(In reply to John Carrick Smith from comment #4) > 1. Tried with intel_iommu=off on the boot command line and it made no > difference. > > 2. How do I produce the full stack trace please? The journal was cut off by some reason. Maybe you can get more when sync and unmount via sysrq before the reboot / reset. e.g. at hangup, try the sysrq combo alt-sysrq-k, alt-sysrq-s, alt-sysrq-u, then alt-sysrq-b.