khubd in "uninterruptible sleep"

Curious thing. My load average is hovering around 1.0, but nothing is taking up any CPU time. Makes sense, sort of, as the load average is (I believe) the average number of processes active, and not a measure of CPU usage. So I look at top, and see that no processes are in run state.

But there is one, khubd, that's in D state. The top manual reports that this is "uninterruptable sleep". I Google (of course) for khubd, and find that it's a kernel thread, and a suggestion that removing usbcore will kill it. Curiously enough, I'm not able to automount my USB MP3 player (it worked on my old machine, last week, but not on this one). Probably not a coincidence.

So I go to unload usbcore. usbcore is used by three other modules: usb_storage, usbserial, and uhci_hcd. I remove usbserial; no problem. I rmmod uhci_hcd, and now I have two processes in D mode, the new one being rmmod. Can't kill or kill -9 rmmod; the kernel is serious about the uninterruptible thing. Hrm. Time to reboot?

Bounced my machine, khubd came back, but is now in S mode, or just sleeping. I suppose the next thing to try is plugging in my MP3 player again, and see if that's what wedged khubd.