Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Tue, 21 Nov 2017 09:14:25 -0600
From:   Clark Williams <williams@redhat.com>
To:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc:     Steven Rostedt <rostedt@goodmis.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@kernel.org>,
        Daniel Bristot de Oliveira <bristot@redhat.com>,
        John Kacur <jkacur@redhat.com>, Scott Wood <swood@redhat.com>,
        Mike Galbraith <efault@gmx.de>
Subject: [PATCH RT] fix IPI balancing for 4.14-rt
Message-ID: <20171121091425.7577dc02@tagon>
In-Reply-To: <20171006140504.48dc32c1@gandalf.local.home>
References: <20171006140504.48dc32c1@gandalf.local.home>
Organization: Red Hat, Inc
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha512;
 boundary="Sig_/IEqgoZ_=FzGcLi9oBtCOfZf"; protocol="application/pgp-signature"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

--Sig_/IEqgoZ_=FzGcLi9oBtCOfZf
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: quoted-printable

=46rom 8ea8311b75a40bdea03e7f8228a0578b6367e9d1 Mon Sep 17 00:00:00 2001
From: Clark Williams <williams@redhat.com>
Date: Mon, 20 Nov 2017 14:26:12 -0600
Subject: [PATCH] [rt] sched/rt: fix panic in double_lock_balance with
 simplified IPI RT balancing

I was testing 4.14-rt1 on a large system (cores =3D=3D 96) and saw that
we were getting into an rt balancing storm, so I tried applying Steven's
patch (not upstream yet):

    sched/rt: Simplify the IPI rt balancing logic

Booting the resulting kernel yielded a panic in
double_lock_balance() due to irqs not being disabled.

This patch changes the calls to raw_spin_{lock,unlock} in the
function rto_push_irq_work_function, to be raw_spin_{lock,unlock}_irq.
Not sure if that's too heavy a hammer, but the resulting kernel boots
and runs and survives 12h runs of rteval. Once Steven's patch goes in=20
upstream, we'll need something like this in RT.

Signed-off-by: Clark Williams <williams@redhat.com>
---
 kernel/sched/rt.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 57fb251dd8ce..a5cd0cea2f0f 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -2008,9 +2008,9 @@ void rto_push_irq_work_func(struct irq_work *work)
 	 * When it gets updated, a check is made if a push is possible.
 	 */
 	if (has_pushable_tasks(rq)) {
-		raw_spin_lock(&rq->lock);
+		raw_spin_lock_irq(&rq->lock);
 		push_rt_tasks(rq);
-		raw_spin_unlock(&rq->lock);
+		raw_spin_unlock_irq(&rq->lock);
 	}
=20
 	raw_spin_lock(&rq->rd->rto_lock);
--=20
2.14.3


--=20
The United States Coast Guard
Ruining Natural Selection since 1790

--Sig_/IEqgoZ_=FzGcLi9oBtCOfZf
Content-Type: application/pgp-signature
Content-Description: OpenPGP digital signature

-----BEGIN PGP SIGNATURE-----
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=SvVM
-----END PGP SIGNATURE-----

--Sig_/IEqgoZ_=FzGcLi9oBtCOfZf--

From 1587139501809710173@xxx Mon Dec 18 16:22:59 +0000 2017
X-GM-THRID: 1585337530187630540
X-Gmail-Labels: Inbox,Category Forums