[Qemu-devel] qemu-kvm crashes doing migration with disks + blkdebug files (does not happen with qemu)

[Lucas Meneghel Rodrigues <lmr@redhat.com>]

Hi folks,

qemu-kvm is segfaulting when executing migration with blkdebug files.

19:50:02 DEBUG| Git repo qemu_kvm uri: git://github.com/avikivity/qemu.git
19:50:02 DEBUG| Git repo qemu_kvm branch: master
19:50:30 INFO | Commit hash for qemu_kvm is 
7879db7e9c09b92d9af1c143fbe2cc212ec89e4b (no tag found)

How to reproduce:

1) create a origin vm like:

/usr/local/autotest/tests/kvm/qemu -name 'vm1' -nodefaults -vga std 
-monitor 
unix:'/tmp/monitor-humanmonitor1-20111104-200902-95j0',server,nowait 
-qmp unix:'/tmp/monitor-qmpmonitor1-20111104-200902-95j0',server,nowait 
-serial unix:'/tmp/serial-20111104-200902-95j0',server,nowait -drive 
file=blkdebug:/usr/local/autotest/virt/blkdebug/default.conf:/tmp/kvm_autotest_root/images/rhel6.1-64.qcow2,index=0,if=virtio,cache=none,rerror=stop,werror=stop 
-device 
virtio-net-pci,netdev=idtzhBVb,mac='9a:d0:7b:07:18:72',id='id9JW3ZV' 
-netdev tap,id=idtzhBVb,fd=23 -m 2048 -smp 2 -vnc :0


2) create a destination vm like:

/usr/local/autotest/tests/kvm/qemu -name 'vm1' -nodefaults -vga std 
-monitor 
unix:'/tmp/monitor-humanmonitor1-20111104-201329-Ia9o',server,nowait 
-qmp unix:'/tmp/monitor-qmpmonitor1-20111104-201329-Ia9o',server,nowait 
-serial unix:'/tmp/serial-20111104-201329-Ia9o',server,nowait -drive 
file=blkdebug:/usr/local/autotest/virt/blkdebug/default.conf:/tmp/kvm_autotest_root/images/rhel6.1-64.qcow2,index=0,if=virtio,cache=none,rerror=stop,werror=stop 
-device 
virtio-net-pci,netdev=idup1xAf,mac='9a:d0:7b:07:18:72',id='idyvOQf3' 
-netdev tap,id=idup1xAf,fd=19 -m 2048 -smp 2 -vnc :1  -S -incoming 
"exec:nc -l 5200"

Note that blkdebug file contains:

[inject-error]
state = "2"
event = "read_aio"
errno = "7"
immediately = "off"
once = "on"

[set-state]
state = "1"
event = "read_aio"
new_state = "2"

[set-state]
state = "2"
event = "read_aio"
new_state = "3"

Start the migration (on this example, using exec, but it reproduces with 
tcp and unix sockets):

11/04 20:13:30 DEBUG|kvm_monito:0254| (monitor humanmonitor1) Sending 
command 'migrate -d "exec:nc localhost 5200"'

Then you will have:

11/04 20:13:33 INFO |   aexpect:0783| [qemu output] invalid runstate 
transition
11/04 20:13:36 INFO |   aexpect:0783| [qemu output] /bin/sh: line 1: 
14695 Aborted                 (core dumped) 
/usr/local/autotest/tests/kvm/qemu -name 'vm1' -nodefaults -vga std 
-monitor 
unix:'/tmp/monitor-humanmonitor1-20111104-200902-95j0',server,nowait 
-qmp unix:'/tmp/monitor-qmpmonitor1-20111104-200902-95j0',server,nowait 
-serial unix:'/tmp/serial-20111104-200902-95j0',server,nowait -drive 
file=blkdebug:/usr/local/autotest/virt/blkdebug/default.conf:/tmp/kvm_autotest_root/images/rhel6.1-64.qcow2,index=0,if=virtio,cache=none,rerror=stop,werror=stop 
-device 
virtio-net-pci,netdev=idtzhBVb,mac='9a:d0:7b:07:18:72',id='id9JW3ZV' 
-netdev tap,id=idtzhBVb,fd=23 -m 2048 -smp 2 -vnc :0

We do have the core dumps available in case someone is interested in 
debugging the issue.

It is important to note that this problem is not happening with qemu.git 
master.