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SIGBUS (Signal 7): Meaning, Exit Code 135 & Fix

SIGBUS is Unix signal 7. A process terminated by it reports exit code 135 (128 + 7).

SIGBUS signals a hardware-level invalid memory access (misalignment, truncated mmap). When it kills a process, the shell reports exit code 135 - the 128 + signal-number convention.

What it means

Often an mmap of a file that was truncated, or misaligned access on strict architectures.

When it happens in CI

  • mmap of a file that shrank underneath the process.
  • Out-of-space on a tmpfs-backed mmap.
  • Misaligned access on ARM.

How to handle it

Check disk/tmpfs space and that mapped files are intact; on ARM, verify alignment assumptions.

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