diff --git a/include/linux/hmm.h b/include/linux/hmm.h
index bf013e9..0fa8ea3 100644
--- a/include/linux/hmm.h
+++ b/include/linux/hmm.h
@@ -86,7 +86,7 @@
 struct hmm {
 	struct mm_struct	*mm;
 	struct kref		kref;
-	struct mutex		lock;
+	spinlock_t		ranges_lock;
 	struct list_head	ranges;
 	struct list_head	mirrors;
 	struct mmu_notifier	mmu_notifier;
diff --git a/mm/hmm.c b/mm/hmm.c
index b224ea6..de35289 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -64,7 +64,7 @@ static struct hmm *hmm_get_or_create(struct mm_struct *mm)
 	init_rwsem(&hmm->mirrors_sem);
 	hmm->mmu_notifier.ops = NULL;
 	INIT_LIST_HEAD(&hmm->ranges);
-	mutex_init(&hmm->lock);
+	spin_lock_init(&hmm->ranges_lock);
 	kref_init(&hmm->kref);
 	hmm->notifiers = 0;
 	hmm->mm = mm;
@@ -144,6 +144,25 @@ static void hmm_release(struct mmu_notifier *mn, struct mm_struct *mm)
 	hmm_put(hmm);
 }
 
+static void notifiers_decrement(struct hmm *hmm)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&hmm->ranges_lock, flags);
+	hmm->notifiers--;
+	if (!hmm->notifiers) {
+		struct hmm_range *range;
+
+		list_for_each_entry(range, &hmm->ranges, list) {
+			if (range->valid)
+				continue;
+			range->valid = true;
+		}
+		wake_up_all(&hmm->wq);
+	}
+	spin_unlock_irqrestore(&hmm->ranges_lock, flags);
+}
+
 static int hmm_invalidate_range_start(struct mmu_notifier *mn,
 			const struct mmu_notifier_range *nrange)
 {
@@ -151,6 +170,7 @@ static int hmm_invalidate_range_start(struct mmu_notifier *mn,
 	struct hmm_mirror *mirror;
 	struct hmm_update update;
 	struct hmm_range *range;
+	unsigned long flags;
 	int ret = 0;
 
 	if (!kref_get_unless_zero(&hmm->kref))
@@ -161,12 +181,7 @@ static int hmm_invalidate_range_start(struct mmu_notifier *mn,
 	update.event = HMM_UPDATE_INVALIDATE;
 	update.blockable = mmu_notifier_range_blockable(nrange);
 
-	if (mmu_notifier_range_blockable(nrange))
-		mutex_lock(&hmm->lock);
-	else if (!mutex_trylock(&hmm->lock)) {
-		ret = -EAGAIN;
-		goto out;
-	}
+	spin_lock_irqsave(&hmm->ranges_lock, flags);
 	hmm->notifiers++;
 	list_for_each_entry(range, &hmm->ranges, list) {
 		if (update.end < range->start || update.start >= range->end)
@@ -174,7 +189,7 @@ static int hmm_invalidate_range_start(struct mmu_notifier *mn,
 
 		range->valid = false;
 	}
-	mutex_unlock(&hmm->lock);
+	spin_unlock_irqrestore(&hmm->ranges_lock, flags);
 
 	if (mmu_notifier_range_blockable(nrange))
 		down_read(&hmm->mirrors_sem);
@@ -182,16 +197,23 @@ static int hmm_invalidate_range_start(struct mmu_notifier *mn,
 		ret = -EAGAIN;
 		goto out;
 	}
-	list_for_each_entry(mirror, &hmm->mirrors, list) {
-		int ret;
 
-		ret = mirror->ops->sync_cpu_device_pagetables(mirror, &update);
-		if (!update.blockable && ret == -EAGAIN)
+	list_for_each_entry(mirror, &hmm->mirrors, list) {
+		int rc;
+
+		rc = mirror->ops->sync_cpu_device_pagetables(mirror, &update);
+		if (rc) {
+			if (WARN_ON(update.blockable || rc != -EAGAIN))
+				continue;
+			ret = -EAGAIN;
 			break;
+		}
 	}
 	up_read(&hmm->mirrors_sem);
 
 out:
+	if (ret)
+		notifiers_decrement(hmm);
 	hmm_put(hmm);
 	return ret;
 }
@@ -204,20 +226,7 @@ static void hmm_invalidate_range_end(struct mmu_notifier *mn,
 	if (!kref_get_unless_zero(&hmm->kref))
 		return;
 
-	mutex_lock(&hmm->lock);
-	hmm->notifiers--;
-	if (!hmm->notifiers) {
-		struct hmm_range *range;
-
-		list_for_each_entry(range, &hmm->ranges, list) {
-			if (range->valid)
-				continue;
-			range->valid = true;
-		}
-		wake_up_all(&hmm->wq);
-	}
-	mutex_unlock(&hmm->lock);
-
+	notifiers_decrement(hmm);
 	hmm_put(hmm);
 }
 
@@ -868,6 +877,7 @@ int hmm_range_register(struct hmm_range *range,
 {
 	unsigned long mask = ((1UL << page_shift) - 1UL);
 	struct hmm *hmm = mirror->hmm;
+	unsigned long flags;
 
 	range->valid = false;
 	range->hmm = NULL;
@@ -886,7 +896,7 @@ int hmm_range_register(struct hmm_range *range,
 		return -EFAULT;
 
 	/* Initialize range to track CPU page table updates. */
-	mutex_lock(&hmm->lock);
+	spin_lock_irqsave(&hmm->ranges_lock, flags);
 
 	range->hmm = hmm;
 	kref_get(&hmm->kref);
@@ -898,7 +908,7 @@ int hmm_range_register(struct hmm_range *range,
 	 */
 	if (!hmm->notifiers)
 		range->valid = true;
-	mutex_unlock(&hmm->lock);
+	spin_unlock_irqrestore(&hmm->ranges_lock, flags);
 
 	return 0;
 }
@@ -914,10 +924,11 @@ EXPORT_SYMBOL(hmm_range_register);
 void hmm_range_unregister(struct hmm_range *range)
 {
 	struct hmm *hmm = range->hmm;
+	unsigned long flags;
 
-	mutex_lock(&hmm->lock);
+	spin_lock_irqsave(&hmm->ranges_lock, flags);
 	list_del_init(&range->list);
-	mutex_unlock(&hmm->lock);
+	spin_unlock_irqrestore(&hmm->ranges_lock, flags);
 
 	/* Drop reference taken by hmm_range_register() */
 	mmput(hmm->mm);