[libvirt-users] "virsh list" hangs

[Yunchih Chen]

On 02/20/2017 09:10 PM, Michal Privoznik wrote:
> On 17.02.2017 17:18, Yunchih Chen wrote:
>> `virsh list` hangs on my server that hosts a bunch of VMs.
>> This might be due to the Debian upgrade I did on Feb 15, which upgrades
>> `libvirt` from 2.4.0-1 to 3.0.0-2.
>> I have tried restarting libvirtd for a few times, without luck.
>>
>> Attached below are some relevant logs; let me know if you need some more
>> for debugging.
>> Thanks for your help!!
>>
>> root at vm-host:~# uname -a
>> Linux vm-host 4.6.0-1-amd64 #1 SMP Debian 4.6.4-1 (2016-07-18) x86_64
>> GNU/Linux
>>
>> root at vm-host:~# apt-cache policy libvirt-daemon
>> libvirt-daemon:
>>    Installed: 3.0.0-2
>>    Candidate: 3.0.0-2
>>    Version table:
>>   *** 3.0.0-2 500
>>          500 http://debian.csie.ntu.edu.tw/debian testing/main amd64
>> Packages
>>          100 /var/lib/dpkg/status
>>
>> root at vm-host:~# strace -o /tmp/trace -e trace=network,file,poll virsh
>> list  # hangs forever .....
>> ^C
>> root at vm-host:~# tail -10 /tmp/trace
>> access("/etc/libvirt/libvirt.conf", F_OK) = 0
>> open("/etc/libvirt/libvirt.conf", O_RDONLY) = 5
>> access("/proc/vz", F_OK)                = -1 ENOENT (No such file or
>> directory)
>> socket(AF_UNIX, SOCK_STREAM, 0)         = 5
>> connect(5, {sa_family=AF_UNIX,
>> sun_path="/var/run/libvirt/libvirt-sock"}, 110) = 0
>> getsockname(5, {sa_family=AF_UNIX}, [128->2]) = 0
>> poll([{fd=5, events=POLLOUT}, {fd=6, events=POLLIN}], 2, -1) = 1
>> ([{fd=5, revents=POLLOUT}])
>> poll([{fd=5, events=POLLIN}, {fd=6, events=POLLIN}], 2, -1) = ?
>> ERESTART_RESTARTBLOCK (Interrupted by signal)
>> --- SIGINT {si_signo=SIGINT, si_code=SI_KERNEL} ---
>> +++ killed by SIGINT +++
>>
>> root at vm-host:~# lsof /var/run/libvirt/libvirt-sock # hangs too ...
> This is very suspicious. Looks like the daemon is in some weird state
> and hence virsh is unable to get list of domains.
>
> # ps axf | grep libvirtd
> # gdb -p $(pgrep libvirtd)
> (gdb) t a a bt
>
> if you could run those commands and share the output that might shed
> more light.
>
> Michal

Unfortunately, gdb also hangs when attaching to libvirt ....

root at vm-host:~# gdb -q -p $(pgrep libvirtd)
Attaching to process 9556
[New LWP 9557]
[New LWP 9558]
[New LWP 9559]
[New LWP 9560]
[New LWP 9561]
[New LWP 9562]
[New LWP 9563]
[New LWP 9564]
[New LWP 9565]
[New LWP 9566]
[New LWP 9567]
[New LWP 9568]
[New LWP 9569]
[New LWP 9570]
[New LWP 9571]
[New LWP 9572]
^C^C^C^C^C^C^C^C^C^C^C

It must be killed with SIGKILL, and libvirtd will die with gdb.

Here[1] is the output of the following command:

strace -o /tmp/gdb-full-trace.txt -s 1024 -f gdb -q -p $(pgrep libvirtd)

Thanks for your help : )

[1] https://www.csie.ntu.edu.tw/~yunchih/s/gdb-full-trace.txt

-- 
--
Yun-Chih Chen 陳耘志
Network/Workstation Assistant
Dept. of Computer Science and Information Engineering
National Taiwan University
Tel: +886-2-33664888 ext. 217/204
Email: ta217 at csie.ntu.edu.tw
Website: http://wslab.csie.ntu.edu.tw/