On my arm64 machine, I get the following failure: ... tester_init:PASS:tester_log_buf 0 nsec process_subtest:PASS:obj_open_mem 0 nsec process_subtest:PASS:specs_alloc 0 nsec serial_test_map_kptr:PASS:rcu_tasks_trace_gp__open_and_load 0 nsec ... test_map_kptr_success:PASS:map_kptr__open_and_load 0 nsec test_map_kptr_success:PASS:test_map_kptr_ref1 refcount 0 nsec test_map_kptr_success:FAIL:test_map_kptr_ref1 retval unexpected error: 2 (errno 2) test_map_kptr_success:PASS:test_map_kptr_ref2 refcount 0 nsec test_map_kptr_success:FAIL:test_map_kptr_ref2 retval unexpected error: 1 (errno 2) ... #201/21 map_kptr/success-map:FAIL In serial_test_map_kptr(), before test_map_kptr_success(), one kern_sync_rcu() is used to have some delay for freeing the map. But in my environment, one kern_sync_rcu() seems not enough and caused the test failure. In bpf_map_free_in_work() in syscall.c, the queue time for queue_work(system_dfl_wq, &map->work) may be longer than expected. This may cause the test failure since test_map_kptr_success() expects all previous maps having been freed. In stead of one kern_sync_rcu() before test_map_kptr_success(), I added two more kern_sync_rcu() to have a longer delay and the test succeeded. Cc: Kumar Kartikeya Dwivedi Signed-off-by: Yonghong Song --- tools/testing/selftests/bpf/prog_tests/map_kptr.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/map_kptr.c b/tools/testing/selftests/bpf/prog_tests/map_kptr.c index 8743df599567..f9cfc4d3153c 100644 --- a/tools/testing/selftests/bpf/prog_tests/map_kptr.c +++ b/tools/testing/selftests/bpf/prog_tests/map_kptr.c @@ -148,11 +148,15 @@ void serial_test_map_kptr(void) ASSERT_OK(kern_sync_rcu_tasks_trace(skel), "sync rcu_tasks_trace"); ASSERT_OK(kern_sync_rcu(), "sync rcu"); + ASSERT_OK(kern_sync_rcu(), "sync rcu"); + ASSERT_OK(kern_sync_rcu(), "sync rcu"); /* Observe refcount dropping to 1 on bpf_map_free_deferred */ test_map_kptr_success(false); ASSERT_OK(kern_sync_rcu_tasks_trace(skel), "sync rcu_tasks_trace"); ASSERT_OK(kern_sync_rcu(), "sync rcu"); + ASSERT_OK(kern_sync_rcu(), "sync rcu"); + ASSERT_OK(kern_sync_rcu(), "sync rcu"); /* Observe refcount dropping to 1 on synchronous delete elem */ test_map_kptr_success(true); } -- 2.47.3