DataLoader worker is killed by signal: Bus error shared memory exhausted

PyTorch DataLoader uses shared memory (/dev/shm) to pass tensors to the main process. K8s defaults /dev/shm to 64MB. When data is large, this fills up rapidly, leading to Bus error or Pod OOMKilled. This entry explains how to confirm the cause, apply the fix, and separate it from adjacent storage failures.

The literal signature is "DataLoader worker is killed by signal: Bus error shared memory exhausted". It is a data pipeline failure associated with data loaders, GPU Direct Storage, and network filesystems. The line identifies the failing operation or subsystem, while the surrounding evidence decides whether it is the initiating fault or a downstream symptom.

PyTorch DataLoader uses shared memory (/dev/shm) to pass tensors to the main process. K8s defaults /dev/shm to 64MB. When data is large, this fills up rapidly, leading to Bus error or Pod OOMKilled. 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 "DataLoader worker is killed by signal: Bus error shared memory exhausted".
• 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.

• data loaders, GPU Direct Storage, and network filesystems
• 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 "DataLoader worker is killed by signal: Bus error shared memory exhausted" 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 restart pod with updated volume spec only after the control passes.

DataLoader worker is killed by signal: Bus error shared memory exhausted

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.

Mount an emptyDir volume with medium: Memory to /dev/shm to increase the shared memory size, and increase pod memory requests/limits accordingly. This changes the condition in the causal diagnosis instead of hiding the outer exception. The repeated control proves ownership before recovery from restart pod with updated volume spec.

# Preserve evidence before restarting
rg -n -i 'error|exception|timeout|failed' <log-file>
nvidia-smi
python -m torch.utils.collect_env

# Find the exact signature in the complete log
rg -n -F -- "DataLoader worker is killed by signal: Bus error shared memory exhausted" <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.

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.

• PyTorch DataLoader uses shared memory (/dev/shm) to pass tensors to the main process. K8s defaults /dev/shm to 64MB. When data is large, this fills up rapidly, leading to Bus error or Pod OOMKilled.
• The decisive evidence is the first log line that precedes "DataLoader worker is killed by signal: Bus error shared memory exhausted" and differs from a healthy run.
• A nearby failure remains a competing hypothesis until a control separates configuration, capacity, transport, and hardware causes.