Hi,
On 12/11/2023 8:56 PM, Jiri Olsa wrote:
> On Mon, Dec 11, 2023 at 07:28:43PM +0800, Hou Tao wrote:
>> From: Hou Tao <houtao1@xxxxxxxxxx>
>>
>> If an abnormally huge cnt is used for multi-uprobes attachment, the
>> following warning will be reported:
>>
>> ------------[ cut here ]------------
>> WARNING: CPU: 7 PID: 406 at mm/util.c:632 kvmalloc_node+0xd9/0xe0
>> Modules linked in: bpf_testmod(O)
>> CPU: 7 PID: 406 Comm: test_progs Tainted: G ...... 6.7.0-rc3+ #32
>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) ......
>> RIP: 0010:kvmalloc_node+0xd9/0xe0
>> ......
>> Call Trace:
>> <TASK>
>> ? __warn+0x89/0x150
>> ? kvmalloc_node+0xd9/0xe0
>> bpf_uprobe_multi_link_attach+0x14a/0x480
>> __sys_bpf+0x14a9/0x2bc0
>> do_syscall_64+0x36/0xb0
>> entry_SYSCALL_64_after_hwframe+0x6e/0x76
>> ......
>> </TASK>
>> ---[ end trace 0000000000000000 ]---
>>
>> So add a test to ensure the warning is fixed.
>>
>> Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
>> ---
>> .../bpf/prog_tests/uprobe_multi_test.c | 43 ++++++++++++++++++-
>> 1 file changed, 42 insertions(+), 1 deletion(-)
>>
>> diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
>> index ece260cf2c0b..379ee9cc6221 100644
>> --- a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
>> +++ b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
>> @@ -234,6 +234,45 @@ static void test_attach_api_syms(void)
>> test_attach_api("/proc/self/exe", NULL, &opts);
>> }
>>
>> +static void test_failed_link_api(void)
>> +{
>> + LIBBPF_OPTS(bpf_link_create_opts, opts);
>> + const char *path = "/proc/self/exe";
>> + struct uprobe_multi *skel = NULL;
>> + unsigned long *offsets = NULL;
>> + const char *syms[3] = {
>> + "uprobe_multi_func_1",
>> + "uprobe_multi_func_2",
>> + "uprobe_multi_func_3",
>> + };
>> + int link_fd = -1, err;
>> +
>> + err = elf_resolve_syms_offsets(path, 3, syms, (unsigned long **) &offsets, STT_FUNC);
>> + if (!ASSERT_OK(err, "elf_resolve_syms_offsets"))
>> + return;
> we should not need any symbols/offset for this tests right?
>
> the allocation takes place before the offsets are checked,
> so I think using just some pointer != NULL should be enough?
Yes. Will update.
>
> thanks,
> jirka
>
>> +
>> + skel = uprobe_multi__open_and_load();
>> + if (!ASSERT_OK_PTR(skel, "uprobe_multi__open_and_load"))
>> + goto cleanup;
>> +
>> + /* abnormal cnt */
>> + opts.uprobe_multi.path = path;
>> + opts.uprobe_multi.offsets = offsets;
>> + opts.uprobe_multi.cnt = INT_MAX;
>> + opts.kprobe_multi.flags = 0;
>> + link_fd = bpf_link_create(bpf_program__fd(skel->progs.uprobe), 0,
>> + BPF_TRACE_UPROBE_MULTI, &opts);
>> + if (!ASSERT_ERR(link_fd, "link_fd"))
>> + goto cleanup;
>> + if (!ASSERT_EQ(link_fd, -ENOMEM, "no mem fail"))
>> + goto cleanup;
>> +cleanup:
>> + if (link_fd >= 0)
>> + close(link_fd);
>> + uprobe_multi__destroy(skel);
>> + free(offsets);
>> +}
>> +
>> static void __test_link_api(struct child *child)
>> {
>> int prog_fd, link1_fd = -1, link2_fd = -1, link3_fd = -1, link4_fd = -1;
>> @@ -311,7 +350,7 @@ static void __test_link_api(struct child *child)
>> free(offsets);
>> }
>>
>> -void test_link_api(void)
>> +static void test_link_api(void)
>> {
>> struct child *child;
>>
>> @@ -408,6 +447,8 @@ void test_uprobe_multi_test(void)
>> test_attach_api_syms();
>> if (test__start_subtest("link_api"))
>> test_link_api();
>> + if (test__start_subtest("failed_link_api"))
>> + test_failed_link_api();
>> if (test__start_subtest("bench_uprobe"))
>> test_bench_attach_uprobe();
>> if (test__start_subtest("bench_usdt"))
>> --
>> 2.29.2
>>
