Commit 885b3ba4 authored Oct 13, 2020 by Valentin Schneider Committed by Peter Zijlstra Nov 10, 2020

sched: Deny self-issued __set_cpus_allowed_ptr() when migrate_disable()



  migrate_disable();
  set_cpus_allowed_ptr(current, {something excluding task_cpu(current)});
  affine_move_task(); <-- never returns

Signed-off-by: Valentin Schneider <valentin.schneider@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20201013140116.26651-1-valentin.schneider@arm.com

parent 86fbcd3b

kernel/sched/core.c

+11 −2

Original line number	Diff line number	Diff line
		@@ -2238,8 +2238,17 @@ static int __set_cpus_allowed_ptr(struct task_struct *p,
		goto out;
		}

		if (!(flags & SCA_MIGRATE_ENABLE) && cpumask_equal(&p->cpus_mask, new_mask))
		if (!(flags & SCA_MIGRATE_ENABLE)) {
		if (cpumask_equal(&p->cpus_mask, new_mask))
		goto out;

		if (WARN_ON_ONCE(p == current &&
		is_migration_disabled(p) &&
		!cpumask_test_cpu(task_cpu(p), new_mask))) {
		ret = -EBUSY;
		goto out;
		}
		}

		/*
		* Picking a ~random cpu helps in cases where we are changing affinity