Re: workqueue code needing preemption disabled

[Tejun Heo <tj@kernel.org>]

Hello, Steven.

On Mon, Mar 18, 2013 at 12:30:43PM -0400, Steven Rostedt wrote:
> If you happen to know the critical areas that require preemption to be
> disabled for real, we can encapsulate them with:
> 
> 	preempt_disable_rt();
> 
> 	preempt_enable_rt();
> 
> These are currently only in the -rt patch, but it annotates locations
> that require preemption to be disabled even when -rt converts spin_locks
> into mutexes. These obviously can not contain spin_locks() as
> spin_locks() can block and schedule out.

Making gcwq locks disable preemption would be much safer / easier, but
if that's not desirable, anything touching gcwq->idle_list would be a
good place to start - worker_enter_idle() and worker_leave_idle().
Hmmm... ignoring CPU hotplug, I think those two might just do it.
Give it a try?  How reproducible is the problem?

Thanks.

-- 
tejun