On Mon, Aug 08, 2022 at 10:56:12AM -0700, Axel Rasmussen wrote: > We clearly want to ensure both userfaultfd(2) and /dev/userfaultfd keep > working into the future, so just run the test twice, using each > interface. > > 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". > > [1]: https://patchwork.kernel.org/project/linux-mm/patch/20201129004548.1619714-14-namit@xxxxxxxxxx/ > > Acked-by: Peter Xu <peterx@xxxxxxxxxx> > Signed-off-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx> With a few nits below Acked-by: Mike Rapoport <rppt@xxxxxxxxxxxxx> > --- > tools/testing/selftests/vm/userfaultfd.c | 69 ++++++++++++++++++++---- > 1 file changed, 60 insertions(+), 9 deletions(-) > > diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c > index 7c3f1b0ab468..cae72867c173 100644 > --- a/tools/testing/selftests/vm/userfaultfd.c > +++ b/tools/testing/selftests/vm/userfaultfd.c > @@ -77,6 +77,11 @@ static int bounces; > #define TEST_SHMEM 3 > static int test_type; > > +#define UFFD_FLAGS (O_CLOEXEC | O_NONBLOCK | UFFD_USER_MODE_ONLY) > + > +/* test using /dev/userfaultfd, instead of userfaultfd(2) */ > +static bool test_dev_userfaultfd; > + > /* exercise the test_uffdio_*_eexist every ALARM_INTERVAL_SECS */ > #define ALARM_INTERVAL_SECS 10 > static volatile bool test_uffdio_copy_eexist = true; > @@ -125,6 +130,8 @@ struct uffd_stats { > const char *examples = > "# Run anonymous memory test on 100MiB region with 99999 bounces:\n" > "./userfaultfd anon 100 99999\n\n" > + "# Run the same anonymous memory test, but using /dev/userfaultfd:\n" > + "./userfaultfd anon:dev 100 99999\n\n" > "# Run share memory test on 1GiB region with 99 bounces:\n" > "./userfaultfd shmem 1000 99\n\n" > "# Run hugetlb memory test on 256MiB region with 50 bounces:\n" > @@ -141,6 +148,14 @@ static void usage(void) > "[hugetlbfs_file]\n\n"); > fprintf(stderr, "Supported <test type>: anon, hugetlb, " > "hugetlb_shared, shmem\n\n"); > + fprintf(stderr, "'Test mods' can be joined to the test type string with a ':'. " > + "Supported mods:\n"); > + fprintf(stderr, "\tsyscall - Use userfaultfd(2) (default)\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); > exit(1); > @@ -154,12 +169,14 @@ static void usage(void) > ret, __LINE__); \ > } while (0) > > -#define err(fmt, ...) \ > +#define errexit(exitcode, fmt, ...) \ > do { \ > _err(fmt, ##__VA_ARGS__); \ > - exit(1); \ > + exit(exitcode); \ > } while (0) > > +#define err(fmt, ...) errexit(1, fmt, ##__VA_ARGS__) > + > static void uffd_stats_reset(struct uffd_stats *uffd_stats, > unsigned long n_cpus) > { > @@ -383,13 +400,29 @@ static void assert_expected_ioctls_present(uint64_t mode, uint64_t ioctls) > } > } > > +static int __userfaultfd_open_dev(void) > +{ > + int fd, _uffd = -1; Nit: the initialization here is not necessary, _uffd is always set from ioctl() return value. > + > + fd = open("/dev/userfaultfd", O_RDWR | O_CLOEXEC); > + if (fd < 0) > + return -1; > + > + _uffd = ioctl(fd, USERFAULTFD_IOC_NEW, UFFD_FLAGS); > + close(fd); > + return _uffd; > +} > + > static void userfaultfd_open(uint64_t *features) > { > struct uffdio_api uffdio_api; > > - uffd = syscall(__NR_userfaultfd, O_CLOEXEC | O_NONBLOCK | UFFD_USER_MODE_ONLY); > + if (test_dev_userfaultfd) > + uffd = __userfaultfd_open_dev(); > + else > + uffd = syscall(__NR_userfaultfd, UFFD_FLAGS); > if (uffd < 0) > - err("userfaultfd syscall not available in this kernel"); > + errexit(KSFT_SKIP, "creating userfaultfd failed"); I'm not sure if this should be KSFT_SKIP. If creation of uffd failed because anything except ENOSYS I'd consider the test failing. > uffd_flags = fcntl(uffd, F_GETFD, NULL); > > uffdio_api.api = UFFD_API; > @@ -1584,8 +1617,6 @@ 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; > @@ -1603,9 +1634,29 @@ 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); > } > +} > + > +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 if (!strcmp(token, "syscall")) > + test_dev_userfaultfd = false; > + 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(); > @@ -1653,7 +1704,7 @@ 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 / > -- > 2.37.1.559.g78731f0fdb-goog > -- Sincerely yours, Mike.
