#define __user __attribute__((address_space(1))) extern int poke_memory(void *addr); static int sys_do_stuff(void __user *user_addr) { return poke_memory(user_addr); } /* * check-name: address_space attribute * * check-error-start address_space.c:7:28: warning: incorrect type in argument 1 (different address spaces) address_space.c:7:28: expected void *addr address_space.c:7:28: got void *user_addr * check-error-end */