kthread: Switch to cpu_possible_mask

Next patch will switch unbound kernel threads mask to
housekeeping_cpumask(), a subset of cpu_possible_mask. So in order to
ease bisection, lets first switch kthreads default affinity from
cpu_all_mask to cpu_possible_mask.

It looks safe to do so as cpu_possible_mask seem to be initialized
at setup_arch() time, way before kthreadd is created.

Suggested-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20200527142909.23372-2-frederic@kernel.org
This commit is contained in:
Marcelo Tosatti 2020-05-27 16:29:08 +02:00 committed by Peter Zijlstra
parent 461daba06b
commit 043eb8e105

View file

@ -383,7 +383,7 @@ struct task_struct *__kthread_create_on_node(int (*threadfn)(void *data),
* The kernel thread should not inherit these properties.
*/
sched_setscheduler_nocheck(task, SCHED_NORMAL, &param);
set_cpus_allowed_ptr(task, cpu_all_mask);
set_cpus_allowed_ptr(task, cpu_possible_mask);
}
kfree(create);
return task;
@ -608,7 +608,7 @@ int kthreadd(void *unused)
/* Setup a clean context for our children to inherit. */
set_task_comm(tsk, "kthreadd");
ignore_signals(tsk);
set_cpus_allowed_ptr(tsk, cpu_all_mask);
set_cpus_allowed_ptr(tsk, cpu_possible_mask);
set_mems_allowed(node_states[N_MEMORY]);
current->flags |= PF_NOFREEZE;