Messages in this thread | | | Subject | Re: [lhcs-devel] Re: CPU Hotplug broken -mm5 onwards | From | Rusty Russell <> | Date | Tue, 20 Apr 2004 09:07:57 +1000 |
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On Tue, 2004-04-20 at 08:55, Nick Piggin wrote: > > So, as Rusty said, I think we really need to consider removing > > lock_cpu_hotplug from sched_migrate_task. AFAICS that lock > > was needed to prevent adding tasks to dead cpus. The same > > can be accomplished by removing lock_cpu_hotplug from sched_migrate_task > > and adding a cpu_is_offline check in __migrate_task. > > This will eliminate all the deadlocks I have been hitting. > > > > Yes this would be a better idea. Care to send Andrew a patch > against -mm?
What surprises me is that this is a regression. The original hotplug code on top of Nicksched(TM) removed that lock as part of the "don't change cpus_allowed to migrate on exec" fix. When we pushed the patch straight into Linus' tree, we had to do lock_cpu_hotplug because we didn't have that code.
Obviously, it escaped somewhere...
Cheers, Rusty. -- Anyone who quotes me in their signature is an idiot -- Rusty Russell
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