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fix(cuda.core): surface CUresult when graph instantiation fails #2719

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fix(cuda.core): surface CUresult when graph instantiation fails #2719

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35e7b74
raise CUDAError instead of RuntimeError to fix a test case failure du…
lijinf2 Aug 27, 2026
6aa629f
add docstring saying HANDLE_RETURN adds CUresult message into CUDAErr…
lijinf2 Aug 27, 2026
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7 changes: 6 additions & 1 deletion cuda_core/cuda/core/graph/_graph_builder.pyx
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Original file line number Diff line number Diff line change
Expand Up @@ -176,6 +176,7 @@ class GraphCompleteOptions:
def _instantiate_graph(source, options: GraphCompleteOptions | None = None) -> Graph:
cdef GraphHandle h_graph
cdef GraphExecHandle h_exec
cdef cydriver.CUresult status

if isinstance(source, GraphBuilder):
GB_check_open(<GraphBuilder>source)
Expand Down Expand Up @@ -209,7 +210,11 @@ def _instantiate_graph(source, options: GraphCompleteOptions | None = None) -> G
# The exec is adopted only when result_out reports success, so the
# diagnostics below run before the handle is checked.
h_exec = create_graph_exec_handle(h_graph, &params)
status = get_last_error()
if params.result_out == driver.CUgraphInstantiateResult.CUDA_GRAPH_INSTANTIATE_ERROR:
# HANDLE_RETURN raises CUDAError with the CUresult name and message (e.g. CUDA_ERROR_INVALID_VALUE)
# when status is not CUDA_SUCCESS.
HANDLE_RETURN(status)
raise RuntimeError(
"Instantiation failed for an unexpected reason which is described in the return value of the function."

@rwgk rwgk Aug 28, 2026

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Suggested change
"Instantiation failed for an unexpected reason which is described in the return value of the function."
"CUDA graph instantiation failed, but cuGraphInstantiateWithParams "
"returned CUDA_SUCCESS; no driver error details are available."

It's an existing problem, but the error message is very unhelpful:

  • "Return value" means the CUresult from cuGraphInstantiateWithParams.
  • That value is not exposed to _instantiate_graph()s caller; it is local status.
  • The RuntimeError is reachable only when status == CUDA_SUCCESS, because otherwise HANDLE_RETURN(status) raises CUDAError.
  • "The function" is ambiguous among _instantiate_graph, create_graph_exec_handle, and cuGraphInstantiateWithParams.

It'd be great to replace it while we're at it.

)
Expand All @@ -230,7 +235,7 @@ def _instantiate_graph(source, options: GraphCompleteOptions | None = None) -> G
raise RuntimeError(f"Graph instantiation failed with unexpected error code: {params.result_out}")

if as_cu(h_exec) == NULL:
HANDLE_RETURN(get_last_error())
HANDLE_RETURN(status)
return Graph._init(h_exec)


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