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Subject[PATCH RT 05/23] sched: migrate dis/enable: Use sleeping lock…() to annotate sleeping poin ts
Date
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
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