Unusable: Crashes when trying to start

[johann-petrak]

Trying to run the nohang-desktop.conf (default) on Ubuntu 24.04.2 LTS

When I check the status:

$ sudo systemctl status nohang-desktop.service
× nohang-desktop.service - Sophisticated low memory handler
     Loaded: loaded (/usr/lib/systemd/system/nohang-desktop.service; enabled; preset: enabled)
     Active: failed (Result: exit-code) since Mon 2025-07-14 16:33:25 CEST; 8s ago
   Duration: 846ms
       Docs: man:nohang(8)
             https://github.com/hakavlad/nohang
    Process: 2599623 ExecStart=/usr/sbin/nohang --monitor --config /etc/nohang/nohang-desktop.conf (code=exited, status=1/FAILURE)
   Main PID: 2599623 (code=exited, status=1/FAILURE)
        CPU: 845ms

Jul 14 16:33:25 zeus systemd[1]: nohang-desktop.service: Scheduled restart job, restart counter is at 5.
Jul 14 16:33:25 zeus systemd[1]: nohang-desktop.service: Start request repeated too quickly.
Jul 14 16:33:25 zeus systemd[1]: nohang-desktop.service: Failed with result 'exit-code'.
Jul 14 16:33:25 zeus systemd[1]: Failed to start nohang-desktop.service - Sophisticated low memory handler.

When checking the log:

$ sudo journalctl -eu nohang-desktop.service 

Jul 14 16:33:24 zeus nohang-desktop[2599623]: NameError: name 'arc_meta_min_index' is not defined. Did you mean: 'arc_meta_used_index'?
Jul 14 16:33:24 zeus nohang-desktop[2599623]: Error in sys.excepthook:
Jul 14 16:33:24 zeus nohang-desktop[2599623]: Traceback (most recent call last):
Jul 14 16:33:24 zeus nohang-desktop[2599623]:   File "/usr/lib/python3/dist-packages/apport_python_hook.py", line 228, in partial_apport_excepthook
Jul 14 16:33:24 zeus nohang-desktop[2599623]:     return apport_excepthook(binary, exc_type, exc_obj, exc_tb)
Jul 14 16:33:24 zeus nohang-desktop[2599623]:            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Jul 14 16:33:24 zeus nohang-desktop[2599623]:   File "/usr/lib/python3/dist-packages/apport_python_hook.py", line 144, in apport_excepthook
Jul 14 16:33:24 zeus nohang-desktop[2599623]:     os.open(pr_filename, os.O_WRONLY | os.O_CREAT | os.O_EXCL, 0o640), "wb"
Jul 14 16:33:24 zeus nohang-desktop[2599623]:     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Jul 14 16:33:24 zeus nohang-desktop[2599623]: OSError: [Errno 30] Read-only file system: '/var/crash/_usr_sbin_nohang.0.crash'
Jul 14 16:33:24 zeus nohang-desktop[2599623]: Original exception was:
Jul 14 16:33:24 zeus nohang-desktop[2599623]: Traceback (most recent call last):
Jul 14 16:33:24 zeus nohang-desktop[2599623]:   File "/usr/sbin/nohang", line 3988, in <module>
Jul 14 16:33:24 zeus nohang-desktop[2599623]:     soft_threshold_min_swap_kb, swap_free, swap_total) = check_mem_swap_ex()
Jul 14 16:33:24 zeus nohang-desktop[2599623]:                                                          ^^^^^^^^^^^^^^^^^^^
Jul 14 16:33:24 zeus nohang-desktop[2599623]:   File "/usr/sbin/nohang", line 1918, in check_mem_swap_ex
Jul 14 16:33:24 zeus nohang-desktop[2599623]:     mem_available, swap_total, swap_free = check_mem_and_swap()
Jul 14 16:33:24 zeus nohang-desktop[2599623]:                                            ^^^^^^^^^^^^^^^^^^^^
Jul 14 16:33:24 zeus nohang-desktop[2599623]:   File "/usr/sbin/nohang", line 1344, in check_mem_and_swap
Jul 14 16:33:24 zeus nohang-desktop[2599623]:     ma += arcstats()
Jul 14 16:33:24 zeus nohang-desktop[2599623]:           ^^^^^^^^^^
Jul 14 16:33:24 zeus nohang-desktop[2599623]:   File "/usr/sbin/nohang", line 183, in arcstats
Jul 14 16:33:24 zeus nohang-desktop[2599623]:     elif n == arc_meta_min_index:
Jul 14 16:33:24 zeus nohang-desktop[2599623]:               ^^^^^^^^^^^^^^^^^^
Jul 14 16:33:24 zeus nohang-desktop[2599623]: NameError: name 'arc_meta_min_index' is not defined. Did you mean: 'arc_meta_used_index'?
Jul 14 16:33:25 zeus systemd[1]: nohang-desktop.service: Main process exited, code=exited, status=1/FAILURE
Jul 14 16:33:25 zeus systemd[1]: nohang-desktop.service: Failed with result 'exit-code'.
Jul 14 16:33:25 zeus systemd[1]: nohang-desktop.service: Scheduled restart job, restart counter is at 5.
Jul 14 16:33:25 zeus systemd[1]: nohang-desktop.service: Start request repeated too quickly.
Jul 14 16:33:25 zeus systemd[1]: nohang-desktop.service: Failed with result 'exit-code'.
Jul 14 16:33:25 zeus systemd[1]: Failed to start nohang-desktop.service - Sophisticated low memory handler.

When I run nohang --version I get:

/usr/sbin/nohang:10: DeprecationWarning: module 'sre_constants' is deprecated
  from sre_constants import error as invalid_re
nohang unknown version

apt install reports nohang to be at version 0.2.0-1.1

[hakavlad]

Thanks for the report!
Is the system installed on ZFS?

[johann-petrak]

Thanks for the report! Is the system installed on ZFS?

The sytem partition is EXT4 on a SSD drive with a swap partition on the same drive. Plus ext4 data partitions on additional hard drives.

[shamnad-sherief]

Thanks for the report! Is the system installed on ZFS?

Same issue here. Log warns on file system. bt using Btrfs

WARNING: ZFS found. Available memory will not be calculated correctly (issue#89)

[hznor]

seems related to #135

[hznor]

@johann-petrak I had the same issue, the Ubuntu package is outdated, building from the master branch was required for me.
Have you tried to build the package from sources like explained here?
https://github.com/hakavlad/nohang?tab=readme-ov-file#to-install-on-debian-and-ubuntu-based-systems

[alexmyczko]

@johann-petrak now ubuntu has an updated version: https://launchpad.net/ubuntu/+source/nohang

[johann-petrak]

Thank you, this appears to indeed be working now!

[johann-petrak]

Sadly nohang does not seem able to report its own version:
nohang --version gives a deprecation error (running python 3.12) and /usr/share/nohang/version is empty.
The Ubuntu package manager reports: 0.2-1.1

[hakavlad]

You can build actual deb
https://github.com/hakavlad/nohang?tab=readme-ov-file#to-install-on-debian-and-ubuntu-based-systems

[alexmyczko]

@johann-petrak you can create a backport easily yourself:

download https://github.com/alexmyczko/autoexec.bat/blob/master/abp
review it, then run abp nohang