The vulnerabilities of OS kernel are usually exploited by attackers to execute arbitrary code with kernel privilege (i.e., return-to-user attacks, ret2user) and to steal other processes' private data. In this paper, a transparent OS kernel memory access mediator based on VMM (virtual machine monitor) is proposed, and a non-bypassable low performance overhead memory page tracker is provided to get the memory usage information in real-time. Combined with a safe loader, the new method guarantees the code integrity of dynamic shared objects during run-time. It also ensure that, even when the OS kernel is compromised, the application's memory private data is still safe. A prototype is implemented on the Linux OS, and the evaluation experiments show that it only incurs about 6%~10% performance overhead for most SPEC benchmark tests.