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