On non-mainstream kernels the parameters of the kernel function access_ok() may differ.

Then add

CFLAGS_MODULE=-DHAVE_ACCESS_OK_TYPE=1

or

CFLAGS_MODULE=-DHAVE_ACCESS_OK_TYPE=0

to the makefile

modules:
	$(MAKE) -C $(KERNELDIR) M=$(shell pwd) CFLAGS_MODULE=-DHAVE_ACCESS_OK_TYPE=1 modules