On Thu, Aug 15, 2019 at 06:48:39PM +0000, Koenig, Christian wrote: > Well, for the graphics case I absolutely need to keep the linear kernel > mapping. Because for certain use cases the memory is accessed by the kernel > all the time as well.
Then don't set DMA_ATTR_NO_KERNEL_MAPPING. At least for x86 and arm64 we should be able to support uncached allocations easily even without that, and I plan to support that for your use case. But if the driver is explicitly saying it doesn't want a permanent kernel mapping it makes sense to (optionally if the architecture can easily do it) unmap the memory from the kernel linear mapping.
