mm, vmscan: cleanup lru size claculations

lruvec_lru_size returns the full size of the LRU list while we sometimes
need a value reduced only to eligible zones (e.g.  for lowmem requests).
inactive_list_is_low is one such user.  Later patches will add more of
them.  Add a new parameter to lruvec_lru_size and allow it filter out
zones which are not eligible for the given context.

Link: http://lkml.kernel.org/r/20170117103702.28542-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

3 files changed, 46 insertions, 47 deletions

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index f4aac87adcc3..82fc632fd11d 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -779,7 +779,7 @@ static inline struct pglist_data *lruvec_pgdat(struct lruvec *lruvec)
 #endif
 }
 
-extern unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru);
+extern unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx);
 
 #ifdef CONFIG_HAVE_MEMORY_PRESENT
 void memory_present(int nid, unsigned long start, unsigned long end);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 277e105646a5..e7c75a3c6b53 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -234,22 +234,39 @@ bool pgdat_reclaimable(struct pglist_data *pgdat)
                 pgdat_reclaimable_pages(pgdat) * 6;
 }
 
-unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru)
+/**
+ * lruvec_lru_size -  Returns the number of pages on the given LRU list.
+ * @lruvec: lru vector
+ * @lru: lru to use
+ * @zone_idx: zones to consider (use MAX_NR_ZONES for the whole LRU list)
+ */
+unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx)
 {
+        unsigned long lru_size;
+        int zid;
+
         if (!mem_cgroup_disabled())
-                return mem_cgroup_get_lru_size(lruvec, lru);
+                lru_size = mem_cgroup_get_lru_size(lruvec, lru);
+        else
+                lru_size = node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru);
 
-        return node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru);
-}
+        for (zid = zone_idx + 1; zid < MAX_NR_ZONES; zid++) {
+                struct zone *zone = &lruvec_pgdat(lruvec)->node_zones[zid];
+                unsigned long size;
 
-unsigned long lruvec_zone_lru_size(struct lruvec *lruvec, enum lru_list lru,
-                                   int zone_idx)
-{
-        if (!mem_cgroup_disabled())
-                return mem_cgroup_get_zone_lru_size(lruvec, lru, zone_idx);
+                if (!managed_zone(zone))
+                        continue;
+
+                if (!mem_cgroup_disabled())
+                        size = mem_cgroup_get_zone_lru_size(lruvec, lru, zid);
+                else
+                        size = zone_page_state(&lruvec_pgdat(lruvec)->node_zones[zid],
+                                       NR_ZONE_LRU_BASE + lru);
+                lru_size -= min(size, lru_size);
+        }
+
+        return lru_size;
 
-        return zone_page_state(&lruvec_pgdat(lruvec)->node_zones[zone_idx],
-                               NR_ZONE_LRU_BASE + lru);
 }
 
 /*
@@ -2049,11 +2066,10 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
                                                 struct scan_control *sc, bool trace)
 {
         unsigned long inactive_ratio;
-        unsigned long total_inactive, inactive;
-        unsigned long total_active, active;
+        unsigned long inactive, active;
+        enum lru_list inactive_lru = file * LRU_FILE;
+        enum lru_list active_lru = file * LRU_FILE + LRU_ACTIVE;
         unsigned long gb;
-        struct pglist_data *pgdat = lruvec_pgdat(lruvec);
-        int zid;
 
         /*
          * If we don't have swap space, anonymous page deactivation
@@ -2062,27 +2078,8 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
         if (!file && !total_swap_pages)
                 return false;
 
-        total_inactive = inactive = lruvec_lru_size(lruvec, file * LRU_FILE);
-        total_active = 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 (!managed_zone(zone))
-                        continue;
-
-                inactive_zone = lruvec_zone_lru_size(lruvec, file * LRU_FILE, zid);
-                active_zone = lruvec_zone_lru_size(lruvec, (file * LRU_FILE) + LRU_ACTIVE, zid);
-
-                inactive -= min(inactive, inactive_zone);
-                active -= min(active, active_zone);
-        }
+        inactive = lruvec_lru_size(lruvec, inactive_lru, sc->reclaim_idx);
+        active = lruvec_lru_size(lruvec, active_lru, sc->reclaim_idx);
 
         gb = (inactive + active) >> (30 - PAGE_SHIFT);
         if (gb)
@@ -2091,10 +2088,12 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
                 inactive_ratio = 1;
 
         if (trace)
-                trace_mm_vmscan_inactive_list_is_low(pgdat->node_id,
+                trace_mm_vmscan_inactive_list_is_low(lruvec_pgdat(lruvec)->node_id,
                                 sc->reclaim_idx,
-                                total_inactive, inactive,
-                                total_active, active, inactive_ratio, file);
+                                lruvec_lru_size(lruvec, inactive_lru, MAX_NR_ZONES), inactive,
+                                lruvec_lru_size(lruvec, active_lru, MAX_NR_ZONES), active,
+                                inactive_ratio, file);
+
         return inactive * inactive_ratio < active;
 }
 
@@ -2234,7 +2233,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
          * system is under heavy pressure.
          */
         if (!inactive_list_is_low(lruvec, true, sc, false) &&
-            lruvec_lru_size(lruvec, LRU_INACTIVE_FILE) >> sc->priority) {
+            lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES) >> sc->priority) {
                 scan_balance = SCAN_FILE;
                 goto out;
         }
@@ -2260,10 +2259,10 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
          * anon in [0], file in [1]
          */
 
-        anon  = lruvec_lru_size(lruvec, LRU_ACTIVE_ANON) +
-                lruvec_lru_size(lruvec, LRU_INACTIVE_ANON);
-        file  = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE) +
-                lruvec_lru_size(lruvec, LRU_INACTIVE_FILE);
+        anon  = lruvec_lru_size(lruvec, LRU_ACTIVE_ANON, MAX_NR_ZONES) +
+                lruvec_lru_size(lruvec, LRU_INACTIVE_ANON, MAX_NR_ZONES);
+        file  = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE, MAX_NR_ZONES) +
+                lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES);
 
         spin_lock_irq(&pgdat->lru_lock);
         if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
@@ -2301,7 +2300,7 @@ out:
                         unsigned long size;
                         unsigned long scan;
 
-                        size = lruvec_lru_size(lruvec, lru);
+                        size = lruvec_lru_size(lruvec, lru, MAX_NR_ZONES);
                         scan = size >> sc->priority;
 
                         if (!scan && pass && force_scan)
diff --git a/mm/workingset.c b/mm/workingset.c
index abb58ffa3c64..a67f5796b995 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -267,7 +267,7 @@ bool workingset_refault(void *shadow)
         }
         lruvec = mem_cgroup_lruvec(pgdat, memcg);
         refault = atomic_long_read(&lruvec->inactive_age);
-        active_file = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE);
+        active_file = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE, MAX_NR_ZONES);
         rcu_read_unlock();
 
         /*