[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <13761fee4b71cc004ad0d6709875ce917ff28fce.camel@redhat.com>
Date: Thu, 27 Jun 2019 15:17:27 -0500
From: Scott Wood <swood@...hat.com>
To: paulmck@...ux.ibm.com, Joel Fernandes <joel@...lfernandes.org>
Cc: Steven Rostedt <rostedt@...dmis.org>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
rcu <rcu@...r.kernel.org>, LKML <linux-kernel@...r.kernel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
Peter Zijlstra <peterz@...radead.org>,
Josh Triplett <josh@...htriplett.org>,
Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
Lai Jiangshan <jiangshanlai@...il.com>
Subject: Re: [RFC] Deadlock via recursive wakeup via RCU with threadirqs
On Thu, 2019-06-27 at 11:41 -0700, Paul E. McKenney wrote:
> On Thu, Jun 27, 2019 at 02:16:38PM -0400, Joel Fernandes wrote:
> >
> > I think the fix should be to prevent the wake-up not based on whether we
> > are
> > in hard/soft-interrupt mode but that we are doing the rcu_read_unlock()
> > from
> > a scheduler path (if we can detect that)
>
> Or just don't do the wakeup at all, if it comes to that. I don't know
> of any way to determine whether rcu_read_unlock() is being called from
> the scheduler, but it has been some time since I asked Peter Zijlstra
> about that.
>
> Of course, unconditionally refusing to do the wakeup might not be happy
> thing for NO_HZ_FULL kernels that don't implement IRQ work.
Couldn't smp_send_reschedule() be used instead?
-Scott
Powered by blists - more mailing lists