651-86c9-bcc828cbcb80@redhat.com/T/#t

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

Currently the cpuset code uses group_subsys_on_dfl() to check if we
are running with cgroup v2. If CONFIG_CPUSETS_V1 isn't set, there is
really no need to do this check and we can optimize out some of the
unneeded v1 specific code paths. Introduce a new cpuset_v2() and use it
to replace the cgroup_subsys_on_dfl() check to further optimize the
code.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

Since commit ff0ce721ec21 ("cgroup/cpuset: Eliminate unncessary
sched domains rebuilds in hotplug"), there is only one
rebuild_sched_domains_locked() call per hotplug operation. However,
writing to the various cpuset control files may still casue more than
one rebuild_sched_domains_locked() call to happen in some cases.

Juri had found that two rebuild_sched_domains_locked() calls in
update_prstate(), one from update_cpumasks_hier() and another one from
update_partition_sd_lb() could cause cpuset partition to be created
with null total_bw for DL tasks. IOW, DL tasks may not be scheduled
correctly in such a partition.

A sample command sequence that can reproduce null total_bw is as
follows.

  # echo Y >/sys/kernel/debug/sched/verbose
  # echo +cpuset >/sys/fs/cgroup/cgroup.subtree_control
  # mkdir /sys/fs/cgroup/test
  # echo 0-7 > /sys/fs/cgroup/test/cpuset.cpus
  # echo 6-7 > /sys/fs/cgroup/test/cpuset.cpus.exclusive
  # echo root >/sys/fs/cgroup/test/cpuset.cpus.partition

Fix this double rebuild_sched_domains_locked() calls problem
by replacing existing calls with cpuset_force_rebuild() except
the rebuild_sched_domains_cpuslocked() call at the end of
cpuset_handle_hotplug(). Checking of the force_sd_rebuild flag is
now done at the end of cpuset_write_resmask() and update_prstate()
to determine if rebuild_sched_domains_locked() should be called or not.

The cpuset v1 code can still call rebuild_sched_domains_locked()
directly as double rebuild_sched_domains_locked() calls is not possible.

Reported-by: Juri Lelli <juri.lelli@redhat.com>
Closes: https://lore.kernel.org/lkml/ZyuUcJDPBln1BK1Y@jlelli-thinkpadt14gen4.remote.csb/
Signed-off-by: Waiman Long <longman@redhat.com>
Tested-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

Revert commit 3ae0b773211e ("cgroup/cpuset: Allow suppression of sched
domain rebuild in update_cpumasks_hier()") to allow for an alternative
way to suppress unnecessary rebuild_sched_domains_locked() calls in
update_cpumasks_hier() and elsewhere in a following commit.

Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

reference acquired there by fget_raw() is not stashed anywhere -
we could as well borrow instead.

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Add help to update cgroup CGRP_FROZEN flag. Both cgroup_propagate_frozen
and cgroup_update_frozen functions update CGRP_FROZEN flag, this makes
code concise.

Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

Whether a cgroup is frozen is determined solely by whether it is set to
to be frozen and whether its parent is frozen. Currently, when is cgroup
is frozen or unfrozen, it iterates through the entire subtree to freeze
or unfreeze its descentdants. However, this is unesessary for a cgroup
that does not change its effective frozen status. This path aims to skip
the subtree if its parent does not have a change in effective freeze.

For an example, subtree like, a-b-c-d-e-f-g, when a is frozen, the
entire tree is frozen. If we freeze b and c again, it is unesessary to
iterate d, e, f and g. So does that If we unfreeze b/c.

Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>