🔴 Critical   ⏱ 5–30 min  Last verified: 20 May 2026
Affected versions: RHEL 10.0 RHEL 10.1

📖 ~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

Post-crash root-cause analysis is blocked because vmcore files are absent.

Environment & Reproduction

Systems with kdump installed but crashkernel memory not reserved.

systemctl status kdump
cat /proc/cmdline | tr ' ' '
' | grep crashkernel

Root Cause Analysis

Crash kernel reservation or kdump target path is misconfigured.

Quick Triage

Confirm crashkernel parameter and kdump target accessibility.

kdumpctl showmem
grep -E 'path|core_collector' /etc/kdump.conf

Step-by-Step Diagnosis

Run kdump sanity checks and inspect service logs.

kdumpctl test
journalctl -u kdump -n 200 --no-pager
Illustrative mockup for rhel-10 — kdump_missing_vmcore
Crash occurred without vmcore — Illustrative mockup — Progressive Robot

Solution – Primary Fix

Set crashkernel on boot cmdline and restart kdump service.

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grubby --update-kernel=ALL --args='crashkernel=auto'
systemctl enable --now kdump
reboot
Illustrative mockup for rhel-10 — kdump_vmcore_created
vmcore captured successfully — Illustrative mockup — Progressive Robot

Solution – Alternative Approaches

Store vmcore on dedicated remote target to avoid local disk limits.

vi /etc/kdump.conf
systemctl restart kdump

Verification & Acceptance Criteria

kdumpctl status is ready and test dump path is writable.

kdumpctl status
ls -ld /var/crash

Rollback Plan

Remove crashkernel argument if memory pressure affects critical workloads.

grubby --update-kernel=ALL --remove-args='crashkernel=auto'

Prevention & Hardening

Audit kdump readiness after every kernel update.

rpm -q kexec-tools
kdumpctl status

No crashkernel parameter, kdump service inactive, vmcore missing.

Related tutorial: View the step-by-step tutorial for rhel-10.

View all rhel-10 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

kdump configuration and kernel crash analysis workflow.

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