On Fri, Jun 14, 2019 at 04:48:57PM +0200, Christoph Hellwig wrote: > 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). Ok, fair enough, have any pointers of drivers/core code that does this correctly? I can put it on my todo list, but might take a week or so... Ian, want to look into doing this sooner? thanks, greg k-h