https://bugs.freedesktop.org/show_bug.cgi?id=100979
--- Comment #12 from Przemek soprwa@gmail.com --- The valid mailing list post, when it comes to messages "swiotlb buffer is full" and "swiotlb: coherent allocation failed", is: https://lkml.org/lkml/2018/1/10/132. Thanks to Alex Deucher correcting me in another bug report.