I ran into this trying 2.6.27-rc3 today:

[6.461876] kernel BUG at mm/vmalloc.c:217!

(full boot log attached)

I bisected it to:

git-bisect bad 1c89ac55017f982355c7761e1c912c88c941483d

which is:

commit 1c89ac55017f982355c7761e1c912c88c941483d
Merge: 88fa08f... b1b135c...
Author: Linus Torvalds <torvalds@linux-foundation.org>
Date:   Tue Aug 12 08:40:19 2008 -0700

    Merge
git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus

    *
git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus:
      fix spinlock recursion in hvc_console
      stop_machine: remove unused variable
      modules: extend initcall_debug functionality to the module loader
      export virtio_rng.h
      lguest: use get_user_pages_fast() instead of get_user_pages()
      mm: Make generic weak get_user_pages_fast and EXPORT_GPL it
      lguest: don't set MAC address for guest unless specified

Backing out to the previous commit boots just fine. I've attached the
boot.log, config file, lspci.txt and git-bisect-log. If there is
anything else I can do, I'd be happy to oblige, but I'm checking out
right now. I'll check in tomorrow morning (Eastern USA).

Alan