> Not sure what's going on with the i_sem, are you playing with the loopfile
> somehow during the sync?

No. It's sitting in /var/cache/ext3test, and nothing else touches it.

> Can you also try to find more info about c01efe72
> <stext_lock+ee2/273a> with an objdump -j .text.lock? (should be the
> slow path of down() corresponding to the i_sem down in lo_send)

I guess I'm a bit uneducated, but objdump -j .text.lock vmlinux
doesn't work here, I'm obviously doing something wrong.
 
> are you sure it's really related to the loop device? (and not a
> ""genuine"" IDE lockup or something like that)

Yes, I'm sure. Without using the loop device, the system works fine,
as far as I can tell, and even with the loop device, 2.4.14 is OK.