// SPDX-License-Identifier: GPL-2.0 /* * linux/mm/slab.c * Written by Mark Hemment, 1996/97. * (markhe@nextd.demon.co.uk) * * kmem_cache_destroy() + some cleanup - 1999 Andrea Arcangeli * * Major cleanup, different bufctl logic, per-cpu arrays * (c) 2000 Manfred Spraul * * Cleanup, make the head arrays unconditional, preparation for NUMA * (c) 2002 Manfred Spraul * * An implementation of the Slab Allocator as described in outline in; * UNIX Internals: The New Frontiers by Uresh Vahalia * Pub: Prentice Hall ISBN 0-13-101908-2 * or with a little more detail in; * The Slab Allocator: An Object-Caching Kernel Memory Allocator * Jeff Bonwick (Sun Microsystems). * Presented at: USENIX Summer 1994 Technical Conference * * The memory is organized in caches, one cache for each object type. * (e.g. inode_cache, dentry_cache, buffer_head, vm_area_struct) * Each cache consists out of many slabs (they are small (usually one * page long) and always contiguous), and each slab contains multiple * initialized objects. * * This means, that your constructor is used only for newly allocated * slabs and you must pass objects with the same initializations to * kmem_cache_free. * * Each cache can only support one memory type (GFP_DMA, GFP_HIGHMEM, * normal). If you need a special memory type, then must create a new * cache for that memory type. * * In order to reduce fragmentation, the slabs are sorted in 3 groups: * full slabs with 0 free objects * partial slabs * empty slabs with no allocated objects * * If partial slabs exist, then new allocations come from these slabs, * otherwise from empty slabs or new slabs are allocated. * * kmem_cache_destroy() CAN CRASH if you try to allocate from the cache * during kmem_cache_destroy(). The caller must prevent concurrent allocs. * * Each cache has a short per-cpu head array, most allocs * and frees go into that array, and if that array overflows, then 1/2 * of the entries in the array are given back into the global cache. * The head array is strictly LIFO and should improve the cache hit rates. * On SMP, it additionally reduces the spinlock operations. * * The c_cpuarray may not be read with enabled local interrupts - * it's changed with a smp_call_function(). * * SMP synchronization: * constructors and destructors are called without any locking. * Several members in struct kmem_cache and struct slab never change, they * are accessed without any locking. * The per-cpu arrays are never accessed from the wrong cpu, no locking, * and local interrupts are disabled so slab code is preempt-safe. * The non-constant members are protected with a per-cache irq spinlock. * * Many thanks to Mark Hemment, who wrote another per-cpu slab patch * in 2000 - many ideas in the current implementation are derived from * his patch. * * Further notes from the original documentation: * * 11 April '97. Started multi-threading - markhe * The global cache-chain is protected by the mutex 'slab_mutex'. * The sem is only needed when accessing/extending the cache-chain, which * can never happen inside an interrupt (kmem_cache_create(), * kmem_cache_shrink() and kmem_cache_reap()). * * At present, each engine can be growing a cache. This should be blocked. * * 15 March 2005. NUMA slab allocator. * Shai Fultheim . * Shobhit Dayal * Alok N Kataria * Christoph Lameter * * Modified the slab allocator to be node aware on NUMA systems. * Each node has its own list of partial, free and full slabs. * All object allocations for a node occur from node specific slab lists. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "internal.h" #include "slab.h" /* * DEBUG - 1 for kmem_cache_create() to honour; SLAB_RED_ZONE & SLAB_POISON. * 0 for faster, smaller code (especially in the critical paths). * * STATS - 1 to collect stats for /proc/slabinfo. * 0 for faster, smaller code (especially in the critical paths). * * FORCED_DEBUG - 1 enables SLAB_RED_ZONE and SLAB_POISON (if possible) */ #ifdef CONFIG_DEBUG_SLAB #define DEBUG 1 #define STATS 1 #define FORCED_DEBUG 1 #else #define DEBUG 0 #define STATS 0 #define FORCED_DEBUG 0 #endif /* Shouldn't this be in a header file somewhere? */ #define BYTES_PER_WORD sizeof(void *) #define REDZONE_ALIGN max(BYTES_PER_WORD, __alignof__(unsigned long long)) #ifndef ARCH_KMALLOC_FLAGS #define ARCH_KMALLOC_FLAGS SLAB_HWCACHE_ALIGN #endif #define FREELIST_BYTE_INDEX (((PAGE_SIZE >> BITS_PER_BYTE) \ <= SLAB_OBJ_MIN_SIZE) ? 1 : 0) #if FREELIST_BYTE_INDEX typedef unsigned char freelist_idx_t; #else typedef unsigned short freelist_idx_t; #endif #define SLAB_OBJ_MAX_NUM ((1 << sizeof(freelist_idx_t) * BITS_PER_BYTE) - 1) /* * struct array_cache * * Purpose: * - LIFO ordering, to hand out cache-warm objects from _alloc * - reduce the number of linked list operations * - reduce spinlock operations * * The limit is stored in the per-cpu structure to reduce the data cache * footprint. * */ struct array_cache { unsigned int avail; unsigned int limit; unsigned int batchcount; unsigned int touched; void *entry[]; /* * Must have this definition in here for the proper * alignment of array_cache. Also simplifies accessing * the entries. */ }; struct alien_cache { spinlock_t lock; struct array_cache ac; }; /* * Need this for bootstrapping a per node allocator. */ #define NUM_INIT_LISTS (2 * MAX_NUMNODES) static struct kmem_cache_node __initdata init_kmem_cache_node[NUM_INIT_LISTS]; #define CACHE_CACHE 0 #define SIZE_NODE (MAX_NUMNODES) static int drain_freelist(struct kmem_cache *cache, struct kmem_cache_node *n, int tofree); static void free_block(struct kmem_cache *cachep, void **objpp, int len, int node, struct list_head *list); static void slabs_destroy(struct kmem_cache *cachep, struct list_head *list); static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp); static void cache_reap(struct work_struct *unused); static inline void fixup_objfreelist_debug(struct kmem_cache *cachep, void **list); static inline void fixup_slab_list(struct kmem_cache *cachep, struct kmem_cache_node *n, struct slab *slab, void **list); static int slab_early_init = 1; #define INDEX_NODE kmalloc_index(sizeof(struct kmem_cache_node)) static void kmem_cache_node_init(struct kmem_cache_node *parent) { INIT_LIST_HEAD(&parent->slabs_full); INIT_LIST_HEAD(&parent->slabs_partial); INIT_LIST_HEAD(&parent->slabs_free); parent->total_slabs = 0; parent->free_slabs = 0; parent->shared = NULL; parent->alien = NULL; parent->colour_next = 0; spin_lock_init(&parent->list_lock); parent->free_objects = 0; parent->free_touched = 0; } #define MAKE_LIST(cachep, listp, slab, nodeid) \ do { \ INIT_LIST_HEAD(listp); \ list_splice(&get_node(cachep, nodeid)->slab, listp); \ } while (0) #define MAKE_ALL_LISTS(cachep, ptr, nodeid) \ do { \ MAKE_LIST((cachep), (&(ptr)->slabs_full), slabs_full, nodeid); \ MAKE_LIST((cachep), (&(ptr)->slabs_partial), slabs_partial, nodeid); \ MAKE_LIST((cachep), (&(ptr)->slabs_free), slabs_free, nodeid); \ } while (0) #define CFLGS_OBJFREELIST_SLAB ((slab_flags_t __force)0x40000000U) #define CFLGS_OFF_SLAB ((slab_flags_t __force)0x80000000U) #define OBJFREELIST_SLAB(x) ((x)->flags & CFLGS_OBJFREELIST_SLAB) #define OFF_SLAB(x) ((x)->flags & CFLGS_OFF_SLAB) #define BATCHREFILL_LIMIT 16 /* * Optimization question: fewer reaps means less probability for unnecessary * cpucache drain/refill cycles. * * OTOH the cpuarrays can contain lots of objects, * which could lock up otherwise freeable slabs. */ #define REAPTIMEOUT_AC (2*HZ) #define REAPTIMEOUT_NODE (4*HZ) #if STATS #define STATS_INC_ACTIVE(x) ((x)->num_active++) #define STATS_DEC_ACTIVE(x) ((x)->num_active--) #define STATS_INC_ALLOCED(x) ((x)->num_allocations++) #define STATS_INC_GROWN(x) ((x)->grown++) #define STATS_ADD_REAPED(x, y) ((x)->reaped += (y)) #define STATS_SET_HIGH(x) \ do { \ if ((x)->num_active > (x)->high_mark) \ (x)->high_mark = (x)->num_active; \ } while (0) #define STATS_INC_ERR(x) ((x)->errors++) #define STATS_INC_NODEALLOCS(x) ((x)->node_allocs++) #define STATS_INC_NODEFREES(x) ((x)->node_frees++) #define STATS_INC_ACOVERFLOW(x) ((x)->node_overflow++) #define STATS_SET_FREEABLE(x, i) \ do { \ if ((x)->max_freeable < i) \ (x)->max_freeable = i; \ } while (0) #define STATS_INC_ALLOCHIT(x) atomic_inc(&(x)->allochit) #define STATS_INC_ALLOCMISS(x) atomic_inc(&(x)->allocmiss) #define STATS_INC_FREEHIT(x) atomic_inc(&(x)->freehit) #define STATS_INC_FREEMISS(x) atomic_inc(&(x)->freemiss) #else #define STATS_INC_ACTIVE(x) do { } while (0) #define STATS_DEC_ACTIVE(x) do { } while (0) #define STATS_INC_ALLOCED(x) do { } while (0) #define STATS_INC_GROWN(x) do { } while (0) #define STATS_ADD_REAPED(x, y) do { (void)(y); } while (0) #define STATS_SET_HIGH(x) do { } while (0) #define STATS_INC_ERR(x) do { } while (0) #define STATS_INC_NODEALLOCS(x) do { } while (0) #define STATS_INC_NODEFREES(x) do { } while (0) #define STATS_INC_ACOVERFLOW(x) do { } while (0) #define STATS_SET_FREEABLE(x, i) do { } while (0) #define STATS_INC_ALLOCHIT(x) do { } while (0) #define STATS_INC_ALLOCMISS(x) do { } while (0) #define STATS_INC_FREEHIT(x) do { } while (0) #define STATS_INC_FREEMISS(x) do { } while (0) #endif #if DEBUG /* * memory layout of objects: * 0 : objp * 0 .. cachep->obj_offset - BYTES_PER_WORD - 1: padding. This ensures that * the end of an object is aligned with the end of the real * allocation. Catches writes behind the end of the allocation. * cachep->obj_offset - BYTES_PER_WORD .. cachep->obj_offset - 1: * redzone word. * cachep->obj_offset: The real object. * cachep->size - 2* BYTES_PER_WORD: redzone word [BYTES_PER_WORD long] * cachep->size - 1* BYTES_PER_WORD: last caller address * [BYTES_PER_WORD long] */ static int obj_offset(struct kmem_cache *cachep) { return cachep->obj_offset; } static unsigned long long *dbg_redzone1(struct kmem_cache *cachep, void *objp) { BUG_ON(!(cachep->flags & SLAB_RED_ZONE)); return (unsigned long long *) (objp + obj_offset(cachep) - sizeof(unsigned long long)); } static unsigned long long *dbg_redzone2(struct kmem_cache *cachep, void *objp) { BUG_ON(!(cachep->flags & SLAB_RED_ZONE)); if (cachep->flags & SLAB_STORE_USER) return (unsigned long long *)(objp + cachep->size - sizeof(unsigned long long) - REDZONE_ALIGN); return (unsigned long long *) (objp + cachep->size - sizeof(unsigned long long)); } static void **dbg_userword(struct kmem_cache *cachep, void *objp) { BUG_ON(!(cachep->flags & SLAB_STORE_USER)); return (void **)(objp + cachep->size - BYTES_PER_WORD); } #else #define obj_offset(x) 0 #define dbg_redzone1(cachep, objp) ({BUG(); (unsigned long long *)NULL;}) #define dbg_redzone2(cachep, objp) ({BUG(); (unsigned long long *)NULL;}) #define dbg_userword(cachep, objp) ({BUG(); (void **)NULL;}) #endif /* * Do not go above this order unless 0 objects fit into the slab or * overridden on the command line. */ #define SLAB_MAX_ORDER_HI 1 #define SLAB_MAX_ORDER_LO 0 static int slab_max_order = SLAB_MAX_ORDER_LO; static bool slab_max_order_set __initdata; static inline void *index_to_obj(struct kmem_cache *cache, const struct slab *slab, unsigned int idx) { return slab->s_mem + cache->size * idx; } #define BOOT_CPUCACHE_ENTRIES 1 /* internal cache of cache description objs */ static struct kmem_cache kmem_cache_boot = { .batchcount = 1, .limit = BOOT_CPUCACHE_ENTRIES, .shared = 1, .size = sizeof(struct kmem_cache), .name = "kmem_cache", }; static DEFINE_PER_CPU(struct delayed_work, slab_reap_work); static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep) { return this_cpu_ptr(cachep->cpu_cache); } /* * Calculate the number of objects and left-over bytes for a given buffer size. */ static unsigned int cache_estimate(unsigned long gfporder, size_t buffer_size, slab_flags_t flags, size_t *left_over) { unsigned int num; size_t slab_size = PAGE_SIZE << gfporder; /* * The slab management structure can be either off the slab or * on it. For the latter case, the memory allocated for a * slab is used for: * * - @buffer_size bytes for each object * - One freelist_idx_t for each object * * We don't need to consider alignment of freelist because * freelist will be at the end of slab page. The objects will be * at the correct alignment. * * If the slab management structure is off the slab, then the * alignment will already be calculated into the size. Because * the slabs are all pages aligned, the objects will be at the * correct alignment when allocated. */ if (flags & (CFLGS_OBJFREELIST_SLAB | CFLGS_OFF_SLAB)) { num = slab_size / buffer_size; *left_over = slab_size % buffer_size; } else { num = slab_size / (buffer_size + sizeof(freelist_idx_t)); *left_over = slab_size % (buffer_size + sizeof(freelist_idx_t)); } return num; } #if DEBUG #define slab_error(cachep, msg) __slab_error(__func__, cachep, msg) static void __slab_error(const char *function, struct kmem_cache *cachep, char *msg) { pr_err("slab error in %s(): cache `%s': %s\n", function, cachep->name, msg); dump_stack(); add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); } #endif /* * By default on NUMA we use alien caches to stage the freeing of * objects allocated from other nodes. This causes massive memory * inefficiencies when using fake NUMA setup to split memory into a * large number of small nodes, so it can be disabled on the command * line */ static int use_alien_caches __read_mostly = 1; static int __init noaliencache_setup(char *s) { use_alien_caches = 0; return 1; } __setup("noaliencache", noaliencache_setup); static int __init slab_max_order_setup(char *str) { get_option(&str, &slab_max_order); slab_max_order = slab_max_order < 0 ? 0 : min(slab_max_order, MAX_ORDER - 1); slab_max_order_set = true; return 1; } __setup("slab_max_order=", slab_max_order_setup); #ifdef CONFIG_NUMA /* * Special reaping functions for NUMA systems called from cache_reap(). * These take care of doing round robin flushing of alien caches (containing * objects freed on different nodes from which they were allocated) and the * flushing of remote pcps by calling drain_node_pages. */ static DEFINE_PER_CPU(unsigned long, slab_reap_node); static void init_reap_node(int cpu) { per_cpu(slab_reap_node, cpu) = next_node_in(cpu_to_mem(cpu), node_online_map); } static void next_reap_node(void) { int node = __this_cpu_read(slab_reap_node); node = next_node_in(node, node_online_map); __this_cpu_write(slab_reap_node, node); } #else #define init_reap_node(cpu) do { } while (0) #define next_reap_node(void) do { } while (0) #endif /* * Initiate the reap timer running on the target CPU. We run at around 1 to 2Hz * via the workqueue/eventd. * Add the CPU number into the expiration time to minimize the possibility of * the CPUs getting into lockstep and contending for the global cache chain * lock. */ static void start_cpu_timer(int cpu) { struct delayed_work *reap_work = &per_cpu(slab_reap_work, cpu); if (reap_work->work.func == NULL) { init_reap_node(cpu); INIT_DEFERRABLE_WORK(reap_work, cache_reap); schedule_delayed_work_on(cpu, reap_work, __round_jiffies_relative(HZ, cpu)); } } static void init_arraycache(struct array_cache *ac, int limit, int batch) { if (ac) { ac->avail = 0; ac->limit = limit; ac->batchcount = batch; ac->touched = 0; } } static struct array_cache *alloc_arraycache(int node, int entries, int batchcount, gfp_t gfp) { size_t memsize = sizeof(void *) * entries + sizeof(struct array_cache); struct array_cache *ac = NULL; ac = kmalloc_node(memsize, gfp, node); /* * The array_cache structures contain pointers to free object. * However, when such objects are allocated or transferred to another * cache the pointers are not cleared and they could be counted as * valid references during a kmemleak scan. Therefore, kmemleak must * not scan such objects. */ kmemleak_no_scan(ac); init_arraycache(ac, entries, batchcount); return ac; } static noinline void cache_free_pfmemalloc(struct kmem_cache *cachep, struct slab *slab, void *objp) { struct kmem_cache_node *n; int slab_node; LIST_HEAD(list); slab_node = slab_nid(slab); n = get_node(cachep, slab_node); spin_lock(&n->list_lock); free_block(cachep, &objp, 1, slab_node, &list); spin_unlock(&n->list_lock); slabs_destroy(cachep, &list); } /* * Transfer objects in one arraycache to another. * Locking must be handled by the caller. * * Return the number of entries transferred. */ static int transfer_objects(struct array_cache *to, struct array_cache *from, unsigned int max) { /* Figure out how many entries to transfer */ int nr = min3(from->avail, max, to->limit - to->avail); if (!nr) return 0; memcpy(to->entry + to->avail, from->entry + from->avail - nr, sizeof(void *) *nr); from->avail -= nr; to->avail += nr; return nr; } /* &alien->lock must be held by alien callers. */ static __always_inline void __free_one(struct array_cache *ac, void *objp) { /* Avoid trivial double-free. */ if (IS_ENABLED(CONFIG_SLAB_FREELIST_HARDENED) && WARN_ON_ONCE(ac->avail > 0 && ac->entry[ac->avail - 1] == objp)) return; ac->entry[ac->avail++] = objp; } #ifndef CONFIG_NUMA #define drain_alien_cache(cachep, alien) do { } while (0) #define reap_alien(cachep, n) do { } while (0) static inline struct alien_cache **alloc_alien_cache(int node, int limit, gfp_t gfp) { return NULL; } static inline void free_alien_cache(struct alien_cache **ac_ptr) { } static inline int cache_free_alien(struct kmem_cache *cachep, void *objp) { return 0; } static inline gfp_t gfp_exact_node(gfp_t flags) { return flags & ~__GFP_NOFAIL; } #else /* CONFIG_NUMA */ static struct alien_cache *__alloc_alien_cache(int node, int entries, int batch, gfp_t gfp) { size_t memsize = sizeof(void *) * entries + sizeof(struct alien_cache); struct alien_cache *alc = NULL; alc = kmalloc_node(memsize, gfp, node); if (alc) { kmemleak_no_scan(alc); init_arraycache(&alc->ac, entries, batch); spin_lock_init(&alc->lock); } return alc; } static struct alien_cache **alloc_alien_cache(int node, int limit, gfp_t gfp) { struct alien_cache **alc_ptr; int i; if (limit > 1) limit = 12; alc_ptr = kcalloc_node(nr_node_ids, sizeof(void *), gfp, node); if (!alc_ptr) return NULL; for_each_node(i) { if (i == node || !node_online(i)) continue; alc_ptr[i] = __alloc_alien_cache(node, limit, 0xbaadf00d, gfp); if (!alc_ptr[i]) { for (i--; i >= 0; i--) kfree(alc_ptr[i]); kfree(alc_ptr); return NULL; } } return alc_ptr; } static void free_alien_cache(struct alien_cache **alc_ptr) { int i; if (!alc_ptr) return; for_each_node(i) kfree(alc_ptr[i]); kfree(alc_ptr); } static void __drain_alien_cache(struct kmem_cache *cachep, struct array_cache *ac, int node, struct list_head *list) { struct kmem_cache_node *n = get_node(cachep, node); if (ac->avail) { spin_lock(&n->list_lock); /* * Stuff objects into the remote nodes shared array first. * That way we could avoid the overhead of putting the objects * into the free lists and getting them back later. */ if (n->shared) transfer_objects(n->shared, ac, ac->limit); free_block(cachep, ac->entry, ac->avail, node, list); ac->avail = 0; spin_unlock(&n->list_lock); } } /* * Called from cache_reap() to regularly drain alien caches round robin. */ static void reap_alien(struct kmem_cache *cachep, struct kmem_cache_node *n) { int node = __this_cpu_read(slab_reap_node); if (n->alien) { struct alien_cache *alc = n->alien[node]; struct array_cache *ac; if (alc) { ac = &alc->ac; if (ac->avail && spin_trylock_irq(&alc->lock)) { LIST_HEAD(list); __drain_alien_cache(cachep, ac, node, &list); spin_unlock_irq(&alc->lock); slabs_destroy(cachep, &list); } } } } static void drain_alien_cache(struct kmem_cache *cachep, struct alien_cache **alien) { int i = 0; struct alien_cache *alc; struct array_cache *ac; unsigned long flags; for_each_online_node(i) { alc = alien[i]; if (alc) { LIST_HEAD(list); ac = &alc->ac; spin_lock_irqsave(&alc->lock, flags); __drain_alien_cache(cachep, ac, i, &list); spin_unlock_irqrestore(&alc->lock, flags); slabs_destroy(cachep, &list); } } } static int __cache_free_alien(struct kmem_cache *cachep, void *objp, int node, int slab_node) { struct kmem_cache_node *n; struct alien_cache *alien = NULL; struct array_cache *ac; LIST_HEAD(list); n = get_node(cachep, node); STATS_INC_NODEFREES(cachep); if (n->alien && n->alien[slab_node]) { alien = n->alien[slab_node]; ac = &alien->ac; spin_lock(&alien->lock); if (unlikely(ac->avail == ac->limit)) { STATS_INC_ACOVERFLOW(cachep); __drain_alien_cache(cachep, ac, slab_node, &list); } __free_one(ac, objp); spin_unlock(&alien->lock); slabs_destroy(cachep, &list); } else { n = get_node(cachep, slab_node); spin_lock(&n->list_lock); free_block(cachep, &objp, 1, slab_node, &list); spin_unlock(&n->list_lock); slabs_destroy(cachep, &list); } return 1; } static inline int cache_free_alien(struct kmem_cache *cachep, void *objp) { int slab_node = slab_nid(virt_to_slab(objp)); int node = numa_mem_id(); /* * Make sure we are not freeing an object from another node to the array * cache on this cpu. */ if (likely(node == slab_node)) return 0; return __cache_free_alien(cachep, objp, node, slab_node); } /* * Construct gfp mask to allocate from a specific node but do not reclaim or * warn about failures. */ static inline gfp_t gfp_exact_node(gfp_t flags) { return (flags | __GFP_THISNODE | __GFP_NOWARN) & ~(__GFP_RECLAIM|__GFP_NOFAIL); } #endif static int init_cache_node(struct kmem_cache *cachep, int node, gfp_t gfp) { struct kmem_cache_node *n; /* * Set up the kmem_cache_node for cpu before we can * begin anything. Make sure some other cpu on this * node has not already allocated this */ n = get_node(cachep, node); if (n) { spin_lock_irq(&n->list_lock); n->free_limit = (1 + nr_cpus_node(node)) * cachep->batchcount + cachep->num; spin_unlock_irq(&n->list_lock); return 0; } n = kmalloc_node(sizeof(struct kmem_cache_node), gfp, node); if (!n) return -ENOMEM; kmem_cache_node_init(n); n->next_reap = jiffies + REAPTIMEOUT_NODE + ((unsigned long)cachep) % REAPTIMEOUT_NODE; n->free_limit = (1 + nr_cpus_node(node)) * cachep->batchcount + cachep->num; /* * The kmem_cache_nodes don't come and go as CPUs * come and go. slab_mutex provides sufficient * protection here. */ cachep->node[node] = n; return 0; } #if (defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG)) || defined(CONFIG_SMP) /* * Allocates and initializes node for a node on each slab cache, used for * either memory or cpu hotplug. If memory is being hot-added, the kmem_cache_node * will be allocated off-node since memory is not yet online for the new node. * When hotplugging memory or a cpu, existing nodes are not replaced if * already in use. * * Must hold slab_mutex. */ static int init_cache_node_node(int node) { int ret; struct kmem_cache *cachep; list_for_each_entry(cachep, &slab_caches, list) { ret = init_cache_node(cachep, node, GFP_KERNEL); if (ret) return ret; } return 0; } #endif static int setup_kmem_cache_node(struct kmem_cache *cachep, int node, gfp_t gfp, bool force_change) { int ret = -ENOMEM; struct kmem_cache_node *n; struct array_cache *old_shared = NULL; struct array_cache *new_shared = NULL; struct alien_cache **new_alien = NULL; LIST_HEAD(list); if (use_alien_caches) { new_alien = alloc_alien_cache(node, cachep->limit, gfp); if (!new_alien) goto fail; } if (cachep->shared) { new_shared = alloc_arraycache(node, cachep->shared * cachep->batchcount, 0xbaadf00d, gfp); if (!new_shared) goto fail; } ret = init_cache_node(cachep, node, gfp); if (ret) goto fail; n = get_node(cachep, node); spin_lock_irq(&n->list_lock); if (n->shared && force_change) { free_block(cachep, n->shared->entry, n->shared->avail, node, &list); n->shared->avail = 0; } if (!n->shared || force_change) { old_shared = n->shared; n->shared = new_shared; new_shared = NULL; } if (!n->alien) { n->alien = new_alien; new_alien = NULL; } spin_unlock_irq(&n->list_lock); slabs_destroy(cachep, &list); /* * To protect lockless access to n->shared during irq disabled context. * If n->shared isn't NULL in irq disabled context, accessing to it is * guaranteed to be valid until irq is re-enabled, because it will be * freed after synchronize_rcu(). */ if (old_shared && force_change) synchronize_rcu(); fail: kfree(old_shared); kfree(new_shared); free_alien_cache(new_alien); return ret; } #ifdef CONFIG_SMP static void cpuup_canceled(long cpu) { struct kmem_cache *cachep; struct kmem_cache_node *n = NULL; int node = cpu_to_mem(cpu); const struct cpumask *mask = cpumask_of_node(node); list_for_each_entry(cachep, &slab_caches, list) { struct array_cache *nc; struct array_cache *shared; struct alien_cache **alien; LIST_HEAD(list); n = get_node(cachep, node); if (!n) continue; spin_lock_irq(&n->list_lock); /* Free limit for this kmem_cache_node */ n->free_limit -= cachep->batchcount; /* cpu is dead; no one can alloc from it. */ nc = per_cpu_ptr(cachep->cpu_cache, cpu); free_block(cachep, nc->entry, nc->avail, node, &list); nc->avail = 0; if (!cpumask_empty(mask)) { spin_unlock_irq(&n->list_lock); goto free_slab; } shared = n->shared; if (shared) { free_block(cachep, shared->entry, shared->avail, node, &list); n->shared = NULL; } alien = n->alien; n->alien = NULL; spin_unlock_irq(&n->list_lock); kfree(shared); if (alien) { drain_alien_cache(cachep, alien); free_alien_cache(alien); } free_slab: slabs_destroy(cachep, &list); } /* * In the previous loop, all the objects were freed to * the respective cache's slabs, now we can go ahead and * shrink each nodelist to its limit. */ list_for_each_entry(cachep, &slab_caches, list) { n = get_node(cachep, node); if (!n) continue; drain_freelist(cachep, n, INT_MAX); } } static int cpuup_prepare(long cpu) { struct kmem_cache *cachep; int node = cpu_to_mem(cpu); int err; /* * We need to do this right in the beginning since * alloc_arraycache's are going to use this list. * kmalloc_node allows us to add the slab to the right * kmem_cache_node and not this cpu's kmem_cache_node */ err = init_cache_node_node(node); if (err < 0) goto bad; /* * Now we can go ahead with allocating the shared arrays and * array caches */ list_for_each_entry(cachep, &slab_caches, list) { err = setup_kmem_cache_node(cachep, node, GFP_KERNEL, false); if (err) goto bad; } return 0; bad: cpuup_canceled(cpu); return -ENOMEM; } int slab_prepare_cpu(unsigned int cpu) { int err; mutex_lock(&slab_mutex); err = cpuup_prepare(cpu); mutex_unlock(&slab_mutex); return err; } /* * This is called for a failed online attempt and for a successful * offline. * * Even if all the cpus of a node are down, we don't free the * kmem_cache_node of any cache. This is to avoid a race between cpu_down, and * a kmalloc allocation from another cpu for memory from the node of * the cpu going down. The kmem_cache_node structure is usually allocated from * kmem_cache_create() and gets destroyed at kmem_cache_destroy(). */ int slab_dead_cpu(unsigned int cpu) { mutex_lock(&slab_mutex); cpuup_canceled(cpu); mutex_unlock(&slab_mutex); return 0; } #endif static int slab_online_cpu(unsigned int cpu) { start_cpu_timer(cpu); return 0; } static int slab_offline_cpu(unsigned int cpu) { /* * Shutdown cache reaper. Note that the slab_mutex is held so * that if cache_reap() is invoked it cannot do anything * expensive but will only modify reap_work and reschedule the * timer. */ cancel_delayed_work_sync(&per_cpu(slab_reap_work, cpu)); /* Now the cache_reaper is guaranteed to be not running. */ per_cpu(slab_reap_work, cpu).work.func = NULL; return 0; } #if defined(CONFIG_NUMA) /* * Drains freelist for a node on each slab cache, used for memory hot-remove. * Returns -EBUSY if all objects cannot be drained so that the node is not * removed. * * Must hold slab_mutex. */ static int __meminit drain_cache_node_node(int node) { struct kmem_cache *cachep; int ret = 0; list_for_each_entry(cachep, &slab_caches, list) { struct kmem_cache_node *n; n = get_node(cachep, node); if (!n) continue; drain_freelist(cachep, n, INT_MAX); if (!list_empty(&n->slabs_full) || !list_empty(&n->slabs_partial)) { ret = -EBUSY; break; } } return ret; } static int __meminit slab_memory_callback(struct notifier_block *self, unsigned long action, void *arg) { struct memory_notify *mnb = arg; int ret = 0; int nid; nid = mnb->status_change_nid; if (nid < 0) goto out; switch (action) { case MEM_GOING_ONLINE: mutex_lock(&slab_mutex); ret = init_cache_node_node(nid); mutex_unlock(&slab_mutex); break; case MEM_GOING_OFFLINE: mutex_lock(&slab_mutex); ret = drain_cache_node_node(nid); mutex_unlock(&slab_mutex); break; case MEM_ONLINE: case MEM_OFFLINE: case MEM_CANCEL_ONLINE: case MEM_CANCEL_OFFLINE: break; } out: return notifier_from_errno(ret); } #endif /* CONFIG_NUMA */ /* * swap the static kmem_cache_node with kmalloced memory */ static void __init init_list(struct kmem_cache *cachep, struct kmem_cache_node *list, int nodeid) { struct kmem_cache_node *ptr; ptr = kmalloc_node(sizeof(struct kmem_cache_node), GFP_NOWAIT, nodeid); BUG_ON(!ptr); memcpy(ptr, list, sizeof(struct kmem_cache_node)); /* * Do not assume that spinlocks can be initialized via memcpy: */ spin_lock_init(&ptr->list_lock); MAKE_ALL_LISTS(cachep, ptr, nodeid); cachep->node[nodeid] = ptr; } /* * For setting up all the kmem_cache_node for cache whose buffer_size is same as * size of kmem_cache_node. */ static void __init set_up_node(struct kmem_cache *cachep, int index) { int node; for_each_online_node(node) { cachep->node[node] = &init_kmem_cache_node[index + node]; cachep->node[node]->next_reap = jiffies + REAPTIMEOUT_NODE + ((unsigned long)cachep) % REAPTIMEOUT_NODE; } } /* * Initialisation. Called after the page allocator have been initialised and * before smp_init(). */ void __init kmem_cache_init(void) { int i; kmem_cache = &kmem_cache_boot; if (!IS_ENABLED(CONFIG_NUMA) || num_possible_nodes() == 1) use_alien_caches = 0; for (i = 0; i < NUM_INIT_LISTS; i++) kmem_cache_node_init(&init_kmem_cache_node[i]); /* * Fragmentation resistance on low memory - only use bigger * page orders on machines with more than 32MB of memory if * not overridden on the command line. */ if (!slab_max_order_set && totalram_pages() > (32 << 20) >> PAGE_SHIFT) slab_max_order = SLAB_MAX_ORDER_HI; /* Bootstrap is tricky, because several objects are allocated * from caches that do not exist yet: * 1) initialize the kmem_cache cache: it contains the struct * kmem_cache structures of all caches, except kmem_cache itself: * kmem_cache is statically allocated. * Initially an __init data area is used for the head array and the * kmem_cache_node structures, it's replaced with a kmalloc allocated * array at the end of the bootstrap. * 2) Create the first kmalloc cache. * The struct kmem_cache for the new cache is allocated normally. * An __init data area is used for the head array. * 3) Create the remaining kmalloc caches, with minimally sized * head arrays. * 4) Replace the __init data head arrays for kmem_cache and the first * kmalloc cache with kmalloc allocated arrays. * 5) Replace the __init data for kmem_cache_node for kmem_cache and * the other cache's with kmalloc allocated memory. * 6) Resize the head arrays of the kmalloc caches to their final sizes. */ /* 1) create the kmem_cache */ /* * struct kmem_cache size depends on nr_node_ids & nr_cpu_ids */ create_boot_cache(kmem_cache, "kmem_cache", offsetof(struct kmem_cache, node) + nr_node_ids * sizeof(struct kmem_cache_node *), SLAB_HWCACHE_ALIGN, 0, 0); list_add(&kmem_cache->list, &slab_caches); slab_state = PARTIAL; /* * Initialize the caches that provide memory for the kmem_cache_node * structures first. Without this, further allocations will bug. */ kmalloc_caches[KMALLOC_NORMAL][INDEX_NODE] = create_kmalloc_cache( kmalloc_info[INDEX_NODE].name[KMALLOC_NORMAL], kmalloc_info[INDEX_NODE].size, ARCH_KMALLOC_FLAGS, 0, kmalloc_info[INDEX_NODE].size); slab_state = PARTIAL_NODE; setup_kmalloc_cache_index_table(); slab_early_init = 0; /* 5) Replace the bootstrap kmem_cache_node */ { int nid; for_each_online_node(nid) { init_list(kmem_cache, &init_kmem_cache_node[CACHE_CACHE + nid], nid); init_list(kmalloc_caches[KMALLOC_NORMAL][INDEX_NODE], &init_kmem_cache_node[SIZE_NODE + nid], nid); } } create_kmalloc_caches(ARCH_KMALLOC_FLAGS); } void __init kmem_cache_init_late(void) { struct kmem_cache *cachep; /* 6) resize the head arrays to their final sizes */ mutex_lock(&slab_mutex); list_for_each_entry(cachep, &slab_caches, list) if (enable_cpucache(cachep, GFP_NOWAIT)) BUG(); mutex_unlock(&slab_mutex); /* Done! */ slab_state = FULL; #ifdef CONFIG_NUMA /* * Register a memory hotplug callback that initializes and frees * node. */ hotplug_memory_notifier(slab_memory_callback, SLAB_CALLBACK_PRI); #endif /* * The reap timers are started later, with a module init call: That part * of the kernel is not yet operational. */ } static int __init cpucache_init(void) { int ret; /* * Register the timers that return unneeded pages to the page allocator */ ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "SLAB online", slab_online_cpu, slab_offline_cpu); WARN_ON(ret < 0); return 0; } __initcall(cpucache_init); static noinline void slab_out_of_memory(struct kmem_cache *cachep, gfp_t gfpflags, int nodeid) { #if DEBUG struct kmem_cache_node *n; unsigned long flags; int node; static DEFINE_RATELIMIT_STATE(slab_oom_rs, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST); if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slab_oom_rs)) return; pr_warn("SLAB: Unable to allocate memory on node %d, gfp=%#x(%pGg)\n", nodeid, gfpflags, &gfpflags); pr_warn(" cache: %s, object size: %d, order: %d\n", cachep->name, cachep->size, cachep->gfporder); for_each_kmem_cache_node(cachep, node, n) { unsigned long total_slabs, free_slabs, free_objs; spin_lock_irqsave(&n->list_lock, flags); total_slabs = n->total_slabs; free_slabs = n->free_slabs; free_objs = n->free_objects; spin_unlock_irqrestore(&n->list_lock, flags); pr_warn(" node %d: slabs: %ld/%ld, objs: %ld/%ld\n", node, total_slabs - free_slabs, total_slabs, (total_slabs * cachep->num) - free_objs, total_slabs * cachep->num); } #endif } /* * Interface to system's page allocator. No need to hold the * kmem_cache_node ->list_lock. * * If we requested dmaable memory, we will get it. Even if we * did not request dmaable memory, we might get it, but that * would be relatively rare and ignorable. */ static struct slab *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid) { struct folio *folio; struct slab *slab; flags |= cachep->allocflags; folio = (struct folio *) __alloc_pages_node(nodeid, flags, cachep->gfporder); if (!folio) { slab_out_of_memory(cachep, flags, nodeid); return NULL; } slab = folio_slab(folio); account_slab(slab, cachep->gfporder, cachep, flags); __folio_set_slab(folio); /* Record if ALLOC_NO_WATERMARKS was set when allocating the slab */ if (sk_memalloc_socks() && page_is_pfmemalloc(folio_page(folio, 0))) slab_set_pfmemalloc(slab); return slab; } /* * Interface to system's page release. */ static void kmem_freepages(struct kmem_cache *cachep, struct slab *slab) { int order = cachep->gfporder; struct folio *folio = slab_folio(slab); BUG_ON(!folio_test_slab(folio)); __slab_clear_pfmemalloc(slab); __folio_clear_slab(folio); page_mapcount_reset(folio_page(folio, 0)); folio->mapping = NULL; if (current->reclaim_state) current->reclaim_state->reclaimed_slab += 1 << order; unaccount_slab(slab, order, cachep); __free_pages(folio_page(folio, 0), order); } static void kmem_rcu_free(struct rcu_head *head) { struct kmem_cache *cachep; struct slab *slab; slab = container_of(head, struct slab, rcu_head); cachep = slab->slab_cache; kmem_freepages(cachep, slab); } #if DEBUG static bool is_debug_pagealloc_cache(struct kmem_cache *cachep) { if (debug_pagealloc_enabled_static() && OFF_SLAB(cachep) && (cachep->size % PAGE_SIZE) == 0) return true; return false; } #ifdef CONFIG_DEBUG_PAGEALLOC static void slab_kernel_map(struct kmem_cache *cachep, void *objp, int map) { if (!is_debug_pagealloc_cache(cachep)) return; __kernel_map_pages(virt_to_page(objp), cachep->size / PAGE_SIZE, map); } #else static inline void slab_kernel_map(struct kmem_cache *cachep, void *objp, int map) {} #endif static void poison_obj(struct kmem_cache *cachep, void *addr, unsigned char val) { int size = cachep->object_size; addr = &((char *)addr)[obj_offset(cachep)]; memset(addr, val, size); *(unsigned char *)(addr + size - 1) = POISON_END; } static void dump_line(char *data, int offset, int limit) { int i; unsigned char error = 0; int bad_count = 0; pr_err("%03x: ", offset); for (i = 0; i < limit; i++) { if (data[offset + i] != POISON_FREE) { error = data[offset + i]; bad_count++; } } print_hex_dump(KERN_CONT, "", 0, 16, 1, &data[offset], limit, 1); if (bad_count == 1) { error ^= POISON_FREE; if (!(error & (error - 1))) { pr_err("Single bit error detected. Probably bad RAM.\n"); #ifdef CONFIG_X86 pr_err("Run memtest86+ or a similar memory test tool.\n"); #else pr_err("Run a memory test tool.\n"); #endif } } } #endif #if DEBUG static void print_objinfo(struct kmem_cache *cachep, void *objp, int lines) { int i, size; char *realobj; if (cachep->flags & SLAB_RED_ZONE) { pr_err("Redzone: 0x%llx/0x%llx\n", *dbg_redzone1(cachep, objp), *dbg_redzone2(cachep, objp)); } if (cachep->flags & SLAB_STORE_USER) pr_err("Last user: (%pSR)\n", *dbg_userword(cachep, objp)); realobj = (char *)objp + obj_offset(cachep); size = cachep->object_size; for (i = 0; i < size && lines; i += 16, lines--) { int limit; limit = 16; if (i + limit > size) limit = size - i; dump_line(realobj, i, limit); } } static void check_poison_obj(struct kmem_cache *cachep, void *objp) { char *realobj; int size, i; int lines = 0; if (is_debug_pagealloc_cache(cachep)) return; realobj = (char *)objp + obj_offset(cachep); size = cachep->object_size; for (i = 0; i < size; i++) { char exp = POISON_FREE; if (i == size - 1) exp = POISON_END; if (realobj[i] != exp) { int limit; /* Mismatch ! */ /* Print header */ if (lines == 0) { pr_err("Slab corruption (%s): %s start=%px, len=%d\n", print_tainted(), cachep->name, realobj, size); print_objinfo(cachep, objp, 0); } /* Hexdump the affected line */ i = (i / 16) * 16; limit = 16; if (i + limit > size) limit = size - i; dump_line(realobj, i, limit); i += 16; lines++; /* Limit to 5 lines */ if (lines > 5) break; } } if (lines != 0) { /* Print some data about the neighboring objects, if they * exist: */ struct slab *slab = virt_to_slab(objp); unsigned int objnr; objnr = obj_to_index(cachep, slab, objp); if (objnr) { objp = index_to_obj(cachep, slab, objnr - 1); realobj = (char *)objp + obj_offset(cachep); pr_err("Prev obj: start=%px, len=%d\n", realobj, size); print_objinfo(cachep, objp, 2); } if (objnr + 1 < cachep->num) { objp = index_to_obj(cachep, slab, objnr + 1); realobj = (char *)objp + obj_offset(cachep); pr_err("Next obj: start=%px, len=%d\n", realobj, size); print_objinfo(cachep, objp, 2); } } } #endif #if DEBUG static void slab_destroy_debugcheck(struct kmem_cache *cachep, struct slab *slab) { int i; if (OBJFREELIST_SLAB(cachep) && cachep->flags & SLAB_POISON) { poison_obj(cachep, slab->freelist - obj_offset(cachep), POISON_FREE); } for (i = 0; i < cachep->num; i++) { void *objp = index_to_obj(cachep, slab, i); if (cachep->flags & SLAB_POISON) { check_poison_obj(cachep, objp); slab_kernel_map(cachep, objp, 1); } if (cachep->flags & SLAB_RED_ZONE) { if (*dbg_redzone1(cachep, objp) != RED_INACTIVE) slab_error(cachep, "start of a freed object was overwritten"); if (*dbg_redzone2(cachep, objp) != RED_INACTIVE) slab_error(cachep, "end of a freed object was overwritten"); } } } #else static void slab_destroy_debugcheck(struct kmem_cache *cachep, struct slab *slab) { } #endif /** * slab_destroy - destroy and release all objects in a slab * @cachep: cache pointer being destroyed * @slab: slab being destroyed * * Destroy all the objs in a slab, and release the mem back to the system. * Before calling the slab must have been unlinked from the cache. The * kmem_cache_node ->list_lock is not held/needed. */ static void slab_destroy(struct kmem_cache *cachep, struct slab *slab) { void *freelist; freelist = slab->freelist; slab_destroy_debugcheck(cachep, slab); if (unlikely(cachep->flags & SLAB_TYPESAFE_BY_RCU)) call_rcu(&slab->rcu_head, kmem_rcu_free); else kmem_freepages(cachep, slab); /* * From now on, we don't use freelist * although actual page can be freed in rcu context */ if (OFF_SLAB(cachep)) kmem_cache_free(cachep->freelist_cache, freelist); } /* * Update the size of the caches before calling slabs_destroy as it may * recursively call kfree. */ static void slabs_destroy(struct kmem_cache *cachep, struct list_head *list) { struct slab *slab, *n; list_for_each_entry_safe(slab, n, list, slab_list) { list_del(&slab->slab_list); slab_destroy(cachep, slab); } } /** * calculate_slab_order - calculate size (page order) of slabs * @cachep: pointer to the cache that is being created * @size: size of objects to be created in this cache. * @flags: slab allocation flags * * Also calculates the number of objects per slab. * * This could be made much more intelligent. For now, try to avoid using * high order pages for slabs. When the gfp() functions are more friendly * towards high-order requests, this should be changed. * * Return: number of left-over bytes in a slab */ static size_t calculate_slab_order(struct kmem_cache *cachep, size_t size, slab_flags_t flags) { size_t left_over = 0; int gfporder; for (gfporder = 0; gfporder <= KMALLOC_MAX_ORDER; gfporder++) { unsigned int num; size_t remainder; num = cache_estimate(gfporder, size, flags, &remainder); if (!num) continue; /* Can't handle number of objects more than SLAB_OBJ_MAX_NUM */ if (num > SLAB_OBJ_MAX_NUM) break; if (flags & CFLGS_OFF_SLAB) { struct kmem_cache *freelist_cache; size_t freelist_size; freelist_size = num * sizeof(freelist_idx_t); freelist_cache = kmalloc_slab(freelist_size, 0u); if (!freelist_cache) continue; /* * Needed to avoid possible looping condition * in cache_grow_begin() */ if (OFF_SLAB(freelist_cache)) continue; /* check if off slab has enough benefit */ if (freelist_cache->size > cachep->size / 2) continue; } /* Found something acceptable - save it away */ cachep->num = num; cachep->gfporder = gfporder; left_over = remainder; /* * A VFS-reclaimable slab tends to have most allocations * as GFP_NOFS and we really don't want to have to be allocating * higher-order pages when we are unable to shrink dcache. */ if (flags & SLAB_RECLAIM_ACCOUNT) break; /* * Large number of objects is good, but very large slabs are * currently bad for the gfp()s. */ if (gfporder >= slab_max_order) break; /* * Acceptable internal fragmentation? */ if (left_over * 8 <= (PAGE_SIZE << gfporder)) break; } return left_over; } static struct array_cache __percpu *alloc_kmem_cache_cpus( struct kmem_cache *cachep, int entries, int batchcount) { int cpu; size_t size; struct array_cache __percpu *cpu_cache; size = sizeof(void *) * entries + sizeof(struct array_cache); cpu_cache = __alloc_percpu(size, sizeof(void *)); if (!cpu_cache) return NULL; for_each_possible_cpu(cpu) { init_arraycache(per_cpu_ptr(cpu_cache, cpu), entries, batchcount); } return cpu_cache; } static int __ref setup_cpu_cache(struct kmem_cache *cachep, gfp_t gfp) { if (slab_state >= FULL) return enable_cpucache(cachep, gfp); cachep->cpu_cache = alloc_kmem_cache_cpus(cachep, 1, 1); if (!cachep->cpu_cache) return 1; if (slab_state == DOWN) { /* Creation of first cache (kmem_cache). */ set_up_node(kmem_cache, CACHE_CACHE); } else if (slab_state == PARTIAL) { /* For kmem_cache_node */ set_up_node(cachep, SIZE_NODE); } else { int node; for_each_online_node(node) { cachep->node[node] = kmalloc_node( sizeof(struct kmem_cache_node), gfp, node); BUG_ON(!cachep->node[node]); kmem_cache_node_init(cachep->node[node]); } } cachep->node[numa_mem_id()]->next_reap = jiffies + REAPTIMEOUT_NODE + ((unsigned long)cachep) % REAPTIMEOUT_NODE; cpu_cache_get(cachep)->avail = 0; cpu_cache_get(cachep)->limit = BOOT_CPUCACHE_ENTRIES; cpu_cache_get(cachep)->batchcount = 1; cpu_cache_get(cachep)->touched = 0; cachep->batchcount = 1; cachep->limit = BOOT_CPUCACHE_ENTRIES; return 0; } slab_flags_t kmem_cache_flags(unsigned int object_size, slab_flags_t flags, const char *name) { return flags; } struct kmem_cache * __kmem_cache_alias(const char *name, unsigned int size, unsigned int align, slab_flags_t flags, void (*ctor)(void *)) { struct kmem_cache *cachep; cachep = find_mergeable(size, align, flags, name, ctor); if (cachep) { cachep->refcount++; /* * Adjust the object sizes so that we clear * the complete object on kzalloc. */ cachep->object_size = max_t(int, cachep->object_size, size); } return cachep; } static bool set_objfreelist_slab_cache(struct kmem_cache *cachep, size_t size, slab_flags_t flags) { size_t left; cachep->num = 0; /* * If slab auto-initialization on free is enabled, store the freelist * off-slab, so that its contents don't end up in one of the allocated * objects. */ if (unlikely(slab_want_init_on_free(cachep))) return false; if (cachep->ctor || flags & SLAB_TYPESAFE_BY_RCU) return false; left = calculate_slab_order(cachep, size, flags | CFLGS_OBJFREELIST_SLAB); if (!cachep->num) return false; if (cachep->num * sizeof(freelist_idx_t) > cachep->object_size) return false; cachep->colour = left / cachep->colour_off; return true; } static bool set_off_slab_cache(struct kmem_cache *cachep, size_t size, slab_flags_t flags) { size_t left; cachep->num = 0; /* * Always use on-slab management when SLAB_NOLEAKTRACE * to avoid recursive calls into kmemleak. */ if (flags & SLAB_NOLEAKTRACE) return false; /* * Size is large, assume best to place the slab management obj * off-slab (should allow better packing of objs). */ left = calculate_slab_order(cachep, size, flags | CFLGS_OFF_SLAB); if (!cachep->num) return false; /* * If the slab has been placed off-slab, and we have enough space then * move it on-slab. This is at the expense of any extra colouring. */ if (left >= cachep->num * sizeof(freelist_idx_t)) return false; cachep->colour = left / cachep->colour_off; return true; } static bool set_on_slab_cache(struct kmem_cache *cachep, size_t size, slab_flags_t flags) { size_t left; cachep->num = 0; left = calculate_slab_order(cachep, size, flags); if (!cachep->num) return false; cachep->colour = left / cachep->colour_off; return true; } /** * __kmem_cache_create - Create a cache. * @cachep: cache management descriptor * @flags: SLAB flags * * Returns a ptr to the cache on success, NULL on failure. * Cannot be called within an int, but can be interrupted. * The @ctor is run when new pages are allocated by the cache. * * The flags are * * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) * to catch references to uninitialised memory. * * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check * for buffer overruns. * * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware * cacheline. This can be beneficial if you're counting cycles as closely * as davem. * * Return: a pointer to the created cache or %NULL in case of error */ int __kmem_cache_create(struct kmem_cache *cachep, slab_flags_t flags) { size_t ralign = BYTES_PER_WORD; gfp_t gfp; int err; unsigned int size = cachep->size; #if DEBUG #if FORCED_DEBUG /* * Enable redzoning and last user accounting, except for caches with * large objects, if the increased size would increase the object size * above the next power of two: caches with object sizes just above a * power of two have a significant amount of internal fragmentation. */ if (size < 4096 || fls(size - 1) == fls(size-1 + REDZONE_ALIGN + 2 * sizeof(unsigned long long))) flags |= SLAB_RED_ZONE | SLAB_STORE_USER; if (!(flags & SLAB_TYPESAFE_BY_RCU)) flags |= SLAB_POISON; #endif #endif /* * Check that size is in terms of words. This is needed to avoid * unaligned accesses for some archs when redzoning is used, and makes * sure any on-slab bufctl's are also correctly aligned. */ size = ALIGN(size, BYTES_PER_WORD); if (flags & SLAB_RED_ZONE) { ralign = REDZONE_ALIGN; /* If redzoning, ensure that the second redzone is suitably * aligned, by adjusting the object size accordingly. */ size = ALIGN(size, REDZONE_ALIGN); } /* 3) caller mandated alignment */ if (ralign < cachep->align) { ralign = cachep->align; } /* disable debug if necessary */ if (ralign > __alignof__(unsigned long long)) flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER); /* * 4) Store it. */ cachep->align = ralign; cachep->colour_off = cache_line_size(); /* Offset must be a multiple of the alignment. */ if (cachep->colour_off < cachep->align) cachep->colour_off = cachep->align; if (slab_is_available()) gfp = GFP_KERNEL; else gfp = GFP_NOWAIT; #if DEBUG /* * Both debugging options require word-alignment which is calculated * into align above. */ if (flags & SLAB_RED_ZONE) { /* add space for red zone words */ cachep->obj_offset += sizeof(unsigned long long); size += 2 * sizeof(unsigned long long); } if (flags & SLAB_STORE_USER) { /* user store requires one word storage behind the end of * the real object. But if the second red zone needs to be * aligned to 64 bits, we must allow that much space. */ if (flags & SLAB_RED_ZONE) size += REDZONE_ALIGN; else size += BYTES_PER_WORD; } #endif kasan_cache_create(cachep, &size, &flags); size = ALIGN(size, cachep->align); /* * We should restrict the number of objects in a slab to implement * byte sized index. Refer comment on SLAB_OBJ_MIN_SIZE definition. */ if (FREELIST_BYTE_INDEX && size < SLAB_OBJ_MIN_SIZE) size = ALIGN(SLAB_OBJ_MIN_SIZE, cachep->align); #if DEBUG /* * To activate debug pagealloc, off-slab management is necessary * requirement. In early phase of initialization, small sized slab * doesn't get initialized so it would not be possible. So, we need * to check size >= 256. It guarantees that all necessary small * sized slab is initialized in current slab initialization sequence. */ if (debug_pagealloc_enabled_static() && (flags & SLAB_POISON) && size >= 256 && cachep->object_size > cache_line_size()) { if (size < PAGE_SIZE || size % PAGE_SIZE == 0) { size_t tmp_size = ALIGN(size, PAGE_SIZE); if (set_off_slab_cache(cachep, tmp_size, flags)) { flags |= CFLGS_OFF_SLAB; cachep->obj_offset += tmp_size - size; size = tmp_size; goto done; } } } #endif if (set_objfreelist_slab_cache(cachep, size, flags)) { flags |= CFLGS_OBJFREELIST_SLAB; goto done; } if (set_off_slab_cache(cachep, size, flags)) { flags |= CFLGS_OFF_SLAB; goto done; } if (set_on_slab_cache(cachep, size, flags)) goto done; return -E2BIG; done: cachep->freelist_size = cachep->num * sizeof(freelist_idx_t); cachep->flags = flags; cachep->allocflags = __GFP_COMP; if (flags & SLAB_CACHE_DMA) cachep->allocflags |= GFP_DMA; if (flags & SLAB_CACHE_DMA32) cachep->allocflags |= GFP_DMA32; if (flags & SLAB_RECLAIM_ACCOUNT) cachep->allocflags |= __GFP_RECLAIMABLE; cachep->size = size; cachep->reciprocal_buffer_size = reciprocal_value(size); #if DEBUG /* * If we're going to use the generic kernel_map_pages() * poisoning, then it's going to smash the contents of * the redzone and userword anyhow, so switch them off. */ if (IS_ENABLED(CONFIG_PAGE_POISONING) && (cachep->flags & SLAB_POISON) && is_debug_pagealloc_cache(cachep)) cachep->flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER); #endif if (OFF_SLAB(cachep)) { cachep->freelist_cache = kmalloc_slab(cachep->freelist_size, 0u); } err = setup_cpu_cache(cachep, gfp); if (err) { __kmem_cache_release(cachep); return err; } return 0; } #if DEBUG static void check_irq_off(void) { BUG_ON(!irqs_disabled()); } static void check_irq_on(void) { BUG_ON(irqs_disabled()); } static void check_mutex_acquired(void) { BUG_ON(!mutex_is_locked(&slab_mutex)); } static void check_spinlock_acquired(struct kmem_cache *cachep) { #ifdef CONFIG_SMP check_irq_off(); assert_spin_locked(&get_node(cachep, numa_mem_id())->list_lock); #endif } static void check_spinlock_acquired_node(struct kmem_cache *cachep, int node) { #ifdef CONFIG_SMP check_irq_off(); assert_spin_locked(&get_node(cachep, node)->list_lock); #endif } #else #define check_irq_off() do { } while(0) #define check_irq_on() do { } while(0) #define check_mutex_acquired() do { } while(0) #define check_spinlock_acquired(x) do { } while(0) #define check_spinlock_acquired_node(x, y) do { } while(0) #endif static void drain_array_locked(struct kmem_cache *cachep, struct array_cache *ac, int node, bool free_all, struct list_head *list) { int tofree; if (!ac || !ac->avail) return; tofree = free_all ? ac->avail : (ac->limit + 4) / 5; if (tofree > ac->avail) tofree = (ac->avail + 1) / 2; free_block(cachep, ac->entry, tofree, node, list); ac->avail -= tofree; memmove(ac->entry, &(ac->entry[tofree]), sizeof(void *) * ac->avail); } static void do_drain(void *arg) { struct kmem_cache *cachep = arg; struct array_cache *ac; int node = numa_mem_id(); struct kmem_cache_node *n; LIST_HEAD(list); check_irq_off(); ac = cpu_cache_get(cachep); n = get_node(cachep, node); spin_lock(&n->list_lock); free_block(cachep, ac->entry, ac->avail, node, &list); spin_unlock(&n->list_lock); ac->avail = 0; slabs_destroy(cachep, &list); } static void drain_cpu_caches(struct kmem_cache *cachep) { struct kmem_cache_node *n; int node; LIST_HEAD(list); on_each_cpu(do_drain, cachep, 1); check_irq_on(); for_each_kmem_cache_node(cachep, node, n) if (n->alien) drain_alien_cache(cachep, n->alien); for_each_kmem_cache_node(cachep, node, n) { spin_lock_irq(&n->list_lock); drain_array_locked(cachep, n->shared, node, true, &list); spin_unlock_irq(&n->list_lock); slabs_destroy(cachep, &list); } } /* * Remove slabs from the list of free slabs. * Specify the number of slabs to drain in tofree. * * Returns the actual number of slabs released. */ static int drain_freelist(struct kmem_cache *cache, struct kmem_cache_node *n, int tofree) { struct list_head *p; int nr_freed; struct slab *slab; nr_freed = 0; while (nr_freed < tofree && !list_empty(&n->slabs_free)) { spin_lock_irq(&n->list_lock); p = n->slabs_free.prev; if (p == &n->slabs_free) { spin_unlock_irq(&n->list_lock); goto out; } slab = list_entry(p, struct slab, slab_list); list_del(&slab->slab_list); n->free_slabs--; n->total_slabs--; /* * Safe to drop the lock. The slab is no longer linked * to the cache. */ n->free_objects -= cache->num; spin_unlock_irq(&n->list_lock); slab_destroy(cache, slab); nr_freed++; } out: return nr_freed; } bool __kmem_cache_empty(struct kmem_cache *s) { int node; struct kmem_cache_node *n; for_each_kmem_cache_node(s, node, n) if (!list_empty(&n->slabs_full) || !list_empty(&n->slabs_partial)) return false; return true; } int __kmem_cache_shrink(struct kmem_cache *cachep) { int ret = 0; int node; struct kmem_cache_node *n; drain_cpu_caches(cachep); check_irq_on(); for_each_kmem_cache_node(cachep, node, n) { drain_freelist(cachep, n, INT_MAX); ret += !list_empty(&n->slabs_full) || !list_empty(&n->slabs_partial); } return (ret ? 1 : 0); } int __kmem_cache_shutdown(struct kmem_cache *cachep) { return __kmem_cache_shrink(cachep); } void __kmem_cache_release(struct kmem_cache *cachep) { int i; struct kmem_cache_node *n; cache_random_seq_destroy(cachep); free_percpu(cachep->cpu_cache); /* NUMA: free the node structures */ for_each_kmem_cache_node(cachep, i, n) { kfree(n->shared); free_alien_cache(n->alien); kfree(n); cachep->node[i] = NULL; } } /* * Get the memory for a slab management obj. * * For a slab cache when the slab descriptor is off-slab, the * slab descriptor can't come from the same cache which is being created, * Because if it is the case, that means we defer the creation of * the kmalloc_{dma,}_cache of size sizeof(slab descriptor) to this point. * And we eventually call down to __kmem_cache_create(), which * in turn looks up in the kmalloc_{dma,}_caches for the desired-size one. * This is a "chicken-and-egg" problem. * * So the off-slab slab descriptor shall come from the kmalloc_{dma,}_caches, * which are all initialized during kmem_cache_init(). */ static void *alloc_slabmgmt(struct kmem_cache *cachep, struct slab *slab, int colour_off, gfp_t local_flags, int nodeid) { void *freelist; void *addr = slab_address(slab); slab->s_mem = addr + colour_off; slab->active = 0; if (OBJFREELIST_SLAB(cachep)) freelist = NULL; else if (OFF_SLAB(cachep)) { /* Slab management obj is off-slab. */ freelist = kmem_cache_alloc_node(cachep->freelist_cache, local_flags, nodeid); } else { /* We will use last bytes at the slab for freelist */ freelist = addr + (PAGE_SIZE << cachep->gfporder) - cachep->freelist_size; } return freelist; } static inline freelist_idx_t get_free_obj(struct slab *slab, unsigned int idx) { return ((freelist_idx_t *) slab->freelist)[idx]; } static inline void set_free_obj(struct slab *slab, unsigned int idx, freelist_idx_t val) { ((freelist_idx_t *)(slab->freelist))[idx] = val; } static void cache_init_objs_debug(struct kmem_cache *cachep, struct slab *slab) { #if DEBUG int i; for (i = 0; i < cachep->num; i++) { void *objp = index_to_obj(cachep, slab, i); if (cachep->flags & SLAB_STORE_USER) *dbg_userword(cachep, objp) = NULL; if (cachep->flags & SLAB_RED_ZONE) { *dbg_redzone1(cachep, objp) = RED_INACTIVE; *dbg_redzone2(cachep, objp) = RED_INACTIVE; } /* * Constructors are not allowed to allocate memory from the same * cache which they are a constructor for. Otherwise, deadlock. * They must also be threaded. */ if (cachep->ctor && !(cachep->flags & SLAB_POISON)) { kasan_unpoison_object_data(cachep, objp + obj_offset(cachep)); cachep->ctor(objp + obj_offset(cachep)); kasan_poison_object_data( cachep, objp + obj_offset(cachep)); } if (cachep->flags & SLAB_RED_ZONE) { if (*dbg_redzone2(cachep, objp) != RED_INACTIVE) slab_error(cachep, "constructor overwrote the end of an object"); if (*dbg_redzone1(cachep, objp) != RED_INACTIVE) slab_error(cachep, "constructor overwrote the start of an object"); } /* need to poison the objs? */ if (cachep->flags & SLAB_POISON) { poison_obj(cachep, objp, POISON_FREE); slab_kernel_map(cachep, objp, 0); } } #endif } #ifdef CONFIG_SLAB_FREELIST_RANDOM /* Hold information during a freelist initialization */ union freelist_init_state { struct { unsigned int pos; unsigned int *list; unsigned int count; }; struct rnd_state rnd_state; }; /* * Initialize the state based on the randomization method available. * return true if the pre-computed list is available, false otherwise. */ static bool freelist_state_initialize(union freelist_init_state *state, struct kmem_cache *cachep, unsigned int count) { bool ret; unsigned int rand; /* Use best entropy available to define a random shift */ rand = get_random_int(); /* Use a random state if the pre-computed list is not available */ if (!cachep->random_seq) { prandom_seed_state(&state->rnd_state, rand); ret = false; } else { state->list = cachep->random_seq; state->count = count; state->pos = rand % count; ret = true; } return ret; } /* Get the next entry on the list and randomize it using a random shift */ static freelist_idx_t next_random_slot(union freelist_init_state *state) { if (state->pos >= state->count) state->pos = 0; return state->list[state->pos++]; } /* Swap two freelist entries */ static void swap_free_obj(struct slab *slab, unsigned int a, unsigned int b) { swap(((freelist_idx_t *) slab->freelist)[a], ((freelist_idx_t *) slab->freelist)[b]); } /* * Shuffle the freelist initialization state based on pre-computed lists. * return true if the list was successfully shuffled, false otherwise. */ static bool shuffle_freelist(struct kmem_cache *cachep, struct slab *slab) { unsigned int objfreelist = 0, i, rand, count = cachep->num; union freelist_init_state state; bool precomputed; if (count < 2) return false; precomputed = freelist_state_initialize(&state, cachep, count); /* Take a random entry as the objfreelist */ if (OBJFREELIST_SLAB(cachep)) { if (!precomputed) objfreelist = count - 1; else objfreelist = next_random_slot(&state); slab->freelist = index_to_obj(cachep, slab, objfreelist) + obj_offset(cachep); count--; } /* * On early boot, generate the list dynamically. * Later use a pre-computed list for speed. */ if (!precomputed) { for (i = 0; i < count; i++) set_free_obj(slab, i, i); /* Fisher-Yates shuffle */ for (i = count - 1; i > 0; i--) { rand = prandom_u32_state(&state.rnd_state); rand %= (i + 1); swap_free_obj(slab, i, rand); } } else { for (i = 0; i < count; i++) set_free_obj(slab, i, next_random_slot(&state)); } if (OBJFREELIST_SLAB(cachep)) set_free_obj(slab, cachep->num - 1, objfreelist); return true; } #else static inline bool shuffle_freelist(struct kmem_cache *cachep, struct slab *slab) { return false; } #endif /* CONFIG_SLAB_FREELIST_RANDOM */ static void cache_init_objs(struct kmem_cache *cachep, struct slab *slab) { int i; void *objp; bool shuffled; cache_init_objs_debug(cachep, slab); /* Try to randomize the freelist if enabled */ shuffled = shuffle_freelist(cachep, slab); if (!shuffled && OBJFREELIST_SLAB(cachep)) { slab->freelist = index_to_obj(cachep, slab, cachep->num - 1) + obj_offset(cachep); } for (i = 0; i < cachep->num; i++) { objp = index_to_obj(cachep, slab, i); objp = kasan_init_slab_obj(cachep, objp); /* constructor could break poison info */ if (DEBUG == 0 && cachep->ctor) { kasan_unpoison_object_data(cachep, objp); cachep->ctor(objp); kasan_poison_object_data(cachep, objp); } if (!shuffled) set_free_obj(slab, i, i); } } static void *slab_get_obj(struct kmem_cache *cachep, struct slab *slab) { void *objp; objp = index_to_obj(cachep, slab, get_free_obj(slab, slab->active)); slab->active++; return objp; } static void slab_put_obj(struct kmem_cache *cachep, struct slab *slab, void *objp) { unsigned int objnr = obj_to_index(cachep, slab, objp); #if DEBUG unsigned int i; /* Verify double free bug */ for (i = slab->active; i < cachep->num; i++) { if (get_free_obj(slab, i) == objnr) { pr_err("slab: double free detected in cache '%s', objp %px\n", cachep->name, objp); BUG(); } } #endif slab->active--; if (!slab->freelist) slab->freelist = objp + obj_offset(cachep); set_free_obj(slab, slab->active, objnr); } /* * Grow (by 1) the number of slabs within a cache. This is called by * kmem_cache_alloc() when there are no active objs left in a cache. */ static struct slab *cache_grow_begin(struct kmem_cache *cachep, gfp_t flags, int nodeid) { void *freelist; size_t offset; gfp_t local_flags; int slab_node; struct kmem_cache_node *n; struct slab *slab; /* * Be lazy and only check for valid flags here, keeping it out of the * critical path in kmem_cache_alloc(). */ if (unlikely(flags & GFP_SLAB_BUG_MASK)) flags = kmalloc_fix_flags(flags); WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO)); local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK); check_irq_off(); if (gfpflags_allow_blocking(local_flags)) local_irq_enable(); /* * Get mem for the objs. Attempt to allocate a physical page from * 'nodeid'. */ slab = kmem_getpages(cachep, local_flags, nodeid); if (!slab) goto failed; slab_node = slab_nid(slab); n = get_node(cachep, slab_node); /* Get colour for the slab, and cal the next value. */ n->colour_next++; if (n->colour_next >= cachep->colour) n->colour_next = 0; offset = n->colour_next; if (offset >= cachep->colour) offset = 0; offset *= cachep->colour_off; /* * Call kasan_poison_slab() before calling alloc_slabmgmt(), so * page_address() in the latter returns a non-tagged pointer, * as it should be for slab pages. */ kasan_poison_slab(slab); /* Get slab management. */ freelist = alloc_slabmgmt(cachep, slab, offset, local_flags & ~GFP_CONSTRAINT_MASK, slab_node); if (OFF_SLAB(cachep) && !freelist) goto opps1; slab->slab_cache = cachep; slab->freelist = freelist; cache_init_objs(cachep, slab); if (gfpflags_allow_blocking(local_flags)) local_irq_disable(); return slab; opps1: kmem_freepages(cachep, slab); failed: if (gfpflags_allow_blocking(local_flags)) local_irq_disable(); return NULL; } static void cache_grow_end(struct kmem_cache *cachep, struct slab *slab) { struct kmem_cache_node *n; void *list = NULL; check_irq_off(); if (!slab) return; INIT_LIST_HEAD(&slab->slab_list); n = get_node(cachep, slab_nid(slab)); spin_lock(&n->list_lock); n->total_slabs++; if (!slab->active) { list_add_tail(&slab->slab_list, &n->slabs_free); n->free_slabs++; } else fixup_slab_list(cachep, n, slab, &list); STATS_INC_GROWN(cachep); n->free_objects += cachep->num - slab->active; spin_unlock(&n->list_lock); fixup_objfreelist_debug(cachep, &list); } #if DEBUG /* * Perform extra freeing checks: * - detect bad pointers. * - POISON/RED_ZONE checking */ static void kfree_debugcheck(const void *objp) { if (!virt_addr_valid(objp)) { pr_err("kfree_debugcheck: out of range ptr %lxh\n", (unsigned long)objp); BUG(); } } static inline void verify_redzone_free(struct kmem_cache *cache, void *obj) { unsigned long long redzone1, redzone2; redzone1 = *dbg_redzone1(cache, obj); redzone2 = *dbg_redzone2(cache, obj); /* * Redzone is ok. */ if (redzone1 == RED_ACTIVE && redzone2 == RED_ACTIVE) return; if (redzone1 == RED_INACTIVE && redzone2 == RED_INACTIVE) slab_error(cache, "double free detected"); else slab_error(cache, "memory outside object was overwritten"); pr_err("%px: redzone 1:0x%llx, redzone 2:0x%llx\n", obj, redzone1, redzone2); } static void *cache_free_debugcheck(struct kmem_cache *cachep, void *objp, unsigned long caller) { unsigned int objnr; struct slab *slab; BUG_ON(virt_to_cache(objp) != cachep); objp -= obj_offset(cachep); kfree_debugcheck(objp); slab = virt_to_slab(objp); if (cachep->flags & SLAB_RED_ZONE) { verify_redzone_free(cachep, objp); *dbg_redzone1(cachep, objp) = RED_INACTIVE; *dbg_redzone2(cachep, objp) = RED_INACTIVE; } if (cachep->flags & SLAB_STORE_USER) *dbg_userword(cachep, objp) = (void *)caller; objnr = obj_to_index(cachep, slab, objp); BUG_ON(objnr >= cachep->num); BUG_ON(objp != index_to_obj(cachep, slab, objnr)); if (cachep->flags & SLAB_POISON) { poison_obj(cachep, objp, POISON_FREE); slab_kernel_map(cachep, objp, 0); } return objp; } #else #define kfree_debugcheck(x) do { } while(0) #define cache_free_debugcheck(x, objp, z) (objp) #endif static inline void fixup_objfreelist_debug(struct kmem_cache *cachep, void **list) { #if DEBUG void *next = *list; void *objp; while (next) { objp = next - obj_offset(cachep); next = *(void **)next; poison_obj(cachep, objp, POISON_FREE); } #endif } static inline void fixup_slab_list(struct kmem_cache *cachep, struct kmem_cache_node *n, struct slab *slab, void **list) { /* move slabp to correct slabp list: */ list_del(&slab->slab_list); if (slab->active == cachep->num) { list_add(&slab->slab_list, &n->slabs_full); if (OBJFREELIST_SLAB(cachep)) { #if DEBUG /* Poisoning will be done without holding the lock */ if (cachep->flags & SLAB_POISON) { void **objp = slab->freelist; *objp = *list; *list = objp; } #endif slab->freelist = NULL; } } else list_add(&slab->slab_list, &n->slabs_partial); } /* Try to find non-pfmemalloc slab if needed */ static noinline struct slab *get_valid_first_slab(struct kmem_cache_node *n, struct slab *slab, bool pfmemalloc) { if (!slab) return NULL; if (pfmemalloc) return slab; if (!slab_test_pfmemalloc(slab)) return slab; /* No need to keep pfmemalloc slab if we have enough free objects */ if (n->free_objects > n->free_limit) { slab_clear_pfmemalloc(slab); return slab; } /* Move pfmemalloc slab to the end of list to speed up next search */ list_del(&slab->slab_list); if (!slab->active) { list_add_tail(&slab->slab_list, &n->slabs_free); n->free_slabs++; } else list_add_tail(&slab->slab_list, &n->slabs_partial); list_for_each_entry(slab, &n->slabs_partial, slab_list) { if (!slab_test_pfmemalloc(slab)) return slab; } n->free_touched = 1; list_for_each_entry(slab, &n->slabs_free, slab_list) { if (!slab_test_pfmemalloc(slab)) { n->free_slabs--; return slab; } } return NULL; } static struct slab *get_first_slab(struct kmem_cache_node *n, bool pfmemalloc) { struct slab *slab; assert_spin_locked(&n->list_lock); slab = list_first_entry_or_null(&n->slabs_partial, struct slab, slab_list); if (!slab) { n->free_touched = 1; slab = list_first_entry_or_null(&n->slabs_free, struct slab, slab_list); if (slab) n->free_slabs--; } if (sk_memalloc_socks()) slab = get_valid_first_slab(n, slab, pfmemalloc); return slab; } static noinline void *cache_alloc_pfmemalloc(struct kmem_cache *cachep, struct kmem_cache_node *n, gfp_t flags) { struct slab *slab; void *obj; void *list = NULL; if (!gfp_pfmemalloc_allowed(flags)) return NULL; spin_lock(&n->list_lock); slab = get_first_slab(n, true); if (!slab) { spin_unlock(&n->list_lock); return NULL; } obj = slab_get_obj(cachep, slab); n->free_objects--; fixup_slab_list(cachep, n, slab, &list); spin_unlock(&n->list_lock); fixup_objfreelist_debug(cachep, &list); return obj; } /* * Slab list should be fixed up by fixup_slab_list() for existing slab * or cache_grow_end() for new slab */ static __always_inline int alloc_block(struct kmem_cache *cachep, struct array_cache *ac, struct slab *slab, int batchcount) { /* * There must be at least one object available for * allocation. */ BUG_ON(slab->active >= cachep->num); while (slab->active < cachep->num && batchcount--) { STATS_INC_ALLOCED(cachep); STATS_INC_ACTIVE(cachep); STATS_SET_HIGH(cachep); ac->entry[ac->avail++] = slab_get_obj(cachep, slab); } return batchcount; } static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags) { int batchcount; struct kmem_cache_node *n; struct array_cache *ac, *shared; int node; void *list = NULL; struct slab *slab; check_irq_off(); node = numa_mem_id(); ac = cpu_cache_get(cachep); batchcount = ac->batchcount; if (!ac->touched && batchcount > BATCHREFILL_LIMIT) { /* * If there was little recent activity on this cache, then * perform only a partial refill. Otherwise we could generate * refill bouncing. */ batchcount = BATCHREFILL_LIMIT; } n = get_node(cachep, node); BUG_ON(ac->avail > 0 || !n); shared = READ_ONCE(n->shared); if (!n->free_objects && (!shared || !shared->avail)) goto direct_grow; spin_lock(&n->list_lock); shared = READ_ONCE(n->shared); /* See if we can refill from the shared array */ if (shared && transfer_objects(ac, shared, batchcount)) { shared->touched = 1; goto alloc_done; } while (batchcount > 0) { /* Get slab alloc is to come from. */ slab = get_first_slab(n, false); if (!slab) goto must_grow; check_spinlock_acquired(cachep); batchcount = alloc_block(cachep, ac, slab, batchcount); fixup_slab_list(cachep, n, slab, &list); } must_grow: n->free_objects -= ac->avail; alloc_done: spin_unlock(&n->list_lock); fixup_objfreelist_debug(cachep, &list); direct_grow: if (unlikely(!ac->avail)) { /* Check if we can use obj in pfmemalloc slab */ if (sk_memalloc_socks()) { void *obj = cache_alloc_pfmemalloc(cachep, n, flags); if (obj) return obj; } slab = cache_grow_begin(cachep, gfp_exact_node(flags), node); /* * cache_grow_begin() can reenable interrupts, * then ac could change. */ ac = cpu_cache_get(cachep); if (!ac->avail && slab) alloc_block(cachep, ac, slab, batchcount); cache_grow_end(cachep, slab); if (!ac->avail) return NULL; } ac->touched = 1; return ac->entry[--ac->avail]; } #if DEBUG static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep, gfp_t flags, void *objp, unsigned long caller) { WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO)); if (!objp || is_kfence_address(objp)) return objp; if (cachep->flags & SLAB_POISON) { check_poison_obj(cachep, objp); slab_kernel_map(cachep, objp, 1); poison_obj(cachep, objp, POISON_INUSE); } if (cachep->flags & SLAB_STORE_USER) *dbg_userword(cachep, objp) = (void *)caller; if (cachep->flags & SLAB_RED_ZONE) { if (*dbg_redzone1(cachep, objp) != RED_INACTIVE || *dbg_redzone2(cachep, objp) != RED_INACTIVE) { slab_error(cachep, "double free, or memory outside object was overwritten"); pr_err("%px: redzone 1:0x%llx, redzone 2:0x%llx\n", objp, *dbg_redzone1(cachep, objp), *dbg_redzone2(cachep, objp)); } *dbg_redzone1(cachep, objp) = RED_ACTIVE; *dbg_redzone2(cachep, objp) = RED_ACTIVE; } objp += obj_offset(cachep); if (cachep->ctor && cachep->flags & SLAB_POISON) cachep->ctor(objp); if ((unsigned long)objp & (arch_slab_minalign() - 1)) { pr_err("0x%px: not aligned to arch_slab_minalign()=%u\n", objp, arch_slab_minalign()); } return objp; } #else #define cache_alloc_debugcheck_after(a, b, objp, d) (objp) #endif static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags) { void *objp; struct array_cache *ac; check_irq_off(); ac = cpu_cache_get(cachep); if (likely(ac->avail)) { ac->touched = 1; objp = ac->entry[--ac->avail]; STATS_INC_ALLOCHIT(cachep); goto out; } STATS_INC_ALLOCMISS(cachep); objp = cache_alloc_refill(cachep, flags); /* * the 'ac' may be updated by cache_alloc_refill(), * and kmemleak_erase() requires its correct value. */ ac = cpu_cache_get(cachep); out: /* * To avoid a false negative, if an object that is in one of the * per-CPU caches is leaked, we need to make sure kmemleak doesn't * treat the array pointers as a reference to the object. */ if (objp) kmemleak_erase(&ac->entry[ac->avail]); return objp; } #ifdef CONFIG_NUMA static void *____cache_alloc_node(struct kmem_cache *, gfp_t, int); /* * Try allocating on another node if PFA_SPREAD_SLAB is a mempolicy is set. * * If we are in_interrupt, then process context, including cpusets and * mempolicy, may not apply and should not be used for allocation policy. */ static void *alternate_node_alloc(struct kmem_cache *cachep, gfp_t flags) { int nid_alloc, nid_here; if (in_interrupt() || (flags & __GFP_THISNODE)) return NULL; nid_alloc = nid_here = numa_mem_id(); if (cpuset_do_slab_mem_spread() && (cachep->flags & SLAB_MEM_SPREAD)) nid_alloc = cpuset_slab_spread_node(); else if (current->mempolicy) nid_alloc = mempolicy_slab_node(); if (nid_alloc != nid_here) return ____cache_alloc_node(cachep, flags, nid_alloc); return NULL; } /* * Fallback function if there was no memory available and no objects on a * certain node and fall back is permitted. First we scan all the * available node for available objects. If that fails then we * perform an allocation without specifying a node. This allows the page * allocator to do its reclaim / fallback magic. We then insert the * slab into the proper nodelist and then allocate from it. */ static void *fallback_alloc(struct kmem_cache *cache, gfp_t flags) { struct zonelist *zonelist; struct zoneref *z; struct zone *zone; enum zone_type highest_zoneidx = gfp_zone(flags); void *obj = NULL; struct slab *slab; int nid; unsigned int cpuset_mems_cookie; if (flags & __GFP_THISNODE) return NULL; retry_cpuset: cpuset_mems_cookie = read_mems_allowed_begin(); zonelist = node_zonelist(mempolicy_slab_node(), flags); retry: /* * Look through allowed nodes for objects available * from existing per node queues. */ for_each_zone_zonelist(zone, z, zonelist, highest_zoneidx) { nid = zone_to_nid(zone); if (cpuset_zone_allowed(zone, flags) && get_node(cache, nid) && get_node(cache, nid)->free_objects) { obj = ____cache_alloc_node(cache, gfp_exact_node(flags), nid); if (obj) break; } } if (!obj) { /* * This allocation will be performed within the constraints * of the current cpuset / memory policy requirements. * We may trigger various forms of reclaim on the allowed * set and go into memory reserves if necessary. */ slab = cache_grow_begin(cache, flags, numa_mem_id()); cache_grow_end(cache, slab); if (slab) { nid = slab_nid(slab); obj = ____cache_alloc_node(cache, gfp_exact_node(flags), nid); /* * Another processor may allocate the objects in * the slab since we are not holding any locks. */ if (!obj) goto retry; } } if (unlikely(!obj && read_mems_allowed_retry(cpuset_mems_cookie))) goto retry_cpuset; return obj; } /* * An interface to enable slab creation on nodeid */ static void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid) { struct slab *slab; struct kmem_cache_node *n; void *obj = NULL; void *list = NULL; VM_BUG_ON(nodeid < 0 || nodeid >= MAX_NUMNODES); n = get_node(cachep, nodeid); BUG_ON(!n); check_irq_off(); spin_lock(&n->list_lock); slab = get_first_slab(n, false); if (!slab) goto must_grow; check_spinlock_acquired_node(cachep, nodeid); STATS_INC_NODEALLOCS(cachep); STATS_INC_ACTIVE(cachep); STATS_SET_HIGH(cachep); BUG_ON(slab->active == cachep->num); obj = slab_get_obj(cachep, slab); n->free_objects--; fixup_slab_list(cachep, n, slab, &list); spin_unlock(&n->list_lock); fixup_objfreelist_debug(cachep, &list); return obj; must_grow: spin_unlock(&n->list_lock); slab = cache_grow_begin(cachep, gfp_exact_node(flags), nodeid); if (slab) { /* This slab isn't counted yet so don't update free_objects */ obj = slab_get_obj(cachep, slab); } cache_grow_end(cachep, slab); return obj ? obj : fallback_alloc(cachep, flags); } static void *__do_cache_alloc(struct kmem_cache *cachep, gfp_t flags, int nodeid); static __always_inline void * slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid, size_t orig_size, unsigned long caller) { unsigned long save_flags; void *ptr; struct obj_cgroup *objcg = NULL; bool init = false; flags &= gfp_allowed_mask; cachep = slab_pre_alloc_hook(cachep, NULL, &objcg, 1, flags); if (unlikely(!cachep)) return NULL; ptr = kfence_alloc(cachep, orig_size, flags); if (unlikely(ptr)) goto out_hooks; local_irq_save(save_flags); ptr = __do_cache_alloc(cachep, flags, nodeid); local_irq_restore(save_flags); ptr = cache_alloc_debugcheck_after(cachep, flags, ptr, caller); init = slab_want_init_on_alloc(flags, cachep); out_hooks: slab_post_alloc_hook(cachep, objcg, flags, 1, &ptr, init); return ptr; } static __always_inline void * __do_cache_alloc(struct kmem_cache *cachep, gfp_t flags, int nodeid) { void *objp = NULL; int slab_node = numa_mem_id(); if (nodeid == NUMA_NO_NODE) { if (current->mempolicy || cpuset_do_slab_mem_spread()) { objp = alternate_node_alloc(cachep, flags); if (objp) goto out; } /* * Use the locally cached objects if possible. * However ____cache_alloc does not allow fallback * to other nodes. It may fail while we still have * objects on other nodes available. */ objp = ____cache_alloc(cachep, flags); nodeid = slab_node; } else if (nodeid == slab_node) { objp = ____cache_alloc(cachep, flags); } else if (!get_node(cachep, nodeid)) { /* Node not bootstrapped yet */ objp = fallback_alloc(cachep, flags); goto out; } /* * We may just have run out of memory on the local node. * ____cache_alloc_node() knows how to locate memory on other nodes */ if (!objp) objp = ____cache_alloc_node(cachep, flags, nodeid); out: return objp; } #else static __always_inline void * __do_cache_alloc(struct kmem_cache *cachep, gfp_t flags, int nodeid __maybe_unused) { return ____cache_alloc(cachep, flags); } #endif /* CONFIG_NUMA */ static __always_inline void * slab_alloc(struct kmem_cache *cachep, struct list_lru *lru, gfp_t flags, size_t orig_size, unsigned long caller) { unsigned long save_flags; void *objp; struct obj_cgroup *objcg = NULL; bool init = false; flags &= gfp_allowed_mask; cachep = slab_pre_alloc_hook(cachep, lru, &objcg, 1, flags); if (unlikely(!cachep)) return NULL; objp = kfence_alloc(cachep, orig_size, flags); if (unlikely(objp)) goto out; local_irq_save(save_flags); objp = __do_cache_alloc(cachep, flags, NUMA_NO_NODE); local_irq_restore(save_flags); objp = cache_alloc_debugcheck_after(cachep, flags, objp, caller); prefetchw(objp); init = slab_want_init_on_alloc(flags, cachep); out: slab_post_alloc_hook(cachep, objcg, flags, 1, &objp, init); return objp; } /* * Caller needs to acquire correct kmem_cache_node's list_lock * @list: List of detached free slabs should be freed by caller */ static void free_block(struct kmem_cache *cachep, void **objpp, int nr_objects, int node, struct list_head *list) { int i; struct kmem_cache_node *n = get_node(cachep, node); struct slab *slab; n->free_objects += nr_objects; for (i = 0; i < nr_objects; i++) { void *objp; struct slab *slab; objp = objpp[i]; slab = virt_to_slab(objp); list_del(&slab->slab_list); check_spinlock_acquired_node(cachep, node); slab_put_obj(cachep, slab, objp); STATS_DEC_ACTIVE(cachep); /* fixup slab chains */ if (slab->active == 0) { list_add(&slab->slab_list, &n->slabs_free); n->free_slabs++; } else { /* Unconditionally move a slab to the end of the * partial list on free - maximum time for the * other objects to be freed, too. */ list_add_tail(&slab->slab_list, &n->slabs_partial); } } while (n->free_objects > n->free_limit && !list_empty(&n->slabs_free)) { n->free_objects -= cachep->num; slab = list_last_entry(&n->slabs_free, struct slab, slab_list); list_move(&slab->slab_list, list); n->free_slabs--; n->total_slabs--; } } static void cache_flusharray(struct kmem_cache *cachep, struct array_cache *ac) { int batchcount; struct kmem_cache_node *n; int node = numa_mem_id(); LIST_HEAD(list); batchcount = ac->batchcount; check_irq_off(); n = get_node(cachep, node); spin_lock(&n->list_lock); if (n->shared) { struct array_cache *shared_array = n->shared; int max = shared_array->limit - shared_array->avail; if (max) { if (batchcount > max) batchcount = max; memcpy(&(shared_array->entry[shared_array->avail]), ac->entry, sizeof(void *) * batchcount); shared_array->avail += batchcount; goto free_done; } } free_block(cachep, ac->entry, batchcount, node, &list); free_done: #if STATS { int i = 0; struct slab *slab; list_for_each_entry(slab, &n->slabs_free, slab_list) { BUG_ON(slab->active); i++; } STATS_SET_FREEABLE(cachep, i); } #endif spin_unlock(&n->list_lock); ac->avail -= batchcount; memmove(ac->entry, &(ac->entry[batchcount]), sizeof(void *)*ac->avail); slabs_destroy(cachep, &list); } /* * Release an obj back to its cache. If the obj has a constructed state, it must * be in this state _before_ it is released. Called with disabled ints. */ static __always_inline void __cache_free(struct kmem_cache *cachep, void *objp, unsigned long caller) { bool init; memcg_slab_free_hook(cachep, virt_to_slab(objp), &objp, 1); if (is_kfence_address(objp)) { kmemleak_free_recursive(objp, cachep->flags); __kfence_free(objp); return; } /* * As memory initialization might be integrated into KASAN, * kasan_slab_free and initialization memset must be * kept together to avoid discrepancies in behavior. */ init = slab_want_init_on_free(cachep); if (init && !kasan_has_integrated_init()) memset(objp, 0, cachep->object_size); /* KASAN might put objp into memory quarantine, delaying its reuse. */ if (kasan_slab_free(cachep, objp, init)) return; /* Use KCSAN to help debug racy use-after-free. */ if (!(cachep->flags & SLAB_TYPESAFE_BY_RCU)) __kcsan_check_access(objp, cachep->object_size, KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ASSERT); ___cache_free(cachep, objp, caller); } void ___cache_free(struct kmem_cache *cachep, void *objp, unsigned long caller) { struct array_cache *ac = cpu_cache_get(cachep); check_irq_off(); kmemleak_free_recursive(objp, cachep->flags); objp = cache_free_debugcheck(cachep, objp, caller); /* * Skip calling cache_free_alien() when the platform is not numa. * This will avoid cache misses that happen while accessing slabp (which * is per page memory reference) to get nodeid. Instead use a global * variable to skip the call, which is mostly likely to be present in * the cache. */ if (nr_online_nodes > 1 && cache_free_alien(cachep, objp)) return; if (ac->avail < ac->limit) { STATS_INC_FREEHIT(cachep); } else { STATS_INC_FREEMISS(cachep); cache_flusharray(cachep, ac); } if (sk_memalloc_socks()) { struct slab *slab = virt_to_slab(objp); if (unlikely(slab_test_pfmemalloc(slab))) { cache_free_pfmemalloc(cachep, slab, objp); return; } } __free_one(ac, objp); } static __always_inline void *__kmem_cache_alloc_lru(struct kmem_cache *cachep, struct list_lru *lru, gfp_t flags) { void *ret = slab_alloc(cachep, lru, flags, cachep->object_size, _RET_IP_); trace_kmem_cache_alloc(_RET_IP_, ret, cachep, cachep->object_size, cachep->size, flags); return ret; } /** * kmem_cache_alloc - Allocate an object * @cachep: The cache to allocate from. * @flags: See kmalloc(). * * Allocate an object from this cache. The flags are only relevant * if the cache has no available objects. * * Return: pointer to the new object or %NULL in case of error */ void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags) { return __kmem_cache_alloc_lru(cachep, NULL, flags); } EXPORT_SYMBOL(kmem_cache_alloc); void *kmem_cache_alloc_lru(struct kmem_cache *cachep, struct list_lru *lru, gfp_t flags) { return __kmem_cache_alloc_lru(cachep, lru, flags); } EXPORT_SYMBOL(kmem_cache_alloc_lru); static __always_inline void cache_alloc_debugcheck_after_bulk(struct kmem_cache *s, gfp_t flags, size_t size, void **p, unsigned long caller) { size_t i; for (i = 0; i < size; i++) p[i] = cache_alloc_debugcheck_after(s, flags, p[i], caller); } int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, void **p) { size_t i; struct obj_cgroup *objcg = NULL; s = slab_pre_alloc_hook(s, NULL, &objcg, size, flags); if (!s) return 0; local_irq_disable(); for (i = 0; i < size; i++) { void *objp = kfence_alloc(s, s->object_size, flags) ?: __do_cache_alloc(s, flags, NUMA_NO_NODE); if (unlikely(!objp)) goto error; p[i] = objp; } local_irq_enable(); cache_alloc_debugcheck_after_bulk(s, flags, size, p, _RET_IP_); /* * memcg and kmem_cache debug support and memory initialization. * Done outside of the IRQ disabled section. */ slab_post_alloc_hook(s, objcg, flags, size, p, slab_want_init_on_alloc(flags, s)); /* FIXME: Trace call missing. Christoph would like a bulk variant */ return size; error: local_irq_enable(); cache_alloc_debugcheck_after_bulk(s, flags, i, p, _RET_IP_); slab_post_alloc_hook(s, objcg, flags, i, p, false); kmem_cache_free_bulk(s, i, p); return 0; } EXPORT_SYMBOL(kmem_cache_alloc_bulk); #ifdef CONFIG_TRACING void * kmem_cache_alloc_trace(struct kmem_cache *cachep, gfp_t flags, size_t size) { void *ret; ret = slab_alloc(cachep, NULL, flags, size, _RET_IP_); ret = kasan_kmalloc(cachep, ret, size, flags); trace_kmalloc(_RET_IP_, ret, cachep, size, cachep->size, flags); return ret; } EXPORT_SYMBOL(kmem_cache_alloc_trace); #endif #ifdef CONFIG_NUMA /** * kmem_cache_alloc_node - Allocate an object on the specified node * @cachep: The cache to allocate from. * @flags: See kmalloc(). * @nodeid: node number of the target node. * * Identical to kmem_cache_alloc but it will allocate memory on the given * node, which can improve the performance for cpu bound structures. * * Fallback to other node is possible if __GFP_THISNODE is not set. * * Return: pointer to the new object or %NULL in case of error */ void *kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid) { void *ret = slab_alloc_node(cachep, flags, nodeid, cachep->object_size, _RET_IP_); trace_kmem_cache_alloc_node(_RET_IP_, ret, cachep, cachep->object_size, cachep->size, flags, nodeid); return ret; } EXPORT_SYMBOL(kmem_cache_alloc_node); #ifdef CONFIG_TRACING void *kmem_cache_alloc_node_trace(struct kmem_cache *cachep, gfp_t flags, int nodeid, size_t size) { void *ret; ret = slab_alloc_node(cachep, flags, nodeid, size, _RET_IP_); ret = kasan_kmalloc(cachep, ret, size, flags); trace_kmalloc_node(_RET_IP_, ret, cachep, size, cachep->size, flags, nodeid); return ret; } EXPORT_SYMBOL(kmem_cache_alloc_node_trace); #endif static __always_inline void * __do_kmalloc_node(size_t size, gfp_t flags, int node, unsigned long caller) { struct kmem_cache *cachep; void *ret; if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) return NULL; cachep = kmalloc_slab(size, flags); if (unlikely(ZERO_OR_NULL_PTR(cachep))) return cachep; ret = kmem_cache_alloc_node_trace(cachep, flags, node, size); ret = kasan_kmalloc(cachep, ret, size, flags); return ret; } void *__kmalloc_node(size_t size, gfp_t flags, int node) { return __do_kmalloc_node(size, flags, node, _RET_IP_); } EXPORT_SYMBOL(__kmalloc_node); void *__kmalloc_node_track_caller(size_t size, gfp_t flags, int node, unsigned long caller) { return __do_kmalloc_node(size, flags, node, caller); } EXPORT_SYMBOL(__kmalloc_node_track_caller); #endif /* CONFIG_NUMA */ #ifdef CONFIG_PRINTK void __kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab) { struct kmem_cache *cachep; unsigned int objnr; void *objp; kpp->kp_ptr = object; kpp->kp_slab = slab; cachep = slab->slab_cache; kpp->kp_slab_cache = cachep; objp = object - obj_offset(cachep); kpp->kp_data_offset = obj_offset(cachep); slab = virt_to_slab(objp); objnr = obj_to_index(cachep, slab, objp); objp = index_to_obj(cachep, slab, objnr); kpp->kp_objp = objp; if (DEBUG && cachep->flags & SLAB_STORE_USER) kpp->kp_ret = *dbg_userword(cachep, objp); } #endif /** * __do_kmalloc - allocate memory * @size: how many bytes of memory are required. * @flags: the type of memory to allocate (see kmalloc). * @caller: function caller for debug tracking of the caller * * Return: pointer to the allocated memory or %NULL in case of error */ static __always_inline void *__do_kmalloc(size_t size, gfp_t flags, unsigned long caller) { struct kmem_cache *cachep; void *ret; if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) return NULL; cachep = kmalloc_slab(size, flags); if (unlikely(ZERO_OR_NULL_PTR(cachep))) return cachep; ret = slab_alloc(cachep, NULL, flags, size, caller); ret = kasan_kmalloc(cachep, ret, size, flags); trace_kmalloc(caller, ret, cachep, size, cachep->size, flags); return ret; } void *__kmalloc(size_t size, gfp_t flags) { return __do_kmalloc(size, flags, _RET_IP_); } EXPORT_SYMBOL(__kmalloc); void *__kmalloc_track_caller(size_t size, gfp_t flags, unsigned long caller) { return __do_kmalloc(size, flags, caller); } EXPORT_SYMBOL(__kmalloc_track_caller); /** * kmem_cache_free - Deallocate an object * @cachep: The cache the allocation was from. * @objp: The previously allocated object. * * Free an object which was previously allocated from this * cache. */ void kmem_cache_free(struct kmem_cache *cachep, void *objp) { unsigned long flags; cachep = cache_from_obj(cachep, objp); if (!cachep) return; trace_kmem_cache_free(_RET_IP_, objp, cachep->name); local_irq_save(flags); debug_check_no_locks_freed(objp, cachep->object_size); if (!(cachep->flags & SLAB_DEBUG_OBJECTS)) debug_check_no_obj_freed(objp, cachep->object_size); __cache_free(cachep, objp, _RET_IP_); local_irq_restore(flags); } EXPORT_SYMBOL(kmem_cache_free); void kmem_cache_free_bulk(struct kmem_cache *orig_s, size_t size, void **p) { struct kmem_cache *s; size_t i; local_irq_disable(); for (i = 0; i < size; i++) { void *objp = p[i]; if (!orig_s) /* called via kfree_bulk */ s = virt_to_cache(objp); else s = cache_from_obj(orig_s, objp); if (!s) continue; debug_check_no_locks_freed(objp, s->object_size); if (!(s->flags & SLAB_DEBUG_OBJECTS)) debug_check_no_obj_freed(objp, s->object_size); __cache_free(s, objp, _RET_IP_); } local_irq_enable(); /* FIXME: add tracing */ } EXPORT_SYMBOL(kmem_cache_free_bulk); /** * kfree - free previously allocated memory * @objp: pointer returned by kmalloc. * * If @objp is NULL, no operation is performed. * * Don't free memory not originally allocated by kmalloc() * or you will run into trouble. */ void kfree(const void *objp) { struct kmem_cache *c; unsigned long flags; trace_kfree(_RET_IP_, objp); if (unlikely(ZERO_OR_NULL_PTR(objp))) return; local_irq_save(flags); kfree_debugcheck(objp); c = virt_to_cache(objp); if (!c) { local_irq_restore(flags); return; } debug_check_no_locks_freed(objp, c->object_size); debug_check_no_obj_freed(objp, c->object_size); __cache_free(c, (void *)objp, _RET_IP_); local_irq_restore(flags); } EXPORT_SYMBOL(kfree); /* * This initializes kmem_cache_node or resizes various caches for all nodes. */ static int setup_kmem_cache_nodes(struct kmem_cache *cachep, gfp_t gfp) { int ret; int node; struct kmem_cache_node *n; for_each_online_node(node) { ret = setup_kmem_cache_node(cachep, node, gfp, true); if (ret) goto fail; } return 0; fail: if (!cachep->list.next) { /* Cache is not active yet. Roll back what we did */ node--; while (node >= 0) { n = get_node(cachep, node); if (n) { kfree(n->shared); free_alien_cache(n->alien); kfree(n); cachep->node[node] = NULL; } node--; } } return -ENOMEM; } /* Always called with the slab_mutex held */ static int do_tune_cpucache(struct kmem_cache *cachep, int limit, int batchcount, int shared, gfp_t gfp) { struct array_cache __percpu *cpu_cache, *prev; int cpu; cpu_cache = alloc_kmem_cache_cpus(cachep, limit, batchcount); if (!cpu_cache) return -ENOMEM; prev = cachep->cpu_cache; cachep->cpu_cache = cpu_cache; /* * Without a previous cpu_cache there's no need to synchronize remote * cpus, so skip the IPIs. */ if (prev) kick_all_cpus_sync(); check_irq_on(); cachep->batchcount = batchcount; cachep->limit = limit; cachep->shared = shared; if (!prev) goto setup_node; for_each_online_cpu(cpu) { LIST_HEAD(list); int node; struct kmem_cache_node *n; struct array_cache *ac = per_cpu_ptr(prev, cpu); node = cpu_to_mem(cpu); n = get_node(cachep, node); spin_lock_irq(&n->list_lock); free_block(cachep, ac->entry, ac->avail, node, &list); spin_unlock_irq(&n->list_lock); slabs_destroy(cachep, &list); } free_percpu(prev); setup_node: return setup_kmem_cache_nodes(cachep, gfp); } /* Called with slab_mutex held always */ static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp) { int err; int limit = 0; int shared = 0; int batchcount = 0; err = cache_random_seq_create(cachep, cachep->num, gfp); if (err) goto end; /* * The head array serves three purposes: * - create a LIFO ordering, i.e. return objects that are cache-warm * - reduce the number of spinlock operations. * - reduce the number of linked list operations on the slab and * bufctl chains: array operations are cheaper. * The numbers are guessed, we should auto-tune as described by * Bonwick. */ if (cachep->size > 131072) limit = 1; else if (cachep->size > PAGE_SIZE) limit = 8; else if (cachep->size > 1024) limit = 24; else if (cachep->size > 256) limit = 54; else limit = 120; /* * CPU bound tasks (e.g. network routing) can exhibit cpu bound * allocation behaviour: Most allocs on one cpu, most free operations * on another cpu. For these cases, an efficient object passing between * cpus is necessary. This is provided by a shared array. The array * replaces Bonwick's magazine layer. * On uniprocessor, it's functionally equivalent (but less efficient) * to a larger limit. Thus disabled by default. */ shared = 0; if (cachep->size <= PAGE_SIZE && num_possible_cpus() > 1) shared = 8; #if DEBUG /* * With debugging enabled, large batchcount lead to excessively long * periods with disabled local interrupts. Limit the batchcount */ if (limit > 32) limit = 32; #endif batchcount = (limit + 1) / 2; err = do_tune_cpucache(cachep, limit, batchcount, shared, gfp); end: if (err) pr_err("enable_cpucache failed for %s, error %d\n", cachep->name, -err); return err; } /* * Drain an array if it contains any elements taking the node lock only if * necessary. Note that the node listlock also protects the array_cache * if drain_array() is used on the shared array. */ static void drain_array(struct kmem_cache *cachep, struct kmem_cache_node *n, struct array_cache *ac, int node) { LIST_HEAD(list); /* ac from n->shared can be freed if we don't hold the slab_mutex. */ check_mutex_acquired(); if (!ac || !ac->avail) return; if (ac->touched) { ac->touched = 0; return; } spin_lock_irq(&n->list_lock); drain_array_locked(cachep, ac, node, false, &list); spin_unlock_irq(&n->list_lock); slabs_destroy(cachep, &list); } /** * cache_reap - Reclaim memory from caches. * @w: work descriptor * * Called from workqueue/eventd every few seconds. * Purpose: * - clear the per-cpu caches for this CPU. * - return freeable pages to the main free memory pool. * * If we cannot acquire the cache chain mutex then just give up - we'll try * again on the next iteration. */ static void cache_reap(struct work_struct *w) { struct kmem_cache *searchp; struct kmem_cache_node *n; int node = numa_mem_id(); struct delayed_work *work = to_delayed_work(w); if (!mutex_trylock(&slab_mutex)) /* Give up. Setup the next iteration. */ goto out; list_for_each_entry(searchp, &slab_caches, list) { check_irq_on(); /* * We only take the node lock if absolutely necessary and we * have established with reasonable certainty that * we can do some work if the lock was obtained. */ n = get_node(searchp, node); reap_alien(searchp, n); drain_array(searchp, n, cpu_cache_get(searchp), node); /* * These are racy checks but it does not matter * if we skip one check or scan twice. */ if (time_after(n->next_reap, jiffies)) goto next; n->next_reap = jiffies + REAPTIMEOUT_NODE; drain_array(searchp, n, n->shared, node); if (n->free_touched) n->free_touched = 0; else { int freed; freed = drain_freelist(searchp, n, (n->free_limit + 5 * searchp->num - 1) / (5 * searchp->num)); STATS_ADD_REAPED(searchp, freed); } next: cond_resched(); } check_irq_on(); mutex_unlock(&slab_mutex); next_reap_node(); out: /* Set up the next iteration */ schedule_delayed_work_on(smp_processor_id(), work, round_jiffies_relative(REAPTIMEOUT_AC)); } void get_slabinfo(struct kmem_cache *cachep, struct slabinfo *sinfo) { unsigned long active_objs, num_objs, active_slabs; unsigned long total_slabs = 0, free_objs = 0, shared_avail = 0; unsigned long free_slabs = 0; int node; struct kmem_cache_node *n; for_each_kmem_cache_node(cachep, node, n) { check_irq_on(); spin_lock_irq(&n->list_lock); total_slabs += n->total_slabs; free_slabs += n->free_slabs; free_objs += n->free_objects; if (n->shared) shared_avail += n->shared->avail; spin_unlock_irq(&n->list_lock); } num_objs = total_slabs * cachep->num; active_slabs = total_slabs - free_slabs; active_objs = num_objs - free_objs; sinfo->active_objs = active_objs; sinfo->num_objs = num_objs; sinfo->active_slabs = active_slabs; sinfo->num_slabs = total_slabs; sinfo->shared_avail = shared_avail; sinfo->limit = cachep->limit; sinfo->batchcount = cachep->batchcount; sinfo->shared = cachep->shared; sinfo->objects_per_slab = cachep->num; sinfo->cache_order = cachep->gfporder; } void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *cachep) { #if STATS { /* node stats */ unsigned long high = cachep->high_mark; unsigned long allocs = cachep->num_allocations; unsigned long grown = cachep->grown; unsigned long reaped = cachep->reaped; unsigned long errors = cachep->errors; unsigned long max_freeable = cachep->max_freeable; unsigned long node_allocs = cachep->node_allocs; unsigned long node_frees = cachep->node_frees; unsigned long overflows = cachep->node_overflow; seq_printf(m, " : globalstat %7lu %6lu %5lu %4lu %4lu %4lu %4lu %4lu %4lu", allocs, high, grown, reaped, errors, max_freeable, node_allocs, node_frees, overflows); } /* cpu stats */ { unsigned long allochit = atomic_read(&cachep->allochit); unsigned long allocmiss = atomic_read(&cachep->allocmiss); unsigned long freehit = atomic_read(&cachep->freehit); unsigned long freemiss = atomic_read(&cachep->freemiss); seq_printf(m, " : cpustat %6lu %6lu %6lu %6lu", allochit, allocmiss, freehit, freemiss); } #endif } #define MAX_SLABINFO_WRITE 128 /** * slabinfo_write - Tuning for the slab allocator * @file: unused * @buffer: user buffer * @count: data length * @ppos: unused * * Return: %0 on success, negative error code otherwise. */ ssize_t slabinfo_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos) { char kbuf[MAX_SLABINFO_WRITE + 1], *tmp; int limit, batchcount, shared, res; struct kmem_cache *cachep; if (count > MAX_SLABINFO_WRITE) return -EINVAL; if (copy_from_user(&kbuf, buffer, count)) return -EFAULT; kbuf[MAX_SLABINFO_WRITE] = '\0'; tmp = strchr(kbuf, ' '); if (!tmp) return -EINVAL; *tmp = '\0'; tmp++; if (sscanf(tmp, " %d %d %d", &limit, &batchcount, &shared) != 3) return -EINVAL; /* Find the cache in the chain of caches. */ mutex_lock(&slab_mutex); res = -EINVAL; list_for_each_entry(cachep, &slab_caches, list) { if (!strcmp(cachep->name, kbuf)) { if (limit < 1 || batchcount < 1 || batchcount > limit || shared < 0) { res = 0; } else { res = do_tune_cpucache(cachep, limit, batchcount, shared, GFP_KERNEL); } break; } } mutex_unlock(&slab_mutex); if (res >= 0) res = count; return res; } #ifdef CONFIG_HARDENED_USERCOPY /* * Rejects incorrectly sized objects and objects that are to be copied * to/from userspace but do not fall entirely within the containing slab * cache's usercopy region. * * Returns NULL if check passes, otherwise const char * to name of cache * to indicate an error. */ void __check_heap_object(const void *ptr, unsigned long n, const struct slab *slab, bool to_user) { struct kmem_cache *cachep; unsigned int objnr; unsigned long offset; ptr = kasan_reset_tag(ptr); /* Find and validate object. */ cachep = slab->slab_cache; objnr = obj_to_index(cachep, slab, (void *)ptr); BUG_ON(objnr >= cachep->num); /* Find offset within object. */ if (is_kfence_address(ptr)) offset = ptr - kfence_object_start(ptr); else offset = ptr - index_to_obj(cachep, slab, objnr) - obj_offset(cachep); /* Allow address range falling entirely within usercopy region. */ if (offset >= cachep->useroffset && offset - cachep->useroffset <= cachep->usersize && n <= cachep->useroffset - offset + cachep->usersize) return; usercopy_abort("SLAB object", cachep->name, to_user, offset, n); } #endif /* CONFIG_HARDENED_USERCOPY */ /** * __ksize -- Uninstrumented ksize. * @objp: pointer to the object * * Unlike ksize(), __ksize() is uninstrumented, and does not provide the same * safety checks as ksize() with KASAN instrumentation enabled. * * Return: size of the actual memory used by @objp in bytes */ size_t __ksize(const void *objp) { struct kmem_cache *c; size_t size; BUG_ON(!objp); if (unlikely(objp == ZERO_SIZE_PTR)) return 0; c = virt_to_cache(objp); size = c ? c->object_size : 0; return size; } EXPORT_SYMBOL(__ksize);