gdrcopy gdr_pin_buffer failed GPU virtual address is not mapped to BAR1 aperture
GDRCopy could not pin the GPU virtual address into the CPU-visible BAR1 aperture. The allocation is not eligible for peer-direct mapping, BAR1 space is exhausted, or the kernel module and driver disagree. This entry explains how to confirm the cause, apply the fix, and separate it from adjacent gdr-fabric failures.
gdrcopy gdr_pin_buffer failed GPU virtual address is not mapped to BAR1 aperture means GDRCopy could not pin the GPU virtual address into the CPU-visible BAR1 aperture. The allocation is not eligible for peer-direct mapping, BAR1 space is exhausted, or the kernel module and driver disagree. Preserve the first preceding error, then run the targeted control below.
What this failure is
The literal signature is "gdrcopy gdr_pin_buffer failed GPU virtual address is not mapped to BAR1 aperture". It is a communication failure associated with GPUDirect RDMA, RoCE, GDRCopy, and NUMA topology. The line identifies the failing operation or subsystem, while the surrounding evidence decides whether it is the initiating fault or a downstream symptom.
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Why it happens (the mechanism)
GDRCopy could not pin the GPU virtual address into the CPU-visible BAR1 aperture. The allocation is not eligible for peer-direct mapping, BAR1 space is exhausted, or the kernel module and driver disagree. 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.
What you'll observe
- The workload stops or loses forward progress after emitting "gdrcopy gdr_pin_buffer failed GPU virtual address is not mapped to BAR1 aperture".
- 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.
Common symptoms and what they mean
| Symptom | Why it happens |
|---|---|
| gdrcopy gdr_pin_buffer failed GPU virtual address is not mapped to BAR1 aperture | GDRCopy could not pin the GPU virtual address into the CPU-visible BAR1 aperture. The allocation is not eligible for peer-direct mapping, BAR1 space is exhausted, or the kernel module and driver disagree. |
| The same operation fails at a consistent stage of GPUDirect RDMA, RoCE, GDRCopy, and NUMA topology. | The decisive evidence is the first log line that precedes "gdrcopy gdr_pin_buffer failed GPU virtual address is not mapped to BAR1 aperture" and differs from a healthy run. |
| The first related warning appears before the final exception and names the causal subsystem. | A nearby failure remains a competing hypothesis until a control separates configuration, capacity, transport, and hardware causes. |
| A known-good control changes one variable and either reproduces or clears the failure. | GDRCopy could not pin the GPU virtual address into the CPU-visible BAR1 aperture. The allocation is not eligible for peer-direct mapping, BAR1 space is exhausted, or the kernel module and driver disagree. |
Which systems are affected
- GPUDirect RDMA, RoCE, GDRCopy, and NUMA topology
- production-shaped multi-accelerator workloads
- containerized and bare-metal deployments of the same stack
How to confirm this is the problem
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 "gdrcopy gdr_pin_buffer failed GPU virtual address is not mapped to BAR1 aperture" and preserve at least 100 lines before it.
- ✓Identify which rank, node, device, or process emitted the first related warning.
- ✓inspect nvidia-smi -q BAR1 usage and confirm the pointer came from a supported CUDA device allocation on the same GPU. Free stale mappings and retry from a clean process.
- ✓Repeat the same input after the targeted change and require the signature to disappear.
- ✓Resume from job start after BAR1 mapping passes the control test only after the control passes.
Example training logs (fingerprint)
gdrcopy gdr_pin_buffer failed GPU virtual address is not mapped to BAR1 apertureTimestamps 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.
The fix and the prevention pattern
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Why the recommended fix works
confirm the gdrdrv module is loaded and run the GDRCopy copybw test on the same GPU before retrying the application. This changes the condition in the causal diagnosis instead of hiding the outer exception. The repeated control proves ownership before recovery from job start after BAR1 mapping passes the control test.
Code examples
# Preserve evidence before restarting
NCCL_DEBUG=INFO NCCL_DEBUG_SUBSYS=INIT,NET,COLL torchrun train.py
ibstat
ethtool -S <interface>
# Find the exact signature in the complete log
rg -n -F -- "gdrcopy gdr_pin_buffer failed GPU virtual address is not mapped to BAR1 aperture" <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.
Best practices by model family
| Model / Stack | Recommendation | Notes |
|---|---|---|
| First response | Preserve the first failure | Keep the context before "gdrcopy gdr_pin_buffer failed GPU virtual address is not mapped to BAR1 aperture" so aggregation does not erase causality. |
| Confirmation | Change one variable | Use a known-good node, rank, input, or configuration as the control. |
| Recovery | Resume from job start after BAR1 mapping passes the control test | Resume only after the literal signature no longer appears in the same control. |
With the fix vs without the fix
| Dimension | With the fix | Without the fix |
|---|---|---|
| Evidence | First preceding error and one controlled comparison | Only the final aggregated exception |
| Fix | confirm the gdrdrv module is loaded and run the GDRCopy copybw test on the same GPU before retrying the application. | Retrying the unchanged workload |
| Exit criterion | "gdrcopy gdr_pin_buffer failed GPU virtual address is not mapped to BAR1 aperture" is absent in the repeated control | The job happened to run once |
Real engineering notes
“Treat "gdrcopy gdr_pin_buffer failed GPU virtual address is not mapped to BAR1 aperture" as a search key and an investigation checkpoint, not as proof of every cause associated with the phrase. The high-value evidence is what changed immediately before it and whether the failure follows the workload, node, or configuration.”
Visual fingerprint
literal error captured
|
v
find first preceding failure
|
v
run one known-good control
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+-- follows workload --> inspect input or configuration
+-- follows node ------> inspect hardware or platform
+-- disappears --------> validate the targeted fixDiagnose this failure in VS Code
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Root cause
- GDRCopy could not pin the GPU virtual address into the CPU-visible BAR1 aperture. The allocation is not eligible for peer-direct mapping, BAR1 space is exhausted, or the kernel module and driver disagree.
- The decisive evidence is the first log line that precedes "gdrcopy gdr_pin_buffer failed GPU virtual address is not mapped to BAR1 aperture" and differs from a healthy run.
- A nearby failure remains a competing hypothesis until a control separates configuration, capacity, transport, and hardware causes.
The fix and how to prevent it
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Frequently asked questions
Twelve targeted questions that engineers and on-call staff most commonly ask about this failure.
What does "gdrcopy gdr_pin_buffer failed GPU virtual address is not mapped to BAR1 aperture" mean?
Is this line always the root cause?
What should I collect before restarting?
What is the fastest confirmation?
How do I prevent it from recurring?
Don't just read the fix, diagnose your run
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