On Mon, Apr 12, 2021 at 10:17:19PM -0700, Axel Rasmussen wrote:
> Currently, the context (fds, mmap-ed areas, etc.) are global. Each test
> mutates this state in some way, in some cases really "clobbering it"
> (e.g., the events test mremap-ing area_dst over the top of area_src, or
> the minor faults tests overwriting the count_verify values in the test
> areas). We run the tests in a particular order, each test is careful to
> make the right assumptions about its starting state, etc.
>
> But, this is fragile. It's better for a test's success or failure to not
> depend on what some other prior test case did to the global state.
>
> To that end, clear and reinitialize the test context at the start of
> each test case, so whatever prior test cases did doesn't affect future
> tests.
>
> This is particularly relevant to this series because the events test's
> mremap of area_dst screws up assumptions the minor fault test was
> relying on. This wasn't a problem for hugetlb, as we don't mremap in
> that case.
>
> Signed-off-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx>
> ---
> tools/testing/selftests/vm/userfaultfd.c | 221 +++++++++++++----------
> 1 file changed, 127 insertions(+), 94 deletions(-)
>
> diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c
> index 1f65c4ab7994..0ff01f437a39 100644
> --- a/tools/testing/selftests/vm/userfaultfd.c
> +++ b/tools/testing/selftests/vm/userfaultfd.c
> @@ -89,7 +89,8 @@ static int shm_fd;
> static int huge_fd;
> static char *huge_fd_off0;
> static unsigned long long *count_verify;
> -static int uffd, uffd_flags, finished, *pipefd;
> +static int uffd = -1;
> +static int uffd_flags, finished, *pipefd;
> static char *area_src, *area_src_alias, *area_dst, *area_dst_alias;
> static char *zeropage;
> pthread_attr_t attr;
> @@ -342,6 +343,121 @@ static struct uffd_test_ops hugetlb_uffd_test_ops = {
>
> static struct uffd_test_ops *uffd_test_ops;
>
> +static int userfaultfd_open(uint64_t *features)
> +{
> + struct uffdio_api uffdio_api;
> +
> + uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK);
Keep UFFD_USER_MODE_ONLY?
[...]
> @@ -961,10 +1045,9 @@ static int userfaultfd_zeropage_test(void)
> printf("testing UFFDIO_ZEROPAGE: ");
> fflush(stdout);
>
> - uffd_test_ops->release_pages(area_dst);
> -
> - if (userfaultfd_open(0))
> + if (uffd_test_ctx_clear() || uffd_test_ctx_init(0))
> return 1;
Would it look even nicer to init() at the entry of each test, and clear() after
finish one test?
> +
> uffdio_register.range.start = (unsigned long) area_dst;
> uffdio_register.range.len = nr_pages * page_size;
> uffdio_register.mode = UFFDIO_REGISTER_MODE_MISSING;
The rest looks good to me. Thanks,
--
Peter Xu
