System hang on OOM due to missing swap configuration in Ubuntu Asahi (M-series Mac)

[toshithh]

Hi team,

I've encountered a serious stability issue on Ubuntu Asahi running on an Apple Silicon M2 Mac. When system memory is fully used, the machine becomes completely unresponsive — including the power button — and must be hard-rebooted.

After investigation, I found that no swap is configured by default, which likely causes the kernel to deadlock under memory pressure.

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Steps to Reproduce:

• Boot into Ubuntu Asahi on an M2 Mac (mine has 8GB).
• Run memory-intensive applications or simulate high memory usage (stress, browsers, etc.).
• Once RAM is fully consumed, page faults increase rapidly.
• The system freezes entirely — no response to keyboard, mouse, or power button. Only a forced shutdown works.

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Diagnosis:

• free -h

  confirms that no swap is configured.
• Without swap or zram, the kernel has no fallback when memory is exhausted.
• The OOM killer appears unable to recover, resulting in a full system hang.

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Suggested Fixes:

• Enable a default swapfile during installation (e.g., 2–4 GB minimum).
• Or, configure zram (via zram-tools) to provide compressed in-RAM swap, which avoids SSD wear.
• Provide a setup option or install-time prompt for swap configuration.

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System Info:

• Model: MacBook Air M2
• RAM: 8GB
• Kernel: 6.14.0-1001-asahi-arm
• Ubuntu Version: Ubuntu 24.04.2 LTS

[toshithh]

Swap Set-Up with ZRAM-TOOLS

* For reference for anyone looking to set swap post-installation

sudo apt update
sudo apt install zram-tools

/etc/default/zramswap

ALGO=zstd
PERCENT=50

Restart zram.service

sudo systemctl restart zramswap.service

To verify

swapon --show

[tobhe]

Indeed we need to find a nice way to automate this. Introducing it in existing installations is a bit hard because we need to make sure there's enough space available and no swap already configured manually.

[toshithh]

I would be glad to contribute the script for swap. Space would not be an issue when using zram-tools as it would create a block device in the ram itself and also avoid the wear on SSD.
P.S. Great fan of your work

[tobhe]

Thanks, help is always appreciated!

I think we can build on fedora-asahi-remix-scripts which has setup-swap.sh and asahi-setup-swap-firstboot.service.

[toshithh]

I have added the scripts to this repository with instructions.

Also you might need to add zram-tools to extra packages in asahi-desktop.yaml