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.