[PATCH] Let list grow

[Joel Fernandes (Google)]

Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
---
 kernel/rcu/rcuperf.c |  2 +-
 kernel/rcu/tree.c    | 52 +++++++++++++++++++-------------------------
 2 files changed, 23 insertions(+), 31 deletions(-)

diff --git a/kernel/rcu/rcuperf.c b/kernel/rcu/rcuperf.c
index 34658760da5e..7dc831db89ae 100644
--- a/kernel/rcu/rcuperf.c
+++ b/kernel/rcu/rcuperf.c
@@ -654,7 +654,7 @@ kfree_perf_thread(void *arg)
 			}
 		}
 
-		schedule_timeout_uninterruptible(2);
+		cond_resched();
 	} while (!torture_must_stop() && ++l < kfree_loops);
 
 	kfree(alloc_ptrs);
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index bdbd483606ce..bab77220d8ac 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2595,7 +2595,7 @@ EXPORT_SYMBOL_GPL(call_rcu);
 
 
 /* Maximum number of jiffies to wait before draining batch */
-#define KFREE_DRAIN_JIFFIES 50
+#define KFREE_DRAIN_JIFFIES (HZ / 20)
 
 /*
  * Maximum number of kfree(s) to batch, if limit is hit
@@ -2684,27 +2684,19 @@ static void kfree_rcu_drain_unlock(struct kfree_rcu_cpu *krc,
 {
 	struct rcu_head *head, *next;
 
-	/* It is time to do bulk reclaim after grace period */
-	krc->monitor_todo = false;
+	/* It is time to do bulk reclaim after grace period. */
 	if (queue_kfree_rcu_work(krc)) {
 		spin_unlock_irqrestore(&krc->lock, flags);
 		return;
 	}
 
-	/*
-	 * Use non-batch regular call_rcu for kfree_rcu in case things are too
-	 * busy and batching of kfree_rcu could not be used.
-	 */
-	head = krc->head;
-	krc->head = NULL;
-	krc->kfree_batch_len = 0;
-	spin_unlock_irqrestore(&krc->lock, flags);
-
-	for (; head; head = next) {
-		next = head->next;
-		head->next = NULL;
-		__call_rcu(head, head->func, -1, 1);
+	/* Previous batch did not get free yet, let us try again soon. */
+	if (krc->monitor_todo == false) {
+		schedule_delayed_work_on(smp_processor_id(),
+				&krc->monitor_work,  KFREE_DRAIN_JIFFIES/4);
+		krc->monitor_todo = true;
 	}
+	spin_unlock_irqrestore(&krc->lock, flags);
 }
 
 /*
-- 
2.23.0.rc1.153.gdeed80330f-goog