The likely problem is the stream argument cannot be 0 (i.e. default stream). You will need to specify a named stream that was created with cudaStreamCreate*()

You also don't have to specify the location hints because "The cudaMemcpyAttributes::srcLocHint and cudaMemcpyAttributes::dstLocHint allows applications to specify hint locations for operands of a copy when the operand doesn't have a fixed location. That is, these hints are only applicable for managed memory pointers on devices where cudaDevAttrConcurrentManagedAccess is true or system-allocated pageable memory on devices where cudaDevAttrPageableMemoryAccess is true."