From: Axel Rasmussen <axelrasmussen@xxxxxxxxxx> Subject: userfaultfd/selftests: exercise minor fault handling shmem support Enable test_uffdio_minor for test_type == TEST_SHMEM, and modify the test slightly to pass in / check for the right feature flags. Link: https://lkml.kernel.org/r/20210503180737.2487560-11-axelrasmussen@xxxxxxxxxx Signed-off-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx> Reviewed-by: Peter Xu <peterx@xxxxxxxxxx> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: Brian Geffon <bgeffon@xxxxxxxxxx> Cc: "Dr . David Alan Gilbert" <dgilbert@xxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Jerome Glisse <jglisse@xxxxxxxxxx> Cc: Joe Perches <joe@xxxxxxxxxxx> Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx> Cc: Lokesh Gidra <lokeshgidra@xxxxxxxxxx> Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Mike Rapoport <rppt@xxxxxxxxxxxxxxxxxx> Cc: Mina Almasry <almasrymina@xxxxxxxxxx> Cc: Oliver Upton <oupton@xxxxxxxxxx> Cc: Shaohua Li <shli@xxxxxx> Cc: Shuah Khan <shuah@xxxxxxxxxx> Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> Cc: Wang Qing <wangqing@xxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- tools/testing/selftests/vm/userfaultfd.c | 29 ++++++++++++++++++--- 1 file changed, 25 insertions(+), 4 deletions(-) --- a/tools/testing/selftests/vm/userfaultfd.c~userfaultfd-selftests-exercise-minor-fault-handling-shmem-support +++ a/tools/testing/selftests/vm/userfaultfd.c @@ -474,6 +474,7 @@ static void wp_range(int ufd, __u64 star static void continue_range(int ufd, __u64 start, __u64 len) { struct uffdio_continue req; + int ret; req.range.start = start; req.range.len = len; @@ -482,6 +483,17 @@ static void continue_range(int ufd, __u6 if (ioctl(ufd, UFFDIO_CONTINUE, &req)) err("UFFDIO_CONTINUE failed for address 0x%" PRIx64, (uint64_t)start); + + /* + * Error handling within the kernel for continue is subtly different + * from copy or zeropage, so it may be a source of bugs. Trigger an + * error (-EEXIST) on purpose, to verify doing so doesn't cause a BUG. + */ + req.mapped = 0; + ret = ioctl(ufd, UFFDIO_CONTINUE, &req); + if (ret >= 0 || req.mapped != -EEXIST) + err("failed to exercise UFFDIO_CONTINUE error handling, ret=%d, mapped=%" PRId64, + ret, (int64_t) req.mapped); } static void *locking_thread(void *arg) @@ -1182,7 +1194,7 @@ static int userfaultfd_minor_test(void) void *expected_page; char c; struct uffd_stats stats = { 0 }; - uint64_t features = UFFD_FEATURE_MINOR_HUGETLBFS; + uint64_t req_features, features_out; if (!test_uffdio_minor) return 0; @@ -1190,9 +1202,17 @@ static int userfaultfd_minor_test(void) printf("testing minor faults: "); fflush(stdout); - uffd_test_ctx_init_ext(&features); - /* If kernel reports the feature isn't supported, skip the test. */ - if (!(features & UFFD_FEATURE_MINOR_HUGETLBFS)) { + if (test_type == TEST_HUGETLB) + req_features = UFFD_FEATURE_MINOR_HUGETLBFS; + else if (test_type == TEST_SHMEM) + req_features = UFFD_FEATURE_MINOR_SHMEM; + else + return 1; + + features_out = req_features; + uffd_test_ctx_init_ext(&features_out); + /* If kernel reports required features aren't supported, skip test. */ + if ((features_out & req_features) != req_features) { printf("skipping test due to lack of feature support\n"); fflush(stdout); return 0; @@ -1575,6 +1595,7 @@ static void set_test_type(const char *ty map_shared = true; test_type = TEST_SHMEM; uffd_test_ops = &shmem_uffd_test_ops; + test_uffdio_minor = true; } else { err("Unknown test type: %s", type); } _
