Computer hang when my driver write to graphic card memory (GPUDirect)

Hello,

I need your help!

I am developing Linux device driver for a PCIe card receiving data and writing it to the graphic card memory for processing.

I work on Ubuntu 18.04 with kernel 4.15.0-45
I use a Quadro K620 graphic card

The drive code call nvidia_p2p_… function as described in the documentation and no error occure. The physical address I get are inside the very large BAR of the graphic card. So all is looking great!

When my PCIe card first try to write data to the graphic card memory, the computer completely hang and I cannot get more information. I need to press the reset button to get back on my feet. I tried with and without enabling the iommu and in both case I got the same result.

Does someone here, already get such behavior? What is causing it? Do you know some way to get more information about what is happening?

Any help will be appreciated,

Martin

Oups I forget,

I use the driver 410.93 and CUDA 10.0