To make list_lru memcg aware, we need all list_lrus to be kept on a list protected by a mutex, so that we could sleep while walking over the list.
Therefore after this change list_lru_destroy may sleep. Fortunately, there is the only user that calls it from an atomic context - it's put_super - and we can easily fix it by calling list_lru_destroy before put_super in destroy_locked_super - anyway we don't longer need lrus by that time. Another point that should be noted is that list_lru_destroy is allowed to be called on an uninitialized zeroed-out object, in which case it is a no-op. Before this patch this was guaranteed by kfree, but now we need an explicit check there. Signed-off-by: Vladimir Davydov <[email protected]> --- fs/super.c | 8 ++++++++ include/linux/list_lru.h | 3 +++ mm/list_lru.c | 34 ++++++++++++++++++++++++++++++++++ 3 files changed, 45 insertions(+) diff --git a/fs/super.c b/fs/super.c index a2b735a42e74..b027849d92d2 100644 --- a/fs/super.c +++ b/fs/super.c @@ -282,6 +282,14 @@ void deactivate_locked_super(struct super_block *s) unregister_shrinker(&s->s_shrink); fs->kill_sb(s); + /* + * Since list_lru_destroy() may sleep, we cannot call it from + * put_super(), where we hold the sb_lock. Therefore we destroy + * the lru lists right now. + */ + list_lru_destroy(&s->s_dentry_lru); + list_lru_destroy(&s->s_inode_lru); + put_filesystem(fs); put_super(s); } else { diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h index 53c1d6b78270..ee9486ac0621 100644 --- a/include/linux/list_lru.h +++ b/include/linux/list_lru.h @@ -31,6 +31,9 @@ struct list_lru_node { struct list_lru { struct list_lru_node *node; +#ifdef CONFIG_MEMCG_KMEM + struct list_head list; +#endif }; void list_lru_destroy(struct list_lru *lru); diff --git a/mm/list_lru.c b/mm/list_lru.c index 07e198c77888..a9021cb3ccde 100644 --- a/mm/list_lru.c +++ b/mm/list_lru.c @@ -9,6 +9,34 @@ #include <linux/mm.h> #include <linux/list_lru.h> #include <linux/slab.h> +#include <linux/mutex.h> + +#ifdef CONFIG_MEMCG_KMEM +static LIST_HEAD(list_lrus); +static DEFINE_MUTEX(list_lrus_mutex); + +static void list_lru_register(struct list_lru *lru) +{ + mutex_lock(&list_lrus_mutex); + list_add(&lru->list, &list_lrus); + mutex_unlock(&list_lrus_mutex); +} + +static void list_lru_unregister(struct list_lru *lru) +{ + mutex_lock(&list_lrus_mutex); + list_del(&lru->list); + mutex_unlock(&list_lrus_mutex); +} +#else +static void list_lru_register(struct list_lru *lru) +{ +} + +static void list_lru_unregister(struct list_lru *lru) +{ +} +#endif /* CONFIG_MEMCG_KMEM */ bool list_lru_add(struct list_lru *lru, struct list_head *item) { @@ -137,12 +165,18 @@ int list_lru_init_key(struct list_lru *lru, struct lock_class_key *key) INIT_LIST_HEAD(&lru->node[i].list); lru->node[i].nr_items = 0; } + list_lru_register(lru); return 0; } EXPORT_SYMBOL_GPL(list_lru_init_key); void list_lru_destroy(struct list_lru *lru) { + /* Already destroyed or not yet initialized? */ + if (!lru->node) + return; + list_lru_unregister(lru); kfree(lru->node); + lru->node = NULL; } EXPORT_SYMBOL_GPL(list_lru_destroy); -- 1.7.10.4 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
