From 10befea91b61c4e2c2d1df06a2e978d182fcf792 Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Thu, 6 Aug 2020 23:21:27 -0700 Subject: mm: memcg/slab: use a single set of kmem_caches for all allocations Instead of having two sets of kmem_caches: one for system-wide and non-accounted allocations and the second one shared by all accounted allocations, we can use just one. The idea is simple: space for obj_cgroup metadata can be allocated on demand and filled only for accounted allocations. It allows to remove a bunch of code which is required to handle kmem_cache clones for accounted allocations. There is no more need to create them, accumulate statistics, propagate attributes, etc. It's a quite significant simplification. Also, because the total number of slab_caches is reduced almost twice (not all kmem_caches have a memcg clone), some additional memory savings are expected. On my devvm it additionally saves about 3.5% of slab memory. [guro@fb.com: fix build on MIPS] Link: http://lkml.kernel.org/r/20200717214810.3733082-1-guro@fb.com Suggested-by: Johannes Weiner Signed-off-by: Roman Gushchin Signed-off-by: Andrew Morton Reviewed-by: Vlastimil Babka Reviewed-by: Shakeel Butt Cc: Christoph Lameter Cc: Michal Hocko Cc: Tejun Heo Cc: Naresh Kamboju Link: http://lkml.kernel.org/r/20200623174037.3951353-18-guro@fb.com Signed-off-by: Linus Torvalds --- mm/slub.c | 163 ++------------------------------------------------------------ 1 file changed, 4 insertions(+), 159 deletions(-) (limited to 'mm/slub.c') diff --git a/mm/slub.c b/mm/slub.c index 9cd724fe37d8..eba8f57d5734 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -218,14 +218,10 @@ enum track_item { TRACK_ALLOC, TRACK_FREE }; #ifdef CONFIG_SYSFS static int sysfs_slab_add(struct kmem_cache *); static int sysfs_slab_alias(struct kmem_cache *, const char *); -static void memcg_propagate_slab_attrs(struct kmem_cache *s); -static void sysfs_slab_remove(struct kmem_cache *s); #else static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; } static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p) { return 0; } -static inline void memcg_propagate_slab_attrs(struct kmem_cache *s) { } -static inline void sysfs_slab_remove(struct kmem_cache *s) { } #endif static inline void stat(const struct kmem_cache *s, enum stat_item si) @@ -1624,10 +1620,8 @@ static inline struct page *alloc_slab_page(struct kmem_cache *s, else page = __alloc_pages_node(node, flags, order); - if (page && charge_slab_page(page, flags, order, s)) { - __free_pages(page, order); - page = NULL; - } + if (page) + charge_slab_page(page, flags, order, s); return page; } @@ -3920,7 +3914,6 @@ int __kmem_cache_shutdown(struct kmem_cache *s) if (n->nr_partial || slabs_node(s, node)) return 1; } - sysfs_slab_remove(s); return 0; } @@ -4358,7 +4351,6 @@ static struct kmem_cache * __init bootstrap(struct kmem_cache *static_cache) p->slab_cache = s; #endif } - slab_init_memcg_params(s); list_add(&s->list, &slab_caches); return s; } @@ -4414,7 +4406,7 @@ struct kmem_cache * __kmem_cache_alias(const char *name, unsigned int size, unsigned int align, slab_flags_t flags, void (*ctor)(void *)) { - struct kmem_cache *s, *c; + struct kmem_cache *s; s = find_mergeable(size, align, flags, name, ctor); if (s) { @@ -4427,12 +4419,6 @@ __kmem_cache_alias(const char *name, unsigned int size, unsigned int align, s->object_size = max(s->object_size, size); s->inuse = max(s->inuse, ALIGN(size, sizeof(void *))); - c = memcg_cache(s); - if (c) { - c->object_size = s->object_size; - c->inuse = max(c->inuse, ALIGN(size, sizeof(void *))); - } - if (sysfs_slab_alias(s, name)) { s->refcount--; s = NULL; @@ -4454,7 +4440,6 @@ int __kmem_cache_create(struct kmem_cache *s, slab_flags_t flags) if (slab_state <= UP) return 0; - memcg_propagate_slab_attrs(s); err = sysfs_slab_add(s); if (err) __kmem_cache_release(s); @@ -5312,7 +5297,7 @@ static ssize_t shrink_store(struct kmem_cache *s, const char *buf, size_t length) { if (buf[0] == '1') - kmem_cache_shrink_all(s); + kmem_cache_shrink(s); else return -EINVAL; return length; @@ -5536,99 +5521,9 @@ static ssize_t slab_attr_store(struct kobject *kobj, return -EIO; err = attribute->store(s, buf, len); -#ifdef CONFIG_MEMCG - if (slab_state >= FULL && err >= 0 && is_root_cache(s)) { - struct kmem_cache *c; - - mutex_lock(&slab_mutex); - if (s->max_attr_size < len) - s->max_attr_size = len; - - /* - * This is a best effort propagation, so this function's return - * value will be determined by the parent cache only. This is - * basically because not all attributes will have a well - * defined semantics for rollbacks - most of the actions will - * have permanent effects. - * - * Returning the error value of any of the children that fail - * is not 100 % defined, in the sense that users seeing the - * error code won't be able to know anything about the state of - * the cache. - * - * Only returning the error code for the parent cache at least - * has well defined semantics. The cache being written to - * directly either failed or succeeded, in which case we loop - * through the descendants with best-effort propagation. - */ - c = memcg_cache(s); - if (c) - attribute->store(c, buf, len); - mutex_unlock(&slab_mutex); - } -#endif return err; } -static void memcg_propagate_slab_attrs(struct kmem_cache *s) -{ -#ifdef CONFIG_MEMCG - int i; - char *buffer = NULL; - struct kmem_cache *root_cache; - - if (is_root_cache(s)) - return; - - root_cache = s->memcg_params.root_cache; - - /* - * This mean this cache had no attribute written. Therefore, no point - * in copying default values around - */ - if (!root_cache->max_attr_size) - return; - - for (i = 0; i < ARRAY_SIZE(slab_attrs); i++) { - char mbuf[64]; - char *buf; - struct slab_attribute *attr = to_slab_attr(slab_attrs[i]); - ssize_t len; - - if (!attr || !attr->store || !attr->show) - continue; - - /* - * It is really bad that we have to allocate here, so we will - * do it only as a fallback. If we actually allocate, though, - * we can just use the allocated buffer until the end. - * - * Most of the slub attributes will tend to be very small in - * size, but sysfs allows buffers up to a page, so they can - * theoretically happen. - */ - if (buffer) - buf = buffer; - else if (root_cache->max_attr_size < ARRAY_SIZE(mbuf) && - !IS_ENABLED(CONFIG_SLUB_STATS)) - buf = mbuf; - else { - buffer = (char *) get_zeroed_page(GFP_KERNEL); - if (WARN_ON(!buffer)) - continue; - buf = buffer; - } - - len = attr->show(root_cache, buf); - if (len > 0) - attr->store(s, buf, len); - } - - if (buffer) - free_page((unsigned long)buffer); -#endif /* CONFIG_MEMCG */ -} - static void kmem_cache_release(struct kobject *k) { slab_kmem_cache_release(to_slab(k)); @@ -5648,10 +5543,6 @@ static struct kset *slab_kset; static inline struct kset *cache_kset(struct kmem_cache *s) { -#ifdef CONFIG_MEMCG - if (!is_root_cache(s)) - return s->memcg_params.root_cache->memcg_kset; -#endif return slab_kset; } @@ -5694,27 +5585,6 @@ static char *create_unique_id(struct kmem_cache *s) return name; } -static void sysfs_slab_remove_workfn(struct work_struct *work) -{ - struct kmem_cache *s = - container_of(work, struct kmem_cache, kobj_remove_work); - - if (!s->kobj.state_in_sysfs) - /* - * For a memcg cache, this may be called during - * deactivation and again on shutdown. Remove only once. - * A cache is never shut down before deactivation is - * complete, so no need to worry about synchronization. - */ - goto out; - -#ifdef CONFIG_MEMCG - kset_unregister(s->memcg_kset); -#endif -out: - kobject_put(&s->kobj); -} - static int sysfs_slab_add(struct kmem_cache *s) { int err; @@ -5722,8 +5592,6 @@ static int sysfs_slab_add(struct kmem_cache *s) struct kset *kset = cache_kset(s); int unmergeable = slab_unmergeable(s); - INIT_WORK(&s->kobj_remove_work, sysfs_slab_remove_workfn); - if (!kset) { kobject_init(&s->kobj, &slab_ktype); return 0; @@ -5760,16 +5628,6 @@ static int sysfs_slab_add(struct kmem_cache *s) if (err) goto out_del_kobj; -#ifdef CONFIG_MEMCG - if (is_root_cache(s) && memcg_sysfs_enabled) { - s->memcg_kset = kset_create_and_add("cgroup", NULL, &s->kobj); - if (!s->memcg_kset) { - err = -ENOMEM; - goto out_del_kobj; - } - } -#endif - if (!unmergeable) { /* Setup first alias */ sysfs_slab_alias(s, s->name); @@ -5783,19 +5641,6 @@ out_del_kobj: goto out; } -static void sysfs_slab_remove(struct kmem_cache *s) -{ - if (slab_state < FULL) - /* - * Sysfs has not been setup yet so no need to remove the - * cache from sysfs. - */ - return; - - kobject_get(&s->kobj); - schedule_work(&s->kobj_remove_work); -} - void sysfs_slab_unlink(struct kmem_cache *s) { if (slab_state >= FULL) -- cgit v1.2.3