diff --git a/Documentation/core-api/workqueue.rst b/Documentation/core-api/workqueue.rst
index 16f861c9791e..e295835fc116 100644
--- a/Documentation/core-api/workqueue.rst
+++ b/Documentation/core-api/workqueue.rst
@@ -245,8 +245,8 @@ CPU which can be assigned to the work items of a wq. For example, with
 at the same time per CPU. This is always a per-CPU attribute, even for
 unbound workqueues.
 
-The maximum limit for ``@max_active`` is 512 and the default value used
-when 0 is specified is 256. These values are chosen sufficiently high
+The maximum limit for ``@max_active`` is 2048 and the default value used
+when 0 is specified is 1024. These values are chosen sufficiently high
 such that they are not the limiting factor while providing protection in
 runaway cases.
 
@@ -357,6 +357,11 @@ Guidelines
   difference in execution characteristics between using a dedicated wq
   and a system wq.
 
+  Note: If something may generate more than @max_active outstanding
+  work items (do stress test your producers), it may saturate a system
+  wq and potentially lead to deadlock. It should utilize its own
+  dedicated workqueue rather than the system wq.
+
 * Unless work items are expected to consume a huge amount of CPU
   cycles, using a bound wq is usually beneficial due to the increased
   level of locality in wq operations and work item execution.
diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
index 59c2695e12e7..b0dc957c3e56 100644
--- a/include/linux/workqueue.h
+++ b/include/linux/workqueue.h
@@ -412,7 +412,7 @@ enum wq_flags {
 };
 
 enum wq_consts {
-	WQ_MAX_ACTIVE		= 512,	  /* I like 512, better ideas? */
+	WQ_MAX_ACTIVE		= 2048,	  /* I like 2048, better ideas? */
 	WQ_UNBOUND_MAX_ACTIVE	= WQ_MAX_ACTIVE,
 	WQ_DFL_ACTIVE		= WQ_MAX_ACTIVE / 2,
 
diff --git a/kernel/workqueue.c b/kernel/workqueue.c
index 9949ffad8df0..8b07576814a5 100644
--- a/kernel/workqueue.c
+++ b/kernel/workqueue.c
@@ -3833,16 +3833,28 @@ static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq,
 {
 	bool wait = false;
 	struct pool_workqueue *pwq;
+	struct worker_pool *current_pool = NULL;
 
 	if (flush_color >= 0) {
 		WARN_ON_ONCE(atomic_read(&wq->nr_pwqs_to_flush));
 		atomic_set(&wq->nr_pwqs_to_flush, 1);
 	}
 
+	/*
+	 * For unbound workqueue, pwqs will map to only a few pools.
+	 * Most of the time, pwqs within the same pool will be linked
+	 * sequentially to wq->pwqs by cpu index. So in the majority
+	 * of pwq iters, the pool is the same, only doing lock/unlock
+	 * if the pool has changed. This can largely reduce expensive
+	 * lock operations.
+	 */
 	for_each_pwq(pwq, wq) {
-		struct worker_pool *pool = pwq->pool;
-
-		raw_spin_lock_irq(&pool->lock);
+		if (current_pool != pwq->pool) {
+			if (likely(current_pool))
+				raw_spin_unlock_irq(&current_pool->lock);
+			current_pool = pwq->pool;
+			raw_spin_lock_irq(&current_pool->lock);
+		}
 
 		if (flush_color >= 0) {
 			WARN_ON_ONCE(pwq->flush_color != -1);
@@ -3859,9 +3871,11 @@ static bool flush_workqueue_prep_pwqs(struct workqueue_struct *wq,
 			pwq->work_color = work_color;
 		}
 
-		raw_spin_unlock_irq(&pool->lock);
 	}
 
+	if (current_pool)
+		raw_spin_unlock_irq(&current_pool->lock);
+
 	if (flush_color >= 0 && atomic_dec_and_test(&wq->nr_pwqs_to_flush))
 		complete(&wq->first_flusher->done);