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

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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
This commit is contained in:
Valentin Schneider 2020-10-13 15:01:15 +01:00 committed by Peter Zijlstra
parent 86fbcd3b4b
commit 885b3ba47a
1 changed files with 11 additions and 2 deletions
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13
kernel/sched/core.c
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@ -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))
goto out;
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