Kernel 4.2-rc8 has been released, but does not include the ‘GPL-only’ patch for NVIDIA:  http://lkml.iu.edu/hypermail/linux/kernel/1508.3/00008.html

FATAL: modpost: GPL-incompatible module nvidia.ko uses GPL-only symbol 'flush_workqueue'

A patch was proposed (for -rc5..) but has still not been incorporated:  http://lkml.iu.edu/hypermail/linux/kernel/1508.2/02297.html

Details of the patch are here:  http://lkml.iu.edu/hypermail/linux/kernel/1508.0/02260.html

Hopefully this patch will be included with 4.2 Final, but there is a possibility that this release will need an additional patch for NVIDIA..

Robert Gadsdon.   August 24, 2015.