Merge tag 'kthread-for-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks

Pull kthread updates from Frederic Weisbecker:
 "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"

* tag 'kthread-for-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks: (33 commits)
  doc: Add housekeeping documentation
  kthread: Document kthread_affine_preferred()
  kthread: Comment on the purpose and placement of kthread_affine_node() call
  kthread: Honour kthreads preferred affinity after cpuset changes
  sched/arm64: Move fallback task cpumask to HK_TYPE_DOMAIN
  sched: Switch the fallback task allowed cpumask to HK_TYPE_DOMAIN
  kthread: Rely on HK_TYPE_DOMAIN for preferred affinity management
  kthread: Include kthreadd to the managed affinity list
  kthread: Include unbound kthreads in the managed affinity list
  kthread: Refine naming of affinity related fields
  PCI: Remove superfluous HK_TYPE_WQ check
  sched/isolation: Remove HK_TYPE_TICK test from cpu_is_isolated()
  cpuset: Remove cpuset_cpu_is_isolated()
  timers/migration: Remove superfluous cpuset isolation test
  cpuset: Propagate cpuset isolation update to timers through housekeeping
  cpuset: Propagate cpuset isolation update to workqueue through housekeeping
  PCI: Flush PCI probe workqueue on cpuset isolated partition change
  sched/isolation: Flush vmstat workqueues on cpuset isolated partition change
  sched/isolation: Flush memcg workqueues on cpuset isolated partition change
  cpuset: Update HK_TYPE_DOMAIN cpumask from cpuset
  ...

1 files changed, 10 insertions, 7 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 253311af47c6..eb5660013222 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -6959,13 +6959,16 @@ static int workqueue_apply_unbound_cpumask(const cpumask_var_t unbound_cpumask)
 }
 
 /**
- * workqueue_unbound_exclude_cpumask - Exclude given CPUs from unbound cpumask
- * @exclude_cpumask: the cpumask to be excluded from wq_unbound_cpumask
+ * workqueue_unbound_housekeeping_update - Propagate housekeeping cpumask update
+ * @hk: the new housekeeping cpumask
  *
- * This function can be called from cpuset code to provide a set of isolated
- * CPUs that should be excluded from wq_unbound_cpumask.
+ * Update the unbound workqueue cpumask on top of the new housekeeping cpumask such
+ * that the effective unbound affinity is the intersection of the new housekeeping
+ * with the requested affinity set via nohz_full=/isolcpus= or sysfs.
+ *
+ * Return: 0 on success and -errno on failure.
  */
-int workqueue_unbound_exclude_cpumask(cpumask_var_t exclude_cpumask)
+int workqueue_unbound_housekeeping_update(const struct cpumask *hk)
 {
 	cpumask_var_t cpumask;
 	int ret = 0;
@@ -6981,14 +6984,14 @@ int workqueue_unbound_exclude_cpumask(cpumask_var_t exclude_cpumask)
 	 * (HK_TYPE_WQ ∩ HK_TYPE_DOMAIN) house keeping mask and rewritten
 	 * by any subsequent write to workqueue/cpumask sysfs file.
 	 */
-	if (!cpumask_andnot(cpumask, wq_requested_unbound_cpumask, exclude_cpumask))
+	if (!cpumask_and(cpumask, wq_requested_unbound_cpumask, hk))
 		cpumask_copy(cpumask, wq_requested_unbound_cpumask);
 	if (!cpumask_equal(cpumask, wq_unbound_cpumask))
 		ret = workqueue_apply_unbound_cpumask(cpumask);
 
 	/* Save the current isolated cpumask & export it via sysfs */
 	if (!ret)
-		cpumask_copy(wq_isolated_cpumask, exclude_cpumask);
+		cpumask_andnot(wq_isolated_cpumask, cpu_possible_mask, hk);
 
 	mutex_unlock(&wq_pool_mutex);
 	free_cpumask_var(cpumask);