2 files changed, 36 insertions, 8 deletions

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index 79fa2db1595b..d62c04482228 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -366,11 +366,9 @@ static void rcu_eqs_enter_common(struct rcu_dynticks *rdtp, long long oldval,
  */
 static void rcu_eqs_enter(bool user)
 {
-        unsigned long flags;
         long long oldval;
         struct rcu_dynticks *rdtp;
 
-        local_irq_save(flags);
         rdtp = &__get_cpu_var(rcu_dynticks);
         oldval = rdtp->dynticks_nesting;
         WARN_ON_ONCE((oldval & DYNTICK_TASK_NEST_MASK) == 0);
@@ -379,7 +377,6 @@ static void rcu_eqs_enter(bool user)
         else
                 rdtp->dynticks_nesting -= DYNTICK_TASK_NEST_VALUE;
         rcu_eqs_enter_common(rdtp, oldval, user);
-        local_irq_restore(flags);
 }
 
 /**
@@ -396,7 +393,11 @@ static void rcu_eqs_enter(bool user)
  */
 void rcu_idle_enter(void)
 {
+        unsigned long flags;
+
+        local_irq_save(flags);
         rcu_eqs_enter(0);
+        local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(rcu_idle_enter);
 
@@ -411,6 +412,9 @@ EXPORT_SYMBOL_GPL(rcu_idle_enter);
  */
 void rcu_user_enter(void)
 {
+        unsigned long flags;
+        struct rcu_dynticks *rdtp;
+
         /*
          * Some contexts may involve an exception occuring in an irq,
          * leading to that nesting:
@@ -422,7 +426,15 @@ void rcu_user_enter(void)
         if (in_interrupt())
                 return;
 
-        rcu_eqs_enter(1);
+        WARN_ON_ONCE(!current->mm);
+
+        local_irq_save(flags);
+        rdtp = &__get_cpu_var(rcu_dynticks);
+        if (!rdtp->in_user) {
+                rdtp->in_user = true;
+                rcu_eqs_enter(1);
+        }
+        local_irq_restore(flags);
 }
 
 /**
@@ -516,11 +528,9 @@ static void rcu_eqs_exit_common(struct rcu_dynticks *rdtp, long long oldval,
  */
 static void rcu_eqs_exit(bool user)
 {
-        unsigned long flags;
         struct rcu_dynticks *rdtp;
         long long oldval;
 
-        local_irq_save(flags);
         rdtp = &__get_cpu_var(rcu_dynticks);
         oldval = rdtp->dynticks_nesting;
         WARN_ON_ONCE(oldval < 0);
@@ -529,7 +539,6 @@ static void rcu_eqs_exit(bool user)
         else
                 rdtp->dynticks_nesting = DYNTICK_TASK_EXIT_IDLE;
         rcu_eqs_exit_common(rdtp, oldval, user);
-        local_irq_restore(flags);
 }
 
 /**
@@ -545,7 +554,11 @@ static void rcu_eqs_exit(bool user)
  */
 void rcu_idle_exit(void)
 {
+        unsigned long flags;
+
+        local_irq_save(flags);
         rcu_eqs_exit(0);
+        local_irq_restore(flags);
 }
 EXPORT_SYMBOL_GPL(rcu_idle_exit);
 
@@ -558,6 +571,9 @@ EXPORT_SYMBOL_GPL(rcu_idle_exit);
  */
 void rcu_user_exit(void)
 {
+        unsigned long flags;
+        struct rcu_dynticks *rdtp;
+
         /*
          * Some contexts may involve an exception occuring in an irq,
          * leading to that nesting:
@@ -569,7 +585,13 @@ void rcu_user_exit(void)
         if (in_interrupt())
                 return;
 
-        rcu_eqs_exit(1);
+        local_irq_save(flags);
+        rdtp = &__get_cpu_var(rcu_dynticks);
+        if (rdtp->in_user) {
+                rdtp->in_user = false;
+                rcu_eqs_exit(1);
+        }
+        local_irq_restore(flags);
 }
 
 /**
@@ -2586,6 +2608,9 @@ rcu_boot_init_percpu_data(int cpu, struct rcu_state *rsp)
         rdp->dynticks = &per_cpu(rcu_dynticks, cpu);
         WARN_ON_ONCE(rdp->dynticks->dynticks_nesting != DYNTICK_TASK_EXIT_IDLE);
         WARN_ON_ONCE(atomic_read(&rdp->dynticks->dynticks) != 1);
+#ifdef CONFIG_RCU_USER_QS
+        WARN_ON_ONCE(rdp->dynticks->in_user);
+#endif
         rdp->cpu = cpu;
         rdp->rsp = rsp;
         raw_spin_unlock_irqrestore(&rnp->lock, flags);
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 7576fd4d8ce6..10cc2f9f8433 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -102,6 +102,9 @@ struct rcu_dynticks {
                                     /* idle-period nonlazy_posted snapshot. */
         int tick_nohz_enabled_snap; /* Previously seen value from sysfs. */
 #endif /* #ifdef CONFIG_RCU_FAST_NO_HZ */
+#ifdef CONFIG_RCU_USER_QS
+        bool in_user;               /* Is the CPU in userland from RCU POV? */
+#endif
 };
 
 /* RCU's kthread states for tracing. */