From 885b3ba47aa5cc16550beb8a42181ad5e8302ceb Mon Sep 17 00:00:00 2001 From: Valentin Schneider Date: Tue, 13 Oct 2020 15:01:15 +0100 Subject: [PATCH] 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 Signed-off-by: Peter Zijlstra (Intel) Link: https://lkml.kernel.org/r/20201013140116.26651-1-valentin.schneider@arm.com --- kernel/sched/core.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index e92d7853057c..88c6fcb3bb65 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -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 -- 2.11.0