From: Tejun Heo <tj@kernel.org>
To: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: kernel test robot <lkp@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
linux-kernel@vger.kernel.org, LKP <lkp@lists.01.org>,
Lai Jiangshan <jiangshanlai@gmail.com>
Subject: Re: [PATCH v2] workqueue: Remove the warning in wq_worker_sleeping()
Date: Fri, 3 Apr 2020 10:53:26 -0400 [thread overview]
Message-ID: <20200403145326.GA162390@mtj.duckdns.org> (raw)
In-Reply-To: <20200327232959.rpylymw2edhtxuwr@linutronix.de>
Hello,
On Sat, Mar 28, 2020 at 12:29:59AM +0100, Sebastian Andrzej Siewior wrote:
> The kernel test robot triggered a warning with the following race:
> task-ctx A interrupt-ctx B
> worker
> -> process_one_work()
> -> work_item()
> -> schedule();
> -> sched_submit_work()
> -> wq_worker_sleeping()
> -> ->sleeping = 1
> atomic_dec_and_test(nr_running)
> __schedule(); *interrupt*
> async_page_fault()
> -> local_irq_enable();
> -> schedule();
> -> sched_submit_work()
> -> wq_worker_sleeping()
> -> if (WARN_ON(->sleeping)) return
> -> __schedule()
> -> sched_update_worker()
> -> wq_worker_running()
> -> atomic_inc(nr_running);
> -> ->sleeping = 0;
>
> -> sched_update_worker()
> -> wq_worker_running()
> if (!->sleeping) return
>
> In this context the warning is pointless everything is fine.
This is not a usual control flow, right? Can we annotate this case specifically
instead of weakening santiy check for generic cases?
Thanks.
--
tejun
next prev parent reply other threads:[~2020-04-03 14:53 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-27 7:43 6d25be5782 ("sched/core, workqueues: Distangle worker .."): [ 52.816697] WARNING: CPU: 0 PID: 14 at kernel/workqueue.c:882 wq_worker_sleeping kernel test robot
2020-03-27 17:53 ` [PATCH] workqueue: Don't double assign worker->sleeping Sebastian Andrzej Siewior
2020-03-27 23:29 ` [PATCH v2] workqueue: Remove the warning in wq_worker_sleeping() Sebastian Andrzej Siewior
2020-04-03 14:53 ` Tejun Heo [this message]
2020-04-03 19:29 ` Sebastian Andrzej Siewior
2020-04-03 17:45 ` Daniel Jordan
2020-04-03 18:25 ` Sebastian Andrzej Siewior
2020-04-03 19:05 ` Daniel Jordan
2020-04-01 3:22 ` [PATCH] workqueue: Don't double assign worker->sleeping Lai Jiangshan
2020-04-01 3:44 ` Lai Jiangshan
2020-04-01 13:03 ` Sebastian Andrzej Siewior
2020-04-02 0:07 ` Lai Jiangshan
2020-04-02 7:29 ` Sebastian Andrzej Siewior
2020-04-08 12:20 ` [tip: sched/urgent] workqueue: Remove the warning in wq_worker_sleeping() tip-bot2 for Sebastian Andrzej Siewior
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