[GIT PULL] Kthread changes for v7.0

[Frederic Weisbecker <frederic@kernel.org>]

Hello Linus,

Once the merge window opens, please pull the following changes since
commit 9448598b22c50c8a5bb77a9103e2d49f134c9578:

  Linux 6.19-rc2 (2025-12-21 15:52:04 -0800)

are available in the Git repository at:

  https://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git tags/kthread-for-7.0

for you to fetch changes up to fa39ec4f89f2637ed1cdbcde3656825951787668:

  doc: Add housekeeping documentation (2026-02-03 15:23:35 +0100)

----------------------------------------------------------------
The kthread code provides an infrastructure which manages the preferred
affinity of unbound kthreads (node or custom cpumask) against
housekeeping (CPU isolation) constraints and CPU hotplug events.

One crucial missing piece is the handling of cpuset: when an isolated
partition is created, deleted, or its CPUs updated, all the unbound
kthreads in the top cpuset become indifferently affine to _all_ the
non-isolated CPUs, possibly breaking their preferred affinity along
the way.

Solve this with performing the kthreads affinity update from cpuset to
the kthreads consolidated relevant code instead so that preferred
affinities are honoured and applied against the updated cpuset isolated
partitions.

The dispatch of the new isolated cpumasks to timers, workqueues and
kthreads is performed by housekeeping, as per the nice Tejun's
suggestion.

As a welcome side effect, HK_TYPE_DOMAIN then integrates both the set
from boot defined domain isolation (through isolcpus=) and cpuset
isolated partitions. Housekeeping cpumasks are now modifiable with a
specific RCU based synchronization. A big step toward making nohz_full=
also mutable through cpuset in the future.

Thanks!

----------------------------------------------------------------
Frederic Weisbecker (33):
      PCI: Prepare to protect against concurrent isolated cpuset change
      cpu: Revert "cpu/hotplug: Prevent self deadlock on CPU hot-unplug"
      memcg: Prepare to protect against concurrent isolated cpuset change
      mm: vmstat: Prepare to protect against concurrent isolated cpuset change
      sched/isolation: Save boot defined domain flags
      cpuset: Convert boot_hk_cpus to use HK_TYPE_DOMAIN_BOOT
      driver core: cpu: Convert /sys/devices/system/cpu/isolated to use HK_TYPE_DOMAIN_BOOT
      net: Keep ignoring isolated cpuset change
      block: Protect against concurrent isolated cpuset change
      timers/migration: Prevent from lockdep false positive warning
      cpu: Provide lockdep check for CPU hotplug lock write-held
      cpuset: Provide lockdep check for cpuset lock held
      sched/isolation: Convert housekeeping cpumasks to rcu pointers
      cpuset: Update HK_TYPE_DOMAIN cpumask from cpuset
      sched/isolation: Flush memcg workqueues on cpuset isolated partition change
      sched/isolation: Flush vmstat workqueues on cpuset isolated partition change
      PCI: Flush PCI probe workqueue on cpuset isolated partition change
      cpuset: Propagate cpuset isolation update to workqueue through housekeeping
      cpuset: Propagate cpuset isolation update to timers through housekeeping
      timers/migration: Remove superfluous cpuset isolation test
      cpuset: Remove cpuset_cpu_is_isolated()
      sched/isolation: Remove HK_TYPE_TICK test from cpu_is_isolated()
      PCI: Remove superfluous HK_TYPE_WQ check
      kthread: Refine naming of affinity related fields
      kthread: Include unbound kthreads in the managed affinity list
      kthread: Include kthreadd to the managed affinity list
      kthread: Rely on HK_TYPE_DOMAIN for preferred affinity management
      sched: Switch the fallback task allowed cpumask to HK_TYPE_DOMAIN
      sched/arm64: Move fallback task cpumask to HK_TYPE_DOMAIN
      kthread: Honour kthreads preferred affinity after cpuset changes
      kthread: Comment on the purpose and placement of kthread_affine_node() call
      kthread: Document kthread_affine_preferred()
      doc: Add housekeeping documentation

 Documentation/arch/arm64/asymmetric-32bit.rst |  12 +-
 Documentation/core-api/housekeeping.rst       | 111 ++++++++++++++++++
 Documentation/core-api/index.rst              |   1 +
 arch/arm64/kernel/cpufeature.c                |   6 +-
 block/blk-mq.c                                |   6 +-
 drivers/base/cpu.c                            |   2 +-
 drivers/pci/pci-driver.c                      |  71 +++++++++---
 include/linux/cpuhplock.h                     |   1 +
 include/linux/cpuset.h                        |   8 +-
 include/linux/kthread.h                       |   1 +
 include/linux/memcontrol.h                    |   4 +
 include/linux/mmu_context.h                   |   2 +-
 include/linux/pci.h                           |   3 +
 include/linux/percpu-rwsem.h                  |   1 +
 include/linux/sched/isolation.h               |  16 ++-
 include/linux/vmstat.h                        |   2 +
 include/linux/workqueue.h                     |   2 +-
 init/Kconfig                                  |   1 +
 kernel/cgroup/cpuset.c                        |  53 +++------
 kernel/cpu.c                                  |  42 +++----
 kernel/kthread.c                              | 160 +++++++++++++++++---------
 kernel/sched/isolation.c                      | 145 ++++++++++++++++++-----
 kernel/sched/sched.h                          |   4 +
 kernel/time/timer_migration.c                 |  25 ++--
 kernel/workqueue.c                            |  17 +--
 mm/memcontrol.c                               |  31 ++++-
 mm/vmstat.c                                   |  15 ++-
 net/core/net-sysfs.c                          |   2 +-
 28 files changed, 538 insertions(+), 206 deletions(-)
 create mode 100644 Documentation/core-api/housekeeping.rst