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kernel/workqueue: Let rescuers follow unbound wq cpumask changes 

When workqueue cpumask changes are committed the associated rescuer (if
one exists) affinity is not touched and this might be a problem down the
line for isolated setups.

Make sure rescuers affinity is updated every time a workqueue cpumask
changes, so that rescuers can't break isolation.

 [longman: set_cpus_allowed_ptr() will block until the designated task
  is enqueued on an allowed CPU, no wake_up_process() needed. Also use
  the unbound_effective_cpumask() helper as suggested by Tejun.]

Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Juri Lelli 2024-02-08 11:10:13 -05:00 committed by Tejun Heo
parent 4c065dbce1
commit d64f2fa064
1 changed files with 5 additions and 0 deletions
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5
kernel/workqueue.c
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@ -5051,6 +5051,11 @@ static void apply_wqattrs_commit(struct apply_wqattrs_ctx *ctx)
/* update node_nr_active->max */
wq_update_node_max_active(ctx->wq, -1);
/* rescuer needs to respect wq cpumask changes */
if (ctx->wq->rescuer)
set_cpus_allowed_ptr(ctx->wq->rescuer->task,
unbound_effective_cpumask(ctx->wq));
mutex_unlock(&ctx->wq->mutex);
}