Tangential, but does anyone know why in 2026 and on Debian 13, my machine still hangs when some process exhausts RAM?

Is there really no higher-priority kernel process to prevent total freeze of the system and send a SIGKILL to the culprit process when such a scenario happens?

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afishhh an hour ago | parent | next [-]

Set `/sys/kernel/mm/lru_gen/min_ttl_ms` at boot (see https://docs.kernel.org/admin-guide/mm/multigen_lru.html).

User-space OOM killers never really worked for me and imo are not a proper solution anyway. This option instead lets you make the kernel OOM killer actually work for desktop use.

Currently have it set to `1000` and it works very well for me (don't remember the last time I had a full system freeze due to OOM).

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dev_hugepages 2 hours ago | parent | prev | next [-]

This is called an oomkiller. The kernel has one but it kicks in very late and the kernel prefers to do page trashing instead of killing processes.

systemd-oomd should be integrated in systemd, you can configure it to your liking and see if it improves your problem.

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ButlerianJihad an hour ago | parent [-]

I believe that you mean: https://en.wikipedia.org/wiki/Thrashing_(computer_science)

Chris Siebenmann discusses when the OOM killer triggers: https://utcc.utoronto.ca/~cks/space/blog/linux/OOMKillerWhen

Chris disables systemd-oomd after it obliterates his X session with no explanation: https://utcc.utoronto.ca/~cks/space/blog/linux/SystemdOomdNo...

	▲	rovr138 an hour ago \| parent [-]
		> First off, this is exactly how systemd-oomd is supposed to behave under memory pressure. The documentation is specific on this; systemd-oomd itself says: > > [...] If the configured limits are exceeded, systemd-oomd will select a cgroup to terminate, and send SIGKILL to all processes in it. [...] > By having the user@.service template be enrolled in systemd-oomd, Fedora made the cgroup that systemd-oomd would select to be killed be all of your processes (across all of your sessions, if you have more than one). ... Maybe Fedora has fixed or improved in the last 4 years. Or maybe they don't run Fedora.

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negrel 2 hours ago | parent | prev | next [-]

OS are designed to fully exploit available resources, Linux tries its best before triggering an OOM kill.

I recommend using the earlyoom if you want more aggresive oom kill:

https://github.com/rfjakob/earlyoom

The README contains a lot of interesting information.

	▲	oomedfornight an hour ago \| parent [-]
		A strange behavior I sometimes run into with earlyoom is that I try to start up some buggy software of mine and it seemingly never starts. It took a long evening to figure out that it gets earlyoom'd immediately because it tries to allocate too much. Previously the very familiar hitching and freezing was a very easy sign of what kind of issue I was dealing with

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fc417fc802 an hour ago | parent | prev | next [-]

> does anyone know why

In a nutshell, overcommit. It's more or less broken by design but it's also incredibly practical so pretty much everyone does it.

Couple that with the fact that it's difficult bordering on impossible to correctly determine the culprit. If you've got 16 GB RAM and the user launches 3 processes each of which attempts to use 8 GB who should you kill?

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wongarsu an hour ago | parent [-]

Notably windows doesn't use overcommit, and degrades much more gracefully under memory pressure. The biggest tradeoff is the amount of disk space consumed by a page file that also has to reserve space for unused pages that have been allocated but never been swapped in. On linux you can turn overcommit off, but there's too much software written around the assumption that overcommit is on

	▲	fc417fc802 an hour ago \| parent [-]
		Is that still the case today? Notably (IIUC) overcommit is required for certain security measures. I believe it was chromium that I noticed mmaping somewhere north of 1 TB of memory on startup so that it can do (again IIUC) something akin to ASLR internally.

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BoredomIsFun an hour ago | parent | prev | next [-]

It does not if you switch swapp off and use zram instead. I am typing right now on such a setup wityh 16 GiB ram and it occasionally, once a week or so, kills my firefox due to oom.

If you are you using disk swap - not sure why would if you have a SSD, but I once heard some justification for doing that - then install early OOM.

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pndc an hour ago | parent | prev | next [-]

I had a 1GB Debian VM which started freezing (requiring a hard reboot) after a routine aptitude upgrade to apply security patches. It was indeed caused by low memory, but not out of memory as there was still enough swap space remaining.

The culprit turned out to be the kernel itself, and rolling back to a 6.1 series kernel made the problem go away. I see that Linus's love for vibe-coding is already paying dividends.

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CoastalCoder an hour ago | parent | prev | next [-]

Just mentioning this in case it's helpful:

If you know ahead of time which programs / processes are at risk of unacceptably high memory usage, check out "ulimit".

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trompetenaccoun an hour ago | parent | prev | next [-]

This has finally been fixed in the latest Ubuntu version (26), it now force closes the culprit.

	▲	jillesvangurp 37 minutes ago \| parent [-]
		Ah nice. I was dealing with that in one of our environments where a security update ended up causing apt to use more memory than usual so the oom killer nuked our elasticsearch process to "free up some memory". And since that happened on all nodes around the same time, it took out the entire cluster. If you are not familiar, random, uncontrolled node restarts in any kind of multi node database or search product are a great way to trigger outages. So, not great. I've had quite a few encounters with the oomkiller killing processes that were important and didn't need killing. Or as I like to phrase it "killing the one reason this server exists". These days the way to size a server is "have enough memory to run whatever you need running + at least half a GB for whatever apt might randomly demand at any point". And guess what, memory tends to be expensive in cloud environments so people tend to get vms with as little as half a GB of ram.

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elektrontamer 2 hours ago | parent | prev | next [-]

I always install earlyoom for that reason

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pestatije an hour ago | parent | prev [-]

not tangential at all...try setting up a swap partition

	▲	jenders an hour ago \| parent [-]
		Triggered