uffd_reg 494 tools/testing/selftests/vm/userfaultfd.c struct uffdio_register uffd_reg; uffd_reg 535 tools/testing/selftests/vm/userfaultfd.c uffd_reg.range.start = msg.arg.remove.start; uffd_reg 536 tools/testing/selftests/vm/userfaultfd.c uffd_reg.range.len = msg.arg.remove.end - uffd_reg 538 tools/testing/selftests/vm/userfaultfd.c if (ioctl(uffd, UFFDIO_UNREGISTER, &uffd_reg.range))