Re: [PATCH v2] tracing/uprobe: Add missing PID filter for uretprobe

Jiri Olsa
2024-08-29T23:22:10Z

On Thu, Aug 29, 2024 at 11:12:41PM +0200, Oleg Nesterov wrote:
> Ah. we certainly misunderstand each other.
>
> On 08/29, Jiri Olsa wrote:
> >
> > On Thu, Aug 29, 2024 at 05:20:33PM +0200, Oleg Nesterov wrote:
> >
> > SNIP
>
> SNIP
>
> > right.. if the event is not added by perf_trace_add on this cpu
> > it won't go pass this point, so no problem for perf
>
> Yes, and this is what I tried to verify. In your previous email you said
>
> and I think the same will happen for perf record in this case where instead of
> running the program we will execute perf_tp_event
>
> and I tried verify this can't happen. So no problem for perf ;)

yea, I was wrong, you should be used to it by now ;-)

>
> > but the issue is with bpf program triggered earlier by return uprobe
>
> Well, the issue with bpf program (with the bpf_prog_array_valid(call) code
> in __uprobe_perf_func) was clear from the very beginning, no questions.
>
> > and [1] patch seems to fix that
>
> I'd say this patch fixes the symptoms, and it doesn't fix all the problems.
> But I can't suggest anything better for bpf code, so I won't really argue.
> However the changelog and even the subject is wrong.
>
> > I sent out the bpf selftest that triggers the issue [2]
>
> Thanks, I'll try take a look tomorrow.

thanks,
jirka