On Wed, Apr 02, 2014 at 11:29:56PM +0200, Igor Mammedov wrote: > On Wed, 02 Apr 2014 10:15:29 -0700 > Andi Kleen <a...@firstfloor.org> wrote: > > > Igor Mammedov <imamm...@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? > One possible way to boot such machine would be to disable dead CPU > in kernel parameters.
That would need explicit user action. It's much better to recover automatically, even if somewhat crippled. -Andi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
