Re: [PATCH v3] workqueue: don't skip lockdep work dependency in cancel_work_sync()

From: Tejun Heo
Date: Mon Aug 15 2022 - 21:26:57 EST


On Fri, Jul 29, 2022 at 01:30:23PM +0900, Tetsuo Handa wrote:
> Like Hillf Danton mentioned
>
> syzbot should have been able to catch cancel_work_sync() in work context
> by checking lockdep_map in __flush_work() for both flush and cancel.
>
> in [1], being unable to report an obvious deadlock scenario shown below is
> broken. From locking dependency perspective, sync version of cancel request
> should behave as if flush request, for it waits for completion of work if
> that work has already started execution.

Applied to cgroup/for-6.0-fixes.

Thanks.

--
tejun