The "bad things" error is a message that happens when the memory manager
gets a request for a page not in the users process-space, which
shouldn't be possible (as those errors should be trapped by the
segmentation handler). However, ptrace() does some mucking around with
the memory, and it had a bug (now fixed, I hope) that is probably the
reason for this. I'm happy most of it seems to work, though.
Linus