I kept having random freezes on my desktop running CentOS 6.7. I run a win7 guest, as well as Firefox on the host. On many occasions, the system would just hang for over 10 seconds at a time, with the only symptom that the CPU usage would spike for the duration. When it was happening regularly, I fired up top and saw that khugepaged was hitting 100%.
I found this page detailing how to disable khugepaged, and after going through the steps and rebooting the host, I have not seen the problem resurface yet!