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?
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
>
