Re: [3.14] core onlining/hotplug regression
From: Thomas Gleixner
Date: Fri Jul 25 2014 - 05:05:54 EST
On Fri, 25 Jul 2014, Daniel J Blueman wrote:
> On a larger x86 system with 1728 cores, 3.15(.6) asserts on
> smpboot_thread_fn's td->cpu != smp_processor_id() consistently after ~1500
> cores are online.
> Reverting the only directly related changes I could find [1,2] doesn't help.
> Debugging indicates there is a race where the created thread is quickly
> migrated to core 0 when this occurs, since smp_processor_id returns 0 in these
> cases. Thomas introduced a thread parked state to fix related issues a year
> back. Linux 3.14(.13) boots just nice.
Weird. Commits [1,2] are definitely not the culprits.
> Full boot output is at:
Not really helpful, as we don't see what causes it. We just see the
> Any theories so far? I'll start bisecting when I have full access to the
> system again in a week and I'll do some more debugging with intermittent
> access before then.
One thing you could try is enabling tracing.
It'll take a looooong time to spill out the traces, but that should
give us the root cause precisely.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/