No, If I replace the self.c_activation_f with nn.ReLU() module, It works well.
and if I save the model with torch.save() function, the size of the saved model is quite big comparing to same model built with separate modules like nn.ReLU(), nn.BatchNorm2d not pre-defined module saved to self variable.
It seems that it has something to do with module pre defined in init() function.
If I build a model with pre defined modules with self variable, I think the modules are added several times and forward/backward paths as well