CentOS Stream 9 – Common Problem 063 – Diagnosis and Fix

📖 ~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

Critical processes are killed and dmesg shows oom-killer entries.

Environment & Reproduction

Memory leak, high page cache pressure, or undersized swap.

Root Cause Analysis

Demand exceeds RAM+swap and oom_score selects a key process.

Quick Triage

Check `dmesg -T | grep -i oom` and `journalctl -k`.

Step-by-Step Diagnosis

Use `top`, `free -h`, and `vmstat 1` to find pressure sources.

Solution – Primary Fix

Adjust `oom_score_adj` for critical services via systemd `OOMScoreAdjust=`.

Solution – Alternative Approaches

Add swap or memory; tune `vm.swappiness`.

Verification & Acceptance Criteria

No further oom-killer events; services stable under load.

Rollback Plan

Restart killed services and verify their dependencies.

Prevention & Hardening

Capacity plan with `sar` and Grafana; set alerts on memory.

Automate patch management and compliance across your fleet with our DevOps services.

Related Errors & Cross-Refs

Pairs with cgroup memory limits and HugePages misconfig.

Related tutorial: View the step-by-step tutorial for centos-stream-9.

View all centos-stream-9 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

Kernel OOM documentation and earlyoom tooling.