kthread: Switch to cpu_possible_mask (043eb8e1) · Commits · 戴 / test

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:

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

kernel/kthread.c

+2 −2

Original line number	Original line	Diff line number	Diff line
	@@ -383,7 +383,7 @@ struct task_struct __kthread_create_on_node(int (threadfn)(void *data),
	* The kernel thread should not inherit these properties.		* The kernel thread should not inherit these properties.
	*/		*/
	sched_setscheduler_nocheck(task, SCHED_NORMAL, &param);		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);		kfree(create);
	return task;		return task;
	@@ -608,7 +608,7 @@ int kthreadd(void *unused)
	/* Setup a clean context for our children to inherit. */		/* Setup a clean context for our children to inherit. */
	set_task_comm(tsk, "kthreadd");		set_task_comm(tsk, "kthreadd");
	ignore_signals(tsk);		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]);		set_mems_allowed(node_states[N_MEMORY]);

	current->flags \|= PF_NOFREEZE;		current->flags \|= PF_NOFREEZE;

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