On my Dell Latitude e4300 commit 859ddf0974 ("idr: fix a critical
misallocation bug") causes Xorg to segfault with the following
backtrace:

...
(II) intel(0): Initializing HW Cursor
(II) intel(0): No memory allocations

Backtrace:
0: /usr/bin/X11/X(xorg_backtrace+0x26) [0x4f00c6]
1: /usr/bin/X11/X(xf86SigHandler+0x41) [0x4852c1]
2: /lib/libc.so.6 [0x7fbdad071530]
3: /usr/lib/xorg/modules/drivers//intel_drv.so [0x7fbdab8a1cbd]
4: /usr/lib/xorg/modules/drivers//intel_drv.so(gen4_render_state_init+0x416) [0x
7fbdab8a2a36]
5: /usr/lib/xorg/modules/drivers//intel_drv.so [0x7fbdab87d3e8]
6: /usr/lib/xorg/modules/drivers//intel_drv.so [0x7fbdab87e6fb]
7: /usr/bin/X11/X(AddScreen+0x1d4) [0x4337c4]
8: /usr/bin/X11/X(InitOutput+0x76f) [0x46f27f]
9: /usr/bin/X11/X(main+0x1fe) [0x433ece]
10: /lib/libc.so.6(__libc_start_main+0xfd) [0x7fbdad05cabd]
11: /usr/bin/X11/X [0x433509]
Saw signal 11.  Server aborting.

Reverting commit 859ddf0974 causes X to start working again -- tested on
top of c80d292f.

I'm running Karmic 64-bit with

xserver-xorg-core                    2:1.6.4-2ubuntu4.1
xserver-xorg-video-intel             2:2.9.0-1ubuntu2.1
libdrm-intel1                        2.4.14-1ubuntu1
libdrm2                              2.4.14-1ubuntu1

More information (dmesg, lspci, full dpkg, etc) is available at
http://web.hexapodia.org/~adi/bugs/201002-xorg-segv/

I've attached my kconfig as that seems like the most likely difference
between my config and others who are (presumably?) not seeing this
crash.  (Gzipped, alas, because AFAIK 70KB will exceed vger's size
liimit.)

-andy