Messages in this thread | | | From | Andi Kleen <> | Subject | Re: [PATCH v2 1/5] x86: replace timeouts when booting secondary CPU with infinite wait loop | Date | Wed, 02 Apr 2014 10:15:29 -0700 |
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Igor Mammedov <imammedo@redhat.com> writes:
> Hang is observed on virtual machines during CPU hotplug, > especially in big guests with many CPUs. (It reproducible > more often if host is over-committed). > > It happens because master CPU gives up waiting on > secondary CPU and allows it to run wild. As result > AP causes locking or crashing system. For example > as described here: https://lkml.org/lkml/2014/3/6/257 > > If master CPU have sent STARTUP IPI successfully, > make it wait indefinitely till AP boots.
But what happens on a real machine when the other CPU is dead?
I've seen that. Kernel still boots. With your patch it would hang.
I don't think you can do that. It needs to have some timeout. Maybe a longer or configurable one?
-Andi
-- ak@linux.intel.com -- Speaking for myself only
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