Commit c7094406 authored by Roman Gushchin's avatar Roman Gushchin Committed by Linus Torvalds
Browse files

mm: memcg/slab: deprecate slab_root_caches 



Currently there are two lists of kmem_caches:
1) slab_caches, which contains all kmem_caches,
2) slab_root_caches, which contains only root kmem_caches.

And there is some preprocessor magic to have a single list if
CONFIG_MEMCG_KMEM isn't enabled.

It was required earlier because the number of non-root kmem_caches was
proportional to the number of memory cgroups and could reach really big
values.  Now, when it cannot exceed the number of root kmem_caches, there
is really no reason to maintain two lists.

We never iterate over the slab_root_caches list on any hot paths, so it's
perfectly fine to iterate over slab_caches and filter out non-root
kmem_caches.

It allows to remove a lot of config-dependent code and two pointers from
the kmem_cache structure.

Signed-off-by: default avatarRoman Gushchin <guro@fb.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Reviewed-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reviewed-by: default avatarShakeel Butt <shakeelb@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Tejun Heo <tj@kernel.org>
Link: http://lkml.kernel.org/r/20200623174037.3951353-16-guro@fb.com


Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 272911a4

mm/slab.c

+0 −1
Original line number Diff line number Diff line
@@ -1249,7 +1249,6 @@ void __init kmem_cache_init(void) 
				  nr_node_ids * sizeof(struct kmem_cache_node *),

				  SLAB_HWCACHE_ALIGN, 0, 0);

	list_add(&kmem_cache->list, &slab_caches);

	memcg_link_cache(kmem_cache);

	slab_state = PARTIAL;



	/*

mm/slab.h

+0 −17
Original line number Diff line number Diff line
@@ -44,14 +44,12 @@ struct kmem_cache { 
 *

 * @memcg_cache: pointer to memcg kmem cache, used by all non-root memory

 *		cgroups.

 * @root_caches_node: list node for slab_root_caches list.

 * @work: work struct used to create the non-root cache.

 */

struct memcg_cache_params {

	struct kmem_cache *root_cache;



	struct kmem_cache *memcg_cache;

	struct list_head __root_caches_node;

	struct work_struct work;

};

#endif /* CONFIG_SLOB */
@@ -265,11 +263,6 @@ static inline bool kmem_cache_debug_flags(struct kmem_cache *s, slab_flags_t fla 
}



#ifdef CONFIG_MEMCG_KMEM



/* List of all root caches. */

extern struct list_head		slab_root_caches;

#define root_caches_node	memcg_params.__root_caches_node



static inline bool is_root_cache(struct kmem_cache *s)

{

	return !s->memcg_params.root_cache;
@@ -447,14 +440,8 @@ static inline void memcg_slab_free_hook(struct kmem_cache *s, struct page *page, 
}



extern void slab_init_memcg_params(struct kmem_cache *);

extern void memcg_link_cache(struct kmem_cache *s);



#else /* CONFIG_MEMCG_KMEM */



/* If !memcg, all caches are root. */

#define slab_root_caches	slab_caches

#define root_caches_node	list



static inline bool is_root_cache(struct kmem_cache *s)

{

	return true;
@@ -523,10 +510,6 @@ static inline void slab_init_memcg_params(struct kmem_cache *s) 
{

}



static inline void memcg_link_cache(struct kmem_cache *s)

{

}



#endif /* CONFIG_MEMCG_KMEM */



static inline struct kmem_cache *virt_to_cache(const void *obj)

mm/slab_common.c

+8 −29
Original line number Diff line number Diff line
@@ -131,9 +131,6 @@ int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr, 
}



#ifdef CONFIG_MEMCG_KMEM



LIST_HEAD(slab_root_caches);



static void memcg_kmem_cache_create_func(struct work_struct *work)

{

	struct kmem_cache *cachep = container_of(work, struct kmem_cache,
@@ -156,27 +153,11 @@ static void init_memcg_params(struct kmem_cache *s, 
	else

		slab_init_memcg_params(s);

}



void memcg_link_cache(struct kmem_cache *s)

{

	if (is_root_cache(s))

		list_add(&s->root_caches_node, &slab_root_caches);

}



static void memcg_unlink_cache(struct kmem_cache *s)

{

	if (is_root_cache(s))

		list_del(&s->root_caches_node);

}

#else

static inline void init_memcg_params(struct kmem_cache *s,

				     struct kmem_cache *root_cache)

{

}



static inline void memcg_unlink_cache(struct kmem_cache *s)

{

}

#endif /* CONFIG_MEMCG_KMEM */



/*
@@ -253,7 +234,7 @@ struct kmem_cache *find_mergeable(unsigned int size, unsigned int align, 
	if (flags & SLAB_NEVER_MERGE)

		return NULL;



	list_for_each_entry_reverse(s, &slab_root_caches, root_caches_node) {

	list_for_each_entry_reverse(s, &slab_caches, list) {

		if (slab_unmergeable(s))

			continue;
@@ -312,7 +293,6 @@ static struct kmem_cache *create_cache(const char *name, 


	s->refcount = 1;

	list_add(&s->list, &slab_caches);

	memcg_link_cache(s);

out:

	if (err)

		return ERR_PTR(err);
@@ -507,7 +487,6 @@ static int shutdown_cache(struct kmem_cache *s) 
	if (__kmem_cache_shutdown(s) != 0)

		return -EBUSY;



	memcg_unlink_cache(s);

	list_del(&s->list);



	if (s->flags & SLAB_TYPESAFE_BY_RCU) {
@@ -751,7 +730,6 @@ struct kmem_cache *__init create_kmalloc_cache(const char *name, 


	create_boot_cache(s, name, size, flags, useroffset, usersize);

	list_add(&s->list, &slab_caches);

	memcg_link_cache(s);

	s->refcount = 1;

	return s;

}
@@ -1107,12 +1085,12 @@ static void print_slabinfo_header(struct seq_file *m) 
void *slab_start(struct seq_file *m, loff_t *pos)

{

	mutex_lock(&slab_mutex);

	return seq_list_start(&slab_root_caches, *pos);

	return seq_list_start(&slab_caches, *pos);

}



void *slab_next(struct seq_file *m, void *p, loff_t *pos)

{

	return seq_list_next(p, &slab_root_caches, pos);

	return seq_list_next(p, &slab_caches, pos);

}



void slab_stop(struct seq_file *m, void *p)
@@ -1165,10 +1143,11 @@ static void cache_show(struct kmem_cache *s, struct seq_file *m) 


static int slab_show(struct seq_file *m, void *p)

{

	struct kmem_cache *s = list_entry(p, struct kmem_cache, root_caches_node);

	struct kmem_cache *s = list_entry(p, struct kmem_cache, list);



	if (p == slab_root_caches.next)

	if (p == slab_caches.next)

		print_slabinfo_header(m);

	if (is_root_cache(s))

		cache_show(s, m);

	return 0;

}
@@ -1271,7 +1250,7 @@ static int memcg_slabinfo_show(struct seq_file *m, void *unused) 
	mutex_lock(&slab_mutex);

	seq_puts(m, "# <name> <css_id[:dead|deact]> <active_objs> <num_objs>");

	seq_puts(m, " <active_slabs> <num_slabs>\n");

	list_for_each_entry(s, &slab_root_caches, root_caches_node) {

	list_for_each_entry(s, &slab_caches, list) {

		/*

		 * Skip kmem caches that don't have the memcg cache.

		 */

mm/slub.c

+0 −1
Original line number Diff line number Diff line
@@ -4360,7 +4360,6 @@ static struct kmem_cache * __init bootstrap(struct kmem_cache *static_cache) 
	}

	slab_init_memcg_params(s);

	list_add(&s->list, &slab_caches);

	memcg_link_cache(s);

	return s;

}

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