I’ve actually made a number of changes after my original patch in the past month or so to fix a number of problems with page faults from the original patch. These page faults were caused by a null pointer in thread structures during forking. It seems to be fairly easy to demonstrate this issue by executing any program that does a decent amount of forking from inside a jail. I’m not exactly sure why these values are null, but it seems to be well outside the context of these patches. I added some simple checks for this null value and that seems to have cleared things up.
[Patch no longer available as of 02/29/2016]. It applies against the original version of src/sys/kern/kern_jail.c so you will need to revert it if you had previously tried to patch it.
I’ve done this work on 6.2 so I can’t say if this patch will work on other versions. This patch also includes the changes to get memory limits to be displayed. Let me know how it goes.