Kernel panic - Linux - hardware or software?

Got a kernel panic this morning on a ThinkCentre desktop running Debian 8 32-bit, trigger seemed to be opening a new tab in Firefox, not the first time a seemingly minor operation has triggered a panic on this system...

Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b

CPU: 0 PID: 1 Comm: systemd Tainted: P        0  3.16.0-4-686-pae #1 Debian 3.16.7-ckt25-2+deb8u3
Hardware name: IBM 8113F4U/IBM, BIOS 2EKT36AUS 04/04/2006
 00000000 f4c6fe28 c1479ea7 ...
Call Trace:
 [<c1479ea7>] ? dump_stack+0x55/0x6e
 [<c147771c>] ? panic+0x87/0x1af
 ...
 [<c104be80>] ? __do_page_fault+0x4d0/0x4d0
 ...

If I read that right, the system was in the middle of trying to swap a page out. Why would that lead to an attempt to kill init? Is there something I can tune to protect init better?