Ubuntu 24.04 LTS OOM Kills Increase After Swap Disabled

📖 ~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

Memory pressure triggers OOM kills, causing service crashes and instability.

Environment & Reproduction

Observed after swapoff changes on memory-constrained hosts.

free -h

Root Cause Analysis

No swap headroom exists for transient memory spikes and reclaim behavior.

Quick Triage

Check swap status and recent OOM events.

swapon --show && dmesg | grep -i 'Out of memory'

Step-by-Step Diagnosis

Review vm settings and per-service memory peaks.

sysctl vm.swappiness vm.overcommit_memory && sudo journalctl -k --since -2h

Solution – Primary Fix

Create and enable swapfile with secure permissions.

sudo fallocate -l 4G /swapfile && sudo chmod 600 /swapfile && sudo mkswap /swapfile && sudo swapon /swapfile

Solution – Alternative Approaches

Scale memory allocation or tune service limits to reduce peak usage.

Verification & Acceptance Criteria

Swap is active and OOM kill events no longer appear under expected load.

Rollback Plan

Disable and remove swapfile if policy forbids swap usage.

Prevention & Hardening

Establish memory alert thresholds and capacity planning baselines.

Related Errors & Cross-Refs

Related to cgroup memory limit hits and abrupt process terminations.

Related tutorial: View the step-by-step tutorial for Ubuntu 24.04 LTS.

View all Ubuntu 24.04 LTS tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Ubuntu swap management and Linux OOM behavior references.