On 14.08.19 16:19, Michal Hocko wrote: > On Fri 09-08-19 14:57:00, David Hildenbrand wrote: >> move_pfn_range_to_zone() will set all pages to PG_reserved via >> memmap_init_zone(). The only way a page could no longer be reserved >> would be if a MEM_GOING_ONLINE notifier would clear PG_reserved - which >> is not done (the online_page callback is used for that purpose by >> e.g., Hyper-V instead). walk_system_ram_range() will never call >> online_pages_range() with duplicate PFNs, so drop the PageReserved() check. >> >> Simplify the handling, as online_pages always corresponds to nr_pages. >> There is no need for online_pages_blocks() anymore. > > This would be easier to review if split up into two patches. One that > only performs cleanup without any other changes and the PageReserved > check. I like the check going away and we should get rid of the > dependency on the Reserved bit completely. Yes, makes sense. > > Other than that I find the start_pfn and pfn being used both for > iteration each a different way really confusing and I cannot convince > myself it is even correct because I didn't bother to look deeper as > I simply think that the order manipulation from the previous is just > making things worse at this moment. If the problem is even real then it > can be done on top instead with some real example of the memory layout > that breaks. Yes, I'll rework this. Only "pfn" should be used in the loop (it seems to be correct but confusing I agree). -- Thanks, David / dhildenb
