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>

6 files changed, 32 insertions, 27 deletions

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 6c80d0ac14dd..34343f51e211 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -527,6 +527,16 @@ static inline int zone_is_oom_locked(const struct zone *zone)
         return test_bit(ZONE_OOM_LOCKED, &zone->flags);
 }
 
+static inline unsigned zone_end_pfn(const struct zone *zone)
+{
+        return zone->zone_start_pfn + zone->spanned_pages;
+}
+
+static inline bool zone_spans_pfn(const struct zone *zone, unsigned long pfn)
+{
+        return zone->zone_start_pfn <= pfn && pfn < zone_end_pfn(zone);
+}
+
 /*
  * The "priority" of VM scanning is how much of the queues we will scan in one
  * go. A value of 12 for DEF_PRIORITY implies that we will scan 1/4096th of the
diff --git a/mm/compaction.c b/mm/compaction.c
index 25e75e3e2ac6..05ccb4cc0bdb 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -86,7 +86,7 @@ static inline bool isolation_suitable(struct compact_control *cc,
 static void __reset_isolation_suitable(struct zone *zone)
 {
         unsigned long start_pfn = zone->zone_start_pfn;
-        unsigned long end_pfn = zone->zone_start_pfn + zone->spanned_pages;
+        unsigned long end_pfn = zone_end_pfn(zone);
         unsigned long pfn;
 
         zone->compact_cached_migrate_pfn = start_pfn;
@@ -647,7 +647,7 @@ static void isolate_freepages(struct zone *zone,
                                 struct compact_control *cc)
 {
         struct page *page;
-        unsigned long high_pfn, low_pfn, pfn, zone_end_pfn, end_pfn;
+        unsigned long high_pfn, low_pfn, pfn, z_end_pfn, end_pfn;
         int nr_freepages = cc->nr_freepages;
         struct list_head *freelist = &cc->freepages;
 
@@ -666,7 +666,7 @@ static void isolate_freepages(struct zone *zone,
          */
         high_pfn = min(low_pfn, pfn);
 
-        zone_end_pfn = zone->zone_start_pfn + zone->spanned_pages;
+        z_end_pfn = zone_end_pfn(zone);
 
         /*
          * Isolate free pages until enough are available to migrate the
@@ -709,7 +709,7 @@ static void isolate_freepages(struct zone *zone,
                  * only scans within a pageblock
                  */
                 end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
-                end_pfn = min(end_pfn, zone_end_pfn);
+                end_pfn = min(end_pfn, z_end_pfn);
                 isolated = isolate_freepages_block(cc, pfn, end_pfn,
                                                    freelist, false);
                 nr_freepages += isolated;
@@ -923,7 +923,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
 {
         int ret;
         unsigned long start_pfn = zone->zone_start_pfn;
-        unsigned long end_pfn = zone->zone_start_pfn + zone->spanned_pages;
+        unsigned long end_pfn = zone_end_pfn(zone);
 
         ret = compaction_suitable(zone, cc->order);
         switch (ret) {
diff --git a/mm/kmemleak.c b/mm/kmemleak.c
index 752a705c77c2..83dd5fbf5e60 100644
--- a/mm/kmemleak.c
+++ b/mm/kmemleak.c
@@ -1300,9 +1300,8 @@ static void kmemleak_scan(void)
          */
         lock_memory_hotplug();
         for_each_online_node(i) {
-                pg_data_t *pgdat = NODE_DATA(i);
-                unsigned long start_pfn = pgdat->node_start_pfn;
-                unsigned long end_pfn = start_pfn + pgdat->node_spanned_pages;
+                unsigned long start_pfn = node_start_pfn(i);
+                unsigned long end_pfn = node_end_pfn(i);
                 unsigned long pfn;
 
                 for (pfn = start_pfn; pfn < end_pfn; pfn++) {
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index dda1ca695a08..8b3235eedf3d 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -299,7 +299,7 @@ static int __meminit move_pfn_range_left(struct zone *z1, struct zone *z2,
         pgdat_resize_lock(z1->zone_pgdat, &flags);
 
         /* can't move pfns which are higher than @z2 */
-        if (end_pfn > z2->zone_start_pfn + z2->spanned_pages)
+        if (end_pfn > zone_end_pfn(z2))
                 goto out_fail;
         /* the move out part mast at the left most of @z2 */
         if (start_pfn > z2->zone_start_pfn)
@@ -315,7 +315,7 @@ static int __meminit move_pfn_range_left(struct zone *z1, struct zone *z2,
                 z1_start_pfn = start_pfn;
 
         resize_zone(z1, z1_start_pfn, end_pfn);
-        resize_zone(z2, end_pfn, z2->zone_start_pfn + z2->spanned_pages);
+        resize_zone(z2, end_pfn, zone_end_pfn(z2));
 
         pgdat_resize_unlock(z1->zone_pgdat, &flags);
 
@@ -347,15 +347,15 @@ static int __meminit move_pfn_range_right(struct zone *z1, struct zone *z2,
         if (z1->zone_start_pfn > start_pfn)
                 goto out_fail;
         /* the move out part mast at the right most of @z1 */
-        if (z1->zone_start_pfn + z1->spanned_pages >  end_pfn)
+        if (zone_end_pfn(z1) >  end_pfn)
                 goto out_fail;
         /* must included/overlap */
-        if (start_pfn >= z1->zone_start_pfn + z1->spanned_pages)
+        if (start_pfn >= zone_end_pfn(z1))
                 goto out_fail;
 
         /* use end_pfn for z2's end_pfn if z2 is empty */
         if (z2->spanned_pages)
-                z2_end_pfn = z2->zone_start_pfn + z2->spanned_pages;
+                z2_end_pfn = zone_end_pfn(z2);
         else
                 z2_end_pfn = end_pfn;
 
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);
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 57f02fd1768b..e1d8ed172c42 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -891,7 +891,7 @@ static void pagetypeinfo_showblockcount_print(struct seq_file *m,
         int mtype;
         unsigned long pfn;
         unsigned long start_pfn = zone->zone_start_pfn;
-        unsigned long end_pfn = start_pfn + zone->spanned_pages;
+        unsigned long end_pfn = zone_end_pfn(zone);
         unsigned long count[MIGRATE_TYPES] = { 0, };
 
         for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {