In case of device resume after suspend, VQ notifier MR still valid.
Duplicated registrations explode memory block list and slow down device
resume.

Fixes: 44866521bd6e ("vhost-user: support registering external host notifiers")
Cc: tiwei.bie@intel.com
Cc: qemu-stable@nongnu.org
Cc: Yuwei Zhang <zhangyuwei.9149@bytedance.com>

Signed-off-by: Xueming Li <xuemingl@nvidia.com>
---
 hw/virtio/vhost-user.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/hw/virtio/vhost-user.c b/hw/virtio/vhost-user.c
index 2c8556237f..bf6e50223c 100644
--- a/hw/virtio/vhost-user.c
+++ b/hw/virtio/vhost-user.c
@@ -1526,8 +1526,9 @@ static int vhost_user_slave_handle_vring_host_notifier(struct vhost_dev *dev,
 
     name = g_strdup_printf("vhost-user/host-notifier@%p mmaps[%d]",
                            user, queue_idx);
-    memory_region_init_ram_device_ptr(&n->mr, OBJECT(vdev), name,
-                                      page_size, addr);
+    if (!n->mr.ram) /* Don't init again after suspend. */
+        memory_region_init_ram_device_ptr(&n->mr, OBJECT(vdev), name,
+                                          page_size, addr);
     g_free(name);
 
     if (virtio_queue_set_host_notifier_mr(vdev, queue_idx, &n->mr, true)) {
-- 
2.33.0