[PATCH v6 0/8] cgroup/cpuset: Fix partition related locking issues

[Waiman Long <longman@redhat.com>]

 v6:
  - Rebase on top of the latest v7.0 pre-RC linux tree.
  - Add another fix patch to fix found during code inspection.
  - Revert back to the v4 idea of just deferring the housekeeping_update()
    call to workqueue to make it simple as v5 change will add quite a
    bit more complexity to the cpuset code.

 v5:
  - https://lore.kernel.org/lkml/20260212164640.2408295-1-longman@redhat.com/

After booting the latest linux debug kernel with the latest cgroup
changes as well as Federic's "cpuset/isolation: Honour kthreads
preferred affinity" patch series [1] merged on top and running the
test-cpuset-prs.sh test, a circular locking dependency lockdep splat
was reported. See patch 5 for details.

To fix this issue, the cpuset code is modified to not call
housekeeping_update() with cpu_hotplug_lock held.  The cpuset hotplug
code is also modified to defer the housekeeping_update() call, if needed,
to workqueue.  A new top level cpuset_top_mutex is added to have more
exclusion control.

With these changes in place, the cpuset test ran to completion with no
failure and no lockdep splat.

[1] https://lore.kernel.org/lkml/20260125224541.50226-1-frederic@kernel.org/

Waiman Long (8):
  cgroup/cpuset: Fix incorrect change to effective_xcpus in
    partition_xcpus_del()
  cgroup/cpuset: Fix incorrect use of cpuset_update_tasks_cpumask() in
    update_cpumasks_hier()
  cgroup/cpuset: Clarify exclusion rules for cpuset internal variables
  cgroup/cpuset: Set isolated_cpus_updating only if isolated_cpus is
    changed
  kselftest/cgroup: Simplify test_cpuset_prs.sh by removing "S+" command
  cgroup/cpuset: Move housekeeping_update()/rebuild_sched_domains()
    together
  cgroup/cpuset: Defer housekeeping_update() calls from CPU hotplug to
    workqueue
  cgroup/cpuset: Call housekeeping_update() without holding
    cpus_read_lock

 kernel/cgroup/cpuset.c                        | 220 +++++++++++------
 kernel/sched/isolation.c                      |   4 +-
 kernel/time/timer_migration.c                 |   4 +-
 .../selftests/cgroup/test_cpuset_prs.sh       | 225 +++++++++---------
 4 files changed, 265 insertions(+), 188 deletions(-)

-- 
2.53.0