Resize the Qt/QML application window by dragging mouse around the window border then it will show garbage

I have a Qt/QML application, with version Qt 5.5.1. On re-sizing the mainwindow horizontally/vertically, it showing garbage contained at the end.

[Note]
1. The issue is relative to DRAM size. After increasing DRAM size from 2GB to 4GB, the issue disappeared.
2. The issue could be reproduced with 2GB DRAM module on CRB.