Kernel Panic and Node Reboot Loop

Question

A production node repeatedly reboots due to kernel panics under load. Outline your triage and containment steps.

Accepted Answer

When a production node exhibits repeated kernel panics under load, immediate action is required to prevent further instability and data loss. My approach prioritizes isolating the affected system while simultaneously gathering critical data for root cause analysis. Immediately isolate the node from any load balancers, service discovery mechanisms, or scheduler queues to prevent it from receiving new traffic or tasks. Gracefully drain existing workloads to ensure a clean shutdown and minimize potential data corruption. This containment is crucial to stop the cascading failure effect. Configure and trigger a kernel crash dump (kdump) if it's not already active. This involves ensuring the kdump service is properly set up to capture the system's memory state at the time of the panic. Additionally, I'd collect all relevant kernel logs (syslog, dmesg, journalctl) immediately after a reboot or from the last known good state. Investigate recent changes to the kernel or critical drivers on the affected node. This includes reviewing package manager history, deployment logs, and any automated update processes. Simultaneously, I would check hardware health using tools like `smartctl` for disk issues, `memtester` for RAM problems, and review system event logs for any hardware-related errors. Analyze the collected kernel logs and crash dumps for specific error messages, stack traces, or memory corruption signatures. Tools like `addr2line` and `objdump` are invaluable here to correlate addresses in the dump with source code. This systematic analysis helps pinpoint the faulty component or code path. Once a likely root cause is identified, implement a mitigation strategy. This could involve reverting a problematic kernel/driver update, adjusting system tuning parameters, disabling a specific feature, or, if hardware is suspected, initiating a hardware replacement process. After applying the fix, thoroughly test the node under load in a controlled environment before reintroducing it to production. The ultimate goal is to restore stability quickly while ensuring the underlying issue is resolved to prevent recurrence. Proactive monitoring of system health, resource utilization, and change logs is paramount for identifying potential problems before they impact production.

Kernel Panic and Node Reboot Loop

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