diff options
| -rw-r--r-- | include/linux/list_lru.h | 3 | ||||
| -rw-r--r-- | mm/list_lru.c | 67 |
2 files changed, 47 insertions, 23 deletions
diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h index bb8129a3474d..96def9d15b1b 100644 --- a/include/linux/list_lru.h +++ b/include/linux/list_lru.h @@ -32,6 +32,7 @@ struct list_lru_one { }; struct list_lru_memcg { + struct rcu_head rcu; /* array of per cgroup lists, indexed by memcg_cache_id */ struct list_lru_one *lru[0]; }; @@ -43,7 +44,7 @@ struct list_lru_node { struct list_lru_one lru; #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB) /* for cgroup aware lrus points to per cgroup lists, otherwise NULL */ - struct list_lru_memcg *memcg_lrus; + struct list_lru_memcg __rcu *memcg_lrus; #endif long nr_items; } ____cacheline_aligned_in_smp; diff --git a/mm/list_lru.c b/mm/list_lru.c index fd41e969ede5..fcfb6c89ed47 100644 --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -52,14 +52,15 @@ static inline bool list_lru_memcg_aware(struct list_lru *lru) static inline struct list_lru_one * list_lru_from_memcg_idx(struct list_lru_node *nlru, int idx) { + struct list_lru_memcg *memcg_lrus; /* - * The lock protects the array of per cgroup lists from relocation - * (see memcg_update_list_lru_node). + * Either lock or RCU protects the array of per cgroup lists + * from relocation (see memcg_update_list_lru_node). */ - lockdep_assert_held(&nlru->lock); - if (nlru->memcg_lrus && idx >= 0) - return nlru->memcg_lrus->lru[idx]; - + memcg_lrus = rcu_dereference_check(nlru->memcg_lrus, + lockdep_is_held(&nlru->lock)); + if (memcg_lrus && idx >= 0) + return memcg_lrus->lru[idx]; return &nlru->lru; } @@ -168,10 +169,10 @@ static unsigned long __list_lru_count_one(struct list_lru *lru, struct list_lru_one *l; unsigned long count; - spin_lock(&nlru->lock); + rcu_read_lock(); l = list_lru_from_memcg_idx(nlru, memcg_idx); count = l->nr_items; - spin_unlock(&nlru->lock); + rcu_read_unlock(); return count; } @@ -324,24 +325,41 @@ fail: static int memcg_init_list_lru_node(struct list_lru_node *nlru) { + struct list_lru_memcg *memcg_lrus; int size = memcg_nr_cache_ids; - nlru->memcg_lrus = kvmalloc(size * sizeof(void *), GFP_KERNEL); - if (!nlru->memcg_lrus) + memcg_lrus = kvmalloc(sizeof(*memcg_lrus) + + size * sizeof(void *), GFP_KERNEL); + if (!memcg_lrus) return -ENOMEM; - if (__memcg_init_list_lru_node(nlru->memcg_lrus, 0, size)) { - kvfree(nlru->memcg_lrus); + if (__memcg_init_list_lru_node(memcg_lrus, 0, size)) { + kvfree(memcg_lrus); return -ENOMEM; } + RCU_INIT_POINTER(nlru->memcg_lrus, memcg_lrus); return 0; } static void memcg_destroy_list_lru_node(struct list_lru_node *nlru) { - __memcg_destroy_list_lru_node(nlru->memcg_lrus, 0, memcg_nr_cache_ids); - kvfree(nlru->memcg_lrus); + struct list_lru_memcg *memcg_lrus; + /* + * This is called when shrinker has already been unregistered, + * and nobody can use it. So, there is no need to use kvfree_rcu(). + */ + memcg_lrus = rcu_dereference_protected(nlru->memcg_lrus, true); + __memcg_destroy_list_lru_node(memcg_lrus, 0, memcg_nr_cache_ids); + kvfree(memcg_lrus); +} + +static void kvfree_rcu(struct rcu_head *head) +{ + struct list_lru_memcg *mlru; + + mlru = container_of(head, struct list_lru_memcg, rcu); + kvfree(mlru); } static int memcg_update_list_lru_node(struct list_lru_node *nlru, @@ -351,8 +369,9 @@ static int memcg_update_list_lru_node(struct list_lru_node *nlru, BUG_ON(old_size > new_size); - old = nlru->memcg_lrus; - new = kvmalloc(new_size * sizeof(void *), GFP_KERNEL); + old = rcu_dereference_protected(nlru->memcg_lrus, + lockdep_is_held(&list_lrus_mutex)); + new = kvmalloc(sizeof(*new) + new_size * sizeof(void *), GFP_KERNEL); if (!new) return -ENOMEM; @@ -361,29 +380,33 @@ static int memcg_update_list_lru_node(struct list_lru_node *nlru, return -ENOMEM; } - memcpy(new, old, old_size * sizeof(void *)); + memcpy(&new->lru, &old->lru, old_size * sizeof(void *)); /* - * The lock guarantees that we won't race with a reader - * (see list_lru_from_memcg_idx). + * The locking below allows readers that hold nlru->lock avoid taking + * rcu_read_lock (see list_lru_from_memcg_idx). * * Since list_lru_{add,del} may be called under an IRQ-safe lock, * we have to use IRQ-safe primitives here to avoid deadlock. */ spin_lock_irq(&nlru->lock); - nlru->memcg_lrus = new; + rcu_assign_pointer(nlru->memcg_lrus, new); spin_unlock_irq(&nlru->lock); - kvfree(old); + call_rcu(&old->rcu, kvfree_rcu); return 0; } static void memcg_cancel_update_list_lru_node(struct list_lru_node *nlru, int old_size, int new_size) { + struct list_lru_memcg *memcg_lrus; + + memcg_lrus = rcu_dereference_protected(nlru->memcg_lrus, + lockdep_is_held(&list_lrus_mutex)); /* do not bother shrinking the array back to the old size, because we * cannot handle allocation failures here */ - __memcg_destroy_list_lru_node(nlru->memcg_lrus, old_size, new_size); + __memcg_destroy_list_lru_node(memcg_lrus, old_size, new_size); } static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware) |