Using the attached config (run through oldconfig and holding down
enter), 2.6.38 boots but current -git hangs.  I've bisected it to this
commit:

7eaceaccab5f40bbfda044629a6298616aeaed50 is the first bad commit
commit 7eaceaccab5f40bbfda044629a6298616aeaed50
Author: Jens Axboe <jaxboe@fusionio.com>
Date:   Thu Mar 10 08:52:07 2011 +0100

    block: remove per-queue plugging

    Code has been converted over to the new explicit on-stack plugging,
    and delay users have been converted to use the new API for that.
    So lets kill off the old plugging along with aops->sync_page().

    Signed-off-by: Jens Axboe <jaxboe@fusionio.com>

I suspect it broke CONFIG_IDE_GD_ATA.  (The symptoms change a bit in
later versions, when that was first introduced it hung right after
discovering hda, now it makes it to freeing kernel memory and then hangs
trying to launch init.  But "the disk hangs a lot" still seems to
describe the problem.)

Rob