revert "mm/memory-hotplug: fix lowmem count overflow when offline pages"

This reverts commit cea27eb2a202 ("mm/memory-hotplug: fix lowmem count
overflow when offline pages").

The fixed bug by commit cea27eb was fixed to another way by commit
3dcc0571cd64 ("mm: correctly update zone->managed_pages").  That commit
enhances memory_hotplug.c to adjust totalhigh_pages when hot-removing
memory, for details please refer to:

  http://marc.info/?l=linux-mm&m=136957578620221&w=2

As a result, commit cea27eb2a202 currently causes duplicated decreasing
of totalhigh_pages, thus the revert.

Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Reviewed-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/page_alloc.c

@@ -6366,10 +6366,6 @@ __offline_isolated_pages(unsigned long start_pfn, unsigned long end_pfn)
 		list_del(&page->lru);
 		rmv_page_order(page);
 		zone->free_area[order].nr_free--;
-#ifdef CONFIG_HIGHMEM
-		if (PageHighMem(page))
-			totalhigh_pages -= 1 << order;
-#endif
 		for (i = 0; i < (1 << order); i++)
 			SetPageReserved((page+i));
 		pfn += (1 << order);