🟠 High   ⏱ 5–30 min  Last verified: 20 May 2026
Affected versions: Debian 12

📖 ~1 min read

Table of contents
  1. Symptom & Impact
  2. Environment & Reproduction
  3. Root Cause Analysis
  4. Quick Triage
  5. Step-by-Step Diagnosis
  6. Solution – Primary Fix
  7. Solution – Alternative Approaches
  8. Verification & Acceptance Criteria
  9. Rollback Plan
  10. Prevention & Hardening
  11. Related Errors & Cross-Refs
  12. References & Further Reading

Symptom & Impact

Applications terminate unexpectedly as kernel OOM killer reclaims memory.

Environment & Reproduction

Typical during traffic bursts, memory leaks, or undersized VM allocations.

cat /etc/os-release
free -h
dmesg | grep -i 'killed process'

Root Cause Analysis

Total memory pressure exceeds available RAM and swap capacity.

Quick Triage

Identify top memory consumers and recent OOM events.

ps -eo pid,cmd,%mem,rss --sort=-%mem | head
journalctl -k | grep -i oom | tail -n 50

Step-by-Step Diagnosis

Measure trend growth and confirm whether leak is process-specific.

vmstat 1 10
pmap -x PID | tail -n 1
cat /proc/meminfo
Illustrative mockup for debian-12 — terminal_or_shell
Diagnostic output for performance/oom-killer — Illustrative mockup — Progressive Robot

Solution – Primary Fix

Add swap, tune service memory limits, and restart leaking services.

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sudo fallocate -l 4G /swapfile
sudo chmod 600 /swapfile
sudo mkswap /swapfile && sudo swapon /swapfile
sudo systemctl restart SERVICE
Illustrative mockup for debian-12 — log_or_config
Resolution output for performance/oom-killer — Illustrative mockup — Progressive Robot

Solution – Alternative Approaches

Scale memory resources or split workload tiers.

sudo systemctl set-property SERVICE MemoryMax=2G

Verification & Acceptance Criteria

No new OOM events and memory headroom remains stable.

free -h
swapon --show
journalctl -k | grep -i oom | tail

Rollback Plan

Disable temporary swap file if it impacts IO performance goals.

sudo swapoff /swapfile
sudo rm -f /swapfile

Prevention & Hardening

Add memory monitoring and enforce application-level limits.

systemctl show SERVICE -p MemoryCurrent,MemoryMax

Related logs include out of memory kill process and memory cgroup out of memory.

Related tutorial: View the step-by-step tutorial for Debian 12.

View all Debian 12 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Linux OOM behavior and Debian memory management guidance.

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