diff options
| -rw-r--r-- | mm/memcontrol.c | 2 | ||||
| -rw-r--r-- | mm/vmscan.c | 26 |
2 files changed, 26 insertions, 2 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 55c010a58535..6a921890739f 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -430,6 +430,8 @@ void memcg_set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id) rcu_read_lock(); map = rcu_dereference(memcg->nodeinfo[nid]->shrinker_map); + /* Pairs with smp mb in shrink_slab() */ + smp_mb__before_atomic(); set_bit(shrinker_id, map->map); rcu_read_unlock(); } diff --git a/mm/vmscan.c b/mm/vmscan.c index 8199e1b9a204..93fdd0375b64 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -596,8 +596,30 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid, continue; ret = do_shrink_slab(&sc, shrinker, priority); - if (ret == SHRINK_EMPTY) - ret = 0; + if (ret == SHRINK_EMPTY) { + clear_bit(i, map->map); + /* + * After the shrinker reported that it had no objects to + * free, but before we cleared the corresponding bit in + * the memcg shrinker map, a new object might have been + * added. To make sure, we have the bit set in this + * case, we invoke the shrinker one more time and reset + * the bit if it reports that it is not empty anymore. + * The memory barrier here pairs with the barrier in + * memcg_set_shrinker_bit(): + * + * list_lru_add() shrink_slab_memcg() + * list_add_tail() clear_bit() + * <MB> <MB> + * set_bit() do_shrink_slab() + */ + smp_mb__after_atomic(); + ret = do_shrink_slab(&sc, shrinker, priority); + if (ret == SHRINK_EMPTY) + ret = 0; + else + memcg_set_shrinker_bit(memcg, nid, i); + } freed += ret; if (rwsem_is_contended(&shrinker_rwsem)) { |