On 4/27/2018 11:54 AM, Robin Murphy wrote: > >> ubuntu@ubuntu:~/amdgpu$_./vectoradd_hip.exe >> [ 834.002206] create_process:620 >> [ 837.413021] Unable to handle kernel NULL pointer dereference at virtual address 00000018 > > £5 says that's sg_dma_len(NULL), which implies either that something's gone horribly wrong with the scatterlist DMA mapping such that the lengths don't match, or much more likely that ttm.dma_address is NULL and I've missed the tiny subtlety below. Does that fix matters? Turned out to be a null pointer problem after sg_next(). The following helped. + if (addrs && (dma_len == 0)) { dma_sg = sg_next(dma_sg); - dma_len = sg_dma_len(dma_sg); - addr = sg_dma_address(dma_sg); + if (dma_sg) { + dma_len = sg_dma_len(dma_sg); + addr = sg_dma_address(dma_sg); + } } -- Sinan Kaya Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc. Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel