From: Yonghong Song Date: Fri, 16 Jan 2026 05:22:45 +0000 (-0800) Subject: selftests/bpf: Fix map_kptr test failure X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=efad162f5a840ae178e7761c176c49f433c7bb68;p=thirdparty%2Fkernel%2Flinux.git selftests/bpf: Fix map_kptr test failure 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. Since it is not clear how long queue_work() time takes, a bpf prog is added to count the reference after bpf_kfunc_call_test_acquire(). If the number of references is 2 (for initial ref and the one just acquired), all previous maps should have been released. This will resolve the above 'retval unexpected error' issue. Signed-off-by: Yonghong Song Signed-off-by: Andrii Nakryiko Acked-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/bpf/20260116052245.3692405-1-yonghong.song@linux.dev --- diff --git a/tools/testing/selftests/bpf/prog_tests/map_kptr.c b/tools/testing/selftests/bpf/prog_tests/map_kptr.c index 8743df5995673..f372162c0280c 100644 --- a/tools/testing/selftests/bpf/prog_tests/map_kptr.c +++ b/tools/testing/selftests/bpf/prog_tests/map_kptr.c @@ -131,6 +131,25 @@ static int kern_sync_rcu_tasks_trace(struct rcu_tasks_trace_gp *rcu) return 0; } +static void wait_for_map_release(void) +{ + LIBBPF_OPTS(bpf_test_run_opts, lopts); + struct map_kptr *skel; + int ret; + + skel = map_kptr__open_and_load(); + if (!ASSERT_OK_PTR(skel, "map_kptr__open_and_load")) + return; + + do { + ret = bpf_prog_test_run_opts(bpf_program__fd(skel->progs.count_ref), &lopts); + ASSERT_OK(ret, "count_ref ret"); + ASSERT_OK(lopts.retval, "count_ref retval"); + } while (skel->bss->num_of_refs != 2); + + map_kptr__destroy(skel); +} + void serial_test_map_kptr(void) { struct rcu_tasks_trace_gp *skel; @@ -148,11 +167,15 @@ 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"); + wait_for_map_release(); + /* 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"); + wait_for_map_release(); + /* Observe refcount dropping to 1 on synchronous delete elem */ test_map_kptr_success(true); } diff --git a/tools/testing/selftests/bpf/progs/map_kptr.c b/tools/testing/selftests/bpf/progs/map_kptr.c index edaba481db9d8..e708ffbe1f610 100644 --- a/tools/testing/selftests/bpf/progs/map_kptr.c +++ b/tools/testing/selftests/bpf/progs/map_kptr.c @@ -487,6 +487,24 @@ int test_map_kptr_ref3(struct __sk_buff *ctx) return 0; } +int num_of_refs; + +SEC("syscall") +int count_ref(void *ctx) +{ + struct prog_test_ref_kfunc *p; + unsigned long arg = 0; + + p = bpf_kfunc_call_test_acquire(&arg); + if (!p) + return 1; + + num_of_refs = p->cnt.refs.counter; + + bpf_kfunc_call_test_release(p); + return 0; +} + SEC("syscall") int test_ls_map_kptr_ref1(void *ctx) {