1 files changed, 87 insertions, 15 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 3464312bde07..10ebd74a423c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -32,6 +32,7 @@
 #include <linux/topology.h>
 #include <linux/cpu.h>
 #include <linux/cpuset.h>
+#include <linux/compaction.h>
 #include <linux/notifier.h>
 #include <linux/rwsem.h>
 #include <linux/delay.h>
@@ -59,12 +60,15 @@
  * LUMPY_MODE_CONTIGRECLAIM: For high-order allocations, take a reference
  *                      page from the LRU and reclaim all pages within a
  *                      naturally aligned range
+ * LUMPY_MODE_COMPACTION: For high-order allocations, reclaim a number of
+ *                      order-0 pages and then compact the zone
  */
 typedef unsigned __bitwise__ lumpy_mode;
 #define LUMPY_MODE_SINGLE               ((__force lumpy_mode)0x01u)
 #define LUMPY_MODE_ASYNC                ((__force lumpy_mode)0x02u)
 #define LUMPY_MODE_SYNC                 ((__force lumpy_mode)0x04u)
 #define LUMPY_MODE_CONTIGRECLAIM        ((__force lumpy_mode)0x08u)
+#define LUMPY_MODE_COMPACTION           ((__force lumpy_mode)0x10u)
 
 struct scan_control {
         /* Incremented by the number of inactive pages that were scanned */
@@ -286,18 +290,20 @@ static void set_lumpy_reclaim_mode(int priority, struct scan_control *sc,
         lumpy_mode syncmode = sync ? LUMPY_MODE_SYNC : LUMPY_MODE_ASYNC;
 
         /*
-         * Some reclaim have alredy been failed. No worth to try synchronous
-         * lumpy reclaim.
+         * Initially assume we are entering either lumpy reclaim or
+         * reclaim/compaction.Depending on the order, we will either set the
+         * sync mode or just reclaim order-0 pages later.
          */
-        if (sync && sc->lumpy_reclaim_mode & LUMPY_MODE_SINGLE)
-                return;
+        if (COMPACTION_BUILD)
+                sc->lumpy_reclaim_mode = LUMPY_MODE_COMPACTION;
+        else
+                sc->lumpy_reclaim_mode = LUMPY_MODE_CONTIGRECLAIM;
 
         /*
-         * If we need a large contiguous chunk of memory, or have
-         * trouble getting a small set of contiguous pages, we
-         * will reclaim both active and inactive pages.
+         * Avoid using lumpy reclaim or reclaim/compaction if possible by
+         * restricting when its set to either costly allocations or when
+         * under memory pressure
          */
-        sc->lumpy_reclaim_mode = LUMPY_MODE_CONTIGRECLAIM;
         if (sc->order > PAGE_ALLOC_COSTLY_ORDER)
                 sc->lumpy_reclaim_mode |= syncmode;
         else if (sc->order && priority < DEF_PRIORITY - 2)
@@ -1385,8 +1391,8 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
         if (scanning_global_lru(sc)) {
                 nr_taken = isolate_pages_global(nr_to_scan,
                         &page_list, &nr_scanned, sc->order,
-                        sc->lumpy_reclaim_mode & LUMPY_MODE_SINGLE ?
-                                        ISOLATE_INACTIVE : ISOLATE_BOTH,
+                        sc->lumpy_reclaim_mode & LUMPY_MODE_CONTIGRECLAIM ?
+                                        ISOLATE_BOTH : ISOLATE_INACTIVE,
                         zone, 0, file);
                 zone->pages_scanned += nr_scanned;
                 if (current_is_kswapd())
@@ -1398,8 +1404,8 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
         } else {
                 nr_taken = mem_cgroup_isolate_pages(nr_to_scan,
                         &page_list, &nr_scanned, sc->order,
-                        sc->lumpy_reclaim_mode & LUMPY_MODE_SINGLE ?
-                                        ISOLATE_INACTIVE : ISOLATE_BOTH,
+                        sc->lumpy_reclaim_mode & LUMPY_MODE_CONTIGRECLAIM ?
+                                        ISOLATE_BOTH : ISOLATE_INACTIVE,
                         zone, sc->mem_cgroup,
                         0, file);
                 /*
@@ -1815,6 +1821,57 @@ out:
 }
 
 /*
+ * Reclaim/compaction depends on a number of pages being freed. To avoid
+ * disruption to the system, a small number of order-0 pages continue to be
+ * rotated and reclaimed in the normal fashion. However, by the time we get
+ * back to the allocator and call try_to_compact_zone(), we ensure that
+ * there are enough free pages for it to be likely successful
+ */
+static inline bool should_continue_reclaim(struct zone *zone,
+                                        unsigned long nr_reclaimed,
+                                        unsigned long nr_scanned,
+                                        struct scan_control *sc)
+{
+        unsigned long pages_for_compaction;
+        unsigned long inactive_lru_pages;
+
+        /* If not in reclaim/compaction mode, stop */
+        if (!(sc->lumpy_reclaim_mode & LUMPY_MODE_COMPACTION))
+                return false;
+
+        /*
+         * If we failed to reclaim and have scanned the full list, stop.
+         * NOTE: Checking just nr_reclaimed would exit reclaim/compaction far
+         *       faster but obviously would be less likely to succeed
+         *       allocation. If this is desirable, use GFP_REPEAT to decide
+         *       if both reclaimed and scanned should be checked or just
+         *       reclaimed
+         */
+        if (!nr_reclaimed && !nr_scanned)
+                return false;
+
+        /*
+         * If we have not reclaimed enough pages for compaction and the
+         * inactive lists are large enough, continue reclaiming
+         */
+        pages_for_compaction = (2UL << sc->order);
+        inactive_lru_pages = zone_nr_lru_pages(zone, sc, LRU_INACTIVE_ANON) +
+                                zone_nr_lru_pages(zone, sc, LRU_INACTIVE_FILE);
+        if (sc->nr_reclaimed < pages_for_compaction &&
+                        inactive_lru_pages > pages_for_compaction)
+                return true;
+
+        /* If compaction would go ahead or the allocation would succeed, stop */
+        switch (compaction_suitable(zone, sc->order)) {
+        case COMPACT_PARTIAL:
+        case COMPACT_CONTINUE:
+                return false;
+        default:
+                return true;
+        }
+}
+
+/*
  * This is a basic per-zone page freer.  Used by both kswapd and direct reclaim.
  */
 static void shrink_zone(int priority, struct zone *zone,
@@ -1823,9 +1880,12 @@ static void shrink_zone(int priority, struct zone *zone,
         unsigned long nr[NR_LRU_LISTS];
         unsigned long nr_to_scan;
         enum lru_list l;
-        unsigned long nr_reclaimed = sc->nr_reclaimed;
+        unsigned long nr_reclaimed;
         unsigned long nr_to_reclaim = sc->nr_to_reclaim;
+        unsigned long nr_scanned = sc->nr_scanned;
 
+restart:
+        nr_reclaimed = 0;
         get_scan_count(zone, sc, nr, priority);
 
         while (nr[LRU_INACTIVE_ANON] || nr[LRU_ACTIVE_FILE] ||
@@ -1851,8 +1911,7 @@ static void shrink_zone(int priority, struct zone *zone,
                 if (nr_reclaimed >= nr_to_reclaim && priority < DEF_PRIORITY)
                         break;
         }
-
-        sc->nr_reclaimed = nr_reclaimed;
+        sc->nr_reclaimed += nr_reclaimed;
 
         /*
          * Even if we did not try to evict anon pages at all, we want to
@@ -1861,6 +1920,11 @@ static void shrink_zone(int priority, struct zone *zone,
         if (inactive_anon_is_low(zone, sc))
                 shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);
 
+        /* reclaim/compaction might need reclaim to continue */
+        if (should_continue_reclaim(zone, nr_reclaimed,
+                                        sc->nr_scanned - nr_scanned, sc))
+                goto restart;
+
         throttle_vm_writeout(sc->gfp_mask);
 }
 
@@ -2307,6 +2371,14 @@ loop_again:
                             total_scanned > sc.nr_reclaimed + sc.nr_reclaimed / 2)
                                 sc.may_writepage = 1;
 
+                        /*
+                         * Compact the zone for higher orders to reduce
+                         * latencies for higher-order allocations that
+                         * would ordinarily call try_to_compact_pages()
+                         */
+                        if (sc.order > PAGE_ALLOC_COSTLY_ORDER)
+                                compact_zone_order(zone, sc.order, sc.gfp_mask);
+
                         if (!zone_watermark_ok_safe(zone, order,
                                         high_wmark_pages(zone), end_zone, 0)) {
                                 all_zones_ok = 0;