Actually, it is sufficient to call CuArray() twice. From the second call on CuArray() works:
julia> using CuArrays
julia> B = ones(10_000) ./ 2;
julia> A = ones(10_000) .* π;
julia> cuB = CuArray(B);
ERROR: CUDA error: invalid device ordinal (code #101, ERROR_INVALID_DEVICE)
Stacktrace:
[1] macro expansion at /users/omlins/.julia/packages/CUDAdrv/LC5XS/src/base.jl:147 [inlined]
[2] CUDAdrv.CuContext(::CUDAdrv.CuDevice, ::CUDAdrv.CUctx_flags) at /users/omlins/.julia/packages/CUDAdrv/LC5XS/src/context.jl:112
[3] Type at /users/omlins/.julia/packages/CUDAdrv/LC5XS/src/context.jl:111 [inlined]
[4] device!(::CUDAdrv.CuDevice) at /users/omlins/.julia/packages/CUDAnative/AGfq2/src/init.jl:68
[5] initialize at /users/omlins/.julia/packages/CUDAnative/AGfq2/src/init.jl:39 [inlined] (repeats 2 times)
[6] macro expansion at ./logging.jl:305 [inlined]
[7] maybe_initialize(::Symbol) at /users/omlins/.julia/packages/CUDAnative/AGfq2/src/init.jl:31
[8] macro expansion at /users/omlins/.julia/packages/CUDAdrv/LC5XS/src/base.jl:140 [inlined]
[9] #alloc#3(::CUDAdrv.Mem.CUmem_attach, ::Function, ::Int64, ::Bool) at /users/omlins/.julia/packages/CUDAdrv/LC5XS/src/memory.jl:161
[10] alloc at /users/omlins/.julia/packages/CUDAdrv/LC5XS/src/memory.jl:157 [inlined] (repeats 2 times)
[11] macro expansion at /users/omlins/.julia/packages/CuArrays/f4Eke/src/memory.jl:237 [inlined]
[12] macro expansion at ./util.jl:213 [inlined]
[13] (::getfield(CuArrays, Symbol("##17#18")){Base.RefValue{CUDAdrv.Mem.Buffer}})() at /users/omlins/.julia/packages/CuArrays/f4Eke/src/memory.jl:236
[14] lock(::getfield(CuArrays, Symbol("##17#18")){Base.RefValue{CUDAdrv.Mem.Buffer}}, ::ReentrantLock) at ./lock.jl:101
[15] macro expansion at ./util.jl:213 [inlined]
[16] alloc(::Int64) at /users/omlins/.julia/packages/CuArrays/f4Eke/src/memory.jl:221
[17] CuArray{Float64,1}(::Tuple{Int64}) at /users/omlins/.julia/packages/CuArrays/f4Eke/src/array.jl:45
[18] convert at /users/omlins/.julia/packages/CuArrays/f4Eke/src/array.jl:99 [inlined]
[19] convert at /users/omlins/.julia/packages/CuArrays/f4Eke/src/array.jl:105 [inlined]
[20] CuArray(::Array{Float64,1}) at /users/omlins/.julia/packages/GPUArrays/hzyWn/src/construction.jl:36
[21] top-level scope at none:0
julia> cuB = CuArray(B);
julia> cuA = CuArray(A);
julia> cuC = 2 .* cuA ./ cuB;
julia>
julia> all(cuC .≈ 4*π);
julia> all(cuC .≈ 4*π)
true
julia> typeof(cuC)
CuArray{Float64,1}
julia>
It looks like somehow some (lazy) initialization is triggered too late.