Lawnmower leaking oil?

if you tilted the mower over to look under it.it could have caused oil to go up in the piston or if it's overfull of oil it will go up in the piston and smoke.this would be white smoke if the smoke if dark you have a fuel or air filter problem.make sure the air filter is cleaned or new.if it's a foam filter you can wash it with soap and water let it dry good before you put it back in.hope this helps.