Ahh, the md driver does indeed do something like this. The md driver
will clear the lock bit without ever waking up anybody that waits on it,
as far as I can tell.
I will consider this an md bug until you tell me that you aren't
actually using raid at all, at which point I'll go back to scratching my
head.
Anyway, Ingo, Miguel and Gadi - regardless of whether Stephen does
indeed use md or not, there does seem to be a bug in the raid drivers,
where they just clear the locked bit (grep for "BH_Lock" and you'll see
it quite clearly) without trying to wake anybody up. Please send me
patches,
Linus