From: Joel Fernandes <joel@joelfernandes.org>
To: Scott Wood <swood@redhat.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
linux-rt-users@vger.kernel.org, linux-kernel@vger.kernel.org,
"Paul E . McKenney" <paulmck@linux.ibm.com>,
Thomas Gleixner <tglx@linutronix.de>,
Peter Zijlstra <peterz@infradead.org>,
Juri Lelli <juri.lelli@redhat.com>,
Clark Williams <williams@redhat.com>
Subject: Re: [PATCH RT v2 3/3] rcu: Disable use_softirq on PREEMPT_RT
Date: Thu, 22 Aug 2019 20:52:18 -0400 [thread overview]
Message-ID: <20190823005218.GA36261@google.com> (raw)
In-Reply-To: <c44d6ab34f2f4e4a5d36036cc8b356a3f4f3519b.camel@redhat.com>
On Thu, Aug 22, 2019 at 02:31:17PM -0500, Scott Wood wrote:
> On Thu, 2019-08-22 at 09:59 -0400, Joel Fernandes wrote:
> > On Wed, Aug 21, 2019 at 06:19:06PM -0500, Scott Wood wrote:
> > > I think the prohibition on use_softirq can be dropped once RT gets the
> > > latest RCU code, but the question of what use_softirq should default
> > > to on PREEMPT_RT remains.
> >
> > Independent of the question of what use_softirq should default to, could
> > we
> > test RT with latest RCU code now to check if the deadlock goes away? That
> > way, maybe we can find any issues in current RCU that cause scheduler
> > deadlocks in the situation you pointed. The reason I am asking is because
> > recently additional commits [1] try to prevent deadlock and it'd be nice
> > to
> > ensure that other conditions are not lingering (I don't think they are but
> > it'd be nice to be sure).
> >
> > I am happy to do such testing myself if you want, however what does it
> > take
> > to apply the RT patchset to the latest mainline? Is it an achievable feat?
>
> I did run such a test (cherry picking all RCU patches that aren't already in
> RT, plus your RFC patch to rcu_read_unlock_special, rather than applying RT
> to current mainline) with rcutorture plus a looping kernel build overnight,
> and didn't see any splats with or without use_softirq.
Cool, that's good to know you didn't see splats!
thanks,
- Joel
prev parent reply other threads:[~2019-08-23 0:52 UTC|newest]
Thread overview: 43+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-21 23:19 [PATCH RT v2 0/3] RCU fixes Scott Wood
2019-08-21 23:19 ` [PATCH RT v2 1/3] rcu: Acquire RCU lock when disabling BHs Scott Wood
2019-08-21 23:33 ` Paul E. McKenney
2019-08-22 13:39 ` Joel Fernandes
2019-08-22 15:27 ` Paul E. McKenney
2019-08-23 1:50 ` Joel Fernandes
2019-08-23 2:11 ` Paul E. McKenney
2019-08-23 3:23 ` Scott Wood
2019-08-23 12:30 ` Paul E. McKenney
2019-08-23 16:17 ` Sebastian Andrzej Siewior
2019-08-23 19:46 ` Scott Wood
2019-08-26 15:59 ` Sebastian Andrzej Siewior
2019-08-26 23:21 ` Scott Wood
2019-08-23 2:36 ` Scott Wood
2019-08-23 2:54 ` Paul E. McKenney
2019-08-21 23:19 ` [PATCH RT v2 2/3] sched: migrate_enable: Use sleeping_lock to indicate involuntary sleep Scott Wood
2019-08-21 23:35 ` Paul E. McKenney
2019-08-23 1:21 ` Scott Wood
2019-08-23 16:20 ` Sebastian Andrzej Siewior
2019-08-23 19:28 ` Scott Wood
2019-08-24 3:10 ` Joel Fernandes
2019-08-26 15:25 ` Sebastian Andrzej Siewior
2019-08-26 16:29 ` Paul E. McKenney
2019-08-26 17:49 ` Scott Wood
2019-08-26 18:12 ` Paul E. McKenney
2019-08-27 9:23 ` Sebastian Andrzej Siewior
2019-08-27 13:08 ` Joel Fernandes
2019-08-27 15:58 ` Paul E. McKenney
2019-08-27 16:06 ` Joel Fernandes
2019-08-27 15:53 ` Paul E. McKenney
2019-08-28 9:27 ` Sebastian Andrzej Siewior
2019-08-28 12:54 ` Paul E. McKenney
2019-08-28 13:14 ` Sebastian Andrzej Siewior
2019-08-28 13:59 ` Joel Fernandes
2019-08-28 15:51 ` Paul E. McKenney
2019-08-28 15:50 ` Paul E. McKenney
2019-08-21 23:19 ` [PATCH RT v2 3/3] rcu: Disable use_softirq on PREEMPT_RT Scott Wood
2019-08-21 23:40 ` Paul E. McKenney
2019-08-23 16:32 ` Sebastian Andrzej Siewior
2019-08-22 13:59 ` Joel Fernandes
2019-08-22 15:29 ` Paul E. McKenney
2019-08-22 19:31 ` Scott Wood
2019-08-23 0:52 ` Joel Fernandes [this message]
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