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From: Scott Wood <swood@redhat.com>
Date: Tue, 24 Sep 2019 14:36:41 +0200
Subject: [PATCH 297/351] =?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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Origin: https://git.kernel.org/cgit/linux/kernel/git/rt/linux-stable-rt.git/commit?id=302ef1699867ae23b2531b0f689517b615c25866
[ 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>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
[bigeasy: use sleeping_lock_…() ]
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
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 396394ebbc5b..4bf82665f28c 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -310,7 +310,9 @@ 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 ea275b4b3d0a..b5675306ebed 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -7367,7 +7367,10 @@ 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;
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