This bit us a few kernels ago, and for some reason never made it's way
upstream.

https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=144743
Kernel panic - not syncing: drivers/ide/pci/piix.c:231:
spin_lock(drivers/ide/ide.c:c03cef28) already locked by driver/ide/ide-iops.c/1153.
Signed-off-by: Dave Jones <davej@redhat.com>
Cc: Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl>
Cc: Dave Jones <davej@redhat.com>
Cc: Jens Axboe <axboe@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>