!748 fix question that release all loaded model memory when memory is not enough

From: @wan_xuelei
Reviewed-by: @xchu42,@ji_chen
Signed-off-by: @ji_chen

ge/graph/manager/graph_manager.cc

@@ -2421,6 +2421,13 @@ Status GraphManager::CheckAndReleaseMemory(const GeModelPtr &ge_model, const Gra
       continue;
     }
     auto model_id = model->GetModelId();
+    // unload model not release
+    bool is_unknown_shape = false;
+    GE_CHK_STATUS_RET(model->CheckIsUnknownShape(is_unknown_shape));
+    if (is_unknown_shape) {
+      GELOGD("model_id[%u] graph_id[%u] is unknown model, not release memory", model_id, graph_id);
+      continue;
+    }
     // not loaded,no need unload
     if (!it.second->GetLoadFlag()) {
       GELOGI("CheckAndReleaseMemory graph[%u] has not been loaded.", graph_id);