1
Diagnostic step 1
Collect reproducible test case and kernel oops logs (enable persistent journal, copy /var/crash and dmesg output). Install kdump/crash to capture vmcore for post-mortem analysis.
FULL AI ANALYSIS
Intermittent Linux kernel oops only under heavy memory pressure despite MemTest86 passing
Generated Oct 3, 2026, 12:35:03 AM
Analysis summary
MemTest86 checks raw memory patterns but may not exercise platform-specific memory controller timing, high concurrency, or kernel paths that expose CPU/microcode or chipset issues. The reduction of frequency with an older kernel points toward a kernel regression or a changed scheduler/memory allocator behavior that stresses the platform differently. BIOS/firmware microcode or memory training issues can produce similar intermittent faults that only appear under complex real-world workloads.
Possible causes
A kernel regression or bug in the memory allocator or a driver exposing a null pointer under certain concurrency patterns.
85%CPU microcode or chipset erratum triggered by specific memory access patterns; new BIOS/microcode may be needed.
65%Third-party kernel module or driver (e.g., for VM acceleration or proprietary device) causing instability under load.
55%Memory controller (IMC) timing/training issue or marginal DIMM/slot electrical contact that MemTest did not reproduce.
50%Suggested fixes
2
Diagnostic step 2
Boot with a few kernel command line options to narrow causes: try 'nohz=off', 'slub_debug=FZ', 'threadirqs', or boot with a distribution kernel build (not custom) to compare behavior; check if issue reproduces with a mainline stable kernel.
3
Diagnostic step 3
Test with latest CPU microcode updates (apply vendor microcode package) or try rolling back microcode/BIOS if a recent firmware update coincides with regressions; disable aggressive power/performance BIOS options (PBO, XMP) while testing.
4
Diagnostic step 4
Run workload in a controlled single-CPU affinity (taskset) and repeat to see if specific cores are implicated; run 'stress-ng' and 'memtester' in parallel to replicate workload patterns.
5
Diagnostic step 5
If tests point to kernel-level bug or microcode interaction, open a detailed bug report with kernel mailing list or vendor support including oops logs, kernel version, BIOS revision, and steps to reproduce. For possible hardware failure (if SMART shows errors or further diagnostics indicate faults), escalate to the motherboard/CPU vendor and consider warranty RMA.