From: Roman Gushchin <guro@xxxxxx> Subject: 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. Link: http://lkml.kernel.org/r/20200623174037.3951353-16-guro@xxxxxx Signed-off-by: Roman Gushchin <guro@xxxxxx> Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx> Reviewed-by: Shakeel Butt <shakeelb@xxxxxxxxxx> Cc: Christoph Lameter <cl@xxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/slab.c | 1 - mm/slab.h | 17 ----------------- mm/slab_common.c | 37 ++++++++----------------------------- mm/slub.c | 1 - 4 files changed, 8 insertions(+), 48 deletions(-) --- a/mm/slab.c~mm-memcg-slab-deprecate-slab_root_caches +++ a/mm/slab.c @@ -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; /* --- a/mm/slab_common.c~mm-memcg-slab-deprecate-slab_root_caches +++ a/mm/slab_common.c @@ -131,9 +131,6 @@ int __kmem_cache_alloc_bulk(struct kmem_ } #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 kme 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(unsign 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(c 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_ca 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 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 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 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 se 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. */ --- a/mm/slab.h~mm-memcg-slab-deprecate-slab_root_caches +++ a/mm/slab.h @@ -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_flag } #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( } 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_param { } -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) --- a/mm/slub.c~mm-memcg-slab-deprecate-slab_root_caches +++ a/mm/slub.c @@ -4360,7 +4360,6 @@ static struct kmem_cache * __init bootst } slab_init_memcg_params(s); list_add(&s->list, &slab_caches); - memcg_link_cache(s); return s; } _
