mm, compaction: wrap calculating first and last pfn of pageblock

Compaction code has accumulated numerous instances of manual
calculations of the first (inclusive) and last (exclusive) pfn of a
pageblock (or a smaller block of given order), given a pfn within the
pageblock.

Wrap these calculations by introducing pageblock_start_pfn(pfn) and
pageblock_end_pfn(pfn) macros.

[vbabka@suse.cz: fix crash in get_pfnblock_flags_mask() from isolate_freepages():]
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Rik van Riel <riel@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 19 insertions, 14 deletions

diff --git a/mm/compaction.c b/mm/compaction.c
index 8fa254043801..017a1a1963cb 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -42,6 +42,11 @@ static inline void count_compact_events(enum vm_event_item item, long delta)
 #define CREATE_TRACE_POINTS
 #include <trace/events/compaction.h>
 
+#define block_start_pfn(pfn, order)     round_down(pfn, 1UL << (order))
+#define block_end_pfn(pfn, order)       ALIGN((pfn) + 1, 1UL << (order))
+#define pageblock_start_pfn(pfn)        block_start_pfn(pfn, pageblock_order)
+#define pageblock_end_pfn(pfn)          block_end_pfn(pfn, pageblock_order)
+
 static unsigned long release_freepages(struct list_head *freelist)
 {
         struct page *page, *next;
@@ -161,7 +166,7 @@ static void reset_cached_positions(struct zone *zone)
         zone->compact_cached_migrate_pfn[0] = zone->zone_start_pfn;
         zone->compact_cached_migrate_pfn[1] = zone->zone_start_pfn;
         zone->compact_cached_free_pfn =
-                        round_down(zone_end_pfn(zone) - 1, pageblock_nr_pages);
+                                pageblock_start_pfn(zone_end_pfn(zone) - 1);
 }
 
 /*
@@ -519,10 +524,10 @@ isolate_freepages_range(struct compact_control *cc,
         LIST_HEAD(freelist);
 
         pfn = start_pfn;
-        block_start_pfn = pfn & ~(pageblock_nr_pages - 1);
+        block_start_pfn = pageblock_start_pfn(pfn);
         if (block_start_pfn < cc->zone->zone_start_pfn)
                 block_start_pfn = cc->zone->zone_start_pfn;
-        block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
+        block_end_pfn = pageblock_end_pfn(pfn);
 
         for (; pfn < end_pfn; pfn += isolated,
                                 block_start_pfn = block_end_pfn,
@@ -538,8 +543,8 @@ isolate_freepages_range(struct compact_control *cc,
                  * scanning range to right one.
                  */
                 if (pfn >= block_end_pfn) {
-                        block_start_pfn = pfn & ~(pageblock_nr_pages - 1);
-                        block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
+                        block_start_pfn = pageblock_start_pfn(pfn);
+                        block_end_pfn = pageblock_end_pfn(pfn);
                         block_end_pfn = min(block_end_pfn, end_pfn);
                 }
 
@@ -834,10 +839,10 @@ isolate_migratepages_range(struct compact_control *cc, unsigned long start_pfn,
 
         /* Scan block by block. First and last block may be incomplete */
         pfn = start_pfn;
-        block_start_pfn = pfn & ~(pageblock_nr_pages - 1);
+        block_start_pfn = pageblock_start_pfn(pfn);
         if (block_start_pfn < cc->zone->zone_start_pfn)
                 block_start_pfn = cc->zone->zone_start_pfn;
-        block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
+        block_end_pfn = pageblock_end_pfn(pfn);
 
         for (; pfn < end_pfn; pfn = block_end_pfn,
                                 block_start_pfn = block_end_pfn,
@@ -924,10 +929,10 @@ static void isolate_freepages(struct compact_control *cc)
          * is using.
          */
         isolate_start_pfn = cc->free_pfn;
-        block_start_pfn = cc->free_pfn & ~(pageblock_nr_pages-1);
+        block_start_pfn = pageblock_start_pfn(cc->free_pfn);
         block_end_pfn = min(block_start_pfn + pageblock_nr_pages,
                                                 zone_end_pfn(zone));
-        low_pfn = ALIGN(cc->migrate_pfn + 1, pageblock_nr_pages);
+        low_pfn = pageblock_end_pfn(cc->migrate_pfn);
 
         /*
          * Isolate free pages until enough are available to migrate the
@@ -1081,12 +1086,12 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
          * initialized by compact_zone()
          */
         low_pfn = cc->migrate_pfn;
-        block_start_pfn = cc->migrate_pfn & ~(pageblock_nr_pages - 1);
+        block_start_pfn = pageblock_start_pfn(low_pfn);
         if (block_start_pfn < zone->zone_start_pfn)
                 block_start_pfn = zone->zone_start_pfn;
 
         /* Only scan within a pageblock boundary */
-        block_end_pfn = ALIGN(low_pfn + 1, pageblock_nr_pages);
+        block_end_pfn = pageblock_end_pfn(low_pfn);
 
         /*
          * Iterate over whole pageblocks until we find the first suitable.
@@ -1343,7 +1348,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
         cc->migrate_pfn = zone->compact_cached_migrate_pfn[sync];
         cc->free_pfn = zone->compact_cached_free_pfn;
         if (cc->free_pfn < start_pfn || cc->free_pfn >= end_pfn) {
-                cc->free_pfn = round_down(end_pfn - 1, pageblock_nr_pages);
+                cc->free_pfn = pageblock_start_pfn(end_pfn - 1);
                 zone->compact_cached_free_pfn = cc->free_pfn;
         }
         if (cc->migrate_pfn < start_pfn || cc->migrate_pfn >= end_pfn) {
@@ -1411,7 +1416,7 @@ check_drain:
                 if (cc->order > 0 && cc->last_migrated_pfn) {
                         int cpu;
                         unsigned long current_block_start =
-                                cc->migrate_pfn & ~((1UL << cc->order) - 1);
+                                block_start_pfn(cc->migrate_pfn, cc->order);
 
                         if (cc->last_migrated_pfn < current_block_start) {
                                 cpu = get_cpu();
@@ -1436,7 +1441,7 @@ out:
                 cc->nr_freepages = 0;
                 VM_BUG_ON(free_pfn == 0);
                 /* The cached pfn is always the first in a pageblock */
-                free_pfn &= ~(pageblock_nr_pages-1);
+                free_pfn = pageblock_start_pfn(free_pfn);
                 /*
                  * Only go back, not forward. The cached pfn might have been
                  * already reset to zone end in compact_finished()