(2013/02/08 22:07), Glauber Costa wrote:
> When a new memcg is created, we need to open up room for its descriptors
> in all of the list_lrus that are marked per-memcg. The process is quite
> similar to the one we are using for the kmem caches: we initialize the
> new structures in an array indexed by kmemcg_id, and grow the array if
> needed. Key data like the size of the array will be shared between the
> kmem cache code and the list_lru code (they basically describe the same
> thing)
>
> Signed-off-by: Glauber Costa <glommer@xxxxxxxxxxxxx>
> Cc: Dave Chinner <dchinner@xxxxxxxxxx>
> Cc: Mel Gorman <mgorman@xxxxxxx>
> Cc: Rik van Riel <riel@xxxxxxxxxx>
> Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
> Cc: Michal Hocko <mhocko@xxxxxxx>
> Cc: Hugh Dickins <hughd@xxxxxxxxxx>
> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> ---
> include/linux/list_lru.h | 47 +++++++++++++++++
> include/linux/memcontrol.h | 6 +++
> lib/list_lru.c | 115 +++++++++++++++++++++++++++++++++++++---
> mm/memcontrol.c | 128 ++++++++++++++++++++++++++++++++++++++++++---
> mm/slab_common.c | 1 -
> 5 files changed, 283 insertions(+), 14 deletions(-)
>
> diff --git a/include/linux/list_lru.h b/include/linux/list_lru.h
> index 02796da..370b989 100644
> --- a/include/linux/list_lru.h
> +++ b/include/linux/list_lru.h
> @@ -16,11 +16,58 @@ struct list_lru_node {
> long nr_items;
> } ____cacheline_aligned_in_smp;
>
> +struct list_lru_array {
> + struct list_lru_node node[1];
> +};
size is up to nr_node_ids ?
> +
> struct list_lru {
> + struct list_head lrus;
> struct list_lru_node node[MAX_NUMNODES];
> nodemask_t active_nodes;
> +#ifdef CONFIG_MEMCG_KMEM
> + struct list_lru_array **memcg_lrus;
> +#endif
> };
size is up to memcg_limited_groups_array_size ?
>
> +struct mem_cgroup;
> +#ifdef CONFIG_MEMCG_KMEM
> +/*
> + * We will reuse the last bit of the pointer to tell the lru subsystem that
> + * this particular lru should be replicated when a memcg comes in.
> + */
> +static inline void lru_memcg_enable(struct list_lru *lru)
> +{
> + lru->memcg_lrus = (void *)0x1ULL;
> +}
> +
This "enable" is not used in this patch itself, right ?
> +/*
> + * This will return true if we have already allocated and assignment a memcg
> + * pointer set to the LRU. Therefore, we need to mask the first bit out
> + */
> +static inline bool lru_memcg_is_assigned(struct list_lru *lru)
> +{
> + return (unsigned long)lru->memcg_lrus & ~0x1ULL;
> +}
> +
> +struct list_lru_array *lru_alloc_array(void);
> +int memcg_update_all_lrus(unsigned long num);
> +void list_lru_destroy(struct list_lru *lru);
> +void list_lru_destroy_memcg(struct mem_cgroup *memcg);
> +#else
> +static inline void lru_memcg_enable(struct list_lru *lru)
> +{
> +}
> +
> +static inline bool lru_memcg_is_assigned(struct list_lru *lru)
> +{
> + return false;
> +}
> +
> +static inline void list_lru_destroy(struct list_lru *lru)
> +{
> +}
> +#endif
> +
> int list_lru_init(struct list_lru *lru);
> int list_lru_add(struct list_lru *lru, struct list_head *item);
> int list_lru_del(struct list_lru *lru, struct list_head *item);
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index b7de557..f9558d0 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -23,6 +23,7 @@
> #include <linux/vm_event_item.h>
> #include <linux/hardirq.h>
> #include <linux/jump_label.h>
> +#include <linux/list_lru.h>
>
> struct mem_cgroup;
> struct page_cgroup;
> @@ -475,6 +476,11 @@ void memcg_update_array_size(int num_groups);
> struct kmem_cache *
> __memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp);
>
> +int memcg_new_lru(struct list_lru *lru);
> +
> +int memcg_kmem_update_lru_size(struct list_lru *lru, int num_groups,
> + bool new_lru);
> +
> void mem_cgroup_destroy_cache(struct kmem_cache *cachep);
> void kmem_cache_destroy_memcg_children(struct kmem_cache *s);
>
> diff --git a/lib/list_lru.c b/lib/list_lru.c
> index 0f08ed6..3b0e89d 100644
> --- a/lib/list_lru.c
> +++ b/lib/list_lru.c
> @@ -8,6 +8,7 @@
> #include <linux/module.h>
> #include <linux/mm.h>
> #include <linux/list_lru.h>
> +#include <linux/memcontrol.h>
>
> int
> list_lru_add(
> @@ -184,18 +185,118 @@ list_lru_dispose_all(
> return total;
> }
>
> -int
> -list_lru_init(
> - struct list_lru *lru)
> +/*
> + * This protects the list of all LRU in the system. One only needs
> + * to take when registering an LRU, or when duplicating the list of lrus.
> + * Transversing an LRU can and should be done outside the lock
> + */
> +static DEFINE_MUTEX(all_lrus_mutex);
> +static LIST_HEAD(all_lrus);
> +
> +static void list_lru_init_one(struct list_lru_node *lru)
> +{
> + spin_lock_init(&lru->lock);
> + INIT_LIST_HEAD(&lru->list);
> + lru->nr_items = 0;
> +}
> +
> +struct list_lru_array *lru_alloc_array(void)
> +{
> + struct list_lru_array *lru_array;
> + int i;
> +
> + lru_array = kzalloc(nr_node_ids * sizeof(struct list_lru_node),
> + GFP_KERNEL);
> + if (!lru_array)
> + return NULL;
> +
> + for (i = 0; i < nr_node_ids ; i++)
> + list_lru_init_one(&lru_array->node[i]);
> +
> + return lru_array;
> +}
> +
> +int __list_lru_init(struct list_lru *lru)
> {
> int i;
>
> nodes_clear(lru->active_nodes);
> - for (i = 0; i < MAX_NUMNODES; i++) {
> - spin_lock_init(&lru->node[i].lock);
> - INIT_LIST_HEAD(&lru->node[i].list);
> - lru->node[i].nr_items = 0;
> + for (i = 0; i < MAX_NUMNODES; i++)
> + list_lru_init_one(&lru->node[i]);
Hmm. lru_list is up to MAX_NUMNODES, your new one is up to nr_node_ids...
> +
> + return 0;
> +}
> +
> +#ifdef CONFIG_MEMCG_KMEM
> +static int memcg_init_lru(struct list_lru *lru)
> +{
> + int ret;
> +
> + if (!lru->memcg_lrus)
> + return 0;
> +
> + INIT_LIST_HEAD(&lru->lrus);
> + mutex_lock(&all_lrus_mutex);
> + list_add(&lru->lrus, &all_lrus);
> + ret = memcg_new_lru(lru);
> + mutex_unlock(&all_lrus_mutex);
> + return ret;
> +}
only writer takes this mutex ?
> +
> +int memcg_update_all_lrus(unsigned long num)
> +{
> + int ret = 0;
> + struct list_lru *lru;
> +
> + mutex_lock(&all_lrus_mutex);
> + list_for_each_entry(lru, &all_lrus, lrus) {
> + if (!lru->memcg_lrus)
> + continue;
> +
> + ret = memcg_kmem_update_lru_size(lru, num, false);
> + if (ret)
> + goto out;
> + }
> +out:
> + mutex_unlock(&all_lrus_mutex);
> + return ret;
> +}
> +
> +void list_lru_destroy(struct list_lru *lru)
> +{
> + if (!lru->memcg_lrus)
> + return;
> +
> + mutex_lock(&all_lrus_mutex);
> + list_del(&lru->lrus);
> + mutex_unlock(&all_lrus_mutex);
> +}
> +
> +void list_lru_destroy_memcg(struct mem_cgroup *memcg)
> +{
> + struct list_lru *lru;
> + mutex_lock(&all_lrus_mutex);
> + list_for_each_entry(lru, &all_lrus, lrus) {
> + lru->memcg_lrus[memcg_cache_id(memcg)] = NULL;
> + /* everybody must beaware that this memcg is no longer valid */
Hm, the object pointed by this array entry will be freed by some other func ?
> + wmb();
> }
> + mutex_unlock(&all_lrus_mutex);
> +}
> +#else
> +static int memcg_init_lru(struct list_lru *lru)
> +{
> return 0;
> }
> +#endif
> +
> +int list_lru_init(struct list_lru *lru)
> +{
> + int ret;
> + ret = __list_lru_init(lru);
> + if (ret)
> + return ret;
> +
> + return memcg_init_lru(lru);
> +}
> EXPORT_SYMBOL_GPL(list_lru_init);
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index b1d4dfa..b9e1941 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3032,16 +3032,30 @@ int memcg_update_cache_sizes(struct mem_cgroup *memcg)
> memcg_kmem_set_activated(memcg);
>
> ret = memcg_update_all_caches(num+1);
> - if (ret) {
> - ida_simple_remove(&kmem_limited_groups, num);
> - memcg_kmem_clear_activated(memcg);
> - return ret;
> - }
> + if (ret)
> + goto out;
> +
> + /*
> + * We should make sure that the array size is not updated until we are
> + * done; otherwise we have no easy way to know whether or not we should
> + * grow the array.
> + */
> + ret = memcg_update_all_lrus(num + 1);
> + if (ret)
> + goto out;
>
> memcg->kmemcg_id = num;
> +
> + memcg_update_array_size(num + 1);
> +
> INIT_LIST_HEAD(&memcg->memcg_slab_caches);
> mutex_init(&memcg->slab_caches_mutex);
> +
> return 0;
> +out:
> + ida_simple_remove(&kmem_limited_groups, num);
> + memcg_kmem_clear_activated(memcg);
> + return ret;
> }
>
> static size_t memcg_caches_array_size(int num_groups)
> @@ -3121,6 +3135,106 @@ int memcg_update_cache_size(struct kmem_cache *s, int num_groups)
> return 0;
> }
>
> +/*
> + * memcg_kmem_update_lru_size - fill in kmemcg info into a list_lru
> + *
> + * @lru: the lru we are operating with
> + * @num_groups: how many kmem-limited cgroups we have
> + * @new_lru: true if this is a new_lru being created, false if this
> + * was triggered from the memcg side
> + *
> + * Returns 0 on success, and an error code otherwise.
> + *
> + * This function can be called either when a new kmem-limited memcg appears,
> + * or when a new list_lru is created. The work is roughly the same in two cases,
> + * but in the later we never have to expand the array size.
> + *
> + * This is always protected by the all_lrus_mutex from the list_lru side.
> + */
> +int memcg_kmem_update_lru_size(struct list_lru *lru, int num_groups,
> + bool new_lru)
> +{
> + struct list_lru_array **new_lru_array;
> + struct list_lru_array *lru_array;
> +
Both are named as array ...confusing ;)
> + lru_array = lru_alloc_array();
> + if (!lru_array)
> + return -ENOMEM;
> +
> + /* need some fucked up locking around the list acquisition */
> + if ((num_groups > memcg_limited_groups_array_size) || new_lru) {
> + int i;
> + struct list_lru_array **old_array;
> + size_t size = memcg_caches_array_size(num_groups);
> +
> + new_lru_array = kzalloc(size * sizeof(void *), GFP_KERNEL);
> + if (!new_lru_array) {
> + kfree(lru_array);
> + return -ENOMEM;
> + }
> +
> + for (i = 0; i < memcg_limited_groups_array_size; i++) {
> + if (!lru_memcg_is_assigned(lru) || lru->memcg_lrus[i])
> + continue;
> + new_lru_array[i] = lru->memcg_lrus[i];
> + }
> +
> + old_array = lru->memcg_lrus;
> + lru->memcg_lrus = new_lru_array;
> + /*
> + * We don't need a barrier here because we are just copying
> + * information over. Anybody operating in memcg_lrus will
> + * either follow the new array or the old one and they contain
> + * exactly the same information. The new space in the end is
> + * always empty anyway.
> + *
> + * We do have to make sure that no more users of the old
> + * memcg_lrus array exist before we free, and this is achieved
> + * by the synchronize_lru below.
> + */
> + if (lru_memcg_is_assigned(lru)) {
> + synchronize_rcu();
> + kfree(old_array);
> + }
> +
> + }
> +
> + if (lru_memcg_is_assigned(lru)) {
> + lru->memcg_lrus[num_groups - 1] = lru_array;
Can't this pointer already set ?
> + /*
> + * Here we do need the barrier, because of the state transition
> + * implied by the assignment of the array. All users should be
> + * able to see it
> + */
> + wmb();
> + }
> +
> + return 0;
> +
> +}
> +
> +int memcg_new_lru(struct list_lru *lru)
> +{
> + struct mem_cgroup *iter;
> +
> + if (!memcg_kmem_enabled())
> + return 0;
> +
> + for_each_mem_cgroup(iter) {
> + int ret;
> + int memcg_id = memcg_cache_id(iter);
> + if (memcg_id < 0)
> + continue;
> +
> + ret = memcg_kmem_update_lru_size(lru, memcg_id + 1, true);
> + if (ret) {
> + mem_cgroup_iter_break(root_mem_cgroup, iter);
> + return ret;
> + }
> + }
> + return 0;
> +}
> +
> int memcg_register_cache(struct mem_cgroup *memcg, struct kmem_cache *s,
> struct kmem_cache *root_cache)
> {
> @@ -5914,8 +6028,10 @@ static void kmem_cgroup_destroy(struct mem_cgroup *memcg)
> * possible that the charges went down to 0 between mark_dead and the
> * res_counter read, so in that case, we don't need the put
> */
> - if (memcg_kmem_test_and_clear_dead(memcg))
> + if (memcg_kmem_test_and_clear_dead(memcg)) {
> + list_lru_destroy_memcg(memcg);
> mem_cgroup_put(memcg);
> + }
> }
> #else
> static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> indek
x 3f3cd97..2470d11 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -102,7 +102,6 @@ int memcg_update_all_caches(int num_memcgs)
> goto out;
> }
>
> - memcg_update_array_size(num_memcgs);
> out:
> mutex_unlock(&slab_mutex);
> return ret;
>
Thanks,
-Kame
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