Re: [Bug #11989] Suspend failure on NForce4-based boards due tochanes in stop_machine

[Ingo Molnar]

* Rafael J. Wysocki <rjw@xxxxxxx> wrote:

> However, it is reproducible by doing
> 
> # echo core > /sys/power/pm_test
> 
> and repeating
> 
> # echo disk > /sys/power/state
> 
> for a couple of times, in which case the last two lines printed to the console
> before a (solid) hang are:
> 
> SMP alternatives: switching to SMP code
> Booting processor 1 APIC 0x1 ip 0x6000
> 
> So, it evidently fails while re-enabling the non-boot CPU and not 
> during disabling it as I thought before.
> 
> With commit c9583e55fa2b08a230c549bd1e3c0bde6c50d9cc reverted the 
> issue is not reproducible any more.

[ Cc:-ed workqueue/locking/suspend-race-condition experts. ]

Seems like the new kernel/stop_machine.c logic has a race for the test 
sequence above. (Below is the bisected commit again, maybe the race is 
visible via email review as well.)

	Ingo

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