Re: next: WARNING: CPU: 0 PID: 63 at kernel/workqueue.c:1999 worker_enter_idle+0xb2/0xc0

22 May 2023

On Mon, May 22, 2023 at 08:20:38AM -1000, Tejun Heo wrote:
...
Hello,
On Mon, May 22, 2023 at 09:24:09PM +0800, Z qiang wrote:
...

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 9c5c1cfa478f..f8d739fef311 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1060,10 +1060,9 @@ void wq_worker_running(struct task_struct *task)
         * and leave with an unexpected pool->nr_running == 1 on the newly
unbound
         * pool. Protect against such race.
         */

  preempt_disable();




  local_irq_disable();
  if (!(worker->flags & WORKER_NOT_RUNNING))
          worker->pool->nr_running++;




  preempt_enable();

  /*
   * CPU intensive auto-detection cares about how long a work item



hogged
@@ -1072,6 +1071,7 @@ void wq_worker_running(struct task_struct *task)
        worker->current_at = worker->task->se.sum_exec_runtime;
    worker->sleeping = 0;


  local_irq_enable();



}
Ah, yeah, this is correct. Now we're modifying nr_running from timer tick
too, so if don't block irq, the timer tick can ruin the not-irq-protected
read-write-modify nr_running update from wq_worker_running(). Naresh, can
you please confirm the fix?
Z qiang, while waiting for Naresh's test result, can you send the fix as a
proper signed-off-patch?
Thanks.
-- 
tejun

    