[LTP] [PATCH v6 2/2] userfaultfd: Add new test using UFFDIO_CONTINUE

[Ricardo Branco]

On 5/5/26 4:12 PM, Cyril Hrubis wrote:
>> +static void run(void)
>> +{
>> +	pthread_t thr;
>> +	struct uffdio_api uffdio_api = {};
>> +	struct uffdio_register uffdio_register;
>> +
>> +	set_pages();
>> +
>> +	uffd = SAFE_USERFAULTFD(O_CLOEXEC | O_NONBLOCK, true);
>> +	uffdio_api.api = UFFD_API;
>> +	uffdio_api.features = 0;
>> +	SAFE_IOCTL(uffd, UFFDIO_API, &uffdio_api);
>> +	if (!(uffdio_api.features & UFFD_FEATURE_MINOR_SHMEM))
>> +		tst_brk(TCONF, "UFFD_FEATURE_MINOR_SHMEM not supported");
>> +	SAFE_CLOSE(uffd);
>> +
>> +	uffd = SAFE_USERFAULTFD(O_CLOEXEC | O_NONBLOCK, false);
>> +
>> +	uffdio_api.api = UFFD_API;
>> +	uffdio_api.features = UFFD_FEATURE_MINOR_SHMEM;
>> +
>> +	SAFE_IOCTL(uffd, UFFDIO_API, &uffdio_api);
>> +
>> +	uffdio_register.range.start = (unsigned long) page;
>> +	uffdio_register.range.len = page_size;
>> +	uffdio_register.mode = UFFDIO_REGISTER_MODE_MINOR;
>> +
>> +	SAFE_IOCTL(uffd, UFFDIO_REGISTER, &uffdio_register);
>> +
>> +	/*
>> +	 * Drop PTEs while retaining the cached shmem page so the next access
>> +	 * faults in MINOR mode.
>> +	 */
>> +	if (madvise(page, page_size, MADV_DONTNEED) < 0)
>> +		tst_brk(TBROK | TERRNO, "madvise MADV_DONTNEED failed");
>> +
>> +	SAFE_PTHREAD_CREATE(&thr, NULL, (void *) handle_thread, NULL);
>> +
>> +	char c = page[0];
>> +
>> +	if (c == 'Z')
>> +		tst_res(TPASS, "Pagefault handled via UFFDIO_CONTINUE");
>> +	else
>> +		tst_res(TFAIL, "pagefault not handled via UFFDIO_CONTINUE, got '%c'", c);
>> +
>> +	SAFE_PTHREAD_JOIN(thr, NULL);
>> +	reset_pages();
>> +}
>> +
>> +static struct tst_test test = {
>> +	.test_all = run,
>> +	/*
>> +	 * UFFDIO_CONTINUE is available since 5.13 but
>> +	 * UFFD_FEATURE_MINOR_SHMEM appeared in 5.14
>> +	 */
>> +	.min_kver = "5.14",
> Should we do a runtime check in the test setup here as well?

We're checking for UFFD_FEATURE_MINOR_SHMEM  it the 2 step handshake.

Cheers,
R