Failed Shutdown or Reboot Due to ZRAM Unmount Failure

[Anifyuli]

Hi CachyOS kernel maintainers,

I’d like to report a recurring issue that I’ve encountered since kernel version 6.15.1, which still persists in 6.15.2 — though it occurs intermittently.

My system sometimes fails to shut down or reboot properly due to a failure in unmounting ZRAM devices. However, systemd still reports that the shutdown process completes successfully. I managed to capture a screenshot from Plymouth’s verbose mode (accessed by pressing the Esc key), shown below:

Since the issue doesn’t occur consistently, I haven’t been able to reliably reproduce it. Do you have any idea what might be causing this or how I can fix it?

Thank you!

[andersrh]

Hello. do you still experience this?
I used to have issue when my system was hibernating but I havent experienced that issue for a while now.

[Anifyuli]

Hello. do you still experience this?

In my device isn't not appear again after create a service for disable ZRam before shutdown, reboot, or halt. In my friend device is still appear (but with different distro, he use NixOS and add CachyOS kernel from Chaotic Nyx)

[PavelDobCZ23]

I can confirm this occuring on my system as well. I'm on Arch using the CachyOS kernel from the repo.

[Anifyuli]

I create systemd service for avoid this issue can happen again on my system, like this

[Unit]
Description=Disable ZRam devices created by zram-generator
After=multi-user.target
DefaultDependencies=no
Conflicts=shutdown.target reboot.target halt.target

[Service]
Type=oneshot
RemainAfterExit=yes
ExecStart=/bin/true
ExecStop=/bin/sh -c 'for dev in /dev/zram*; do [ -b "$dev" ] && swapoff "$dev" 2>/dev/null || true; done'
TimeoutStopSec=30

[Install]
WantedBy=multi-user.target

[mikaeldui]

@Anifyuli just to confirm, are you running CachyOS or Fedora with the CachyOS kernel?

[Anifyuli]

@Anifyuli just to confirm, are you running CachyOS or Fedora with the CachyOS kernel?

I use CachyOS kernel on Fedora

[mikaeldui]

@Anifyuli just to confirm, are you running CachyOS or Fedora with the CachyOS kernel?

I use CachyOS kernel on Fedora

Do you have cachyos-settings installed? It has its own zram-generator-defaults.

Have you tried repairing Grub? It was mentioned here as a fix.

I noticed that if I disable write cache on my raid controller the issue seems to disappear source

Do you happen to have a swap partition in addition to the ZRAM? nefelim4ag/systemd-swap#199

Does lsof | grep /dev/zram show any output? For me there's nothing.

Also, why are there so many zram devices? I only have zram0.

[Anifyuli]

Also, why are there so many zram devices? I only have zram0.

I have many ZRam blocks (I create 4 Zram blocks using systemd-zram-generator) for make my ZRam more efficient to preventing OOM situation. In my prev experiences and experiments, multiple ZRam block make my system can maximize it usage in high workloads and more CPU compression utilization. This is my configuration.

$ cat /etc/systemd/zram-generator.conf
# This config file enables a /dev/zram0 device with the default settings:
# — size — same as available RAM or 8GB, whichever is less
# — compression — most likely lzo-rle
#
# To disable, uninstall zram-generator-defaults or create empty
# /etc/systemd/zram-generator.conf file.

[zram0]
zram-size = max(ram / 4, 2048)
compression-algorithm = zstd

[zram1]
zram-size = max(ram / 4, 2048)
compression-algorithm = zstd

[zram2]
zram-size = max(ram / 4, 2048)
compression-algorithm = zstd

[zram3]
zram-size = max(ram / 4, 2048)
compression-algorithm = zstd

@mikaeldui, I install too cachyos-settings but I don't know how to use it, I think it just bunch of sysctlconfigs

dnf list --installed | grep cachyos-settings
cachyos-settings.x86_64                              1.2.5-1.fc42                        copr:copr.fedorainfracloud.org:bieszczaders:kernel-cachyos-addons

[Anifyuli]

I try to copying zram-generator config from here and I disable my Zram disable service. I'll reporting again if this problem appear again