Heat a large skillet over medium-high heat. Cook and stir sausage in the hot skillet until browned and crumbly, 5 to 7 minutes. Drain and discard grease.
Meanwhile, preheat a smoker, according to manufacturer’s instructions, until temperature is a steady 220 degrees F (104 degrees F).
Remove silver skin and fat from pork loin, then slice into the center and “unroll” it until flat. Season both sides with pork rub. Spread one side with cream cheese, then layer jalapenos and cooked sausage evenly over top. Carefully roll loin up into a fairly tight log and secure with cooking twine.
Smoke in the preheated smoker until an instant-read thermometer inserted into the center reads 140 to 145 degrees F (60 to 63 degrees C), about 2 hours. Remove loin and wrap tightly in aluminum foil. Let rest for at least 20 minutes before serving.