Why is my truck smokin so much?

I have a 98 chevy suburban. last week it began to leak oil from the bottom so we had it checked and they said the gaskets needed to be replaced. this was done. when they did this, the leak stopped but they put way too much oil in the truck and so we took it back to let some of the oil out. since then, it has been smokin even while in idle. It gets worse while driving. it is smokin from the tail pipe. Someone said that it's just burning off that excess oil, it'll take some time. Does this sound like the problem? The smoke is very white and thick. I don't know if I included enough details, I don't know anything about cars/trucks. Please help if anyone knows what could be causing the excessive smoke. Thanks so much. :o)