diff mbox series

[v5,02/11] mm: vmscan: consolidate shrinker_maps handling code

Message ID 20210127233345.339910-3-shy828301@gmail.com (mailing list archive)
State New
Headers show
Series Make shrinker's nr_deferred memcg aware | expand

Commit Message

Yang Shi Jan. 27, 2021, 11:33 p.m. UTC
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.

Signed-off-by: Yang Shi <shy828301@gmail.com>
---
 include/linux/memcontrol.h |  12 ++--
 mm/huge_memory.c           |   4 +-
 mm/list_lru.c              |   6 +-
 mm/memcontrol.c            | 130 +------------------------------------
 mm/vmscan.c                | 130 ++++++++++++++++++++++++++++++++++++-
 5 files changed, 142 insertions(+), 140 deletions(-)

Comments

Vlastimil Babka Jan. 28, 2021, 4:10 p.m. UTC | #1
On 1/28/21 12:33 AM, 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.
> 
> Signed-off-by: Yang Shi <shy828301@gmail.com>

Acked-by: Vlastimil Babka <vbabka@suse.cz>

Nits below:

> @@ -1581,10 +1581,10 @@ 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);
> +extern int alloc_shrinker_maps(struct mem_cgroup *memcg);
> +extern void free_shrinker_maps(struct mem_cgroup *memcg);
> +extern void set_shrinker_bit(struct mem_cgroup *memcg,
> +			     int nid, int shrinker_id);

"extern" is unnecessary and people seem to be removing them nowadays when
touching the code

>  /*
>   * We allow subsystems to populate their shrinker-related
>   * LRU lists before register_shrinker_prepared() is called
> @@ -212,7 +338,7 @@ 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;
>  		}
> @@ -601,7 +727,7 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,

Above this is a comment about barriers in memcg_set_shrinker_bit() that should
be updated.

>  			if (ret == SHRINK_EMPTY)
>  				ret = 0;
>  			else
> -				memcg_set_shrinker_bit(memcg, nid, i);
> +				set_shrinker_bit(memcg, nid, i);
>  		}
>  		freed += ret;
>  
>
Yang Shi Jan. 28, 2021, 9:16 p.m. UTC | #2
On Thu, Jan 28, 2021 at 8:10 AM Vlastimil Babka <vbabka@suse.cz> wrote:
>
> On 1/28/21 12:33 AM, 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.
> >
> > Signed-off-by: Yang Shi <shy828301@gmail.com>
>
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
>
> Nits below:
>
> > @@ -1581,10 +1581,10 @@ 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);
> > +extern int alloc_shrinker_maps(struct mem_cgroup *memcg);
> > +extern void free_shrinker_maps(struct mem_cgroup *memcg);
> > +extern void set_shrinker_bit(struct mem_cgroup *memcg,
> > +                          int nid, int shrinker_id);
>
> "extern" is unnecessary and people seem to be removing them nowadays when
> touching the code

OK, will fix in v6.

>
> >  /*
> >   * We allow subsystems to populate their shrinker-related
> >   * LRU lists before register_shrinker_prepared() is called
> > @@ -212,7 +338,7 @@ 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;
> >               }
> > @@ -601,7 +727,7 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
>
> Above this is a comment about barriers in memcg_set_shrinker_bit() that should
> be updated.

Thanks for catching this. Will fix in v6.

>
> >                       if (ret == SHRINK_EMPTY)
> >                               ret = 0;
> >                       else
> > -                             memcg_set_shrinker_bit(memcg, nid, i);
> > +                             set_shrinker_bit(memcg, nid, i);
> >               }
> >               freed += ret;
> >
> >
>
Kirill Tkhai Jan. 29, 2021, 2:33 p.m. UTC | #3
On 28.01.2021 02:33, 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.
> 
> Signed-off-by: Yang Shi <shy828301@gmail.com>
> ---
>  include/linux/memcontrol.h |  12 ++--
>  mm/huge_memory.c           |   4 +-
>  mm/list_lru.c              |   6 +-
>  mm/memcontrol.c            | 130 +------------------------------------
>  mm/vmscan.c                | 130 ++++++++++++++++++++++++++++++++++++-
>  5 files changed, 142 insertions(+), 140 deletions(-)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index eeb0b52203e9..0ee2924991fb 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -1581,10 +1581,10 @@ 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);
> +extern int alloc_shrinker_maps(struct mem_cgroup *memcg);
> +extern void free_shrinker_maps(struct mem_cgroup *memcg);
> +extern 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 +1594,8 @@ 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 e2de77b5bcc2..f5c9a0d2160b 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -397,130 +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);
> -		if (map)
> -			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
> @@ -5370,11 +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;
>  	}
> @@ -5438,7 +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..d950cead66ca 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -185,6 +185,132 @@ 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);
> +		if (map)
> +			kvfree(map);

We should to forget about below patch and kill "if (map)" check here:

https://lore.kernel.org/linux-mm/1611216029-34397-1-git-send-email-abaci-bugfix@linux.alibaba.com/

> +		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 +338,7 @@ 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;
>  		}
> @@ -601,7 +727,7 @@ 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;
>  
>
Yang Shi Jan. 29, 2021, 5:11 p.m. UTC | #4
On Fri, Jan 29, 2021 at 6:34 AM Kirill Tkhai <ktkhai@virtuozzo.com> wrote:
>
> On 28.01.2021 02:33, 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.
> >
> > Signed-off-by: Yang Shi <shy828301@gmail.com>
> > ---
> >  include/linux/memcontrol.h |  12 ++--
> >  mm/huge_memory.c           |   4 +-
> >  mm/list_lru.c              |   6 +-
> >  mm/memcontrol.c            | 130 +------------------------------------
> >  mm/vmscan.c                | 130 ++++++++++++++++++++++++++++++++++++-
> >  5 files changed, 142 insertions(+), 140 deletions(-)
> >
> > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> > index eeb0b52203e9..0ee2924991fb 100644
> > --- a/include/linux/memcontrol.h
> > +++ b/include/linux/memcontrol.h
> > @@ -1581,10 +1581,10 @@ 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);
> > +extern int alloc_shrinker_maps(struct mem_cgroup *memcg);
> > +extern void free_shrinker_maps(struct mem_cgroup *memcg);
> > +extern 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 +1594,8 @@ 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 e2de77b5bcc2..f5c9a0d2160b 100644
> > --- a/mm/memcontrol.c
> > +++ b/mm/memcontrol.c
> > @@ -397,130 +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);
> > -             if (map)
> > -                     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
> > @@ -5370,11 +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;
> >       }
> > @@ -5438,7 +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..d950cead66ca 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -185,6 +185,132 @@ 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);
> > +             if (map)
> > +                     kvfree(map);
>
> We should to forget about below patch and kill "if (map)" check here:
>
> https://lore.kernel.org/linux-mm/1611216029-34397-1-git-send-email-abaci-bugfix@linux.alibaba.com/

Aha, thanks for reminding me. I didn't notice that patch. It seems it
has been in the -mm tree. Will rebase on top of that patch.

>
> > +             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 +338,7 @@ 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;
> >               }
> > @@ -601,7 +727,7 @@ 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;
> >
> >
>
>
diff mbox series

Patch

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index eeb0b52203e9..0ee2924991fb 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -1581,10 +1581,10 @@  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);
+extern int alloc_shrinker_maps(struct mem_cgroup *memcg);
+extern void free_shrinker_maps(struct mem_cgroup *memcg);
+extern 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 +1594,8 @@  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 e2de77b5bcc2..f5c9a0d2160b 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -397,130 +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);
-		if (map)
-			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
@@ -5370,11 +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;
 	}
@@ -5438,7 +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..d950cead66ca 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -185,6 +185,132 @@  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);
+		if (map)
+			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 +338,7 @@  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;
 		}
@@ -601,7 +727,7 @@  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;