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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: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Shakeel 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: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Roman Gushchin 2020-08-06 23:21:20 -07:00 committed by Linus Torvalds
parent 272911a4ad
commit c7094406fc
4 changed files with 8 additions and 48 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
mm/slab.c
View File

@ -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;
/*

17
mm/slab.h
View File

@ -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)

37
mm/slab_common.c
View File

@ -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)
@ -1165,11 +1143,12 @@ 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);
cache_show(s, 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.
*/

1
mm/slub.c
View File

@ -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;
}