2.6.23-rc1 regression: mm: fix fault vs invalidate race for linear mappings

["Bret Towe" <magnade@gmail.com>]

for a while in -git I've had an issue that on boot when gdm loads the
screen stays black
using ctrl-f1 doesn't return to a console and killing X doesn't help any
ssh'ing into the box does work top only shows 100% io-wait
dmesg shows nothing odd

the work around I have is at the moment is to just move the radeon drm module
out of the way so it doesn't load on boot and X works just fine like that
I did some bisecting which took a few days and tracked it down to
commit d00806b183152af6d24f46f0c33f14162ca1262a

its way to complex for me to revert it on top of -rc1 to verify that's
the issue tho
I keep forgetting to get a trace of what its waiting on when I'm in that kernel
I assume that would be of use and Ill get that later

the box this is happening on is a g4 mac mini the built in card is a radeon 9200
I'm not seeing any issues on an amd64 box with radeon card it's also a 9600 tho