mm/compaction: improve comment of is_via_compact_memory

We do proactive compaction with order == -1 via
1. /proc/sys/vm/compact_memory
2. /sys/devices/system/node/nodex/compact
3. /proc/sys/vm/compaction_proactiveness
Add missed situation in which order == -1.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Kemeng Shi <[email protected]>
Reviewed-by: Baolin Wang <[email protected]>
Acked-by: Mel Gorman <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

diff --git a/mm/compaction.c b/mm/compaction.c
index c377d78e0f1568e78d4761aa835bd3aaa44b3f9b..ff3426a0d9c54a7f1194f0c167d43b333de41b34 100644 (file)
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -2065,8 +2065,10 @@ static isolate_migrate_t isolate_migratepages(struct compact_control *cc)
 }
 
 /*
- * order == -1 is expected when compacting via
- * /proc/sys/vm/compact_memory
+ * order == -1 is expected when compacting proactively via
+ * 1. /proc/sys/vm/compact_memory
+ * 2. /sys/devices/system/node/nodex/compact
+ * 3. /proc/sys/vm/compaction_proactiveness
  */
 static inline bool is_via_compact_memory(int order)
 {