On Tue, Aug 13, 2019 at 06:36:33PM -0700, Dan Williams wrote: > Section alignment constraints somewhat save us here. The only example > I can think of a PMD not containing a uniform pgmap association for > each pte is the case when the pgmap overlaps normal dram, i.e. shares > the same 'struct memory_section' for a given span. Otherwise, distinct > pgmaps arrange to manage their own exclusive sections (and now > subsections as of v5.3). Otherwise the implementation could not > guarantee different mapping lifetimes. > > That said, this seems to want a better mechanism to determine "pfn is > ZONE_DEVICE".
So I guess this patch is fine for now, and once you provide a better mechanism we can switch over to it?