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From:   Andy Lutomirski <luto@kernel.org>
Date:   Mon, 25 Jun 2018 16:30:39 -0700
Message-ID: <CALCETrX3KOOhNP14CcZ60W9ys3F6hC+oH2xyF9a2OPOO_Lqv3Q@mail.gmail.com>
Subject: Re: [RFC 2/2] rcu: Remove ->dynticks_nmi_nesting from struct rcu_dynticks
To:     Steven Rostedt <rostedt@goodmis.org>
Cc:     Andrew Lutomirski <luto@kernel.org>,
        "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
        joel@joelfernandes.org, Byungchul Park <byungchul.park@lge.com>,
        byungchul park <max.byungchul.park@gmail.com>,
        Lai Jiangshan <jiangshanlai@gmail.com>,
        Josh Triplett <josh@joshtriplett.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        LKML <linux-kernel@vger.kernel.org>, kernel-team@lge.com
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On Mon, Jun 25, 2018 at 3:16 PM Steven Rostedt <rostedt@goodmis.org> wrote:
>
> On Mon, 25 Jun 2018 13:47:45 -0700
> Andy Lutomirski <luto@kernel.org> wrote:
>
> >
> > As a straightforward example, NMI and MCE can nest inside each other.
>
> But I'm not sure how stable the machine becomes when MCE's start
> interrupting NMIs. Also, can MCE callbacks use RCU?
>
> > IIRC we treat #DB somewhat NMI-ish-ly as well.
>
> And #DB is something I think we finally said shouldn't be done in NMIs,
> IIRC.
>

No one ever applied the patch to make it so, so we still support it.