Re: [PATCH v2 5/6] userfaultfd: selftests: make /dev/userfaultfd testing configurable

On 4/22/22 3:29 PM, Axel Rasmussen wrote:

Instead of always testing both userfaultfd(2) and /dev/userfaultfd, let the user choose which to test.

As with other test features, change the behavior based on a new command line flag. Introduce the idea of "test mods", which are generic (not specific to a test type) modifications to the behavior of the test. This is sort of borrowed from this RFC patch series [1], but simplified a bit.

The benefit is, in "typical" configurations this test is somewhat slow (say, 30sec or something). Testing both clearly doubles it, so it may not always be desirable, as users are likely to use one or the other, but never both, in the "real world".

Signed-off-by: Axel Rasmussen axelrasmussen@google.com

tools/testing/selftests/vm/userfaultfd.c | 41 +++++++++++++++++------- 1 file changed, 30 insertions(+), 11 deletions(-)

diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c index 12ae742a9981..274522704e40 100644 --- a/tools/testing/selftests/vm/userfaultfd.c +++ b/tools/testing/selftests/vm/userfaultfd.c @@ -142,8 +142,17 @@ static void usage(void) { fprintf(stderr, "\nUsage: ./userfaultfd <test type> <MiB> <bounces> " "[hugetlbfs_file]\n\n");

Remove the extra blank line here.

fprintf(stderr, "Supported <test type>: anon, hugetlb, " "hugetlb_shared, shmem\n\n");

Remove the extra blank line here.

• fprintf(stderr, "'Test mods' can be joined to the test type string with a ':'. "

• "Supported mods:\n");
  

• fprintf(stderr, "\tdev - Use /dev/userfaultfd instead of userfaultfd(2)\n");
• fprintf(stderr, "\nExample test mod usage:\n");
• fprintf(stderr, "# Run anonymous memory test with /dev/userfaultfd:\n");
• fprintf(stderr, "./userfaultfd anon:dev 100 99999\n\n");
• fprintf(stderr, "Examples:\n\n"); fprintf(stderr, "%s", examples);

Update examples above with new test cases if any.

exit(1); @@ -1610,8 +1619,6 @@ unsigned long default_huge_page_size(void) static void set_test_type(const char *type) {

• uint64_t features = UFFD_API_FEATURES;
• if (!strcmp(type, "anon")) { test_type = TEST_ANON; uffd_test_ops = &anon_uffd_test_ops;

@@ -1631,10 +1638,28 @@ static void set_test_type(const char *type) test_type = TEST_SHMEM; uffd_test_ops = &shmem_uffd_test_ops; test_uffdio_minor = true;

• } else {

• err("Unknown test type: %s", type);
  

• }

At this point, it might make it so much easier and maintainable if we were to use getopt instead of parsing options.

+}

+static void parse_test_type_arg(const char *raw_type) +{

• char *buf = strdup(raw_type);
• uint64_t features = UFFD_API_FEATURES;
• while (buf) {

• const char *token = strsep(&buf, ":");
  

• if (!test_type)
  

• 	set_test_type(token);
  

• else if (!strcmp(token, "dev"))
  

• 	test_dev_userfaultfd = true;
  

• else
  

• 	err("unrecognized test mod '%s'", token);
  

  }

• if (!test_type)

• err("failed to parse test type argument: '%s'", raw_type);
  

• if (test_type == TEST_HUGETLB) page_size = default_huge_page_size(); else

@@ -1681,7 +1706,7 @@ int main(int argc, char **argv) err("failed to arm SIGALRM"); alarm(ALARM_INTERVAL_SECS);

• set_test_type(argv[1]);

• parse_test_type_arg(argv[1]);

nr_cpus = sysconf(_SC_NPROCESSORS_ONLN); nr_pages_per_cpu = atol(argv[2]) * 1024*1024 / page_size / @@ -1719,12 +1744,6 @@ int main(int argc, char **argv) } printf("nr_pages: %lu, nr_pages_per_cpu: %lu\n", nr_pages, nr_pages_per_cpu);

• test_dev_userfaultfd = false;
• if (userfaultfd_stress())

• return 1;
  

• test_dev_userfaultfd = true; return userfaultfd_stress(); }

Same comments as before on fail vs. skip conditions to watch out for and report them correctly.

thanks, -- Shuah