ext2fs related panic

With kernel sources from yesterday I get a panic as soon as I do this:

mount /mnt/stuff
ls /mnt/stuff

The correspoding line in fstab is this (I haven't checked yet if it also
happens on rw mounted ext2fs)
/dev/ad1s1              /mnt/stuff      ext2fs  ro

Unfortunately I had problems when debugging the core with kgdb (maybe
because it couldn't find symbols for the modules or because I had to
call doadump by hand).

Anyway, here is a (shortened) transcript from ddb output.

Fatal trap 12: page fault while in kernel mode
...
current process = 815 (ls)

trace
ext2_strategy()
bufstrategy()
breadn()
bread()
ext2_read()
ext2_readdir()
getdirentries()
Xint0x80_syscall()

I can provide more info if needed.

Thanks