cuda runtime ai_generated true

RuntimeError: CUDA error: an illegal memory access was encountered

ID: cuda/illegal-memory-access

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85%Fix Rate
88%Confidence
50Evidence
2023-01-01First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
12 active — — —
12 active — — —

Root Cause

GPU kernel accessed invalid memory — buffer overrun, freed memory, or wrong tensor shape.

generic

Workarounds

  1. 93% success Set CUDA_LAUNCH_BLOCKING=1 to get accurate error location 
    # Run with compute-sanitizer for precise memory error location:
compute-sanitizer --tool memcheck python train.py
# Or for C/C++ CUDA code:
compute-sanitizer ./my_cuda_app
# Shows exact line, thread, and address of the illegal access

    Sources: https://docs.nvidia.com/cuda/cuda-c-programming-guide/index.html#error-handling

  2. 88% success Check tensor shapes and indices — off-by-one errors are the most common cause 
    Verify all indexing operations stay within tensor dimensions

Dead Ends

Common approaches that don't work:

  1. Catching the error and continuing training 90% fail

    GPU is in error state; all subsequent CUDA operations will fail

  2. Increasing GPU memory allocation 80% fail

    Illegal access is about address validity, not memory quantity

Error Chain

Frequently confused with: