create_worker() will already set the right affinity using kthread_bind_mask(), this means only the rescuer will need to change it's affinity.
Howveer, while in cpu-hot-unplug a regular task is not allowed to run on online&&!active as it would be pushed away quite agressively. We need KTHREAD_IS_PER_CPU to survive in that environment. Therefore set the affinity after getting that magic flag. Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> --- kernel/workqueue.c | 9 +++------ 1 file changed, 3 insertions(+), 6 deletions(-) --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -1849,12 +1849,6 @@ static void worker_attach_to_pool(struct mutex_lock(&wq_pool_attach_mutex); /* - * set_cpus_allowed_ptr() will fail if the cpumask doesn't have any - * online CPUs. It'll be re-applied when any of the CPUs come up. - */ - set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); - - /* * The wq_pool_attach_mutex ensures %POOL_DISASSOCIATED remains * stable across this function. See the comments above the flag * definition for details. @@ -1864,6 +1858,9 @@ static void worker_attach_to_pool(struct else kthread_set_per_cpu(worker->task, pool->cpu); + if (worker->rescue_wq) + set_cpus_allowed_ptr(worker->task, pool->attrs->cpumask); + list_add_tail(&worker->node, &pool->workers); worker->pool = pool;