Re: Help needed: Resume problems in 2.6.32-rc, perhaps related topreempt_count leakage in keventd

[Linus Torvalds]

On Mon, 9 Nov 2009, Thomas Gleixner wrote:
> 
> I think it _IS_ releated because the worker_thread is CPU affine and
> the debug_smp_processor_id() check does:

Hmm. We do know CPU affinity is destroyed by CPU hotplug. People have 
complained about that before (for user-space processes that get moved 
around due to hot-unplug/plug).

And the suspend/resume process does CPU hotplug to take down all but one 
CPU. The workqueues should act on those events already, but maybe there's 
a bug somewhere. None of that is new to 32-rc, though - is it?

And workqueue_cpu_callback() seems buggy. It loops over the 'workqueues' 
list with no protection. Yes, we do 'stop_machine' for CPU hotplug events, 
but only for the very internal one (CPU_DYING) will the CPU notifiers be 
called with the machine stopped).

Hmm. I don't see any changes in kernel/cpu.c or kernel/workqueue.c that 
look at all relevant. But scheduler changes could certainly matter.

			Linus
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