On Tue, 26 Jan 2016 14:33:48 -0800 Dan Williams <dan.j.williams@xxxxxxxxx> wrote: > >> Towards this end, alias ZONE_DMA and ZONE_DEVICE to work around needing > >> to maintain a unique zone number for ZONE_DEVICE. Record the geometry > >> of ZONE_DMA at init (->init_spanned_pages) and use that information in > >> is_zone_device_page() to differentiate pages allocated via > >> devm_memremap_pages() vs true ZONE_DMA pages. Otherwise, use the > >> simpler definition of is_zone_device_page() when ZONE_DMA is turned off. > >> > >> Note that this also teaches the memory hot remove path that the zone may > >> not have sections for all pfn spans (->zone_dyn_start_pfn). > >> > >> A user visible implication of this change is potentially an unexpectedly > >> high "spanned" value in /proc/zoneinfo for the DMA zone. > > > > Well, all these icky tricks are to avoid increasing ZONES_SHIFT, yes? > > Is it possible to just use ZONES_SHIFT=3? > > Last I tried I hit this warning in mm/memory.c > > #warning Unfortunate NUMA and NUMA Balancing config, growing > page-frame for last_cpupid. Well yes, it may take a bit of work - perhaps salvaging a bit from somewhere else if poss. But that might provide a better overall solution so could you please have a think? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>