I'm interested in laying laminate flooring over the top of existing intact linoleum. First, any problems with that? Secondly, there are unfortunately also uneven spots under the linoleum that causes ridges which are discernable even as you walk across it. I have gone as far as taking a level and running along the spots to see if I was just out of my mind.. nope. Are these ridges something that I need to address or can I lay laminate over the top of them? How can I go about leveling them if needed? Self-leveling compound/concrete?
The answer to this is "look at the instructions for the laminate", and see what they say. If you have old-school hard laminate (like you find in schools/government buildings/grocery stores), then it's a nice hard surface and it is fine. If it is resilient flooring (kitchen vinyl), then the answer is read the instructions.
If you have big ridges, I'd probably just grind them down with an angle grinder.