On Fri, Jun 14, 2019 at 04:02:39PM +0200, Greg KH wrote: > Perhaps a hint as to how we can fix this up? This is the first time > I've heard of the comedi code not handling dma properly. It can be fixed by: a) never calling virt_to_page (or vmalloc_to_page for that matter) on dma allocation b) never remapping dma allocation with conflicting cache modes (no remapping should be doable after a) anyway).