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);