The diff makes a change in mm/memory.c, which fixes the horrible crash I had when using ALSA. A good way to trigger this bug is to use mpg321 in the console. The kernel BUG is instant. Please modify the ebuild to apply the diff I have attached, so mm-sources users can have proper sound support again :)
Created attachment 21039 [details, diff] The diff from LKML, but then with Gentoo-compatible paths.
Applying, going to leave bug open for a while after committing so that people can see it.
mm-sources-2.6.0-test9-mm5 is out so I'm going to close this.