Tonight I finally believe i found the cause of the bug I'd been trying to track down. I wrote a patch, verified that I could reproduce the problem on the latest kernel without the patch applied, then couldn't with it applied, wrote an explanation of the problem, where it originated, the symptoms, and how I'd fixed it, and shipped it off to the people responsible. Hopefully that'll do the job.
Of course while testing I was also reminded of some equally (or perhaps even more) mysterious problems in the same general area. But I should probably work on something else a while before getting back to those....
Sara handed me a Diskworld book ("The Light Fantastic") to read--it's fun, like all of them, and a little different from the ones I've last read, which were among his more recent.
I finally got around to placing an order with REI for a replacement for my old panniers. They look big, and nifty, and very, very yellow. They're also expensive as heck, so I hope they work out a little better than the last ones.