[Qemu-devel] hitting intermittent issue with live migration from qemu-kvm-ev 2.3.0 to qemu-kvm-ev 2.6.0

[Chris Friesen]

Hi,

I'm running into an issue with live-migrating a guest from a host running 
qemu-kvm-ev 2.3.0-31 to a host running qemu-kvm-ev 2.6.0-27.1.  This is a 
libvirt-tunnelled migration, in the context of upgrading an OpenStack install to 
newer software.  The source host is running CentOS 7.2.1511, while the dest host 
is running CentOS 7.3.1611.

I'll include the qemu commandlines for the source/dest at the bottom.

Initially we have a bunch of guests running on compute-2 (which is running 
qemu-kvm-ev 2.3.0).  We then started live-migrating them one at a time to 
compute-0 (which is running qemu-kvm-ev 2.6.0).  Three of them migrated 
successfully.  The fourth (which was essentially identical in configuration to 
the first three) failed, as per the following logs in 
/var/log/libvirt/qemu/instance-0000000e.log:


2017-03-29T06:38:37.886940Z qemu-kvm: VQ 2 size 0x80 < last_avail_idx 0x47b - 
used_idx 0x47c
2017-03-29T06:38:37.886974Z qemu-kvm: error while loading state for instance 0x0 
of device '0000:00:07.0/virtio-balloon'
2017-03-29T06:38:37.888684Z qemu-kvm: load of migration failed: Operation not 
permitted
2017-03-29 06:38:37.896+0000: shutting down


Does anyone know of an existing bug report covering this issue?  (I took a look 
and didn't see anything obviously related.)


The qemu commandline on the source compute node is:


/usr/libexec/qemu-kvm -c 0x00000000000000000000000000000001 -n 4 
--proc-type=secondary --file-prefix=vs -- -enable-dpdk -name instance-0000000e 
-S -machine pc-i440fx-rhel7.2.0,accel=kvm,usb=off -m 512 -realtime mlock=off 
-smp 1,sockets=1,cores=1,threads=1 -object 
memory-backend-file,id=ram-node0,prealloc=yes,mem-path=/mnt/huge-2048kB/libvirt/qemu,share=yes,size=536870912,host-nodes=1,policy=bind 
-numa node,nodeid=0,cpus=0,memdev=ram-node0 -uuid 
57ae849f-aa66-422a-90a2-62db6c59db29 -smbios type=1,manufacturer=Fedora 
Project,product=OpenStack 
Nova,version=13.0.0-0.tis.4,serial=4c8121f1-d927-424e-8712-88b1de45be37,uuid=57ae849f-aa66-422a-90a2-62db6c59db29,family=Virtual 
Machine -no-user-config -nodefaults -chardev 
socket,id=charmonitor,path=/var/lib/libvirt/qemu/domain-instance-0000000e/monitor.sock,server,nowait 
-mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc,driftfix=slew 
-global kvm-pit.lost_tick_policy=discard -no-hpet -no-shutdown -boot 
reboot-timeout=5000,strict=on -device 
piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive 
file=/dev/disk/by-path/ip-192.168.205.6:3260-iscsi-iqn.2010-10.org.openstack:volume-ac57fcaa-7ecd-4d3b-8671-3bc740337a42-lun-0,if=none,id=drive-virtio-disk0,format=raw,serial=ac57fcaa-7ecd-4d3b-8671-3bc740337a42,cache=none,aio=native 
-device 
virtio-blk-pci,scsi=off,bus=pci.0,addr=0x6,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 
-chardev 
socket,id=charnet0,path=/var/run/vswitch/usvhost-9e574d3c-32dd-4d39-97e6-447b15fb00b4 
-netdev type=vhost-user,id=hostnet0,chardev=charnet0 -device 
virtio-net-pci,netdev=hostnet0,id=net0,mac=fa:16:3e:b0:59:a9,bus=pci.0,addr=0x3 
-chardev 
socket,id=charnet1,path=/var/run/vswitch/usvhost-7bc48d91-f215-4394-99ff-eb7f20d9ff1e 
-netdev type=vhost-user,id=hostnet1,chardev=charnet1 -device 
virtio-net-pci,netdev=hostnet1,id=net1,mac=fa:16:3e:8b:6f:09,bus=pci.0,addr=0x4 
-chardev 
socket,id=charnet2,path=/var/run/vswitch/usvhost-c32e2d0d-9ed4-4f4b-abc9-539a12a86008 
-netdev type=vhost-user,id=hostnet2,chardev=charnet2 -device 
virtio-net-pci,netdev=hostnet2,id=net2,mac=fa:16:3e:07:ca:a0,bus=pci.0,addr=0x5 
-chardev 
file,id=charserial0,path=/etc/nova/instances/57ae849f-aa66-422a-90a2-62db6c59db29/console.log 
-device isa-serial,chardev=charserial0,id=serial0 -chardev pty,id=charserial1 
-device isa-serial,chardev=charserial1,id=serial1 -device usb-tablet,id=input0 
-vnc 0.0.0.0:11 -k en-us -device cirrus-vga,id=video0,bus=pci.0,addr=0x2 
-incoming fd:25 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x7 -msg 
timestamp=on



The complete instance-0000000e.log file on the destination is:

2017-03-29 06:38:35.962+0000: starting up libvirt version: 2.0.0, package: 
10.el7_3.2.tis.24 (Unknown, 2017-03-15-14:59:22, yow-dsulliva-lx-vm1.wrs.com), 
qemu version: 2.6.0 (qemu-kvm-ev-2.6.0-27.1.el7.tis.31), hostname: compute-0
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin 
QEMU_AUDIO_DRV=none /usr/libexec/qemu-kvm '-c 
0x00000000000000000000000000000001' '-n 4' --proc-type=secondary 
--file-prefix=vs -- -enable-dpdk -name guest=instance-0000000e,debug-threads=on 
-S -object 
secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-10-instance-0000000e/master-key.aes 
-machine pc-i440fx-rhel7.2.0,accel=kvm,usb=off -m 512 -realtime mlock=off -smp 
1,sockets=1,cores=1,threads=1 -object 
memory-backend-file,id=ram-node0,prealloc=yes,mem-path=/mnt/huge-2048kB/libvirt/qemu,share=yes,size=536870912,host-nodes=0,policy=bind 
-numa node,nodeid=0,cpus=0,memdev=ram-node0 -uuid 
57ae849f-aa66-422a-90a2-62db6c59db29 -smbios 'type=1,manufacturer=Fedora 
Project,product=OpenStack 
Nova,version=13.0.0-0.tis.4,serial=4c8121f1-d927-424e-8712-88b1de45be37,uuid=57ae849f-aa66-422a-90a2-62db6c59db29,family=Virtual 
Machine' -no-user-config -nodefaults -chardev 
socket,id=charmonitor,path=/var/lib/libvirt/qemu/domain-10-instance-0000000e/monitor.sock,server,nowait 
-mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc,driftfix=slew 
-global kvm-pit.lost_tick_policy=discard -no-hpet -no-shutdown -boot 
reboot-timeout=5000,strict=on -device 
piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive 
file=/dev/disk/by-path/ip-192.168.205.6:3260-iscsi-iqn.2010-10.org.openstack:volume-ac57fcaa-7ecd-4d3b-8671-3bc740337a42-lun-0,format=raw,if=none,id=drive-virtio-disk0,serial=ac57fcaa-7ecd-4d3b-8671-3bc740337a42,cache=none,aio=native 
-device 
virtio-blk-pci,scsi=off,bus=pci.0,addr=0x6,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 
-chardev 
socket,id=charnet0,path=/var/run/vswitch/usvhost-9e574d3c-32dd-4d39-97e6-447b15fb00b4 
-netdev type=vhost-user,id=hostnet0,chardev=charnet0 -device 
virtio-net-pci,netdev=hostnet0,id=net0,mac=fa:16:3e:b0:59:a9,bus=pci.0,addr=0x3 
-chardev 
socket,id=charnet1,path=/var/run/vswitch/usvhost-7bc48d91-f215-4394-99ff-eb7f20d9ff1e 
-netdev type=vhost-user,id=hostnet1,chardev=charnet1 -device 
virtio-net-pci,netdev=hostnet1,id=net1,mac=fa:16:3e:8b:6f:09,bus=pci.0,addr=0x4 
-chardev 
socket,id=charnet2,path=/var/run/vswitch/usvhost-c32e2d0d-9ed4-4f4b-abc9-539a12a86008 
-netdev type=vhost-user,id=hostnet2,chardev=charnet2 -device 
virtio-net-pci,netdev=hostnet2,id=net2,mac=fa:16:3e:07:ca:a0,bus=pci.0,addr=0x5 
-add-fd set=0,fd=51 -chardev file,id=charserial0,path=/dev/fdset/0,append=on 
-device isa-serial,chardev=charserial0,id=serial0 -chardev pty,id=charserial1 
-device isa-serial,chardev=charserial1,id=serial1 -device usb-tablet,id=input0 
-vnc 0.0.0.0:9 -k en-us -device cirrus-vga,id=video0,bus=pci.0,addr=0x2 
-incoming defer -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x7 -msg 
timestamp=on
Domain id=10 is tainted: high-privileges
EAL:eal_memory.c:1591: WARNING: Address Space Layout Randomization (ASLR) is 
enabled in the kernel.
EAL:eal_memory.c:1593:    This may cause issues with mapping memory into 
secondary processes
char device redirected to /dev/pts/9 (label charserial1)
2017-03-29T06:38:37.886940Z qemu-kvm: VQ 2 size 0x80 < last_avail_idx 0x47b - 
used_idx 0x47c
2017-03-29T06:38:37.886974Z qemu-kvm: error while loading state for instance 0x0 
of device '0000:00:07.0/virtio-balloon'
2017-03-29T06:38:37.888684Z qemu-kvm: load of migration failed: Operation not 
permitted
2017-03-29 06:38:37.896+0000: shutting down


For what it's worth, the differences between the two qemu command lines are as 
follows:

source:
-name instance-0000000e -chardev 
file,id=charserial0,path=/etc/nova/instances/57ae849f-aa66-422a-90a2-62db6c59db29/console.log 
-vnc 0.0.0.0:9 -incoming fd:25

destination:
-name guest=instance-0000000e,debug-threads=on -object 
secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-10-instance-0000000e/master-key.aes 
-add-fd set=0,fd=51 -chardev file,id=charserial0,path=/dev/fdset/0,append=on 
-vnc 0.0.0.0:11 -incoming defer

Thanks,
Chris