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This is doable, but the only way I know of is imperfect.
bool is_cuda_associated(void const* ptr) { CUmemorytype mem_type; CUresult status = cuPointerGetAttribute( &mem_type, CU_POINTER_ATTRIBUTE_MEMORY_TYPE, reinterpret_cast<CUdeviceptr>(ptr)); switch(status) { case CUDA_SUCCESS: return true; case CUDA_INVALID_VALUE: return false; default: handle_error_somehow(); // e.g. throw an exception } }for CUDA-associated memory, we get their type (host, device, etc.) and the API call is successful; and it fails, i.e. returns an error status, for non-CUDA pointers. But therein lies the problem with this approach - the intentional triggering an error. This shows up as error if you run your app, for example, via compute-sanitizer --tool memcheck.
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Dereferencing some random pointer is a great way to crash your process. Nevermind the mere fact of losing track of what some pointer refers to is a massive code stench in the first place.
2026-01-16T16:12:59.323Z+00:00
@AndrewHenle: 1. No pointer is dereferenced here. The cast is due to the API call taking the address as a number. 2. Nobody is "losing track". This is useful in code that needs to act differently on memory areas depending on their type; especially in the context of libraries. It is also of use when debugging.
2026-01-16T16:27:09.393Z+00:00
"No pointer is dereferenced" - do you know that for sure? Perhaps cuPointerGetAttribute() has to internally dereference the pointer to determine the characteristics of the memory block that the pointer is pointing at. It's an implementation detail.
2026-01-16T16:59:22.837Z+00:00
@RemyLebeau Because the function specs say "If ptr was not allocated by, mapped by, or registered with a CUcontext which uses unified virtual addressing then CUDA_ERROR_INVALID_VALUE is returned." - they are specified on all pointers, not just cuda ones. The function specs could lie, but that is an interface lie, not an implementation detail.
2026-01-16T17:59:52.503Z+00:00
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