Re: [PATCH] ftrace: Disable preemption in the tracepoint callbacks handling filtered pids

[Google]

On Tue, 3 Mar 2026 09:39:49 -0500
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> On Tue, 3 Mar 2026 13:17:06 +0900
> Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx> wrote:
> 
> > diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c
> > index 9928da636c9d..3b3aaf4831e9 100644
> > --- a/kernel/trace/trace_events.c
> > +++ b/kernel/trace/trace_events.c
> > @@ -1039,6 +1039,7 @@ event_filter_pid_sched_process_exit(void *data, struct task_struct *task)
> >  	struct trace_pid_list *pid_list;
> >  	struct trace_array *tr = data;
> >  
> > +	guard(preempt)();
> >  	pid_list = rcu_dereference_raw(tr->filtered_pids);
> >  	trace_filter_add_remove_task(pid_list, NULL, task);
> >  
> > @@ -1054,6 +1055,7 @@ event_filter_pid_sched_process_fork(void *data,
> >  	struct trace_pid_list *pid_list;
> >  	struct trace_array *tr = data;
> >  
> > +	guard(preempt)();
> >  	pid_list = rcu_dereference_sched(tr->filtered_pids);
> >  	trace_filter_add_remove_task(pid_list, self, task);
> >  
> 
> Yep. I can make them two different patches. Do you want me to take this as
> your patch? I'll need a SoB from you then.

I think we can combine those since it fixes the same commit.
(just for bisectability)

Signed-off-by: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>

Thank you,

> 
> -- Steve


-- 
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>