What does this failure look like in production?

In production this failure typically appears during the first tens-to-hundreds of training steps: loss curves become non-monotonic, validation metrics plateau above the baseline, and downstream checkpoints either diverge or fail to improve. Engineers frequently misread it as data drift when the underlying mechanism is a memory-mapped checkpoint file was truncated or deleted while the process still had it mapped, causing sigbus when the process tries to read the missing pages. Validating against the symptom list in this entry is the fastest way to confirm the diagnosis.

Is this a hardware or a software issue?

Data Integrity failures can look like either layer depending on the symptom. The discriminator is the resolution of the symptom to the recommended fix: if applying the steps under "How to fix it" eliminates the symptom, this is a software/configuration class issue regardless of the hardware it surfaced on. Repeat the fix on a fresh node to confirm.

How long does the fix typically take?

Most resolutions from this entry take 10 to 30 minutes of engineer time once the diagnosis is confirmed. Long fixes come from skipping the diagnosis step and chasing apparent symptoms (validation drift, memory growth, slow throughput) instead of the actual root cause listed above. Apply the fix in a small experiment first, then roll it forward.

Does this affect inference or only training?

Primarily this is a data integrity failure observed during training, but the same misconfiguration can leak into downstream evaluation and serving. Treat the prevention checklist as a guardrail: any pipeline that touches a trained checkpoint should re-validate the failure mode before promoting the model.

What's the cheapest way to confirm this is the problem?

Cheapest signal: reproduce the symptom on a 1-GPU toy run with the same configuration. If the toy run exhibits the same behavior, the cause is the configuration rather than the cluster. If only the multi-GPU run is affected, the failure is a distributed interaction, so Training with memory-mapped checkpoint files on NFS is the most likely layer to inspect.

Can the Denpex platform detect this automatically?

Yes. Denpex correlates the symptoms in this entry against your training logs in real time and surfaces the failure taxonomy, root cause, and exact remediation command on the console. Three full diagnoses are included free during signup, and the encyclopedia entry you are reading is generated from the same signal library that powers the platform.

What related failures should I check next?

Closely related failures cluster around #deepspeed, #sigbus, #exit-code-7. After applying this fix, validate against the related entries below to confirm no overlapping cause is masking as this one. Engineers routinely discover that the dominant failure mode is actually a second, sibling failure compounded on top.

Will this recur after the fix?

Applied once with the prevention checklist, this failure does not recur under normal operation. The recurring variant most engineers encounter is the re-emergence of the same symptom on a different model or stack after deepspeed is upgraded. Pin compatible versions and rerun the prevention smoke test on every dependency change.

Is there a fingerprint I can monitor?

Yes. Process exits with code -7 (SIGBUS) or signal 7 is the highest-signal fingerprint. Wire a metric or alert on that signal (or its absence after the fix) so you can detect the recurrence automatically. The Denpex platform encodes this exact fingerprint and surfaces it directly in the dashboard.

What is the official documentation that covers this?

Reference documentation is listed in the References section at the bottom of this entry. The most authoritative URLs are the upstream framework docs and the issue trackers cited; the Denpex entry synthesizes both into the executive, engineer, and on-call perspectives so each audience can act without reading every linked source.

Does this entry include working code?

Yes. The "Code Examples" section contains copy-paste-ready snippets that target the most common stacks (PyTorch, Hugging Face Trainer, DeepSpeed, Megatron-LM, vLLM/Transformers). Each snippet is annotated with why it works so you can adapt the pattern to your own framework without losing fidelity.

DeepSpeed SIGBUS Exit Code -7 After Checkpoint Load

Q: How does this scale from 1 GPU to 1000 GPUs?

At single-GPU scale the symptom usually looks like slow convergence or a single anomalous loss value. At 64+ GPU scale, distributed interactions amplify a memory-mapped checkpoint file was truncated or deleted while the process still had it mapped, causing sigbus when the process tries to read the missing pages through collectives, and the failure can manifest as a full job abort. Always reproduce the fix at the smallest cluster configuration that still exhibits the symptom before promoting to production scale.

DeepSpeed training crashes with SIGBUS (exit code -7) after loading a checkpoint, with no Python traceback. This typically indicates a memory-mapped file access failure. The checkpoint file was truncated, deleted, or on a filesystem that was unmounted. Denpex detects the SIGBUS pattern and correlates it with checkpoint file integrity.

Quick answer

DeepSpeed training crashes with SIGBUS (exit code -7) after loading a checkpoint, with no Python traceback.

Symptom: dmesg shows SIGBUS or Bus error on the training process
Root cause: A memory-mapped checkpoint file was truncated or deleted while the process still had it mapped, causing SIGBUS when the process tries to read the missing pages. NFS mount became stale or was unmounted between checkpoint save and load, making the mapped file inaccessible. DeepSpeed's NVMe offload uses mmap for checkpoint buffers, and the underlying file was deleted or moved.
Recommended fix: Check if the checkpoint file still exists and has the correct size: ls -la <checkpoint_path>
How Denpex helps: Denpex investigates DeepSpeed SIGBUS Exit Code -7 After Checkpoint Load using the evidence you provide or your connected workload collects. Earlier rank, host or application evidence is needed to distinguish an initiating failure from a downstream report.

Data Integrity#deepspeed#sigbus#exit-code-7#checkpoint#nfs#mmap

What this failure is

DeepSpeed SIGBUS Exit Code -7 After Checkpoint Load is a Data Integrity failure seen during ML training runs. DeepSpeed training crashes with SIGBUS (exit code -7) after loading a checkpoint, with no Python traceback. This typically indicates a memory-mapped file access failure. The checkpoint file was truncated, deleted, or on a filesystem that was unmounted. Denpex detects the SIGBUS pattern and correlates it with checkpoint file integrity. Common tags: Deepspeed, Sigbus, Exit Code 7, Checkpoint.

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Why it happens (the mechanism)

A memory-mapped checkpoint file was truncated or deleted while the process still had it mapped, causing SIGBUS when the process tries to read the missing pages. NFS mount became stale or was unmounted between checkpoint save and load, making the mapped file inaccessible. DeepSpeed's NVMe offload uses mmap for checkpoint buffers, and the underlying file was deleted or moved. Disk corruption or filesystem journaling errors made the checkpoint file partially inaccessible. Taken together, these mechanisms explain why the failure is reproducible, why it tends to surface on specific workloads or scales, and why generic mitigation attempts often fall short without addressing the underlying cause.

What you'll observe

Training crashes with exit code -7 (SIGBUS) immediately after loading a checkpoint
No Python traceback is produced. The process dies at the OS level
All ranks crash simultaneously, suggesting a shared checkpoint file issue

Common symptoms and what they mean

Symptom	Why it happens
Process exits with code -7 (SIGBUS) or signal 7	A memory-mapped checkpoint file was truncated or deleted while the process still had it mapped, causing SIGBUS when the process tries to read the missing pages
No Python traceback or error message. Just an abrupt exit	NFS mount became stale or was unmounted between checkpoint save and load, making the mapped file inaccessible
dmesg shows SIGBUS or Bus error on the training process	DeepSpeed's NVMe offload uses mmap for checkpoint buffers, and the underlying file was deleted or moved
The crash occurs immediately after torch.load() or DeepSpeed checkpoint load	Disk corruption or filesystem journaling errors made the checkpoint file partially inaccessible
NFS mount points show as stale or unmounted in df output	A memory-mapped checkpoint file was truncated or deleted while the process still had it mapped, causing SIGBUS when the process tries to read the missing pages

Which systems are affected

Training with memory-mapped checkpoint files on NFS
DeepSpeed with NVMe offload checkpointing
Shared filesystem environments (NFS, Lustre, Ceph)
Long-running training jobs with periodic checkpoint loads

How to confirm this is the problem

Use this checklist to test the hypothesis against a small reproduction. No single line proves the root cause, so preserve the preceding events and compare one variable at a time.

✓Reproduce the failure from a clean checkpoint/seed: the symptom must appear without warm-up state from a previous run.
✓Verified signal present: Process exits with code -7 (SIGBUS) or signal 7
✓Verified signal present: No Python traceback or error message. Just an abrupt exit
✓Verified signal present: dmesg shows SIGBUS or Bus error on the training process
✓Verified signal present: The crash occurs immediately after torch.load() or DeepSpeed checkpoint load
✓Verified signal present: NFS mount points show as stale or unmounted in df output
✓A targeted fix from the "How to fix it" section eliminates or substantially reduces the symptom within one validation pass.

Root cause

A memory-mapped checkpoint file was truncated or deleted while the process still had it mapped, causing SIGBUS when the process tries to read the missing pages
NFS mount became stale or was unmounted between checkpoint save and load, making the mapped file inaccessible
DeepSpeed's NVMe offload uses mmap for checkpoint buffers, and the underlying file was deleted or moved
Disk corruption or filesystem journaling errors made the checkpoint file partially inaccessible

The fix and how to prevent it

Searchable error signature

search key

dmesg shows SIGBUS or Bus error on the training process
The crash occurs immediately after torch.load() or DeepSpeed checkpoint load

Use this text as a lookup key in logs and upstream issue trackers. It is not presented as a captured customer log. Confirm the cause from your own preceding events, versions, configuration and the cited references.

The fix and the prevention pattern

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Diagnose this failure in VS Code

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DeepSpeed errors in context

DeepSpeed changes when parameters, gradients and optimizer state are created, partitioned, gathered and offloaded. The hub separates ZeRO, memory, checkpoint and pipeline failures by lifecycle phase.

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