On Tue, Nov 07, 2017 at 08:48:38AM -0700, Jason Gunthorpe wrote: > Can't you just use vmalloc and dma_map that? Other drivers follow that > approach..
You can't easily due to the flushing requirements. We used to do that in XFS and it led to problems. You need the page allocator + vmap + invalidate_kernel_vmap_range + flush_kernel_vmap_range to get the cache flushing right.
