Is it ok for Passover?
It depends on you are whether you are Ashkenazic or Sephardic. I believe Sphardic Jews may be allowed to eat oatmeal during Passover, but you should check on that.
Although oats is one of the five grains observant Ashkenazic Jews are allowed to eat during passover, there are additional prohibitions against eating these grains in any form other than matzo during Passover.
Because of how the oats are treated for making oatmeal, it is not allowed during Passover. Oats are heat-treated to prevent them from becoming rancid, if this heating is done with “wet” steam, the oats/oatmeal are considered to be "Chametz" (any food product made of wheat, barley, rye, oats or spelt, or their derivatives, which is leavened or fermented), and would not be allowed during Passover.
Unless a food's package is marked "Kosher for Passover" or "kasher l'pesach" , it should be avoided during the holiday.
Here are two recipes for a "mock oatmeal" that is Kosher for Passover:
I hope I've been a help.