3 files changed, 19 insertions, 1 deletions

diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index c0ed3765ec39..4ec4b14cfba6 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -1403,7 +1403,10 @@ static void rcu_do_batch(struct rcu_state *rsp, struct rcu_data *rdp)
                 debug_rcu_head_unqueue(list);
                 __rcu_reclaim(rsp->name, list);
                 list = next;
-                if (++count >= bl)
+                /* Stop only if limit reached and CPU has something to do. */
+                if (++count >= bl &&
+                    (need_resched() ||
+                     (!is_idle_task(current) && !rcu_is_callbacks_kthread())))
                         break;
         }
 
diff --git a/kernel/rcutree.h b/kernel/rcutree.h
index 9bcfbc9d16c6..fddff92d6676 100644
--- a/kernel/rcutree.h
+++ b/kernel/rcutree.h
@@ -455,6 +455,7 @@ static void __init __rcu_init_preempt(void);
 static void rcu_initiate_boost(struct rcu_node *rnp, unsigned long flags);
 static void rcu_preempt_boost_start_gp(struct rcu_node *rnp);
 static void invoke_rcu_callbacks_kthread(void);
+static bool rcu_is_callbacks_kthread(void);
 #ifdef CONFIG_RCU_BOOST
 static void rcu_preempt_do_callbacks(void);
 static void rcu_boost_kthread_setaffinity(struct rcu_node *rnp,
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index dbcea6b93aea..adb6e666c6f4 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -1337,6 +1337,15 @@ static void invoke_rcu_callbacks_kthread(void)
 }
 
 /*
+ * Is the current CPU running the RCU-callbacks kthread?
+ * Caller must have preemption disabled.
+ */
+static bool rcu_is_callbacks_kthread(void)
+{
+        return __get_cpu_var(rcu_cpu_kthread_task) == current;
+}
+
+/*
  * Set the affinity of the boost kthread.  The CPU-hotplug locks are
  * held, so no one should be messing with the existence of the boost
  * kthread.
@@ -1780,6 +1789,11 @@ static void invoke_rcu_callbacks_kthread(void)
         WARN_ON_ONCE(1);
 }
 
+static bool rcu_is_callbacks_kthread(void)
+{
+        return false;
+}
+
 static void rcu_preempt_boost_start_gp(struct rcu_node *rnp)
 {
 }