From e35606e4167dd55d48aa6232c074137577818add Mon Sep 17 00:00:00 2001 From: Chengming Zhou Date: Tue, 5 Mar 2024 07:53:45 +0000 Subject: mm/zswap: global lru and shrinker shared by all zswap_pools fix Commit bf9b7df23cb3 ("mm/zswap: global lru and shrinker shared by all zswap_pools") introduced a new lock to protect zswap_next_shrink, instead of reusing zswap_pools_lock. But the problem is that it's initialized only when zswap enabled, which causes bug if zswap_memcg_offline_cleanup() called without zswap enabled. Fix it by using DEFINE_SPINLOCK() to statically initialize them and define them as multiple static variables to keep in consistent with the existing global variables in zswap. Link: https://lkml.kernel.org/r/20240305075345.1493214-1-chengming.zhou@linux.dev Fixes: bf9b7df23cb3 ("mm/zswap: global lru and shrinker shared by all zswap_pools") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202403051008.a8cf8a94-lkp@intel.com Signed-off-by: Chengming Zhou Acked-by: Johannes Weiner Cc: Nhat Pham Cc: Yosry Ahmed Signed-off-by: Andrew Morton --- mm/zswap.c | 77 +++++++++++++++++++++++++++++++------------------------------- 1 file changed, 38 insertions(+), 39 deletions(-) (limited to 'mm') diff --git a/mm/zswap.c b/mm/zswap.c index da90933c6d20..9a3237752082 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -180,15 +180,16 @@ struct zswap_pool { char tfm_name[CRYPTO_MAX_ALG_NAME]; }; -static struct { - struct list_lru list_lru; - atomic_t nr_stored; - struct shrinker *shrinker; - struct work_struct shrink_work; - struct mem_cgroup *next_shrink; - /* The lock protects next_shrink. */ - spinlock_t shrink_lock; -} zswap; +/* Global LRU lists shared by all zswap pools. */ +static struct list_lru zswap_list_lru; +/* counter of pages stored in all zswap pools. */ +static atomic_t zswap_nr_stored = ATOMIC_INIT(0); + +/* The lock protects zswap_next_shrink updates. */ +static DEFINE_SPINLOCK(zswap_shrink_lock); +static struct mem_cgroup *zswap_next_shrink; +static struct work_struct zswap_shrink_work; +static struct shrinker *zswap_shrinker; /* * struct zswap_entry @@ -798,10 +799,10 @@ void zswap_folio_swapin(struct folio *folio) void zswap_memcg_offline_cleanup(struct mem_cgroup *memcg) { /* lock out zswap shrinker walking memcg tree */ - spin_lock(&zswap.shrink_lock); - if (zswap.next_shrink == memcg) - zswap.next_shrink = mem_cgroup_iter(NULL, zswap.next_shrink, NULL); - spin_unlock(&zswap.shrink_lock); + spin_lock(&zswap_shrink_lock); + if (zswap_next_shrink == memcg) + zswap_next_shrink = mem_cgroup_iter(NULL, zswap_next_shrink, NULL); + spin_unlock(&zswap_shrink_lock); } /********************************* @@ -900,9 +901,9 @@ static void zswap_entry_free(struct zswap_entry *entry) if (!entry->length) atomic_dec(&zswap_same_filled_pages); else { - zswap_lru_del(&zswap.list_lru, entry); + zswap_lru_del(&zswap_list_lru, entry); zpool_free(zswap_find_zpool(entry), entry->handle); - atomic_dec(&zswap.nr_stored); + atomic_dec(&zswap_nr_stored); zswap_pool_put(entry->pool); } if (entry->objcg) { @@ -1274,7 +1275,7 @@ static unsigned long zswap_shrinker_scan(struct shrinker *shrinker, nr_protected = atomic_long_read(&lruvec->zswap_lruvec_state.nr_zswap_protected); - lru_size = list_lru_shrink_count(&zswap.list_lru, sc); + lru_size = list_lru_shrink_count(&zswap_list_lru, sc); /* * Abort if we are shrinking into the protected region. @@ -1291,7 +1292,7 @@ static unsigned long zswap_shrinker_scan(struct shrinker *shrinker, return SHRINK_STOP; } - shrink_ret = list_lru_shrink_walk(&zswap.list_lru, sc, &shrink_memcg_cb, + shrink_ret = list_lru_shrink_walk(&zswap_list_lru, sc, &shrink_memcg_cb, &encountered_page_in_swapcache); if (encountered_page_in_swapcache) @@ -1317,7 +1318,7 @@ static unsigned long zswap_shrinker_count(struct shrinker *shrinker, #else /* use pool stats instead of memcg stats */ nr_backing = zswap_pool_total_size >> PAGE_SHIFT; - nr_stored = atomic_read(&zswap.nr_stored); + nr_stored = atomic_read(&zswap_nr_stored); #endif if (!nr_stored) @@ -1325,7 +1326,7 @@ static unsigned long zswap_shrinker_count(struct shrinker *shrinker, nr_protected = atomic_long_read(&lruvec->zswap_lruvec_state.nr_zswap_protected); - nr_freeable = list_lru_shrink_count(&zswap.list_lru, sc); + nr_freeable = list_lru_shrink_count(&zswap_list_lru, sc); /* * Subtract the lru size by an estimate of the number of pages * that should be protected. @@ -1374,7 +1375,7 @@ static int shrink_memcg(struct mem_cgroup *memcg) for_each_node_state(nid, N_NORMAL_MEMORY) { unsigned long nr_to_walk = 1; - shrunk += list_lru_walk_one(&zswap.list_lru, nid, memcg, + shrunk += list_lru_walk_one(&zswap_list_lru, nid, memcg, &shrink_memcg_cb, NULL, &nr_to_walk); } return shrunk ? 0 : -EAGAIN; @@ -1387,9 +1388,9 @@ static void shrink_worker(struct work_struct *w) /* global reclaim will select cgroup in a round-robin fashion. */ do { - spin_lock(&zswap.shrink_lock); - zswap.next_shrink = mem_cgroup_iter(NULL, zswap.next_shrink, NULL); - memcg = zswap.next_shrink; + spin_lock(&zswap_shrink_lock); + zswap_next_shrink = mem_cgroup_iter(NULL, zswap_next_shrink, NULL); + memcg = zswap_next_shrink; /* * We need to retry if we have gone through a full round trip, or if we @@ -1403,7 +1404,7 @@ static void shrink_worker(struct work_struct *w) * memcg is not killed when we are reclaiming. */ if (!memcg) { - spin_unlock(&zswap.shrink_lock); + spin_unlock(&zswap_shrink_lock); if (++failures == MAX_RECLAIM_RETRIES) break; @@ -1413,15 +1414,15 @@ static void shrink_worker(struct work_struct *w) if (!mem_cgroup_tryget_online(memcg)) { /* drop the reference from mem_cgroup_iter() */ mem_cgroup_iter_break(NULL, memcg); - zswap.next_shrink = NULL; - spin_unlock(&zswap.shrink_lock); + zswap_next_shrink = NULL; + spin_unlock(&zswap_shrink_lock); if (++failures == MAX_RECLAIM_RETRIES) break; goto resched; } - spin_unlock(&zswap.shrink_lock); + spin_unlock(&zswap_shrink_lock); ret = shrink_memcg(memcg); /* drop the extra reference */ @@ -1542,7 +1543,7 @@ bool zswap_store(struct folio *folio) if (objcg) { memcg = get_mem_cgroup_from_objcg(objcg); - if (memcg_list_lru_alloc(memcg, &zswap.list_lru, GFP_KERNEL)) { + if (memcg_list_lru_alloc(memcg, &zswap_list_lru, GFP_KERNEL)) { mem_cgroup_put(memcg); goto put_pool; } @@ -1573,8 +1574,8 @@ insert_entry: } if (entry->length) { INIT_LIST_HEAD(&entry->lru); - zswap_lru_add(&zswap.list_lru, entry); - atomic_inc(&zswap.nr_stored); + zswap_lru_add(&zswap_list_lru, entry); + atomic_inc(&zswap_nr_stored); } spin_unlock(&tree->lock); @@ -1606,7 +1607,7 @@ check_old: return false; shrink: - queue_work(shrink_wq, &zswap.shrink_work); + queue_work(shrink_wq, &zswap_shrink_work); goto reject; } @@ -1773,16 +1774,14 @@ static int zswap_setup(void) if (!shrink_wq) goto shrink_wq_fail; - zswap.shrinker = zswap_alloc_shrinker(); - if (!zswap.shrinker) + zswap_shrinker = zswap_alloc_shrinker(); + if (!zswap_shrinker) goto shrinker_fail; - if (list_lru_init_memcg(&zswap.list_lru, zswap.shrinker)) + if (list_lru_init_memcg(&zswap_list_lru, zswap_shrinker)) goto lru_fail; - shrinker_register(zswap.shrinker); + shrinker_register(zswap_shrinker); - INIT_WORK(&zswap.shrink_work, shrink_worker); - atomic_set(&zswap.nr_stored, 0); - spin_lock_init(&zswap.shrink_lock); + INIT_WORK(&zswap_shrink_work, shrink_worker); pool = __zswap_pool_create_fallback(); if (pool) { @@ -1801,7 +1800,7 @@ static int zswap_setup(void) return 0; lru_fail: - shrinker_free(zswap.shrinker); + shrinker_free(zswap_shrinker); shrinker_fail: destroy_workqueue(shrink_wq); shrink_wq_fail: -- cgit