[PATCH v3 00/13] Dynamic Housekeeping Management (DHM) via CPUSets

[Jing Wu <realwujing@gmail.com>]

This series introduces Dynamic Housekeeping Management (DHM) to the Linux
kernel, enabling runtime reconfiguration of kernel-noise housekeeping
(nohz_full tick suppression, RCU NOCB offloading, and managed IRQ
migration) through the existing cgroup v2 cpuset isolated partition
mechanism — no new kernel ABI required.

When a cpuset partition is set to isolated mode, the CPUs in that
partition are removed from the kernel's global housekeeping masks.  The
housekeeping subsystems (tick/nohz, RCU NOCB, genirq) react via explicit
registered callbacks, applying the new masks at runtime.  Destroying the
partition restores the CPUs to all housekeeping masks.

The architecture uses a per-type callback table (struct housekeeping_cbs)
with pre_validate/apply hooks, replacing the previous notifier chain.
Housekeeping cpumask pointers are RCU-protected to allow lock-free readers
during updates.

Signed-off-by: Jing Wu <realwujing@gmail.com>
Signed-off-by: Qiliang Yuan <yuanql9@chinatelecom.cn>
---
V2 -> V3:
- Replace notifier chain with explicit per-type callback interface
  (struct housekeeping_cbs with .name, .pre_validate, .apply fields).
- RCU-protect all housekeeping cpumask pointers; callers must hold
  rcu_read_lock() or use housekeeping_cpumask_rcu() in apply() callbacks.
- Drop 5 patches from v2: HK_TYPE enum separation (upstream aliases are
  already correct), no-op timer/hrtimer patches, kthread dead code, and
  workqueue double-update.
- Fix deadlock in rcu_hk_workfn(): remove cpus_read_lock() wrapper around
  remove_cpu()/add_cpu() which take cpu_hotplug_lock write side.
- Fix UAF in rcu_hk_apply(): snapshot the housekeeping cpumask inside the
  work function under rcu_read_lock(), not at apply() time where the old
  pointer may be freed by synchronize_rcu() before the work runs.
- Fix tick apply(): snapshot housekeeping_cpumask_rcu() under
  rcu_read_lock() as required by lockdep for runtime-mutable types.
- Activate context_tracking dynamically via ct_cpu_track_user() /
  ct_cpu_untrack_user() in tick apply(), eliminating the dependency on
  CONFIG_CONTEXT_TRACKING_USER_FORCE flagged by tglx.
- Fix genirq apply(): snapshot HK_TYPE_MANAGED_IRQ mask under
  rcu_read_lock() before the IRQ iteration loop.
- Simplify cpuset noise_types to BIT(HK_TYPE_KERNEL_NOISE) |
  BIT(HK_TYPE_MANAGED_IRQ), replacing the redundant per-alias bitmask.
- housekeeping_update_types(): always use cpu_possible_mask as base
  for HK_TYPE_KERNEL_NOISE, so de-isolation restores the mask to all
  possible CPUs rather than leaving it at its last non-trivial value.
- Initialize watchdog_cpumask from HK_TYPE_KERNEL_NOISE (not
  HK_TYPE_TIMER) at boot; keep it in sync at runtime via a new
  housekeeping_cbs callback.
- Add kernel-noise selftest to test_cpuset_prs.sh, including
  cpu_in_cpulist() for correct cpulist range membership detection and
  nohz_full sysfs verification when CONFIG_NO_HZ_FULL is active.
- Add RCU caller fixes: sched/core (HK_TYPE_KERNEL_NOISE) and
  drivers/hv (HK_TYPE_MANAGED_IRQ) are required because those types
  are updated at runtime; hrtimer (HK_TYPE_TIMER) and arm64/topology
  (HK_TYPE_TICK) are defensive fixes.
- Reorder patches so all subsystem callbacks are registered before the
  cpuset patch that triggers housekeeping_update_types().

V1 -> V2:
- Rebrand series from DHEI to DHM (Dynamic Housekeeping Management).
- Drop custom sysfs interface entirely.
- Integrate housekeeping control into cgroup v2 cpuset isolated partition
  mechanism.
- Add SMT-aware isolation constraints to prevent splitting SMT siblings.
- Add comprehensive documentation and cgroup functional selftests.
- Refactor mask transition logic to use RCU-safe handover.

v2: https://lore.kernel.org/r/20260413-wujing-dhm-v2-0-06df21caba5d@gmail.com
v1: https://lore.kernel.org/all/20260325-dhei-v12-final-v1-0-919cca23cadf@gmail.com

---
Jing Wu (13):
      sched/isolation: Replace notifier chain with explicit callback interface
      sched/isolation: Add housekeeping_update_types() for kernel-noise masks
      sched/isolation: RCU-protect all housekeeping cpumask readers
      sched/isolation: Fix RCU protection for runtime-mutable cpumask callers
      cpu/hotplug: Reserve CPUHP states for nohz_full and managed IRQ down-paths
      tick/nohz, context_tracking: Prepare for runtime nohz_full updates
      rcu/nocb: Add explicit housekeeping callback for runtime NOCB toggling
      genirq: Add explicit housekeeping callback for managed IRQ migration
      watchdog/lockup_detector: Register housekeeping callback for kernel-noise
      sched: Guard sched_tick_start/stop against uninitialized tick_work_cpu
      cgroup/cpuset: Extend isolated partition to trigger kernel-noise isolation
      docs: cgroup-v2: Document kernel-noise isolation via isolated partitions
      selftests/cgroup: Add kernel-noise isolation test to cpuset selftest

 Documentation/admin-guide/cgroup-v2.rst           |   8 +
 arch/arm64/kernel/topology.c                      |   9 +-
 drivers/hv/channel_mgmt.c                         |  50 +++--
 include/linux/context_tracking.h                  |   1 +
 include/linux/cpuhotplug.h                        |   2 +
 include/linux/sched/isolation.h                   |  41 ++++
 kernel/cgroup/cpuset.c                            |  23 +-
 kernel/context_tracking.c                         |  23 +-
 kernel/irq/manage.c                               |  86 ++++++++
 kernel/rcu/tree.c                                 | 104 +++++++++
 kernel/sched/core.c                               |   7 +-
 kernel/sched/isolation.c                          | 256 ++++++++++++++++++++--
 kernel/time/hrtimer.c                             |   5 +-
 kernel/time/tick-sched.c                          | 157 ++++++++++++-
 kernel/watchdog.c                                 |  56 ++++-
 tools/testing/selftests/cgroup/test_cpuset_prs.sh | 204 ++++++++++++++++-
 16 files changed, 968 insertions(+), 64 deletions(-)
---
base-commit: eb3f4b7426cfd2b79d65b7d37155480b32259a11
change-id: 20260408-wujing-dhm-8f43e2d49cd8

Best regards,
-- 
Jing Wu <realwujing@gmail.com>