iotop raises "UnboundLocalError: local variable 'pgpgin' referenced before assignment" in a ProxMox KVM

[Gilberto "Kowalsky" Martins]

Hello.

iotop just does not work in my ProxMox KVM boxes:
 $ iotop
 Traceback (most recent call last):
   File "/usr/sbin/iotop", line 10, in <module>
     from iotop.ui import main
   File "/usr/lib/python3/dist-packages/iotop/ui.py", line 46, in <module>
     from iotop.data import find_uids, TaskStatsNetlink, ProcessList, Stats
   File "/usr/lib/python3/dist-packages/iotop/data.py", line 51, in <module>
     vmstat_f = VmStat()
   File "/usr/lib/python3/dist-packages/iotop/vmstat.py", line 23, in __init__
     self.vmstat = self.read()
   File "/usr/lib/python3/dist-packages/iotop/vmstat.py", line 40, in read
     return pgpgin, pgpgout
 UnboundLocalError: local variable 'pgpgin' referenced before assignment

PVE Version:
 $ pveversion
 proxmox-ve: 6.4-1 (running kernel: 5.4.143-1-pve)

Ubuntu version:
 $ lsb_release -a
 No LSB modules are available.
 Distributor ID: Ubuntu
 Description: Ubuntu 20.04.4 LTS
 Release: 20.04
 Codename: focal

Kernel version:
 $ uname -a
 Linux prd1frm201 5.4.0-1065-kvm #68-Ubuntu SMP Wed May 18 23:28:33 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux

iotop version:
 $ sudo iotop -h
 Traceback (most recent call last):
   File "/usr/sbin/iotop", line 10, in <module>
     from iotop.ui import main
   File "/usr/lib/python3/dist-packages/iotop/ui.py", line 46, in <module>
     from iotop.data import find_uids, TaskStatsNetlink, ProcessList, Stats
   File "/usr/lib/python3/dist-packages/iotop/data.py", line 51, in <module>
     vmstat_f = VmStat()
   File "/usr/lib/python3/dist-packages/iotop/vmstat.py", line 23, in __init__
     self.vmstat = self.read()
   File "/usr/lib/python3/dist-packages/iotop/vmstat.py", line 40, in read
     return pgpgin, pgpgout
 UnboundLocalError: local variable 'pgpgin' referenced before assignment

 $ sudo apt show iotop |& grep -i version
 Version: 0.6-24-g733f3f8-1

[Robie Basak (racb)]

Thank you for taking the time to report this bug and helping to make Ubuntu better.

It looks like "pgpgin" and "pgpgout" are missing from /proc/vmstat in your environment, and that's what's causing the crash. Looking at the current upstream master branch at https://repo.or.cz/iotop.git/blob/HEAD:/iotop/vmstat.py this is a problem there too.

I'm not sure if iotop is expected to work correctly in an environment where these fields are missing, but this is really a question for iotop upstream.

To make progress, I suggest you contact upstream with this report, pointing them at this analysis. Details here: http://guichaz.free.fr/iotop/