Re: [PATCH v1 4/8] tracing/bpf: guard syscall probe with preempt_notrace

[Alexei Starovoitov]

On Thu, Oct 3, 2024 at 3:25 PM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> On Thu,  3 Oct 2024 11:16:34 -0400
> Mathieu Desnoyers <mathieu.desnoyers@xxxxxxxxxxxx> wrote:
>
> > In preparation for allowing system call enter/exit instrumentation to
> > handle page faults, make sure that bpf can handle this change by
> > explicitly disabling preemption within the bpf system call tracepoint
> > probes to respect the current expectations within bpf tracing code.
> >
> > This change does not yet allow bpf to take page faults per se within its
> > probe, but allows its existing probes to adapt to the upcoming change.
> >
>
> I guess the BPF folks should state if this is needed or not?
>
> Does the BPF hooks into the tracepoints expect preemption to be disabled
> when called?

Andrii pointed it out already.
bpf doesn't need preemption to be disabled.
Only migration needs to be disabled.