For the avoidance of doubt, @habi is absulutely correct here.  We cannot copy data from Wikipedia, because Wikipedia's licence is not compatible with ours.  It doesn't matter that it is just "an elevation and a population"; it will need to be redacted from OSM.
- Andy,
from OSM's Data Working Group
PS:  Whatever was used as a source _by wikipedia_ may of course be compatible with OSM.  I'd be surprised if something did not exist with that data under a compatible licence, but it's down to you to veryify that, not just copy from wikipedia.
