Hi. I've upgraded to kernel26beyond 2.6.20.beyond2-1 some time ago now, and I can't suspend to disk. It worked well with the 2.6.19 beyond kernels etc, but it stopped after the upgrade. I haven't reported before, since I had no time to check what was wrong. Now, I'm using xfs as my root partition and this seems to be the root of my problem as the log from from my hibernation attempts shows:
Preparing Image. Try 1.
Free:10092(10011). Sets:28872(26011),223130(193409). Header:10. Nosave:2-0=2. Storage:0/252502(464966). Needed:(100+2357)2458-10011-0)-7553|(252502-
464966)-212464|0.
Stopping tasks ...
Stopping kernel threads timed out after 20 seconds (1 tasks refusing to freeze):
xfssyncd
Restarting tasks ... <4> Strange, xfssyncd not stopped
done.
Suspend2 debugging info:
- Suspend core : 2.2.9.7
- Kernel Version : 2.6.20-beyond
- Compiler vers. : 4.1
- Attempt number : 1
- Parameters : 17 81920 0 1 0 4
- Overall expected compression percentage: 0.
- Compressor is 'lzf'.
- SwapAllocator active.
Swap available for image: 465875 pages.
- FileAllocator inactive.
- No I/O speed stats available.
- Extra pages : 0 used/500.

I've been googling around for an answer, but haven't found a working solution. This list seems to be discussing a similar issue:
http://www.archivesat.com/Suspend2_-_hibernation_for_Linux/thread2973017.htm