From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Joel Fernandes <joel@joelfernandes.org>,
Byungchul Park <max.byungchul.park@gmail.com>,
Byungchul Park <byungchul.park@lge.com>,
jiangshanlai@gmail.com, josh@joshtriplett.org,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
linux-kernel@vger.kernel.org, kernel-team@lge.com,
luto@kernel.org
Subject: Re: [RFC 2/2] rcu: Remove ->dynticks_nmi_nesting from struct rcu_dynticks
Date: Fri, 22 Jun 2018 13:58:59 -0700 [thread overview]
Message-ID: <20180622205859.GW3593@linux.vnet.ibm.com> (raw)
In-Reply-To: <20180622143247.781028b1@gandalf.local.home>
On Fri, Jun 22, 2018 at 02:32:47PM -0400, Steven Rostedt wrote:
> On Fri, 22 Jun 2018 11:19:16 -0700
> Joel Fernandes <joel@joelfernandes.org> wrote:
>
> > Sure. So in a later thread you mentioned "usermode helpers". I took a closer
> > look at that subsystem, and it seems you can execute usermode helpers from
> > atomic sections with help of UMH_NO_WAIT flag.
> >
> > Then I checked where this flag is used and it turns out its from the
> > mce_work_trigger function in x86/kernel/cpu/mcheck/dev-mcelog.c which can be
> > called infact from an interrupt context (mce_notify_irq).
> >
> > Is this the usecase you remember causing this weird transitions to userspace?
>
> But this case still looks like it uses work queues, it just doesn't
> wait for the result.
>
> I'll have to look at the code from what it looked like back in 2011, to
> see if there was an actual issue here back then.
There was. Been there, got the failure on real hardware. ;-)
Thanx, Paul
next prev parent reply other threads:[~2018-06-22 20:57 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-20 8:47 [RFC 1/2] rcu: Do prepare and cleanup idle depending on in_nmi() Byungchul Park
2018-06-20 8:47 ` [RFC 2/2] rcu: Remove ->dynticks_nmi_nesting from struct rcu_dynticks Byungchul Park
2018-06-20 14:58 ` Paul E. McKenney
2018-06-20 16:05 ` Byungchul Park
2018-06-20 16:49 ` Paul E. McKenney
2018-06-20 17:15 ` Byungchul Park
2018-06-20 17:40 ` Paul E. McKenney
2018-06-21 6:39 ` Byungchul Park
2018-06-21 6:48 ` Byungchul Park
2018-06-21 10:08 ` Byungchul Park
2018-06-21 15:05 ` Paul E. McKenney
2018-06-21 15:04 ` Paul E. McKenney
2018-06-22 3:00 ` Byungchul Park
2018-06-22 13:36 ` Paul E. McKenney
2018-06-22 5:56 ` Joel Fernandes
2018-06-22 13:28 ` Paul E. McKenney
2018-06-22 14:19 ` Andy Lutomirski
2018-06-22 16:12 ` Paul E. McKenney
2018-06-22 16:01 ` Steven Rostedt
2018-06-22 18:14 ` Paul E. McKenney
2018-06-22 18:19 ` Joel Fernandes
2018-06-22 18:32 ` Steven Rostedt
2018-06-22 20:05 ` Joel Fernandes
2018-06-25 8:28 ` Byungchul Park
2018-06-25 16:39 ` Joel Fernandes
2018-06-25 17:19 ` Paul E. McKenney
2018-06-25 19:15 ` Joel Fernandes
2018-06-25 20:25 ` Steven Rostedt
2018-06-25 20:47 ` Paul E. McKenney
2018-06-25 20:47 ` Andy Lutomirski
2018-06-25 22:16 ` Steven Rostedt
2018-06-25 23:30 ` Andy Lutomirski
2018-06-25 22:15 ` Steven Rostedt
2018-06-25 23:32 ` Andy Lutomirski
2018-06-25 21:25 ` Joel Fernandes
2018-06-22 20:58 ` Paul E. McKenney [this message]
2018-06-22 20:58 ` Paul E. McKenney
2018-06-22 21:00 ` Steven Rostedt
2018-06-22 21:16 ` Paul E. McKenney
2018-06-22 22:03 ` Andy Lutomirski
2018-06-23 17:53 ` Paul E. McKenney
2018-06-28 20:02 ` Paul E. McKenney
2018-06-28 21:13 ` Joel Fernandes
2018-06-28 21:41 ` Paul E. McKenney
2018-06-23 15:48 ` Joel Fernandes
2018-06-23 17:56 ` Paul E. McKenney
2018-06-24 3:02 ` Joel Fernandes
2018-06-20 13:33 ` [RFC 1/2] rcu: Do prepare and cleanup idle depending on in_nmi() Steven Rostedt
2018-06-20 14:58 ` Paul E. McKenney
2018-06-20 15:25 ` Byungchul Park
2018-06-20 14:50 ` Paul E. McKenney
2018-06-20 15:43 ` Steven Rostedt
2018-06-20 15:56 ` Paul E. McKenney
2018-06-20 16:11 ` Byungchul Park
2018-06-20 16:14 ` Steven Rostedt
2018-06-20 16:37 ` Byungchul Park
2018-06-20 16:11 ` Steven Rostedt
2018-06-20 16:30 ` Paul E. McKenney
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