diff options
Diffstat (limited to 'mm/zswap.c')
| -rw-r--r-- | mm/zswap.c | 40 |
1 files changed, 33 insertions, 7 deletions
diff --git a/mm/zswap.c b/mm/zswap.c index bd97f9824d8a..71b75ff1f3fb 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -1287,10 +1287,10 @@ static struct shrinker *zswap_alloc_shrinker(void) static int shrink_memcg(struct mem_cgroup *memcg) { - int nid, shrunk = 0; + int nid, shrunk = 0, scanned = 0; if (!mem_cgroup_zswap_writeback_enabled(memcg)) - return -EINVAL; + return -ENOENT; /* * Skip zombies because their LRUs are reparented and we would be @@ -1304,21 +1304,34 @@ static int shrink_memcg(struct mem_cgroup *memcg) shrunk += list_lru_walk_one(&zswap_list_lru, nid, memcg, &shrink_memcg_cb, NULL, &nr_to_walk); + scanned += 1 - nr_to_walk; } + + if (!scanned) + return -ENOENT; + return shrunk ? 0 : -EAGAIN; } static void shrink_worker(struct work_struct *w) { struct mem_cgroup *memcg; - int ret, failures = 0; + int ret, failures = 0, attempts = 0; unsigned long thr; /* Reclaim down to the accept threshold */ thr = zswap_accept_thr_pages(); /* - * Global reclaim will select cgroup in a round-robin fashion. + * Global reclaim will select cgroup in a round-robin fashion from all + * online memcgs, but memcgs that have no pages in zswap and + * writeback-disabled memcgs (memory.zswap.writeback=0) are not + * candidates for shrinking. + * + * Shrinking will be aborted if we encounter the following + * MAX_RECLAIM_RETRIES times: + * - No writeback-candidate memcgs found in a memcg tree walk. + * - Shrinking a writeback-candidate memcg failed. * * We save iteration cursor memcg into zswap_next_shrink, * which can be modified by the offline memcg cleaner @@ -1354,9 +1367,14 @@ static void shrink_worker(struct work_struct *w) spin_unlock(&zswap_shrink_lock); if (!memcg) { - if (++failures == MAX_RECLAIM_RETRIES) + /* + * Continue shrinking without incrementing failures if + * we found candidate memcgs in the last tree walk. + */ + if (!attempts && ++failures == MAX_RECLAIM_RETRIES) break; + attempts = 0; goto resched; } @@ -1364,8 +1382,16 @@ static void shrink_worker(struct work_struct *w) /* drop the extra reference */ mem_cgroup_put(memcg); - if (ret == -EINVAL) - break; + /* + * There are no writeback-candidate pages in the memcg. + * This is not an issue as long as we can find another memcg + * with pages in zswap. Skip this without incrementing attempts + * and failures. + */ + if (ret == -ENOENT) + continue; + ++attempts; + if (ret && ++failures == MAX_RECLAIM_RETRIES) break; resched: |