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, DHM cycles each CPU in that partition offline, reconfigures the housekeeping masks (removing the CPU from HK_TYPE_KERNEL_NOISE and related types), and brings it back online. The subsystems (tick/nohz, RCU NOCB, genirq) pick up the new masks through their existing CPU hotplug callbacks. Destroying the partition reverses the cycle: each CPU is taken offline, restored to all housekeeping masks, and brought back online. Housekeeping cpumask pointers are RCU-protected to allow lock-free readers during updates. A global dhm_cycling_cpus mask suppresses transient cpuset partition invalidation while CPUs are being cycled. This work is related to Waiman Long's [PATCH-next 00/23] series ([email protected]), which also targets runtime cpuset housekeeping control. DHM's distinguishing feature is zero-boot- parameter activation: nohz_full+nocb isolation can be achieved at runtime without any boot-time nohz_full= or rcu_nocbs= parameters. Signed-off-by: Jing Wu <[email protected]> Signed-off-by: Qiliang Yuan <[email protected]> --- V3 -> V4: - Drop apply() callback architecture entirely (struct housekeeping_cbs, pre_validate/apply hooks, housekeeping_update_types() notification). Thomas Gleixner identified concurrent in-kernel mask apply as fundamentally unsafe ("broken beyond repair") and endorsed CPU-by-CPU hotplug cycling as the correct approach. - Track A prerequisites (housekeeping boot type isolation, RCU reader protection, cpuset trigger) submitted upstream separately; v4 builds on top of those three committed patches. - Fix rcu/nocb lazy_init: remove __init from rcu_organize_nocb_kthreads() forward declaration (tree.h) to prevent GCC from placing the function in .init.text, which caused an NX-protected page fault when rcu_nocb_cpu_isolate() was called at runtime. Add noinline to rcu_nocb_lazy_init() to preserve the GCC IPA call chain. - Fix cpuset remote partition cycling suppression: extend dhm_cycling_cpus guard to the remote-partition disable path in cpuset_hotplug_update_tasks(), preventing false partition invalidation during hotplug cycling steps. Fixes selftest TEST_MATRIX[69] (A2: expected 1-2, got 1-3). 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. v3: https://lore.kernel.org/r/[email protected] v2: https://lore.kernel.org/r/[email protected] v1: https://lore.kernel.org/all/[email protected] --- Jing Wu (11): sched/isolation: Add runtime housekeeping mask updates with boot snapshots sched/isolation: RCU-protect runtime-mutable housekeeping cpumask readers cgroup/cpuset: Drive kernel-noise housekeeping updates from isolated partitions context_tracking: allow runtime per-CPU user tracking enable/disable rcu/nocb: support lazy init for runtime CPU isolation watchdog: sync watchdog_cpumask with HK_TYPE_KERNEL_NOISE on isolation tick/nohz: add runtime tick_nohz_full_mask update for CPU isolation cpuset: add dhm_cycling_cpus mask to suppress transient invalidation cpuset: drive kernel-noise isolation via per-CPU hotplug cycling 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 | 17 + arch/arm64/kernel/topology.c | 9 +- drivers/base/cpu.c | 20 +- drivers/hv/channel_mgmt.c | 50 +- include/linux/context_tracking.h | 2 + include/linux/nmi.h | 2 + include/linux/rcupdate.h | 2 + include/linux/sched/isolation.h | 32 +- include/linux/tick.h | 4 + kernel/cgroup/cpuset.c | 161 +++++- kernel/context_tracking.c | 38 +- kernel/rcu/tree.h | 2 +- kernel/rcu/tree_nocb.h | 43 +- kernel/sched/core.c | 7 +- kernel/sched/isolation.c | 197 +++++++- kernel/sched/sched.h | 2 +- kernel/time/hrtimer.c | 5 +- kernel/time/tick-sched.c | 47 +- kernel/watchdog.c | 26 +- tools/testing/selftests/cgroup/test_cpuset_prs.sh | 580 +++++++++++++++++++++- 20 files changed, 1181 insertions(+), 65 deletions(-) --- base-commit: eb3f4b7426cfd2b79d65b7d37155480b32259a11 change-id: 20260408-wujing-dhm-8f43e2d49cd8 Best regards, -- Jing Wu <[email protected]>
