4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Waiman Long longman@redhat.com
[ 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@redhat.com Signed-off-by: Tejun Heo tj@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/workqueue.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/kernel/workqueue.c b/kernel/workqueue.c index 5533206cb6f48..0179390974517 100644 --- a/kernel/workqueue.c +++ b/kernel/workqueue.c @@ -5087,9 +5087,13 @@ 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) {