Suspending to RAM on Debian laptop

I am tracking Debian sid on my Thinkpad laptop, a few months ago it started to use pm-utils and broke suspending to RAM (sleep) functionality. Basically, the machine would go to sleep then immediately resume.
It turned out that this problem can be easily fixed by creating a file /etc/pm/config.d/local, and put in a line

SUSPEND_MODULES="e1000"

The reason is that pm-utils by default does not unload Ethernet card module e1000, so the machine would be waken up by Ethernet card activities.