X freezing occasionally

[walt]

Hi list,

This freezing problem happened once yesterday for the first time, and
(so far) only once today, so it's not easy to reproduce.

I'm running an oddball gemisch of stable and unstable software, so it's
definitely not a "supported configuration".

I'm not at all surprised this is happening, but I thought I'd ask for your
observations anyway.

Both times X has locked up, firefox was just starting to load a web page
that I'd clicked on.  (Two different websites.)

I can ssh into the machine and use top to see /usr/bin/Xorg using 100%
of CPU (an older single-core amd 32-bit cpu).

Strace shows Xorg is printing endless numbers of the messages below:
ioctl(7, 0x40086482, 0xbffdc7c8)        = ? ERESTARTSYS (To be restarted)
--- SIGALRM (Alarm clock) @ 0 (0) ---
sigreturn()                             = ? (mask now [])

If I'm interpreting correctly, fd 7 is (no surprise):
X  3758   root   7u   CHR   226,0   0t0    2008 /dev/dri/card0

Now for dessert :)

(II) NOUVEAU(0): Modeline "1280x1024"x76.0  141.82  1280 1376 1512 1744  1024 1025 1028 1070 -hsync +vsync (81.3 kHz)
[mi] EQ overflowing. The server is probably stuck in an infinite loop. [Yes, I suspected that already.]

Backtrace:
0: /usr/bin/X (xorg_backtrace+0x3b) [0x80a169b]
1: /usr/bin/X (mieqEnqueue+0x196) [0x80a14e6]
2: /usr/bin/X (xf86PostMotionEventP+0xe8) [0x80b4958]
3: /usr/lib/xorg/modules/input/evdev_drv.so (0xb69da000+0x3321) [0xb69dd321]
4: /usr/lib/xorg/modules/input/evdev_drv.so (0xb69da000+0x35c9) [0xb69dd5c9]
5: /usr/bin/X (0x8048000+0x663bf) [0x80ae3bf]
6: /usr/bin/X (0x8048000+0xea23c) [0x813223c]
7: (vdso) (__kernel_sigreturn+0x0) [0xb76f5400]
8: /usr/lib/libdrm.so.2 (drmCommandWrite+0x3b) [0xb715986b]
9: /usr/lib/libdrm_nouveau.so.1 (0xb7176000+0x2e12) [0xb7178e12]
10: /usr/lib/libdrm_nouveau.so.1 (nouveau_bo_map_range+0xf1) [0xb7179001]
11: /usr/lib/libdrm_nouveau.so.1 (nouveau_bo_map+0x33) [0xb71790d3]
12: /usr/lib/xorg/modules/drivers/nouveau_drv.so (0xb712c000+0x4eca) [0xb7130eca]
13: /usr/lib/xorg/modules/libexa.so (0xb70fa000+0x7602) [0xb7101602]
14: /usr/bin/X (0x8048000+0xaa26d) [0x80f226d]
15: /usr/bin/X (0x8048000+0x43d6e) [0x808bd6e]
16: /usr/bin/X (0x8048000+0x464ff) [0x808e4ff]
17: /usr/bin/X (0x8048000+0x1ddf5) [0x8065df5]
18: /lib/libc.so.6 (__libc_start_main+0xe6) [0xb721bbb6]
19: /usr/bin/X (0x8048000+0x1d9a1) [0x80659a1]

Kernel is today's Linus.git with its (unmodified) nouveau support.
x11-drivers/xf86-video-nouveau-0.0.16_pre20100615 (gentoo linux)
x11-drivers/xf86-input-evdev-2.4.0
x11-libs/libdrm-2.4.21
x11-base/xorg-server-1.7.7-r1

My real question is: how likely is this freezing to be caused by an actual bug
somewhere, or is it more likely that my odd mix of package versions just don't
play nicely together.

BTW, I'm just doing all of this learn something, not to build a production machine.
I can afford to tinker with it a bit :)

Thanks.