struct nvkm_vram *vram = nvkm_vram(memory);
        struct nvkm_mm_node *next = vram->mn;
        struct nvkm_mm_node *node;
-       mutex_lock(&vram->ram->fb->subdev.mutex);
+       mutex_lock(&vram->ram->mutex);
        while ((node = next)) {
                next = node->next;
                nvkm_mm_free(&vram->ram->vram, &node);
        }
-       mutex_unlock(&vram->ram->fb->subdev.mutex);
+       mutex_unlock(&vram->ram->mutex);
        return vram;
 }
 
        vram->page = page;
        *pmemory = &vram->memory;
 
-       mutex_lock(&ram->fb->subdev.mutex);
+       mutex_lock(&ram->mutex);
        node = &vram->mn;
        do {
                if (back)
                else
                        ret = nvkm_mm_head(mm, heap, type, max, min, align, &r);
                if (ret) {
-                       mutex_unlock(&ram->fb->subdev.mutex);
+                       mutex_unlock(&ram->mutex);
                        nvkm_memory_unref(pmemory);
                        return ret;
                }
                node = &r->next;
                max -= r->length;
        } while (max);
-       mutex_unlock(&ram->fb->subdev.mutex);
+       mutex_unlock(&ram->mutex);
        return 0;
 }
 
                if (ram->func->dtor)
                        *pram = ram->func->dtor(ram);
                nvkm_mm_fini(&ram->vram);
+               mutex_destroy(&ram->mutex);
                kfree(*pram);
                *pram = NULL;
        }
        ram->fb = fb;
        ram->type = type;
        ram->size = size;
+       mutex_init(&ram->mutex);
 
        if (!nvkm_mm_initialised(&ram->vram)) {
                ret = nvkm_mm_init(&ram->vram, NVKM_RAM_MM_NORMAL, 0,