On 2026/7/11 06:15, Jiri Olsa wrote:
> On Fri, Jul 10, 2026 at 10:47:33PM +0800, Leon Hwang wrote:
>> Since tracing_multi link does not set ftrace_managed, it would fail to
>> release the tracing_multi link when attaching tracing_multi link and
>> then attaching fentry link.
>>
>> [ 3.714215] WARNING: kernel/bpf/trampoline.c:1727 at
>> bpf_trampoline_multi_detach+0x20b/0x240, CPU#1: test_progs/97
>> ...
>> [ 3.733170] bpf_tracing_multi_link_release+0x14/0x30
>> [ 3.733890] bpf_link_free+0x58/0x130
>> [ 3.734414] bpf_link_release+0x23/0x30
>>
>> Fix it by setting 'ftrace_managed = true' in register_fentry_multi().
>>
>> Fixes: aef4dfa790b2 ("bpf: Add bpf_trampoline_multi_attach/detach functions")
>> Signed-off-by: Leon Hwang <[email protected]>
>> ---
>> kernel/bpf/trampoline.c | 1 +
>> 1 file changed, 1 insertion(+)
>>
>> diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c
>> index 1a721fc4bef5..6eadf64f7ec9 100644
>> --- a/kernel/bpf/trampoline.c
>> +++ b/kernel/bpf/trampoline.c
>> @@ -1536,6 +1536,7 @@ static int register_fentry_multi(struct bpf_trampoline
>> *tr, struct bpf_tramp_ima
>> if (bpf_trampoline_use_jmp(tr->flags))
>> addr = ftrace_jmp_set(addr);
>>
>> + tr->func.ftrace_managed = true;
>
> I wonder we could set tr->func.ftrace_managed early in bpf_trampoline_get,
> but we could do that as follow up
Makes sense. Let me try it when adding tracing_multi link support for
bpf progs.
>
> Acked-by: Jiri Olsa <[email protected]>
Thanks for your review.
Leon
>
> thanks,
> jirka
>
>
>> ftrace_hash_add(data->reg, data->entry, ip, addr);
>> tr->cur_image = im;
>> return 0;
>> --
>> 2.55.0
>>
