This is a note to let you know that I've just added the patch titled
workqueue: Override implicit ordered attribute in workqueue_apply_unbound_cpumask()
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
workqueue-override-implicit-ordered-attribute-in-wor.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit b576fe0b85ab550dbc4d3106c7c0fa064dabc72d
Author: Waiman Long <longman@xxxxxxxxxx>
Date: Tue Oct 10 22:48:42 2023 -0400
workqueue: Override implicit ordered attribute in workqueue_apply_unbound_cpumask()
[ Upstream commit ca10d851b9ad0338c19e8e3089e24d565ebfffd7 ]
Commit 5c0338c68706 ("workqueue: restore WQ_UNBOUND/max_active==1
to be ordered") enabled implicit ordered attribute to be added to
WQ_UNBOUND workqueues with max_active of 1. This prevented the changing
of attributes to these workqueues leading to fix commit 0a94efb5acbb
("workqueue: implicit ordered attribute should be overridable").
However, workqueue_apply_unbound_cpumask() was not updated at that time.
So sysfs changes to wq_unbound_cpumask has no effect on WQ_UNBOUND
workqueues with implicit ordered attribute. Since not all WQ_UNBOUND
workqueues are visible on sysfs, we are not able to make all the
necessary cpumask changes even if we iterates all the workqueue cpumasks
in sysfs and changing them one by one.
Fix this problem by applying the corresponding change made
to apply_workqueue_attrs_locked() in the fix commit to
workqueue_apply_unbound_cpumask().
Fixes: 5c0338c68706 ("workqueue: restore WQ_UNBOUND/max_active==1 to be ordered")
Signed-off-by: Waiman Long <longman@xxxxxxxxxx>
Signed-off-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 8e108c040cc35..19868cf588779 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -5379,9 +5379,13 @@ static int workqueue_apply_unbound_cpumask(void)
list_for_each_entry(wq, &workqueues, list) {
if (!(wq->flags & WQ_UNBOUND))
continue;
+
/* creating multiple pwqs breaks ordering guarantee */
- if (wq->flags & __WQ_ORDERED)
- continue;
+ if (!list_empty(&wq->pwqs)) {
+ if (wq->flags & __WQ_ORDERED_EXPLICIT)
+ continue;
+ wq->flags &= ~__WQ_ORDERED;
+ }
ctx = apply_wqattrs_prepare(wq, wq->unbound_attrs);
if (!ctx) {
