Fix cudaErrorHostMemoryAlreadyRegistered: Duplicate Registration

Overview

cudaErrorHostMemoryAlreadyRegistered occurs when calling cudaHostRegister on already-registered memory.

Error Messages

CUDA error: host memory already registered
cudaErrorHostMemoryAlreadyRegistered

Common Causes

• •Registering same memory twice
• •Not tracking registered regions
• •Overlapping registrations

Solutions

static std::set<void*> registered;
if (registered.find(ptr) == registered.end()) {
    cudaHostRegister(ptr, size, 0);
    registered.insert(ptr);
}

Prevention Tips

• ✓Track registered memory
• ✓Register once at initialization

Code Examples

Before (Problematic)

Double registration.

cudaHostRegister(ptr, size, 0);
cudaHostRegister(ptr, size, 0);  // Error!

After (Fixed)

Track state.

if (!isRegistered(ptr)) {
    cudaHostRegister(ptr, size, 0);
    markRegistered(ptr);
}

Frequently Asked Questions

Related Errors

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