FreeBSD 12 – Common Problem 025 – Kernel Panic Triggered by Faulty Third-Party Driver

📖 ~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

System crashes repeatedly, causing service downtime and potential data corruption.

Environment & Reproduction

Panic occurs shortly after boot or device activity following driver update.

Root Cause Analysis

Out-of-tree module bug or incompatibility with current kernel patch level.

Quick Triage

Capture panic context and loaded modules.

sysctl debug.kdb.panic
kldstat
ls /var/crash

Step-by-Step Diagnosis

Analyze vmcore and identify faulting module path.

kgdb /boot/kernel/kernel /var/crash/vmcore.0
bt
dmesg -a | tail -n 150

Solution – Primary Fix

Disable offending module from boot and install compatible version.

sysrc kld_list-=' badmodule'
rm -f /boot/modules/badmodule.ko
reboot

Solution – Alternative Approaches

Boot previous kernel from loader menu and defer update until vendor patch is verified.

Verification & Acceptance Criteria

System runs through soak window without panic and required hardware remains operational.

Rollback Plan

Re-enable prior stable module/kernel combo if replacement introduces new regressions.

Prevention & Hardening

Test third-party modules in staging, keep crashdump enabled, and gate rollout by canary hosts.

Related Errors & Cross-Refs

`panic: page fault`, `Fatal trap`, module-specific call trace in vmcore.

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

View all freebsd-12 tutorials on the Tutorials Hub →

Browse all common problems & solutions on the Tutorials Hub.

References & Further Reading

`kgdb(1)`, FreeBSD crash dump analysis guide, vendor driver release notes.