Bumps that appear on the surface of a floor covering material are usually the result of nails or screws beneath the material that have loosened and raised. If there are bumps showing through the flooring from your subfloor, place a block of wood over the bumps and tap lightly with a hammer.

If this doesn't work, the bumps will be difficult to get rid of and you'll have to remove the floor covering to gain access to the subfloor so you can replace the nails or screws.