Public bug reported:
The internal display brightness is reset to maximum after every reboot.
Brightness control itself works normally after login.
System information:
- OS: Ubuntu 26.04 LTS
- Laptop: Lenovo Legion Y9000P IAX10 2025
- GPU: NVIDIA GeForce RTX 5060 laptop
- GPU mode: discrete GPU only
- Desktop: GNOME 50, Wayland
- NVIDIA driver: nvidia-driver-595-open (595.71.05-0ubuntu0.26.04.1)
- Backlight device:
only /sys/class/backlight/nvidia_0 exists.
(Output of:
ls /sys/class/backlight
is:
nvidia_0)
Problem:
After reboot, the internal display brightness always comes back at maximum
brightness.
The brightness keys work correctly after login, and the value in:
/sys/class/backlight/nvidia_0/brightness
changes correctly when adjusting brightness manually.
However, systemd does not restore the previously saved brightness on boot.
Relevant journal errors from:
journalctl -b -p err..alert
include:
kernel: KHO: Failed to reserve lowmem scratch buffer
systemd[1]: systemd-backlight@backlight:nvidia_0.service: Found ordering cycle:
nvidia-persistenced.service/start after basic.target/start after
sockets.target/start after systemd-logind-varlink.socket/start after
systemd-backlight@backlight:nvidia_0.service/start
systemd[1]: systemd-backlight@backlight:nvidia_0.service: Unable to break cycle
starting with systemd-backlight@backlight:nvidia_0.service/start
The relevant issue appears to be the ordering cycle between:
systemd-backlight@backlight:nvidia_0.service
and:
nvidia-persistenced.service
On this system, nvidia-persistenced.service is a static unit, and it is active.
It cannot be disabled with:
sudo systemctl disable --now nvidia-persistenced.service
because systemctl reports:
The unit files have no installation config (WantedBy=, RequiredBy=, UpheldBy=,
Also=, or Alias= settings in the [Install] section…)
This means they are not meant to be enabled or disabled using systemctl.
Workaround:
Masking nvidia-persistenced.service fixes the brightness restore issue:
sudo systemctl mask nvidia-persistenced.service
After masking nvidia-persistenced.service and rebooting, the system
starts normally and the internal display brightness is no longer reset
to maximum. The brightness value is restored correctly.
Expected behavior:
The previous brightness value for /sys/class/backlight/nvidia_0 should be
restored on boot by systemd-backlight.
Actual behavior:
Brightness is reset to maximum after every reboot.
The journal shows an ordering cycle involving systemd-
backlight@backlight:nvidia_0.service and nvidia-persistenced.service.
Additional notes:
This system is running in discrete GPU only mode, so the only available
backlight device is nvidia_0. There is no intel_backlight or acpi_video0
backlight device.
I am not sure whether this should be fixed in the NVIDIA service unit
ordering, Ubuntu NVIDIA driver packaging, or systemd-backlight
integration. However, masking nvidia-persistenced.service works around
the problem, which strongly suggests that nvidia-persistenced.service is
involved in preventing systemd-backlight from restoring nvidia_0
brightness correctly.
English is not my native language, so I used translation tools to help
write this issue.Some wording may be inaccurate.
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: nvidia-driver-595-open 595.71.05-0ubuntu0.26.04.1
ProcVersionSignature: Ubuntu 7.0.0-22.22-generic 7.0.0
Uname: Linux 7.0.0-22-generic x86_64
ApportVersion: 2.34.0-0ubuntu2
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Tue Jun 9 09:33:45 2026
InstallationDate: Installed on 2026-06-07 (2 days ago)
InstallationMedia: Ubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423.1)
ProcEnviron:
LANG=zh_CN.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
XDG_RUNTIME_DIR=<set>
SourcePackage: nvidia-graphics-drivers-595
UpgradeStatus: No upgrade log present (probably fresh install)
** Affects: nvidia-graphics-drivers-595 (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute wayland-session
--
You received this bug notification because you are a member of Ubuntu
Bugs, which is subscribed to Ubuntu.
https://bugs.launchpad.net/bugs/2155990
Title:
Internal display brightness is reset to maximum after reboot due to
ordering cycle between systemd-backlight@nvidia_0 and nvidia-
persistenced
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/nvidia-graphics-drivers-595/+bug/2155990/+subscriptions
--
ubuntu-bugs mailing list
[email protected]
https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
