diff --git a/drivers/gpu/drm/i915/i915_gem_userptr.c b/drivers/gpu/drm/i915/i915_gem_userptr.c
index d3213fdefafc..9056aa5b00f3 100644
--- a/drivers/gpu/drm/i915/i915_gem_userptr.c
+++ b/drivers/gpu/drm/i915/i915_gem_userptr.c
@@ -50,7 +50,6 @@ struct i915_mmu_notifier {
 	struct mmu_notifier mn;
 	struct rb_root objects;
 	struct list_head linear;
-	unsigned long serial;
 	bool has_linear;
 };
 
@@ -59,14 +58,16 @@ struct i915_mmu_object {
 	struct interval_tree_node it;
 	struct list_head link;
 	struct drm_i915_gem_object *obj;
+	struct work_struct work;
 	bool active;
 	bool is_linear;
 };
 
-static unsigned long cancel_userptr(struct drm_i915_gem_object *obj)
+static void __cancel_userptr__worker(struct work_struct *work)
 {
+	struct i915_mmu_object *mo = container_of(work, typeof(*mo), work);
+	struct drm_i915_gem_object *obj = mo->obj;
 	struct drm_device *dev = obj->base.dev;
-	unsigned long end;
 
 	mutex_lock(&dev->struct_mutex);
 	/* Cancel any active worker and force us to re-evaluate gup */
@@ -89,46 +90,26 @@ static unsigned long cancel_userptr(struct drm_i915_gem_object *obj)
 		dev_priv->mm.interruptible = was_interruptible;
 	}
 
-	end = obj->userptr.ptr + obj->base.size;
-
 	drm_gem_object_unreference(&obj->base);
 	mutex_unlock(&dev->struct_mutex);
-
-	return end;
 }
 
-static void *invalidate_range__linear(struct i915_mmu_notifier *mn,
-				      struct mm_struct *mm,
-				      unsigned long start,
-				      unsigned long end)
+static unsigned long cancel_userptr(struct i915_mmu_object *mo)
 {
-	struct i915_mmu_object *mo;
-	unsigned long serial;
-
-restart:
-	serial = mn->serial;
-	list_for_each_entry(mo, &mn->linear, link) {
-		struct drm_i915_gem_object *obj;
-
-		if (mo->it.last < start || mo->it.start > end)
-			continue;
-
-		obj = mo->obj;
-
-		if (!mo->active ||
-		    !kref_get_unless_zero(&obj->base.refcount))
-			continue;
-
-		spin_unlock(&mn->lock);
-
-		cancel_userptr(obj);
-
-		spin_lock(&mn->lock);
-		if (serial != mn->serial)
-			goto restart;
-	}
+	unsigned long end = mo->obj->userptr.ptr + mo->obj->base.size;
+
+	/* The mmu_object is released late when destroying the
+	 * GEM object so it is entirely possible to gain a
+	 * reference on an object in the process of being freed
+	 * since our serialisation is via the spinlock and not
+	 * the struct_mutex - and consequently use it after it
+	 * is freed and then double free it.
+	 */
+	if (mo->active &&
+	    kref_get_unless_zero(&mo->obj->base.refcount))
+		schedule_work(&mo->work);
 
-	return NULL;
+	return end;
 }
 
 static void i915_gem_userptr_mn_invalidate_range_start(struct mmu_notifier *_mn,
@@ -136,45 +117,32 @@ static void i915_gem_userptr_mn_invalidate_range_start(struct mmu_notifier *_mn,
 						       unsigned long start,
 						       unsigned long end)
 {
-	struct i915_mmu_notifier *mn = container_of(_mn, struct i915_mmu_notifier, mn);
-	struct interval_tree_node *it = NULL;
-	unsigned long next = start;
-	unsigned long serial = 0;
-
-	end--; /* interval ranges are inclusive, but invalidate range is exclusive */
-	while (next < end) {
-		struct drm_i915_gem_object *obj = NULL;
-
-		spin_lock(&mn->lock);
-		if (mn->has_linear)
-			it = invalidate_range__linear(mn, mm, start, end);
-		else if (serial == mn->serial)
-			it = interval_tree_iter_next(it, next, end);
-		else
-			it = interval_tree_iter_first(&mn->objects, start, end);
-		if (it != NULL) {
-			struct i915_mmu_object *mo =
-				container_of(it, struct i915_mmu_object, it);
-
-			/* The mmu_object is released late when destroying the
-			 * GEM object so it is entirely possible to gain a
-			 * reference on an object in the process of being freed
-			 * since our serialisation is via the spinlock and not
-			 * the struct_mutex - and consequently use it after it
-			 * is freed and then double free it.
-			 */
-			if (mo->active &&
-			    kref_get_unless_zero(&mo->obj->base.refcount))
-				obj = mo->obj;
+	struct i915_mmu_notifier *mn =
+		container_of(_mn, struct i915_mmu_notifier, mn);
+	struct i915_mmu_object *mo;
+
+	/* interval ranges are inclusive, but invalidate range is exclusive */
+	end--;
 
-			serial = mn->serial;
+	spin_lock(&mn->lock);
+	if (mn->has_linear) {
+		list_for_each_entry(mo, &mn->linear, link) {
+			if (mo->it.last < start || mo->it.start > end)
+				continue;
+
+			cancel_userptr(mo);
 		}
-		spin_unlock(&mn->lock);
-		if (obj == NULL)
-			return;
+	} else {
+		struct interval_tree_node *it;
 
-		next = cancel_userptr(obj);
+		it = interval_tree_iter_first(&mn->objects, start, end);
+		while (it) {
+			mo = container_of(it, struct i915_mmu_object, it);
+			start = cancel_userptr(mo);
+			it = interval_tree_iter_next(it, start, end);
+		}
 	}
+	spin_unlock(&mn->lock);
 }
 
 static const struct mmu_notifier_ops i915_gem_userptr_notifier = {
@@ -194,7 +162,6 @@ i915_mmu_notifier_create(struct mm_struct *mm)
 	spin_lock_init(&mn->lock);
 	mn->mn.ops = &i915_gem_userptr_notifier;
 	mn->objects = RB_ROOT;
-	mn->serial = 1;
 	INIT_LIST_HEAD(&mn->linear);
 	mn->has_linear = false;
 
@@ -208,12 +175,6 @@ i915_mmu_notifier_create(struct mm_struct *mm)
 	return mn;
 }
 
-static void __i915_mmu_notifier_update_serial(struct i915_mmu_notifier *mn)
-{
-	if (++mn->serial == 0)
-		mn->serial = 1;
-}
-
 static int
 i915_mmu_notifier_add(struct drm_device *dev,
 		      struct i915_mmu_notifier *mn,
@@ -260,10 +221,9 @@ i915_mmu_notifier_add(struct drm_device *dev,
 	} else
 		interval_tree_insert(&mo->it, &mn->objects);
 
-	if (ret == 0) {
+	if (ret == 0)
 		list_add(&mo->link, &mn->linear);
-		__i915_mmu_notifier_update_serial(mn);
-	}
+
 	spin_unlock(&mn->lock);
 	mutex_unlock(&dev->struct_mutex);
 
@@ -291,7 +251,6 @@ i915_mmu_notifier_del(struct i915_mmu_notifier *mn,
 		mn->has_linear = i915_mmu_notifier_has_linear(mn);
 	else
 		interval_tree_remove(&mo->it, &mn->objects);
-	__i915_mmu_notifier_update_serial(mn);
 	spin_unlock(&mn->lock);
 }
 
@@ -358,6 +317,7 @@ i915_gem_userptr_init__mmu_notifier(struct drm_i915_gem_object *obj,
 	mo->it.start = obj->userptr.ptr;
 	mo->it.last = mo->it.start + obj->base.size - 1;
 	mo->obj = obj;
+	INIT_WORK(&mo->work, __cancel_userptr__worker);
 
 	ret = i915_mmu_notifier_add(obj->base.dev, mn, mo);
 	if (ret) {
@@ -546,10 +506,12 @@ err:
 	return ret;
 }
 
-static void
+static int
 __i915_gem_userptr_set_active(struct drm_i915_gem_object *obj,
 			      bool value)
 {
+	int ret = 0;
+
 	/* During mm_invalidate_range we need to cancel any userptr that
 	 * overlaps the range being invalidated. Doing so requires the
 	 * struct_mutex, and that risks recursion. In order to cause
@@ -562,12 +524,20 @@ __i915_gem_userptr_set_active(struct drm_i915_gem_object *obj,
 	 */
 #if defined(CONFIG_MMU_NOTIFIER)
 	if (obj->userptr.mmu_object == NULL)
-		return;
+		return 0;
 
 	spin_lock(&obj->userptr.mmu_object->mn->lock);
-	obj->userptr.mmu_object->active = value;
+	/* In order to serialise get_pages with an outstanding
+	 * cancel_userptr, we must drop the struct_mutex and try again.
+	 */
+	if (!value || !work_pending(&obj->userptr.mmu_object->work))
+		obj->userptr.mmu_object->active = value;
+	else
+		ret = -EAGAIN;
 	spin_unlock(&obj->userptr.mmu_object->mn->lock);
 #endif
+
+	return ret;
 }
 
 static void
