Linux kernel: powerpc: KVM guest can trigger host crash on Power8

[John Paul Adrian Glaubitz]

Hi Michael!

On 11/1/21 07:53, Michael Ellerman wrote:
> Sure, will give that a try.
> 
> I was able to crash my machine over the weekend, building openjdk, but I
> haven't been able to reproduce it for ~24 hours now (I didn't change
> anything).

I made another experiment and upgraded the host to 5.15-rc7 which contains your
fixes and made the guests build gcc-10. Interestingly, this time, the gcc-10
build crashed the guest but didn't manage to crash the host. I will update the
guest to 5.15-rc7 now as well and see how that goes.

> Can you try running your guests with no SMT threads?
> 
> I think one of your guests was using:
> 
>   -smp 32,sockets=1,dies=1,cores=8,threads=4
> 
> Can you change that to:
> 
>   -smp 8,sockets=1,dies=1,cores=8,threads=1
> 
> 
> And something similar for the other guest(s).

Sure. I will try that later. But first I want to switch the guests to 5.15-rc7 as well.

> If the system is stable with those settings that would be useful
> information, and would also mean you could use the system without it
> crashing semi regularly.

Gotcha.

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer - glaubitz at debian.org
`. `'   Freie Universitaet Berlin - glaubitz at physik.fu-berlin.de
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