CentOS Stream 10 – Common Problem 059 – 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

Rootless `podman run` aborts with `cannot setup namespace: cannot allocate memory` or uidmap errors.

Environment & Reproduction

Triggered when subuid and subgid ranges are missing or too small for the user.

Root Cause Analysis

Insufficient sub-UID allocation prevents user namespace creation for rootless containers.

Quick Triage

Inspect `/etc/subuid` and `/etc/subgid` and current `podman info`.

Step-by-Step Diagnosis

Confirm the allocated range covers the required UID/GID space (at least 65536).

Solution – Primary Fix

Add entries with `usermod –add-subuids 100000-165535 user` and run `podman system migrate`.

Solution – Alternative Approaches

Run the workload rootful as a fallback or use `quadlet` system units.

Verification & Acceptance Criteria

Container starts under user namespace and `podman top` shows mapped UID.

Rollback Plan

Restore prior subuid/subgid files if existing rootless workloads break.

Prevention & Hardening

Provision subuid ranges via configuration management for every user.

Related Errors & Cross-Refs

Linked to cgroup v2 delegation and storage driver configuration issues.

Related tutorial: View the step-by-step tutorial for centos-stream-10.

View all centos-stream-10 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

podman rootless reference for CentOS Stream 10.