1 files changed, 13 insertions, 14 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 44df66a98f2a..a6c5d0b28321 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -88,9 +88,6 @@ struct scan_control {
         /* Can pages be swapped as part of reclaim? */
         unsigned int may_swap:1;
 
-        /* e.g. boosted watermark reclaim leaves slabs alone */
-        unsigned int may_shrinkslab:1;
-
         /*
          * Cgroups are not reclaimed below their configured memory.low,
          * unless we threaten to OOM. If any cgroups are skipped due to
@@ -699,7 +696,14 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
         unsigned long ret, freed = 0;
         struct shrinker *shrinker;
 
-        if (!mem_cgroup_is_root(memcg))
+        /*
+         * The root memcg might be allocated even though memcg is disabled
+         * via "cgroup_disable=memory" boot parameter.  This could make
+         * mem_cgroup_is_root() return false, then just run memcg slab
+         * shrink, but skip global shrink.  This may result in premature
+         * oom.
+         */
+        if (!mem_cgroup_disabled() && !mem_cgroup_is_root(memcg))
                 return shrink_slab_memcg(gfp_mask, nid, memcg, priority);
 
         if (!down_read_trylock(&shrinker_rwsem))
@@ -2707,10 +2711,8 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
                         shrink_node_memcg(pgdat, memcg, sc, &lru_pages);
                         node_lru_pages += lru_pages;
 
-                        if (sc->may_shrinkslab) {
-                                shrink_slab(sc->gfp_mask, pgdat->node_id,
-                                    memcg, sc->priority);
-                        }
+                        shrink_slab(sc->gfp_mask, pgdat->node_id, memcg,
+                                        sc->priority);
 
                         /* Record the group's reclaim efficiency */
                         vmpressure(sc->gfp_mask, memcg, false,
@@ -3187,7 +3189,6 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
                 .may_writepage = !laptop_mode,
                 .may_unmap = 1,
                 .may_swap = 1,
-                .may_shrinkslab = 1,
         };
 
         /*
@@ -3219,6 +3220,7 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
 
 #ifdef CONFIG_MEMCG
 
+/* Only used by soft limit reclaim. Do not reuse for anything else. */
 unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
                                                 gfp_t gfp_mask, bool noswap,
                                                 pg_data_t *pgdat,
@@ -3231,11 +3233,11 @@ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
                 .may_unmap = 1,
                 .reclaim_idx = MAX_NR_ZONES - 1,
                 .may_swap = !noswap,
-                .may_shrinkslab = 1,
         };
         unsigned long lru_pages;
 
-        set_task_reclaim_state(current, &sc.reclaim_state);
+        WARN_ON_ONCE(!current->reclaim_state);
+
         sc.gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
                         (GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK);
 
@@ -3253,7 +3255,6 @@ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
 
         trace_mm_vmscan_memcg_softlimit_reclaim_end(sc.nr_reclaimed);
 
-        set_task_reclaim_state(current, NULL);
         *nr_scanned = sc.nr_scanned;
 
         return sc.nr_reclaimed;
@@ -3279,7 +3280,6 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
                 .may_writepage = !laptop_mode,
                 .may_unmap = 1,
                 .may_swap = may_swap,
-                .may_shrinkslab = 1,
         };
 
         set_task_reclaim_state(current, &sc.reclaim_state);
@@ -3591,7 +3591,6 @@ restart:
                  */
                 sc.may_writepage = !laptop_mode && !nr_boost_reclaim;
                 sc.may_swap = !nr_boost_reclaim;
-                sc.may_shrinkslab = !nr_boost_reclaim;
 
                 /*
                  * Do some background aging of the anon list, to give