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mm/zswap: global lru and shrinker shared by all zswap_pools fix 

Commit bf9b7df23c ("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: bf9b7df23c ("mm/zswap: global lru and shrinker shared by all zswap_pools")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202403051008.a8cf8a94-lkp@intel.com
Signed-off-by: Chengming Zhou <chengming.zhou@linux.dev>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Chengming Zhou 2024-03-05 07:53:45 +00:00 committed by Andrew Morton
parent 5aa598a72e
commit e35606e416
1 changed files with 38 additions and 39 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

77
mm/zswap.c
View File

@ -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: