upgrade 3.3 -> 5.2.1, server now hangs

[Alexei Khalimov]

Hello!

Recently I have upgraded our server from 3.3 to 5.2.1
Now it hangs every 2-3 days without any warnings in
syslog or system console.
System DMESG can be found at:
  http://www.divo.ru/~lesha/dmesg.txt
What can be the problem? Any ideas?

Cheers,
       Alex