proc_pid_oom_score_adj(5)

🌸 proc_pid_oom_score_adj — the oom_score_adj file, bestie edition 🌸

okay so this is a page from section 5 of the Linux man-pages — <rainbow>proc_pid_oom_score_adj(5)</rainbow>, aka the File Formats Manual — and it's all about that one little procfile that decides who gets 💀'd when your RAM runs out. sit down, hydrate, let's go.

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✨ NAME ✨

/proc/pid/oom_score_adj — OOM-killer score adjustment 💅

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🫶 DESCRIPTION 🫶

/proc/pid/oom_score_adj</p> (since Linux 2.6.36)

This file is your lil' dial for tuning the badness heuristic — the thing the kernel uses to pick which process gets murdered when you run out of memory. out-of-memory conditions, killed process, you know the vibe 😭

So the badness heuristic gives every candidate task a value from 0 (never kill) all the way up to 1000 (always kill), and that's how it decides who's the target. The units are roughly a proportion along that range of allowed memory the process may allocate from, based on an estimation of its current memory and swap use. like, if a task is using all of its allowed memory, its badness score is 1000. Using half of its allowed memory? Score is 500. simple math, slay ✨

There's also an extra lil' factor baked into the badness score: root processes get 3% extra memory over other tasks. nepotism, honestly 🙈

The amount of "allowed" memory depends on the context in which the OOM-killer was called:

• if it's because the memory assigned to the allocating task's cpuset is exhausted, the allowed memory represents the set of mems assigned to that cpuset (see cpuset(7)) 🎀
• if it's because a mempolicy's node(s) are exhausted, the allowed memory represents the set of mempolicy nodes
• if it's because a memory limit (or swap limit) was reached, the allowed memory is that configured limit
• and finally, if it's because the entire system is out of memory, the allowed memory represents all allocatable resources 🌈

The value of oom_score_adj gets added to the badness score before it's used to figure out which task to kill. Acceptable values range from -1000 (OOM_SCORE_ADJ_MIN) to +1000 (OOM_SCORE_ADJ_MAX). This is how user space gets to control the preference for OOM-killing, ranging from always preferring a certain task all the way to completely disabling it from OOM-killing. And the lowest possible value, -1000, is basically equivalent to disabling OOM-killing entirely for that task, since it will always report a badness score of 0. it's giving "protected by the universe" energy 👑

Consequently, it is very simple for user space to define the amount of memory to consider for each task. Setting an oom_score_adj value of +500, for example, is roughly equivalent to allowing the remainder of tasks sharing the same system, cpuset, mempolicy, or memory controller resources to use at least 50% more memory. A value of -500, on the other hand, would be roughly equivalent to discounting 50% of the task's allowed memory from being considered as scoring against the task. maths girlies rise 🧚

For backward compatibility with previous kernels, /proc/pid/oom_adj can still be used to tune the badness score — its value is scaled linearly with oom_score_adj 🦋

Writing to /proc/pid/oom_score_adj or /proc/pid/oom_adj will change the other with its scaled value. they're linked, they're a package deal, no cap 💖

Also!! The choom(1) program provides a command-line interface for adjusting the oom_score_adj value of a running process or a newly executed command. use it, it's iconic.

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💜 HISTORY 💜

/proc/pid/oom_adj (since Linux 2.6.11)

This file can be used to adjust the score used to select which process should be killed in an out-of-memory (OOM) situation. The kernel uses this value for a bit-shift operation of the process's oom_score value: valid values are in the range -16 to +15, plus the special value -17, which disables OOM-killing altogether for this process. A positive score increases the likelihood of this process being killed by the OOM-killer; a negative score decreases it. 💅

The default value for this file is 0; a new process inherits its parent's oom_adj setting. A process must be privileged (CAP_SYS_RESOURCE) to update this file, although a process can always increase its own oom_adj setting (since Linux 2.6.20). glow-up privileges, iykyk ✨

Since Linux 2.6.36, use of this file is deprecated in favor of /proc/pid/oom_score_adj, and it was finally removed in Linux 3.7.

⚠️ bestie listen: deprecated means deprecated, and removed means gone. don't be out here writing to /proc/pid/oom_adj on a modern kernel and acting surprised. 💀

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👀 SEE ALSO 👀

• proc(5)
• proc_pid_oom_score(5)

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okayyy that's the whole page, you understood all of it, I'm so proud 🥹 go forth and tune your badness scores responsibly, mwah 💅

this lil' rewrite was based on Linux man-pages 6.20, dated 2026-02-08 — that's the source and the version, and also the date, all in one cute sign-off. bye bestie 🎀🌸✨