Test spurious ENOENT which occurs when it tried to start pagination from an inactivated or destroyed namespace. The new test is almost identical to pagination_with_type_filter, except that it calls run_noisy_children() which creates and lists namespaces to disturb nstree.
As far as the author tested, this bug only reproduced on a baremetal environment, probably because the test relies on the RCU behavior and the kernel behaves differently on VM. Signed-off-by: Yohei Kojima <[email protected]> --- .../namespaces/listns_pagination_bug.c | 200 ++++++++++++++++++ 1 file changed, 200 insertions(+) diff --git a/tools/testing/selftests/namespaces/listns_pagination_bug.c b/tools/testing/selftests/namespaces/listns_pagination_bug.c index da7d33f96397..f71d8f4d64bb 100644 --- a/tools/testing/selftests/namespaces/listns_pagination_bug.c +++ b/tools/testing/selftests/namespaces/listns_pagination_bug.c @@ -135,4 +135,204 @@ TEST(pagination_with_type_filter) } } +static void run_noisy_children(int num_workers) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWUSER, /* Filter by user namespace */ + .spare2 = 0, + .user_ns_id = 0, + }; + pid_t pids[num_workers]; + int num_forked = 0; + int i; + + /* + * Create worker processes that do concurrent operations; + * most of this part is borrowed from concurrent_namespace_operations + * test in stress_test.c + */ + for (i = 0; i < num_workers; i++) { + pids[i] = fork(); + if (pids[i] < 0) + goto failure; + if (pids[i] > 0) + num_forked++; + + if (pids[i] == 0) { + /* Each worker: create namespaces, list them, repeat */ + int iterations; + + for (iterations = 0; iterations < 10; iterations++) { + int userns_fd; + __u64 temp_ns_ids[100]; + ssize_t ret; + + /* Create a user namespace */ + userns_fd = get_userns_fd(0, getuid(), 1); + if (userns_fd < 0) + continue; + + /* List namespaces */ + ret = sys_listns(&req, temp_ns_ids, ARRAY_SIZE(temp_ns_ids), 0); + (void)ret; + + close(userns_fd); + + /* Small delay */ + usleep(1000); + } + + exit(0); + } + } + + /* + * Return after waiting for children; this is enough for + * reproduction, and help keeping the test code simple. + */ + for (i = 0; i < num_forked; i++) + waitpid(pids[i], NULL, 0); + + return; + +failure: + for (i = 0; i < num_forked; i++) + kill(pids[i], SIGKILL); + for (i = 0; i < num_forked; i++) + waitpid(pids[i], NULL, 0); +} + +/* + * A test case to reproduce spurious ENOENT in listns pagination + * + * The bug occurs when the ns id to start pagination is inactivated or + * destroyed before listns is called (or during listns is processed). + * + * This test is almost identical to pagination_with_type_filter test + * except that this calls run_noisy_children(). + */ +TEST(pagination_during_grace_period) +{ + struct ns_id_req req = { + .size = sizeof(req), + .spare = 0, + .ns_id = 0, + .ns_type = CLONE_NEWUSER, /* Filter by user namespace */ + .spare2 = 0, + .user_ns_id = 0, + }; + pid_t pids[10]; + int num_children = 10; + const int num_noisy_children = 10; + int i; + int sv[2]; + __u64 first_batch[3]; + ssize_t ret; + + ASSERT_EQ(socketpair(AF_UNIX, SOCK_STREAM, 0, sv), 0); + + run_noisy_children(num_noisy_children); + + /* Create children with user namespaces */ + for (i = 0; i < num_children; i++) { + pids[i] = fork(); + ASSERT_GE(pids[i], 0); + + if (pids[i] == 0) { + char c; + + close(sv[0]); + + if (setup_userns() < 0) { + close(sv[1]); + exit(1); + } + + /* Signal parent we're ready */ + if (write(sv[1], &c, 1) != 1) { + close(sv[1]); + exit(1); + } + + /* Wait for parent signal to exit */ + if (read(sv[1], &c, 1) != 1) { + close(sv[1]); + exit(1); + } + + close(sv[1]); + exit(0); + } + } + + close(sv[1]); + + /* Wait for all children to signal ready */ + for (i = 0; i < num_children; i++) { + char c; + + if (read(sv[0], &c, 1) != 1) { + close(sv[0]); + for (int j = 0; j < num_children; j++) + kill(pids[j], SIGKILL); + for (int j = 0; j < num_children; j++) + waitpid(pids[j], NULL, 0); + ASSERT_TRUE(false); + } + } + + /* First batch - this should work */ + ret = sys_listns(&req, first_batch, 3, 0); + if (ret < 0) { + if (errno == ENOSYS) { + close(sv[0]); + for (i = 0; i < num_children; i++) + kill(pids[i], SIGKILL); + for (i = 0; i < num_children; i++) + waitpid(pids[i], NULL, 0); + SKIP(return, "listns() not supported"); + } + ASSERT_GE(ret, 0); + } + + TH_LOG("First batch returned %zd entries", ret); + + if (ret == 3) { + __u64 second_batch[3]; + + /* Second batch - pagination triggers the bug */ + req.ns_id = first_batch[2]; /* Continue from last ID */ + ret = sys_listns(&req, second_batch, 3, 0); + + TH_LOG("Second batch returned %zd entries", ret); + ASSERT_GE(ret, 0); + } + + /* Signal all children to exit */ + for (i = 0; i < num_children; i++) { + char c = 'X'; + + if (write(sv[0], &c, 1) != 1) { + close(sv[0]); + for (int j = i; j < num_children; j++) + kill(pids[j], SIGKILL); + for (int j = 0; j < num_children; j++) + waitpid(pids[j], NULL, 0); + ASSERT_TRUE(false); + } + } + + close(sv[0]); + + /* Cleanup */ + for (i = 0; i < num_children; i++) { + int status; + + waitpid(pids[i], &status, 0); + } +} + TEST_HARNESS_MAIN -- 2.52.0
