mm: vmscan: move swappiness out of scan_control

Swappiness is determined for each scanned memcg individually in
shrink_zone() and is not a parameter that applies throughout the reclaim
scan.  Move it out of struct scan_control to prevent accidental use of a
stale value.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 13 insertions, 14 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 74a9e0ae09b0..c28b8981e56a 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -89,9 +89,6 @@ struct scan_control {
         /* Scan (total_size >> priority) pages at once */
         int priority;
 
-        /* anon vs. file LRUs scanning "ratio" */
-        int swappiness;
-
         /*
          * The memory cgroup that hit its limit and as a result is the
          * primary target of this reclaim invocation.
@@ -1868,8 +1865,8 @@ enum scan_balance {
  * nr[0] = anon inactive pages to scan; nr[1] = anon active pages to scan
  * nr[2] = file inactive pages to scan; nr[3] = file active pages to scan
  */
-static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
-                           unsigned long *nr)
+static void get_scan_count(struct lruvec *lruvec, int swappiness,
+                           struct scan_control *sc, unsigned long *nr)
 {
         struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
         u64 fraction[2];
@@ -1912,7 +1909,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
          * using the memory controller's swap limit feature would be
          * too expensive.
          */
-        if (!global_reclaim(sc) && !sc->swappiness) {
+        if (!global_reclaim(sc) && !swappiness) {
                 scan_balance = SCAN_FILE;
                 goto out;
         }
@@ -1922,7 +1919,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
          * system is close to OOM, scan both anon and file equally
          * (unless the swappiness setting disagrees with swapping).
          */
-        if (!sc->priority && sc->swappiness) {
+        if (!sc->priority && swappiness) {
                 scan_balance = SCAN_EQUAL;
                 goto out;
         }
@@ -1965,7 +1962,7 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc,
          * With swappiness at 100, anonymous and file have the same priority.
          * This scanning priority is essentially the inverse of IO cost.
          */
-        anon_prio = sc->swappiness;
+        anon_prio = swappiness;
         file_prio = 200 - anon_prio;
 
         /*
@@ -2055,7 +2052,8 @@ out:
 /*
  * This is a basic per-zone page freer.  Used by both kswapd and direct reclaim.
  */
-static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
+static void shrink_lruvec(struct lruvec *lruvec, int swappiness,
+                          struct scan_control *sc)
 {
         unsigned long nr[NR_LRU_LISTS];
         unsigned long targets[NR_LRU_LISTS];
@@ -2066,7 +2064,7 @@ static void shrink_lruvec(struct lruvec *lruvec, struct scan_control *sc)
         struct blk_plug plug;
         bool scan_adjusted;
 
-        get_scan_count(lruvec, sc, nr);
+        get_scan_count(lruvec, swappiness, sc, nr);
 
         /* Record the original scan target for proportional adjustments later */
         memcpy(targets, nr, sizeof(nr));
@@ -2263,11 +2261,12 @@ static bool shrink_zone(struct zone *zone, struct scan_control *sc)
                 memcg = mem_cgroup_iter(root, NULL, &reclaim);
                 do {
                         struct lruvec *lruvec;
+                        int swappiness;
 
                         lruvec = mem_cgroup_zone_lruvec(zone, memcg);
+                        swappiness = mem_cgroup_swappiness(memcg);
 
-                        sc->swappiness = mem_cgroup_swappiness(memcg);
-                        shrink_lruvec(lruvec, sc);
+                        shrink_lruvec(lruvec, swappiness, sc);
 
                         /*
                          * Direct reclaim and kswapd have to scan all memory
@@ -2714,10 +2713,10 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg,
                 .may_swap = !noswap,
                 .order = 0,
                 .priority = 0,
-                .swappiness = mem_cgroup_swappiness(memcg),
                 .target_mem_cgroup = memcg,
         };
         struct lruvec *lruvec = mem_cgroup_zone_lruvec(zone, memcg);
+        int swappiness = mem_cgroup_swappiness(memcg);
 
         sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
                         (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
@@ -2733,7 +2732,7 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg,
          * will pick up pages from other mem cgroup's as well. We hack
          * the priority and make it zero.
          */
-        shrink_lruvec(lruvec, &sc);
+        shrink_lruvec(lruvec, swappiness, &sc);
 
         trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);