thp: use compaction in kswapd for GFP_ATOMIC order > 0

This takes advantage of memory compaction to properly generate pages of
order > 0 if regular page reclaim fails and priority level becomes more
severe and we don't reach the proper watermarks.

Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 8 insertions, 3 deletions

diff --git a/include/linux/compaction.h b/include/linux/compaction.h
index 72cba4034785..dfa2ed4c0d26 100644
--- a/include/linux/compaction.h
+++ b/include/linux/compaction.h
@@ -11,6 +11,9 @@
 /* The full zone was compacted */
 #define COMPACT_COMPLETE        3
 
+#define COMPACT_MODE_DIRECT_RECLAIM     0
+#define COMPACT_MODE_KSWAPD             1
+
 #ifdef CONFIG_COMPACTION
 extern int sysctl_compact_memory;
 extern int sysctl_compaction_handler(struct ctl_table *table, int write,
@@ -25,7 +28,8 @@ extern unsigned long try_to_compact_pages(struct zonelist *zonelist,
                         bool sync);
 extern unsigned long compaction_suitable(struct zone *zone, int order);
 extern unsigned long compact_zone_order(struct zone *zone, int order,
-                                                gfp_t gfp_mask, bool sync);
+                                        gfp_t gfp_mask, bool sync,
+                                        int compact_mode);
 
 /* Do not skip compaction more than 64 times */
 #define COMPACT_MAX_DEFER_SHIFT 6
@@ -70,9 +74,10 @@ static inline unsigned long compaction_suitable(struct zone *zone, int order)
 }
 
 static inline unsigned long compact_zone_order(struct zone *zone, int order,
-                                                gfp_t gfp_mask, bool sync)
+                                               gfp_t gfp_mask, bool sync,
+                                               int compact_mode)
 {
-        return 0;
+        return COMPACT_CONTINUE;
 }
 
 static inline void defer_compaction(struct zone *zone)