On Wed, Jun 15, 2022 at 10:12:28AM -0600, Logan Gunthorpe wrote: > Consecutive zone device pages should not be merged into the same sgl > or bvec segment with other types of pages or if they belong to different > pgmaps. Otherwise getting the pgmap of a given segment is not possible > without scanning the entire segment. This helper returns true either if > both pages are not zone device pages or both pages are zone device > pages with the same pgmap. > > Add a helper to determine if zone device pages are mergeable and use > this helper in page_is_mergeable(). Any reason not to simply set REQ_NOMERGE for these requests? We can't merge for passthrough requests anyway, and genrally don't merge for direct I/O either, so adding all this overhead seems a bit pointless.
