By the time scx_sched_free_rcu_work() runs, the scx_sched is no longer
reachable. However, a previously queued error_irq_work may still be pending or
running. Ensure it completes before proceeding with teardown.

Fixes: bff3b5aec1b7 ("sched_ext: Move disable machinery into scx_sched")
Signed-off-by: Tejun Heo <tj@kernel.org>
---
 kernel/sched/ext.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
index XXXXXXXX..XXXXXXXX 100644
--- a/kernel/sched/ext.c
+++ b/kernel/sched/ext.c
@@ -3471,7 +3471,9 @@ static void scx_sched_free_rcu_work(struct rcu_work *rwork)
 	struct scx_dispatch_q *dsq;
 	int node;

+	irq_work_sync(&sch->error_irq_work);
 	kthread_stop(sch->helper->task);
+
 	free_percpu(sch->pcpu);

 	for_each_node_state(node, N_POSSIBLE)
--
2.48.0

On Thu, Oct 09, 2025 at 01:56:23PM -1000, Tejun Heo wrote:
> By the time scx_sched_free_rcu_work() runs, the scx_sched is no longer
> reachable. However, a previously queued error_irq_work may still be pending or
> running. Ensure it completes before proceeding with teardown.
> 
> Fixes: bff3b5aec1b7 ("sched_ext: Move disable machinery into scx_sched")
> Signed-off-by: Tejun Heo <tj@kernel.org>

Applied to sched_ext/for-6.18-fixes.

Thanks.

-- 
tejun

On Thu, Oct 09, 2025 at 01:56:23PM -1000, Tejun Heo wrote:
> By the time scx_sched_free_rcu_work() runs, the scx_sched is no longer
> reachable. However, a previously queued error_irq_work may still be pending or
> running. Ensure it completes before proceeding with teardown.
> 
> Fixes: bff3b5aec1b7 ("sched_ext: Move disable machinery into scx_sched")
> Signed-off-by: Tejun Heo <tj@kernel.org>

Good catch.

Acked-by: Andrea Righi <arighi@nvidia.com>

Thanks,
-Andrea

> ---
>  kernel/sched/ext.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/kernel/sched/ext.c b/kernel/sched/ext.c
> index XXXXXXXX..XXXXXXXX 100644
> --- a/kernel/sched/ext.c
> +++ b/kernel/sched/ext.c
> @@ -3471,7 +3471,9 @@ static void scx_sched_free_rcu_work(struct rcu_work *rwork)
>  	struct scx_dispatch_q *dsq;
>  	int node;
> 
> +	irq_work_sync(&sch->error_irq_work);
>  	kthread_stop(sch->helper->task);
> +
>  	free_percpu(sch->pcpu);
> 
>  	for_each_node_state(node, N_POSSIBLE)
> --
> 2.48.0