[PATCH/for-next v2 0/2] cgroup/cpuset: Fix partition related locking issues

[Waiman Long <longman@redhat.com>]

 v2:
  - Change patch 1 to use workqueue instead of task run as it is a
    per-cpu kthread that performs the cpuset shutdown and bringup work.
  - Simplify and streamline some of the code.

After booting the latest cgroup for-next 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 2 for details.

The following changes are made to resolve this locking problem.
 1) Deferring calling housekeeping_update() from CPU hotplug to workqueue
 2) Release cpus_read_lock before calling housekeeping_update()

With these changes, 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 (2):
  cgroup/cpuset: Defer housekeeping_update() call from CPU hotplug to
    workqueue
  cgroup/cpuset: Introduce a new top level cpuset_top_mutex

 kernel/cgroup/cpuset.c                        | 124 ++++++++++++++----
 kernel/sched/isolation.c                      |   4 +-
 kernel/time/timer_migration.c                 |   3 +-
 .../selftests/cgroup/test_cpuset_prs.sh       |  13 +-
 4 files changed, 107 insertions(+), 37 deletions(-)

-- 
2.52.0