Resistors are generally very linear. They're put in the same category as transformers, capacitors, and inductors, where we just ignore the non-linearities--they're usually too small to measure, although reverse-biased electrolytic capacitors are definitely nonlinear and I've heard you can be affected by nonlinearity on carbon-composition resistors if you put enough voltage across them--like, 100V--don't know if it's true, just "heard it somewhere".
Diodes are incredibly nonlinear, that's the whole point of having diodes.
Diodes are incredibly nonlinear, that's the whole point of having diodes.