From a29cf3268ccd160936a6435ece3cdcefc022e8b6 Mon Sep 17 00:00:00 2001
From: Scott Wood <swood@redhat.com>
Date: Tue, 24 Sep 2019 14:36:41 +0200
Subject: [PATCH 472/518] =?UTF-8?q?sched:=20migrate=5Fdis/enable:=20Use=20?=
 =?UTF-8?q?sleeping=5Flock=E2=80=A6()=20to=20annotate=20sleeping=20points?=
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[ 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 f4f25751460e6..856ec89899605 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -316,7 +316,9 @@ 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 e81d24de721bf..6e60038237e80 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7047,7 +7047,10 @@ 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;
-- 
2.41.0

