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>

4 files changed, 1 insertions, 53 deletions

diff --git a/mm/bootmem.c b/mm/bootmem.c
index 434be4ae7a04..f468185b3b28 100644
--- a/mm/bootmem.c
+++ b/mm/bootmem.c
@@ -198,8 +198,6 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
                         int order = ilog2(BITS_PER_LONG);
 
                         __free_pages_bootmem(pfn_to_page(start), order);
-                        fixup_zone_present_pages(page_to_nid(pfn_to_page(start)),
-                                        start, start + BITS_PER_LONG);
                         count += BITS_PER_LONG;
                         start += BITS_PER_LONG;
                 } else {
@@ -210,9 +208,6 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
                                 if (vec & 1) {
                                         page = pfn_to_page(start + off);
                                         __free_pages_bootmem(page, 0);
-                                        fixup_zone_present_pages(
-                                                page_to_nid(page),
-                                                start + off, start + off + 1);
                                         count++;
                                 }
                                 vec >>= 1;
@@ -226,11 +221,8 @@ static unsigned long __init free_all_bootmem_core(bootmem_data_t *bdata)
         pages = bdata->node_low_pfn - bdata->node_min_pfn;
         pages = bootmem_bootmap_pages(pages);
         count += pages;
-        while (pages--) {
-                fixup_zone_present_pages(page_to_nid(page),
-                                page_to_pfn(page), page_to_pfn(page) + 1);
+        while (pages--)
                 __free_pages_bootmem(page++, 0);
-        }
 
         bdebug("nid=%td released=%lx\n", bdata - bootmem_node_data, count);
 
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 56b758ae57d2..e4eeacae2b91 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -106,7 +106,6 @@ static void get_page_bootmem(unsigned long info,  struct page *page,
 void __ref put_page_bootmem(struct page *page)
 {
         unsigned long type;
-        struct zone *zone;
 
         type = (unsigned long) page->lru.next;
         BUG_ON(type < MEMORY_HOTPLUG_MIN_BOOTMEM_TYPE ||
@@ -117,12 +116,6 @@ void __ref put_page_bootmem(struct page *page)
                 set_page_private(page, 0);
                 INIT_LIST_HEAD(&page->lru);
                 __free_pages_bootmem(page, 0);
-
-                zone = page_zone(page);
-                zone_span_writelock(zone);
-                zone->present_pages++;
-                zone_span_writeunlock(zone);
-                totalram_pages++;
         }
 
 }
diff --git a/mm/nobootmem.c b/mm/nobootmem.c
index 714d5d650470..bd82f6b31411 100644
--- a/mm/nobootmem.c
+++ b/mm/nobootmem.c
@@ -116,8 +116,6 @@ static unsigned long __init __free_memory_core(phys_addr_t start,
                 return 0;
 
         __free_pages_memory(start_pfn, end_pfn);
-        fixup_zone_present_pages(pfn_to_nid(start >> PAGE_SHIFT),
-                        start_pfn, end_pfn);
 
         return end_pfn - start_pfn;
 }
@@ -128,7 +126,6 @@ unsigned long __init free_low_memory_core_early(int nodeid)
         phys_addr_t start, end, size;
         u64 i;
 
-        reset_zone_present_pages();
         for_each_free_mem_range(i, MAX_NUMNODES, &start, &end, NULL)
                 count += __free_memory_core(start, end);
 
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);
-        }
-}