I appear to have a rather big mem leak somewhere in kernel space. Every time I start & close X, 40-120mb of ram disappears into some limbo, so that it is shown as used but no process in ps/top claims it.

Since X causes it and symptoms point to kernel space, I guess this is DRM's fault. Anybody seen anything like this?
Hints on where to continue?

I'd file a bug report, but I'm really short on time now, no time to test git versions of anything. Also, there's nothing special in the logs, beside a message that the graphics card MTRR is not used (?).

Linux 2.6.30.5 x64, Radeon drm that comes with (1.30 I guess)
Xorg 1.6.1, xf86-radeon 6.11, Mesa 7.2 (user space is 32-bit)

Macbook Pro, Mobility Radeon X1600 128mb gddr3

dmesg: http://pastebin.ca/1555845
Xorg.0.log: http://pastebin.ca/1555847

/proc/mtrr:
reg00: base=0x0ffe00000 ( 4094MB), size= 2MB, count=1: write-protect
reg01: base=0x000000000 ( 0MB), size= 2048MB, count=1: write-back
reg02: base=0x07ff00000 ( 2047MB), size= 1MB, count=1: uncachable
reg03: base=0x080000000 ( 2048MB), size= 128MB, count=1: write-combining
RAM numbers and how I measured:
#!/bin/sh
sync
sudo sh -c "echo 3 > /proc/sys/vm/drop_caches"
free

total used free shared buffers
Mem: 2042252 153024 1889228 0 32
Swap: 0 0 0
Total: 2042252 153024 1889228

total used free shared buffers
Mem: 2042252 219576 1822676 0 32
Swap: 0 0 0
Total: 2042252 219576 1822676

total used free shared buffers
Mem: 2042252 285744 1756508 0 32
Swap: 0 0 0
Total: 2042252 285744 1756508