Re: [RFC][PATCH] tracing: Have stack tracer force RCU to be watching

From	Steven Rostedt <rostedt@goodmis.org>
Newsgroups	linux.kernel
Subject	Re: [RFC][PATCH] tracing: Have stack tracer force RCU to be watching
Date	2015-10-21 13:40 +0200
Message-ID	<qlZUl-1FU-13@gated-at.bofh.it> (permalink)
References	<qlHNL-qO-1@gated-at.bofh.it> <qlLHH-65j-13@gated-at.bofh.it> <qlMNs-7E9-41@gated-at.bofh.it> <qlWD7-5sb-9@gated-at.bofh.it>
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On Wed, 21 Oct 2015 10:01:42 +0200
Peter Zijlstra <peterz@infradead.org> wrote:

> > I should probably add a "if (in_nmi()) return" somewhere.
> 
> But if there's an arch that doesn't use a separate NMI stack, the NMI
> might cause the largest stack, which would then remain invisible from
> the stack-tracer.
> 
> Should we not instead fix the NMI-safety of this tracer?

We could, but that should be a separate project, as that would require
doing everything lockless, which would require a redesign. Is that
worth it?

For now, the safe thing to do is the if (in_nmi()), but certainly, if
someone gets time to make it NMI safe, we can do that too.

-- Steve
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Thread

[RFC][PATCH] tracing: Have stack tracer force RCU to be watching Steven Rostedt <rostedt@goodmis.org> - 2015-10-20 18:20 +0200
  Re: [RFC][PATCH] tracing: Have stack tracer force RCU to be watching "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-20 22:30 +0200
    Re: [RFC][PATCH] tracing: Have stack tracer force RCU to be  watching Steven Rostedt <rostedt@goodmis.org> - 2015-10-20 23:40 +0200
      Re: [RFC][PATCH] tracing: Have stack tracer force RCU to be watching "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> - 2015-10-21 01:50 +0200
        Re: [RFC][PATCH] tracing: Have stack tracer force RCU to be  watching Steven Rostedt <rostedt@goodmis.org> - 2015-10-21 02:00 +0200
          Re: [RFC][PATCH] tracing: Have stack tracer force RCU to be  watching Steven Rostedt <rostedt@goodmis.org> - 2015-10-21 19:50 +0200
      Re: [RFC][PATCH] tracing: Have stack tracer force RCU to be watching Peter Zijlstra <peterz@infradead.org> - 2015-10-21 10:10 +0200
        Re: [RFC][PATCH] tracing: Have stack tracer force RCU to be  watching Steven Rostedt <rostedt@goodmis.org> - 2015-10-21 13:40 +0200
          Re: [RFC][PATCH] tracing: Have stack tracer force RCU to be watching Peter Zijlstra <peterz@infradead.org> - 2015-10-21 14:00 +0200

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