Non-dimmable LED on dimmer. Fire hazard?
LED lights are made up of two parts the LED itself and a driver which transforms the house power to the operating power of the LED. The smoke is more than likely coming from the driver of the LED if it is non dimmable. The obvious is it was not designed for dimming and that would cause it to burn up. So if you have LED's that are non dimmable then you need to take them off of the dimmers or replace the LED's with dimmable drivers.

Stay safe and good luck