The problem of pm-hibernate solved

Abstract: Solve the problem of pm-hibernate restarts computer.

When I try to hibernate my laptop running Arch Linux with pm-hibernate which is also used by GNOME behind the scene, it restarts immediately after hibernate to disk. I checked Arch wiki and find a link to opensuse wiki Pm-Utils. After add a s2ram force option as instructed, the problem is solved. I added the following lins to /etc/pm/config.d/config

HIBERNATE_MODE="shutdown"
S2RAM_OPTS="-f -p -m"

The "-p" parameter was the key to a successful hibernate for me.