Messages in this thread | | | Date | Wed, 27 Apr 2011 15:12:19 -0700 | From | Michael Bohan <> | Subject | Re: console_cpu_notify can cause scheduling BUG during CPU hotplug |
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On 4/27/2011 12:38 AM, Borislav Petkov wrote: > Great, whatever you guys come up with, we'd like to give it a run too. > We (AMD) hit the same issue in one of our tests but in our case we end > up in an endless loop of the state machine at stop_machine_cpu_stop() > since the core being offlined cannot ack the state transition to > STOPMACHINE_EXIT due to a similar reason. > > One possible fix is dropping CPU_DYING from console_cpu_notify() > since it is called into by the offlining path in > kernel/cpu.c::take_cpu_down().
This seems to be a different problem. Could you elaborate about why removing CPU_DYING from console_cpu_notify resolves your problem? What are other possible fixes?
In the failure case I witnessed, we're attempting to sleep in atomic mode, which is a clear violation caused by the addition of CPU_DYING. I haven't thoroughly investigated whether other actions in console_cpu_notify (eg. ONLINE, DEAD, DOWN_FAILED, UP_CANCELED) are in atomic mode violation as well.
Thanks, Mike
-- Employee of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum
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