[libvirt-users] "virsh list" hangs

[Yunchih Chen]

On 02/24/2017 11:59 PM, Daniel P. Berrange wrote:
> On Fri, Feb 24, 2017 at 11:52:43PM +0800, Yunchih Chen wrote:
>>
>> On 02/24/2017 11:30 PM, Daniel P. Berrange wrote:
>>> On Tue, Feb 21, 2017 at 12:07:41PM +0800, Yunchih Chen wrote:
>>>> 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)
>>> Err, that is useless - you've just straced GDB, not libvirtd
>>>
>>> You need to strace libvirtd as it starts
>>>
>>>      strace -o libvirt.log -f -s 1000 /usr/sbin/libvirtd
>>>
>> Here[1] is the output of the above command.
>>
>> [1] https://www.csie.ntu.edu.tw/~yunchih/s/libvirtd-strace.log
> So this appears to show it hanging on the following:
>
>     17082 lstat("/home/xxxx/mnt",  <unfinished ...>
>
> Presumably '/home/xxx/mnt/' is a mount point and whatever storage is
> behind there appears to be dead / nonresponsive.
>
> You'll need to either fix this mount point, or delete the XML config
> for the storage pool that is associated with /home/xxxx/ from the
> /etc/libvirt/storage/ directory.
>
>
> Regards,
> Daniel
Thanks!  This fixes the hanging virsh!!!

-- 
--
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/