All kernels (even Dev) are SMP on 2.0.
There is no longer any benefit to loading a uniprocessor kernel (Mentioned a little here but also in more detail by me around the forum).
I've had some issues with the dev kernel in certain setups as well but it does a lot more strict locking checking and reporting, which is what you appear to have hit here.
We have enough debug info in the stock kernel these days that the full dev kernel isn't quite as necessary on its own, but still useful in rare cases.