UBUNTU-CVE-2026-89922: High severity ubuntu/linux-aws vulnerability

In the Linux kernel, the following vulnerability has been resolved: KVM: s390: Take srcu when importing watchpoint data importwpinfo() backs up the original guest memory contents of a watchpoint with readguestabs(), which is kvmreadguest() and therefore resolves the memslot via kvmmemslots(). That requires kvm->srcu (or kvm->slotslock) to be held, otherwise a concurrent memslot update can free the memslots array under us once its SRCU grace period has elapsed. As this is not fast path, following lock ordering (mutex first, then srcu) take the big hammer and hold the srcu for the full import.