linux-next: KVM/s390x regression (was: [v7 03/16] mm/huge_memory: add device-private THP support to PMD operations)

Christian Borntraeger
2025-10-17T14:49:56Z

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?

Christian Borntraeger