checkpatch: yet another commit id improvement
[cascardo/linux.git] / mm / vmscan.c
index 766b36b..374d95d 100644 (file)
@@ -203,9 +203,11 @@ unsigned long zone_reclaimable_pages(struct zone *zone)
 {
        unsigned long nr;
 
-       nr = zone_page_state_snapshot(zone, NR_ZONE_LRU_FILE);
+       nr = zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_FILE) +
+               zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_FILE);
        if (get_nr_swap_pages() > 0)
-               nr += zone_page_state_snapshot(zone, NR_ZONE_LRU_ANON);
+               nr += zone_page_state_snapshot(zone, NR_ZONE_INACTIVE_ANON) +
+                       zone_page_state_snapshot(zone, NR_ZONE_ACTIVE_ANON);
 
        return nr;
 }
@@ -612,7 +614,7 @@ static pageout_t pageout(struct page *page, struct address_space *mapping,
                        ClearPageReclaim(page);
                }
                trace_mm_vmscan_writepage(page);
-               inc_zone_page_state(page, NR_VMSCAN_WRITE);
+               inc_node_page_state(page, NR_VMSCAN_WRITE);
                return PAGE_SUCCESS;
        }
 
@@ -1117,7 +1119,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
                                 * except we already have the page isolated
                                 * and know it's dirty
                                 */
-                               inc_zone_page_state(page, NR_VMSCAN_IMMEDIATE);
+                               inc_node_page_state(page, NR_VMSCAN_IMMEDIATE);
                                SetPageReclaim(page);
 
                                goto keep_locked;
@@ -1366,6 +1368,29 @@ int __isolate_lru_page(struct page *page, isolate_mode_t mode)
        return ret;
 }
 
+
+/*
+ * Update LRU sizes after isolating pages. The LRU size updates must
+ * be complete before mem_cgroup_update_lru_size due to a santity check.
+ */
+static __always_inline void update_lru_sizes(struct lruvec *lruvec,
+                       enum lru_list lru, unsigned long *nr_zone_taken,
+                       unsigned long nr_taken)
+{
+       int zid;
+
+       for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+               if (!nr_zone_taken[zid])
+                       continue;
+
+               __update_lru_size(lruvec, lru, zid, -nr_zone_taken[zid]);
+       }
+
+#ifdef CONFIG_MEMCG
+       mem_cgroup_update_lru_size(lruvec, lru, -nr_taken);
+#endif
+}
+
 /*
  * zone_lru_lock is heavily contended.  Some of the functions that
  * shrink the lists perform better by taking out a batch of pages
@@ -1394,11 +1419,12 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
        struct list_head *src = &lruvec->lists[lru];
        unsigned long nr_taken = 0;
        unsigned long nr_zone_taken[MAX_NR_ZONES] = { 0 };
+       unsigned long nr_skipped[MAX_NR_ZONES] = { 0, };
        unsigned long scan, nr_pages;
        LIST_HEAD(pages_skipped);
 
        for (scan = 0; scan < nr_to_scan && nr_taken < nr_to_scan &&
-                                       !list_empty(src); scan++) {
+                                       !list_empty(src);) {
                struct page *page;
 
                page = lru_to_page(src);
@@ -1408,9 +1434,16 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 
                if (page_zonenum(page) > sc->reclaim_idx) {
                        list_move(&page->lru, &pages_skipped);
+                       nr_skipped[page_zonenum(page)]++;
                        continue;
                }
 
+               /*
+                * Account for scanned and skipped separetly to avoid the pgdat
+                * being prematurely marked unreclaimable by pgdat_reclaimable.
+                */
+               scan++;
+
                switch (__isolate_lru_page(page, mode)) {
                case 0:
                        nr_pages = hpage_nr_pages(page);
@@ -1436,18 +1469,31 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
         * scanning would soon rescan the same pages to skip and put the
         * system at risk of premature OOM.
         */
-       if (!list_empty(&pages_skipped))
+       if (!list_empty(&pages_skipped)) {
+               int zid;
+               unsigned long total_skipped = 0;
+
+               for (zid = 0; zid < MAX_NR_ZONES; zid++) {
+                       if (!nr_skipped[zid])
+                               continue;
+
+                       __count_zid_vm_events(PGSCAN_SKIP, zid, nr_skipped[zid]);
+                       total_skipped += nr_skipped[zid];
+               }
+
+               /*
+                * Account skipped pages as a partial scan as the pgdat may be
+                * close to unreclaimable. If the LRU list is empty, account
+                * skipped pages as a full scan.
+                */
+               scan += list_empty(src) ? total_skipped : total_skipped >> 2;
+
                list_splice(&pages_skipped, src);
+       }
        *nr_scanned = scan;
-       trace_mm_vmscan_lru_isolate(sc->order, nr_to_scan, scan,
+       trace_mm_vmscan_lru_isolate(sc->reclaim_idx, sc->order, nr_to_scan, scan,
                                    nr_taken, mode, is_file_lru(lru));
-       for (scan = 0; scan < MAX_NR_ZONES; scan++) {
-               nr_pages = nr_zone_taken[scan];
-               if (!nr_pages)
-                       continue;
-
-               update_lru_size(lruvec, lru, scan, -nr_pages);
-       }
+       update_lru_sizes(lruvec, lru, nr_zone_taken, nr_taken);
        return nr_taken;
 }
 
@@ -1606,6 +1652,30 @@ static int current_may_throttle(void)
                bdi_write_congested(current->backing_dev_info);
 }
 
+static bool inactive_reclaimable_pages(struct lruvec *lruvec,
+                               struct scan_control *sc, enum lru_list lru)
+{
+       int zid;
+       struct zone *zone;
+       int file = is_file_lru(lru);
+       struct pglist_data *pgdat = lruvec_pgdat(lruvec);
+
+       if (!global_reclaim(sc))
+               return true;
+
+       for (zid = sc->reclaim_idx; zid >= 0; zid--) {
+               zone = &pgdat->node_zones[zid];
+               if (!populated_zone(zone))
+                       continue;
+
+               if (zone_page_state_snapshot(zone, NR_ZONE_LRU_BASE +
+                               LRU_FILE * file) >= SWAP_CLUSTER_MAX)
+                       return true;
+       }
+
+       return false;
+}
+
 /*
  * shrink_inactive_list() is a helper for shrink_node().  It returns the number
  * of reclaimed pages
@@ -1628,6 +1698,9 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
        struct pglist_data *pgdat = lruvec_pgdat(lruvec);
        struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
 
+       if (!inactive_reclaimable_pages(lruvec, sc, lru))
+               return 0;
+
        while (unlikely(too_many_isolated(pgdat, file, sc))) {
                congestion_wait(BLK_RW_ASYNC, HZ/10);
 
@@ -1934,12 +2007,15 @@ static void shrink_active_list(unsigned long nr_to_scan,
  *    1TB     101        10GB
  *   10TB     320        32GB
  */
-static bool inactive_list_is_low(struct lruvec *lruvec, bool file)
+static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
+                                               struct scan_control *sc)
 {
        unsigned long inactive_ratio;
        unsigned long inactive;
        unsigned long active;
        unsigned long gb;
+       struct pglist_data *pgdat = lruvec_pgdat(lruvec);
+       int zid;
 
        /*
         * If we don't have swap space, anonymous page deactivation
@@ -1951,6 +2027,27 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file)
        inactive = lruvec_lru_size(lruvec, file * LRU_FILE);
        active = lruvec_lru_size(lruvec, file * LRU_FILE + LRU_ACTIVE);
 
+       /*
+        * For zone-constrained allocations, it is necessary to check if
+        * deactivations are required for lowmem to be reclaimed. This
+        * calculates the inactive/active pages available in eligible zones.
+        */
+       for (zid = sc->reclaim_idx + 1; zid < MAX_NR_ZONES; zid++) {
+               struct zone *zone = &pgdat->node_zones[zid];
+               unsigned long inactive_zone, active_zone;
+
+               if (!populated_zone(zone))
+                       continue;
+
+               inactive_zone = zone_page_state(zone,
+                               NR_ZONE_LRU_BASE + (file * LRU_FILE));
+               active_zone = zone_page_state(zone,
+                               NR_ZONE_LRU_BASE + (file * LRU_FILE) + LRU_ACTIVE);
+
+               inactive -= min(inactive, inactive_zone);
+               active -= min(active, active_zone);
+       }
+
        gb = (inactive + active) >> (30 - PAGE_SHIFT);
        if (gb)
                inactive_ratio = int_sqrt(10 * gb);
@@ -1964,7 +2061,7 @@ static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
                                 struct lruvec *lruvec, struct scan_control *sc)
 {
        if (is_active_lru(lru)) {
-               if (inactive_list_is_low(lruvec, is_file_lru(lru)))
+               if (inactive_list_is_low(lruvec, is_file_lru(lru), sc))
                        shrink_active_list(nr_to_scan, lruvec, sc, lru);
                return 0;
        }
@@ -2095,7 +2192,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
         * lruvec even if it has plenty of old anonymous pages unless the
         * system is under heavy pressure.
         */
-       if (!inactive_list_is_low(lruvec, true) &&
+       if (!inactive_list_is_low(lruvec, true, sc) &&
            lruvec_lru_size(lruvec, LRU_INACTIVE_FILE) >> sc->priority) {
                scan_balance = SCAN_FILE;
                goto out;
@@ -2224,12 +2321,12 @@ static inline void init_tlb_ubc(void)
 #endif /* CONFIG_ARCH_WANT_BATCHED_UNMAP_TLB_FLUSH */
 
 /*
- * This is a basic per-zone page freer.  Used by both kswapd and direct reclaim.
+ * This is a basic per-node page freer.  Used by both kswapd and direct reclaim.
  */
-static void shrink_zone_memcg(struct zone *zone, struct mem_cgroup *memcg,
+static void shrink_node_memcg(struct pglist_data *pgdat, struct mem_cgroup *memcg,
                              struct scan_control *sc, unsigned long *lru_pages)
 {
-       struct lruvec *lruvec = mem_cgroup_zone_lruvec(zone, memcg);
+       struct lruvec *lruvec = mem_cgroup_lruvec(pgdat, memcg);
        unsigned long nr[NR_LRU_LISTS];
        unsigned long targets[NR_LRU_LISTS];
        unsigned long nr_to_scan;
@@ -2337,7 +2434,7 @@ static void shrink_zone_memcg(struct zone *zone, struct mem_cgroup *memcg,
         * Even if we did not try to evict anon pages at all, we want to
         * rebalance the anon lru active/inactive ratio.
         */
-       if (inactive_list_is_low(lruvec, false))
+       if (inactive_list_is_low(lruvec, false, sc))
                shrink_active_list(SWAP_CLUSTER_MAX, lruvec,
                                   sc, LRU_ACTIVE_ANON);
 
@@ -2362,13 +2459,14 @@ static bool in_reclaim_compaction(struct scan_control *sc)
  * calls try_to_compact_zone() that it will have enough free pages to succeed.
  * It will give up earlier than that if there is difficulty reclaiming pages.
  */
-static inline bool should_continue_reclaim(struct zone *zone,
+static inline bool should_continue_reclaim(struct pglist_data *pgdat,
                                        unsigned long nr_reclaimed,
                                        unsigned long nr_scanned,
                                        struct scan_control *sc)
 {
        unsigned long pages_for_compaction;
        unsigned long inactive_lru_pages;
+       int z;
 
        /* If not in reclaim/compaction mode, stop */
        if (!in_reclaim_compaction(sc))
@@ -2402,38 +2500,44 @@ static inline bool should_continue_reclaim(struct zone *zone,
         * inactive lists are large enough, continue reclaiming
         */
        pages_for_compaction = (2UL << sc->order);
-       inactive_lru_pages = node_page_state(zone->zone_pgdat, NR_INACTIVE_FILE);
+       inactive_lru_pages = node_page_state(pgdat, NR_INACTIVE_FILE);
        if (get_nr_swap_pages() > 0)
-               inactive_lru_pages += node_page_state(zone->zone_pgdat, NR_INACTIVE_ANON);
+               inactive_lru_pages += node_page_state(pgdat, NR_INACTIVE_ANON);
        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, 0, 0)) {
-       case COMPACT_PARTIAL:
-       case COMPACT_CONTINUE:
-               return false;
-       default:
-               return true;
+       for (z = 0; z <= sc->reclaim_idx; z++) {
+               struct zone *zone = &pgdat->node_zones[z];
+               if (!populated_zone(zone))
+                       continue;
+
+               switch (compaction_suitable(zone, sc->order, 0, sc->reclaim_idx)) {
+               case COMPACT_PARTIAL:
+               case COMPACT_CONTINUE:
+                       return false;
+               default:
+                       /* check next zone */
+                       ;
+               }
        }
+       return true;
 }
 
-static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc,
-                       enum zone_type classzone_idx)
+static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
 {
        struct reclaim_state *reclaim_state = current->reclaim_state;
        unsigned long nr_reclaimed, nr_scanned;
        bool reclaimable = false;
-       struct zone *zone = &pgdat->node_zones[classzone_idx];
 
        do {
                struct mem_cgroup *root = sc->target_mem_cgroup;
                struct mem_cgroup_reclaim_cookie reclaim = {
-                       .zone = zone,
+                       .pgdat = pgdat,
                        .priority = sc->priority,
                };
-               unsigned long zone_lru_pages = 0;
+               unsigned long node_lru_pages = 0;
                struct mem_cgroup *memcg;
 
                nr_reclaimed = sc->nr_reclaimed;
@@ -2454,11 +2558,11 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc,
                        reclaimed = sc->nr_reclaimed;
                        scanned = sc->nr_scanned;
 
-                       shrink_zone_memcg(zone, memcg, sc, &lru_pages);
-                       zone_lru_pages += lru_pages;
+                       shrink_node_memcg(pgdat, memcg, sc, &lru_pages);
+                       node_lru_pages += lru_pages;
 
-                       if (!global_reclaim(sc))
-                               shrink_slab(sc->gfp_mask, zone_to_nid(zone),
+                       if (memcg)
+                               shrink_slab(sc->gfp_mask, pgdat->node_id,
                                            memcg, sc->nr_scanned - scanned,
                                            lru_pages);
 
@@ -2470,7 +2574,7 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc,
                        /*
                         * Direct reclaim and kswapd have to scan all memory
                         * cgroups to fulfill the overall scan target for the
-                        * zone.
+                        * node.
                         *
                         * Limit reclaim, on the other hand, only cares about
                         * nr_to_reclaim pages to be reclaimed and it will
@@ -2489,9 +2593,9 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc,
                 * the eligible LRU pages were scanned.
                 */
                if (global_reclaim(sc))
-                       shrink_slab(sc->gfp_mask, zone_to_nid(zone), NULL,
+                       shrink_slab(sc->gfp_mask, pgdat->node_id, NULL,
                                    sc->nr_scanned - nr_scanned,
-                                   zone_lru_pages);
+                                   node_lru_pages);
 
                if (reclaim_state) {
                        sc->nr_reclaimed += reclaim_state->reclaimed_slab;
@@ -2506,7 +2610,7 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc,
                if (sc->nr_reclaimed - nr_reclaimed)
                        reclaimable = true;
 
-       } while (should_continue_reclaim(zone, sc->nr_reclaimed - nr_reclaimed,
+       } while (should_continue_reclaim(pgdat, sc->nr_reclaimed - nr_reclaimed,
                                         sc->nr_scanned - nr_scanned, sc));
 
        return reclaimable;
@@ -2516,9 +2620,9 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc,
  * Returns true if compaction should go ahead for a high-order request, or
  * the high-order allocation would succeed without compaction.
  */
-static inline bool compaction_ready(struct zone *zone, int order, int classzone_idx)
+static inline bool compaction_ready(struct zone *zone, struct scan_control *sc)
 {
-       unsigned long balance_gap, watermark;
+       unsigned long watermark;
        bool watermark_ok;
 
        /*
@@ -2527,23 +2631,21 @@ static inline bool compaction_ready(struct zone *zone, int order, int classzone_
         * there is a buffer of free pages available to give compaction
         * a reasonable chance of completing and allocating the page
         */
-       balance_gap = min(low_wmark_pages(zone), DIV_ROUND_UP(
-                       zone->managed_pages, KSWAPD_ZONE_BALANCE_GAP_RATIO));
-       watermark = high_wmark_pages(zone) + balance_gap + (2UL << order);
-       watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, classzone_idx);
+       watermark = high_wmark_pages(zone) + (2UL << sc->order);
+       watermark_ok = zone_watermark_ok_safe(zone, 0, watermark, sc->reclaim_idx);
 
        /*
         * If compaction is deferred, reclaim up to a point where
         * compaction will have a chance of success when re-enabled
         */
-       if (compaction_deferred(zone, order))
+       if (compaction_deferred(zone, sc->order))
                return watermark_ok;
 
        /*
         * If compaction is not ready to start and allocation is not likely
         * to succeed without it, then keep reclaiming.
         */
-       if (compaction_suitable(zone, order, 0, classzone_idx) == COMPACT_SKIPPED)
+       if (compaction_suitable(zone, sc->order, 0, sc->reclaim_idx) == COMPACT_SKIPPED)
                return false;
 
        return watermark_ok;
@@ -2554,14 +2656,6 @@ static inline bool compaction_ready(struct zone *zone, int order, int classzone_
  * try to reclaim pages from zones which will satisfy the caller's allocation
  * request.
  *
- * We reclaim from a zone even if that zone is over high_wmark_pages(zone).
- * Because:
- * a) The caller may be trying to free *extra* pages to satisfy a higher-order
- *    allocation or
- * b) The target zone may be at high_wmark_pages(zone) but the lower zones
- *    must go *over* high_wmark_pages(zone) to satisfy the `incremental min'
- *    zone defense algorithm.
- *
  * If a zone is deemed to be full of pinned pages then just give it a light
  * scan then give up on it.
  */
@@ -2572,7 +2666,7 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
        unsigned long nr_soft_reclaimed;
        unsigned long nr_soft_scanned;
        gfp_t orig_mask;
-       enum zone_type classzone_idx;
+       pg_data_t *last_pgdat = NULL;
 
        /*
         * If the number of buffer_heads in the machine exceeds the maximum
@@ -2582,25 +2676,11 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
        orig_mask = sc->gfp_mask;
        if (buffer_heads_over_limit) {
                sc->gfp_mask |= __GFP_HIGHMEM;
-               sc->reclaim_idx = classzone_idx = gfp_zone(sc->gfp_mask);
+               sc->reclaim_idx = gfp_zone(sc->gfp_mask);
        }
 
        for_each_zone_zonelist_nodemask(zone, z, zonelist,
                                        sc->reclaim_idx, sc->nodemask) {
-               if (!populated_zone(zone))
-                       continue;
-
-               /*
-                * Note that reclaim_idx does not change as it is the highest
-                * zone reclaimed from which for empty zones is a no-op but
-                * classzone_idx is used by shrink_node to test if the slabs
-                * should be shrunk on a given node.
-                */
-               classzone_idx = sc->reclaim_idx;
-               while (!populated_zone(zone->zone_pgdat->node_zones +
-                                                       classzone_idx))
-                       classzone_idx--;
-
                /*
                 * Take care memory controller reclaiming has small influence
                 * to global LRU.
@@ -2625,12 +2705,20 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
                         */
                        if (IS_ENABLED(CONFIG_COMPACTION) &&
                            sc->order > PAGE_ALLOC_COSTLY_ORDER &&
-                           zonelist_zone_idx(z) <= classzone_idx &&
-                           compaction_ready(zone, sc->order, classzone_idx)) {
+                           compaction_ready(zone, sc)) {
                                sc->compaction_ready = true;
                                continue;
                        }
 
+                       /*
+                        * Shrink each node in the zonelist once. If the
+                        * zonelist is ordered by zone (not the default) then a
+                        * node may be shrunk multiple times but in that case
+                        * the user prefers lower zones being preserved.
+                        */
+                       if (zone->zone_pgdat == last_pgdat)
+                               continue;
+
                        /*
                         * This steals pages from memory cgroups over softlimit
                         * and returns the number of reclaimed pages and
@@ -2638,7 +2726,7 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
                         * and balancing, not for a memcg's limit.
                         */
                        nr_soft_scanned = 0;
-                       nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone,
+                       nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone->zone_pgdat,
                                                sc->order, sc->gfp_mask,
                                                &nr_soft_scanned);
                        sc->nr_reclaimed += nr_soft_reclaimed;
@@ -2646,7 +2734,11 @@ static void shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
                        /* need some check for avoid more shrink_zone() */
                }
 
-               shrink_node(zone->zone_pgdat, sc, classzone_idx);
+               /* See comment about same check for global reclaim above */
+               if (zone->zone_pgdat == last_pgdat)
+                       continue;
+               last_pgdat = zone->zone_pgdat;
+               shrink_node(zone->zone_pgdat, sc);
        }
 
        /*
@@ -2682,7 +2774,7 @@ retry:
        delayacct_freepages_start();
 
        if (global_reclaim(sc))
-               count_vm_event(ALLOCSTALL);
+               __count_zid_vm_events(ALLOCSTALL, sc->reclaim_idx, 1);
 
        do {
                vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup,
@@ -2764,7 +2856,7 @@ static bool pfmemalloc_watermark_ok(pg_data_t *pgdat)
 
        /* kswapd must be awake if processes are being throttled */
        if (!wmark_ok && waitqueue_active(&pgdat->kswapd_wait)) {
-               pgdat->classzone_idx = min(pgdat->classzone_idx,
+               pgdat->kswapd_classzone_idx = min(pgdat->kswapd_classzone_idx,
                                                (enum zone_type)ZONE_NORMAL);
                wake_up_interruptible(&pgdat->kswapd_wait);
        }
@@ -2891,7 +2983,8 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 
        trace_mm_vmscan_direct_reclaim_begin(order,
                                sc.may_writepage,
-                               gfp_mask);
+                               gfp_mask,
+                               sc.reclaim_idx);
 
        nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
 
@@ -2902,9 +2995,9 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 
 #ifdef CONFIG_MEMCG
 
-unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg,
+unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
                                                gfp_t gfp_mask, bool noswap,
-                                               struct zone *zone,
+                                               pg_data_t *pgdat,
                                                unsigned long *nr_scanned)
 {
        struct scan_control sc = {
@@ -2922,16 +3015,17 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg,
 
        trace_mm_vmscan_memcg_softlimit_reclaim_begin(sc.order,
                                                      sc.may_writepage,
-                                                     sc.gfp_mask);
+                                                     sc.gfp_mask,
+                                                     sc.reclaim_idx);
 
        /*
         * NOTE: Although we can get the priority field, using it
         * here is not a good idea, since it limits the pages we can scan.
-        * if we don't reclaim here, the shrink_zone from balance_pgdat
+        * if we don't reclaim here, the shrink_node from balance_pgdat
         * will pick up pages from other mem cgroup's as well. We hack
         * the priority and make it zero.
         */
-       shrink_zone_memcg(zone, memcg, &sc, &lru_pages);
+       shrink_node_memcg(pgdat, memcg, &sc, &lru_pages);
 
        trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
 
@@ -2970,7 +3064,8 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
 
        trace_mm_vmscan_memcg_reclaim_begin(0,
                                            sc.may_writepage,
-                                           sc.gfp_mask);
+                                           sc.gfp_mask,
+                                           sc.reclaim_idx);
 
        nr_reclaimed = do_try_to_free_pages(zonelist, &sc);
 
@@ -2980,7 +3075,8 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
 }
 #endif
 
-static void age_active_anon(struct zone *zone, struct scan_control *sc)
+static void age_active_anon(struct pglist_data *pgdat,
+                               struct scan_control *sc)
 {
        struct mem_cgroup *memcg;
 
@@ -2989,9 +3085,9 @@ static void age_active_anon(struct zone *zone, struct scan_control *sc)
 
        memcg = mem_cgroup_iter(NULL, NULL, NULL);
        do {
-               struct lruvec *lruvec = mem_cgroup_zone_lruvec(zone, memcg);
+               struct lruvec *lruvec = mem_cgroup_lruvec(pgdat, memcg);
 
-               if (inactive_list_is_low(lruvec, false))
+               if (inactive_list_is_low(lruvec, false, sc))
                        shrink_active_list(SWAP_CLUSTER_MAX, lruvec,
                                           sc, LRU_ACTIVE_ANON);
 
@@ -2999,82 +3095,21 @@ static void age_active_anon(struct zone *zone, struct scan_control *sc)
        } while (memcg);
 }
 
-static bool zone_balanced(struct zone *zone, int order, bool highorder,
-                       unsigned long balance_gap, int classzone_idx)
+static bool zone_balanced(struct zone *zone, int order, int classzone_idx)
 {
-       unsigned long mark = high_wmark_pages(zone) + balance_gap;
+       unsigned long mark = high_wmark_pages(zone);
+
+       if (!zone_watermark_ok_safe(zone, order, mark, classzone_idx))
+               return false;
 
        /*
-        * When checking from pgdat_balanced(), kswapd should stop and sleep
-        * when it reaches the high order-0 watermark and let kcompactd take
-        * over. Other callers such as wakeup_kswapd() want to determine the
-        * true high-order watermark.
+        * If any eligible zone is balanced then the node is not considered
+        * to be congested or dirty
         */
-       if (IS_ENABLED(CONFIG_COMPACTION) && !highorder) {
-               mark += (1UL << order);
-               order = 0;
-       }
-
-       return zone_watermark_ok_safe(zone, order, mark, classzone_idx);
-}
-
-/*
- * pgdat_balanced() is used when checking if a node is balanced.
- *
- * For order-0, all zones must be balanced!
- *
- * For high-order allocations only zones that meet watermarks and are in a
- * zone allowed by the callers classzone_idx are added to balanced_pages. The
- * total of balanced pages must be at least 25% of the zones allowed by
- * classzone_idx for the node to be considered balanced. Forcing all zones to
- * be balanced for high orders can cause excessive reclaim when there are
- * imbalanced zones.
- * The choice of 25% is due to
- *   o a 16M DMA zone that is balanced will not balance a zone on any
- *     reasonable sized machine
- *   o On all other machines, the top zone must be at least a reasonable
- *     percentage of the middle zones. For example, on 32-bit x86, highmem
- *     would need to be at least 256M for it to be balance a whole node.
- *     Similarly, on x86-64 the Normal zone would need to be at least 1G
- *     to balance a node on its own. These seemed like reasonable ratios.
- */
-static bool pgdat_balanced(pg_data_t *pgdat, int order, int classzone_idx)
-{
-       unsigned long managed_pages = 0;
-       unsigned long balanced_pages = 0;
-       int i;
-
-       /* Check the watermark levels */
-       for (i = 0; i <= classzone_idx; i++) {
-               struct zone *zone = pgdat->node_zones + i;
-
-               if (!populated_zone(zone))
-                       continue;
-
-               managed_pages += zone->managed_pages;
-
-               /*
-                * A special case here:
-                *
-                * balance_pgdat() skips over all_unreclaimable after
-                * DEF_PRIORITY. Effectively, it considers them balanced so
-                * they must be considered balanced here as well!
-                */
-               if (!pgdat_reclaimable(zone->zone_pgdat)) {
-                       balanced_pages += zone->managed_pages;
-                       continue;
-               }
+       clear_bit(PGDAT_CONGESTED, &zone->zone_pgdat->flags);
+       clear_bit(PGDAT_DIRTY, &zone->zone_pgdat->flags);
 
-               if (zone_balanced(zone, order, false, 0, i))
-                       balanced_pages += zone->managed_pages;
-               else if (!order)
-                       return false;
-       }
-
-       if (order)
-               return balanced_pages >= (managed_pages >> 2);
-       else
-               return true;
+       return true;
 }
 
 /*
@@ -3083,12 +3118,9 @@ static bool pgdat_balanced(pg_data_t *pgdat, int order, int classzone_idx)
  *
  * Returns true if kswapd is ready to sleep
  */
-static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining,
-                                       int classzone_idx)
+static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, int classzone_idx)
 {
-       /* If a direct reclaimer woke kswapd within HZ/10, it's premature */
-       if (remaining)
-               return false;
+       int i;
 
        /*
         * The throttled processes are normally woken up in balance_pgdat() as
@@ -3106,96 +3138,83 @@ static bool prepare_kswapd_sleep(pg_data_t *pgdat, int order, long remaining,
        if (waitqueue_active(&pgdat->pfmemalloc_wait))
                wake_up_all(&pgdat->pfmemalloc_wait);
 
-       return pgdat_balanced(pgdat, order, classzone_idx);
+       for (i = 0; i <= classzone_idx; i++) {
+               struct zone *zone = pgdat->node_zones + i;
+
+               if (!populated_zone(zone))
+                       continue;
+
+               if (!zone_balanced(zone, order, classzone_idx))
+                       return false;
+       }
+
+       return true;
 }
 
 /*
- * kswapd shrinks the zone by the number of pages required to reach
- * the high watermark.
+ * kswapd shrinks a node of pages that are at or below the highest usable
+ * zone that is currently unbalanced.
  *
  * Returns true if kswapd scanned at least the requested number of pages to
  * reclaim or if the lack of progress was due to pages under writeback.
  * This is used to determine if the scanning priority needs to be raised.
  */
-static bool kswapd_shrink_zone(struct zone *zone,
-                              int classzone_idx,
+static bool kswapd_shrink_node(pg_data_t *pgdat,
                               struct scan_control *sc)
 {
-       unsigned long balance_gap;
-       bool lowmem_pressure;
-       struct pglist_data *pgdat = zone->zone_pgdat;
+       struct zone *zone;
+       int z;
 
-       /* Reclaim above the high watermark. */
-       sc->nr_to_reclaim = max(SWAP_CLUSTER_MAX, high_wmark_pages(zone));
+       /* Reclaim a number of pages proportional to the number of zones */
+       sc->nr_to_reclaim = 0;
+       for (z = 0; z <= sc->reclaim_idx; z++) {
+               zone = pgdat->node_zones + z;
+               if (!populated_zone(zone))
+                       continue;
 
-       /*
-        * We put equal pressure on every zone, unless one zone has way too
-        * many pages free already. The "too many pages" is defined as the
-        * high wmark plus a "gap" where the gap is either the low
-        * watermark or 1% of the zone, whichever is smaller.
-        */
-       balance_gap = min(low_wmark_pages(zone), DIV_ROUND_UP(
-                       zone->managed_pages, KSWAPD_ZONE_BALANCE_GAP_RATIO));
+               sc->nr_to_reclaim += max(high_wmark_pages(zone), SWAP_CLUSTER_MAX);
+       }
 
        /*
-        * If there is no low memory pressure or the zone is balanced then no
-        * reclaim is necessary
+        * Historically care was taken to put equal pressure on all zones but
+        * now pressure is applied based on node LRU order.
         */
-       lowmem_pressure = (buffer_heads_over_limit && is_highmem(zone));
-       if (!lowmem_pressure && zone_balanced(zone, sc->order, false,
-                                               balance_gap, classzone_idx))
-               return true;
-
-       shrink_node(zone->zone_pgdat, sc, classzone_idx);
-
-       /* TODO: ANOMALY */
-       clear_bit(PGDAT_WRITEBACK, &pgdat->flags);
+       shrink_node(pgdat, sc);
 
        /*
-        * If a zone reaches its high watermark, consider it to be no longer
-        * congested. It's possible there are dirty pages backed by congested
-        * BDIs but as pressure is relieved, speculatively avoid congestion
-        * waits.
+        * Fragmentation may mean that the system cannot be rebalanced for
+        * high-order allocations. If twice the allocation size has been
+        * reclaimed then recheck watermarks only at order-0 to prevent
+        * excessive reclaim. Assume that a process requested a high-order
+        * can direct reclaim/compact.
         */
-       if (pgdat_reclaimable(zone->zone_pgdat) &&
-           zone_balanced(zone, sc->order, false, 0, classzone_idx)) {
-               clear_bit(PGDAT_CONGESTED, &pgdat->flags);
-               clear_bit(PGDAT_DIRTY, &pgdat->flags);
-       }
+       if (sc->order && sc->nr_reclaimed >= 2UL << sc->order)
+               sc->order = 0;
 
        return sc->nr_scanned >= sc->nr_to_reclaim;
 }
 
 /*
- * For kswapd, balance_pgdat() will work across all this node's zones until
- * they are all at high_wmark_pages(zone).
+ * For kswapd, balance_pgdat() will reclaim pages across a node from zones
+ * that are eligible for use by the caller until at least one zone is
+ * balanced.
  *
- * Returns the highest zone idx kswapd was reclaiming at
- *
- * There is special handling here for zones which are full of pinned pages.
- * This can happen if the pages are all mlocked, or if they are all used by
- * device drivers (say, ZONE_DMA).  Or if they are all in use by hugetlb.
- * What we do is to detect the case where all pages in the zone have been
- * scanned twice and there has been zero successful reclaim.  Mark the zone as
- * dead and from now on, only perform a short scan.  Basically we're polling
- * the zone for when the problem goes away.
+ * Returns the order kswapd finished reclaiming at.
  *
  * kswapd scans the zones in the highmem->normal->dma direction.  It skips
  * zones which have free_pages > high_wmark_pages(zone), but once a zone is
- * found to have free_pages <= high_wmark_pages(zone), we scan that zone and the
- * lower zones regardless of the number of free pages in the lower zones. This
- * interoperates with the page allocator fallback scheme to ensure that aging
- * of pages is balanced across the zones.
+ * found to have free_pages <= high_wmark_pages(zone), any page is that zone
+ * or lower is eligible for reclaim until at least one usable zone is
+ * balanced.
  */
 static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
 {
        int i;
-       int end_zone = 0;       /* Inclusive.  0 = ZONE_DMA */
        unsigned long nr_soft_reclaimed;
        unsigned long nr_soft_scanned;
+       struct zone *zone;
        struct scan_control sc = {
                .gfp_mask = GFP_KERNEL,
-               .reclaim_idx = MAX_NR_ZONES - 1,
                .order = order,
                .priority = DEF_PRIORITY,
                .may_writepage = !laptop_mode,
@@ -3208,102 +3227,77 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
                bool raise_priority = true;
 
                sc.nr_reclaimed = 0;
+               sc.reclaim_idx = classzone_idx;
 
                /*
-                * Scan in the highmem->dma direction for the highest
-                * zone which needs scanning
+                * If the number of buffer_heads exceeds the maximum allowed
+                * then consider reclaiming from all zones. This has a dual
+                * purpose -- on 64-bit systems it is expected that
+                * buffer_heads are stripped during active rotation. On 32-bit
+                * systems, highmem pages can pin lowmem memory and shrinking
+                * buffers can relieve lowmem pressure. Reclaim may still not
+                * go ahead if all eligible zones for the original allocation
+                * request are balanced to avoid excessive reclaim from kswapd.
                 */
-               for (i = pgdat->nr_zones - 1; i >= 0; i--) {
-                       struct zone *zone = pgdat->node_zones + i;
-
-                       if (!populated_zone(zone))
-                               continue;
-
-                       if (sc.priority != DEF_PRIORITY &&
-                           !pgdat_reclaimable(zone->zone_pgdat))
-                               continue;
-
-                       /*
-                        * Do some background aging of the anon list, to give
-                        * pages a chance to be referenced before reclaiming.
-                        */
-                       age_active_anon(zone, &sc);
+               if (buffer_heads_over_limit) {
+                       for (i = MAX_NR_ZONES - 1; i >= 0; i--) {
+                               zone = pgdat->node_zones + i;
+                               if (!populated_zone(zone))
+                                       continue;
 
-                       /*
-                        * If the number of buffer_heads in the machine
-                        * exceeds the maximum allowed level and this node
-                        * has a highmem zone, force kswapd to reclaim from
-                        * it to relieve lowmem pressure.
-                        */
-                       if (buffer_heads_over_limit && is_highmem_idx(i)) {
-                               end_zone = i;
+                               sc.reclaim_idx = i;
                                break;
                        }
+               }
 
-                       if (!zone_balanced(zone, order, false, 0, 0)) {
-                               end_zone = i;
-                               break;
-                       } else {
-                               /*
-                                * If balanced, clear the dirty and congested
-                                * flags
-                                *
-                                * TODO: ANOMALY
-                                */
-                               clear_bit(PGDAT_CONGESTED, &zone->zone_pgdat->flags);
-                               clear_bit(PGDAT_DIRTY, &zone->zone_pgdat->flags);
-                       }
+               /*
+                * Only reclaim if there are no eligible zones. Check from
+                * high to low zone as allocations prefer higher zones.
+                * Scanning from low to high zone would allow congestion to be
+                * cleared during a very small window when a small low
+                * zone was balanced even under extreme pressure when the
+                * overall node may be congested. Note that sc.reclaim_idx
+                * is not used as buffer_heads_over_limit may have adjusted
+                * it.
+                */
+               for (i = classzone_idx; i >= 0; i--) {
+                       zone = pgdat->node_zones + i;
+                       if (!populated_zone(zone))
+                               continue;
+
+                       if (zone_balanced(zone, sc.order, classzone_idx))
+                               goto out;
                }
 
-               if (i < 0)
-                       goto out;
+               /*
+                * Do some background aging of the anon list, to give
+                * pages a chance to be referenced before reclaiming. All
+                * pages are rotated regardless of classzone as this is
+                * about consistent aging.
+                */
+               age_active_anon(pgdat, &sc);
 
                /*
                 * If we're getting trouble reclaiming, start doing writepage
                 * even in laptop mode.
                 */
-               if (sc.priority < DEF_PRIORITY - 2)
+               if (sc.priority < DEF_PRIORITY - 2 || !pgdat_reclaimable(pgdat))
                        sc.may_writepage = 1;
 
+               /* Call soft limit reclaim before calling shrink_node. */
+               sc.nr_scanned = 0;
+               nr_soft_scanned = 0;
+               nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(pgdat, sc.order,
+                                               sc.gfp_mask, &nr_soft_scanned);
+               sc.nr_reclaimed += nr_soft_reclaimed;
+
                /*
-                * Continue scanning in the highmem->dma direction stopping at
-                * the last zone which needs scanning. This may reclaim lowmem
-                * pages that are not necessary for zone balancing but it
-                * preserves LRU ordering. It is assumed that the bulk of
-                * allocation requests can use arbitrary zones with the
-                * possible exception of big highmem:lowmem configurations.
+                * There should be no need to raise the scanning priority if
+                * enough pages are already being scanned that that high
+                * watermark would be met at 100% efficiency.
                 */
-               for (i = end_zone; i >= 0; i--) {
-                       struct zone *zone = pgdat->node_zones + i;
-
-                       if (!populated_zone(zone))
-                               continue;
-
-                       if (sc.priority != DEF_PRIORITY &&
-                           !pgdat_reclaimable(zone->zone_pgdat))
-                               continue;
-
-                       sc.nr_scanned = 0;
-                       sc.reclaim_idx = i;
-
-                       nr_soft_scanned = 0;
-                       /*
-                        * Call soft limit reclaim before calling shrink_zone.
-                        */
-                       nr_soft_reclaimed = mem_cgroup_soft_limit_reclaim(zone,
-                                                       order, sc.gfp_mask,
-                                                       &nr_soft_scanned);
-                       sc.nr_reclaimed += nr_soft_reclaimed;
-
-                       /*
-                        * There should be no need to raise the scanning
-                        * priority if enough pages are already being scanned
-                        * that that high watermark would be met at 100%
-                        * efficiency.
-                        */
-                       if (kswapd_shrink_zone(zone, end_zone, &sc))
-                               raise_priority = false;
-               }
+               if (kswapd_shrink_node(pgdat, &sc))
+                       raise_priority = false;
 
                /*
                 * If the low watermark is met there is no need for processes
@@ -3324,19 +3318,20 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int classzone_idx)
                 */
                if (raise_priority || !sc.nr_reclaimed)
                        sc.priority--;
-       } while (sc.priority >= 1 &&
-                       !pgdat_balanced(pgdat, order, classzone_idx));
+       } while (sc.priority >= 1);
 
 out:
        /*
-        * Return the highest zone idx we were reclaiming at so
-        * prepare_kswapd_sleep() makes the same decisions as here.
+        * Return the order kswapd stopped reclaiming at as
+        * prepare_kswapd_sleep() takes it into account. If another caller
+        * entered the allocator slow path while kswapd was awake, order will
+        * remain at the higher level.
         */
-       return end_zone;
+       return sc.order;
 }
 
-static void kswapd_try_to_sleep(pg_data_t *pgdat, int order,
-                               int classzone_idx, int balanced_classzone_idx)
+static void kswapd_try_to_sleep(pg_data_t *pgdat, int alloc_order, int reclaim_order,
+                               unsigned int classzone_idx)
 {
        long remaining = 0;
        DEFINE_WAIT(wait);
@@ -3347,8 +3342,7 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int order,
        prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
 
        /* Try to sleep for a short interval */
-       if (prepare_kswapd_sleep(pgdat, order, remaining,
-                                               balanced_classzone_idx)) {
+       if (prepare_kswapd_sleep(pgdat, reclaim_order, classzone_idx)) {
                /*
                 * Compaction records what page blocks it recently failed to
                 * isolate pages from and skips them in the future scanning.
@@ -3361,9 +3355,20 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int order,
                 * We have freed the memory, now we should compact it to make
                 * allocation of the requested order possible.
                 */
-               wakeup_kcompactd(pgdat, order, classzone_idx);
+               wakeup_kcompactd(pgdat, alloc_order, classzone_idx);
 
                remaining = schedule_timeout(HZ/10);
+
+               /*
+                * If woken prematurely then reset kswapd_classzone_idx and
+                * order. The values will either be from a wakeup request or
+                * the previous request that slept prematurely.
+                */
+               if (remaining) {
+                       pgdat->kswapd_classzone_idx = max(pgdat->kswapd_classzone_idx, classzone_idx);
+                       pgdat->kswapd_order = max(pgdat->kswapd_order, reclaim_order);
+               }
+
                finish_wait(&pgdat->kswapd_wait, &wait);
                prepare_to_wait(&pgdat->kswapd_wait, &wait, TASK_INTERRUPTIBLE);
        }
@@ -3372,8 +3377,8 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int order,
         * After a short sleep, check if it was a premature sleep. If not, then
         * go fully to sleep until explicitly woken up.
         */
-       if (prepare_kswapd_sleep(pgdat, order, remaining,
-                                               balanced_classzone_idx)) {
+       if (!remaining &&
+           prepare_kswapd_sleep(pgdat, reclaim_order, classzone_idx)) {
                trace_mm_vmscan_kswapd_sleep(pgdat->node_id);
 
                /*
@@ -3414,9 +3419,7 @@ static void kswapd_try_to_sleep(pg_data_t *pgdat, int order,
  */
 static int kswapd(void *p)
 {
-       unsigned long order, new_order;
-       int classzone_idx, new_classzone_idx;
-       int balanced_classzone_idx;
+       unsigned int alloc_order, reclaim_order, classzone_idx;
        pg_data_t *pgdat = (pg_data_t*)p;
        struct task_struct *tsk = current;
 
@@ -3446,38 +3449,20 @@ static int kswapd(void *p)
        tsk->flags |= PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD;
        set_freezable();
 
-       order = new_order = 0;
-       classzone_idx = new_classzone_idx = pgdat->nr_zones - 1;
-       balanced_classzone_idx = classzone_idx;
+       pgdat->kswapd_order = alloc_order = reclaim_order = 0;
+       pgdat->kswapd_classzone_idx = classzone_idx = 0;
        for ( ; ; ) {
                bool ret;
 
-               /*
-                * While we were reclaiming, there might have been another
-                * wakeup, so check the values.
-                */
-               new_order = pgdat->kswapd_max_order;
-               new_classzone_idx = pgdat->classzone_idx;
-               pgdat->kswapd_max_order =  0;
-               pgdat->classzone_idx = pgdat->nr_zones - 1;
+kswapd_try_sleep:
+               kswapd_try_to_sleep(pgdat, alloc_order, reclaim_order,
+                                       classzone_idx);
 
-               if (order < new_order || classzone_idx > new_classzone_idx) {
-                       /*
-                        * Don't sleep if someone wants a larger 'order'
-                        * allocation or has tigher zone constraints
-                        */
-                       order = new_order;
-                       classzone_idx = new_classzone_idx;
-               } else {
-                       kswapd_try_to_sleep(pgdat, order, classzone_idx,
-                                               balanced_classzone_idx);
-                       order = pgdat->kswapd_max_order;
-                       classzone_idx = pgdat->classzone_idx;
-                       new_order = order;
-                       new_classzone_idx = classzone_idx;
-                       pgdat->kswapd_max_order = 0;
-                       pgdat->classzone_idx = pgdat->nr_zones - 1;
-               }
+               /* Read the new order and classzone_idx */
+               alloc_order = reclaim_order = pgdat->kswapd_order;
+               classzone_idx = pgdat->kswapd_classzone_idx;
+               pgdat->kswapd_order = 0;
+               pgdat->kswapd_classzone_idx = 0;
 
                ret = try_to_freeze();
                if (kthread_should_stop())
@@ -3487,11 +3472,25 @@ static int kswapd(void *p)
                 * We can speed up thawing tasks if we don't call balance_pgdat
                 * after returning from the refrigerator
                 */
-               if (!ret) {
-                       trace_mm_vmscan_kswapd_wake(pgdat->node_id, order);
-                       balanced_classzone_idx = balance_pgdat(pgdat, order,
-                                                               classzone_idx);
-               }
+               if (ret)
+                       continue;
+
+               /*
+                * Reclaim begins at the requested order but if a high-order
+                * reclaim fails then kswapd falls back to reclaiming for
+                * order-0. If that happens, kswapd will consider sleeping
+                * for the order it finished reclaiming at (reclaim_order)
+                * but kcompactd is woken to compact for the original
+                * request (alloc_order).
+                */
+               trace_mm_vmscan_kswapd_wake(pgdat->node_id, classzone_idx,
+                                               alloc_order);
+               reclaim_order = balance_pgdat(pgdat, alloc_order, classzone_idx);
+               if (reclaim_order < alloc_order)
+                       goto kswapd_try_sleep;
+
+               alloc_order = reclaim_order = pgdat->kswapd_order;
+               classzone_idx = pgdat->kswapd_classzone_idx;
        }
 
        tsk->flags &= ~(PF_MEMALLOC | PF_SWAPWRITE | PF_KSWAPD);
@@ -3507,6 +3506,7 @@ static int kswapd(void *p)
 void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
 {
        pg_data_t *pgdat;
+       int z;
 
        if (!populated_zone(zone))
                return;
@@ -3514,14 +3514,20 @@ void wakeup_kswapd(struct zone *zone, int order, enum zone_type classzone_idx)
        if (!cpuset_zone_allowed(zone, GFP_KERNEL | __GFP_HARDWALL))
                return;
        pgdat = zone->zone_pgdat;
-       if (pgdat->kswapd_max_order < order) {
-               pgdat->kswapd_max_order = order;
-               pgdat->classzone_idx = min(pgdat->classzone_idx, classzone_idx);
-       }
+       pgdat->kswapd_classzone_idx = max(pgdat->kswapd_classzone_idx, classzone_idx);
+       pgdat->kswapd_order = max(pgdat->kswapd_order, order);
        if (!waitqueue_active(&pgdat->kswapd_wait))
                return;
-       if (zone_balanced(zone, order, true, 0, 0))
-               return;
+
+       /* Only wake kswapd if all zones are unbalanced */
+       for (z = 0; z <= classzone_idx; z++) {
+               zone = pgdat->node_zones + z;
+               if (!populated_zone(zone))
+                       continue;
+
+               if (zone_balanced(zone, order, classzone_idx))
+                       return;
+       }
 
        trace_mm_vmscan_wakeup_kswapd(pgdat->node_id, zone_idx(zone), order);
        wake_up_interruptible(&pgdat->kswapd_wait);
@@ -3644,12 +3650,12 @@ module_init(kswapd_init)
 
 #ifdef CONFIG_NUMA
 /*
- * Zone reclaim mode
+ * Node reclaim mode
  *
- * If non-zero call zone_reclaim when the number of free pages falls below
+ * If non-zero call node_reclaim when the number of free pages falls below
  * the watermarks.
  */
-int zone_reclaim_mode __read_mostly;
+int node_reclaim_mode __read_mostly;
 
 #define RECLAIM_OFF 0
 #define RECLAIM_ZONE (1<<0)    /* Run shrink_inactive_list on the zone */
@@ -3657,14 +3663,14 @@ int zone_reclaim_mode __read_mostly;
 #define RECLAIM_UNMAP (1<<2)   /* Unmap pages during reclaim */
 
 /*
- * Priority for ZONE_RECLAIM. This determines the fraction of pages
+ * Priority for NODE_RECLAIM. This determines the fraction of pages
  * of a node considered for each zone_reclaim. 4 scans 1/16th of
  * a zone.
  */
-#define ZONE_RECLAIM_PRIORITY 4
+#define NODE_RECLAIM_PRIORITY 4
 
 /*
- * Percentage of pages in a zone that must be unmapped for zone_reclaim to
+ * Percentage of pages in a zone that must be unmapped for node_reclaim to
  * occur.
  */
 int sysctl_min_unmapped_ratio = 1;
@@ -3675,11 +3681,11 @@ int sysctl_min_unmapped_ratio = 1;
  */
 int sysctl_min_slab_ratio = 5;
 
-static inline unsigned long zone_unmapped_file_pages(struct zone *zone)
+static inline unsigned long node_unmapped_file_pages(struct pglist_data *pgdat)
 {
-       unsigned long file_mapped = zone_page_state(zone, NR_FILE_MAPPED);
-       unsigned long file_lru = node_page_state(zone->zone_pgdat, NR_INACTIVE_FILE) +
-               node_page_state(zone->zone_pgdat, NR_ACTIVE_FILE);
+       unsigned long file_mapped = node_page_state(pgdat, NR_FILE_MAPPED);
+       unsigned long file_lru = node_page_state(pgdat, NR_INACTIVE_FILE) +
+               node_page_state(pgdat, NR_ACTIVE_FILE);
 
        /*
         * It's possible for there to be more file mapped pages than
@@ -3690,7 +3696,7 @@ static inline unsigned long zone_unmapped_file_pages(struct zone *zone)
 }
 
 /* Work out how many page cache pages we can reclaim in this reclaim_mode */
-static unsigned long zone_pagecache_reclaimable(struct zone *zone)
+static unsigned long node_pagecache_reclaimable(struct pglist_data *pgdat)
 {
        unsigned long nr_pagecache_reclaimable;
        unsigned long delta = 0;
@@ -3698,17 +3704,17 @@ static unsigned long zone_pagecache_reclaimable(struct zone *zone)
        /*
         * If RECLAIM_UNMAP is set, then all file pages are considered
         * potentially reclaimable. Otherwise, we have to worry about
-        * pages like swapcache and zone_unmapped_file_pages() provides
+        * pages like swapcache and node_unmapped_file_pages() provides
         * a better estimate
         */
-       if (zone_reclaim_mode & RECLAIM_UNMAP)
-               nr_pagecache_reclaimable = zone_page_state(zone, NR_FILE_PAGES);
+       if (node_reclaim_mode & RECLAIM_UNMAP)
+               nr_pagecache_reclaimable = node_page_state(pgdat, NR_FILE_PAGES);
        else
-               nr_pagecache_reclaimable = zone_unmapped_file_pages(zone);
+               nr_pagecache_reclaimable = node_unmapped_file_pages(pgdat);
 
        /* If we can't clean pages, remove dirty pages from consideration */
-       if (!(zone_reclaim_mode & RECLAIM_WRITE))
-               delta += zone_page_state(zone, NR_FILE_DIRTY);
+       if (!(node_reclaim_mode & RECLAIM_WRITE))
+               delta += node_page_state(pgdat, NR_FILE_DIRTY);
 
        /* Watch for any possible underflows due to delta */
        if (unlikely(delta > nr_pagecache_reclaimable))
@@ -3718,23 +3724,24 @@ static unsigned long zone_pagecache_reclaimable(struct zone *zone)
 }
 
 /*
- * Try to free up some pages from this zone through reclaim.
+ * Try to free up some pages from this node through reclaim.
  */
-static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
+static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order)
 {
        /* Minimum pages needed in order to stay on node */
        const unsigned long nr_pages = 1 << order;
        struct task_struct *p = current;
        struct reclaim_state reclaim_state;
+       int classzone_idx = gfp_zone(gfp_mask);
        struct scan_control sc = {
                .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
                .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)),
                .order = order,
-               .priority = ZONE_RECLAIM_PRIORITY,
-               .may_writepage = !!(zone_reclaim_mode & RECLAIM_WRITE),
-               .may_unmap = !!(zone_reclaim_mode & RECLAIM_UNMAP),
+               .priority = NODE_RECLAIM_PRIORITY,
+               .may_writepage = !!(node_reclaim_mode & RECLAIM_WRITE),
+               .may_unmap = !!(node_reclaim_mode & RECLAIM_UNMAP),
                .may_swap = 1,
-               .reclaim_idx = zone_idx(zone),
+               .reclaim_idx = classzone_idx,
        };
 
        cond_resched();
@@ -3748,13 +3755,13 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
        reclaim_state.reclaimed_slab = 0;
        p->reclaim_state = &reclaim_state;
 
-       if (zone_pagecache_reclaimable(zone) > zone->min_unmapped_pages) {
+       if (node_pagecache_reclaimable(pgdat) > pgdat->min_unmapped_pages) {
                /*
                 * Free memory by calling shrink zone with increasing
                 * priorities until we have enough memory freed.
                 */
                do {
-                       shrink_node(zone->zone_pgdat, &sc, zone_idx(zone));
+                       shrink_node(pgdat, &sc);
                } while (sc.nr_reclaimed < nr_pages && --sc.priority >= 0);
        }
 
@@ -3764,49 +3771,47 @@ static int __zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
        return sc.nr_reclaimed >= nr_pages;
 }
 
-int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
+int node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned int order)
 {
-       int node_id;
        int ret;
 
        /*
-        * Zone reclaim reclaims unmapped file backed pages and
+        * Node reclaim reclaims unmapped file backed pages and
         * slab pages if we are over the defined limits.
         *
         * A small portion of unmapped file backed pages is needed for
         * file I/O otherwise pages read by file I/O will be immediately
-        * thrown out if the zone is overallocated. So we do not reclaim
-        * if less than a specified percentage of the zone is used by
+        * thrown out if the node is overallocated. So we do not reclaim
+        * if less than a specified percentage of the node is used by
         * unmapped file backed pages.
         */
-       if (zone_pagecache_reclaimable(zone) <= zone->min_unmapped_pages &&
-           zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages)
-               return ZONE_RECLAIM_FULL;
+       if (node_pagecache_reclaimable(pgdat) <= pgdat->min_unmapped_pages &&
+           sum_zone_node_page_state(pgdat->node_id, NR_SLAB_RECLAIMABLE) <= pgdat->min_slab_pages)
+               return NODE_RECLAIM_FULL;
 
-       if (!pgdat_reclaimable(zone->zone_pgdat))
-               return ZONE_RECLAIM_FULL;
+       if (!pgdat_reclaimable(pgdat))
+               return NODE_RECLAIM_FULL;
 
        /*
         * Do not scan if the allocation should not be delayed.
         */
        if (!gfpflags_allow_blocking(gfp_mask) || (current->flags & PF_MEMALLOC))
-               return ZONE_RECLAIM_NOSCAN;
+               return NODE_RECLAIM_NOSCAN;
 
        /*
-        * Only run zone reclaim on the local zone or on zones that do not
+        * Only run node reclaim on the local node or on nodes that do not
         * have associated processors. This will favor the local processor
         * over remote processors and spread off node memory allocations
         * as wide as possible.
         */
-       node_id = zone_to_nid(zone);
-       if (node_state(node_id, N_CPU) && node_id != numa_node_id())
-               return ZONE_RECLAIM_NOSCAN;
+       if (node_state(pgdat->node_id, N_CPU) && pgdat->node_id != numa_node_id())
+               return NODE_RECLAIM_NOSCAN;
 
-       if (test_and_set_bit(ZONE_RECLAIM_LOCKED, &zone->flags))
-               return ZONE_RECLAIM_NOSCAN;
+       if (test_and_set_bit(PGDAT_RECLAIM_LOCKED, &pgdat->flags))
+               return NODE_RECLAIM_NOSCAN;
 
-       ret = __zone_reclaim(zone, gfp_mask, order);
-       clear_bit(ZONE_RECLAIM_LOCKED, &zone->flags);
+       ret = __node_reclaim(pgdat, gfp_mask, order);
+       clear_bit(PGDAT_RECLAIM_LOCKED, &pgdat->flags);
 
        if (!ret)
                count_vm_event(PGSCAN_ZONE_RECLAIM_FAILED);
@@ -3845,24 +3850,23 @@ int page_evictable(struct page *page)
 void check_move_unevictable_pages(struct page **pages, int nr_pages)
 {
        struct lruvec *lruvec;
-       struct zone *zone = NULL;
+       struct pglist_data *pgdat = NULL;
        int pgscanned = 0;
        int pgrescued = 0;
        int i;
 
        for (i = 0; i < nr_pages; i++) {
                struct page *page = pages[i];
-               struct zone *pagezone;
+               struct pglist_data *pagepgdat = page_pgdat(page);
 
                pgscanned++;
-               pagezone = page_zone(page);
-               if (pagezone != zone) {
-                       if (zone)
-                               spin_unlock_irq(zone_lru_lock(zone));
-                       zone = pagezone;
-                       spin_lock_irq(zone_lru_lock(zone));
+               if (pagepgdat != pgdat) {
+                       if (pgdat)
+                               spin_unlock_irq(&pgdat->lru_lock);
+                       pgdat = pagepgdat;
+                       spin_lock_irq(&pgdat->lru_lock);
                }
-               lruvec = mem_cgroup_page_lruvec(page, zone->zone_pgdat);
+               lruvec = mem_cgroup_page_lruvec(page, pgdat);
 
                if (!PageLRU(page) || !PageUnevictable(page))
                        continue;
@@ -3878,10 +3882,10 @@ void check_move_unevictable_pages(struct page **pages, int nr_pages)
                }
        }
 
-       if (zone) {
+       if (pgdat) {
                __count_vm_events(UNEVICTABLE_PGRESCUED, pgrescued);
                __count_vm_events(UNEVICTABLE_PGSCANNED, pgscanned);
-               spin_unlock_irq(zone_lru_lock(zone));
+               spin_unlock_irq(&pgdat->lru_lock);
        }
 }
 #endif /* CONFIG_SHMEM */