Note: This bug is displayed in read-only format because
the product is no longer active in Red Hat Bugzilla.
RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.
In one shell, I started a migration with:
virsh migrate --live --desturi 'qemu+ssh://root@hybrid0/system' spice
In a second shell, I stopped libvirtd:
service libvirtd stop
The guest remained running during the migration until I stopped the source libvirtd at which point it became paused until I started libvirtd again. I think the guest should continue to run while libvirtd is stopped, as it would if no migration had been taking place.
It's because in normal (non-tunneled) migration libvirtd is not involved in the actual migration process. It just sets everything up, tells qemu to start migration and once that ends (successfully or not), libvirt resumes one of the domains and kills the other one. When the live migration enters its last phase, qemu pauses the domain and transfers the rest of its state. And it stays paused until libvirtd starts and notices that the domain is paused for migration couldn't successfully finish without libvirtd and resumes it.
IMHO the only way to fix this is to route migration data through libvirt so that if libvirtd crashes or is stopped, the migration is automatically canceled since qemu will not be able to send migration data.
Actually, there might be another solution. Qemu could be patched to cancel migration in case the monitor connection that requested it is closed. But I have no idea how feasible this is.
This is not an issue in practice since a crashed libvirtd will be followed by its restart (systemd restarts the daemon automatically and so does RHEV on RHEL-6 via upstart) and libvirtd will cancel the migration when it starts. I think there's no need to spend time on this bug.