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SubjectRe: [v6 PATCH 02/11] mm: vmscan: consolidate shrinker_maps handling code
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On 03.02.2021 20:20, Yang Shi wrote:
> The shrinker map management is not purely memcg specific, it is at the intersection
> between memory cgroup and shrinkers. It's allocation and assignment of a structure,
> and the only memcg bit is the map is being stored in a memcg structure. So move the
> shrinker_maps handling code into vmscan.c for tighter integration with shrinker code,
> and remove the "memcg_" prefix. There is no functional change.
>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
> Signed-off-by: Yang Shi <shy828301@gmail.com>

Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>

> ---
> include/linux/memcontrol.h | 11 ++--
> mm/huge_memory.c | 4 +-
> mm/list_lru.c | 6 +-
> mm/memcontrol.c | 129 +-----------------------------------
> mm/vmscan.c | 131 ++++++++++++++++++++++++++++++++++++-
> 5 files changed, 141 insertions(+), 140 deletions(-)
>
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index eeb0b52203e9..1739f17e0939 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -1581,10 +1581,9 @@ static inline bool mem_cgroup_under_socket_pressure(struct mem_cgroup *memcg)
> return false;
> }
>
> -extern int memcg_expand_shrinker_maps(int new_id);
> -
> -extern void memcg_set_shrinker_bit(struct mem_cgroup *memcg,
> - int nid, int shrinker_id);
> +int alloc_shrinker_maps(struct mem_cgroup *memcg);
> +void free_shrinker_maps(struct mem_cgroup *memcg);
> +void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id);
> #else
> #define mem_cgroup_sockets_enabled 0
> static inline void mem_cgroup_sk_alloc(struct sock *sk) { };
> @@ -1594,8 +1593,8 @@ static inline bool mem_cgroup_under_socket_pressure(struct mem_cgroup *memcg)
> return false;
> }
>
> -static inline void memcg_set_shrinker_bit(struct mem_cgroup *memcg,
> - int nid, int shrinker_id)
> +static inline void set_shrinker_bit(struct mem_cgroup *memcg,
> + int nid, int shrinker_id)
> {
> }
> #endif
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 9237976abe72..05190d7f32ae 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2823,8 +2823,8 @@ void deferred_split_huge_page(struct page *page)
> ds_queue->split_queue_len++;
> #ifdef CONFIG_MEMCG
> if (memcg)
> - memcg_set_shrinker_bit(memcg, page_to_nid(page),
> - deferred_split_shrinker.id);
> + set_shrinker_bit(memcg, page_to_nid(page),
> + deferred_split_shrinker.id);
> #endif
> }
> spin_unlock_irqrestore(&ds_queue->split_queue_lock, flags);
> diff --git a/mm/list_lru.c b/mm/list_lru.c
> index fe230081690b..628030fa5f69 100644
> --- a/mm/list_lru.c
> +++ b/mm/list_lru.c
> @@ -125,8 +125,8 @@ bool list_lru_add(struct list_lru *lru, struct list_head *item)
> list_add_tail(item, &l->list);
> /* Set shrinker bit if the first element was added */
> if (!l->nr_items++)
> - memcg_set_shrinker_bit(memcg, nid,
> - lru_shrinker_id(lru));
> + set_shrinker_bit(memcg, nid,
> + lru_shrinker_id(lru));
> nlru->nr_items++;
> spin_unlock(&nlru->lock);
> return true;
> @@ -548,7 +548,7 @@ static void memcg_drain_list_lru_node(struct list_lru *lru, int nid,
>
> if (src->nr_items) {
> dst->nr_items += src->nr_items;
> - memcg_set_shrinker_bit(dst_memcg, nid, lru_shrinker_id(lru));
> + set_shrinker_bit(dst_memcg, nid, lru_shrinker_id(lru));
> src->nr_items = 0;
> }
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 1bdb93ee8e72..f5c9a0d2160b 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -397,129 +397,6 @@ DEFINE_STATIC_KEY_FALSE(memcg_kmem_enabled_key);
> EXPORT_SYMBOL(memcg_kmem_enabled_key);
> #endif
>
> -static int memcg_shrinker_map_size;
> -static DEFINE_MUTEX(memcg_shrinker_map_mutex);
> -
> -static void memcg_free_shrinker_map_rcu(struct rcu_head *head)
> -{
> - kvfree(container_of(head, struct memcg_shrinker_map, rcu));
> -}
> -
> -static int memcg_expand_one_shrinker_map(struct mem_cgroup *memcg,
> - int size, int old_size)
> -{
> - struct memcg_shrinker_map *new, *old;
> - int nid;
> -
> - lockdep_assert_held(&memcg_shrinker_map_mutex);
> -
> - for_each_node(nid) {
> - old = rcu_dereference_protected(
> - mem_cgroup_nodeinfo(memcg, nid)->shrinker_map, true);
> - /* Not yet online memcg */
> - if (!old)
> - return 0;
> -
> - new = kvmalloc_node(sizeof(*new) + size, GFP_KERNEL, nid);
> - if (!new)
> - return -ENOMEM;
> -
> - /* Set all old bits, clear all new bits */
> - memset(new->map, (int)0xff, old_size);
> - memset((void *)new->map + old_size, 0, size - old_size);
> -
> - rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_map, new);
> - call_rcu(&old->rcu, memcg_free_shrinker_map_rcu);
> - }
> -
> - return 0;
> -}
> -
> -static void memcg_free_shrinker_maps(struct mem_cgroup *memcg)
> -{
> - struct mem_cgroup_per_node *pn;
> - struct memcg_shrinker_map *map;
> - int nid;
> -
> - if (mem_cgroup_is_root(memcg))
> - return;
> -
> - for_each_node(nid) {
> - pn = mem_cgroup_nodeinfo(memcg, nid);
> - map = rcu_dereference_protected(pn->shrinker_map, true);
> - kvfree(map);
> - rcu_assign_pointer(pn->shrinker_map, NULL);
> - }
> -}
> -
> -static int memcg_alloc_shrinker_maps(struct mem_cgroup *memcg)
> -{
> - struct memcg_shrinker_map *map;
> - int nid, size, ret = 0;
> -
> - if (mem_cgroup_is_root(memcg))
> - return 0;
> -
> - mutex_lock(&memcg_shrinker_map_mutex);
> - size = memcg_shrinker_map_size;
> - for_each_node(nid) {
> - map = kvzalloc_node(sizeof(*map) + size, GFP_KERNEL, nid);
> - if (!map) {
> - memcg_free_shrinker_maps(memcg);
> - ret = -ENOMEM;
> - break;
> - }
> - rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_map, map);
> - }
> - mutex_unlock(&memcg_shrinker_map_mutex);
> -
> - return ret;
> -}
> -
> -int memcg_expand_shrinker_maps(int new_id)
> -{
> - int size, old_size, ret = 0;
> - struct mem_cgroup *memcg;
> -
> - size = DIV_ROUND_UP(new_id + 1, BITS_PER_LONG) * sizeof(unsigned long);
> - old_size = memcg_shrinker_map_size;
> - if (size <= old_size)
> - return 0;
> -
> - mutex_lock(&memcg_shrinker_map_mutex);
> - if (!root_mem_cgroup)
> - goto unlock;
> -
> - for_each_mem_cgroup(memcg) {
> - if (mem_cgroup_is_root(memcg))
> - continue;
> - ret = memcg_expand_one_shrinker_map(memcg, size, old_size);
> - if (ret) {
> - mem_cgroup_iter_break(NULL, memcg);
> - goto unlock;
> - }
> - }
> -unlock:
> - if (!ret)
> - memcg_shrinker_map_size = size;
> - mutex_unlock(&memcg_shrinker_map_mutex);
> - return ret;
> -}
> -
> -void memcg_set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id)
> -{
> - if (shrinker_id >= 0 && memcg && !mem_cgroup_is_root(memcg)) {
> - struct memcg_shrinker_map *map;
> -
> - rcu_read_lock();
> - map = rcu_dereference(memcg->nodeinfo[nid]->shrinker_map);
> - /* Pairs with smp mb in shrink_slab() */
> - smp_mb__before_atomic();
> - set_bit(shrinker_id, map->map);
> - rcu_read_unlock();
> - }
> -}
> -
> /**
> * mem_cgroup_css_from_page - css of the memcg associated with a page
> * @page: page of interest
> @@ -5369,11 +5246,11 @@ static int mem_cgroup_css_online(struct cgroup_subsys_state *css)
> struct mem_cgroup *memcg = mem_cgroup_from_css(css);
>
> /*
> - * A memcg must be visible for memcg_expand_shrinker_maps()
> + * A memcg must be visible for expand_shrinker_maps()
> * by the time the maps are allocated. So, we allocate maps
> * here, when for_each_mem_cgroup() can't skip it.
> */
> - if (memcg_alloc_shrinker_maps(memcg)) {
> + if (alloc_shrinker_maps(memcg)) {
> mem_cgroup_id_remove(memcg);
> return -ENOMEM;
> }
> @@ -5437,7 +5314,7 @@ static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
> vmpressure_cleanup(&memcg->vmpressure);
> cancel_work_sync(&memcg->high_work);
> mem_cgroup_remove_from_trees(memcg);
> - memcg_free_shrinker_maps(memcg);
> + free_shrinker_maps(memcg);
> memcg_free_kmem(memcg);
> mem_cgroup_free(memcg);
> }
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index b512dd5e3a1c..96b08c79f18d 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -185,6 +185,131 @@ static LIST_HEAD(shrinker_list);
> static DECLARE_RWSEM(shrinker_rwsem);
>
> #ifdef CONFIG_MEMCG
> +
> +static int memcg_shrinker_map_size;
> +static DEFINE_MUTEX(memcg_shrinker_map_mutex);
> +
> +static void free_shrinker_map_rcu(struct rcu_head *head)
> +{
> + kvfree(container_of(head, struct memcg_shrinker_map, rcu));
> +}
> +
> +static int expand_one_shrinker_map(struct mem_cgroup *memcg,
> + int size, int old_size)
> +{
> + struct memcg_shrinker_map *new, *old;
> + int nid;
> +
> + lockdep_assert_held(&memcg_shrinker_map_mutex);
> +
> + for_each_node(nid) {
> + old = rcu_dereference_protected(
> + mem_cgroup_nodeinfo(memcg, nid)->shrinker_map, true);
> + /* Not yet online memcg */
> + if (!old)
> + return 0;
> +
> + new = kvmalloc_node(sizeof(*new) + size, GFP_KERNEL, nid);
> + if (!new)
> + return -ENOMEM;
> +
> + /* Set all old bits, clear all new bits */
> + memset(new->map, (int)0xff, old_size);
> + memset((void *)new->map + old_size, 0, size - old_size);
> +
> + rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_map, new);
> + call_rcu(&old->rcu, free_shrinker_map_rcu);
> + }
> +
> + return 0;
> +}
> +
> +void free_shrinker_maps(struct mem_cgroup *memcg)
> +{
> + struct mem_cgroup_per_node *pn;
> + struct memcg_shrinker_map *map;
> + int nid;
> +
> + if (mem_cgroup_is_root(memcg))
> + return;
> +
> + for_each_node(nid) {
> + pn = mem_cgroup_nodeinfo(memcg, nid);
> + map = rcu_dereference_protected(pn->shrinker_map, true);
> + kvfree(map);
> + rcu_assign_pointer(pn->shrinker_map, NULL);
> + }
> +}
> +
> +int alloc_shrinker_maps(struct mem_cgroup *memcg)
> +{
> + struct memcg_shrinker_map *map;
> + int nid, size, ret = 0;
> +
> + if (mem_cgroup_is_root(memcg))
> + return 0;
> +
> + mutex_lock(&memcg_shrinker_map_mutex);
> + size = memcg_shrinker_map_size;
> + for_each_node(nid) {
> + map = kvzalloc_node(sizeof(*map) + size, GFP_KERNEL, nid);
> + if (!map) {
> + free_shrinker_maps(memcg);
> + ret = -ENOMEM;
> + break;
> + }
> + rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_map, map);
> + }
> + mutex_unlock(&memcg_shrinker_map_mutex);
> +
> + return ret;
> +}
> +
> +static int expand_shrinker_maps(int new_id)
> +{
> + int size, old_size, ret = 0;
> + struct mem_cgroup *memcg;
> +
> + size = DIV_ROUND_UP(new_id + 1, BITS_PER_LONG) * sizeof(unsigned long);
> + old_size = memcg_shrinker_map_size;
> + if (size <= old_size)
> + return 0;
> +
> + mutex_lock(&memcg_shrinker_map_mutex);
> + if (!root_mem_cgroup)
> + goto unlock;
> +
> + memcg = mem_cgroup_iter(NULL, NULL, NULL);
> + do {
> + if (mem_cgroup_is_root(memcg))
> + continue;
> + ret = expand_one_shrinker_map(memcg, size, old_size);
> + if (ret) {
> + mem_cgroup_iter_break(NULL, memcg);
> + goto unlock;
> + }
> + } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
> +unlock:
> + if (!ret)
> + memcg_shrinker_map_size = size;
> + mutex_unlock(&memcg_shrinker_map_mutex);
> + return ret;
> +}
> +
> +void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id)
> +{
> + if (shrinker_id >= 0 && memcg && !mem_cgroup_is_root(memcg)) {
> + struct memcg_shrinker_map *map;
> +
> + rcu_read_lock();
> + map = rcu_dereference(memcg->nodeinfo[nid]->shrinker_map);
> + /* Pairs with smp mb in shrink_slab() */
> + smp_mb__before_atomic();
> + set_bit(shrinker_id, map->map);
> + rcu_read_unlock();
> + }
> +}
> +
> /*
> * We allow subsystems to populate their shrinker-related
> * LRU lists before register_shrinker_prepared() is called
> @@ -212,7 +337,7 @@ static int prealloc_memcg_shrinker(struct shrinker *shrinker)
> goto unlock;
>
> if (id >= shrinker_nr_max) {
> - if (memcg_expand_shrinker_maps(id)) {
> + if (expand_shrinker_maps(id)) {
> idr_remove(&shrinker_idr, id);
> goto unlock;
> }
> @@ -589,7 +714,7 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
> * case, we invoke the shrinker one more time and reset
> * the bit if it reports that it is not empty anymore.
> * The memory barrier here pairs with the barrier in
> - * memcg_set_shrinker_bit():
> + * set_shrinker_bit():
> *
> * list_lru_add() shrink_slab_memcg()
> * list_add_tail() clear_bit()
> @@ -601,7 +726,7 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
> if (ret == SHRINK_EMPTY)
> ret = 0;
> else
> - memcg_set_shrinker_bit(memcg, nid, i);
> + set_shrinker_bit(memcg, nid, i);
> }
> freed += ret;
>
>

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