diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
index a48fcce3f5f65edb70ca216583a87c7a1ae5a11c..4a7a3107d874038163a8f06c31902e8c9e4e9cce 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
@@ -45,13 +45,13 @@ struct rockchip_crtc_state {
  *
  * @crtc: array of enabled CRTCs, used to map from "pipe" to drm_crtc.
  * @num_pipe: number of pipes for this device.
+ * @mm_lock: protect drm_mm on multi-threads.
  */
 struct rockchip_drm_private {
 	struct drm_fb_helper fbdev_helper;
 	struct drm_gem_object *fbdev_bo;
 	struct drm_atomic_state *state;
 	struct iommu_domain *domain;
-	/* protect drm_mm on multi-threads */
 	struct mutex mm_lock;
 	struct drm_mm mm;
 	struct list_head psr_list;
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
index df9e57064f1983ae192413dfefb20fa3c9a8319f..b74ac717e56a502a647bf3a601c1166e7787ffa2 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_gem.c
@@ -29,12 +29,11 @@ static int rockchip_gem_iommu_map(struct rockchip_gem_object *rk_obj)
 	ssize_t ret;
 
 	mutex_lock(&private->mm_lock);
-
 	ret = drm_mm_insert_node_generic(&private->mm, &rk_obj->mm,
 					 rk_obj->base.size, PAGE_SIZE,
 					 0, 0);
-
 	mutex_unlock(&private->mm_lock);
+
 	if (ret < 0) {
 		DRM_ERROR("out of I/O virtual memory: %zd\n", ret);
 		return ret;
@@ -56,7 +55,9 @@ static int rockchip_gem_iommu_map(struct rockchip_gem_object *rk_obj)
 	return 0;
 
 err_remove_node:
+	mutex_lock(&private->mm_lock);
 	drm_mm_remove_node(&rk_obj->mm);
+	mutex_unlock(&private->mm_lock);
 
 	return ret;
 }