Subject: Re: linux-next: KVM/s390x regression

From: David Hildenbrand <[email-masked]>
Date: Fri, 17 Oct 2025 16:54:09 +0200

On 17.10.25 16:49, Christian Borntraeger wrote:
> This patch triggers a regression for s390x kvm as qemu guests can no longer start
> 
> error: kvm run failed Cannot allocate memory
> PSW=mask 0000000180000000 addr 000000007fd00600
> R00=0000000000000000 R01=0000000000000000 R02=0000000000000000 R03=0000000000000000
> R04=0000000000000000 R05=0000000000000000 R06=0000000000000000 R07=0000000000000000
> R08=0000000000000000 R09=0000000000000000 R10=0000000000000000 R11=0000000000000000
> R12=0000000000000000 R13=0000000000000000 R14=0000000000000000 R15=0000000000000000
> C00=00000000000000e0 C01=0000000000000000 C02=0000000000000000 C03=0000000000000000
> C04=0000000000000000 C05=0000000000000000 C06=0000000000000000 C07=0000000000000000
> C08=0000000000000000 C09=0000000000000000 C10=0000000000000000 C11=0000000000000000
> C12=0000000000000000 C13=0000000000000000 C14=00000000c2000000 C15=0000000000000000
> 
> KVM on s390x does not use THP so far, will investigate. Does anyone have a quick idea?

Only when running KVM guests and apart from that everything else seems 
to be fine?

That's weird :)

-- 
Cheers

David / dhildenb