Regression introduced in drm/i915 kernel modules for 965GM system

[Richard Goedeken]

I recently noticed a massive memory leak somewhere in the OpenGL software stack, 
so I decided to update everything and rebuild from the tip again.  I did that 
and discovered a new bug.  After running an OpenGL program a few times, the 
system becomes extremely slow (even after the OpenGL program is terminated).  I 
can watch X/Gnome redraw the windows when I switch between desktops.  I ran an 
OProfile session and it seems the CPU time is being eaten inside the kernel. 
Unfortunately Fedora 8 doesn't provide a vmlinux image, and building a Fedora 
kernel is a 30-step process or so (thanks, RPM), so I don't have any more detail 
than this.

I found that I could bring the system back to its normal responsiveness by doing 
'telinit 3' and then 'rmmod i915' and 'rmmod drm'.  When I removed i915.ko it 
took a very long time and spit out a message "kernel: Disabling IRQ #16".  Then 
I brought back X with 'telinit 5' and it was fast as usual.  So the problem 
seems to be in the drm or i915 kernel module.

Richard