What does this dtrace error mean?

According to this blog post (with more information here), it's caused by iTunes, which DTrace "filters" so it can't be used to try to break iTunes' DRM.

Quitting iTunes resolves the error.

The errors are getting output to stderr, and can be filtered out by running the command as such:

sudo iotop -C 5 12 2>/dev/null

This does have the side effect of filtering out any other errors that might come up. I've found it to be an ok tradeoff, in that it's made my iotop output readable.

I'm not sure what the cause of the errors are, unfortunately. I've searched, but have not been able to find anything as of yet.