NVRM: Xid 31, MMU Fault: ENGINE GRAPHICS GPCCLIENT FAULT_PDE

GPU MMU page fault (Xid 31), often an NVLS/Fabric Manager cascade. This entry explains how to confirm the cause, apply the fix, and separate it from adjacent xid failures.

The literal signature is "NVRM: Xid 31, MMU Fault: ENGINE GRAPHICS GPCCLIENT FAULT_PDE". It is a hardware failure associated with NVIDIA data center GPUs and the Linux driver. The line identifies the failing operation or subsystem, while the surrounding evidence decides whether it is the initiating fault or a downstream symptom.

GPU MMU page fault (Xid 31), often an NVLS/Fabric Manager cascade. The failure becomes visible at this call site because the operation first requires the missing resource, valid state, healthy peer, or correct result. Earlier log lines and a known-good control carry more causal value than the final wrapper exception.

• The workload stops or loses forward progress after emitting "NVRM: Xid 31, MMU Fault: ENGINE GRAPHICS GPCCLIENT FAULT_PDE".
• A retry on the same configuration reproduces the failure because the causal state has not changed.
• The outer framework exception can hide the rank, node, allocation, or dependency that failed first.
• Increasing timeouts or reducing workload size can suppress the symptom without correcting the cause.

• NVIDIA data center GPUs and the Linux driver
• production-shaped multi-accelerator workloads
• containerized and bare-metal deployments of the same stack

Apply the following checklist to a small reproduction: each box below is a positive signal that you are looking at this exact failure rather than a sibling in the same taxonomy.

• ✓Find the first occurrence of "NVRM: Xid 31, MMU Fault: ENGINE GRAPHICS GPCCLIENT FAULT_PDE" and preserve at least 100 lines before it.
• ✓Identify which rank, node, device, or process emitted the first related warning.
• ✓Compare the failing rank, node, input, or configuration with one known-good control.
• ✓Repeat the same input after the targeted change and require the signature to disappear.
• ✓Resume from latest checkpoint only after the control passes.

NVRM: Xid 31, MMU Fault: ENGINE GRAPHICS GPCCLIENT FAULT_PDE

Timestamps and exact values vary across runs, but the pattern. An info-level start, an early WARN, an ERROR carrying the symptom. Is the actual fingerprint you should alert on. The Denpex platform flags this combination automatically.

Stop nvidia-fabricmanager, run nvidia-smi --gpu-reset, then restart fabricmanager; reboot if it persists. Never restart Fabric Manager under load. This changes the condition in the causal diagnosis instead of hiding the outer exception. The repeated control proves ownership before recovery from latest checkpoint.

# Preserve evidence before restarting
dmesg -T | grep -iE 'NVRM|Xid|AER|NVLink|ECC'
nvidia-smi -q
dcgmi diag -r 3

# Find the exact signature in the complete log
rg -n -F -- "NVRM: Xid 31, MMU Fault: ENGINE GRAPHICS GPCCLIENT FAULT_PDE" <log-file>

Adapt the snippet to your framework. The same pattern holds for PyTorch Lightning, Hugging Face Trainer, DeepSpeed, Megatron-LM, and vLLM training wrappers. Where the wrapper exposes a config flag (for examplelr_scheduler_type in Trainer), prefer the flag over the imperative API to keep the schedule declarative and reproducible.

Xid 31 is one of a small set of codes the NVIDIA driver uses to report GPU faults, and the number is most of the diagnosis: it tells you whether you are looking at your own code, the driver, or a board that needs replacing.

Select the traceback or open the failed terminal, then run Denpex locally to see the initiating rank, collateral failures, exact fix, and verification command without uploading the log.

• GPU MMU page fault (Xid 31), often an NVLS/Fabric Manager cascade.
• The decisive evidence is the first log line that precedes "NVRM: Xid 31, MMU Fault: ENGINE GRAPHICS GPCCLIENT FAULT_PDE" and differs from a healthy run.
• A nearby failure remains a competing hypothesis until a control separates configuration, capacity, transport, and hardware causes.