On Mon, Mar 30, 2020 at 06:15:41PM +0900, Tokunori Ikegami wrote:

But there is a case that the command data length is limited by 512KB.
I am not sure about this condition so needed more investigation.

Your memory is too fragmented. You need more physically contiguous
memory or you'll hit the segment limit before you hit the length
limit. Try allocating huge pages.