One problem related to brake disc pads has been reported for the 2009 Mazda CX9. The most recently reported issues are listed below.
I was taking my daughter to high school in the morning with my son in the car as well. In the parking lot of the high school, I applied the brakes but the brakes did not work. My foot was all the way to the floor when they finally caught but I was out in the line of traffic and luckily no one hit me and injured my son or myself. After replacing the rotors and brake pads that did not fix the situation, I have since learned that the brake booster has been an ongoing issue with Mazda cx-9 that was even investigated by the NHTSA without having a recall. How does something so critical in the safety of lives does not generate a recall that the NHTSA has seen repeated complaints of the same issue without advising or caring about the safety of the consumers and other drivers. It is an ongoing issue that Mazda has not addressed or corrected.