mm: add & use zone_end_pfn() and zone_spans_pfn()

Add 2 helpers (zone_end_pfn() and zone_spans_pfn()) to reduce code
duplication.

This also switches to using them in compaction (where an additional
variable needed to be renamed), page_alloc, vmstat, memory_hotplug, and
kmemleak.

Note that in compaction.c I avoid calling zone_end_pfn() repeatedly
because I expect at some point the sycronization issues with start_pfn &
spanned_pages will need fixing, either by actually using the seqlock or
clever memory barrier usage.

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Cc: David Hansen <dave@linux.vnet.ibm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 13 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 64c83a8c3220..a3687afc5917 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -250,9 +250,7 @@ static int page_outside_zone_boundaries(struct zone *zone, struct page *page)
 
         do {
                 seq = zone_span_seqbegin(zone);
-                if (pfn >= zone->zone_start_pfn + zone->spanned_pages)
-                        ret = 1;
-                else if (pfn < zone->zone_start_pfn)
+                if (!zone_spans_pfn(zone, pfn))
                         ret = 1;
         } while (zone_span_seqretry(zone, seq));
 
@@ -990,9 +988,9 @@ int move_freepages_block(struct zone *zone, struct page *page,
         end_pfn = start_pfn + pageblock_nr_pages - 1;
 
         /* Do not cross zone boundaries */
-        if (start_pfn < zone->zone_start_pfn)
+        if (!zone_spans_pfn(zone, start_pfn))
                 start_page = page;
-        if (end_pfn >= zone->zone_start_pfn + zone->spanned_pages)
+        if (!zone_spans_pfn(zone, end_pfn))
                 return 0;
 
         return move_freepages(zone, start_page, end_page, migratetype);
@@ -1286,7 +1284,7 @@ void mark_free_pages(struct zone *zone)
 
         spin_lock_irqsave(&zone->lock, flags);
 
-        max_zone_pfn = zone->zone_start_pfn + zone->spanned_pages;
+        max_zone_pfn = zone_end_pfn(zone);
         for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
                 if (pfn_valid(pfn)) {
                         struct page *page = pfn_to_page(pfn);
@@ -3798,7 +3796,7 @@ static void setup_zone_migrate_reserve(struct zone *zone)
          * the block.
          */
         start_pfn = zone->zone_start_pfn;
-        end_pfn = start_pfn + zone->spanned_pages;
+        end_pfn = zone_end_pfn(zone);
         start_pfn = roundup(start_pfn, pageblock_nr_pages);
         reserve = roundup(min_wmark_pages(zone), pageblock_nr_pages) >>
                                                         pageblock_order;
@@ -3912,7 +3910,7 @@ void __meminit memmap_init_zone(unsigned long size, int nid, unsigned long zone,
                  * pfn out of zone.
                  */
                 if ((z->zone_start_pfn <= pfn)
-                    && (pfn < z->zone_start_pfn + z->spanned_pages)
+                    && (pfn < zone_end_pfn(z))
                     && !(pfn & (pageblock_nr_pages - 1)))
                         set_pageblock_migratetype(page, MIGRATE_MOVABLE);
 
@@ -4713,7 +4711,7 @@ static void __init_refok alloc_node_mem_map(struct pglist_data *pgdat)
                  * for the buddy allocator to function correctly.
                  */
                 start = pgdat->node_start_pfn & ~(MAX_ORDER_NR_PAGES - 1);
-                end = pgdat->node_start_pfn + pgdat->node_spanned_pages;
+                end = pgdat_end_pfn(pgdat);
                 end = ALIGN(end, MAX_ORDER_NR_PAGES);
                 size =  (end - start) * sizeof(struct page);
                 map = alloc_remap(pgdat->node_id, size);
@@ -5928,8 +5926,7 @@ void set_pageblock_flags_group(struct page *page, unsigned long flags,
         pfn = page_to_pfn(page);
         bitmap = get_pageblock_bitmap(zone, pfn);
         bitidx = pfn_to_bitidx(zone, pfn);
-        VM_BUG_ON(pfn < zone->zone_start_pfn);
-        VM_BUG_ON(pfn >= zone->zone_start_pfn + zone->spanned_pages);
+        VM_BUG_ON(!zone_spans_pfn(zone, pfn));
 
         for (; start_bitidx <= end_bitidx; start_bitidx++, value <<= 1)
                 if (flags & value)
@@ -6027,8 +6024,7 @@ bool is_pageblock_removable_nolock(struct page *page)
 
         zone = page_zone(page);
         pfn = page_to_pfn(page);
-        if (zone->zone_start_pfn > pfn ||
-                        zone->zone_start_pfn + zone->spanned_pages <= pfn)
+        if (!zone_spans_pfn(zone, pfn))
                 return false;
 
         return !has_unmovable_pages(zone, page, 0, true);