1 files changed, 32 insertions, 23 deletions

diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 09b685daee3d..beeeac9e0e3e 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -1804,8 +1804,8 @@ static void pool_mayday_timeout(unsigned long __pool)
 	struct worker_pool *pool = (void *)__pool;
 	struct work_struct *work;
 
-	spin_lock_irq(&wq_mayday_lock);		/* for wq->maydays */
-	spin_lock(&pool->lock);
+	spin_lock_irq(&pool->lock);
+	spin_lock(&wq_mayday_lock);		/* for wq->maydays */
 
 	if (need_to_create_worker(pool)) {
 		/*
@@ -1818,8 +1818,8 @@ static void pool_mayday_timeout(unsigned long __pool)
 			send_mayday(work);
 	}
 
-	spin_unlock(&pool->lock);
-	spin_unlock_irq(&wq_mayday_lock);
+	spin_unlock(&wq_mayday_lock);
+	spin_unlock_irq(&pool->lock);
 
 	mod_timer(&pool->mayday_timer, jiffies + MAYDAY_INTERVAL);
 }
@@ -1841,17 +1841,11 @@ static void pool_mayday_timeout(unsigned long __pool)
  * spin_lock_irq(pool->lock) which may be released and regrabbed
  * multiple times.  Does GFP_KERNEL allocations.  Called only from
  * manager.
- *
- * Return:
- * %false if no action was taken and pool->lock stayed locked, %true
- * otherwise.
  */
-static bool maybe_create_worker(struct worker_pool *pool)
+static void maybe_create_worker(struct worker_pool *pool)
 __releases(&pool->lock)
 __acquires(&pool->lock)
 {
-	if (!need_to_create_worker(pool))
-		return false;
 restart:
 	spin_unlock_irq(&pool->lock);
 
@@ -1877,7 +1871,6 @@ restart:
 	 */
 	if (need_to_create_worker(pool))
 		goto restart;
-	return true;
 }
 
 /**
@@ -1897,16 +1890,14 @@ restart:
  * multiple times.  Does GFP_KERNEL allocations.
  *
  * Return:
- * %false if the pool don't need management and the caller can safely start
- * processing works, %true indicates that the function released pool->lock
- * and reacquired it to perform some management function and that the
- * conditions that the caller verified while holding the lock before
- * calling the function might no longer be true.
+ * %false if the pool doesn't need management and the caller can safely
+ * start processing works, %true if management function was performed and
+ * the conditions that the caller verified before calling the function may
+ * no longer be true.
  */
 static bool manage_workers(struct worker *worker)
 {
 	struct worker_pool *pool = worker->pool;
-	bool ret = false;
 
 	/*
 	 * Anyone who successfully grabs manager_arb wins the arbitration
@@ -1919,12 +1910,12 @@ static bool manage_workers(struct worker *worker)
 	 * actual management, the pool may stall indefinitely.
 	 */
 	if (!mutex_trylock(&pool->manager_arb))
-		return ret;
+		return false;
 
-	ret |= maybe_create_worker(pool);
+	maybe_create_worker(pool);
 
 	mutex_unlock(&pool->manager_arb);
-	return ret;
+	return true;
 }
 
 /**
@@ -2248,12 +2239,30 @@ repeat:
 		 * Slurp in all works issued via this workqueue and
 		 * process'em.
 		 */
-		WARN_ON_ONCE(!list_empty(&rescuer->scheduled));
+		WARN_ON_ONCE(!list_empty(scheduled));
 		list_for_each_entry_safe(work, n, &pool->worklist, entry)
 			if (get_work_pwq(work) == pwq)
 				move_linked_works(work, scheduled, &n);
 
-		process_scheduled_works(rescuer);
+		if (!list_empty(scheduled)) {
+			process_scheduled_works(rescuer);
+
+			/*
+			 * The above execution of rescued work items could
+			 * have created more to rescue through
+			 * pwq_activate_first_delayed() or chained
+			 * queueing.  Let's put @pwq back on mayday list so
+			 * that such back-to-back work items, which may be
+			 * being used to relieve memory pressure, don't
+			 * incur MAYDAY_INTERVAL delay inbetween.
+			 */
+			if (need_to_create_worker(pool)) {
+				spin_lock(&wq_mayday_lock);
+				get_pwq(pwq);
+				list_move_tail(&pwq->mayday_node, &wq->maydays);
+				spin_unlock(&wq_mayday_lock);
+			}
+		}
 
 		/*
 		 * Put the reference grabbed by send_mayday().  @pool won't