Those spiraling trails of vapor are called "wing tip vortices". They are caused by the compression of air rolling off the wingtips. What you see is water vapor just prior to condensing into water.

Water vapor, from the moisture in the air, as the air pressure changes during landings.

I would have said that it's condensation coming off the wings after a descent from a higher, colder altitute. I will, however, defer to those with a more intimate knowledge of airline operating procedure.

Thats not smoke, thats jet fuel being dumped before landing.

It lowers the possibility of a fire, should the plane crash upon touching down.