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Howlett" , Christoph Lameter , David Rientjes Cc: Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Uladzislau Rezki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, maple-tree@lists.infradead.org, Vlastimil Babka X-Mailer: b4 0.14.2 X-Spam-Level: X-Spamd-Result: default: False [-4.00 / 50.00]; REPLY(-4.00)[]; TAGGED_RCPT(0.00)[] X-Spam-Score: -4.00 X-Spam-Flag: NO X-Rspamd-Queue-Id: 7C7961F381 X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Action: no action X-Rspamd-Server: rspamd2.dmz-prg2.suse.org Specifying a non-zero value for a new struct kmem_cache_args field sheaf_capacity will setup a caching layer of percpu arrays called sheaves of given capacity for the created cache. Allocations from the cache will allocate via the percpu sheaves (main or spare) as long as they have no NUMA node preference. Frees will also refill one of the sheaves. When both percpu sheaves are found empty during an allocation, an empty sheaf may be replaced with a full one from the per-node barn. If none are available and the allocation is allowed to block, an empty sheaf is refilled from slab(s) by an internal bulk alloc operation. When both percpu sheaves are full during freeing, the barn can replace a full one with an empty one, unless over a full sheaves limit. In that case a sheaf is flushed to slab(s) by an internal bulk free operation. Flushing sheaves and barns is also wired to the existing cpu flushing and cache shrinking operations. The sheaves do not distinguish NUMA locality of the cached objects. If an allocation is requested with kmem_cache_alloc_node() with a specific node (not NUMA_NO_NODE), sheaves are bypassed. The bulk operations exposed to slab users also try to utilize the sheaves as long as the necessary (full or empty) sheaves are available on the cpu or in the barn. Once depleted, they will fallback to bulk alloc/free to slabs directly to avoid double copying. Sysfs stat counters alloc_cpu_sheaf and free_cpu_sheaf count objects allocated or freed using the sheaves. Counters sheaf_refill, sheaf_flush_main and sheaf_flush_other count objects filled or flushed from or to slab pages, and can be used to assess how effective the caching is. The refill and flush operations will also count towards the usual alloc_fastpath/slowpath, free_fastpath/slowpath and other counters. Access to the percpu sheaves is protected by local_lock_irqsave() operations, each per-NUMA-node barn has a spin_lock. A current limitation is that when slub_debug is enabled for a cache with percpu sheaves, the objects in the array are considered as allocated from the slub_debug perspective, and the alloc/free debugging hooks occur when moving the objects between the array and slab pages. This means that e.g. an use-after-free that occurs for an object cached in the array is undetected. Collected alloc/free stacktraces might also be less useful. This limitation could be changed in the future. On the other hand, KASAN, kmemcg and other hooks are executed on actual allocations and frees by kmem_cache users even if those use the array, so their debugging or accounting accuracy should be unaffected. Signed-off-by: Vlastimil Babka --- include/linux/slab.h | 34 ++ mm/slab.h | 2 + mm/slab_common.c | 5 +- mm/slub.c | 982 ++++++++++++++++++++++++++++++++++++++++++++++++--- 4 files changed, 973 insertions(+), 50 deletions(-) diff --git a/include/linux/slab.h b/include/linux/slab.h index 7686054dd494cc65def7f58748718e03eb78e481..0e1b25228c77140d05b5b4433c9d7923de36ec05 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -332,6 +332,40 @@ struct kmem_cache_args { * %NULL means no constructor. */ void (*ctor)(void *); + /** + * @sheaf_capacity: Enable sheaves of given capacity for the cache. + * + * With a non-zero value, allocations from the cache go through caching + * arrays called sheaves. Each cpu has a main sheaf that's always + * present, and a spare sheaf thay may be not present. When both become + * empty, there's an attempt to replace an empty sheaf with a full sheaf + * from the per-node barn. + * + * When no full sheaf is available, and gfp flags allow blocking, a + * sheaf is allocated and filled from slab(s) using bulk allocation. + * Otherwise the allocation falls back to the normal operation + * allocating a single object from a slab. + * + * Analogically when freeing and both percpu sheaves are full, the barn + * may replace it with an empty sheaf, unless it's over capacity. In + * that case a sheaf is bulk freed to slab pages. + * + * The sheaves does not distinguish NUMA placement of objects, so + * allocations via kmem_cache_alloc_node() with a node specified other + * than NUMA_NO_NODE will bypass them. + * + * Bulk allocation and free operations also try to use the cpu sheaves + * and barn, but fallback to using slab pages directly. + * + * Limitations: when slub_debug is enabled for the cache, all relevant + * actions (i.e. poisoning, obtaining stacktraces) and checks happen + * when objects move between sheaves and slab pages, which may result in + * e.g. not detecting a use-after-free while the object is in the array + * cache, and the stacktraces may be less useful. + * + * %0 means no sheaves will be created + */ + unsigned int sheaf_capacity; }; struct kmem_cache *__kmem_cache_create_args(const char *name, diff --git a/mm/slab.h b/mm/slab.h index 2f01c7317988ce036f0b22807403226a59f0f708..8daaec53b6ecfc44171191d421adb12e5cba2c58 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -259,6 +259,7 @@ struct kmem_cache { #ifndef CONFIG_SLUB_TINY struct kmem_cache_cpu __percpu *cpu_slab; #endif + struct slub_percpu_sheaves __percpu *cpu_sheaves; /* Used for retrieving partial slabs, etc. */ slab_flags_t flags; unsigned long min_partial; @@ -272,6 +273,7 @@ struct kmem_cache { /* Number of per cpu partial slabs to keep around */ unsigned int cpu_partial_slabs; #endif + unsigned int sheaf_capacity; struct kmem_cache_order_objects oo; /* Allocation and freeing of slabs */ diff --git a/mm/slab_common.c b/mm/slab_common.c index 46d0a4cd33b5982fd79c307d572f231fdea9514a..ceeefb287899a82f30ad79b403556001c1860311 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -163,6 +163,9 @@ int slab_unmergeable(struct kmem_cache *s) return 1; #endif + if (s->cpu_sheaves) + return 1; + /* * We may have set a slab to be unmergeable during bootstrap. */ @@ -328,7 +331,7 @@ struct kmem_cache *__kmem_cache_create_args(const char *name, object_size - args->usersize < args->useroffset)) args->usersize = args->useroffset = 0; - if (!args->usersize) + if (!args->usersize && !args->sheaf_capacity) s = __kmem_cache_alias(name, object_size, args->align, flags, args->ctor); if (s) diff --git a/mm/slub.c b/mm/slub.c index e8273f28656936c05d015c53923f8fe69cd161b2..c06734912972b799f537359f7fe6a750918ffe9e 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -346,8 +346,10 @@ static inline void debugfs_slab_add(struct kmem_cache *s) { } #endif enum stat_item { + ALLOC_PCS, /* Allocation from percpu sheaf */ ALLOC_FASTPATH, /* Allocation from cpu slab */ ALLOC_SLOWPATH, /* Allocation by getting a new cpu slab */ + FREE_PCS, /* Free to percpu sheaf */ FREE_FASTPATH, /* Free to cpu slab */ FREE_SLOWPATH, /* Freeing not to cpu slab */ FREE_FROZEN, /* Freeing to frozen slab */ @@ -372,6 +374,12 @@ enum stat_item { CPU_PARTIAL_FREE, /* Refill cpu partial on free */ CPU_PARTIAL_NODE, /* Refill cpu partial from node partial */ CPU_PARTIAL_DRAIN, /* Drain cpu partial to node partial */ + SHEAF_FLUSH_MAIN, /* Objects flushed from main percpu sheaf */ + SHEAF_FLUSH_OTHER, /* Objects flushed from other sheaves */ + SHEAF_REFILL, /* Objects refilled to a sheaf */ + SHEAF_SWAP, /* Swapping main and spare sheaf */ + SHEAF_ALLOC, /* Allocation of an empty sheaf */ + SHEAF_FREE, /* Freeing of an empty sheaf */ NR_SLUB_STAT_ITEMS }; @@ -418,6 +426,35 @@ void stat_add(const struct kmem_cache *s, enum stat_item si, int v) #endif } +#define MAX_FULL_SHEAVES 10 +#define MAX_EMPTY_SHEAVES 10 + +struct node_barn { + spinlock_t lock; + struct list_head sheaves_full; + struct list_head sheaves_empty; + unsigned int nr_full; + unsigned int nr_empty; +}; + +struct slab_sheaf { + union { + struct rcu_head rcu_head; + struct list_head barn_list; + }; + struct kmem_cache *cache; + unsigned int size; + void *objects[]; +}; + +struct slub_percpu_sheaves { + local_lock_t lock; + struct slab_sheaf *main; /* never NULL when unlocked */ + struct slab_sheaf *spare; /* empty or full, may be NULL */ + struct slab_sheaf *rcu_free; + struct node_barn *barn; +}; + /* * The slab lists for all objects. */ @@ -430,6 +467,7 @@ struct kmem_cache_node { atomic_long_t total_objects; struct list_head full; #endif + struct node_barn *barn; }; static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node) @@ -453,12 +491,19 @@ static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node) */ static nodemask_t slab_nodes; -#ifndef CONFIG_SLUB_TINY /* * Workqueue used for flush_cpu_slab(). */ static struct workqueue_struct *flushwq; -#endif + +struct slub_flush_work { + struct work_struct work; + struct kmem_cache *s; + bool skip; +}; + +static DEFINE_MUTEX(flush_lock); +static DEFINE_PER_CPU(struct slub_flush_work, slub_flush); /******************************************************************** * Core slab cache functions @@ -2410,6 +2455,349 @@ static void *setup_object(struct kmem_cache *s, void *object) return object; } +static struct slab_sheaf *alloc_empty_sheaf(struct kmem_cache *s, gfp_t gfp) +{ + struct slab_sheaf *sheaf = kzalloc(struct_size(sheaf, objects, + s->sheaf_capacity), gfp); + + if (unlikely(!sheaf)) + return NULL; + + sheaf->cache = s; + + stat(s, SHEAF_ALLOC); + + return sheaf; +} + +static void free_empty_sheaf(struct kmem_cache *s, struct slab_sheaf *sheaf) +{ + kfree(sheaf); + + stat(s, SHEAF_FREE); +} + +static int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, + size_t size, void **p); + + +static int refill_sheaf(struct kmem_cache *s, struct slab_sheaf *sheaf, + gfp_t gfp) +{ + int to_fill = s->sheaf_capacity - sheaf->size; + int filled; + + if (!to_fill) + return 0; + + filled = __kmem_cache_alloc_bulk(s, gfp, to_fill, + &sheaf->objects[sheaf->size]); + + if (!filled) + return -ENOMEM; + + sheaf->size = s->sheaf_capacity; + + stat_add(s, SHEAF_REFILL, filled); + + return 0; +} + + +static struct slab_sheaf *alloc_full_sheaf(struct kmem_cache *s, gfp_t gfp) +{ + struct slab_sheaf *sheaf = alloc_empty_sheaf(s, gfp); + + if (!sheaf) + return NULL; + + if (refill_sheaf(s, sheaf, gfp)) { + free_empty_sheaf(s, sheaf); + return NULL; + } + + return sheaf; +} + +/* + * Maximum number of objects freed during a single flush of main pcs sheaf. + * Translates directly to an on-stack array size. + */ +#define PCS_BATCH_MAX 32U + +static void __kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p); + +static void sheaf_flush_main(struct kmem_cache *s) +{ + struct slub_percpu_sheaves *pcs; + unsigned int batch, remaining; + void *objects[PCS_BATCH_MAX]; + struct slab_sheaf *sheaf; + unsigned long flags; + +next_batch: + local_lock_irqsave(&s->cpu_sheaves->lock, flags); + pcs = this_cpu_ptr(s->cpu_sheaves); + sheaf = pcs->main; + + batch = min(PCS_BATCH_MAX, sheaf->size); + + sheaf->size -= batch; + memcpy(objects, sheaf->objects + sheaf->size, batch * sizeof(void *)); + + remaining = sheaf->size; + + local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + + __kmem_cache_free_bulk(s, batch, &objects[0]); + + stat_add(s, SHEAF_FLUSH_MAIN, batch); + + if (remaining) + goto next_batch; +} + +static void sheaf_flush(struct kmem_cache *s, struct slab_sheaf *sheaf) +{ + if (!sheaf->size) + return; + + stat_add(s, SHEAF_FLUSH_OTHER, sheaf->size); + + __kmem_cache_free_bulk(s, sheaf->size, &sheaf->objects[0]); + + sheaf->size = 0; +} + +/* + * Caller needs to make sure migration is disabled in order to fully flush + * single cpu's sheaves + * + * flushing operations are rare so let's keep it simple and flush to slabs + * directly, skipping the barn + */ +static void pcs_flush_all(struct kmem_cache *s) +{ + struct slub_percpu_sheaves *pcs; + struct slab_sheaf *spare, *rcu_free; + unsigned long flags; + + local_lock_irqsave(&s->cpu_sheaves->lock, flags); + pcs = this_cpu_ptr(s->cpu_sheaves); + + spare = pcs->spare; + pcs->spare = NULL; + + rcu_free = pcs->rcu_free; + pcs->rcu_free = NULL; + + local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + + if (spare) { + sheaf_flush(s, spare); + free_empty_sheaf(s, spare); + } + + // TODO: handle rcu_free + BUG_ON(rcu_free); + + sheaf_flush_main(s); +} + +static void __pcs_flush_all_cpu(struct kmem_cache *s, unsigned int cpu) +{ + struct slub_percpu_sheaves *pcs; + + pcs = per_cpu_ptr(s->cpu_sheaves, cpu); + + if (pcs->spare) { + sheaf_flush(s, pcs->spare); + free_empty_sheaf(s, pcs->spare); + pcs->spare = NULL; + } + + // TODO: handle rcu_free + BUG_ON(pcs->rcu_free); + + sheaf_flush_main(s); +} + +static void pcs_destroy(struct kmem_cache *s) +{ + int cpu; + + for_each_possible_cpu(cpu) { + struct slub_percpu_sheaves *pcs; + + pcs = per_cpu_ptr(s->cpu_sheaves, cpu); + + /* can happen when unwinding failed create */ + if (!pcs->main) + continue; + + WARN_ON(pcs->spare); + WARN_ON(pcs->rcu_free); + + if (!WARN_ON(pcs->main->size)) { + free_empty_sheaf(s, pcs->main); + pcs->main = NULL; + } + } + + free_percpu(s->cpu_sheaves); + s->cpu_sheaves = NULL; +} + +static struct slab_sheaf *barn_get_empty_sheaf(struct node_barn *barn) +{ + struct slab_sheaf *empty = NULL; + unsigned long flags; + + spin_lock_irqsave(&barn->lock, flags); + + if (barn->nr_empty) { + empty = list_first_entry(&barn->sheaves_empty, + struct slab_sheaf, barn_list); + list_del(&empty->barn_list); + barn->nr_empty--; + } + + spin_unlock_irqrestore(&barn->lock, flags); + + return empty; +} + +static int barn_put_empty_sheaf(struct node_barn *barn, + struct slab_sheaf *sheaf, bool ignore_limit) +{ + unsigned long flags; + int ret = 0; + + spin_lock_irqsave(&barn->lock, flags); + + if (!ignore_limit && barn->nr_empty >= MAX_EMPTY_SHEAVES) { + ret = -E2BIG; + } else { + list_add(&sheaf->barn_list, &barn->sheaves_empty); + barn->nr_empty++; + } + + spin_unlock_irqrestore(&barn->lock, flags); + return ret; +} + +static int barn_put_full_sheaf(struct node_barn *barn, struct slab_sheaf *sheaf, + bool ignore_limit) +{ + unsigned long flags; + int ret = 0; + + spin_lock_irqsave(&barn->lock, flags); + + if (!ignore_limit && barn->nr_full >= MAX_FULL_SHEAVES) { + ret = -E2BIG; + } else { + list_add(&sheaf->barn_list, &barn->sheaves_full); + barn->nr_full++; + } + + spin_unlock_irqrestore(&barn->lock, flags); + return ret; +} + +/* + * If a full sheaf is available, return it and put the supplied empty one to + * barn. We ignore the limit on empty sheaves as the number of sheaves doesn't + * change. + */ +static struct slab_sheaf * +barn_replace_empty_sheaf(struct node_barn *barn, struct slab_sheaf *empty) +{ + struct slab_sheaf *full = NULL; + unsigned long flags; + + spin_lock_irqsave(&barn->lock, flags); + + if (barn->nr_full) { + full = list_first_entry(&barn->sheaves_full, struct slab_sheaf, + barn_list); + list_del(&full->barn_list); + list_add(&empty->barn_list, &barn->sheaves_empty); + barn->nr_full--; + barn->nr_empty++; + } + + spin_unlock_irqrestore(&barn->lock, flags); + + return full; +} +/* + * If a empty sheaf is available, return it and put the supplied full one to + * barn. But if there are too many full sheaves, reject this with -E2BIG. + */ +static struct slab_sheaf * +barn_replace_full_sheaf(struct node_barn *barn, struct slab_sheaf *full) +{ + struct slab_sheaf *empty; + unsigned long flags; + + spin_lock_irqsave(&barn->lock, flags); + + if (barn->nr_full >= MAX_FULL_SHEAVES) { + empty = ERR_PTR(-E2BIG); + } else if (!barn->nr_empty) { + empty = ERR_PTR(-ENOMEM); + } else { + empty = list_first_entry(&barn->sheaves_empty, struct slab_sheaf, + barn_list); + list_del(&empty->barn_list); + list_add(&full->barn_list, &barn->sheaves_full); + barn->nr_empty--; + barn->nr_full++; + } + + spin_unlock_irqrestore(&barn->lock, flags); + + return empty; +} + +static void barn_init(struct node_barn *barn) +{ + spin_lock_init(&barn->lock); + INIT_LIST_HEAD(&barn->sheaves_full); + INIT_LIST_HEAD(&barn->sheaves_empty); + barn->nr_full = 0; + barn->nr_empty = 0; +} + +static void barn_shrink(struct kmem_cache *s, struct node_barn *barn) +{ + struct list_head empty_list; + struct list_head full_list; + struct slab_sheaf *sheaf, *sheaf2; + unsigned long flags; + + INIT_LIST_HEAD(&empty_list); + INIT_LIST_HEAD(&full_list); + + spin_lock_irqsave(&barn->lock, flags); + + list_splice_init(&barn->sheaves_full, &full_list); + barn->nr_full = 0; + list_splice_init(&barn->sheaves_empty, &empty_list); + barn->nr_empty = 0; + + spin_unlock_irqrestore(&barn->lock, flags); + + list_for_each_entry_safe(sheaf, sheaf2, &full_list, barn_list) { + sheaf_flush(s, sheaf); + list_move(&sheaf->barn_list, &empty_list); + } + + list_for_each_entry_safe(sheaf, sheaf2, &empty_list, barn_list) + free_empty_sheaf(s, sheaf); +} + /* * Slab allocation and freeing */ @@ -3280,11 +3668,42 @@ static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) put_partials_cpu(s, c); } -struct slub_flush_work { - struct work_struct work; - struct kmem_cache *s; - bool skip; -}; +static inline void flush_this_cpu_slab(struct kmem_cache *s) +{ + struct kmem_cache_cpu *c = this_cpu_ptr(s->cpu_slab); + + if (c->slab) + flush_slab(s, c); + + put_partials(s); +} + +static bool has_cpu_slab(int cpu, struct kmem_cache *s) +{ + struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu); + + return c->slab || slub_percpu_partial(c); +} + +#else /* CONFIG_SLUB_TINY */ +static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) { } +static inline bool has_cpu_slab(int cpu, struct kmem_cache *s) { return false; } +static inline void flush_this_cpu_slab(struct kmem_cache *s) { } +#endif /* CONFIG_SLUB_TINY */ + +static bool has_pcs_used(int cpu, struct kmem_cache *s) +{ + struct slub_percpu_sheaves *pcs; + + if (!s->cpu_sheaves) + return false; + + pcs = per_cpu_ptr(s->cpu_sheaves, cpu); + + return (pcs->spare || pcs->rcu_free || pcs->main->size); +} + +static void pcs_flush_all(struct kmem_cache *s); /* * Flush cpu slab. @@ -3294,30 +3713,18 @@ struct slub_flush_work { static void flush_cpu_slab(struct work_struct *w) { struct kmem_cache *s; - struct kmem_cache_cpu *c; struct slub_flush_work *sfw; sfw = container_of(w, struct slub_flush_work, work); s = sfw->s; - c = this_cpu_ptr(s->cpu_slab); - if (c->slab) - flush_slab(s, c); - - put_partials(s); -} - -static bool has_cpu_slab(int cpu, struct kmem_cache *s) -{ - struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu); + if (s->cpu_sheaves) + pcs_flush_all(s); - return c->slab || slub_percpu_partial(c); + flush_this_cpu_slab(s); } -static DEFINE_MUTEX(flush_lock); -static DEFINE_PER_CPU(struct slub_flush_work, slub_flush); - static void flush_all_cpus_locked(struct kmem_cache *s) { struct slub_flush_work *sfw; @@ -3328,7 +3735,7 @@ static void flush_all_cpus_locked(struct kmem_cache *s) for_each_online_cpu(cpu) { sfw = &per_cpu(slub_flush, cpu); - if (!has_cpu_slab(cpu, s)) { + if (!has_cpu_slab(cpu, s) && !has_pcs_used(cpu, s)) { sfw->skip = true; continue; } @@ -3364,19 +3771,14 @@ static int slub_cpu_dead(unsigned int cpu) struct kmem_cache *s; mutex_lock(&slab_mutex); - list_for_each_entry(s, &slab_caches, list) + list_for_each_entry(s, &slab_caches, list) { __flush_cpu_slab(s, cpu); + __pcs_flush_all_cpu(s, cpu); + } mutex_unlock(&slab_mutex); return 0; } -#else /* CONFIG_SLUB_TINY */ -static inline void flush_all_cpus_locked(struct kmem_cache *s) { } -static inline void flush_all(struct kmem_cache *s) { } -static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) { } -static inline int slub_cpu_dead(unsigned int cpu) { return 0; } -#endif /* CONFIG_SLUB_TINY */ - /* * Check if the objects in a per cpu structure fit numa * locality expectations. @@ -4126,6 +4528,173 @@ bool slab_post_alloc_hook(struct kmem_cache *s, struct list_lru *lru, return memcg_slab_post_alloc_hook(s, lru, flags, size, p); } +static __fastpath_inline +void *alloc_from_pcs(struct kmem_cache *s, gfp_t gfp) +{ + struct slub_percpu_sheaves *pcs; + unsigned long flags; + void *object; + + local_lock_irqsave(&s->cpu_sheaves->lock, flags); + pcs = this_cpu_ptr(s->cpu_sheaves); + + if (unlikely(pcs->main->size == 0)) { + + struct slab_sheaf *empty = NULL; + struct slab_sheaf *full; + bool can_alloc; + + if (pcs->spare && pcs->spare->size > 0) { + stat(s, SHEAF_SWAP); + swap(pcs->main, pcs->spare); + goto do_alloc; + } + + full = barn_replace_empty_sheaf(pcs->barn, pcs->main); + + if (full) { + pcs->main = full; + goto do_alloc; + } + + can_alloc = gfpflags_allow_blocking(gfp); + + if (can_alloc) { + if (pcs->spare) { + empty = pcs->spare; + pcs->spare = NULL; + } else { + empty = barn_get_empty_sheaf(pcs->barn); + } + } + + local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + + if (!can_alloc) + return NULL; + + if (empty) { + if (!refill_sheaf(s, empty, gfp)) { + full = empty; + } else { + /* + * we must be very low on memory so don't bother + * with the barn + */ + free_empty_sheaf(s, empty); + } + } else { + full = alloc_full_sheaf(s, gfp); + } + + if (!full) + return NULL; + + local_lock_irqsave(&s->cpu_sheaves->lock, flags); + pcs = this_cpu_ptr(s->cpu_sheaves); + + /* + * If we are returning empty sheaf, we either got it from the + * barn or had to allocate one. If we are returning a full + * sheaf, it's due to racing or being migrated to a different + * cpu. Breaching the barn's sheaf limits should be thus rare + * enough so just ignore them to simplify the recovery. + */ + + if (pcs->main->size == 0) { + barn_put_empty_sheaf(pcs->barn, pcs->main, true); + pcs->main = full; + goto do_alloc; + } + + if (!pcs->spare) { + pcs->spare = full; + goto do_alloc; + } + + if (pcs->spare->size == 0) { + barn_put_empty_sheaf(pcs->barn, pcs->spare, true); + pcs->spare = full; + goto do_alloc; + } + + barn_put_full_sheaf(pcs->barn, full, true); + } + +do_alloc: + object = pcs->main->objects[--pcs->main->size]; + + local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + + stat(s, ALLOC_PCS); + + return object; +} + +static __fastpath_inline +unsigned int alloc_from_pcs_bulk(struct kmem_cache *s, size_t size, void **p) +{ + struct slub_percpu_sheaves *pcs; + struct slab_sheaf *main; + unsigned long flags; + unsigned int allocated = 0; + unsigned int batch; + +next_batch: + local_lock_irqsave(&s->cpu_sheaves->lock, flags); + pcs = this_cpu_ptr(s->cpu_sheaves); + + if (unlikely(pcs->main->size == 0)) { + + struct slab_sheaf *full; + + if (pcs->spare && pcs->spare->size > 0) { + stat(s, SHEAF_SWAP); + swap(pcs->main, pcs->spare); + goto do_alloc; + } + + full = barn_replace_empty_sheaf(pcs->barn, pcs->main); + + if (full) { + pcs->main = full; + goto do_alloc; + } + + local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + + /* + * Once full sheaves in barn are depleted, let the bulk + * allocation continue from slab pages, otherwise we would just + * be copying arrays of pointers twice. + */ + return allocated; + } + +do_alloc: + + main = pcs->main; + batch = min(size, main->size); + + main->size -= batch; + memcpy(p, main->objects + main->size, batch * sizeof(void *)); + + local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + + stat_add(s, ALLOC_PCS, batch); + + allocated += batch; + + if (batch < size) { + p += batch; + size -= batch; + goto next_batch; + } + + return allocated; +} + + /* * Inlined fastpath so that allocation functions (kmalloc, kmem_cache_alloc) * have the fastpath folded into their functions. So no function call @@ -4150,7 +4719,11 @@ static __fastpath_inline void *slab_alloc_node(struct kmem_cache *s, struct list if (unlikely(object)) goto out; - object = __slab_alloc_node(s, gfpflags, node, addr, orig_size); + if (s->cpu_sheaves && (node == NUMA_NO_NODE)) + object = alloc_from_pcs(s, gfpflags); + + if (!object) + object = __slab_alloc_node(s, gfpflags, node, addr, orig_size); maybe_wipe_obj_freeptr(s, object); init = slab_want_init_on_alloc(gfpflags, s); @@ -4521,6 +5094,196 @@ static void __slab_free(struct kmem_cache *s, struct slab *slab, discard_slab(s, slab); } +/* + * Free an object to the percpu sheaves. + * The object is expected to have passed slab_free_hook() already. + */ +static __fastpath_inline +void free_to_pcs(struct kmem_cache *s, void *object) +{ + struct slub_percpu_sheaves *pcs; + unsigned long flags; + +restart: + local_lock_irqsave(&s->cpu_sheaves->lock, flags); + pcs = this_cpu_ptr(s->cpu_sheaves); + + if (unlikely(pcs->main->size == s->sheaf_capacity)) { + + struct slab_sheaf *empty; + + if (!pcs->spare) { + empty = barn_get_empty_sheaf(pcs->barn); + if (empty) { + pcs->spare = pcs->main; + pcs->main = empty; + goto do_free; + } + goto alloc_empty; + } + + if (pcs->spare->size < s->sheaf_capacity) { + stat(s, SHEAF_SWAP); + swap(pcs->main, pcs->spare); + goto do_free; + } + + empty = barn_replace_full_sheaf(pcs->barn, pcs->main); + + if (!IS_ERR(empty)) { + pcs->main = empty; + goto do_free; + } + + if (PTR_ERR(empty) == -E2BIG) { + /* Since we got here, spare exists and is full */ + struct slab_sheaf *to_flush = pcs->spare; + + pcs->spare = NULL; + local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + + sheaf_flush(s, to_flush); + empty = to_flush; + goto got_empty; + } + +alloc_empty: + local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + + empty = alloc_empty_sheaf(s, GFP_NOWAIT); + + if (!empty) { + sheaf_flush_main(s); + goto restart; + } + +got_empty: + local_lock_irqsave(&s->cpu_sheaves->lock, flags); + pcs = this_cpu_ptr(s->cpu_sheaves); + + /* + * if we put any sheaf to barn here, it's because we raced or + * have been migrated to a different cpu, which should be rare + * enough so just ignore the barn's limits to simplify + */ + if (unlikely(pcs->main->size < s->sheaf_capacity)) { + if (!pcs->spare) + pcs->spare = empty; + else + barn_put_empty_sheaf(pcs->barn, empty, true); + goto do_free; + } + + if (!pcs->spare) { + pcs->spare = pcs->main; + pcs->main = empty; + goto do_free; + } + + barn_put_full_sheaf(pcs->barn, pcs->main, true); + pcs->main = empty; + } + +do_free: + pcs->main->objects[pcs->main->size++] = object; + + local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + + stat(s, FREE_PCS); +} + +/* + * Bulk free objects to the percpu sheaves. + * Unlike free_to_pcs() this includes the calls to all necessary hooks + * and the fallback to freeing to slab pages. + */ +static void free_to_pcs_bulk(struct kmem_cache *s, size_t size, void **p) +{ + struct slub_percpu_sheaves *pcs; + struct slab_sheaf *main; + unsigned long flags; + unsigned int batch, i = 0; + bool init; + + init = slab_want_init_on_free(s); + + while (i < size) { + struct slab *slab = virt_to_slab(p[i]); + + memcg_slab_free_hook(s, slab, p + i, 1); + alloc_tagging_slab_free_hook(s, slab, p + i, 1); + + if (unlikely(!slab_free_hook(s, p[i], init, false))) { + p[i] = p[--size]; + if (!size) + return; + continue; + } + + i++; + } + +next_batch: + local_lock_irqsave(&s->cpu_sheaves->lock, flags); + pcs = this_cpu_ptr(s->cpu_sheaves); + + if (unlikely(pcs->main->size == s->sheaf_capacity)) { + + struct slab_sheaf *empty; + + if (!pcs->spare) { + empty = barn_get_empty_sheaf(pcs->barn); + if (empty) { + pcs->spare = pcs->main; + pcs->main = empty; + goto do_free; + } + goto no_empty; + } + + if (pcs->spare->size < s->sheaf_capacity) { + stat(s, SHEAF_SWAP); + swap(pcs->main, pcs->spare); + goto do_free; + } + + empty = barn_replace_full_sheaf(pcs->barn, pcs->main); + + if (!IS_ERR(empty)) { + pcs->main = empty; + goto do_free; + } + +no_empty: + local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + + /* + * if we depleted all empty sheaves in the barn or there are too + * many full sheaves, free the rest to slab pages + */ + + __kmem_cache_free_bulk(s, size, p); + return; + } + +do_free: + main = pcs->main; + batch = min(size, s->sheaf_capacity - main->size); + + memcpy(main->objects + main->size, p, batch * sizeof(void *)); + main->size += batch; + + local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + + stat_add(s, FREE_PCS, batch); + + if (batch < size) { + p += batch; + size -= batch; + goto next_batch; + } +} + #ifndef CONFIG_SLUB_TINY /* * Fastpath with forced inlining to produce a kfree and kmem_cache_free that @@ -4607,7 +5370,12 @@ void slab_free(struct kmem_cache *s, struct slab *slab, void *object, memcg_slab_free_hook(s, slab, &object, 1); alloc_tagging_slab_free_hook(s, slab, &object, 1); - if (likely(slab_free_hook(s, object, slab_want_init_on_free(s), false))) + if (unlikely(!slab_free_hook(s, object, slab_want_init_on_free(s), false))) + return; + + if (s->cpu_sheaves) + free_to_pcs(s, object); + else do_slab_free(s, slab, object, object, 1, addr); } @@ -5033,6 +5801,15 @@ void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p) if (!size) return; + /* + * freeing to sheaves is so incompatible with the detached freelist so + * once we go that way, we have to do everything differently + */ + if (s && s->cpu_sheaves) { + free_to_pcs_bulk(s, size, p); + return; + } + do { struct detached_freelist df; @@ -5151,7 +5928,7 @@ static int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, int kmem_cache_alloc_bulk_noprof(struct kmem_cache *s, gfp_t flags, size_t size, void **p) { - int i; + unsigned int i = 0; if (!size) return 0; @@ -5160,9 +5937,21 @@ int kmem_cache_alloc_bulk_noprof(struct kmem_cache *s, gfp_t flags, size_t size, if (unlikely(!s)) return 0; - i = __kmem_cache_alloc_bulk(s, flags, size, p); - if (unlikely(i == 0)) - return 0; + if (s->cpu_sheaves) + i = alloc_from_pcs_bulk(s, size, p); + + if (i < size) { + unsigned int j = __kmem_cache_alloc_bulk(s, flags, size - i, p + i); + /* + * If we ran out of memory, don't bother with freeing back to + * the percpu sheaves, we have bigger problems. + */ + if (unlikely(j == 0)) { + if (i > 0) + __kmem_cache_free_bulk(s, i, p); + return 0; + } + } /* * memcg and kmem_cache debug support and memory initialization. @@ -5172,11 +5961,11 @@ int kmem_cache_alloc_bulk_noprof(struct kmem_cache *s, gfp_t flags, size_t size, slab_want_init_on_alloc(flags, s), s->object_size))) { return 0; } - return i; + + return size; } EXPORT_SYMBOL(kmem_cache_alloc_bulk_noprof); - /* * Object placement in a slab is made very easy because we always start at * offset 0. If we tune the size of the object to the alignment then we can @@ -5309,8 +6098,8 @@ static inline int calculate_order(unsigned int size) return -ENOSYS; } -static void -init_kmem_cache_node(struct kmem_cache_node *n) +static bool +init_kmem_cache_node(struct kmem_cache_node *n, struct node_barn *barn) { n->nr_partial = 0; spin_lock_init(&n->list_lock); @@ -5320,6 +6109,11 @@ init_kmem_cache_node(struct kmem_cache_node *n) atomic_long_set(&n->total_objects, 0); INIT_LIST_HEAD(&n->full); #endif + n->barn = barn; + if (barn) + barn_init(barn); + + return true; } #ifndef CONFIG_SLUB_TINY @@ -5350,6 +6144,30 @@ static inline int alloc_kmem_cache_cpus(struct kmem_cache *s) } #endif /* CONFIG_SLUB_TINY */ +static int init_percpu_sheaves(struct kmem_cache *s) +{ + int cpu; + + for_each_possible_cpu(cpu) { + struct slub_percpu_sheaves *pcs; + int nid; + + pcs = per_cpu_ptr(s->cpu_sheaves, cpu); + + local_lock_init(&pcs->lock); + + nid = cpu_to_mem(cpu); + + pcs->barn = get_node(s, nid)->barn; + pcs->main = alloc_empty_sheaf(s, GFP_KERNEL); + + if (!pcs->main) + return -ENOMEM; + } + + return 0; +} + static struct kmem_cache *kmem_cache_node; /* @@ -5385,7 +6203,7 @@ static void early_kmem_cache_node_alloc(int node) slab->freelist = get_freepointer(kmem_cache_node, n); slab->inuse = 1; kmem_cache_node->node[node] = n; - init_kmem_cache_node(n); + init_kmem_cache_node(n, NULL); inc_slabs_node(kmem_cache_node, node, slab->objects); /* @@ -5401,6 +6219,13 @@ static void free_kmem_cache_nodes(struct kmem_cache *s) struct kmem_cache_node *n; for_each_kmem_cache_node(s, node, n) { + if (n->barn) { + WARN_ON(n->barn->nr_full); + WARN_ON(n->barn->nr_empty); + kfree(n->barn); + n->barn = NULL; + } + s->node[node] = NULL; kmem_cache_free(kmem_cache_node, n); } @@ -5409,6 +6234,8 @@ static void free_kmem_cache_nodes(struct kmem_cache *s) void __kmem_cache_release(struct kmem_cache *s) { cache_random_seq_destroy(s); + if (s->cpu_sheaves) + pcs_destroy(s); #ifndef CONFIG_SLUB_TINY free_percpu(s->cpu_slab); #endif @@ -5421,20 +6248,27 @@ static int init_kmem_cache_nodes(struct kmem_cache *s) for_each_node_mask(node, slab_nodes) { struct kmem_cache_node *n; + struct node_barn *barn = NULL; if (slab_state == DOWN) { early_kmem_cache_node_alloc(node); continue; } + + if (s->cpu_sheaves) { + barn = kmalloc_node(sizeof(*barn), GFP_KERNEL, node); + + if (!barn) + return 0; + } + n = kmem_cache_alloc_node(kmem_cache_node, GFP_KERNEL, node); - - if (!n) { - free_kmem_cache_nodes(s); + if (!n) return 0; - } - init_kmem_cache_node(n); + init_kmem_cache_node(n, barn); + s->node[node] = n; } return 1; @@ -5690,6 +6524,8 @@ int __kmem_cache_shutdown(struct kmem_cache *s) flush_all_cpus_locked(s); /* Attempt to free all objects */ for_each_kmem_cache_node(s, node, n) { + if (n->barn) + barn_shrink(s, n->barn); free_partial(s, n); if (n->nr_partial || node_nr_slabs(n)) return 1; @@ -5893,6 +6729,9 @@ static int __kmem_cache_do_shrink(struct kmem_cache *s) for (i = 0; i < SHRINK_PROMOTE_MAX; i++) INIT_LIST_HEAD(promote + i); + if (n->barn) + barn_shrink(s, n->barn); + spin_lock_irqsave(&n->list_lock, flags); /* @@ -6005,12 +6844,24 @@ static int slab_mem_going_online_callback(void *arg) */ mutex_lock(&slab_mutex); list_for_each_entry(s, &slab_caches, list) { + struct node_barn *barn = NULL; + /* * The structure may already exist if the node was previously * onlined and offlined. */ if (get_node(s, nid)) continue; + + if (s->cpu_sheaves) { + barn = kmalloc_node(sizeof(*barn), GFP_KERNEL, nid); + + if (!barn) { + ret = -ENOMEM; + goto out; + } + } + /* * XXX: kmem_cache_alloc_node will fallback to other nodes * since memory is not yet available from the node that @@ -6021,7 +6872,9 @@ static int slab_mem_going_online_callback(void *arg) ret = -ENOMEM; goto out; } - init_kmem_cache_node(n); + + init_kmem_cache_node(n, barn); + s->node[nid] = n; } /* @@ -6240,6 +7093,16 @@ int do_kmem_cache_create(struct kmem_cache *s, const char *name, set_cpu_partial(s); + if (args->sheaf_capacity) { + s->cpu_sheaves = alloc_percpu(struct slub_percpu_sheaves); + if (!s->cpu_sheaves) { + err = -ENOMEM; + goto out; + } + // TODO: increase capacity to grow slab_sheaf up to next kmalloc size? + s->sheaf_capacity = args->sheaf_capacity; + } + #ifdef CONFIG_NUMA s->remote_node_defrag_ratio = 1000; #endif @@ -6256,6 +7119,12 @@ int do_kmem_cache_create(struct kmem_cache *s, const char *name, if (!alloc_kmem_cache_cpus(s)) goto out; + if (s->cpu_sheaves) { + err = init_percpu_sheaves(s); + if (err) + goto out; + } + err = 0; /* Mutex is not taken during early boot */ @@ -6277,7 +7146,6 @@ int do_kmem_cache_create(struct kmem_cache *s, const char *name, __kmem_cache_release(s); return err; } - #ifdef SLAB_SUPPORTS_SYSFS static int count_inuse(struct slab *slab) { @@ -7055,8 +7923,10 @@ static ssize_t text##_store(struct kmem_cache *s, \ } \ SLAB_ATTR(text); \ +STAT_ATTR(ALLOC_PCS, alloc_cpu_sheaf); STAT_ATTR(ALLOC_FASTPATH, alloc_fastpath); STAT_ATTR(ALLOC_SLOWPATH, alloc_slowpath); +STAT_ATTR(FREE_PCS, free_cpu_sheaf); STAT_ATTR(FREE_FASTPATH, free_fastpath); STAT_ATTR(FREE_SLOWPATH, free_slowpath); STAT_ATTR(FREE_FROZEN, free_frozen); @@ -7081,6 +7951,12 @@ STAT_ATTR(CPU_PARTIAL_ALLOC, cpu_partial_alloc); STAT_ATTR(CPU_PARTIAL_FREE, cpu_partial_free); STAT_ATTR(CPU_PARTIAL_NODE, cpu_partial_node); STAT_ATTR(CPU_PARTIAL_DRAIN, cpu_partial_drain); +STAT_ATTR(SHEAF_FLUSH_MAIN, sheaf_flush_main); +STAT_ATTR(SHEAF_FLUSH_OTHER, sheaf_flush_other); +STAT_ATTR(SHEAF_REFILL, sheaf_refill); +STAT_ATTR(SHEAF_SWAP, sheaf_swap); +STAT_ATTR(SHEAF_ALLOC, sheaf_alloc); +STAT_ATTR(SHEAF_FREE, sheaf_free); #endif /* CONFIG_SLUB_STATS */ #ifdef CONFIG_KFENCE @@ -7142,8 +8018,10 @@ static struct attribute *slab_attrs[] = { &remote_node_defrag_ratio_attr.attr, #endif #ifdef CONFIG_SLUB_STATS + &alloc_cpu_sheaf_attr.attr, &alloc_fastpath_attr.attr, &alloc_slowpath_attr.attr, + &free_cpu_sheaf_attr.attr, &free_fastpath_attr.attr, &free_slowpath_attr.attr, &free_frozen_attr.attr, @@ -7168,6 +8046,12 @@ static struct attribute *slab_attrs[] = { &cpu_partial_free_attr.attr, &cpu_partial_node_attr.attr, &cpu_partial_drain_attr.attr, + &sheaf_flush_main_attr.attr, + &sheaf_flush_other_attr.attr, + &sheaf_refill_attr.attr, + &sheaf_swap_attr.attr, + &sheaf_alloc_attr.attr, + &sheaf_free_attr.attr, #endif #ifdef CONFIG_FAILSLAB &failslab_attr.attr, From patchwork Fri Feb 14 16:27:38 2025 Content-Type: text/plain; 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Fri, 14 Feb 2025 16:27:42 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id OMmlHP5ur2eHSAAAD6G6ig (envelope-from ); Fri, 14 Feb 2025 16:27:42 +0000 From: Vlastimil Babka Date: Fri, 14 Feb 2025 17:27:38 +0100 Subject: [PATCH RFC v2 02/10] slab: add sheaf support for batching kfree_rcu() operations Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250214-slub-percpu-caches-v2-2-88592ee0966a@suse.cz> References: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> In-Reply-To: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> To: Suren Baghdasaryan , "Liam R. Howlett" , Christoph Lameter , David Rientjes Cc: Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Uladzislau Rezki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, maple-tree@lists.infradead.org, Vlastimil Babka X-Mailer: b4 0.14.2 X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Spam-Level: X-Spamd-Result: default: False [-4.00 / 50.00]; REPLY(-4.00)[]; TAGGED_RCPT(0.00)[] X-Spam-Score: -4.00 X-Spam-Flag: NO X-Rspamd-Queue-Id: 931FD2117C X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Action: no action X-Rspamd-Server: rspamd2.dmz-prg2.suse.org Extend the sheaf infrastructure for more efficient kfree_rcu() handling. For caches with sheaves, on each cpu maintain a rcu_free sheaf in addition to main and spare sheaves. kfree_rcu() operations will try to put objects on this sheaf. Once full, the sheaf is detached and submitted to call_rcu() with a handler that will try to put in in the barn, or flush to slab pages using bulk free, when the barn is full. Then a new empty sheaf must be obtained to put more objects there. It's possible that no free sheaves are available to use for a new rcu_free sheaf, and the allocation in kfree_rcu() context can only use GFP_NOWAIT and thus may fail. In that case, fall back to the existing kfree_rcu() machinery. Expected advantages: - batching the kfree_rcu() operations, that could eventually replace the existing batching - sheaves can be reused for allocations via barn instead of being flushed to slabs, which is more efficient - this includes cases where only some cpus are allowed to process rcu callbacks (Android) Possible disadvantage: - objects might be waiting for more than their grace period (it is determined by the last object freed into the sheaf), increasing memory usage - but the existing batching does that too? Only implement this for CONFIG_KVFREE_RCU_BATCHED as the tiny implementation favors smaller memory footprint over performance. Signed-off-by: Vlastimil Babka --- mm/slab.h | 2 + mm/slab_common.c | 21 ++++++++ mm/slub.c | 151 +++++++++++++++++++++++++++++++++++++++++++++++++++++-- 3 files changed, 170 insertions(+), 4 deletions(-) diff --git a/mm/slab.h b/mm/slab.h index 8daaec53b6ecfc44171191d421adb12e5cba2c58..94e9959e1aefa350d3d74e3f5309fde7a5cf2ec8 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -459,6 +459,8 @@ static inline bool is_kmalloc_normal(struct kmem_cache *s) return !(s->flags & (SLAB_CACHE_DMA|SLAB_ACCOUNT|SLAB_RECLAIM_ACCOUNT)); } +bool __kfree_rcu_sheaf(struct kmem_cache *s, void *obj); + /* Legal flag mask for kmem_cache_create(), for various configurations */ #define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA | \ SLAB_CACHE_DMA32 | SLAB_PANIC | \ diff --git a/mm/slab_common.c b/mm/slab_common.c index ceeefb287899a82f30ad79b403556001c1860311..c6853450ed74160cfcb497c09f92c1f9f7b12629 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1613,6 +1613,24 @@ static void kfree_rcu_work(struct work_struct *work) kvfree_rcu_list(head); } +static bool kfree_rcu_sheaf(void *obj) +{ + struct kmem_cache *s; + struct folio *folio; + struct slab *slab; + + folio = virt_to_folio(obj); + if (unlikely(!folio_test_slab(folio))) + return false; + + slab = folio_slab(folio); + s = slab->slab_cache; + if (s->cpu_sheaves) + return __kfree_rcu_sheaf(s, obj); + + return false; +} + static bool need_offload_krc(struct kfree_rcu_cpu *krcp) { @@ -1957,6 +1975,9 @@ void kvfree_call_rcu(struct rcu_head *head, void *ptr) if (!head) might_sleep(); + if (kfree_rcu_sheaf(ptr)) + return; + // Queue the object but don't yet schedule the batch. if (debug_rcu_head_queue(ptr)) { // Probable double kfree_rcu(), just leak. diff --git a/mm/slub.c b/mm/slub.c index c06734912972b799f537359f7fe6a750918ffe9e..40175747212fefb27137309b27571abe8d0966e2 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -350,6 +350,8 @@ enum stat_item { ALLOC_FASTPATH, /* Allocation from cpu slab */ ALLOC_SLOWPATH, /* Allocation by getting a new cpu slab */ FREE_PCS, /* Free to percpu sheaf */ + FREE_RCU_SHEAF, /* Free to rcu_free sheaf */ + FREE_RCU_SHEAF_FAIL, /* Failed to free to a rcu_free sheaf */ FREE_FASTPATH, /* Free to cpu slab */ FREE_SLOWPATH, /* Freeing not to cpu slab */ FREE_FROZEN, /* Freeing to frozen slab */ @@ -2569,6 +2571,24 @@ static void sheaf_flush(struct kmem_cache *s, struct slab_sheaf *sheaf) sheaf->size = 0; } +static void __rcu_free_sheaf_prepare(struct kmem_cache *s, + struct slab_sheaf *sheaf); + +static void rcu_free_sheaf_nobarn(struct rcu_head *head) +{ + struct slab_sheaf *sheaf; + struct kmem_cache *s; + + sheaf = container_of(head, struct slab_sheaf, rcu_head); + s = sheaf->cache; + + __rcu_free_sheaf_prepare(s, sheaf); + + sheaf_flush(s, sheaf); + + free_empty_sheaf(s, sheaf); +} + /* * Caller needs to make sure migration is disabled in order to fully flush * single cpu's sheaves @@ -2598,8 +2618,8 @@ static void pcs_flush_all(struct kmem_cache *s) free_empty_sheaf(s, spare); } - // TODO: handle rcu_free - BUG_ON(rcu_free); + if (rcu_free) + call_rcu(&rcu_free->rcu_head, rcu_free_sheaf_nobarn); sheaf_flush_main(s); } @@ -2616,8 +2636,10 @@ static void __pcs_flush_all_cpu(struct kmem_cache *s, unsigned int cpu) pcs->spare = NULL; } - // TODO: handle rcu_free - BUG_ON(pcs->rcu_free); + if (pcs->rcu_free) { + call_rcu(&pcs->rcu_free->rcu_head, rcu_free_sheaf_nobarn); + pcs->rcu_free = NULL; + } sheaf_flush_main(s); } @@ -5192,6 +5214,118 @@ void free_to_pcs(struct kmem_cache *s, void *object) stat(s, FREE_PCS); } +static void __rcu_free_sheaf_prepare(struct kmem_cache *s, + struct slab_sheaf *sheaf) +{ + bool init = slab_want_init_on_free(s); + void **p = &sheaf->objects[0]; + unsigned int i = 0; + + while (i < sheaf->size) { + struct slab *slab = virt_to_slab(p[i]); + + memcg_slab_free_hook(s, slab, p + i, 1); + alloc_tagging_slab_free_hook(s, slab, p + i, 1); + + if (unlikely(!slab_free_hook(s, p[i], init, false))) { + p[i] = p[--sheaf->size]; + continue; + } + + i++; + } +} + +static void rcu_free_sheaf(struct rcu_head *head) +{ + struct slab_sheaf *sheaf; + struct node_barn *barn; + struct kmem_cache *s; + + sheaf = container_of(head, struct slab_sheaf, rcu_head); + + s = sheaf->cache; + + __rcu_free_sheaf_prepare(s, sheaf); + + barn = get_node(s, numa_mem_id())->barn; + + /* due to slab_free_hook() */ + if (unlikely(sheaf->size == 0)) + goto empty; + + if (!barn_put_full_sheaf(barn, sheaf, false)) + return; + + sheaf_flush(s, sheaf); + +empty: + if (!barn_put_empty_sheaf(barn, sheaf, false)) + return; + + free_empty_sheaf(s, sheaf); +} + +bool __kfree_rcu_sheaf(struct kmem_cache *s, void *obj) +{ + struct slub_percpu_sheaves *pcs; + struct slab_sheaf *rcu_sheaf; + unsigned long flags; + + local_lock_irqsave(&s->cpu_sheaves->lock, flags); + pcs = this_cpu_ptr(s->cpu_sheaves); + + if (unlikely(!pcs->rcu_free)) { + + struct slab_sheaf *empty; + + empty = barn_get_empty_sheaf(pcs->barn); + + if (empty) { + pcs->rcu_free = empty; + goto do_free; + } + + local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + + empty = alloc_empty_sheaf(s, GFP_NOWAIT); + + if (!empty) { + stat(s, FREE_RCU_SHEAF_FAIL); + return false; + } + + local_lock_irqsave(&s->cpu_sheaves->lock, flags); + pcs = this_cpu_ptr(s->cpu_sheaves); + + if (unlikely(pcs->rcu_free)) + barn_put_empty_sheaf(pcs->barn, empty, true); + else + pcs->rcu_free = empty; + } + +do_free: + + rcu_sheaf = pcs->rcu_free; + + rcu_sheaf->objects[rcu_sheaf->size++] = obj; + + if (likely(rcu_sheaf->size < s->sheaf_capacity)) { + local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + stat(s, FREE_RCU_SHEAF); + return true; + } + + pcs->rcu_free = NULL; + local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + + call_rcu(&rcu_sheaf->rcu_head, rcu_free_sheaf); + + stat(s, FREE_RCU_SHEAF); + + return true; +} + /* * Bulk free objects to the percpu sheaves. * Unlike free_to_pcs() this includes the calls to all necessary hooks @@ -6522,6 +6656,11 @@ int __kmem_cache_shutdown(struct kmem_cache *s) struct kmem_cache_node *n; flush_all_cpus_locked(s); + + /* we might have rcu sheaves in flight */ + if (s->cpu_sheaves) + rcu_barrier(); + /* Attempt to free all objects */ for_each_kmem_cache_node(s, node, n) { if (n->barn) @@ -7927,6 +8066,8 @@ STAT_ATTR(ALLOC_PCS, alloc_cpu_sheaf); STAT_ATTR(ALLOC_FASTPATH, alloc_fastpath); STAT_ATTR(ALLOC_SLOWPATH, alloc_slowpath); STAT_ATTR(FREE_PCS, free_cpu_sheaf); +STAT_ATTR(FREE_RCU_SHEAF, free_rcu_sheaf); +STAT_ATTR(FREE_RCU_SHEAF_FAIL, free_rcu_sheaf_fail); 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Fri, 14 Feb 2025 16:27:42 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id qMYyIv5ur2eHSAAAD6G6ig (envelope-from ); Fri, 14 Feb 2025 16:27:42 +0000 From: Vlastimil Babka Date: Fri, 14 Feb 2025 17:27:39 +0100 Subject: [PATCH RFC v2 03/10] locking/local_lock: Introduce localtry_lock_t Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250214-slub-percpu-caches-v2-3-88592ee0966a@suse.cz> References: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> In-Reply-To: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> To: Suren Baghdasaryan , "Liam R. Howlett" , Christoph Lameter , David Rientjes Cc: Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Uladzislau Rezki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, maple-tree@lists.infradead.org, Sebastian Andrzej Siewior , Alexei Starovoitov , Vlastimil Babka X-Mailer: b4 0.14.2 X-Spam-Level: X-Spamd-Result: default: False [-6.80 / 50.00]; REPLY(-4.00)[]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; TAGGED_RCPT(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; RCPT_COUNT_TWELVE(0.00)[14]; RCVD_TLS_ALL(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[linux.dev,gmail.com,kvack.org,vger.kernel.org,lists.infradead.org,linutronix.de,kernel.org,suse.cz]; R_RATELIMIT(0.00)[to_ip_from(RLtz7ce9b89hw8xzamye9qeynd)]; FROM_EQ_ENVFROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.cz:email,suse.cz:mid] X-Spam-Score: -6.80 X-Spam-Flag: NO From: Sebastian Andrzej Siewior In !PREEMPT_RT local_lock_irqsave() disables interrupts to protect critical section, but it doesn't prevent NMI, so the fully reentrant code cannot use local_lock_irqsave() for exclusive access. Introduce localtry_lock_t and localtry_lock_irqsave() that disables interrupts and sets acquired=1, so localtry_lock_irqsave() from NMI attempting to acquire the same lock will return false. In PREEMPT_RT local_lock_irqsave() maps to preemptible spin_lock(). Map localtry_lock_irqsave() to preemptible spin_trylock(). When in hard IRQ or NMI return false right away, since spin_trylock() is not safe due to PI issues. Note there is no need to use local_inc for acquired variable, since it's a percpu variable with strict nesting scopes. Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Alexei Starovoitov Signed-off-by: Vlastimil Babka --- include/linux/local_lock.h | 59 +++++++++++++++++ include/linux/local_lock_internal.h | 123 ++++++++++++++++++++++++++++++++++++ 2 files changed, 182 insertions(+) diff --git a/include/linux/local_lock.h b/include/linux/local_lock.h index 091dc0b6bdfb9f4721f94d19828a38fbfa59346c..05c254a5d7d3e6db64d7f81a3a4a10f5a942c29e 100644 --- a/include/linux/local_lock.h +++ b/include/linux/local_lock.h @@ -51,6 +51,65 @@ #define local_unlock_irqrestore(lock, flags) \ __local_unlock_irqrestore(lock, flags) +/** + * localtry_lock_init - Runtime initialize a lock instance + */ +#define localtry_lock_init(lock) __localtry_lock_init(lock) + +/** + * localtry_lock - Acquire a per CPU local lock + * @lock: The lock variable + */ +#define localtry_lock(lock) __localtry_lock(lock) + +/** + * localtry_lock_irq - Acquire a per CPU local lock and disable interrupts + * @lock: The lock variable + */ +#define localtry_lock_irq(lock) __localtry_lock_irq(lock) + +/** + * localtry_lock_irqsave - Acquire a per CPU local lock, save and disable + * interrupts + * @lock: The lock variable + * @flags: Storage for interrupt flags + */ +#define localtry_lock_irqsave(lock, flags) \ + __localtry_lock_irqsave(lock, flags) + +/** + * localtry_trylock_irqsave - Try to acquire a per CPU local lock, save and disable + * interrupts if acquired + * @lock: The lock variable + * @flags: Storage for interrupt flags + * + * The function can be used in any context such as NMI or HARDIRQ. Due to + * locking constrains it will _always_ fail to acquire the lock on PREEMPT_RT. + */ +#define localtry_trylock_irqsave(lock, flags) \ + __localtry_trylock_irqsave(lock, flags) + +/** + * local_unlock - Release a per CPU local lock + * @lock: The lock variable + */ +#define localtry_unlock(lock) __localtry_unlock(lock) + +/** + * local_unlock_irq - Release a per CPU local lock and enable interrupts + * @lock: The lock variable + */ +#define localtry_unlock_irq(lock) __localtry_unlock_irq(lock) + +/** + * localtry_unlock_irqrestore - Release a per CPU local lock and restore + * interrupt flags + * @lock: The lock variable + * @flags: Interrupt flags to restore + */ +#define localtry_unlock_irqrestore(lock, flags) \ + __localtry_unlock_irqrestore(lock, flags) + DEFINE_GUARD(local_lock, local_lock_t __percpu*, local_lock(_T), local_unlock(_T)) diff --git a/include/linux/local_lock_internal.h b/include/linux/local_lock_internal.h index 8dd71fbbb6d2b6748969438c4642f7d970834871..c1369b300777d3ff3700cfd8bd4de8186124f036 100644 --- a/include/linux/local_lock_internal.h +++ b/include/linux/local_lock_internal.h @@ -15,6 +15,11 @@ typedef struct { #endif } local_lock_t; +typedef struct { + local_lock_t llock; + unsigned int acquired; +} localtry_lock_t; + #ifdef CONFIG_DEBUG_LOCK_ALLOC # define LOCAL_LOCK_DEBUG_INIT(lockname) \ .dep_map = { \ @@ -31,6 +36,13 @@ static inline void local_lock_acquire(local_lock_t *l) l->owner = current; } +static inline void local_trylock_acquire(local_lock_t *l) +{ + lock_map_acquire_try(&l->dep_map); + DEBUG_LOCKS_WARN_ON(l->owner); + l->owner = current; +} + static inline void local_lock_release(local_lock_t *l) { DEBUG_LOCKS_WARN_ON(l->owner != current); @@ -45,11 +57,13 @@ static inline void local_lock_debug_init(local_lock_t *l) #else /* CONFIG_DEBUG_LOCK_ALLOC */ # define LOCAL_LOCK_DEBUG_INIT(lockname) static inline void local_lock_acquire(local_lock_t *l) { } +static inline void local_trylock_acquire(local_lock_t *l) { } static inline void local_lock_release(local_lock_t *l) { } static inline void local_lock_debug_init(local_lock_t *l) { } #endif /* !CONFIG_DEBUG_LOCK_ALLOC */ #define INIT_LOCAL_LOCK(lockname) { LOCAL_LOCK_DEBUG_INIT(lockname) } +#define INIT_LOCALTRY_LOCK(lockname) { .llock = { LOCAL_LOCK_DEBUG_INIT(lockname.llock) }} #define __local_lock_init(lock) \ do { \ @@ -118,6 +132,86 @@ do { \ #define __local_unlock_nested_bh(lock) \ local_lock_release(this_cpu_ptr(lock)) +/* localtry_lock_t variants */ + +#define __localtry_lock_init(lock) \ +do { \ + __local_lock_init(&(lock)->llock); \ + WRITE_ONCE(&(lock)->acquired, 0); \ +} while (0) + +#define __localtry_lock(lock) \ + do { \ + localtry_lock_t *lt; \ + preempt_disable(); \ + lt = this_cpu_ptr(lock); \ + local_lock_acquire(<->llock); \ + WRITE_ONCE(lt->acquired, 1); \ + } while (0) + +#define __localtry_lock_irq(lock) \ + do { \ + localtry_lock_t *lt; \ + local_irq_disable(); \ + lt = this_cpu_ptr(lock); \ + local_lock_acquire(<->llock); \ + WRITE_ONCE(lt->acquired, 1); \ + } while (0) + +#define __localtry_lock_irqsave(lock, flags) \ + do { \ + localtry_lock_t *lt; \ + local_irq_save(flags); \ + lt = this_cpu_ptr(lock); \ + local_lock_acquire(<->llock); \ + WRITE_ONCE(lt->acquired, 1); \ + } while (0) + +#define __localtry_trylock_irqsave(lock, flags) \ + ({ \ + localtry_lock_t *lt; \ + bool _ret; \ + \ + local_irq_save(flags); \ + lt = this_cpu_ptr(lock); \ + if (!READ_ONCE(lt->acquired)) { \ + WRITE_ONCE(lt->acquired, 1); \ + local_trylock_acquire(<->llock); \ + _ret = true; \ + } else { \ + _ret = false; \ + local_irq_restore(flags); \ + } \ + _ret; \ + }) + +#define __localtry_unlock(lock) \ + do { \ + localtry_lock_t *lt; \ + lt = this_cpu_ptr(lock); \ + WRITE_ONCE(lt->acquired, 0); \ + local_lock_release(<->llock); \ + preempt_enable(); \ + } while (0) + +#define __localtry_unlock_irq(lock) \ + do { \ + localtry_lock_t *lt; \ + lt = this_cpu_ptr(lock); \ + WRITE_ONCE(lt->acquired, 0); \ + local_lock_release(<->llock); \ + local_irq_enable(); \ + } while (0) + +#define __localtry_unlock_irqrestore(lock, flags) \ + do { \ + localtry_lock_t *lt; \ + lt = this_cpu_ptr(lock); \ + WRITE_ONCE(lt->acquired, 0); \ + local_lock_release(<->llock); \ + local_irq_restore(flags); \ + } while (0) + #else /* !CONFIG_PREEMPT_RT */ /* @@ -125,8 +219,10 @@ do { \ * critical section while staying preemptible. */ typedef spinlock_t local_lock_t; +typedef spinlock_t localtry_lock_t; #define INIT_LOCAL_LOCK(lockname) __LOCAL_SPIN_LOCK_UNLOCKED((lockname)) +#define INIT_LOCALTRY_LOCK(lockname) INIT_LOCAL_LOCK(lockname) #define __local_lock_init(l) \ do { \ @@ -169,4 +265,31 @@ do { \ spin_unlock(this_cpu_ptr((lock))); \ } while (0) +/* localtry_lock_t variants */ + +#define __localtry_lock_init(lock) __local_lock_init(lock) +#define __localtry_lock(lock) __local_lock(lock) +#define __localtry_lock_irq(lock) __local_lock(lock) +#define __localtry_lock_irqsave(lock, flags) __local_lock_irqsave(lock, flags) +#define __localtry_unlock(lock) __local_unlock(lock) +#define __localtry_unlock_irq(lock) __local_unlock(lock) +#define __localtry_unlock_irqrestore(lock, flags) __local_unlock_irqrestore(lock, flags) + +#define __localtry_trylock_irqsave(lock, flags) \ + ({ \ + int __locked; \ + \ + typecheck(unsigned long, flags); \ + flags = 0; \ + if (in_nmi() | in_hardirq()) { \ + __locked = 0; \ + } else { \ + migrate_disable(); \ + __locked = spin_trylock(this_cpu_ptr((lock))); \ + if (!__locked) \ + migrate_enable(); \ + } \ + __locked; \ + }) + #endif /* CONFIG_PREEMPT_RT */ From patchwork Fri Feb 14 16:27:40 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 13975236 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BABA9267B6D for ; 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Fri, 14 Feb 2025 16:27:42 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id QBvhJ/5ur2eHSAAAD6G6ig (envelope-from ); Fri, 14 Feb 2025 16:27:42 +0000 From: Vlastimil Babka Date: Fri, 14 Feb 2025 17:27:40 +0100 Subject: [PATCH RFC v2 04/10] locking/local_lock: add localtry_trylock() Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250214-slub-percpu-caches-v2-4-88592ee0966a@suse.cz> References: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> In-Reply-To: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> To: Suren Baghdasaryan , "Liam R. Howlett" , Christoph Lameter , David Rientjes Cc: Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Uladzislau Rezki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, maple-tree@lists.infradead.org, Vlastimil Babka X-Mailer: b4 0.14.2 X-Spam-Score: -6.80 X-Spamd-Result: default: False [-6.80 / 50.00]; REPLY(-4.00)[]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; TAGGED_RCPT(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; RCPT_COUNT_TWELVE(0.00)[12]; RCVD_COUNT_TWO(0.00)[2]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FREEMAIL_CC(0.00)[linux.dev,gmail.com,kvack.org,vger.kernel.org,lists.infradead.org,suse.cz]; R_RATELIMIT(0.00)[to_ip_from(RLtz7ce9b89hw8xzamye9qeynd)]; RCVD_TLS_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.cz:mid,suse.cz:email] X-Spam-Flag: NO X-Spam-Level: Add a localtry_trylock() variant without _irqsave that will be used in slab sheaves implementation. Thanks to only disabling preemption and not irqs, it has a lower overhead. It's not necessary to disable irqs to avoid a deadlock if the irq context uses trylock and can handle failures. Also make the comment of localtry_trylock() more clear, and fix a compilation failure in localtry_lock_init(). Signed-off-by: Vlastimil Babka --- include/linux/local_lock.h | 13 ++++++++++++- include/linux/local_lock_internal.h | 31 +++++++++++++++++++++++++++---- 2 files changed, 39 insertions(+), 5 deletions(-) diff --git a/include/linux/local_lock.h b/include/linux/local_lock.h index 05c254a5d7d3e6db64d7f81a3a4a10f5a942c29e..1a0bc35839e360d5c8170105849c3883463852f8 100644 --- a/include/linux/local_lock.h +++ b/include/linux/local_lock.h @@ -77,6 +77,16 @@ #define localtry_lock_irqsave(lock, flags) \ __localtry_lock_irqsave(lock, flags) +/** + * localtry_trylock - Try to acquire a per CPU local lock. + * @lock: The lock variable + * + * The function can be used in any context such as NMI or HARDIRQ. Due to + * locking constrains it will _always_ fail to acquire the lock in NMI or + * HARDIRQ context on PREEMPT_RT. + */ +#define localtry_trylock(lock) __localtry_trylock(lock) + /** * localtry_trylock_irqsave - Try to acquire a per CPU local lock, save and disable * interrupts if acquired @@ -84,7 +94,8 @@ * @flags: Storage for interrupt flags * * The function can be used in any context such as NMI or HARDIRQ. Due to - * locking constrains it will _always_ fail to acquire the lock on PREEMPT_RT. + * locking constrains it will _always_ fail to acquire the lock in NMI or + * HARDIRQ context on PREEMPT_RT. */ #define localtry_trylock_irqsave(lock, flags) \ __localtry_trylock_irqsave(lock, flags) diff --git a/include/linux/local_lock_internal.h b/include/linux/local_lock_internal.h index c1369b300777d3ff3700cfd8bd4de8186124f036..67bd13d142fac39bc0f8b2c05eaf81717ff480f9 100644 --- a/include/linux/local_lock_internal.h +++ b/include/linux/local_lock_internal.h @@ -137,7 +137,7 @@ do { \ #define __localtry_lock_init(lock) \ do { \ __local_lock_init(&(lock)->llock); \ - WRITE_ONCE(&(lock)->acquired, 0); \ + WRITE_ONCE((lock)->acquired, 0); \ } while (0) #define __localtry_lock(lock) \ @@ -167,6 +167,24 @@ do { \ WRITE_ONCE(lt->acquired, 1); \ } while (0) +#define __localtry_trylock(lock) \ + ({ \ + localtry_lock_t *lt; \ + bool _ret; \ + \ + preempt_disable(); \ + lt = this_cpu_ptr(lock); \ + if (!READ_ONCE(lt->acquired)) { \ + WRITE_ONCE(lt->acquired, 1); \ + local_trylock_acquire(<->llock); \ + _ret = true; \ + } else { \ + _ret = false; \ + preempt_enable(); \ + } \ + _ret; \ + }) + #define __localtry_trylock_irqsave(lock, flags) \ ({ \ localtry_lock_t *lt; \ @@ -275,12 +293,10 @@ do { \ #define __localtry_unlock_irq(lock) __local_unlock(lock) #define __localtry_unlock_irqrestore(lock, flags) __local_unlock_irqrestore(lock, flags) -#define __localtry_trylock_irqsave(lock, flags) \ +#define __localtry_trylock(lock) \ ({ \ int __locked; \ \ - typecheck(unsigned long, flags); \ - flags = 0; \ if (in_nmi() | in_hardirq()) { \ __locked = 0; \ } else { \ @@ -292,4 +308,11 @@ do { \ __locked; \ }) +#define __localtry_trylock_irqsave(lock, flags) \ + ({ \ + typecheck(unsigned long, flags); \ + flags = 0; \ + __localtry_trylock(lock); \ + }) + #endif /* CONFIG_PREEMPT_RT */ From patchwork Fri Feb 14 16:27:41 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 13975232 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 722381E04AC for ; Fri, 14 Feb 2025 16:27:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.131 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739550472; cv=none; b=N/1tvw8e2uPzYnQ2+f1hLzhU431b8SgiBKJ+CPvdIxqiARcfdQ105ryJ+hE/eV/qK+a7d6fY1IXrqxPFwMsIYEyzEDtdVmPGOsvZgNIVVDAHbSi0FoncaT6qJt0InMuotTuR4Alyebw5QvtKd09Uam9hJuIK3M7mte/S7plAsDo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739550472; c=relaxed/simple; bh=mRPFid06NgIdjdVbiBZAXkBK2kT2FnvoPAgernzWSi4=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=na7CL7s/1+lh+qFnOuFSRGLtVonimChkvTEnThTCl62tNZ++CSI+OYOxMu3yf3HxciV5BcZ1YewdPRvf5bvhaRabMSaY9jbagf6HRlVXjogA/HbMESjcaSC6xUVPsCteSr7I1ckwpSygE8Nd/9jKzYeydMuEnXnb4Q56eRi6Uvs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz; spf=fail smtp.mailfrom=suse.cz; arc=none smtp.client-ip=195.135.223.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=suse.cz Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id D0C8B1F391; Fri, 14 Feb 2025 16:27:42 +0000 (UTC) Authentication-Results: smtp-out2.suse.de; none Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id B7FB813AF0; Fri, 14 Feb 2025 16:27:42 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id +NqlLP5ur2eHSAAAD6G6ig (envelope-from ); Fri, 14 Feb 2025 16:27:42 +0000 From: Vlastimil Babka Date: Fri, 14 Feb 2025 17:27:41 +0100 Subject: [PATCH RFC v2 05/10] slab: switch percpu sheaves locking to localtry_lock Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250214-slub-percpu-caches-v2-5-88592ee0966a@suse.cz> References: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> In-Reply-To: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> To: Suren Baghdasaryan , "Liam R. Howlett" , Christoph Lameter , David Rientjes Cc: Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Uladzislau Rezki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, maple-tree@lists.infradead.org, Vlastimil Babka X-Mailer: b4 0.14.2 X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Spamd-Result: default: False [-4.00 / 50.00]; REPLY(-4.00)[]; TAGGED_RCPT(0.00)[] X-Spam-Flag: NO X-Spam-Score: -4.00 X-Rspamd-Queue-Id: D0C8B1F391 X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Action: no action X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spam-Level: Instead of local_lock_irqsave(), use localtry_trylock() when potential callers include irq context, and localtry_lock() otherwise (such as when we already know the gfp flags allow blocking). This should reduce the locking (due to irq disabling/enabling) overhead. Failing to use percpu sheaves in an irq due to preempting an already locked user of sheaves should be rare so it's a favorable tradeoff. Signed-off-by: Vlastimil Babka --- mm/slub.c | 122 ++++++++++++++++++++++++++++++++++++++------------------------ 1 file changed, 76 insertions(+), 46 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 40175747212fefb27137309b27571abe8d0966e2..3d7345e7e938d53950ed0d6abe8eb0e93cf8f5b1 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -450,7 +450,7 @@ struct slab_sheaf { }; struct slub_percpu_sheaves { - local_lock_t lock; + localtry_lock_t lock; struct slab_sheaf *main; /* never NULL when unlocked */ struct slab_sheaf *spare; /* empty or full, may be NULL */ struct slab_sheaf *rcu_free; @@ -2529,16 +2529,19 @@ static struct slab_sheaf *alloc_full_sheaf(struct kmem_cache *s, gfp_t gfp) static void __kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p); -static void sheaf_flush_main(struct kmem_cache *s) +/* returns true if at least partially flushed */ +static bool sheaf_flush_main(struct kmem_cache *s) { struct slub_percpu_sheaves *pcs; unsigned int batch, remaining; void *objects[PCS_BATCH_MAX]; struct slab_sheaf *sheaf; - unsigned long flags; + bool ret = false; next_batch: - local_lock_irqsave(&s->cpu_sheaves->lock, flags); + if (!localtry_trylock(&s->cpu_sheaves->lock)) + return ret; + pcs = this_cpu_ptr(s->cpu_sheaves); sheaf = pcs->main; @@ -2549,14 +2552,18 @@ static void sheaf_flush_main(struct kmem_cache *s) remaining = sheaf->size; - local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + localtry_unlock(&s->cpu_sheaves->lock); __kmem_cache_free_bulk(s, batch, &objects[0]); stat_add(s, SHEAF_FLUSH_MAIN, batch); + ret = true; + if (remaining) goto next_batch; + + return ret; } static void sheaf_flush(struct kmem_cache *s, struct slab_sheaf *sheaf) @@ -2593,6 +2600,8 @@ static void rcu_free_sheaf_nobarn(struct rcu_head *head) * Caller needs to make sure migration is disabled in order to fully flush * single cpu's sheaves * + * must not be called from an irq + * * flushing operations are rare so let's keep it simple and flush to slabs * directly, skipping the barn */ @@ -2600,9 +2609,8 @@ static void pcs_flush_all(struct kmem_cache *s) { struct slub_percpu_sheaves *pcs; struct slab_sheaf *spare, *rcu_free; - unsigned long flags; - local_lock_irqsave(&s->cpu_sheaves->lock, flags); + localtry_lock(&s->cpu_sheaves->lock); pcs = this_cpu_ptr(s->cpu_sheaves); spare = pcs->spare; @@ -2611,7 +2619,7 @@ static void pcs_flush_all(struct kmem_cache *s) rcu_free = pcs->rcu_free; pcs->rcu_free = NULL; - local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + localtry_unlock(&s->cpu_sheaves->lock); if (spare) { sheaf_flush(s, spare); @@ -4554,10 +4562,11 @@ static __fastpath_inline void *alloc_from_pcs(struct kmem_cache *s, gfp_t gfp) { struct slub_percpu_sheaves *pcs; - unsigned long flags; void *object; - local_lock_irqsave(&s->cpu_sheaves->lock, flags); + if (!localtry_trylock(&s->cpu_sheaves->lock)) + return NULL; + pcs = this_cpu_ptr(s->cpu_sheaves); if (unlikely(pcs->main->size == 0)) { @@ -4590,7 +4599,7 @@ void *alloc_from_pcs(struct kmem_cache *s, gfp_t gfp) } } - local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + localtry_unlock(&s->cpu_sheaves->lock); if (!can_alloc) return NULL; @@ -4612,7 +4621,11 @@ void *alloc_from_pcs(struct kmem_cache *s, gfp_t gfp) if (!full) return NULL; - local_lock_irqsave(&s->cpu_sheaves->lock, flags); + /* + * we can reach here only when gfpflags_allow_blocking + * so this must not be an irq + */ + localtry_lock(&s->cpu_sheaves->lock); pcs = this_cpu_ptr(s->cpu_sheaves); /* @@ -4646,7 +4659,7 @@ void *alloc_from_pcs(struct kmem_cache *s, gfp_t gfp) do_alloc: object = pcs->main->objects[--pcs->main->size]; - local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + localtry_unlock(&s->cpu_sheaves->lock); stat(s, ALLOC_PCS); @@ -4658,12 +4671,13 @@ unsigned int alloc_from_pcs_bulk(struct kmem_cache *s, size_t size, void **p) { struct slub_percpu_sheaves *pcs; struct slab_sheaf *main; - unsigned long flags; unsigned int allocated = 0; unsigned int batch; next_batch: - local_lock_irqsave(&s->cpu_sheaves->lock, flags); + if (!localtry_trylock(&s->cpu_sheaves->lock)) + return allocated; + pcs = this_cpu_ptr(s->cpu_sheaves); if (unlikely(pcs->main->size == 0)) { @@ -4683,7 +4697,7 @@ unsigned int alloc_from_pcs_bulk(struct kmem_cache *s, size_t size, void **p) goto do_alloc; } - local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + localtry_unlock(&s->cpu_sheaves->lock); /* * Once full sheaves in barn are depleted, let the bulk @@ -4701,7 +4715,7 @@ unsigned int alloc_from_pcs_bulk(struct kmem_cache *s, size_t size, void **p) main->size -= batch; memcpy(p, main->objects + main->size, batch * sizeof(void *)); - local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + localtry_unlock(&s->cpu_sheaves->lock); stat_add(s, ALLOC_PCS, batch); @@ -5121,13 +5135,14 @@ static void __slab_free(struct kmem_cache *s, struct slab *slab, * The object is expected to have passed slab_free_hook() already. */ static __fastpath_inline -void free_to_pcs(struct kmem_cache *s, void *object) +bool free_to_pcs(struct kmem_cache *s, void *object) { struct slub_percpu_sheaves *pcs; - unsigned long flags; restart: - local_lock_irqsave(&s->cpu_sheaves->lock, flags); + if (!localtry_trylock(&s->cpu_sheaves->lock)) + return false; + pcs = this_cpu_ptr(s->cpu_sheaves); if (unlikely(pcs->main->size == s->sheaf_capacity)) { @@ -5162,7 +5177,7 @@ void free_to_pcs(struct kmem_cache *s, void *object) struct slab_sheaf *to_flush = pcs->spare; pcs->spare = NULL; - local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + localtry_unlock(&s->cpu_sheaves->lock); sheaf_flush(s, to_flush); empty = to_flush; @@ -5170,17 +5185,27 @@ void free_to_pcs(struct kmem_cache *s, void *object) } alloc_empty: - local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + localtry_unlock(&s->cpu_sheaves->lock); empty = alloc_empty_sheaf(s, GFP_NOWAIT); if (!empty) { - sheaf_flush_main(s); - goto restart; + if (sheaf_flush_main(s)) + goto restart; + else + return false; } got_empty: - local_lock_irqsave(&s->cpu_sheaves->lock, flags); + if (!localtry_trylock(&s->cpu_sheaves->lock)) { + struct node_barn *barn; + + barn = get_node(s, numa_mem_id())->barn; + + barn_put_empty_sheaf(barn, empty, true); + return false; + } + pcs = this_cpu_ptr(s->cpu_sheaves); /* @@ -5209,9 +5234,11 @@ void free_to_pcs(struct kmem_cache *s, void *object) do_free: pcs->main->objects[pcs->main->size++] = object; - local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + localtry_unlock(&s->cpu_sheaves->lock); stat(s, FREE_PCS); + + return true; } static void __rcu_free_sheaf_prepare(struct kmem_cache *s, @@ -5270,9 +5297,10 @@ bool __kfree_rcu_sheaf(struct kmem_cache *s, void *obj) { struct slub_percpu_sheaves *pcs; struct slab_sheaf *rcu_sheaf; - unsigned long flags; - local_lock_irqsave(&s->cpu_sheaves->lock, flags); + if (!localtry_trylock(&s->cpu_sheaves->lock)) + goto fail; + pcs = this_cpu_ptr(s->cpu_sheaves); if (unlikely(!pcs->rcu_free)) { @@ -5286,16 +5314,16 @@ bool __kfree_rcu_sheaf(struct kmem_cache *s, void *obj) goto do_free; } - local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + localtry_unlock(&s->cpu_sheaves->lock); empty = alloc_empty_sheaf(s, GFP_NOWAIT); - if (!empty) { - stat(s, FREE_RCU_SHEAF_FAIL); - return false; - } + if (!empty) + goto fail; + + if (!localtry_trylock(&s->cpu_sheaves->lock)) + goto fail; - local_lock_irqsave(&s->cpu_sheaves->lock, flags); pcs = this_cpu_ptr(s->cpu_sheaves); if (unlikely(pcs->rcu_free)) @@ -5311,19 +5339,22 @@ bool __kfree_rcu_sheaf(struct kmem_cache *s, void *obj) rcu_sheaf->objects[rcu_sheaf->size++] = obj; if (likely(rcu_sheaf->size < s->sheaf_capacity)) { - local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + localtry_unlock(&s->cpu_sheaves->lock); stat(s, FREE_RCU_SHEAF); return true; } pcs->rcu_free = NULL; - local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + localtry_unlock(&s->cpu_sheaves->lock); call_rcu(&rcu_sheaf->rcu_head, rcu_free_sheaf); stat(s, FREE_RCU_SHEAF); - return true; + +fail: + stat(s, FREE_RCU_SHEAF_FAIL); + return false; } /* @@ -5335,7 +5366,6 @@ static void free_to_pcs_bulk(struct kmem_cache *s, size_t size, void **p) { struct slub_percpu_sheaves *pcs; struct slab_sheaf *main; - unsigned long flags; unsigned int batch, i = 0; bool init; @@ -5358,7 +5388,9 @@ static void free_to_pcs_bulk(struct kmem_cache *s, size_t size, void **p) } next_batch: - local_lock_irqsave(&s->cpu_sheaves->lock, flags); + if (!localtry_trylock(&s->cpu_sheaves->lock)) + goto fallback; + pcs = this_cpu_ptr(s->cpu_sheaves); if (unlikely(pcs->main->size == s->sheaf_capacity)) { @@ -5389,13 +5421,13 @@ static void free_to_pcs_bulk(struct kmem_cache *s, size_t size, void **p) } no_empty: - local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + localtry_unlock(&s->cpu_sheaves->lock); /* * if we depleted all empty sheaves in the barn or there are too * many full sheaves, free the rest to slab pages */ - +fallback: __kmem_cache_free_bulk(s, size, p); return; } @@ -5407,7 +5439,7 @@ static void free_to_pcs_bulk(struct kmem_cache *s, size_t size, void **p) memcpy(main->objects + main->size, p, batch * sizeof(void *)); main->size += batch; - local_unlock_irqrestore(&s->cpu_sheaves->lock, flags); + localtry_unlock(&s->cpu_sheaves->lock); stat_add(s, FREE_PCS, batch); @@ -5507,9 +5539,7 @@ void slab_free(struct kmem_cache *s, struct slab *slab, void *object, if (unlikely(!slab_free_hook(s, object, slab_want_init_on_free(s), false))) return; - if (s->cpu_sheaves) - free_to_pcs(s, object); - else + if (!s->cpu_sheaves || !free_to_pcs(s, object)) do_slab_free(s, slab, object, object, 1, addr); } @@ -6288,7 +6318,7 @@ static int init_percpu_sheaves(struct kmem_cache *s) pcs = per_cpu_ptr(s->cpu_sheaves, cpu); - local_lock_init(&pcs->lock); + localtry_lock_init(&pcs->lock); nid = cpu_to_mem(cpu); From patchwork Fri Feb 14 16:27:42 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 13975238 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6A8CA267F68 for ; Fri, 14 Feb 2025 16:28:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; 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Fri, 14 Feb 2025 16:27:42 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id OIBIMf5ur2eHSAAAD6G6ig (envelope-from ); Fri, 14 Feb 2025 16:27:42 +0000 From: Vlastimil Babka Date: Fri, 14 Feb 2025 17:27:42 +0100 Subject: [PATCH RFC v2 06/10] slab: sheaf prefilling for guaranteed allocations Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250214-slub-percpu-caches-v2-6-88592ee0966a@suse.cz> References: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> In-Reply-To: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> To: Suren Baghdasaryan , "Liam R. Howlett" , Christoph Lameter , David Rientjes Cc: Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Uladzislau Rezki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, maple-tree@lists.infradead.org, Vlastimil Babka X-Mailer: b4 0.14.2 X-Spam-Level: X-Spamd-Result: default: False [-6.80 / 50.00]; REPLY(-4.00)[]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; TAGGED_RCPT(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; RCPT_COUNT_TWELVE(0.00)[12]; RCVD_TLS_ALL(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[linux.dev,gmail.com,kvack.org,vger.kernel.org,lists.infradead.org,suse.cz]; R_RATELIMIT(0.00)[to_ip_from(RLtz7ce9b89hw8xzamye9qeynd)]; FROM_EQ_ENVFROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.cz:email,suse.cz:mid] X-Spam-Score: -6.80 X-Spam-Flag: NO Add functions for efficient guaranteed allocations e.g. in a critical section that cannot sleep, when the exact number of allocations is not known beforehand, but an upper limit can be calculated. kmem_cache_prefill_sheaf() returns a sheaf containing at least given number of objects. kmem_cache_alloc_from_sheaf() will allocate an object from the sheaf and is guaranteed not to fail until depleted. kmem_cache_return_sheaf() is for giving the sheaf back to the slab allocator after the critical section. This will also attempt to refill it to cache's sheaf capacity for better efficiency of sheaves handling, but it's not stricly necessary to succeed. kmem_cache_refill_sheaf() can be used to refill a previously obtained sheaf to requested size. If the current size is sufficient, it does nothing. If the requested size exceeds cache's sheaf_capacity and the sheaf's current capacity, the sheaf will be replaced with a new one, hence the indirect pointer parameter. kmem_cache_sheaf_size() can be used to query the current size. The implementation supports requesting sizes that exceed cache's sheaf_capacity, but it is not efficient - such sheaves are allocated fresh in kmem_cache_prefill_sheaf() and flushed and freed immediately by kmem_cache_return_sheaf(). kmem_cache_refill_sheaf() might be expecially ineffective when replacing a sheaf with a new one of a larger capacity. It is therefore better to size cache's sheaf_capacity accordingly. Signed-off-by: Vlastimil Babka --- include/linux/slab.h | 16 ++++ mm/slub.c | 227 +++++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 243 insertions(+) diff --git a/include/linux/slab.h b/include/linux/slab.h index 0e1b25228c77140d05b5b4433c9d7923de36ec05..dd01b67982e856b1b02f4f0e6fc557726e7f02a8 100644 --- a/include/linux/slab.h +++ b/include/linux/slab.h @@ -829,6 +829,22 @@ void *kmem_cache_alloc_node_noprof(struct kmem_cache *s, gfp_t flags, int node) __assume_slab_alignment __malloc; #define kmem_cache_alloc_node(...) alloc_hooks(kmem_cache_alloc_node_noprof(__VA_ARGS__)) +struct slab_sheaf * +kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size); + +int kmem_cache_refill_sheaf(struct kmem_cache *s, gfp_t gfp, + struct slab_sheaf **sheafp, unsigned int size); + +void kmem_cache_return_sheaf(struct kmem_cache *s, gfp_t gfp, + struct slab_sheaf *sheaf); + +void *kmem_cache_alloc_from_sheaf_noprof(struct kmem_cache *cachep, gfp_t gfp, + struct slab_sheaf *sheaf) __assume_slab_alignment __malloc; +#define kmem_cache_alloc_from_sheaf(...) \ + alloc_hooks(kmem_cache_alloc_from_sheaf_noprof(__VA_ARGS__)) + +unsigned int kmem_cache_sheaf_size(struct slab_sheaf *sheaf); + /* * These macros allow declaring a kmem_buckets * parameter alongside size, which * can be compiled out with CONFIG_SLAB_BUCKETS=n so that a large number of call diff --git a/mm/slub.c b/mm/slub.c index 3d7345e7e938d53950ed0d6abe8eb0e93cf8f5b1..c1df7cf22267f28f743404531bef921e25fac086 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -443,6 +443,8 @@ struct slab_sheaf { union { struct rcu_head rcu_head; struct list_head barn_list; + /* only used for prefilled sheafs */ + unsigned int capacity; }; struct kmem_cache *cache; unsigned int size; @@ -2735,6 +2737,30 @@ static int barn_put_full_sheaf(struct node_barn *barn, struct slab_sheaf *sheaf, return ret; } +static struct slab_sheaf *barn_get_full_or_empty_sheaf(struct node_barn *barn) +{ + struct slab_sheaf *sheaf = NULL; + unsigned long flags; + + spin_lock_irqsave(&barn->lock, flags); + + if (barn->nr_full) { + sheaf = list_first_entry(&barn->sheaves_full, struct slab_sheaf, + barn_list); + list_del(&sheaf->barn_list); + barn->nr_full--; + } else if (barn->nr_empty) { + sheaf = list_first_entry(&barn->sheaves_empty, + struct slab_sheaf, barn_list); + list_del(&sheaf->barn_list); + barn->nr_empty--; + } + + spin_unlock_irqrestore(&barn->lock, flags); + + return sheaf; +} + /* * If a full sheaf is available, return it and put the supplied empty one to * barn. We ignore the limit on empty sheaves as the number of sheaves doesn't @@ -4831,6 +4857,207 @@ void *kmem_cache_alloc_node_noprof(struct kmem_cache *s, gfp_t gfpflags, int nod } EXPORT_SYMBOL(kmem_cache_alloc_node_noprof); + +/* + * returns a sheaf that has least the requested size + * when prefilling is needed, do so with given gfp flags + * + * return NULL if sheaf allocation or prefilling failed + */ +struct slab_sheaf * +kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size) +{ + struct slub_percpu_sheaves *pcs; + struct slab_sheaf *sheaf = NULL; + + if (unlikely(size > s->sheaf_capacity)) { + sheaf = kzalloc(struct_size(sheaf, objects, size), gfp); + if (!sheaf) + return NULL; + + sheaf->cache = s; + sheaf->capacity = size; + + if (!__kmem_cache_alloc_bulk(s, gfp, size, + &sheaf->objects[0])) { + kfree(sheaf); + return NULL; + } + + sheaf->size = size; + + return sheaf; + } + + localtry_lock(&s->cpu_sheaves->lock); + pcs = this_cpu_ptr(s->cpu_sheaves); + + if (pcs->spare) { + sheaf = pcs->spare; + pcs->spare = NULL; + } + + if (!sheaf) + sheaf = barn_get_full_or_empty_sheaf(pcs->barn); + + localtry_unlock(&s->cpu_sheaves->lock); + + if (!sheaf) { + sheaf = alloc_empty_sheaf(s, gfp); + } + + if (sheaf && sheaf->size < size) { + if (refill_sheaf(s, sheaf, gfp)) { + sheaf_flush(s, sheaf); + free_empty_sheaf(s, sheaf); + sheaf = NULL; + } + } + + if (sheaf) + sheaf->capacity = s->sheaf_capacity; + + return sheaf; +} + +/* + * Use this to return a sheaf obtained by kmem_cache_prefill_sheaf() + * It tries to refill the sheaf back to the cache's sheaf_capacity + * to avoid handling partially full sheaves. + * + * If the refill fails because gfp is e.g. GFP_NOWAIT, the sheaf is + * instead dissolved + */ +void kmem_cache_return_sheaf(struct kmem_cache *s, gfp_t gfp, + struct slab_sheaf *sheaf) +{ + struct slub_percpu_sheaves *pcs; + bool refill = false; + struct node_barn *barn; + + if (unlikely(sheaf->capacity != s->sheaf_capacity)) { + sheaf_flush(s, sheaf); + kfree(sheaf); + return; + } + + localtry_lock(&s->cpu_sheaves->lock); + pcs = this_cpu_ptr(s->cpu_sheaves); + + if (!pcs->spare) { + pcs->spare = sheaf; + sheaf = NULL; + } else if (pcs->barn->nr_full >= MAX_FULL_SHEAVES) { + /* racy check */ + barn = pcs->barn; + refill = true; + } + + localtry_unlock(&s->cpu_sheaves->lock); + + if (!sheaf) + return; + + /* + * if the barn is full of full sheaves or we fail to refill the sheaf, + * simply flush and free it + */ + if (!refill || refill_sheaf(s, sheaf, gfp)) { + sheaf_flush(s, sheaf); + free_empty_sheaf(s, sheaf); + return; + } + + /* we racily determined the sheaf would fit, so now force it */ + barn_put_full_sheaf(barn, sheaf, true); +} + +/* + * refill a sheaf previously returned by kmem_cache_prefill_sheaf to at least + * the given size + * + * the sheaf might be replaced by a new one when requesting more than + * s->sheaf_capacity objects if such replacement is necessary, but the refill + * fails (with -ENOMEM), the existing sheaf is left intact + */ +int kmem_cache_refill_sheaf(struct kmem_cache *s, gfp_t gfp, + struct slab_sheaf **sheafp, unsigned int size) +{ + struct slab_sheaf *sheaf; + + /* + * TODO: do we want to support *sheaf == NULL to be equivalent of + * kmem_cache_prefill_sheaf() ? + */ + if (!sheafp || !(*sheafp)) + return -EINVAL; + + sheaf = *sheafp; + if (sheaf->size >= size) + return 0; + + if (likely(sheaf->capacity >= size)) { + if (likely(sheaf->capacity == s->sheaf_capacity)) + return refill_sheaf(s, sheaf, gfp); + + if (!__kmem_cache_alloc_bulk(s, gfp, sheaf->capacity - sheaf->size, + &sheaf->objects[sheaf->size])) { + return -ENOMEM; + } + sheaf->size = sheaf->capacity; + + return 0; + } + + /* + * We had a regular sized sheaf and need an oversize one, or we had an + * oversize one already but need a larger one now. + * This should be a very rare path so let's not complicate it. + */ + sheaf = kmem_cache_prefill_sheaf(s, gfp, size); + if (!sheaf) + return -ENOMEM; + + kmem_cache_return_sheaf(s, gfp, *sheafp); + *sheafp = sheaf; + return 0; +} + +/* + * Allocate from a sheaf obtained by kmem_cache_prefill_sheaf() + * + * Guaranteed not to fail as many allocations as was the requested size. + * After the sheaf is emptied, it fails - no fallback to the slab cache itself. + * + * The gfp parameter is meant only to specify __GFP_ZERO or __GFP_ACCOUNT + * memcg charging is forced over limit if necessary, to avoid failure. + */ +void * +kmem_cache_alloc_from_sheaf_noprof(struct kmem_cache *s, gfp_t gfp, + struct slab_sheaf *sheaf) +{ + void *ret = NULL; + bool init; + + if (sheaf->size == 0) + goto out; + + ret = sheaf->objects[--sheaf->size]; + + init = slab_want_init_on_alloc(gfp, s); + + /* add __GFP_NOFAIL to force successful memcg charging */ + slab_post_alloc_hook(s, NULL, gfp | __GFP_NOFAIL, 1, &ret, init, s->object_size); +out: + trace_kmem_cache_alloc(_RET_IP_, ret, s, gfp, NUMA_NO_NODE); + + return ret; +} + +unsigned int kmem_cache_sheaf_size(struct slab_sheaf *sheaf) +{ + return sheaf->size; +} /* * To avoid unnecessary overhead, we pass through large allocation requests * directly to the page allocator. We use __GFP_COMP, because we will need to From patchwork Fri Feb 14 16:27:43 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 13975237 Received: from smtp-out2.suse.de (smtp-out2.suse.de [195.135.223.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7A2C7267B76 for ; Fri, 14 Feb 2025 16:28:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=195.135.223.131 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739550485; cv=none; b=BoCDs92P5o6XdOLQqUAKoM7GjKYolnById3k33u2LGOc2Zm2OuV9Uz9SSupCgeJHGrHrZUYMG2Pam4z4Ss31LxcstTzUuUBnPWNnsM4TVlltLNAPX55S+gLrgaBrXn5feJNHI2rqVhwaIm+cjMI0IBz9YZOl3popnaaHsAhSdjM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1739550485; c=relaxed/simple; bh=FIhqpGQRgZX+ryUfiw2jv01IB7iYXNhxYhaPED5xW30=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=stxDXdkcThPXfJpwcuqQSNWYYWc2//p4PcdOLpSEnDcjMnlhfLz3/y3WyDfgqNkA0pKUflif7SBD+w+JPhaCWlt+lLlOmZB8jnX3G9BLMH69DgqvV1kfW48xrCU+Jo+c5a3xQZTYeo5Z2fycKSCHwUf6bhx9OKckKdjOcBuW2fU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz; spf=fail smtp.mailfrom=suse.cz; arc=none smtp.client-ip=195.135.223.131 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=suse.cz Received: from imap1.dmz-prg2.suse.org (imap1.dmz-prg2.suse.org [IPv6:2a07:de40:b281:104:10:150:64:97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id F20B31F397; Fri, 14 Feb 2025 16:27:42 +0000 (UTC) Authentication-Results: smtp-out2.suse.de; none Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id DE1DC13285; Fri, 14 Feb 2025 16:27:42 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id 2Mf3Nf5ur2eHSAAAD6G6ig (envelope-from ); Fri, 14 Feb 2025 16:27:42 +0000 From: Vlastimil Babka Date: Fri, 14 Feb 2025 17:27:43 +0100 Subject: [PATCH RFC v2 07/10] slab: determine barn status racily outside of lock Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250214-slub-percpu-caches-v2-7-88592ee0966a@suse.cz> References: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> In-Reply-To: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> To: Suren Baghdasaryan , "Liam R. Howlett" , Christoph Lameter , David Rientjes Cc: Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Uladzislau Rezki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, maple-tree@lists.infradead.org, Vlastimil Babka X-Mailer: b4 0.14.2 X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Spamd-Result: default: False [-4.00 / 50.00]; REPLY(-4.00)[]; TAGGED_RCPT(0.00)[] X-Spam-Flag: NO X-Spam-Score: -4.00 X-Rspamd-Queue-Id: F20B31F397 X-Rspamd-Pre-Result: action=no action; module=replies; Message is reply to one we originated X-Rspamd-Action: no action X-Rspamd-Server: rspamd1.dmz-prg2.suse.org X-Spam-Level: The possibility of many barn operations is determined by the current number of full or empty sheaves. Taking the barn->lock just to find out that e.g. there are no empty sheaves results in unnecessary overhead and lock contention. Thus perform these checks outside of the lock with a data_race() annotated variable read and fail quickly without taking the lock. Checks for sheaf availability that racily succeed have to be obviously repeated under the lock for correctness, but we can skip repeating checks if there are too many sheaves on the given list as the limits don't need to be strict. Signed-off-by: Vlastimil Babka --- mm/slub.c | 57 ++++++++++++++++++++++++++++++++++----------------------- 1 file changed, 34 insertions(+), 23 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index c1df7cf22267f28f743404531bef921e25fac086..72e6437f1d74bfacbb1cd7642af42929c48cc66a 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2685,9 +2685,12 @@ static struct slab_sheaf *barn_get_empty_sheaf(struct node_barn *barn) struct slab_sheaf *empty = NULL; unsigned long flags; + if (!data_race(barn->nr_empty)) + return NULL; + spin_lock_irqsave(&barn->lock, flags); - if (barn->nr_empty) { + if (likely(barn->nr_empty)) { empty = list_first_entry(&barn->sheaves_empty, struct slab_sheaf, barn_list); list_del(&empty->barn_list); @@ -2703,38 +2706,36 @@ static int barn_put_empty_sheaf(struct node_barn *barn, struct slab_sheaf *sheaf, bool ignore_limit) { unsigned long flags; - int ret = 0; + + /* we don't repeat the check under barn->lock as it's not critical */ + if (!ignore_limit && data_race(barn->nr_empty) >= MAX_EMPTY_SHEAVES) + return -E2BIG; spin_lock_irqsave(&barn->lock, flags); - if (!ignore_limit && barn->nr_empty >= MAX_EMPTY_SHEAVES) { - ret = -E2BIG; - } else { - list_add(&sheaf->barn_list, &barn->sheaves_empty); - barn->nr_empty++; - } + list_add(&sheaf->barn_list, &barn->sheaves_empty); + barn->nr_empty++; spin_unlock_irqrestore(&barn->lock, flags); - return ret; + return 0; } static int barn_put_full_sheaf(struct node_barn *barn, struct slab_sheaf *sheaf, bool ignore_limit) { unsigned long flags; - int ret = 0; + + /* we don't repeat the check under barn->lock as it's not critical */ + if (!ignore_limit && data_race(barn->nr_full) >= MAX_FULL_SHEAVES) + return -E2BIG; spin_lock_irqsave(&barn->lock, flags); - if (!ignore_limit && barn->nr_full >= MAX_FULL_SHEAVES) { - ret = -E2BIG; - } else { - list_add(&sheaf->barn_list, &barn->sheaves_full); - barn->nr_full++; - } + list_add(&sheaf->barn_list, &barn->sheaves_full); + barn->nr_full++; spin_unlock_irqrestore(&barn->lock, flags); - return ret; + return 0; } static struct slab_sheaf *barn_get_full_or_empty_sheaf(struct node_barn *barn) @@ -2742,6 +2743,9 @@ static struct slab_sheaf *barn_get_full_or_empty_sheaf(struct node_barn *barn) struct slab_sheaf *sheaf = NULL; unsigned long flags; + if (!data_race(barn->nr_full) && !data_race(barn->nr_empty)) + return NULL; + spin_lock_irqsave(&barn->lock, flags); if (barn->nr_full) { @@ -2772,9 +2776,12 @@ barn_replace_empty_sheaf(struct node_barn *barn, struct slab_sheaf *empty) struct slab_sheaf *full = NULL; unsigned long flags; + if (!data_race(barn->nr_full)) + return NULL; + spin_lock_irqsave(&barn->lock, flags); - if (barn->nr_full) { + if (likely(barn->nr_full)) { full = list_first_entry(&barn->sheaves_full, struct slab_sheaf, barn_list); list_del(&full->barn_list); @@ -2797,19 +2804,23 @@ barn_replace_full_sheaf(struct node_barn *barn, struct slab_sheaf *full) struct slab_sheaf *empty; unsigned long flags; + /* we don't repeat this check under barn->lock as it's not critical */ + if (data_race(barn->nr_full) >= MAX_FULL_SHEAVES) + return ERR_PTR(-E2BIG); + if (!data_race(barn->nr_empty)) + return ERR_PTR(-ENOMEM); + spin_lock_irqsave(&barn->lock, flags); - if (barn->nr_full >= MAX_FULL_SHEAVES) { - empty = ERR_PTR(-E2BIG); 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Fri, 14 Feb 2025 16:27:42 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id kM5IOv5ur2eHSAAAD6G6ig (envelope-from ); Fri, 14 Feb 2025 16:27:42 +0000 From: Vlastimil Babka Date: Fri, 14 Feb 2025 17:27:44 +0100 Subject: [PATCH RFC v2 08/10] tools: Add testing support for changes to rcu and slab for sheaves Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250214-slub-percpu-caches-v2-8-88592ee0966a@suse.cz> References: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> In-Reply-To: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> To: Suren Baghdasaryan , "Liam R. Howlett" , Christoph Lameter , David Rientjes Cc: Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Uladzislau Rezki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, maple-tree@lists.infradead.org, "Liam R. Howlett" X-Mailer: b4 0.14.2 X-Spam-Score: -2.80 X-Spamd-Result: default: False [-2.80 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; MIME_TRACE(0.00)[0:+]; TAGGED_RCPT(0.00)[]; TO_DN_SOME(0.00)[]; RCPT_COUNT_TWELVE(0.00)[12]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; FREEMAIL_CC(0.00)[linux.dev,gmail.com,kvack.org,vger.kernel.org,lists.infradead.org,Oracle.com]; R_RATELIMIT(0.00)[to_ip_from(RLtz7ce9b89hw8xzamye9qeynd)]; RCVD_TLS_ALL(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.cz:mid] X-Spam-Flag: NO X-Spam-Level: From: "Liam R. Howlett" Make testing work for the slab and rcu changes that have come in with the sheaves work. This only works with one kmem_cache, and only the first one used. Subsequent setting of keme_cache will not update the active kmem_cache and will be silently dropped because there are other tests which happen after the kmem_cache of interest is set. The saved active kmem_cache is used in the rcu callback, which passes the object to be freed. The rcu call takes the rcu_head, which is passed in as the field in the struct (in this case rcu in the maple tree node), which is calculated by pointer math. The offset of which is saved (in a global variable) for restoring the node pointer on the callback after the rcu grace period expires. Don't use any of this outside of testing, please. Signed-off-by: Liam R. Howlett --- tools/include/linux/slab.h | 41 ++++++++++++++++++++++++++++++++--- tools/testing/shared/linux.c | 24 ++++++++++++++++---- tools/testing/shared/linux/rcupdate.h | 22 +++++++++++++++++++ 3 files changed, 80 insertions(+), 7 deletions(-) diff --git a/tools/include/linux/slab.h b/tools/include/linux/slab.h index 51b25e9c4ec7b66bdf4c68cc1353c6faf1ca7bb8..a475364cfd9fcdb10db252aab18ea3a620326b6b 100644 --- a/tools/include/linux/slab.h +++ b/tools/include/linux/slab.h @@ -22,6 +22,12 @@ enum slab_state { FULL }; +struct kmem_cache_args { + unsigned int align; + unsigned int sheaf_capacity; + void (*ctor)(void *); +}; + static inline void *kzalloc(size_t size, gfp_t gfp) { return kmalloc(size, gfp | __GFP_ZERO); @@ -36,9 +42,38 @@ static inline void *kmem_cache_alloc(struct kmem_cache *cachep, int flags) } void kmem_cache_free(struct kmem_cache *cachep, void *objp); -struct kmem_cache *kmem_cache_create(const char *name, unsigned int size, - unsigned int align, unsigned int flags, - void (*ctor)(void *)); + +struct kmem_cache * +__kmem_cache_create_args(const char *name, unsigned int size, + struct kmem_cache_args *args, unsigned int flags); + +/* If NULL is passed for @args, use this variant with default arguments. */ +static inline struct kmem_cache * +__kmem_cache_default_args(const char *name, unsigned int size, + struct kmem_cache_args *args, unsigned int flags) +{ + struct kmem_cache_args kmem_default_args = {}; + + return __kmem_cache_create_args(name, size, &kmem_default_args, flags); +} + +static inline struct kmem_cache * +__kmem_cache_create(const char *name, unsigned int size, unsigned int align, + unsigned int flags, void (*ctor)(void *)) +{ + struct kmem_cache_args kmem_args = { + .align = align, + .ctor = ctor, + }; + + return __kmem_cache_create_args(name, size, &kmem_args, flags); +} + +#define kmem_cache_create(__name, __object_size, __args, ...) \ + _Generic((__args), \ + struct kmem_cache_args *: __kmem_cache_create_args, \ + void *: __kmem_cache_default_args, \ + default: __kmem_cache_create)(__name, __object_size, __args, __VA_ARGS__) void kmem_cache_free_bulk(struct kmem_cache *cachep, size_t size, void **list); int kmem_cache_alloc_bulk(struct kmem_cache *cachep, gfp_t gfp, size_t size, diff --git a/tools/testing/shared/linux.c b/tools/testing/shared/linux.c index 66dbb362385f3c3d923233448cc591adfe6dc9e7..9f5fd722f27f1d3877be8927be30409cd74ab3c3 100644 --- a/tools/testing/shared/linux.c +++ b/tools/testing/shared/linux.c @@ -20,6 +20,7 @@ struct kmem_cache { pthread_mutex_t lock; unsigned int size; unsigned int align; + unsigned int sheaf_capacity; int nr_objs; void *objs; void (*ctor)(void *); @@ -31,6 +32,8 @@ struct kmem_cache { void *private; }; +static struct kmem_cache *kmem_active = NULL; + void kmem_cache_set_callback(struct kmem_cache *cachep, void (*callback)(void *)) { cachep->callback = callback; @@ -147,6 +150,14 @@ void kmem_cache_free(struct kmem_cache *cachep, void *objp) pthread_mutex_unlock(&cachep->lock); } +void kmem_cache_free_active(void *objp) +{ + if (!kmem_active) + printf("WARNING: No active kmem_cache\n"); + + kmem_cache_free(kmem_active, objp); +} + void kmem_cache_free_bulk(struct kmem_cache *cachep, size_t size, void **list) { if (kmalloc_verbose) @@ -234,23 +245,28 @@ int kmem_cache_alloc_bulk(struct kmem_cache *cachep, gfp_t gfp, size_t size, } struct kmem_cache * -kmem_cache_create(const char *name, unsigned int size, unsigned int align, - unsigned int flags, void (*ctor)(void *)) +__kmem_cache_create_args(const char *name, unsigned int size, + struct kmem_cache_args *args, + unsigned int flags) { struct kmem_cache *ret = malloc(sizeof(*ret)); pthread_mutex_init(&ret->lock, NULL); ret->size = size; - ret->align = align; + ret->align = args->align; + ret->sheaf_capacity = args->sheaf_capacity; ret->nr_objs = 0; ret->nr_allocated = 0; ret->nr_tallocated = 0; ret->objs = NULL; - ret->ctor = ctor; + ret->ctor = args->ctor; ret->non_kernel = 0; ret->exec_callback = false; ret->callback = NULL; ret->private = NULL; + if (!kmem_active) + kmem_active = ret; + return ret; } diff --git a/tools/testing/shared/linux/rcupdate.h b/tools/testing/shared/linux/rcupdate.h index fed468fb0c78db6f33fb1900c7110ab5f3c19c65..c95e2f0bbd93798e544d7d34e0823ed68414f924 100644 --- a/tools/testing/shared/linux/rcupdate.h +++ b/tools/testing/shared/linux/rcupdate.h @@ -9,4 +9,26 @@ #define rcu_dereference_check(p, cond) rcu_dereference(p) #define RCU_INIT_POINTER(p, v) do { (p) = (v); } while (0) +void kmem_cache_free_active(void *objp); +static unsigned long kfree_cb_offset = 0; + +static inline void kfree_rcu_cb(struct rcu_head *head) +{ + void *objp = (void *) ((unsigned long)head - kfree_cb_offset); 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Fri, 14 Feb 2025 16:27:43 +0000 From: Vlastimil Babka Date: Fri, 14 Feb 2025 17:27:45 +0100 Subject: [PATCH RFC v2 09/10] tools: Add sheafs support to testing infrastructure Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250214-slub-percpu-caches-v2-9-88592ee0966a@suse.cz> References: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> In-Reply-To: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> To: Suren Baghdasaryan , "Liam R. Howlett" , Christoph Lameter , David Rientjes Cc: Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Uladzislau Rezki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, maple-tree@lists.infradead.org, "Liam R. Howlett" X-Mailer: b4 0.14.2 X-Spam-Level: X-Spamd-Result: default: False [-2.80 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; MIME_TRACE(0.00)[0:+]; TAGGED_RCPT(0.00)[]; TO_DN_SOME(0.00)[]; RCPT_COUNT_TWELVE(0.00)[12]; RCVD_TLS_ALL(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[linux.dev,gmail.com,kvack.org,vger.kernel.org,lists.infradead.org,Oracle.com]; R_RATELIMIT(0.00)[to_ip_from(RLtz7ce9b89hw8xzamye9qeynd)]; FROM_EQ_ENVFROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.cz:mid] X-Spam-Score: -2.80 X-Spam-Flag: NO From: "Liam R. Howlett" Allocate a sheaf and fill it to the count amount. Does not fill to the sheaf limit to detect incorrect allocation requests. Signed-off-by: Liam R. Howlett --- tools/include/linux/slab.h | 24 +++++++++++++ tools/testing/shared/linux.c | 84 ++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 108 insertions(+) diff --git a/tools/include/linux/slab.h b/tools/include/linux/slab.h index a475364cfd9fcdb10db252aab18ea3a620326b6b..0b6b42c9921fc402b4f3d4f681a95c9067d128db 100644 --- a/tools/include/linux/slab.h +++ b/tools/include/linux/slab.h @@ -22,6 +22,13 @@ enum slab_state { FULL }; +struct slab_sheaf { + struct kmem_cache *cache; + unsigned int size; + unsigned int capacity; + void *objects[]; +}; + struct kmem_cache_args { unsigned int align; unsigned int sheaf_capacity; @@ -79,4 +86,21 @@ void kmem_cache_free_bulk(struct kmem_cache *cachep, size_t size, void **list); int kmem_cache_alloc_bulk(struct kmem_cache *cachep, gfp_t gfp, size_t size, void **list); +struct slab_sheaf * +kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size); + +void * +kmem_cache_alloc_from_sheaf(struct kmem_cache *s, gfp_t gfp, + struct slab_sheaf *sheaf); + +void kmem_cache_return_sheaf(struct kmem_cache *s, gfp_t gfp, + struct slab_sheaf *sheaf); +int kmem_cache_refill_sheaf(struct kmem_cache *s, gfp_t gfp, + struct slab_sheaf **sheafp, unsigned int size); + +static inline unsigned int kmem_cache_sheaf_size(struct slab_sheaf *sheaf) +{ + return sheaf->size; +} + #endif /* _TOOLS_SLAB_H */ diff --git a/tools/testing/shared/linux.c b/tools/testing/shared/linux.c index 9f5fd722f27f1d3877be8927be30409cd74ab3c3..a61c755c3c87e80036a5173115e955bfe7d5a80c 100644 --- a/tools/testing/shared/linux.c +++ b/tools/testing/shared/linux.c @@ -181,6 +181,12 @@ int kmem_cache_alloc_bulk(struct kmem_cache *cachep, gfp_t gfp, size_t size, if (kmalloc_verbose) pr_debug("Bulk alloc %lu\n", size); + if (cachep->exec_callback) { + if (cachep->callback) + cachep->callback(cachep->private); + cachep->exec_callback = false; + } + pthread_mutex_lock(&cachep->lock); if (cachep->nr_objs >= size) { struct radix_tree_node *node; @@ -270,6 +276,84 @@ __kmem_cache_create_args(const char *name, unsigned int size, return ret; } +struct slab_sheaf * +kmem_cache_prefill_sheaf(struct kmem_cache *s, gfp_t gfp, unsigned int size) +{ + struct slab_sheaf *sheaf; + unsigned int capacity; + + if (size > s->sheaf_capacity) + capacity = size; + else + capacity = s->sheaf_capacity; + + sheaf = malloc(sizeof(*sheaf) + sizeof(void *) * s->sheaf_capacity * capacity); + if (!sheaf) { + return NULL; + } + + memset(sheaf, 0, size); + sheaf->cache = s; + sheaf->capacity = capacity; + sheaf->size = kmem_cache_alloc_bulk(s, gfp, size, sheaf->objects); + if (!sheaf->size) { + free(sheaf); + return NULL; + } + + return sheaf; +} + +int kmem_cache_refill_sheaf(struct kmem_cache *s, gfp_t gfp, + struct slab_sheaf **sheafp, unsigned int size) +{ + struct slab_sheaf *sheaf = *sheafp; + int refill; + + if (sheaf->size >= size) + return 0; + + if (size > sheaf->capacity) { + sheaf = kmem_cache_prefill_sheaf(s, gfp, size); + if (!sheaf) + return -ENOMEM; + + kmem_cache_return_sheaf(s, gfp, *sheafp); + *sheafp = sheaf; + return 0; + } + + refill = kmem_cache_alloc_bulk(s, gfp, size - sheaf->size, + &sheaf->objects[sheaf->size]); + if (!refill) + return -ENOMEM; + + sheaf->size += refill; + return 0; +} + +void kmem_cache_return_sheaf(struct kmem_cache *s, gfp_t gfp, + struct slab_sheaf *sheaf) +{ + if (sheaf->size) { + //s->non_kernel += sheaf->size; + kmem_cache_free_bulk(s, sheaf->size, &sheaf->objects[0]); + } + free(sheaf); +} + +void * +kmem_cache_alloc_from_sheaf(struct kmem_cache *s, gfp_t gfp, + struct slab_sheaf *sheaf) +{ + if (sheaf->size == 0) { + printf("Nothing left in sheaf!\n"); + return NULL; + } + + return sheaf->objects[--sheaf->size]; +} + /* * Test the test infrastructure for kem_cache_alloc/free and bulk counterparts. */ From patchwork Fri Feb 14 16:27:46 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Vlastimil Babka X-Patchwork-Id: 13975242 Received: from smtp-out1.suse.de (smtp-out1.suse.de [195.135.223.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 4CBCE2686BD for ; 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Fri, 14 Feb 2025 16:27:43 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id cC/MB/9ur2eHSAAAD6G6ig (envelope-from ); Fri, 14 Feb 2025 16:27:43 +0000 From: Vlastimil Babka Date: Fri, 14 Feb 2025 17:27:46 +0100 Subject: [PATCH RFC v2 10/10] maple_tree: use percpu sheaves for maple_node_cache Precedence: bulk X-Mailing-List: rcu@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Message-Id: <20250214-slub-percpu-caches-v2-10-88592ee0966a@suse.cz> References: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> In-Reply-To: <20250214-slub-percpu-caches-v2-0-88592ee0966a@suse.cz> To: Suren Baghdasaryan , "Liam R. Howlett" , Christoph Lameter , David Rientjes Cc: Roman Gushchin , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Uladzislau Rezki , linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcu@vger.kernel.org, maple-tree@lists.infradead.org, Vlastimil Babka X-Mailer: b4 0.14.2 X-Spam-Level: X-Spamd-Result: default: False [-6.80 / 50.00]; REPLY(-4.00)[]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; TAGGED_RCPT(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; MIME_TRACE(0.00)[0:+]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; RCPT_COUNT_TWELVE(0.00)[12]; RCVD_TLS_ALL(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[linux.dev,gmail.com,kvack.org,vger.kernel.org,lists.infradead.org,suse.cz]; R_RATELIMIT(0.00)[to_ip_from(RLtz7ce9b89hw8xzamye9qeynd)]; FROM_EQ_ENVFROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.cz:email,suse.cz:mid] X-Spam-Score: -6.80 X-Spam-Flag: NO Setup the maple_node_cache with percpu sheaves of size 32 to hopefully improve its performance. Change the single node rcu freeing in ma_free_rcu() to use kfree_rcu() instead of the custom callback, which allows the rcu_free sheaf batching to be used. Note there are other users of mt_free_rcu() where larger parts of maple tree are submitted to call_rcu() as a whole, and that cannot use the rcu_free sheaf, but it's still possible for maple nodes freed this way to be reused via the barn, even if only some cpus are allowed to process rcu callbacks. Signed-off-by: Vlastimil Babka --- lib/maple_tree.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) diff --git a/lib/maple_tree.c b/lib/maple_tree.c index f7153ade1be5f16423f0ca073846a7f3dfa60523..56e7a00f6f0941bff163091c999a873e4273f071 100644 --- a/lib/maple_tree.c +++ b/lib/maple_tree.c @@ -208,7 +208,7 @@ static void mt_free_rcu(struct rcu_head *head) static void ma_free_rcu(struct maple_node *node) { WARN_ON(node->parent != ma_parent_ptr(node)); - call_rcu(&node->rcu, mt_free_rcu); + kfree_rcu(node, rcu); } static void mas_set_height(struct ma_state *mas) @@ -6258,9 +6258,14 @@ bool mas_nomem(struct ma_state *mas, gfp_t gfp) void __init maple_tree_init(void) { + struct kmem_cache_args args = { + .align = sizeof(struct maple_node), + .sheaf_capacity = 32, + }; + maple_node_cache = kmem_cache_create("maple_node", - sizeof(struct maple_node), sizeof(struct maple_node), - SLAB_PANIC, NULL); + sizeof(struct maple_node), &args, + SLAB_PANIC); } /**