No FallDamage Taking

One day I was crazy and thought about doing some dying things. I made a platform in Creative from up to down, and I tried in survival and jumped along it to see if I would die. The platform was high and plus the height I could jump, it took about 2.5 hearts of fall damage. But then, once, twice, three times, I was NOT taking any damage. Then I found, while I was jumping all the way down, there will be a possibility not taking ANY fall damage. This is a huge problem.