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>

diff --git a/mm/compaction.c b/mm/compaction.c
index 8fa2540..017a1a1 100644 (file)
--- 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()