How to kick DMA-send from Linux kernel module

Hello,

Do you have any idea to kick DMA-send from Linux kernel module?
It is equivalent to cuMemcpyHtoD() in user space, excepting the source buffer is page-cache of Linux kernel.

I’m now under investigation how to send some buffered storage blocks to GPU RAM, without intermediation of userspace.
However, less documentations are provided except for GPUDirect RDMA portion, and relevant implementation is in the portion of closed driver…

Thanks,