Now is probably a good time to check your memory; the kernel should never crash due to the behaviour of an application. Given where the kernel BUG happened (most of the BUG() calls in page_alloc.c are sanity checks) , and the fact that ImageMagick was using a large amount of memory at the time, there's a good chance that your memory is flakey.
sudo /usr/sbin/memtest all 32 --log <snip> 32 runs completed. 0 errors detected. Total runtime: 51719 seconds.
Which of course doesn't guarantee that the memory is good. Perhaps I'll try on another machine/OS combination.
Cheers, Roy.
