Você pode executar o Docker 1.7 em um kernel 2.6.32-431 ou superior, mas precisa de pelo menos o RHEL 6.6. De acordo com a documentação :
Docker requires a 64-bit installation regardless of your Red Hat version. Docker requires that your kernel must be 3.10 at minimum. Red Hat 7 runs the 3.10 kernel, 6.6 does not. We make an exception for Red Hat 6.6. To run Docker on Red Hat-6.6 or later, you need kernel 2.6.32-431 or higher.