[PATCH wq/for-6.9 v4 4/4] workqueue: Bind unbound workqueue rescuer to wq_unbound_cpumask

Waiman Long
2024-02-07T01:19:37Z

Commit 85f0ab43f9de ("kernel/workqueue: Bind rescuer to unbound
cpumask for WQ_UNBOUND") modified init_rescuer() to bind rescuer of
an unbound workqueue to the cpumask in wq->unbound_attrs. However
unbound_attrs->cpumask's of all workqueues are initialized to
cpu_possible_mask and will only be changed if it has the WQ_SYSFS flag
to expose a cpumask sysfs file to be written by users. So this patch
doesn't achieve what it is intended to do.

If an unbound workqueue is created after wq_unbound_cpumask is modified
and there is no more unbound cpumask update after that, the unbound
rescuer will be bound to all CPUs unless the workqueue is created
with the WQ_SYSFS flag and a user explicitly modified its cpumask
sysfs file. Fix this problem by binding directly to wq_unbound_cpumask
in init_rescuer().

Fixes: 85f0ab43f9de ("kernel/workqueue: Bind rescuer to unbound cpumask for WQ_UNBOUND")
Signed-off-by: Waiman Long <longman@redhat.com>
---
kernel/workqueue.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 3044ad6f9496..81800cc2ee28 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -5332,7 +5332,7 @@ static int init_rescuer(struct workqueue_struct *wq)

wq->rescuer = rescuer;
if (wq->flags & WQ_UNBOUND)
- kthread_bind_mask(rescuer->task, wq->unbound_attrs->cpumask);
+ kthread_bind_mask(rescuer->task, wq_unbound_cpumask);
else
kthread_bind_mask(rescuer->task, cpu_possible_mask);
wake_up_process(rescuer->task);
--
2.39.3