linux-kernel - Re: [PATCH 0/8] tracing vs rcu vs nmi

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Date:   Wed, 12 Feb 2020 11:09:40 +0100
From:   Peter Zijlstra <peterz@...radead.org>
To:     linux-kernel@...r.kernel.org, linux-arch@...r.kernel.org,
        rostedt@...dmis.org, linux@...linux.org.uk
Cc:     mingo@...nel.org, joel@...lfernandes.org,
        gregkh@...uxfoundation.org, gustavo@...eddedor.com,
        tglx@...utronix.de, paulmck@...nel.org, josh@...htriplett.org,
        mathieu.desnoyers@...icios.com, jiangshanlai@...il.com
Subject: Re: [PATCH 0/8] tracing vs rcu vs nmi

On Wed, Feb 12, 2020 at 10:32:10AM +0100, Peter Zijlstra wrote:
> Hi all,
> 
> These here patches are the result of Mathieu and Steve trying to get commit
> 865e63b04e9b2 ("tracing: Add back in rcu_irq_enter/exit_irqson() for rcuidle
> tracepoints") reverted again.
> 
> One of the things discovered is that tracing MUST NOT happen before nmi_enter()
> or after nmi_exit(). I've only fixed x86, but quickly gone through other
> architectures and there is definitely more stuff to be fixed (simply grep for
> nmi_enter in your arch).

Someone should probably look at the whole ARM FiQ stuff, I got a little
lost, but probably handle_fiq_as_nmi() wants notrace and everything
using set_fiq_handler() wants looking at.