Bug#832775: OK to close
I forgot about the '-forever' parameter. From 'man x11vnc': Keep listening for more connections rather than exiting as soon as the first client(s) disconnect. Same as -many Working as designed, sorry for the noise. OK to close.
Bug#832775: OK to close, this is a kernel bug
The same stack trace appears at boot time. Bug filed against 'linux-image-686-pae': https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=832905