Module licenses

Loadable modules now declare their licenses
MODULE_LICENSE("GPL");
MODULE_LICENSE("Dual MPL/GPL");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_LICENSE("Proprietary - first born son required");

Non-free licenses "taint" the kernel
/proc/sys/kernel/tainted is non-zero
Tainted flag shown in oops listings

The purpose?
Allow kernel hackers to filter bug reports