[tip: sched/core] kthread: Switch to cpu_possible_mask

[tip-bot2 for Marcelo Tosatti]

The following commit has been merged into the sched/core branch of tip:

Commit-ID:     043eb8e1051143a24811e6f35c276e35ae8247b6
Gitweb:        https://git.kernel.org/tip/043eb8e1051143a24811e6f35c276e35ae8247b6
Author:        Marcelo Tosatti <mtosatti@xxxxxxxxxx>
AuthorDate:    Wed, 27 May 2020 16:29:08 +02:00
Committer:     Peter Zijlstra <peterz@xxxxxxxxxxxxx>
CommitterDate: Mon, 15 Jun 2020 14:10:03 +02:00

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@xxxxxxxxxx>
Signed-off-by: Frederic Weisbecker <frederic@xxxxxxxxxx>
Signed-off-by: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Link: https://lkml.kernel.org/r/20200527142909.23372-2-frederic@xxxxxxxxxx
---
 kernel/kthread.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/kthread.c b/kernel/kthread.c
index 8e3d2d7..b86d37c 100644
--- a/kernel/kthread.c
+++ b/kernel/kthread.c
@@ -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;