Note: This bug is displayed in read-only format because
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Cause:
When libvirt is restarted after a hugetlbfs was mounted and a guest is running, libvirt tries to create guest specific path in the new hugetlbfs mount point. Because of a bug in namespace code this fails which results in the guest being killed by libvirt.
Consequence:
Guest is killed on libvirtd restart.
Fix:
Twofold. Firstly, the namespace code was fixed so that creating this guest specific path now succeeds. Secondly, the creation is postponed until really needed (memory hotplug).
Result:
Guests can now survive libvirtd restart.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory (libvirt bug fix update), and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
https://access.redhat.com/errata/RHBA-2023:0521
Preverified on scratch build: # rpm -q libvirt libvirt-8.0.0-8.4.el9_0_rc.d3c9a2f943.x86_64 Verify steps: 1. Prepare huge page memory: # echo 4 > /sys/kernel/mm/hugepages/hugepages-1048576kB/nr_hugepages # echo 2048 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages 2. Define a guest with below memorybacking xml. <memoryBacking> <hugepages> <page size='2048' unit='KiB'/> </hugepages> </memoryBacking> 3. Start the VM and stop virtqemud # virsh start vm1 && systemctl stop virtqemud Domain 'vm1' started Warning: Stopping virtqemud.service, but it can still be activated by: virtqemud-ro.socket virtqemud-admin.socket virtqemud.socket 4. Mount 1G hugepage path # mkdir /dev/hugepages1G # mount -t hugetlbfs -o pagesize=1G hugetlbfs /dev/hugepages1G 5. Do virsh list and guest still in running state. # virsh -r list --all Id Name State ---------------------- 1 vm1 running # virsh -r list --all Id Name State ---------------------- 1 vm1 running 6. Prepare memory device hotplug xml like below: # cat dimm1G.xml <memory model='dimm'> <source> <pagesize unit='KiB'>1048576</pagesize> <nodemask>0-1</nodemask> </source> <target> <size unit='KiB'>1048576</size> <node>0</node> </target> </memory> 7. Hotplug dimm memory device: # virsh attach-device vm1 dimm1G.xml Device attached successfully 8. Prepare memory device with 2M hugepage source hotplug xml like below: # cat dimm2M.xml <memory model='dimm'> <source> <pagesize unit='KiB'>2048</pagesize> <nodemask>0-1</nodemask> </source> <target> <size unit='KiB'>1048576</size> <node>0</node> </target> </memory> 9. Hotplug dimm memory device: # virsh attach-device vm1 dimm2M.xml Device attached successfully 10. Shutoff vm # virsh destroy vm1 Domain vm1 destroyed 11. Restart virtqemud # systemctl restart virtqemud 12. Start vm # virsh start vm1 Domain 'vm1' started Also check the below scenarios: Steps: 1. memory backing 2M guest vm start -> stop virtqemud -> mount 1G path -> start virtqemud -> hotplug 1G dimm -> restart vm -> restart virtqemud -> hotplug 1G dimm 2. mount 1G path -> memory backing 2M guest vm start -> restart virtqemud -> hogplug 1G dimm -> restart virtqemud -> restart vm ->hogplug 1G dimm Tested with these settings：remember_owner=1 or 0, memfd memory backing, default memory backing, 1G hugepage memory backing, 1G hugepage path as /mnt/hugepages1G