Merge tag 'wq-for-6.13-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq

Pull workqueue fix from Tejun Heo:

 - Add a WARN_ON_ONCE() on queue_delayed_work_on() on an offline CPU as
   such work items won't get executed till the CPU comes back online

* tag 'wq-for-6.13-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
  workqueue: warn if delayed_work is queued to an offlined cpu.

Author: torvalds

kernel/workqueue.c

@@ -2508,6 +2508,7 @@ static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
 		return;
 	}
 
+	WARN_ON_ONCE(cpu != WORK_CPU_UNBOUND && !cpu_online(cpu));
 	dwork->wq = wq;
 	dwork->cpu = cpu;
 	timer->expires = jiffies + delay;
@@ -2533,6 +2534,12 @@ static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
  * @dwork: work to queue
  * @delay: number of jiffies to wait before queueing
  *
+ * We queue the delayed_work to a specific CPU, for non-zero delays the
+ * caller must ensure it is online and can't go away. Callers that fail
+ * to ensure this, may get @dwork->timer queued to an offlined CPU and
+ * this will prevent queueing of @dwork->work unless the offlined CPU
+ * becomes online again.
+ *
  * Return: %false if @work was already on a queue, %true otherwise.  If
  * @delay is zero and @dwork is idle, it will be scheduled for immediate
  * execution.