/* * 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 <shai@scalex86.org>. * Shobhit Dayal <shobhit@calsoftinc.com> * Alok N Kataria <alokk@calsoftinc.com> * Christoph Lameter <christoph@lameter.com> * * 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 <linux/slab.h> #include <linux/mm.h> #include <linux/poison.h> #include <linux/swap.h> #include <linux/cache.h> #include <linux/interrupt.h> #include <linux/init.h> #include <linux/compiler.h> #include <linux/cpuset.h> #include <linux/proc_fs.h> #include <linux/seq_file.h> #include <linux/notifier.h> #include <linux/kallsyms.h> #include <linux/cpu.h> #include <linux/sysctl.h> #include <linux/module.h> #include <linux/rcupdate.h> #include <linux/string.h> #include <linux/uaccess.h> #include <linux/nodemask.h> #include <linux/kmemleak.h> #include <linux/mempolicy.h> #include <linux/mutex.h> #include <linux/fault-inject.h> #include <linux/rtmutex.h> #include <linux/reciprocal_div.h> #include <linux/debugobjects.h> #include <linux/kmemcheck.h> #include <linux/memory.h> #include <linux/prefetch.h> #include <net/sock.h> #include <asm/cacheflush.h> #include <asm/tlbflush.h> #include <asm/page.h> #include <trace/events/kmem.h> #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) /* * true if a page was allocated from pfmemalloc reserves for network-based * swap */ static bool pfmemalloc_active __read_mostly; /* * 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. * * Entries should not be directly dereferenced as * entries belonging to slabs marked pfmemalloc will * have the lower bits set SLAB_OBJ_PFMEMALLOC */ }; struct alien_cache { spinlock_t lock; struct array_cache ac; }; #define SLAB_OBJ_PFMEMALLOC 1 static inline bool is_obj_pfmemalloc(void *objp) { return (unsigned long)objp & SLAB_OBJ_PFMEMALLOC; } static inline void set_obj_pfmemalloc(void **objp) { *objp = (void *)((unsigned long)*objp | SLAB_OBJ_PFMEMALLOC); return; } static inline void clear_obj_pfmemalloc(void **objp) { *objp = (void *)((unsigned long)*objp & ~SLAB_OBJ_PFMEMALLOC); } /* * bootstrap: The caches do not work without cpuarrays anymore, but the * cpuarrays are allocated from the generic caches... */ #define BOOT_CPUCACHE_ENTRIES 1 struct arraycache_init { struct array_cache cache; void *entries[BOOT_CPUCACHE_ENTRIES]; }; /* * 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 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->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_OFF_SLAB (0x80000000UL) #define OFF_SLAB(x) ((x)->flags & CFLGS_OFF_SLAB) #define BATCHREFILL_LIMIT 16 /* * Optimization question: fewer reaps means less probability for unnessary * 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 #define OBJECT_FREE (0) #define OBJECT_ACTIVE (1) #ifdef CONFIG_DEBUG_SLAB_LEAK static void set_obj_status(struct page *page, int idx, int val) { int freelist_size; char *status; struct kmem_cache *cachep = page->slab_cache; freelist_size = cachep->num * sizeof(freelist_idx_t); status = (char *)page->freelist + freelist_size; status[idx] = val; } static inline unsigned int get_obj_status(struct page *page, int idx) { int freelist_size; char *status; struct kmem_cache *cachep = page->slab_cache; freelist_size = cachep->num * sizeof(freelist_idx_t); status = (char *)page->freelist + freelist_size; return status[idx]; } #else static inline void set_obj_status(struct page *page, int idx, int val) {} #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 struct kmem_cache *virt_to_cache(const void *obj) { struct page *page = virt_to_head_page(obj); return page->slab_cache; } static inline void *index_to_obj(struct kmem_cache *cache, struct page *page, unsigned int idx) { return page->s_mem + cache->size * idx; } /* * We want to avoid an expensive divide : (offset / cache->size) * Using the fact that size is a constant for a particular cache, * we can replace (offset / cache->size) by * reciprocal_divide(offset, cache->reciprocal_buffer_size) */ static inline unsigned int obj_to_index(const struct kmem_cache *cache, const struct page *page, void *obj) { u32 offset = (obj - page->s_mem); return reciprocal_divide(offset, cache->reciprocal_buffer_size); } /* 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", }; #define BAD_ALIEN_MAGIC 0x01020304ul 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); } static size_t calculate_freelist_size(int nr_objs, size_t align) { size_t freelist_size; freelist_size = nr_objs * sizeof(freelist_idx_t); if (IS_ENABLED(CONFIG_DEBUG_SLAB_LEAK)) freelist_size += nr_objs * sizeof(char); if (align) freelist_size = ALIGN(freelist_size, align); return freelist_size; } static int calculate_nr_objs(size_t slab_size, size_t buffer_size, size_t idx_size, size_t align) { int nr_objs; size_t remained_size; size_t freelist_size; int extra_space = 0; if (IS_ENABLED(CONFIG_DEBUG_SLAB_LEAK)) extra_space = sizeof(char); /* * Ignore padding for the initial guess. The padding * is at most @align-1 bytes, and @buffer_size is at * least @align. In the worst case, this result will * be one greater than the number of objects that fit * into the memory allocation when taking the padding * into account. */ nr_objs = slab_size / (buffer_size + idx_size + extra_space); /* * This calculated number will be either the right * amount, or one greater than what we want. */ remained_size = slab_size - nr_objs * buffer_size; freelist_size = calculate_freelist_size(nr_objs, align); if (remained_size < freelist_size) nr_objs--; return nr_objs; } /* * Calculate the number of objects and left-over bytes for a given buffer size. */ static void cache_estimate(unsigned long gfporder, size_t buffer_size, size_t align, int flags, size_t *left_over, unsigned int *num) { int nr_objs; size_t mgmt_size; 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: * * - One unsigned int for each object * - Padding to respect alignment of @align * - @buffer_size bytes for each object * * 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_OFF_SLAB) { mgmt_size = 0; nr_objs = slab_size / buffer_size; } else { nr_objs = calculate_nr_objs(slab_size, buffer_size, sizeof(freelist_idx_t), align); mgmt_size = calculate_freelist_size(nr_objs, align); } *num = nr_objs; *left_over = slab_size - nr_objs*buffer_size - mgmt_size; } #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) { printk(KERN_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) { int node; node = next_node(cpu_to_mem(cpu), node_online_map); if (node == MAX_NUMNODES) node = first_node(node_online_map); per_cpu(slab_reap_node, cpu) = node; } static void next_reap_node(void) { int node = __this_cpu_read(slab_reap_node); node = next_node(node, node_online_map); if (unlikely(node >= MAX_NUMNODES)) node = first_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); /* * When this gets called from do_initcalls via cpucache_init(), * init_workqueues() has already run, so keventd will be setup * at that time. */ if (keventd_up() && 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) { /* * 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); 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); init_arraycache(ac, entries, batchcount); return ac; } static inline bool is_slab_pfmemalloc(struct page *page) { return PageSlabPfmemalloc(page); } /* Clears pfmemalloc_active if no slabs have pfmalloc set */ static void recheck_pfmemalloc_active(struct kmem_cache *cachep, struct array_cache *ac) { struct kmem_cache_node *n = get_node(cachep, numa_mem_id()); struct page *page; unsigned long flags; if (!pfmemalloc_active) return; spin_lock_irqsave(&n->list_lock, flags); list_for_each_entry(page, &n->slabs_full, lru) if (is_slab_pfmemalloc(page)) goto out; list_for_each_entry(page, &n->slabs_partial, lru) if (is_slab_pfmemalloc(page)) goto out; list_for_each_entry(page, &n->slabs_free, lru) if (is_slab_pfmemalloc(page)) goto out; pfmemalloc_active = false; out: spin_unlock_irqrestore(&n->list_lock, flags); } static void *__ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac, gfp_t flags, bool force_refill) { int i; void *objp = ac->entry[--ac->avail]; /* Ensure the caller is allowed to use objects from PFMEMALLOC slab */ if (unlikely(is_obj_pfmemalloc(objp))) { struct kmem_cache_node *n; if (gfp_pfmemalloc_allowed(flags)) { clear_obj_pfmemalloc(&objp); return objp; } /* The caller cannot use PFMEMALLOC objects, find another one */ for (i = 0; i < ac->avail; i++) { /* If a !PFMEMALLOC object is found, swap them */ if (!is_obj_pfmemalloc(ac->entry[i])) { objp = ac->entry[i]; ac->entry[i] = ac->entry[ac->avail]; ac->entry[ac->avail] = objp; return objp; } } /* * If there are empty slabs on the slabs_free list and we are * being forced to refill the cache, mark this one !pfmemalloc. */ n = get_node(cachep, numa_mem_id()); if (!list_empty(&n->slabs_free) && force_refill) { struct page *page = virt_to_head_page(objp); ClearPageSlabPfmemalloc(page); clear_obj_pfmemalloc(&objp); recheck_pfmemalloc_active(cachep, ac); return objp; } /* No !PFMEMALLOC objects available */ ac->avail++; objp = NULL; } return objp; } static inline void *ac_get_obj(struct kmem_cache *cachep, struct array_cache *ac, gfp_t flags, bool force_refill) { void *objp; if (unlikely(sk_memalloc_socks())) objp = __ac_get_obj(cachep, ac, flags, force_refill); else objp = ac->entry[--ac->avail]; return objp; } static noinline void *__ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac, void *objp) { if (unlikely(pfmemalloc_active)) { /* Some pfmemalloc slabs exist, check if this is one */ struct page *page = virt_to_head_page(objp); if (PageSlabPfmemalloc(page)) set_obj_pfmemalloc(&objp); } return objp; } static inline void ac_put_obj(struct kmem_cache *cachep, struct array_cache *ac, void *objp) { if (unlikely(sk_memalloc_socks())) objp = __ac_put_obj(cachep, ac, objp); ac->entry[ac->avail++] = objp; } /* * 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; } #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 (struct alien_cache **)BAD_ALIEN_MAGIC; } 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 void *alternate_node_alloc(struct kmem_cache *cachep, gfp_t flags) { return NULL; } static inline void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid) { return NULL; } #else /* CONFIG_NUMA */ static void *____cache_alloc_node(struct kmem_cache *, gfp_t, int); static void *alternate_node_alloc(struct kmem_cache *, gfp_t); 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); 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; size_t memsize = sizeof(void *) * nr_node_ids; int i; if (limit > 1) limit = 12; alc_ptr = kzalloc_node(memsize, 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 page_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[page_node]) { alien = n->alien[page_node]; ac = &alien->ac; spin_lock(&alien->lock); if (unlikely(ac->avail == ac->limit)) { STATS_INC_ACOVERFLOW(cachep); __drain_alien_cache(cachep, ac, page_node, &list); } ac_put_obj(cachep, ac, objp); spin_unlock(&alien->lock); slabs_destroy(cachep, &list); } else { n = get_node(cachep, page_node); spin_lock(&n->list_lock); free_block(cachep, &objp, 1, page_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 page_node = page_to_nid(virt_to_page(objp)); int node = numa_mem_id(); /* * Make sure we are not freeing a object from another node to the array * cache on this cpu. */ if (likely(node == page_node)) return 0; return __cache_free_alien(cachep, objp, node, page_node); } #endif /* * 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 node are not replaced if * already in use. * * Must hold slab_mutex. */ static int init_cache_node_node(int node) { struct kmem_cache *cachep; struct kmem_cache_node *n; const size_t memsize = sizeof(struct kmem_cache_node); list_for_each_entry(cachep, &slab_caches, list) { /* * 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) { n = kmalloc_node(memsize, GFP_KERNEL, node); if (!n) return -ENOMEM; kmem_cache_node_init(n); n->next_reap = jiffies + REAPTIMEOUT_NODE + ((unsigned long)cachep) % REAPTIMEOUT_NODE; /* * The kmem_cache_nodes don't come and go as CPUs * come and go. slab_mutex is sufficient * protection here. */ cachep->node[node] = 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; } static inline int slabs_tofree(struct kmem_cache *cachep, struct kmem_cache_node *n) { return (n->free_objects + cachep->num - 1) / cachep->num; } 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); if (nc) { 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, slabs_tofree(cachep, n)); } } static int cpuup_prepare(long cpu) { struct kmem_cache *cachep; struct kmem_cache_node *n = NULL; 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) { struct array_cache *shared = NULL; struct alien_cache **alien = NULL; if (cachep->shared) { shared = alloc_arraycache(node, cachep->shared * cachep->batchcount, 0xbaadf00d, GFP_KERNEL); if (!shared) goto bad; } if (use_alien_caches) { alien = alloc_alien_cache(node, cachep->limit, GFP_KERNEL); if (!alien) { kfree(shared); goto bad; } } n = get_node(cachep, node); BUG_ON(!n); spin_lock_irq(&n->list_lock); if (!n->shared) { /* * We are serialised from CPU_DEAD or * CPU_UP_CANCELLED by the cpucontrol lock */ n->shared = shared; shared = NULL; } #ifdef CONFIG_NUMA if (!n->alien) { n->alien = alien; alien = NULL; } #endif spin_unlock_irq(&n->list_lock); kfree(shared); free_alien_cache(alien); } return 0; bad: cpuup_canceled(cpu); return -ENOMEM; } static int cpuup_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) { long cpu = (long)hcpu; int err = 0; switch (action) { case CPU_UP_PREPARE: case CPU_UP_PREPARE_FROZEN: mutex_lock(&slab_mutex); err = cpuup_prepare(cpu); mutex_unlock(&slab_mutex); break; case CPU_ONLINE: case CPU_ONLINE_FROZEN: start_cpu_timer(cpu); break; #ifdef CONFIG_HOTPLUG_CPU case CPU_DOWN_PREPARE: case CPU_DOWN_PREPARE_FROZEN: /* * 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; break; case CPU_DOWN_FAILED: case CPU_DOWN_FAILED_FROZEN: start_cpu_timer(cpu); break; case CPU_DEAD: case CPU_DEAD_FROZEN: /* * Even if all the cpus of a node are down, we don't free the * kmem_cache_node of any cache. This 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 node * structure is usually allocated from kmem_cache_create() and * gets destroyed at kmem_cache_destroy(). */ /* fall through */ #endif case CPU_UP_CANCELED: case CPU_UP_CANCELED_FROZEN: mutex_lock(&slab_mutex); cpuup_canceled(cpu); mutex_unlock(&slab_mutex); break; } return notifier_from_errno(err); } static struct notifier_block cpucache_notifier = { &cpuup_callback, NULL, 0 }; #if defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG) /* * 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, slabs_tofree(cachep, n)); 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 && CONFIG_MEMORY_HOTPLUG */ /* * 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; BUILD_BUG_ON(sizeof(((struct page *)NULL)->lru) < sizeof(struct rcu_head)); kmem_cache = &kmem_cache_boot; if (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); 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[INDEX_NODE] = create_kmalloc_cache("kmalloc-node", kmalloc_size(INDEX_NODE), ARCH_KMALLOC_FLAGS); slab_state = PARTIAL_NODE; 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[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; slab_state = UP; /* 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; /* * Register a cpu startup notifier callback that initializes * cpu_cache_get for all new cpus */ register_cpu_notifier(&cpucache_notifier); #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 cpu; /* * Register the timers that return unneeded pages to the page allocator */ for_each_online_cpu(cpu) start_cpu_timer(cpu); /* Done! */ slab_state = FULL; 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; struct page *page; 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; printk(KERN_WARNING "SLAB: Unable to allocate memory on node %d (gfp=0x%x)\n", nodeid, gfpflags); printk(KERN_WARNING " cache: %s, object size: %d, order: %d\n", cachep->name, cachep->size, cachep->gfporder); for_each_kmem_cache_node(cachep, node, n) { unsigned long active_objs = 0, num_objs = 0, free_objects = 0; unsigned long active_slabs = 0, num_slabs = 0; spin_lock_irqsave(&n->list_lock, flags); list_for_each_entry(page, &n->slabs_full, lru) { active_objs += cachep->num; active_slabs++; } list_for_each_entry(page, &n->slabs_partial, lru) { active_objs += page->active; active_slabs++; } list_for_each_entry(page, &n->slabs_free, lru) num_slabs++; free_objects += n->free_objects; spin_unlock_irqrestore(&n->list_lock, flags); num_slabs += active_slabs; num_objs = num_slabs * cachep->num; printk(KERN_WARNING " node %d: slabs: %ld/%ld, objs: %ld/%ld, free: %ld\n", node, active_slabs, num_slabs, active_objs, num_objs, free_objects); } #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 page *kmem_getpages(struct kmem_cache *cachep, gfp_t flags, int nodeid) { struct page *page; int nr_pages; flags |= cachep->allocflags; if (cachep->flags & SLAB_RECLAIM_ACCOUNT) flags |= __GFP_RECLAIMABLE; if (memcg_charge_slab(cachep, flags, cachep->gfporder)) return NULL; page = alloc_pages_exact_node(nodeid, flags | __GFP_NOTRACK, cachep->gfporder); if (!page) { memcg_uncharge_slab(cachep, cachep->gfporder); slab_out_of_memory(cachep, flags, nodeid); return NULL; } /* Record if ALLOC_NO_WATERMARKS was set when allocating the slab */ if (unlikely(page->pfmemalloc)) pfmemalloc_active = true; nr_pages = (1 << cachep->gfporder); if (cachep->flags & SLAB_RECLAIM_ACCOUNT) add_zone_page_state(page_zone(page), NR_SLAB_RECLAIMABLE, nr_pages); else add_zone_page_state(page_zone(page), NR_SLAB_UNRECLAIMABLE, nr_pages); __SetPageSlab(page); if (page->pfmemalloc) SetPageSlabPfmemalloc(page); if (kmemcheck_enabled && !(cachep->flags & SLAB_NOTRACK)) { kmemcheck_alloc_shadow(page, cachep->gfporder, flags, nodeid); if (cachep->ctor) kmemcheck_mark_uninitialized_pages(page, nr_pages); else kmemcheck_mark_unallocated_pages(page, nr_pages); } return page; } /* * Interface to system's page release. */ static void kmem_freepages(struct kmem_cache *cachep, struct page *page) { const unsigned long nr_freed = (1 << cachep->gfporder); kmemcheck_free_shadow(page, cachep->gfporder); if (cachep->flags & SLAB_RECLAIM_ACCOUNT) sub_zone_page_state(page_zone(page), NR_SLAB_RECLAIMABLE, nr_freed); else sub_zone_page_state(page_zone(page), NR_SLAB_UNRECLAIMABLE, nr_freed); BUG_ON(!PageSlab(page)); __ClearPageSlabPfmemalloc(page); __ClearPageSlab(page); page_mapcount_reset(page); page->mapping = NULL; if (current->reclaim_state) current->reclaim_state->reclaimed_slab += nr_freed; __free_pages(page, cachep->gfporder); memcg_uncharge_slab(cachep, cachep->gfporder); } static void kmem_rcu_free(struct rcu_head *head) { struct kmem_cache *cachep; struct page *page; page = container_of(head, struct page, rcu_head); cachep = page->slab_cache; kmem_freepages(cachep, page); } #if DEBUG #ifdef CONFIG_DEBUG_PAGEALLOC static void store_stackinfo(struct kmem_cache *cachep, unsigned long *addr, unsigned long caller) { int size = cachep->object_size; addr = (unsigned long *)&((char *)addr)[obj_offset(cachep)]; if (size < 5 * sizeof(unsigned long)) return; *addr++ = 0x12345678; *addr++ = caller; *addr++ = smp_processor_id(); size -= 3 * sizeof(unsigned long); { unsigned long *sptr = &caller; unsigned long svalue; while (!kstack_end(sptr)) { svalue = *sptr++; if (kernel_text_address(svalue)) { *addr++ = svalue; size -= sizeof(unsigned long); if (size <= sizeof(unsigned long)) break; } } } *addr++ = 0x87654321; } #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; printk(KERN_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))) { printk(KERN_ERR "Single bit error detected. Probably " "bad RAM.\n"); #ifdef CONFIG_X86 printk(KERN_ERR "Run memtest86+ or a similar memory " "test tool.\n"); #else printk(KERN_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) { printk(KERN_ERR "Redzone: 0x%llx/0x%llx.\n", *dbg_redzone1(cachep, objp), *dbg_redzone2(cachep, objp)); } if (cachep->flags & SLAB_STORE_USER) { printk(KERN_ERR "Last user: [<%p>](%pSR)\n", *dbg_userword(cachep, objp), *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; 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) { printk(KERN_ERR "Slab corruption (%s): %s start=%p, 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 page *page = virt_to_head_page(objp); unsigned int objnr; objnr = obj_to_index(cachep, page, objp); if (objnr) { objp = index_to_obj(cachep, page, objnr - 1); realobj = (char *)objp + obj_offset(cachep); printk(KERN_ERR "Prev obj: start=%p, len=%d\n", realobj, size); print_objinfo(cachep, objp, 2); } if (objnr + 1 < cachep->num) { objp = index_to_obj(cachep, page, objnr + 1); realobj = (char *)objp + obj_offset(cachep); printk(KERN_ERR "Next obj: start=%p, len=%d\n", realobj, size); print_objinfo(cachep, objp, 2); } } } #endif #if DEBUG static void slab_destroy_debugcheck(struct kmem_cache *cachep, struct page *page) { int i; for (i = 0; i < cachep->num; i++) { void *objp = index_to_obj(cachep, page, i); if (cachep->flags & SLAB_POISON) { #ifdef CONFIG_DEBUG_PAGEALLOC if (cachep->size % PAGE_SIZE == 0 && OFF_SLAB(cachep)) kernel_map_pages(virt_to_page(objp), cachep->size / PAGE_SIZE, 1); else check_poison_obj(cachep, objp); #else check_poison_obj(cachep, objp); #endif } 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 page *page) { } #endif /** * slab_destroy - destroy and release all objects in a slab * @cachep: cache pointer being destroyed * @page: page pointer being destroyed * * Destroy all the objs in a slab page, and release the mem back to the system. * Before calling the slab page 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 page *page) { void *freelist; freelist = page->freelist; slab_destroy_debugcheck(cachep, page); if (unlikely(cachep->flags & SLAB_DESTROY_BY_RCU)) { struct rcu_head *head; /* * RCU free overloads the RCU head over the LRU. * slab_page has been overloeaded over the LRU, * however it is not used from now on so that * we can use it safely. */ head = (void *)&page->rcu_head; call_rcu(head, kmem_rcu_free); } else { kmem_freepages(cachep, page); } /* * 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); } static void slabs_destroy(struct kmem_cache *cachep, struct list_head *list) { struct page *page, *n; list_for_each_entry_safe(page, n, list, lru) { list_del(&page->lru); slab_destroy(cachep, page); } } /** * 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. * @align: required alignment for the objects. * @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. */ static size_t calculate_slab_order(struct kmem_cache *cachep, size_t size, size_t align, unsigned long flags) { unsigned long offslab_limit; size_t left_over = 0; int gfporder; for (gfporder = 0; gfporder <= KMALLOC_MAX_ORDER; gfporder++) { unsigned int num; size_t remainder; cache_estimate(gfporder, size, align, flags, &remainder, &num); 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) { size_t freelist_size_per_obj = sizeof(freelist_idx_t); /* * Max number of objs-per-slab for caches which * use off-slab slabs. Needed to avoid a possible * looping condition in cache_grow(). */ if (IS_ENABLED(CONFIG_DEBUG_SLAB_LEAK)) freelist_size_per_obj += sizeof(char); offslab_limit = size; offslab_limit /= freelist_size_per_obj; if (num > offslab_limit) break; } /* 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 __init_refok 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; } unsigned long kmem_cache_flags(unsigned long object_size, unsigned long flags, const char *name, void (*ctor)(void *)) { return flags; } struct kmem_cache * __kmem_cache_alias(const char *name, size_t size, size_t align, unsigned long 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; } /** * __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 a 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. */ int __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags) { size_t left_over, freelist_size; size_t ralign = BYTES_PER_WORD; gfp_t gfp; int err; size_t 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_DESTROY_BY_RCU)) flags |= SLAB_POISON; #endif if (flags & SLAB_DESTROY_BY_RCU) BUG_ON(flags & SLAB_POISON); #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. */ if (size & (BYTES_PER_WORD - 1)) { size += (BYTES_PER_WORD - 1); size &= ~(BYTES_PER_WORD - 1); } 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 += REDZONE_ALIGN - 1; size &= ~(REDZONE_ALIGN - 1); } /* 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; 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; } #if FORCED_DEBUG && defined(CONFIG_DEBUG_PAGEALLOC) if (size >= kmalloc_size(INDEX_NODE + 1) && cachep->object_size > cache_line_size() && ALIGN(size, cachep->align) < PAGE_SIZE) { cachep->obj_offset += PAGE_SIZE - ALIGN(size, cachep->align); size = PAGE_SIZE; } #endif #endif /* * Determine if the slab management is 'on' or 'off' slab. * (bootstrapping cannot cope with offslab caches so don't do * it too early on. Always use on-slab management when * SLAB_NOLEAKTRACE to avoid recursive calls into kmemleak) */ if ((size >= (PAGE_SIZE >> 5)) && !slab_early_init && !(flags & SLAB_NOLEAKTRACE)) /* * Size is large, assume best to place the slab management obj * off-slab (should allow better packing of objs). */ flags |= CFLGS_OFF_SLAB; 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); left_over = calculate_slab_order(cachep, size, cachep->align, flags); if (!cachep->num) return -E2BIG; freelist_size = calculate_freelist_size(cachep->num, cachep->align); /* * 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 (flags & CFLGS_OFF_SLAB && left_over >= freelist_size) { flags &= ~CFLGS_OFF_SLAB; left_over -= freelist_size; } if (flags & CFLGS_OFF_SLAB) { /* really off slab. No need for manual alignment */ freelist_size = calculate_freelist_size(cachep->num, 0); #ifdef CONFIG_PAGE_POISONING /* 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 (size % PAGE_SIZE == 0 && flags & SLAB_POISON) flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER); #endif } 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; cachep->colour = left_over / cachep->colour_off; cachep->freelist_size = freelist_size; cachep->flags = flags; cachep->allocflags = __GFP_COMP; if (CONFIG_ZONE_DMA_FLAG && (flags & SLAB_CACHE_DMA)) cachep->allocflags |= GFP_DMA; cachep->size = size; cachep->reciprocal_buffer_size = reciprocal_value(size); if (flags & CFLGS_OFF_SLAB) { cachep->freelist_cache = kmalloc_slab(freelist_size, 0u); /* * This is a possibility for one of the kmalloc_{dma,}_caches. * But since we go off slab only for object size greater than * PAGE_SIZE/8, and kmalloc_{dma,}_caches get created * in ascending order,this should not happen at all. * But leave a BUG_ON for some lucky dude. */ BUG_ON(ZERO_OR_NULL_PTR(cachep->freelist_cache)); } err = setup_cpu_cache(cachep, gfp); if (err) { __kmem_cache_shutdown(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_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_spinlock_acquired(x) do { } while(0) #define check_spinlock_acquired_node(x, y) do { } while(0) #endif static void drain_array(struct kmem_cache *cachep, struct kmem_cache_node *n, struct array_cache *ac, int force, int node); 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); slabs_destroy(cachep, &list); ac->avail = 0; } static void drain_cpu_caches(struct kmem_cache *cachep) { struct kmem_cache_node *n; int node; 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) drain_array(cachep, n, n->shared, 1, node); } /* * 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 page *page; 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; } page = list_entry(p, struct page, lru); #if DEBUG BUG_ON(page->active); #endif list_del(&page->lru); /* * 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, page); nr_freed++; } out: return nr_freed; } 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, slabs_tofree(cachep, n)); ret += !list_empty(&n->slabs_full) || !list_empty(&n->slabs_partial); } return (ret ? 1 : 0); } int __kmem_cache_shutdown(struct kmem_cache *cachep) { int i; struct kmem_cache_node *n; int rc = __kmem_cache_shrink(cachep); if (rc) return rc; 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; } return 0; } /* * 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 disired-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 page *page, int colour_off, gfp_t local_flags, int nodeid) { void *freelist; void *addr = page_address(page); if (OFF_SLAB(cachep)) { /* Slab management obj is off-slab. */ freelist = kmem_cache_alloc_node(cachep->freelist_cache, local_flags, nodeid); if (!freelist) return NULL; } else { freelist = addr + colour_off; colour_off += cachep->freelist_size; } page->active = 0; page->s_mem = addr + colour_off; return freelist; } static inline freelist_idx_t get_free_obj(struct page *page, unsigned int idx) { return ((freelist_idx_t *)page->freelist)[idx]; } static inline void set_free_obj(struct page *page, unsigned int idx, freelist_idx_t val) { ((freelist_idx_t *)(page->freelist))[idx] = val; } static void cache_init_objs(struct kmem_cache *cachep, struct page *page) { int i; for (i = 0; i < cachep->num; i++) { void *objp = index_to_obj(cachep, page, i); #if DEBUG /* need to poison the objs? */ if (cachep->flags & SLAB_POISON) poison_obj(cachep, objp, POISON_FREE); 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)) cachep->ctor(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"); } if ((cachep->size % PAGE_SIZE) == 0 && OFF_SLAB(cachep) && cachep->flags & SLAB_POISON) kernel_map_pages(virt_to_page(objp), cachep->size / PAGE_SIZE, 0); #else if (cachep->ctor) cachep->ctor(objp); #endif set_obj_status(page, i, OBJECT_FREE); set_free_obj(page, i, i); } } static void kmem_flagcheck(struct kmem_cache *cachep, gfp_t flags) { if (CONFIG_ZONE_DMA_FLAG) { if (flags & GFP_DMA) BUG_ON(!(cachep->allocflags & GFP_DMA)); else BUG_ON(cachep->allocflags & GFP_DMA); } } static void *slab_get_obj(struct kmem_cache *cachep, struct page *page, int nodeid) { void *objp; objp = index_to_obj(cachep, page, get_free_obj(page, page->active)); page->active++; #if DEBUG WARN_ON(page_to_nid(virt_to_page(objp)) != nodeid); #endif return objp; } static void slab_put_obj(struct kmem_cache *cachep, struct page *page, void *objp, int nodeid) { unsigned int objnr = obj_to_index(cachep, page, objp); #if DEBUG unsigned int i; /* Verify that the slab belongs to the intended node */ WARN_ON(page_to_nid(virt_to_page(objp)) != nodeid); /* Verify double free bug */ for (i = page->active; i < cachep->num; i++) { if (get_free_obj(page, i) == objnr) { printk(KERN_ERR "slab: double free detected in cache " "'%s', objp %p\n", cachep->name, objp); BUG(); } } #endif page->active--; set_free_obj(page, page->active, objnr); } /* * Map pages beginning at addr to the given cache and slab. This is required * for the slab allocator to be able to lookup the cache and slab of a * virtual address for kfree, ksize, and slab debugging. */ static void slab_map_pages(struct kmem_cache *cache, struct page *page, void *freelist) { page->slab_cache = cache; page->freelist = freelist; } /* * 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 int cache_grow(struct kmem_cache *cachep, gfp_t flags, int nodeid, struct page *page) { void *freelist; size_t offset; gfp_t local_flags; struct kmem_cache_node *n; /* * 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)) { pr_emerg("gfp: %u\n", flags & GFP_SLAB_BUG_MASK); BUG(); } local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK); /* Take the node list lock to change the colour_next on this node */ check_irq_off(); n = get_node(cachep, nodeid); spin_lock(&n->list_lock); /* Get colour for the slab, and cal the next value. */ offset = n->colour_next; n->colour_next++; if (n->colour_next >= cachep->colour) n->colour_next = 0; spin_unlock(&n->list_lock); offset *= cachep->colour_off; if (local_flags & __GFP_WAIT) local_irq_enable(); /* * The test for missing atomic flag is performed here, rather than * the more obvious place, simply to reduce the critical path length * in kmem_cache_alloc(). If a caller is seriously mis-behaving they * will eventually be caught here (where it matters). */ kmem_flagcheck(cachep, flags); /* * Get mem for the objs. Attempt to allocate a physical page from * 'nodeid'. */ if (!page) page = kmem_getpages(cachep, local_flags, nodeid); if (!page) goto failed; /* Get slab management. */ freelist = alloc_slabmgmt(cachep, page, offset, local_flags & ~GFP_CONSTRAINT_MASK, nodeid); if (!freelist) goto opps1; slab_map_pages(cachep, page, freelist); cache_init_objs(cachep, page); if (local_flags & __GFP_WAIT) local_irq_disable(); check_irq_off(); spin_lock(&n->list_lock); /* Make slab active. */ list_add_tail(&page->lru, &(n->slabs_free)); STATS_INC_GROWN(cachep); n->free_objects += cachep->num; spin_unlock(&n->list_lock); return 1; opps1: kmem_freepages(cachep, page); failed: if (local_flags & __GFP_WAIT) local_irq_disable(); return 0; } #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)) { printk(KERN_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"); printk(KERN_ERR "%p: 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 page *page; BUG_ON(virt_to_cache(objp) != cachep); objp -= obj_offset(cachep); kfree_debugcheck(objp); page = virt_to_head_page(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, page, objp); BUG_ON(objnr >= cachep->num); BUG_ON(objp != index_to_obj(cachep, page, objnr)); set_obj_status(page, objnr, OBJECT_FREE); if (cachep->flags & SLAB_POISON) { #ifdef CONFIG_DEBUG_PAGEALLOC if ((cachep->size % PAGE_SIZE)==0 && OFF_SLAB(cachep)) { store_stackinfo(cachep, objp, caller); kernel_map_pages(virt_to_page(objp), cachep->size / PAGE_SIZE, 0); } else { poison_obj(cachep, objp, POISON_FREE); } #else poison_obj(cachep, objp, POISON_FREE); #endif } return objp; } #else #define kfree_debugcheck(x) do { } while(0) #define cache_free_debugcheck(x,objp,z) (objp) #endif static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags, bool force_refill) { int batchcount; struct kmem_cache_node *n; struct array_cache *ac; int node; check_irq_off(); node = numa_mem_id(); if (unlikely(force_refill)) goto force_grow; retry: 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); spin_lock(&n->list_lock); /* See if we can refill from the shared array */ if (n->shared && transfer_objects(ac, n->shared, batchcount)) { n->shared->touched = 1; goto alloc_done; } while (batchcount > 0) { struct list_head *entry; struct page *page; /* Get slab alloc is to come from. */ entry = n->slabs_partial.next; if (entry == &n->slabs_partial) { n->free_touched = 1; entry = n->slabs_free.next; if (entry == &n->slabs_free) goto must_grow; } page = list_entry(entry, struct page, lru); check_spinlock_acquired(cachep); /* * The slab was either on partial or free list so * there must be at least one object available for * allocation. */ BUG_ON(page->active >= cachep->num); while (page->active < cachep->num && batchcount--) { STATS_INC_ALLOCED(cachep); STATS_INC_ACTIVE(cachep); STATS_SET_HIGH(cachep); ac_put_obj(cachep, ac, slab_get_obj(cachep, page, node)); } /* move slabp to correct slabp list: */ list_del(&page->lru); if (page->active == cachep->num) list_add(&page->lru, &n->slabs_full); else list_add(&page->lru, &n->slabs_partial); } must_grow: n->free_objects -= ac->avail; alloc_done: spin_unlock(&n->list_lock); if (unlikely(!ac->avail)) { int x; force_grow: x = cache_grow(cachep, flags | GFP_THISNODE, node, NULL); /* cache_grow can reenable interrupts, then ac could change. */ ac = cpu_cache_get(cachep); node = numa_mem_id(); /* no objects in sight? abort */ if (!x && (ac->avail == 0 || force_refill)) return NULL; if (!ac->avail) /* objects refilled by interrupt? */ goto retry; } ac->touched = 1; return ac_get_obj(cachep, ac, flags, force_refill); } static inline void cache_alloc_debugcheck_before(struct kmem_cache *cachep, gfp_t flags) { might_sleep_if(flags & __GFP_WAIT); #if DEBUG kmem_flagcheck(cachep, flags); #endif } #if DEBUG static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep, gfp_t flags, void *objp, unsigned long caller) { struct page *page; if (!objp) return objp; if (cachep->flags & SLAB_POISON) { #ifdef CONFIG_DEBUG_PAGEALLOC if ((cachep->size % PAGE_SIZE) == 0 && OFF_SLAB(cachep)) kernel_map_pages(virt_to_page(objp), cachep->size / PAGE_SIZE, 1); else check_poison_obj(cachep, objp); #else check_poison_obj(cachep, objp); #endif 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"); printk(KERN_ERR "%p: 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; } page = virt_to_head_page(objp); set_obj_status(page, obj_to_index(cachep, page, objp), OBJECT_ACTIVE); objp += obj_offset(cachep); if (cachep->ctor && cachep->flags & SLAB_POISON) cachep->ctor(objp); if (ARCH_SLAB_MINALIGN && ((unsigned long)objp & (ARCH_SLAB_MINALIGN-1))) { printk(KERN_ERR "0x%p: not aligned to ARCH_SLAB_MINALIGN=%d\n", objp, (int)ARCH_SLAB_MINALIGN); } return objp; } #else #define cache_alloc_debugcheck_after(a,b,objp,d) (objp) #endif static bool slab_should_failslab(struct kmem_cache *cachep, gfp_t flags) { if (unlikely(cachep == kmem_cache)) return false; return should_failslab(cachep->object_size, flags, cachep->flags); } static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags) { void *objp; struct array_cache *ac; bool force_refill = false; check_irq_off(); ac = cpu_cache_get(cachep); if (likely(ac->avail)) { ac->touched = 1; objp = ac_get_obj(cachep, ac, flags, false); /* * Allow for the possibility all avail objects are not allowed * by the current flags */ if (objp) { STATS_INC_ALLOCHIT(cachep); goto out; } force_refill = true; } STATS_INC_ALLOCMISS(cachep); objp = cache_alloc_refill(cachep, flags, force_refill); /* * 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 /* * 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; gfp_t local_flags; struct zoneref *z; struct zone *zone; enum zone_type high_zoneidx = gfp_zone(flags); void *obj = NULL; int nid; unsigned int cpuset_mems_cookie; if (flags & __GFP_THISNODE) return NULL; local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK); 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, high_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, flags | GFP_THISNODE, 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. */ struct page *page; if (local_flags & __GFP_WAIT) local_irq_enable(); kmem_flagcheck(cache, flags); page = kmem_getpages(cache, local_flags, numa_mem_id()); if (local_flags & __GFP_WAIT) local_irq_disable(); if (page) { /* * Insert into the appropriate per node queues */ nid = page_to_nid(page); if (cache_grow(cache, flags, nid, page)) { obj = ____cache_alloc_node(cache, flags | GFP_THISNODE, nid); if (!obj) /* * Another processor may allocate the * objects in the slab since we are * not holding any locks. */ goto retry; } else { /* cache_grow already freed obj */ obj = NULL; } } } if (unlikely(!obj && read_mems_allowed_retry(cpuset_mems_cookie))) goto retry_cpuset; return obj; } /* * A interface to enable slab creation on nodeid */ static void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid) { struct list_head *entry; struct page *page; struct kmem_cache_node *n; void *obj; int x; VM_BUG_ON(nodeid < 0 || nodeid >= MAX_NUMNODES); n = get_node(cachep, nodeid); BUG_ON(!n); retry: check_irq_off(); spin_lock(&n->list_lock); entry = n->slabs_partial.next; if (entry == &n->slabs_partial) { n->free_touched = 1; entry = n->slabs_free.next; if (entry == &n->slabs_free) goto must_grow; } page = list_entry(entry, struct page, lru); check_spinlock_acquired_node(cachep, nodeid); STATS_INC_NODEALLOCS(cachep); STATS_INC_ACTIVE(cachep); STATS_SET_HIGH(cachep); BUG_ON(page->active == cachep->num); obj = slab_get_obj(cachep, page, nodeid); n->free_objects--; /* move slabp to correct slabp list: */ list_del(&page->lru); if (page->active == cachep->num) list_add(&page->lru, &n->slabs_full); else list_add(&page->lru, &n->slabs_partial); spin_unlock(&n->list_lock); goto done; must_grow: spin_unlock(&n->list_lock); x = cache_grow(cachep, flags | GFP_THISNODE, nodeid, NULL); if (x) goto retry; return fallback_alloc(cachep, flags); done: return obj; } static __always_inline void * slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid, unsigned long caller) { unsigned long save_flags; void *ptr; int slab_node = numa_mem_id(); flags &= gfp_allowed_mask; lockdep_trace_alloc(flags); if (slab_should_failslab(cachep, flags)) return NULL; cachep = memcg_kmem_get_cache(cachep, flags); cache_alloc_debugcheck_before(cachep, flags); local_irq_save(save_flags); if (nodeid == NUMA_NO_NODE) nodeid = slab_node; if (unlikely(!get_node(cachep, nodeid))) { /* Node not bootstrapped yet */ ptr = fallback_alloc(cachep, flags); goto out; } if (nodeid == slab_node) { /* * 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. */ ptr = ____cache_alloc(cachep, flags); if (ptr) goto out; } /* ___cache_alloc_node can fall back to other nodes */ ptr = ____cache_alloc_node(cachep, flags, nodeid); out: local_irq_restore(save_flags); ptr = cache_alloc_debugcheck_after(cachep, flags, ptr, caller); kmemleak_alloc_recursive(ptr, cachep->object_size, 1, cachep->flags, flags); if (likely(ptr)) { kmemcheck_slab_alloc(cachep, flags, ptr, cachep->object_size); if (unlikely(flags & __GFP_ZERO)) memset(ptr, 0, cachep->object_size); } memcg_kmem_put_cache(cachep); return ptr; } static __always_inline void * __do_cache_alloc(struct kmem_cache *cache, gfp_t flags) { void *objp; if (current->mempolicy || cpuset_do_slab_mem_spread()) { objp = alternate_node_alloc(cache, flags); if (objp) goto out; } objp = ____cache_alloc(cache, flags); /* * 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(cache, flags, numa_mem_id()); out: return objp; } #else static __always_inline void * __do_cache_alloc(struct kmem_cache *cachep, gfp_t flags) { return ____cache_alloc(cachep, flags); } #endif /* CONFIG_NUMA */ static __always_inline void * slab_alloc(struct kmem_cache *cachep, gfp_t flags, unsigned long caller) { unsigned long save_flags; void *objp; flags &= gfp_allowed_mask; lockdep_trace_alloc(flags); if (slab_should_failslab(cachep, flags)) return NULL; cachep = memcg_kmem_get_cache(cachep, flags); cache_alloc_debugcheck_before(cachep, flags); local_irq_save(save_flags); objp = __do_cache_alloc(cachep, flags); local_irq_restore(save_flags); objp = cache_alloc_debugcheck_after(cachep, flags, objp, caller); kmemleak_alloc_recursive(objp, cachep->object_size, 1, cachep->flags, flags); prefetchw(objp); if (likely(objp)) { kmemcheck_slab_alloc(cachep, flags, objp, cachep->object_size); if (unlikely(flags & __GFP_ZERO)) memset(objp, 0, cachep->object_size); } memcg_kmem_put_cache(cachep); 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); for (i = 0; i < nr_objects; i++) { void *objp; struct page *page; clear_obj_pfmemalloc(&objpp[i]); objp = objpp[i]; page = virt_to_head_page(objp); list_del(&page->lru); check_spinlock_acquired_node(cachep, node); slab_put_obj(cachep, page, objp, node); STATS_DEC_ACTIVE(cachep); n->free_objects++; /* fixup slab chains */ if (page->active == 0) { if (n->free_objects > n->free_limit) { n->free_objects -= cachep->num; list_add_tail(&page->lru, list); } else { list_add(&page->lru, &n->slabs_free); } } 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(&page->lru, &n->slabs_partial); } } } 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; #if DEBUG BUG_ON(!batchcount || batchcount > ac->avail); #endif 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 list_head *p; p = n->slabs_free.next; while (p != &(n->slabs_free)) { struct page *page; page = list_entry(p, struct page, lru); BUG_ON(page->active); i++; p = p->next; } STATS_SET_FREEABLE(cachep, i); } #endif spin_unlock(&n->list_lock); slabs_destroy(cachep, &list); ac->avail -= batchcount; memmove(ac->entry, &(ac->entry[batchcount]), sizeof(void *)*ac->avail); } /* * 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 inline 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); kmemcheck_slab_free(cachep, objp, cachep->object_size); /* * 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); } ac_put_obj(cachep, ac, objp); } /** * 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. */ void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags) { void *ret = slab_alloc(cachep, flags, _RET_IP_); trace_kmem_cache_alloc(_RET_IP_, ret, cachep->object_size, cachep->size, flags); return ret; } EXPORT_SYMBOL(kmem_cache_alloc); #ifdef CONFIG_TRACING void * kmem_cache_alloc_trace(struct kmem_cache *cachep, gfp_t flags, size_t size) { void *ret; ret = slab_alloc(cachep, flags, _RET_IP_); trace_kmalloc(_RET_IP_, ret, 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. */ void *kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid) { void *ret = slab_alloc_node(cachep, flags, nodeid, _RET_IP_); trace_kmem_cache_alloc_node(_RET_IP_, ret, 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, _RET_IP_); trace_kmalloc_node(_RET_IP_, ret, 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; cachep = kmalloc_slab(size, flags); if (unlikely(ZERO_OR_NULL_PTR(cachep))) return cachep; return kmem_cache_alloc_node_trace(cachep, flags, node, size); } 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 */ /** * __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 */ static __always_inline void *__do_kmalloc(size_t size, gfp_t flags, unsigned long caller) { struct kmem_cache *cachep; void *ret; cachep = kmalloc_slab(size, flags); if (unlikely(ZERO_OR_NULL_PTR(cachep))) return cachep; ret = slab_alloc(cachep, flags, caller); trace_kmalloc(caller, ret, 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; 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); trace_kmem_cache_free(_RET_IP_, objp); } EXPORT_SYMBOL(kmem_cache_free); /** * 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); 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 alloc_kmem_cache_node(struct kmem_cache *cachep, gfp_t gfp) { int node; struct kmem_cache_node *n; struct array_cache *new_shared; struct alien_cache **new_alien = NULL; for_each_online_node(node) { if (use_alien_caches) { new_alien = alloc_alien_cache(node, cachep->limit, gfp); if (!new_alien) goto fail; } new_shared = NULL; if (cachep->shared) { new_shared = alloc_arraycache(node, cachep->shared*cachep->batchcount, 0xbaadf00d, gfp); if (!new_shared) { free_alien_cache(new_alien); goto fail; } } n = get_node(cachep, node); if (n) { struct array_cache *shared = n->shared; LIST_HEAD(list); spin_lock_irq(&n->list_lock); if (shared) free_block(cachep, shared->entry, shared->avail, node, &list); n->shared = new_shared; if (!n->alien) { n->alien = new_alien; new_alien = NULL; } n->free_limit = (1 + nr_cpus_node(node)) * cachep->batchcount + cachep->num; spin_unlock_irq(&n->list_lock); slabs_destroy(cachep, &list); kfree(shared); free_alien_cache(new_alien); continue; } n = kmalloc_node(sizeof(struct kmem_cache_node), gfp, node); if (!n) { free_alien_cache(new_alien); kfree(new_shared); goto fail; } kmem_cache_node_init(n); n->next_reap = jiffies + REAPTIMEOUT_NODE + ((unsigned long)cachep) % REAPTIMEOUT_NODE; n->shared = new_shared; n->alien = new_alien; n->free_limit = (1 + nr_cpus_node(node)) * cachep->batchcount + cachep->num; cachep->node[node] = n; } 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; kick_all_cpus_sync(); check_irq_on(); cachep->batchcount = batchcount; cachep->limit = limit; cachep->shared = shared; if (!prev) goto alloc_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); alloc_node: return alloc_kmem_cache_node(cachep, gfp); } static int do_tune_cpucache(struct kmem_cache *cachep, int limit, int batchcount, int shared, gfp_t gfp) { int ret; struct kmem_cache *c = NULL; int i = 0; ret = __do_tune_cpucache(cachep, limit, batchcount, shared, gfp); if (slab_state < FULL) return ret; if ((ret < 0) || !is_root_cache(cachep)) return ret; VM_BUG_ON(!mutex_is_locked(&slab_mutex)); for_each_memcg_cache_index(i) { c = cache_from_memcg_idx(cachep, i); if (c) /* return value determined by the parent cache only */ __do_tune_cpucache(c, limit, batchcount, shared, gfp); } return ret; } /* 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; if (!is_root_cache(cachep)) { struct kmem_cache *root = memcg_root_cache(cachep); limit = root->limit; shared = root->shared; batchcount = root->batchcount; } if (limit && shared && batchcount) goto skip_setup; /* * 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; skip_setup: err = do_tune_cpucache(cachep, limit, batchcount, shared, gfp); if (err) printk(KERN_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 force, int node) { LIST_HEAD(list); int tofree; if (!ac || !ac->avail) return; if (ac->touched && !force) { ac->touched = 0; } else { spin_lock_irq(&n->list_lock); if (ac->avail) { tofree = force ? 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); } 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), 0, 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, 0, 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(work, round_jiffies_relative(REAPTIMEOUT_AC)); } #ifdef CONFIG_SLABINFO void get_slabinfo(struct kmem_cache *cachep, struct slabinfo *sinfo) { struct page *page; unsigned long active_objs; unsigned long num_objs; unsigned long active_slabs = 0; unsigned long num_slabs, free_objects = 0, shared_avail = 0; const char *name; char *error = NULL; int node; struct kmem_cache_node *n; active_objs = 0; num_slabs = 0; for_each_kmem_cache_node(cachep, node, n) { check_irq_on(); spin_lock_irq(&n->list_lock); list_for_each_entry(page, &n->slabs_full, lru) { if (page->active != cachep->num && !error) error = "slabs_full accounting error"; active_objs += cachep->num; active_slabs++; } list_for_each_entry(page, &n->slabs_partial, lru) { if (page->active == cachep->num && !error) error = "slabs_partial accounting error"; if (!page->active && !error) error = "slabs_partial accounting error"; active_objs += page->active; active_slabs++; } list_for_each_entry(page, &n->slabs_free, lru) { if (page->active && !error) error = "slabs_free accounting error"; num_slabs++; } free_objects += n->free_objects; if (n->shared) shared_avail += n->shared->avail; spin_unlock_irq(&n->list_lock); } num_slabs += active_slabs; num_objs = num_slabs * cachep->num; if (num_objs - active_objs != free_objects && !error) error = "free_objects accounting error"; name = cachep->name; if (error) printk(KERN_ERR "slab: cache %s error: %s\n", name, error); sinfo->active_objs = active_objs; sinfo->num_objs = num_objs; sinfo->active_slabs = active_slabs; sinfo->num_slabs = num_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 */ 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_DEBUG_SLAB_LEAK static inline int add_caller(unsigned long *n, unsigned long v) { unsigned long *p; int l; if (!v) return 1; l = n[1]; p = n + 2; while (l) { int i = l/2; unsigned long *q = p + 2 * i; if (*q == v) { q[1]++; return 1; } if (*q > v) { l = i; } else { p = q + 2; l -= i + 1; } } if (++n[1] == n[0]) return 0; memmove(p + 2, p, n[1] * 2 * sizeof(unsigned long) - ((void *)p - (void *)n)); p[0] = v; p[1] = 1; return 1; } static void handle_slab(unsigned long *n, struct kmem_cache *c, struct page *page) { void *p; int i; if (n[0] == n[1]) return; for (i = 0, p = page->s_mem; i < c->num; i++, p += c->size) { if (get_obj_status(page, i) != OBJECT_ACTIVE) continue; if (!add_caller(n, (unsigned long)*dbg_userword(c, p))) return; } } static void show_symbol(struct seq_file *m, unsigned long address) { #ifdef CONFIG_KALLSYMS unsigned long offset, size; char modname[MODULE_NAME_LEN], name[KSYM_NAME_LEN]; if (lookup_symbol_attrs(address, &size, &offset, modname, name) == 0) { seq_printf(m, "%s+%#lx/%#lx", name, offset, size); if (modname[0]) seq_printf(m, " [%s]", modname); return; } #endif seq_printf(m, "%p", (void *)address); } static int leaks_show(struct seq_file *m, void *p) { struct kmem_cache *cachep = list_entry(p, struct kmem_cache, list); struct page *page; struct kmem_cache_node *n; const char *name; unsigned long *x = m->private; int node; int i; if (!(cachep->flags & SLAB_STORE_USER)) return 0; if (!(cachep->flags & SLAB_RED_ZONE)) return 0; /* OK, we can do it */ x[1] = 0; for_each_kmem_cache_node(cachep, node, n) { check_irq_on(); spin_lock_irq(&n->list_lock); list_for_each_entry(page, &n->slabs_full, lru) handle_slab(x, cachep, page); list_for_each_entry(page, &n->slabs_partial, lru) handle_slab(x, cachep, page); spin_unlock_irq(&n->list_lock); } name = cachep->name; if (x[0] == x[1]) { /* Increase the buffer size */ mutex_unlock(&slab_mutex); m->private = kzalloc(x[0] * 4 * sizeof(unsigned long), GFP_KERNEL); if (!m->private) { /* Too bad, we are really out */ m->private = x; mutex_lock(&slab_mutex); return -ENOMEM; } *(unsigned long *)m->private = x[0] * 2; kfree(x); mutex_lock(&slab_mutex); /* Now make sure this entry will be retried */ m->count = m->size; return 0; } for (i = 0; i < x[1]; i++) { seq_printf(m, "%s: %lu ", name, x[2*i+3]); show_symbol(m, x[2*i+2]); seq_putc(m, '\n'); } return 0; } static const struct seq_operations slabstats_op = { .start = slab_start, .next = slab_next, .stop = slab_stop, .show = leaks_show, }; static int slabstats_open(struct inode *inode, struct file *file) { unsigned long *n; n = __seq_open_private(file, &slabstats_op, PAGE_SIZE); if (!n) return -ENOMEM; *n = PAGE_SIZE / (2 * sizeof(unsigned long)); return 0; } static const struct file_operations proc_slabstats_operations = { .open = slabstats_open, .read = seq_read, .llseek = seq_lseek, .release = seq_release_private, }; #endif static int __init slab_proc_init(void) { #ifdef CONFIG_DEBUG_SLAB_LEAK proc_create("slab_allocators", 0, NULL, &proc_slabstats_operations); #endif return 0; } module_init(slab_proc_init); #endif /** * ksize - get the actual amount of memory allocated for a given object * @objp: Pointer to the object * * kmalloc may internally round up allocations and return more memory * than requested. ksize() can be used to determine the actual amount of * memory allocated. The caller may use this additional memory, even though * a smaller amount of memory was initially specified with the kmalloc call. * The caller must guarantee that objp points to a valid object previously * allocated with either kmalloc() or kmem_cache_alloc(). The object * must not be freed during the duration of the call. */ size_t ksize(const void *objp) { BUG_ON(!objp); if (unlikely(objp == ZERO_SIZE_PTR)) return 0; return virt_to_cache(objp)->object_size; } EXPORT_SYMBOL(ksize);