Fix rhbzs 789641 and 789644

Fix RCU usage during cpu idle (rhbz 789641)
Fix mce rcu splat (rhbz 789644)

1 files changed, 118 insertions, 0 deletions

diff --git a/x86-Avoid-invoking-RCU-when-CPU-is-idle.patch b/x86-Avoid-invoking-RCU-when-CPU-is-idle.patch
new file mode 100644
index 000000000..2d45056bb
--- /dev/null
+++ b/x86-Avoid-invoking-RCU-when-CPU-is-idle.patch
@@ -0,0 +1,118 @@
+diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
+index 15763af..f6978b0 100644
+--- a/arch/x86/kernel/process.c
++++ b/arch/x86/kernel/process.c
+@@ -386,17 +386,21 @@ void default_idle(void)
+ 		 */
+ 		smp_mb();
+ 
++		rcu_idle_enter();
+ 		if (!need_resched())
+ 			safe_halt();	/* enables interrupts racelessly */
+ 		else
+ 			local_irq_enable();
++		rcu_idle_exit();
+ 		current_thread_info()->status |= TS_POLLING;
+ 		trace_power_end(smp_processor_id());
+ 		trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
+ 	} else {
+ 		local_irq_enable();
+ 		/* loop is done by the caller */
++		rcu_idle_enter();
+ 		cpu_relax();
++		rcu_idle_exit();
+ 	}
+ }
+ #ifdef CONFIG_APM_MODULE
+@@ -457,14 +461,19 @@ static void mwait_idle(void)
+ 
+ 		__monitor((void *)&current_thread_info()->flags, 0, 0);
+ 		smp_mb();
++		rcu_idle_enter();
+ 		if (!need_resched())
+ 			__sti_mwait(0, 0);
+ 		else
+ 			local_irq_enable();
++		rcu_idle_exit();
+ 		trace_power_end(smp_processor_id());
+ 		trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
+-	} else
++	} else {
+ 		local_irq_enable();
++		rcu_idle_enter();
++		rcu_idle_exit();
++	}
+ }
+ 
+ /*
+@@ -477,8 +486,10 @@ static void poll_idle(void)
+ 	trace_power_start(POWER_CSTATE, 0, smp_processor_id());
+ 	trace_cpu_idle(0, smp_processor_id());
+ 	local_irq_enable();
++	rcu_idle_enter();
+ 	while (!need_resched())
+ 		cpu_relax();
++	rcu_idle_exit();
+ 	trace_power_end(smp_processor_id());
+ 	trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
+ }
+diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
+index 485204f..6d9d4d5 100644
+--- a/arch/x86/kernel/process_32.c
++++ b/arch/x86/kernel/process_32.c
+@@ -100,7 +100,6 @@ void cpu_idle(void)
+ 	/* endless idle loop with no priority at all */
+ 	while (1) {
+ 		tick_nohz_idle_enter();
+-		rcu_idle_enter();
+ 		while (!need_resched()) {
+ 
+ 			check_pgt_cache();
+@@ -117,7 +116,6 @@ void cpu_idle(void)
+ 				pm_idle();
+ 			start_critical_timings();
+ 		}
+-		rcu_idle_exit();
+ 		tick_nohz_idle_exit();
+ 		preempt_enable_no_resched();
+ 		schedule();
+diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
+index 9b9fe4a..55a1a35 100644
+--- a/arch/x86/kernel/process_64.c
++++ b/arch/x86/kernel/process_64.c
+@@ -140,13 +140,9 @@ void cpu_idle(void)
+ 			/* Don't trace irqs off for idle */
+ 			stop_critical_timings();
+ 
+-			/* enter_idle() needs rcu for notifiers */
+-			rcu_idle_enter();
+-
+ 			if (cpuidle_idle_call())
+ 				pm_idle();
+ 
+-			rcu_idle_exit();
+ 			start_critical_timings();
+ 
+ 			/* In many cases the interrupt that ended idle
+diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
+index 20bce51..a9ddab8 100644
+--- a/drivers/idle/intel_idle.c
++++ b/drivers/idle/intel_idle.c
+@@ -261,6 +261,7 @@ static int intel_idle(struct cpuidle_device *dev,
+ 	kt_before = ktime_get_real();
+ 
+ 	stop_critical_timings();
++	rcu_idle_enter();
+ 	if (!need_resched()) {
+ 
+ 		__monitor((void *)&current_thread_info()->flags, 0, 0);
+@@ -268,6 +269,7 @@ static int intel_idle(struct cpuidle_device *dev,
+ 		if (!need_resched())
+ 			__mwait(eax, ecx);
+ 	}
++	rcu_idle_exit();
+ 
+ 	start_critical_timings();
+ 
+
+  
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