revert "mm: fix-up zone present pages"

Revert commit 7f1290f2f2a4 ("mm: fix-up zone present pages")

That patch tried to fix a issue when calculating zone->present_pages,
but it caused a regression on 32bit systems with HIGHMEM.  With that
change, reset_zone_present_pages() resets all zone->present_pages to
zero, and fixup_zone_present_pages() is called to recalculate
zone->present_pages when the boot allocator frees core memory pages into
buddy allocator.  Because highmem pages are not freed by bootmem
allocator, all highmem zones' present_pages becomes zero.

Various options for improving the situation are being discussed but for
now, let's return to the 3.6 code.

Cc: Jianguo Wu <wujianguo@huawei.com>
Cc: Jiang Liu <jiang.liu@huawei.com>
Cc: Petr Tesarik <ptesarik@suse.cz>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: David Rientjes <rientjes@google.com>
Tested-by: Chris Clayton <chris2553@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 0 insertions, 34 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index c91598b1b4c0..7bb35ac0964a 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6098,37 +6098,3 @@ void dump_page(struct page *page)
         dump_page_flags(page->flags);
         mem_cgroup_print_bad_page(page);
 }
-
-/* reset zone->present_pages */
-void reset_zone_present_pages(void)
-{
-        struct zone *z;
-        int i, nid;
-
-        for_each_node_state(nid, N_HIGH_MEMORY) {
-                for (i = 0; i < MAX_NR_ZONES; i++) {
-                        z = NODE_DATA(nid)->node_zones + i;
-                        z->present_pages = 0;
-                }
-        }
-}
-
-/* calculate zone's present pages in buddy system */
-void fixup_zone_present_pages(int nid, unsigned long start_pfn,
-                                unsigned long end_pfn)
-{
-        struct zone *z;
-        unsigned long zone_start_pfn, zone_end_pfn;
-        int i;
-
-        for (i = 0; i < MAX_NR_ZONES; i++) {
-                z = NODE_DATA(nid)->node_zones + i;
-                zone_start_pfn = z->zone_start_pfn;
-                zone_end_pfn = zone_start_pfn + z->spanned_pages;
-
-                /* if the two regions intersect */
-                if (!(zone_start_pfn >= end_pfn || zone_end_pfn <= start_pfn))
-                        z->present_pages += min(end_pfn, zone_end_pfn) -
-                                            max(start_pfn, zone_start_pfn);
-        }
-}