On Mon, Jul 2, 2018 at 7:01 PM Mathieu Desnoyers <mathieu.desnoy...@efficios.com> wrote: > > One thing to consider is how we will implement the load of that pointer > on the kernel side.
Use "get_user()". It works for 64-bit objects too, and it will be atomic in the 32-bit sub-parts on a 32-bit architecture. Again: there is no point in trying to be atomic in the full 64 bits (when you're running on 32-bit). The upper bits don't have to "match" the lower bits. They just have to be zero. So doing it as two loads is fine - the same way it's perfectly fine to do it as two stores (since the store to the upper bits will always be zero). Linus