On Wed, Aug 10, 2022 at 11:38 PM Mike Rapoport <rppt@xxxxxxxxxx> wrote: > > 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> Thanks for reviewing, Mike! > > > --- > > 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. Agreed. > > > + > > + 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. Agreed, but looking at it I think it's more complicated. In __userfaultfd_open_dev, I think: - If we fail to open /dev/userfaultfd for any reason, that's a KSFT_SKIP - If USERFAULTFD_IOC_NEW returns ENOTTY that's a KSFT_SKIP, otherwise a real test failure. But then for syscall(__NR_userfaultfd, ...), I think ENOSYS is a KSFT_SKIP, but any other errno is a real test failure. I'll send an updated version which has those semantics. I think to do so we need to move some of the error handling into __userfaultfd_open_dev, instead of having its caller do it. > > > 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.
