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;
From:   zanussi@kernel.org
To:     LKML <linux-kernel@vger.kernel.org>,
        linux-rt-users <linux-rt-users@vger.kernel.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Carsten Emde <C.Emde@osadl.org>,
        John Kacur <jkacur@redhat.com>,
        Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
        Daniel Wagner <wagi@monom.org>,
        Tom Zanussi <zanussi@kernel.org>
Subject: [PATCH RT 05/23] =?UTF-8?q?sched:=20migrate=5Fdis/enable:=20Use?= =?UTF-8?q?=20sleeping=5Flock=E2=80=A6()=20to=20annotate=20sleeping=20poin?= =?UTF-8?q?ts?=
Date:   Thu, 27 Feb 2020 08:33:16 -0600
Message-Id: <0078d43bf3e62b36f0890731c2f6fd277a93927b.1582814004.git.zanussi@kernel.org>
In-Reply-To: <cover.1582814004.git.zanussi@kernel.org>
References: <cover.1582814004.git.zanussi@kernel.org>
In-Reply-To: <cover.1582814004.git.zanussi@kernel.org>
References: <cover.1582814004.git.zanussi@kernel.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

From: Scott Wood <swood@redhat.com>

v4.14.170-rt75-rc2 stable review patch.
If anyone has any objections, please let me know.

-----------


[ Upstream commit 4230dd3824c3e1785504e6f757ce79a4b55651fa ]

Without this, rcu_note_context_switch() will complain if an RCU read lock
is held when migrate_enable() calls stop_one_cpu().  Likewise when
migrate_disable() calls pin_current_cpu() which calls __read_rt_lock() --
which bypasses the part of the mutex code that calls sleeping_lock_inc().

Signed-off-by: Scott Wood <swood@redhat.com>
[bigeasy: use sleeping_lock_…() ]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Tom Zanussi <zanussi@kernel.org>

 Conflicts:
	kernel/sched/core.c
---
 kernel/cpu.c        | 2 ++
 kernel/sched/core.c | 3 +++
 2 files changed, 5 insertions(+)

diff --git a/kernel/cpu.c b/kernel/cpu.c
index 05b93cfa6fd9..9be794896d87 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -314,7 +314,9 @@ void pin_current_cpu(void)
 	preempt_lazy_enable();
 	preempt_enable();
 
+	sleeping_lock_inc();
 	__read_rt_lock(cpuhp_pin);
+	sleeping_lock_dec();
 
 	preempt_disable();
 	preempt_lazy_disable();
diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index fde47216af94..fcff75934bdc 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7045,7 +7045,10 @@ void migrate_enable(void)
 			unpin_current_cpu();
 			preempt_lazy_enable();
 			preempt_enable();
+
+			sleeping_lock_inc();
 			stop_one_cpu(task_cpu(p), migration_cpu_stop, &arg);
+			sleeping_lock_dec();
 			tlb_migrate_finish(p->mm);
 
 			return;
-- 
2.14.1