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.
This seems to be a leftover from ancient times where the memmap was initialized when adding memory and we wanted to check for already onlined memory. Cc: Andrew Morton <[email protected]> Cc: Oscar Salvador <[email protected]> Cc: Michal Hocko <[email protected]> Cc: Pavel Tatashin <[email protected]> Cc: Dan Williams <[email protected]> Signed-off-by: David Hildenbrand <[email protected]> --- mm/memory_hotplug.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 3706a137d880..10ad970f3f14 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -653,9 +653,7 @@ static int online_pages_range(unsigned long start_pfn, unsigned long nr_pages, { unsigned long onlined_pages = *(unsigned long *)arg; - if (PageReserved(pfn_to_page(start_pfn))) - onlined_pages += online_pages_blocks(start_pfn, nr_pages); - + onlined_pages += online_pages_blocks(start_pfn, nr_pages); online_mem_sections(start_pfn, start_pfn + nr_pages); *(unsigned long *)arg = onlined_pages; -- 2.21.0
