mm/compaction.c: add an is_via_compact_memory() helper

Introduce is_via_compact_memory() helper indicating compacting via
/proc/sys/vm/compact_memory to improve readability.

To catch this situation in __compaction_suitable, use order as parameter
directly instead of using struct compact_control.

This patch has no functional changes.

Signed-off-by: Yaowei Bai <bywxiaobai@163.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Acked-by: David Rientjes <rientjes@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 c5c627a..a8e6593 100644 (file)
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1197,6 +1197,15 @@ static isolate_migrate_t isolate_migratepages(struct zone *zone,
        return cc->nr_migratepages ? ISOLATE_SUCCESS : ISOLATE_NONE;
 }
 
+/*
+ * order == -1 is expected when compacting via
+ * /proc/sys/vm/compact_memory
+ */
+static inline bool is_via_compact_memory(int order)
+{
+       return order == -1;
+}
+
 static int __compact_finished(struct zone *zone, struct compact_control *cc,
                            const int migratetype)
 {
@@ -1223,11 +1232,7 @@ static int __compact_finished(struct zone *zone, struct compact_control *cc,
                return COMPACT_COMPLETE;
        }
 
-       /*
-        * order == -1 is expected when compacting via
-        * /proc/sys/vm/compact_memory
-        */
-       if (cc->order == -1)
+       if (is_via_compact_memory(cc->order))
                return COMPACT_CONTINUE;
 
        /* Compaction run is not finished if the watermark is not met */
@@ -1290,11 +1295,7 @@ static unsigned long __compaction_suitable(struct zone *zone, int order,
        int fragindex;
        unsigned long watermark;
 
-       /*
-        * order == -1 is expected when compacting via
-        * /proc/sys/vm/compact_memory
-        */
-       if (order == -1)
+       if (is_via_compact_memory(order))
                return COMPACT_CONTINUE;
 
        watermark = low_wmark_pages(zone);
@@ -1658,10 +1659,11 @@ static void __compact_pgdat(pg_data_t *pgdat, struct compact_control *cc)
                 * this makes sure we compact the whole zone regardless of
                 * cached scanner positions.
                 */
-               if (cc->order == -1)
+               if (is_via_compact_memory(cc->order))
                        __reset_isolation_suitable(zone);
 
-               if (cc->order == -1 || !compaction_deferred(zone, cc->order))
+               if (is_via_compact_memory(cc->order) ||
+                               !compaction_deferred(zone, cc->order))
                        compact_zone(zone, cc);
 
                if (cc->order > 0) {