Created attachment 17520 [details]
lspci -v command output

Created attachment 17522 [details]
dmesg output log

Hope, this log is useful

Corrected some information.

I'd like to just make a minor comment  - that maybe this issue is also related 
to my bug #16664 where I also see the deadlock in  I830WaitLpRing

I'm also usually running latest 2.6.26-rcX kernel.

#0  0x0000003181a32fa5 in raise (sig=<value optimized out>)
    at ../nptl/sysdeps/unix/sysv/linux/raise.c:64
#1  0x0000003181a34b13 in abort () at abort.c:88
#2  0x00000000004f186d in FatalError (
    f=0x56caa0 "Caught signal %d.  Server aborting\n") at log.c:554
#3  0x0000000000479de8 in xf86SigHandler (signo=11) at xf86Events.c:766
#4  <signal handler called>
#5  DRILock (pScreen=0x1981590, flags=0) at dri.c:2181
#6  0x000000000301ba77 in I830LeaveVT (scrnIndex=<value optimized out>, 
    flags=<value optimized out>) at i830_driver.c:3149
#7  0x00000000004611dd in AbortDDX () at xf86Init.c:1302
#8  0x00000000004f1188 in AbortServer () at log.c:406
#9  0x00000000004f1855 in FatalError (f=0x30478e4 "lockup\n") at log.c:552
#10 0x0000000003011e51 in I830WaitLpRing (pScrn=0x1979000, n=8, 
    timeout_millis=0) at i830_accel.c:150
#11 0x0000000003011fec in I830EmitFlush (pScrn=0x19e5070) at i830_accel.c:220
#12 0x0000000004094976 in DRIWakeupHandler (wakeupData=0x0, result=-1, 
    pReadmask=0x7d5e00) at dri.c:1608
#13 0x000000000044a38b in WakeupHandler (result=-1, pReadmask=0x7d5e00)
    at dixutils.c:417
#14 0x00000000004e40ff in WaitForSomething (pClientsReady=0x1be83c0)
    at WaitFor.c:239
#15 0x00000000004464ef in Dispatch () at dispatch.c:375
---Type <return> to continue, or q <return> to quit---
#16 0x000000000042cc4d in main (argc=8, argv=0x7fff4a842008, 
    envp=<value optimized out>) at main.c:441

Petr, do you have specific steps to reproduce this problem?  Does it go away if you disable DRI?  What about if you add Option "ExaNoComposite" "true" to your xorg.conf intel driver section?

(In reply to comment #5)
> Petr, do you have specific steps to reproduce this problem?  Does it go away if
> you disable DRI?  What about if you add Option "ExaNoComposite" "true" to your
> xorg.conf intel driver section?
> 

Well, I don't really know how to reproduce the bug. Generally it's caused by starting some application, but each time this app is different.

I'll try to disable DRI and use ExaNoComposite and let you know.
I'm using WM Fluxbox with no composite features (AFAIK).

Btw. I'm using still the version 2.3.2, but I can easily upgrade to 2.4.0. Which version is better for you me to debug?

Created attachment 17923 [details]
Xorg config file

This file is before trying to disable DRI and use ExaNoComposite.

It's generally easiest for us if you use the latest released version, or better yet, the git tree directly.

The ExaNoComposite option is somewhat confusingly named.  It actually disables hardware Xrender acceleration (Xrender being the extension used to draw most things on the screen these days) and doesn't have much to do with the Xcomposite extension.

Thanks for testing.

(In reply to comment #8)
> It's generally easiest for us if you use the latest released version, or better
> yet, the git tree directly.
> 

So I'm running now X.Org X Server 1.4.99.906 (1.5.0 RC 6), xserver-xorg-video-intel 2.4.0 with debug symbols.

And I disabled DRI and add Option "ExaNoComposite" "true".

I'll report log when the server creshes.

Thanks for your work :-).

Well it happend again.
This time I didn't have to restart computer, it was enough to restart gdm.

Last things from log
(II) evaluating device (Generic Keyboard)
(II) XINPUT: Adding extended input device "Generic Keyboard" (type: KEYBOARD)
(II) evaluating device (Configured Mouse)
(II) XINPUT: Adding extended input device "Configured Mouse" (type: MOUSE)
(II) Configured Mouse: ps2EnableDataReporting: succeeded
Could not init font path element /usr/share/fonts/X11/cyrillic, removing from list!
(II) intel(0): xf86UnbindGARTMemory: unbind key 0
(II) intel(0): xf86UnbindGARTMemory: unbind key 1
(II) intel(0): xf86UnbindGARTMemory: unbind key 2
(II) intel(0): xf86UnbindGARTMemory: unbind key 3
(II) intel(0): xf86UnbindGARTMemory: unbind key 4

Created attachment 17989 [details]
Actual Xorg.log

Actual Xorg.log.
Btw: it's strange that it loads dri, although I comment it out. How to disable loading it?
(II) "dri" will be loaded by default.
...
(II) LoadModule: "dri"
...
(II) Loading /usr/lib/xorg/modules/extensions//libdri.so
(II) Module dri: vendor="X.Org Foundation"
	compiled for 1.4.99.906, module version = 1.0.0
	ABI class: X.Org Server Extension, version 1.1
(II) Loading extension XFree86-DRI
...
(II) LoadModule: "intel"

(II) Loading /usr/lib/xorg/modules/drivers//intel_drv.so
(II) Module intel: vendor="X.Org Foundation"
	compiled for 1.4.99.905, module version = 2.4.0
	Module class: X.Org Video Driver
	ABI class: X.Org Video Driver, version 4.1

Created attachment 17990 [details]
Actual Xorg config file

Just in case I send actual Xorg config file.

Sorry I missed that last update, looks like it happens even with render acceleration disabled...  To disable DRI you'd need to also add Option "DRI" "false" to your "device" section (just like you did for exanocomposite).

How quickly can you reproduce the problem?

(In reply to comment #13)
> Sorry I missed that last update, looks like it happens even with render
> acceleration disabled...  To disable DRI you'd need to also add Option "DRI"
> "false" to your "device" section (just like you did for exanocomposite).
> 
> How quickly can you reproduce the problem?
> 

I put it into the configuration. But I already got new graphics card (nv), so I'm not going to use this driver any more, unless there is an easy way howto work with both cards.

The trouble is that I don't know how to reproduce the problem. It just happens sometimes. It haven't occurred since last time.

I have to mark this as a dup of a similar bug as we can't receive enough information from bug reporter. 

*** This bug has been marked as a duplicate of bug 16780 ***