/* * 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 intializations 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 kmem_cache_t 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 semaphore 'cache_chain_sem'. * 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. * */ #include <linux/config.h> #include <linux/slab.h> #include <linux/mm.h> #include <linux/swap.h> #include <linux/cache.h> #include <linux/interrupt.h> #include <linux/init.h> #include <linux/compiler.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 <asm/uaccess.h> #include <asm/cacheflush.h> #include <asm/tlbflush.h> #include <asm/page.h> /* * DEBUG - 1 for kmem_cache_create() to honour; SLAB_DEBUG_INITIAL, * 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 *) #ifndef cache_line_size #define cache_line_size() L1_CACHE_BYTES #endif #ifndef ARCH_KMALLOC_MINALIGN /* * Enforce a minimum alignment for the kmalloc caches. * Usually, the kmalloc caches are cache_line_size() aligned, except when * DEBUG and FORCED_DEBUG are enabled, then they are BYTES_PER_WORD aligned. * Some archs want to perform DMA into kmalloc caches and need a guaranteed * alignment larger than BYTES_PER_WORD. ARCH_KMALLOC_MINALIGN allows that. * Note that this flag disables some debug features. */ #define ARCH_KMALLOC_MINALIGN 0 #endif #ifndef ARCH_SLAB_MINALIGN /* * Enforce a minimum alignment for all caches. * Intended for archs that get misalignment faults even for BYTES_PER_WORD * aligned buffers. Includes ARCH_KMALLOC_MINALIGN. * If possible: Do not enable this flag for CONFIG_DEBUG_SLAB, it disables * some debug features. */ #define ARCH_SLAB_MINALIGN 0 #endif #ifndef ARCH_KMALLOC_FLAGS #define ARCH_KMALLOC_FLAGS SLAB_HWCACHE_ALIGN #endif /* Legal flag mask for kmem_cache_create(). */ #if DEBUG # define CREATE_MASK (SLAB_DEBUG_INITIAL | SLAB_RED_ZONE | \ SLAB_POISON | SLAB_HWCACHE_ALIGN | \ SLAB_NO_REAP | SLAB_CACHE_DMA | \ SLAB_MUST_HWCACHE_ALIGN | SLAB_STORE_USER | \ SLAB_RECLAIM_ACCOUNT | SLAB_PANIC | \ SLAB_DESTROY_BY_RCU) #else # define CREATE_MASK (SLAB_HWCACHE_ALIGN | SLAB_NO_REAP | \ SLAB_CACHE_DMA | SLAB_MUST_HWCACHE_ALIGN | \ SLAB_RECLAIM_ACCOUNT | SLAB_PANIC | \ SLAB_DESTROY_BY_RCU) #endif /* * kmem_bufctl_t: * * Bufctl's are used for linking objs within a slab * linked offsets. * * This implementation relies on "struct page" for locating the cache & * slab an object belongs to. * This allows the bufctl structure to be small (one int), but limits * the number of objects a slab (not a cache) can contain when off-slab * bufctls are used. The limit is the size of the largest general cache * that does not use off-slab slabs. * For 32bit archs with 4 kB pages, is this 56. * This is not serious, as it is only for large objects, when it is unwise * to have too many per slab. * Note: This limit can be raised by introducing a general cache whose size * is less than 512 (PAGE_SIZE<<3), but greater than 256. */ #define BUFCTL_END (((kmem_bufctl_t)(~0U))-0) #define BUFCTL_FREE (((kmem_bufctl_t)(~0U))-1) #define SLAB_LIMIT (((kmem_bufctl_t)(~0U))-2) /* Max number of objs-per-slab for caches which use off-slab slabs. * Needed to avoid a possible looping condition in cache_grow(). */ static unsigned long offslab_limit; /* * struct slab * * Manages the objs in a slab. Placed either at the beginning of mem allocated * for a slab, or allocated from an general cache. * Slabs are chained into three list: fully used, partial, fully free slabs. */ struct slab { struct list_head list; unsigned long colouroff; void *s_mem; /* including colour offset */ unsigned int inuse; /* num of objs active in slab */ kmem_bufctl_t free; }; /* * struct slab_rcu * * slab_destroy on a SLAB_DESTROY_BY_RCU cache uses this structure to * arrange for kmem_freepages to be called via RCU. This is useful if * we need to approach a kernel structure obliquely, from its address * obtained without the usual locking. We can lock the structure to * stabilize it and check it's still at the given address, only if we * can be sure that the memory has not been meanwhile reused for some * other kind of object (which our subsystem's lock might corrupt). * * rcu_read_lock before reading the address, then rcu_read_unlock after * taking the spinlock within the structure expected at that address. * * We assume struct slab_rcu can overlay struct slab when destroying. */ struct slab_rcu { struct rcu_head head; kmem_cache_t *cachep; void *addr; }; /* * struct array_cache * * Per cpu structures * 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; }; /* 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]; }; /* * The slab lists of all objects. * Hopefully reduce the internal fragmentation * NUMA: The spinlock could be moved from the kmem_cache_t * into this structure, too. Figure out what causes * fewer cross-node spinlock operations. */ struct kmem_list3 { struct list_head slabs_partial; /* partial list first, better asm code */ struct list_head slabs_full; struct list_head slabs_free; unsigned long free_objects; int free_touched; unsigned long next_reap; struct array_cache *shared; }; #define LIST3_INIT(parent) \ { \ .slabs_full = LIST_HEAD_INIT(parent.slabs_full), \ .slabs_partial = LIST_HEAD_INIT(parent.slabs_partial), \ .slabs_free = LIST_HEAD_INIT(parent.slabs_free) \ } #define list3_data(cachep) \ (&(cachep)->lists) /* NUMA: per-node */ #define list3_data_ptr(cachep, ptr) \ list3_data(cachep) /* * kmem_cache_t * * manages a cache. */ struct kmem_cache_s { /* 1) per-cpu data, touched during every alloc/free */ struct array_cache *array[NR_CPUS]; unsigned int batchcount; unsigned int limit; /* 2) touched by every alloc & free from the backend */ struct kmem_list3 lists; /* NUMA: kmem_3list_t *nodelists[MAX_NUMNODES] */ unsigned int objsize; unsigned int flags; /* constant flags */ unsigned int num; /* # of objs per slab */ unsigned int free_limit; /* upper limit of objects in the lists */ spinlock_t spinlock; /* 3) cache_grow/shrink */ /* order of pgs per slab (2^n) */ unsigned int gfporder; /* force GFP flags, e.g. GFP_DMA */ unsigned int gfpflags; size_t colour; /* cache colouring range */ unsigned int colour_off; /* colour offset */ unsigned int colour_next; /* cache colouring */ kmem_cache_t *slabp_cache; unsigned int slab_size; unsigned int dflags; /* dynamic flags */ /* constructor func */ void (*ctor)(void *, kmem_cache_t *, unsigned long); /* de-constructor func */ void (*dtor)(void *, kmem_cache_t *, unsigned long); /* 4) cache creation/removal */ const char *name; struct list_head next; /* 5) statistics */ #if STATS unsigned long num_active; unsigned long num_allocations; unsigned long high_mark; unsigned long grown; unsigned long reaped; unsigned long errors; unsigned long max_freeable; unsigned long node_allocs; atomic_t allochit; atomic_t allocmiss; atomic_t freehit; atomic_t freemiss; #endif #if DEBUG int dbghead; int reallen; #endif }; #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. * * OTHO the cpuarrays can contain lots of objects, * which could lock up otherwise freeable slabs. */ #define REAPTIMEOUT_CPUC (2*HZ) #define REAPTIMEOUT_LIST3 (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_INC_REAPED(x) ((x)->reaped++) #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_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_INC_REAPED(x) do { } 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_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 /* Magic nums for obj red zoning. * Placed in the first word before and the first word after an obj. */ #define RED_INACTIVE 0x5A2CF071UL /* when obj is inactive */ #define RED_ACTIVE 0x170FC2A5UL /* when obj is active */ /* ...and for poisoning */ #define POISON_INUSE 0x5a /* for use-uninitialised poisoning */ #define POISON_FREE 0x6b /* for use-after-free poisoning */ #define POISON_END 0xa5 /* end-byte of poisoning */ /* memory layout of objects: * 0 : objp * 0 .. cachep->dbghead - 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->dbghead - BYTES_PER_WORD .. cachep->dbghead - 1: * redzone word. * cachep->dbghead: The real object. * cachep->objsize - 2* BYTES_PER_WORD: redzone word [BYTES_PER_WORD long] * cachep->objsize - 1* BYTES_PER_WORD: last caller address [BYTES_PER_WORD long] */ static int obj_dbghead(kmem_cache_t *cachep) { return cachep->dbghead; } static int obj_reallen(kmem_cache_t *cachep) { return cachep->reallen; } static unsigned long *dbg_redzone1(kmem_cache_t *cachep, void *objp) { BUG_ON(!(cachep->flags & SLAB_RED_ZONE)); return (unsigned long*) (objp+obj_dbghead(cachep)-BYTES_PER_WORD); } static unsigned long *dbg_redzone2(kmem_cache_t *cachep, void *objp) { BUG_ON(!(cachep->flags & SLAB_RED_ZONE)); if (cachep->flags & SLAB_STORE_USER) return (unsigned long*) (objp+cachep->objsize-2*BYTES_PER_WORD); return (unsigned long*) (objp+cachep->objsize-BYTES_PER_WORD); } static void **dbg_userword(kmem_cache_t *cachep, void *objp) { BUG_ON(!(cachep->flags & SLAB_STORE_USER)); return (void**)(objp+cachep->objsize-BYTES_PER_WORD); } #else #define obj_dbghead(x) 0 #define obj_reallen(cachep) (cachep->objsize) #define dbg_redzone1(cachep, objp) ({BUG(); (unsigned long *)NULL;}) #define dbg_redzone2(cachep, objp) ({BUG(); (unsigned long *)NULL;}) #define dbg_userword(cachep, objp) ({BUG(); (void **)NULL;}) #endif /* * Maximum size of an obj (in 2^order pages) * and absolute limit for the gfp order. */ #if defined(CONFIG_LARGE_ALLOCS) #define MAX_OBJ_ORDER 13 /* up to 32Mb */ #define MAX_GFP_ORDER 13 /* up to 32Mb */ #elif defined(CONFIG_MMU) #define MAX_OBJ_ORDER 5 /* 32 pages */ #define MAX_GFP_ORDER 5 /* 32 pages */ #else #define MAX_OBJ_ORDER 8 /* up to 1Mb */ #define MAX_GFP_ORDER 8 /* up to 1Mb */ #endif /* * Do not go above this order unless 0 objects fit into the slab. */ #define BREAK_GFP_ORDER_HI 1 #define BREAK_GFP_ORDER_LO 0 static int slab_break_gfp_order = BREAK_GFP_ORDER_LO; /* Macros for storing/retrieving the cachep and or slab from the * global 'mem_map'. These are used to find the slab an obj belongs to. * With kfree(), these are used to find the cache which an obj belongs to. */ #define SET_PAGE_CACHE(pg,x) ((pg)->lru.next = (struct list_head *)(x)) #define GET_PAGE_CACHE(pg) ((kmem_cache_t *)(pg)->lru.next) #define SET_PAGE_SLAB(pg,x) ((pg)->lru.prev = (struct list_head *)(x)) #define GET_PAGE_SLAB(pg) ((struct slab *)(pg)->lru.prev) /* These are the default caches for kmalloc. Custom caches can have other sizes. */ struct cache_sizes malloc_sizes[] = { #define CACHE(x) { .cs_size = (x) }, #include <linux/kmalloc_sizes.h> CACHE(ULONG_MAX) #undef CACHE }; EXPORT_SYMBOL(malloc_sizes); /* Must match cache_sizes above. Out of line to keep cache footprint low. */ struct cache_names { char *name; char *name_dma; }; static struct cache_names __initdata cache_names[] = { #define CACHE(x) { .name = "size-" #x, .name_dma = "size-" #x "(DMA)" }, #include <linux/kmalloc_sizes.h> { NULL, } #undef CACHE }; static struct arraycache_init initarray_cache __initdata = { { 0, BOOT_CPUCACHE_ENTRIES, 1, 0} }; static struct arraycache_init initarray_generic = { { 0, BOOT_CPUCACHE_ENTRIES, 1, 0} }; /* internal cache of cache description objs */ static kmem_cache_t cache_cache = { .lists = LIST3_INIT(cache_cache.lists), .batchcount = 1, .limit = BOOT_CPUCACHE_ENTRIES, .objsize = sizeof(kmem_cache_t), .flags = SLAB_NO_REAP, .spinlock = SPIN_LOCK_UNLOCKED, .name = "kmem_cache", #if DEBUG .reallen = sizeof(kmem_cache_t), #endif }; /* Guard access to the cache-chain. */ static struct semaphore cache_chain_sem; static struct list_head cache_chain; /* * vm_enough_memory() looks at this to determine how many * slab-allocated pages are possibly freeable under pressure * * SLAB_RECLAIM_ACCOUNT turns this on per-slab */ atomic_t slab_reclaim_pages; EXPORT_SYMBOL(slab_reclaim_pages); /* * chicken and egg problem: delay the per-cpu array allocation * until the general caches are up. */ static enum { NONE, PARTIAL, FULL } g_cpucache_up; static DEFINE_PER_CPU(struct work_struct, reap_work); static void free_block(kmem_cache_t* cachep, void** objpp, int len); static void enable_cpucache (kmem_cache_t *cachep); static void cache_reap (void *unused); static inline void **ac_entry(struct array_cache *ac) { return (void**)(ac+1); } static inline struct array_cache *ac_data(kmem_cache_t *cachep) { return cachep->array[smp_processor_id()]; } static inline kmem_cache_t *__find_general_cachep(size_t size, unsigned int __nocast gfpflags) { struct cache_sizes *csizep = malloc_sizes; #if DEBUG /* This happens if someone tries to call * kmem_cache_create(), or __kmalloc(), before * the generic caches are initialized. */ BUG_ON(csizep->cs_cachep == NULL); #endif while (size > csizep->cs_size) csizep++; /* * Really subtile: The last entry with cs->cs_size==ULONG_MAX * has cs_{dma,}cachep==NULL. Thus no special case * for large kmalloc calls required. */ if (unlikely(gfpflags & GFP_DMA)) return csizep->cs_dmacachep; return csizep->cs_cachep; } kmem_cache_t *kmem_find_general_cachep(size_t size, unsigned int __nocast gfpflags) { return __find_general_cachep(size, gfpflags); } EXPORT_SYMBOL(kmem_find_general_cachep); /* Cal the num objs, wastage, and bytes left over for a given slab size. */ static void cache_estimate(unsigned long gfporder, size_t size, size_t align, int flags, size_t *left_over, unsigned int *num) { int i; size_t wastage = PAGE_SIZE<<gfporder; size_t extra = 0; size_t base = 0; if (!(flags & CFLGS_OFF_SLAB)) { base = sizeof(struct slab); extra = sizeof(kmem_bufctl_t); } i = 0; while (i*size + ALIGN(base+i*extra, align) <= wastage) i++; if (i > 0) i--; if (i > SLAB_LIMIT) i = SLAB_LIMIT; *num = i; wastage -= i*size; wastage -= ALIGN(base+i*extra, align); *left_over = wastage; } #define slab_error(cachep, msg) __slab_error(__FUNCTION__, cachep, msg) static void __slab_error(const char *function, kmem_cache_t *cachep, char *msg) { printk(KERN_ERR "slab error in %s(): cache `%s': %s\n", function, cachep->name, msg); dump_stack(); } /* * 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 __devinit start_cpu_timer(int cpu) { struct work_struct *reap_work = &per_cpu(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->func == NULL) { INIT_WORK(reap_work, cache_reap, NULL); schedule_delayed_work_on(cpu, reap_work, HZ + 3 * cpu); } } static struct array_cache *alloc_arraycache(int cpu, int entries, int batchcount) { int memsize = sizeof(void*)*entries+sizeof(struct array_cache); struct array_cache *nc = NULL; if (cpu == -1) nc = kmalloc(memsize, GFP_KERNEL); else nc = kmalloc_node(memsize, GFP_KERNEL, cpu_to_node(cpu)); if (nc) { nc->avail = 0; nc->limit = entries; nc->batchcount = batchcount; nc->touched = 0; } return nc; } static int __devinit cpuup_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) { long cpu = (long)hcpu; kmem_cache_t* cachep; switch (action) { case CPU_UP_PREPARE: down(&cache_chain_sem); list_for_each_entry(cachep, &cache_chain, next) { struct array_cache *nc; nc = alloc_arraycache(cpu, cachep->limit, cachep->batchcount); if (!nc) goto bad; spin_lock_irq(&cachep->spinlock); cachep->array[cpu] = nc; cachep->free_limit = (1+num_online_cpus())*cachep->batchcount + cachep->num; spin_unlock_irq(&cachep->spinlock); } up(&cache_chain_sem); break; case CPU_ONLINE: start_cpu_timer(cpu); break; #ifdef CONFIG_HOTPLUG_CPU case CPU_DEAD: /* fall thru */ case CPU_UP_CANCELED: down(&cache_chain_sem); list_for_each_entry(cachep, &cache_chain, next) { struct array_cache *nc; spin_lock_irq(&cachep->spinlock); /* cpu is dead; no one can alloc from it. */ nc = cachep->array[cpu]; cachep->array[cpu] = NULL; cachep->free_limit -= cachep->batchcount; free_block(cachep, ac_entry(nc), nc->avail); spin_unlock_irq(&cachep->spinlock); kfree(nc); } up(&cache_chain_sem); break; #endif } return NOTIFY_OK; bad: up(&cache_chain_sem); return NOTIFY_BAD; } static struct notifier_block cpucache_notifier = { &cpuup_callback, NULL, 0 }; /* Initialisation. * Called after the gfp() functions have been enabled, and before smp_init(). */ void __init kmem_cache_init(void) { size_t left_over; struct cache_sizes *sizes; struct cache_names *names; /* * Fragmentation resistance on low memory - only use bigger * page orders on machines with more than 32MB of memory. */ if (num_physpages > (32 << 20) >> PAGE_SHIFT) slab_break_gfp_order = BREAK_GFP_ORDER_HI; /* Bootstrap is tricky, because several objects are allocated * from caches that do not exist yet: * 1) initialize the cache_cache cache: it contains the kmem_cache_t * structures of all caches, except cache_cache itself: cache_cache * is statically allocated. * Initially an __init data area is used for the head array, it's * replaced with a kmalloc allocated array at the end of the bootstrap. * 2) Create the first kmalloc cache. * The kmem_cache_t 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 cache_cache and the first * kmalloc cache with kmalloc allocated arrays. * 5) Resize the head arrays of the kmalloc caches to their final sizes. */ /* 1) create the cache_cache */ init_MUTEX(&cache_chain_sem); INIT_LIST_HEAD(&cache_chain); list_add(&cache_cache.next, &cache_chain); cache_cache.colour_off = cache_line_size(); cache_cache.array[smp_processor_id()] = &initarray_cache.cache; cache_cache.objsize = ALIGN(cache_cache.objsize, cache_line_size()); cache_estimate(0, cache_cache.objsize, cache_line_size(), 0, &left_over, &cache_cache.num); if (!cache_cache.num) BUG(); cache_cache.colour = left_over/cache_cache.colour_off; cache_cache.colour_next = 0; cache_cache.slab_size = ALIGN(cache_cache.num*sizeof(kmem_bufctl_t) + sizeof(struct slab), cache_line_size()); /* 2+3) create the kmalloc caches */ sizes = malloc_sizes; names = cache_names; while (sizes->cs_size != ULONG_MAX) { /* For performance, all the general caches are L1 aligned. * This should be particularly beneficial on SMP boxes, as it * eliminates "false sharing". * Note for systems short on memory removing the alignment will * allow tighter packing of the smaller caches. */ sizes->cs_cachep = kmem_cache_create(names->name, sizes->cs_size, ARCH_KMALLOC_MINALIGN, (ARCH_KMALLOC_FLAGS | SLAB_PANIC), NULL, NULL); /* Inc off-slab bufctl limit until the ceiling is hit. */ if (!(OFF_SLAB(sizes->cs_cachep))) { offslab_limit = sizes->cs_size-sizeof(struct slab); offslab_limit /= sizeof(kmem_bufctl_t); } sizes->cs_dmacachep = kmem_cache_create(names->name_dma, sizes->cs_size, ARCH_KMALLOC_MINALIGN, (ARCH_KMALLOC_FLAGS | SLAB_CACHE_DMA | SLAB_PANIC), NULL, NULL); sizes++; names++; } /* 4) Replace the bootstrap head arrays */ { void * ptr; ptr = kmalloc(sizeof(struct arraycache_init), GFP_KERNEL); local_irq_disable(); BUG_ON(ac_data(&cache_cache) != &initarray_cache.cache); memcpy(ptr, ac_data(&cache_cache), sizeof(struct arraycache_init)); cache_cache.array[smp_processor_id()] = ptr; local_irq_enable(); ptr = kmalloc(sizeof(struct arraycache_init), GFP_KERNEL); local_irq_disable(); BUG_ON(ac_data(malloc_sizes[0].cs_cachep) != &initarray_generic.cache); memcpy(ptr, ac_data(malloc_sizes[0].cs_cachep), sizeof(struct arraycache_init)); malloc_sizes[0].cs_cachep->array[smp_processor_id()] = ptr; local_irq_enable(); } /* 5) resize the head arrays to their final sizes */ { kmem_cache_t *cachep; down(&cache_chain_sem); list_for_each_entry(cachep, &cache_chain, next) enable_cpucache(cachep); up(&cache_chain_sem); } /* Done! */ g_cpucache_up = FULL; /* Register a cpu startup notifier callback * that initializes ac_data for all new cpus */ register_cpu_notifier(&cpucache_notifier); /* 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 gfp. */ for (cpu = 0; cpu < NR_CPUS; cpu++) { if (cpu_online(cpu)) start_cpu_timer(cpu); } return 0; } __initcall(cpucache_init); /* * Interface to system's page allocator. No need to hold the cache-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 void *kmem_getpages(kmem_cache_t *cachep, unsigned int __nocast flags, int nodeid) { struct page *page; void *addr; int i; flags |= cachep->gfpflags; if (likely(nodeid == -1)) { page = alloc_pages(flags, cachep->gfporder); } else { page = alloc_pages_node(nodeid, flags, cachep->gfporder); } if (!page) return NULL; addr = page_address(page); i = (1 << cachep->gfporder); if (cachep->flags & SLAB_RECLAIM_ACCOUNT) atomic_add(i, &slab_reclaim_pages); add_page_state(nr_slab, i); while (i--) { SetPageSlab(page); page++; } return addr; } /* * Interface to system's page release. */ static void kmem_freepages(kmem_cache_t *cachep, void *addr) { unsigned long i = (1<<cachep->gfporder); struct page *page = virt_to_page(addr); const unsigned long nr_freed = i; while (i--) { if (!TestClearPageSlab(page)) BUG(); page++; } sub_page_state(nr_slab, nr_freed); if (current->reclaim_state) current->reclaim_state->reclaimed_slab += nr_freed; free_pages((unsigned long)addr, cachep->gfporder); if (cachep->flags & SLAB_RECLAIM_ACCOUNT) atomic_sub(1<<cachep->gfporder, &slab_reclaim_pages); } static void kmem_rcu_free(struct rcu_head *head) { struct slab_rcu *slab_rcu = (struct slab_rcu *) head; kmem_cache_t *cachep = slab_rcu->cachep; kmem_freepages(cachep, slab_rcu->addr); if (OFF_SLAB(cachep)) kmem_cache_free(cachep->slabp_cache, slab_rcu); } #if DEBUG #ifdef CONFIG_DEBUG_PAGEALLOC static void store_stackinfo(kmem_cache_t *cachep, unsigned long *addr, unsigned long caller) { int size = obj_reallen(cachep); addr = (unsigned long *)&((char*)addr)[obj_dbghead(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(kmem_cache_t *cachep, void *addr, unsigned char val) { int size = obj_reallen(cachep); addr = &((char*)addr)[obj_dbghead(cachep)]; memset(addr, val, size); *(unsigned char *)(addr+size-1) = POISON_END; } static void dump_line(char *data, int offset, int limit) { int i; printk(KERN_ERR "%03x:", offset); for (i=0;i<limit;i++) { printk(" %02x", (unsigned char)data[offset+i]); } printk("\n"); } #endif #if DEBUG static void print_objinfo(kmem_cache_t *cachep, void *objp, int lines) { int i, size; char *realobj; if (cachep->flags & SLAB_RED_ZONE) { printk(KERN_ERR "Redzone: 0x%lx/0x%lx.\n", *dbg_redzone1(cachep, objp), *dbg_redzone2(cachep, objp)); } if (cachep->flags & SLAB_STORE_USER) { printk(KERN_ERR "Last user: [<%p>]", *dbg_userword(cachep, objp)); print_symbol("(%s)", (unsigned long)*dbg_userword(cachep, objp)); printk("\n"); } realobj = (char*)objp+obj_dbghead(cachep); size = obj_reallen(cachep); 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(kmem_cache_t *cachep, void *objp) { char *realobj; int size, i; int lines = 0; realobj = (char*)objp+obj_dbghead(cachep); size = obj_reallen(cachep); 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: start=%p, len=%d\n", realobj, size); print_objinfo(cachep, objp, 0); } /* Hexdump the affected line */ i = (i/16)*16; limit = 16; if (i+limit > size) limit = size-i; dump_line(realobj, i, limit); i += 16; lines++; /* Limit to 5 lines */ if (lines > 5) break; } } if (lines != 0) { /* Print some data about the neighboring objects, if they * exist: */ struct slab *slabp = GET_PAGE_SLAB(virt_to_page(objp)); int objnr; objnr = (objp-slabp->s_mem)/cachep->objsize; if (objnr) { objp = slabp->s_mem+(objnr-1)*cachep->objsize; realobj = (char*)objp+obj_dbghead(cachep); printk(KERN_ERR "Prev obj: start=%p, len=%d\n", realobj, size); print_objinfo(cachep, objp, 2); } if (objnr+1 < cachep->num) { objp = slabp->s_mem+(objnr+1)*cachep->objsize; realobj = (char*)objp+obj_dbghead(cachep); printk(KERN_ERR "Next obj: start=%p, len=%d\n", realobj, size); print_objinfo(cachep, objp, 2); } } } #endif /* Destroy all the objs in a slab, and release the mem back to the system. * Before calling the slab must have been unlinked from the cache. * The cache-lock is not held/needed. */ static void slab_destroy (kmem_cache_t *cachep, struct slab *slabp) { void *addr = slabp->s_mem - slabp->colouroff; #if DEBUG int i; for (i = 0; i < cachep->num; i++) { void *objp = slabp->s_mem + cachep->objsize * i; if (cachep->flags & SLAB_POISON) { #ifdef CONFIG_DEBUG_PAGEALLOC if ((cachep->objsize%PAGE_SIZE)==0 && OFF_SLAB(cachep)) kernel_map_pages(virt_to_page(objp), cachep->objsize/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"); } if (cachep->dtor && !(cachep->flags & SLAB_POISON)) (cachep->dtor)(objp+obj_dbghead(cachep), cachep, 0); } #else if (cachep->dtor) { int i; for (i = 0; i < cachep->num; i++) { void* objp = slabp->s_mem+cachep->objsize*i; (cachep->dtor)(objp, cachep, 0); } } #endif if (unlikely(cachep->flags & SLAB_DESTROY_BY_RCU)) { struct slab_rcu *slab_rcu; slab_rcu = (struct slab_rcu *) slabp; slab_rcu->cachep = cachep; slab_rcu->addr = addr; call_rcu(&slab_rcu->head, kmem_rcu_free); } else { kmem_freepages(cachep, addr); if (OFF_SLAB(cachep)) kmem_cache_free(cachep->slabp_cache, slabp); } } /** * kmem_cache_create - Create a cache. * @name: A string which is used in /proc/slabinfo to identify this cache. * @size: The size of objects to be created in this cache. * @align: The required alignment for the objects. * @flags: SLAB flags * @ctor: A constructor for the objects. * @dtor: A destructor for the objects. * * 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 * and the @dtor is run before the pages are handed back. * * @name must be valid until the cache is destroyed. This implies that * the module calling this has to destroy the cache before getting * unloaded. * * 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_NO_REAP - Don't automatically reap this cache when we're under * memory pressure. * * %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. */ kmem_cache_t * kmem_cache_create (const char *name, size_t size, size_t align, unsigned long flags, void (*ctor)(void*, kmem_cache_t *, unsigned long), void (*dtor)(void*, kmem_cache_t *, unsigned long)) { size_t left_over, slab_size, ralign; kmem_cache_t *cachep = NULL; /* * Sanity checks... these are all serious usage bugs. */ if ((!name) || in_interrupt() || (size < BYTES_PER_WORD) || (size > (1<<MAX_OBJ_ORDER)*PAGE_SIZE) || (dtor && !ctor)) { printk(KERN_ERR "%s: Early error in slab %s\n", __FUNCTION__, name); BUG(); } #if DEBUG WARN_ON(strchr(name, ' ')); /* It confuses parsers */ if ((flags & SLAB_DEBUG_INITIAL) && !ctor) { /* No constructor, but inital state check requested */ printk(KERN_ERR "%s: No con, but init state check " "requested - %s\n", __FUNCTION__, name); flags &= ~SLAB_DEBUG_INITIAL; } #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+3*BYTES_PER_WORD))) 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 if (flags & SLAB_DESTROY_BY_RCU) BUG_ON(dtor); /* * Always checks flags, a caller might be expecting debug * support which isn't available. */ if (flags & ~CREATE_MASK) BUG(); /* 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); } /* calculate out the final buffer alignment: */ /* 1) arch recommendation: can be overridden for debug */ if (flags & SLAB_HWCACHE_ALIGN) { /* Default alignment: as specified by the arch code. * Except if an object is really small, then squeeze multiple * objects into one cacheline. */ ralign = cache_line_size(); while (size <= ralign/2) ralign /= 2; } else { ralign = BYTES_PER_WORD; } /* 2) arch mandated alignment: disables debug if necessary */ if (ralign < ARCH_SLAB_MINALIGN) { ralign = ARCH_SLAB_MINALIGN; if (ralign > BYTES_PER_WORD) flags &= ~(SLAB_RED_ZONE|SLAB_STORE_USER); } /* 3) caller mandated alignment: disables debug if necessary */ if (ralign < align) { ralign = align; if (ralign > BYTES_PER_WORD) flags &= ~(SLAB_RED_ZONE|SLAB_STORE_USER); } /* 4) Store it. Note that the debug code below can reduce * the alignment to BYTES_PER_WORD. */ align = ralign; /* Get cache's description obj. */ cachep = (kmem_cache_t *) kmem_cache_alloc(&cache_cache, SLAB_KERNEL); if (!cachep) goto opps; memset(cachep, 0, sizeof(kmem_cache_t)); #if DEBUG cachep->reallen = size; if (flags & SLAB_RED_ZONE) { /* redzoning only works with word aligned caches */ align = BYTES_PER_WORD; /* add space for red zone words */ cachep->dbghead += BYTES_PER_WORD; size += 2*BYTES_PER_WORD; } if (flags & SLAB_STORE_USER) { /* user store requires word alignment and * one word storage behind the end of the real * object. */ align = BYTES_PER_WORD; size += BYTES_PER_WORD; } #if FORCED_DEBUG && defined(CONFIG_DEBUG_PAGEALLOC) if (size > 128 && cachep->reallen > cache_line_size() && size < PAGE_SIZE) { cachep->dbghead += PAGE_SIZE - size; size = PAGE_SIZE; } #endif #endif /* Determine if the slab management is 'on' or 'off' slab. */ if (size >= (PAGE_SIZE>>3)) /* * 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, align); if ((flags & SLAB_RECLAIM_ACCOUNT) && size <= PAGE_SIZE) { /* * 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. */ cachep->gfporder = 0; cache_estimate(cachep->gfporder, size, align, flags, &left_over, &cachep->num); } else { /* * Calculate size (in pages) of slabs, and the num of objs per * slab. This could be made much more intelligent. For now, * try to avoid using high page-orders for slabs. When the * gfp() funcs are more friendly towards high-order requests, * this should be changed. */ do { unsigned int break_flag = 0; cal_wastage: cache_estimate(cachep->gfporder, size, align, flags, &left_over, &cachep->num); if (break_flag) break; if (cachep->gfporder >= MAX_GFP_ORDER) break; if (!cachep->num) goto next; if (flags & CFLGS_OFF_SLAB && cachep->num > offslab_limit) { /* This num of objs will cause problems. */ cachep->gfporder--; break_flag++; goto cal_wastage; } /* * Large num of objs is good, but v. large slabs are * currently bad for the gfp()s. */ if (cachep->gfporder >= slab_break_gfp_order) break; if ((left_over*8) <= (PAGE_SIZE<<cachep->gfporder)) break; /* Acceptable internal fragmentation. */ next: cachep->gfporder++; } while (1); } if (!cachep->num) { printk("kmem_cache_create: couldn't create cache %s.\n", name); kmem_cache_free(&cache_cache, cachep); cachep = NULL; goto opps; } slab_size = ALIGN(cachep->num*sizeof(kmem_bufctl_t) + sizeof(struct slab), 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 >= slab_size) { flags &= ~CFLGS_OFF_SLAB; left_over -= slab_size; } if (flags & CFLGS_OFF_SLAB) { /* really off slab. No need for manual alignment */ slab_size = cachep->num*sizeof(kmem_bufctl_t)+sizeof(struct slab); } cachep->colour_off = cache_line_size(); /* Offset must be a multiple of the alignment. */ if (cachep->colour_off < align) cachep->colour_off = align; cachep->colour = left_over/cachep->colour_off; cachep->slab_size = slab_size; cachep->flags = flags; cachep->gfpflags = 0; if (flags & SLAB_CACHE_DMA) cachep->gfpflags |= GFP_DMA; spin_lock_init(&cachep->spinlock); cachep->objsize = size; /* NUMA */ INIT_LIST_HEAD(&cachep->lists.slabs_full); INIT_LIST_HEAD(&cachep->lists.slabs_partial); INIT_LIST_HEAD(&cachep->lists.slabs_free); if (flags & CFLGS_OFF_SLAB) cachep->slabp_cache = kmem_find_general_cachep(slab_size,0); cachep->ctor = ctor; cachep->dtor = dtor; cachep->name = name; /* Don't let CPUs to come and go */ lock_cpu_hotplug(); if (g_cpucache_up == FULL) { enable_cpucache(cachep); } else { if (g_cpucache_up == NONE) { /* Note: the first kmem_cache_create must create * the cache that's used by kmalloc(24), otherwise * the creation of further caches will BUG(). */ cachep->array[smp_processor_id()] = &initarray_generic.cache; g_cpucache_up = PARTIAL; } else { cachep->array[smp_processor_id()] = kmalloc(sizeof(struct arraycache_init),GFP_KERNEL); } BUG_ON(!ac_data(cachep)); ac_data(cachep)->avail = 0; ac_data(cachep)->limit = BOOT_CPUCACHE_ENTRIES; ac_data(cachep)->batchcount = 1; ac_data(cachep)->touched = 0; cachep->batchcount = 1; cachep->limit = BOOT_CPUCACHE_ENTRIES; cachep->free_limit = (1+num_online_cpus())*cachep->batchcount + cachep->num; } cachep->lists.next_reap = jiffies + REAPTIMEOUT_LIST3 + ((unsigned long)cachep)%REAPTIMEOUT_LIST3; /* Need the semaphore to access the chain. */ down(&cache_chain_sem); { struct list_head *p; mm_segment_t old_fs; old_fs = get_fs(); set_fs(KERNEL_DS); list_for_each(p, &cache_chain) { kmem_cache_t *pc = list_entry(p, kmem_cache_t, next); char tmp; /* This happens when the module gets unloaded and doesn't destroy its slab cache and noone else reuses the vmalloc area of the module. Print a warning. */ if (__get_user(tmp,pc->name)) { printk("SLAB: cache with size %d has lost its name\n", pc->objsize); continue; } if (!strcmp(pc->name,name)) { printk("kmem_cache_create: duplicate cache %s\n",name); up(&cache_chain_sem); unlock_cpu_hotplug(); BUG(); } } set_fs(old_fs); } /* cache setup completed, link it into the list */ list_add(&cachep->next, &cache_chain); up(&cache_chain_sem); unlock_cpu_hotplug(); opps: if (!cachep && (flags & SLAB_PANIC)) panic("kmem_cache_create(): failed to create slab `%s'\n", name); return cachep; } EXPORT_SYMBOL(kmem_cache_create); #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(kmem_cache_t *cachep) { #ifdef CONFIG_SMP check_irq_off(); BUG_ON(spin_trylock(&cachep->spinlock)); #endif } #else #define check_irq_off() do { } while(0) #define check_irq_on() do { } while(0) #define check_spinlock_acquired(x) do { } while(0) #endif /* * Waits for all CPUs to execute func(). */ static void smp_call_function_all_cpus(void (*func) (void *arg), void *arg) { check_irq_on(); preempt_disable(); local_irq_disable(); func(arg); local_irq_enable(); if (smp_call_function(func, arg, 1, 1)) BUG(); preempt_enable(); } static void drain_array_locked(kmem_cache_t* cachep, struct array_cache *ac, int force); static void do_drain(void *arg) { kmem_cache_t *cachep = (kmem_cache_t*)arg; struct array_cache *ac; check_irq_off(); ac = ac_data(cachep); spin_lock(&cachep->spinlock); free_block(cachep, &ac_entry(ac)[0], ac->avail); spin_unlock(&cachep->spinlock); ac->avail = 0; } static void drain_cpu_caches(kmem_cache_t *cachep) { smp_call_function_all_cpus(do_drain, cachep); check_irq_on(); spin_lock_irq(&cachep->spinlock); if (cachep->lists.shared) drain_array_locked(cachep, cachep->lists.shared, 1); spin_unlock_irq(&cachep->spinlock); } /* NUMA shrink all list3s */ static int __cache_shrink(kmem_cache_t *cachep) { struct slab *slabp; int ret; drain_cpu_caches(cachep); check_irq_on(); spin_lock_irq(&cachep->spinlock); for(;;) { struct list_head *p; p = cachep->lists.slabs_free.prev; if (p == &cachep->lists.slabs_free) break; slabp = list_entry(cachep->lists.slabs_free.prev, struct slab, list); #if DEBUG if (slabp->inuse) BUG(); #endif list_del(&slabp->list); cachep->lists.free_objects -= cachep->num; spin_unlock_irq(&cachep->spinlock); slab_destroy(cachep, slabp); spin_lock_irq(&cachep->spinlock); } ret = !list_empty(&cachep->lists.slabs_full) || !list_empty(&cachep->lists.slabs_partial); spin_unlock_irq(&cachep->spinlock); return ret; } /** * kmem_cache_shrink - Shrink a cache. * @cachep: The cache to shrink. * * Releases as many slabs as possible for a cache. * To help debugging, a zero exit status indicates all slabs were released. */ int kmem_cache_shrink(kmem_cache_t *cachep) { if (!cachep || in_interrupt()) BUG(); return __cache_shrink(cachep); } EXPORT_SYMBOL(kmem_cache_shrink); /** * kmem_cache_destroy - delete a cache * @cachep: the cache to destroy * * Remove a kmem_cache_t object from the slab cache. * Returns 0 on success. * * It is expected this function will be called by a module when it is * unloaded. This will remove the cache completely, and avoid a duplicate * cache being allocated each time a module is loaded and unloaded, if the * module doesn't have persistent in-kernel storage across loads and unloads. * * The cache must be empty before calling this function. * * The caller must guarantee that noone will allocate memory from the cache * during the kmem_cache_destroy(). */ int kmem_cache_destroy(kmem_cache_t * cachep) { int i; if (!cachep || in_interrupt()) BUG(); /* Don't let CPUs to come and go */ lock_cpu_hotplug(); /* Find the cache in the chain of caches. */ down(&cache_chain_sem); /* * the chain is never empty, cache_cache is never destroyed */ list_del(&cachep->next); up(&cache_chain_sem); if (__cache_shrink(cachep)) { slab_error(cachep, "Can't free all objects"); down(&cache_chain_sem); list_add(&cachep->next,&cache_chain); up(&cache_chain_sem); unlock_cpu_hotplug(); return 1; } if (unlikely(cachep->flags & SLAB_DESTROY_BY_RCU)) synchronize_rcu(); /* no cpu_online check required here since we clear the percpu * array on cpu offline and set this to NULL. */ for (i = 0; i < NR_CPUS; i++) kfree(cachep->array[i]); /* NUMA: free the list3 structures */ kfree(cachep->lists.shared); cachep->lists.shared = NULL; kmem_cache_free(&cache_cache, cachep); unlock_cpu_hotplug(); return 0; } EXPORT_SYMBOL(kmem_cache_destroy); /* Get the memory for a slab management obj. */ static struct slab* alloc_slabmgmt(kmem_cache_t *cachep, void *objp, int colour_off, unsigned int __nocast local_flags) { struct slab *slabp; if (OFF_SLAB(cachep)) { /* Slab management obj is off-slab. */ slabp = kmem_cache_alloc(cachep->slabp_cache, local_flags); if (!slabp) return NULL; } else { slabp = objp+colour_off; colour_off += cachep->slab_size; } slabp->inuse = 0; slabp->colouroff = colour_off; slabp->s_mem = objp+colour_off; return slabp; } static inline kmem_bufctl_t *slab_bufctl(struct slab *slabp) { return (kmem_bufctl_t *)(slabp+1); } static void cache_init_objs(kmem_cache_t *cachep, struct slab *slabp, unsigned long ctor_flags) { int i; for (i = 0; i < cachep->num; i++) { void* objp = slabp->s_mem+cachep->objsize*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_dbghead(cachep), cachep, ctor_flags); 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->objsize % PAGE_SIZE) == 0 && OFF_SLAB(cachep) && cachep->flags & SLAB_POISON) kernel_map_pages(virt_to_page(objp), cachep->objsize/PAGE_SIZE, 0); #else if (cachep->ctor) cachep->ctor(objp, cachep, ctor_flags); #endif slab_bufctl(slabp)[i] = i+1; } slab_bufctl(slabp)[i-1] = BUFCTL_END; slabp->free = 0; } static void kmem_flagcheck(kmem_cache_t *cachep, unsigned int flags) { if (flags & SLAB_DMA) { if (!(cachep->gfpflags & GFP_DMA)) BUG(); } else { if (cachep->gfpflags & GFP_DMA) BUG(); } } static void set_slab_attr(kmem_cache_t *cachep, struct slab *slabp, void *objp) { int i; struct page *page; /* Nasty!!!!!! I hope this is OK. */ i = 1 << cachep->gfporder; page = virt_to_page(objp); do { SET_PAGE_CACHE(page, cachep); SET_PAGE_SLAB(page, slabp); page++; } while (--i); } /* * 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(kmem_cache_t *cachep, unsigned int __nocast flags, int nodeid) { struct slab *slabp; void *objp; size_t offset; unsigned int local_flags; unsigned long ctor_flags; /* Be lazy and only check for valid flags here, * keeping it out of the critical path in kmem_cache_alloc(). */ if (flags & ~(SLAB_DMA|SLAB_LEVEL_MASK|SLAB_NO_GROW)) BUG(); if (flags & SLAB_NO_GROW) return 0; ctor_flags = SLAB_CTOR_CONSTRUCTOR; local_flags = (flags & SLAB_LEVEL_MASK); if (!(local_flags & __GFP_WAIT)) /* * Not allowed to sleep. Need to tell a constructor about * this - it might need to know... */ ctor_flags |= SLAB_CTOR_ATOMIC; /* About to mess with non-constant members - lock. */ check_irq_off(); spin_lock(&cachep->spinlock); /* Get colour for the slab, and cal the next value. */ offset = cachep->colour_next; cachep->colour_next++; if (cachep->colour_next >= cachep->colour) cachep->colour_next = 0; offset *= cachep->colour_off; spin_unlock(&cachep->spinlock); 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. */ if (!(objp = kmem_getpages(cachep, flags, nodeid))) goto failed; /* Get slab management. */ if (!(slabp = alloc_slabmgmt(cachep, objp, offset, local_flags))) goto opps1; set_slab_attr(cachep, slabp, objp); cache_init_objs(cachep, slabp, ctor_flags); if (local_flags & __GFP_WAIT) local_irq_disable(); check_irq_off(); spin_lock(&cachep->spinlock); /* Make slab active. */ list_add_tail(&slabp->list, &(list3_data(cachep)->slabs_free)); STATS_INC_GROWN(cachep); list3_data(cachep)->free_objects += cachep->num; spin_unlock(&cachep->spinlock); return 1; opps1: kmem_freepages(cachep, objp); failed: if (local_flags & __GFP_WAIT) local_irq_disable(); return 0; } #if DEBUG /* * Perform extra freeing checks: * - detect bad pointers. * - POISON/RED_ZONE checking * - destructor calls, for caches with POISON+dtor */ static void kfree_debugcheck(const void *objp) { struct page *page; if (!virt_addr_valid(objp)) { printk(KERN_ERR "kfree_debugcheck: out of range ptr %lxh.\n", (unsigned long)objp); BUG(); } page = virt_to_page(objp); if (!PageSlab(page)) { printk(KERN_ERR "kfree_debugcheck: bad ptr %lxh.\n", (unsigned long)objp); BUG(); } } static void *cache_free_debugcheck(kmem_cache_t *cachep, void *objp, void *caller) { struct page *page; unsigned int objnr; struct slab *slabp; objp -= obj_dbghead(cachep); kfree_debugcheck(objp); page = virt_to_page(objp); if (GET_PAGE_CACHE(page) != cachep) { printk(KERN_ERR "mismatch in kmem_cache_free: expected cache %p, got %p\n", GET_PAGE_CACHE(page),cachep); printk(KERN_ERR "%p is %s.\n", cachep, cachep->name); printk(KERN_ERR "%p is %s.\n", GET_PAGE_CACHE(page), GET_PAGE_CACHE(page)->name); WARN_ON(1); } slabp = GET_PAGE_SLAB(page); if (cachep->flags & SLAB_RED_ZONE) { if (*dbg_redzone1(cachep, objp) != RED_ACTIVE || *dbg_redzone2(cachep, objp) != RED_ACTIVE) { slab_error(cachep, "double free, or memory outside" " object was overwritten"); printk(KERN_ERR "%p: redzone 1: 0x%lx, redzone 2: 0x%lx.\n", objp, *dbg_redzone1(cachep, objp), *dbg_redzone2(cachep, objp)); } *dbg_redzone1(cachep, objp) = RED_INACTIVE; *dbg_redzone2(cachep, objp) = RED_INACTIVE; } if (cachep->flags & SLAB_STORE_USER) *dbg_userword(cachep, objp) = caller; objnr = (objp-slabp->s_mem)/cachep->objsize; BUG_ON(objnr >= cachep->num); BUG_ON(objp != slabp->s_mem + objnr*cachep->objsize); if (cachep->flags & SLAB_DEBUG_INITIAL) { /* Need to call the slab's constructor so the * caller can perform a verify of its state (debugging). * Called without the cache-lock held. */ cachep->ctor(objp+obj_dbghead(cachep), cachep, SLAB_CTOR_CONSTRUCTOR|SLAB_CTOR_VERIFY); } if (cachep->flags & SLAB_POISON && cachep->dtor) { /* we want to cache poison the object, * call the destruction callback */ cachep->dtor(objp+obj_dbghead(cachep), cachep, 0); } if (cachep->flags & SLAB_POISON) { #ifdef CONFIG_DEBUG_PAGEALLOC if ((cachep->objsize % PAGE_SIZE) == 0 && OFF_SLAB(cachep)) { store_stackinfo(cachep, objp, (unsigned long)caller); kernel_map_pages(virt_to_page(objp), cachep->objsize/PAGE_SIZE, 0); } else { poison_obj(cachep, objp, POISON_FREE); } #else poison_obj(cachep, objp, POISON_FREE); #endif } return objp; } static void check_slabp(kmem_cache_t *cachep, struct slab *slabp) { kmem_bufctl_t i; int entries = 0; check_spinlock_acquired(cachep); /* Check slab's freelist to see if this obj is there. */ for (i = slabp->free; i != BUFCTL_END; i = slab_bufctl(slabp)[i]) { entries++; if (entries > cachep->num || i >= cachep->num) goto bad; } if (entries != cachep->num - slabp->inuse) { bad: printk(KERN_ERR "slab: Internal list corruption detected in cache '%s'(%d), slabp %p(%d). Hexdump:\n", cachep->name, cachep->num, slabp, slabp->inuse); for (i=0;i<sizeof(slabp)+cachep->num*sizeof(kmem_bufctl_t);i++) { if ((i%16)==0) printk("\n%03x:", i); printk(" %02x", ((unsigned char*)slabp)[i]); } printk("\n"); BUG(); } } #else #define kfree_debugcheck(x) do { } while(0) #define cache_free_debugcheck(x,objp,z) (objp) #define check_slabp(x,y) do { } while(0) #endif static void *cache_alloc_refill(kmem_cache_t *cachep, unsigned int __nocast flags) { int batchcount; struct kmem_list3 *l3; struct array_cache *ac; check_irq_off(); ac = ac_data(cachep); retry: 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; } l3 = list3_data(cachep); BUG_ON(ac->avail > 0); spin_lock(&cachep->spinlock); if (l3->shared) { struct array_cache *shared_array = l3->shared; if (shared_array->avail) { if (batchcount > shared_array->avail) batchcount = shared_array->avail; shared_array->avail -= batchcount; ac->avail = batchcount; memcpy(ac_entry(ac), &ac_entry(shared_array)[shared_array->avail], sizeof(void*)*batchcount); shared_array->touched = 1; goto alloc_done; } } while (batchcount > 0) { struct list_head *entry; struct slab *slabp; /* Get slab alloc is to come from. */ entry = l3->slabs_partial.next; if (entry == &l3->slabs_partial) { l3->free_touched = 1; entry = l3->slabs_free.next; if (entry == &l3->slabs_free) goto must_grow; } slabp = list_entry(entry, struct slab, list); check_slabp(cachep, slabp); check_spinlock_acquired(cachep); while (slabp->inuse < cachep->num && batchcount--) { kmem_bufctl_t next; STATS_INC_ALLOCED(cachep); STATS_INC_ACTIVE(cachep); STATS_SET_HIGH(cachep); /* get obj pointer */ ac_entry(ac)[ac->avail++] = slabp->s_mem + slabp->free*cachep->objsize; slabp->inuse++; next = slab_bufctl(slabp)[slabp->free]; #if DEBUG slab_bufctl(slabp)[slabp->free] = BUFCTL_FREE; #endif slabp->free = next; } check_slabp(cachep, slabp); /* move slabp to correct slabp list: */ list_del(&slabp->list); if (slabp->free == BUFCTL_END) list_add(&slabp->list, &l3->slabs_full); else list_add(&slabp->list, &l3->slabs_partial); } must_grow: l3->free_objects -= ac->avail; alloc_done: spin_unlock(&cachep->spinlock); if (unlikely(!ac->avail)) { int x; x = cache_grow(cachep, flags, -1); // cache_grow can reenable interrupts, then ac could change. ac = ac_data(cachep); if (!x && ac->avail == 0) // no objects in sight? abort return NULL; if (!ac->avail) // objects refilled by interrupt? goto retry; } ac->touched = 1; return ac_entry(ac)[--ac->avail]; } static inline void cache_alloc_debugcheck_before(kmem_cache_t *cachep, unsigned int __nocast flags) { might_sleep_if(flags & __GFP_WAIT); #if DEBUG kmem_flagcheck(cachep, flags); #endif } #if DEBUG static void * cache_alloc_debugcheck_after(kmem_cache_t *cachep, unsigned int __nocast flags, void *objp, void *caller) { if (!objp) return objp; if (cachep->flags & SLAB_POISON) { #ifdef CONFIG_DEBUG_PAGEALLOC if ((cachep->objsize % PAGE_SIZE) == 0 && OFF_SLAB(cachep)) kernel_map_pages(virt_to_page(objp), cachep->objsize/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) = 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%lx, redzone 2: 0x%lx.\n", objp, *dbg_redzone1(cachep, objp), *dbg_redzone2(cachep, objp)); } *dbg_redzone1(cachep, objp) = RED_ACTIVE; *dbg_redzone2(cachep, objp) = RED_ACTIVE; } objp += obj_dbghead(cachep); if (cachep->ctor && cachep->flags & SLAB_POISON) { unsigned long ctor_flags = SLAB_CTOR_CONSTRUCTOR; if (!(flags & __GFP_WAIT)) ctor_flags |= SLAB_CTOR_ATOMIC; cachep->ctor(objp, cachep, ctor_flags); } return objp; } #else #define cache_alloc_debugcheck_after(a,b,objp,d) (objp) #endif static inline void *__cache_alloc(kmem_cache_t *cachep, unsigned int __nocast flags) { unsigned long save_flags; void* objp; struct array_cache *ac; cache_alloc_debugcheck_before(cachep, flags); local_irq_save(save_flags); ac = ac_data(cachep); if (likely(ac->avail)) { STATS_INC_ALLOCHIT(cachep); ac->touched = 1; objp = ac_entry(ac)[--ac->avail]; } else { STATS_INC_ALLOCMISS(cachep); objp = cache_alloc_refill(cachep, flags); } local_irq_restore(save_flags); objp = cache_alloc_debugcheck_after(cachep, flags, objp, __builtin_return_address(0)); return objp; } /* * NUMA: different approach needed if the spinlock is moved into * the l3 structure */ static void free_block(kmem_cache_t *cachep, void **objpp, int nr_objects) { int i; check_spinlock_acquired(cachep); /* NUMA: move add into loop */ cachep->lists.free_objects += nr_objects; for (i = 0; i < nr_objects; i++) { void *objp = objpp[i]; struct slab *slabp; unsigned int objnr; slabp = GET_PAGE_SLAB(virt_to_page(objp)); list_del(&slabp->list); objnr = (objp - slabp->s_mem) / cachep->objsize; check_slabp(cachep, slabp); #if DEBUG if (slab_bufctl(slabp)[objnr] != BUFCTL_FREE) { printk(KERN_ERR "slab: double free detected in cache '%s', objp %p.\n", cachep->name, objp); BUG(); } #endif slab_bufctl(slabp)[objnr] = slabp->free; slabp->free = objnr; STATS_DEC_ACTIVE(cachep); slabp->inuse--; check_slabp(cachep, slabp); /* fixup slab chains */ if (slabp->inuse == 0) { if (cachep->lists.free_objects > cachep->free_limit) { cachep->lists.free_objects -= cachep->num; slab_destroy(cachep, slabp); } else { list_add(&slabp->list, &list3_data_ptr(cachep, objp)->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(&slabp->list, &list3_data_ptr(cachep, objp)->slabs_partial); } } } static void cache_flusharray(kmem_cache_t *cachep, struct array_cache *ac) { int batchcount; batchcount = ac->batchcount; #if DEBUG BUG_ON(!batchcount || batchcount > ac->avail); #endif check_irq_off(); spin_lock(&cachep->spinlock); if (cachep->lists.shared) { struct array_cache *shared_array = cachep->lists.shared; int max = shared_array->limit-shared_array->avail; if (max) { if (batchcount > max) batchcount = max; memcpy(&ac_entry(shared_array)[shared_array->avail], &ac_entry(ac)[0], sizeof(void*)*batchcount); shared_array->avail += batchcount; goto free_done; } } free_block(cachep, &ac_entry(ac)[0], batchcount); free_done: #if STATS { int i = 0; struct list_head *p; p = list3_data(cachep)->slabs_free.next; while (p != &(list3_data(cachep)->slabs_free)) { struct slab *slabp; slabp = list_entry(p, struct slab, list); BUG_ON(slabp->inuse); i++; p = p->next; } STATS_SET_FREEABLE(cachep, i); } #endif spin_unlock(&cachep->spinlock); ac->avail -= batchcount; memmove(&ac_entry(ac)[0], &ac_entry(ac)[batchcount], sizeof(void*)*ac->avail); } /* * __cache_free * 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(kmem_cache_t *cachep, void *objp) { struct array_cache *ac = ac_data(cachep); check_irq_off(); objp = cache_free_debugcheck(cachep, objp, __builtin_return_address(0)); if (likely(ac->avail < ac->limit)) { STATS_INC_FREEHIT(cachep); ac_entry(ac)[ac->avail++] = objp; return; } else { STATS_INC_FREEMISS(cachep); cache_flusharray(cachep, ac); ac_entry(ac)[ac->avail++] = 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(kmem_cache_t *cachep, unsigned int __nocast flags) { return __cache_alloc(cachep, flags); } EXPORT_SYMBOL(kmem_cache_alloc); /** * kmem_ptr_validate - check if an untrusted pointer might * be a slab entry. * @cachep: the cache we're checking against * @ptr: pointer to validate * * This verifies that the untrusted pointer looks sane: * it is _not_ a guarantee that the pointer is actually * part of the slab cache in question, but it at least * validates that the pointer can be dereferenced and * looks half-way sane. * * Currently only used for dentry validation. */ int fastcall kmem_ptr_validate(kmem_cache_t *cachep, void *ptr) { unsigned long addr = (unsigned long) ptr; unsigned long min_addr = PAGE_OFFSET; unsigned long align_mask = BYTES_PER_WORD-1; unsigned long size = cachep->objsize; struct page *page; if (unlikely(addr < min_addr)) goto out; if (unlikely(addr > (unsigned long)high_memory - size)) goto out; if (unlikely(addr & align_mask)) goto out; if (unlikely(!kern_addr_valid(addr))) goto out; if (unlikely(!kern_addr_valid(addr + size - 1))) goto out; page = virt_to_page(ptr); if (unlikely(!PageSlab(page))) goto out; if (unlikely(GET_PAGE_CACHE(page) != cachep)) goto out; return 1; out: return 0; } #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, except that this function is slow * and can sleep. And it will allocate memory on the given node, which * can improve the performance for cpu bound structures. */ void *kmem_cache_alloc_node(kmem_cache_t *cachep, int flags, int nodeid) { int loop; void *objp; struct slab *slabp; kmem_bufctl_t next; if (nodeid == -1) return kmem_cache_alloc(cachep, flags); for (loop = 0;;loop++) { struct list_head *q; objp = NULL; check_irq_on(); spin_lock_irq(&cachep->spinlock); /* walk through all partial and empty slab and find one * from the right node */ list_for_each(q,&cachep->lists.slabs_partial) { slabp = list_entry(q, struct slab, list); if (page_to_nid(virt_to_page(slabp->s_mem)) == nodeid || loop > 2) goto got_slabp; } list_for_each(q, &cachep->lists.slabs_free) { slabp = list_entry(q, struct slab, list); if (page_to_nid(virt_to_page(slabp->s_mem)) == nodeid || loop > 2) goto got_slabp; } spin_unlock_irq(&cachep->spinlock); local_irq_disable(); if (!cache_grow(cachep, flags, nodeid)) { local_irq_enable(); return NULL; } local_irq_enable(); } got_slabp: /* found one: allocate object */ check_slabp(cachep, slabp); check_spinlock_acquired(cachep); STATS_INC_ALLOCED(cachep); STATS_INC_ACTIVE(cachep); STATS_SET_HIGH(cachep); STATS_INC_NODEALLOCS(cachep); objp = slabp->s_mem + slabp->free*cachep->objsize; slabp->inuse++; next = slab_bufctl(slabp)[slabp->free]; #if DEBUG slab_bufctl(slabp)[slabp->free] = BUFCTL_FREE; #endif slabp->free = next; check_slabp(cachep, slabp); /* move slabp to correct slabp list: */ list_del(&slabp->list); if (slabp->free == BUFCTL_END) list_add(&slabp->list, &cachep->lists.slabs_full); else list_add(&slabp->list, &cachep->lists.slabs_partial); list3_data(cachep)->free_objects--; spin_unlock_irq(&cachep->spinlock); objp = cache_alloc_debugcheck_after(cachep, GFP_KERNEL, objp, __builtin_return_address(0)); return objp; } EXPORT_SYMBOL(kmem_cache_alloc_node); void *kmalloc_node(size_t size, unsigned int __nocast flags, int node) { kmem_cache_t *cachep; cachep = kmem_find_general_cachep(size, flags); if (unlikely(cachep == NULL)) return NULL; return kmem_cache_alloc_node(cachep, flags, node); } EXPORT_SYMBOL(kmalloc_node); #endif /** * kmalloc - allocate memory * @size: how many bytes of memory are required. * @flags: the type of memory to allocate. * * kmalloc is the normal method of allocating memory * in the kernel. * * The @flags argument may be one of: * * %GFP_USER - Allocate memory on behalf of user. May sleep. * * %GFP_KERNEL - Allocate normal kernel ram. May sleep. * * %GFP_ATOMIC - Allocation will not sleep. Use inside interrupt handlers. * * Additionally, the %GFP_DMA flag may be set to indicate the memory * must be suitable for DMA. This can mean different things on different * platforms. For example, on i386, it means that the memory must come * from the first 16MB. */ void *__kmalloc(size_t size, unsigned int __nocast flags) { kmem_cache_t *cachep; /* If you want to save a few bytes .text space: replace * __ with kmem_. * Then kmalloc uses the uninlined functions instead of the inline * functions. */ cachep = __find_general_cachep(size, flags); if (unlikely(cachep == NULL)) return NULL; return __cache_alloc(cachep, flags); } EXPORT_SYMBOL(__kmalloc); #ifdef CONFIG_SMP /** * __alloc_percpu - allocate one copy of the object for every present * cpu in the system, zeroing them. * Objects should be dereferenced using the per_cpu_ptr macro only. * * @size: how many bytes of memory are required. * @align: the alignment, which can't be greater than SMP_CACHE_BYTES. */ void *__alloc_percpu(size_t size, size_t align) { int i; struct percpu_data *pdata = kmalloc(sizeof (*pdata), GFP_KERNEL); if (!pdata) return NULL; for (i = 0; i < NR_CPUS; i++) { if (!cpu_possible(i)) continue; pdata->ptrs[i] = kmalloc_node(size, GFP_KERNEL, cpu_to_node(i)); if (!pdata->ptrs[i]) goto unwind_oom; memset(pdata->ptrs[i], 0, size); } /* Catch derefs w/o wrappers */ return (void *) (~(unsigned long) pdata); unwind_oom: while (--i >= 0) { if (!cpu_possible(i)) continue; kfree(pdata->ptrs[i]); } kfree(pdata); return NULL; } EXPORT_SYMBOL(__alloc_percpu); #endif /** * 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(kmem_cache_t *cachep, void *objp) { unsigned long flags; local_irq_save(flags); __cache_free(cachep, objp); local_irq_restore(flags); } EXPORT_SYMBOL(kmem_cache_free); /** * kcalloc - allocate memory for an array. The memory is set to zero. * @n: number of elements. * @size: element size. * @flags: the type of memory to allocate. */ void *kcalloc(size_t n, size_t size, unsigned int __nocast flags) { void *ret = NULL; if (n != 0 && size > INT_MAX / n) return ret; ret = kmalloc(n * size, flags); if (ret) memset(ret, 0, n * size); return ret; } EXPORT_SYMBOL(kcalloc); /** * kfree - free previously allocated memory * @objp: pointer returned by kmalloc. * * Don't free memory not originally allocated by kmalloc() * or you will run into trouble. */ void kfree(const void *objp) { kmem_cache_t *c; unsigned long flags; if (unlikely(!objp)) return; local_irq_save(flags); kfree_debugcheck(objp); c = GET_PAGE_CACHE(virt_to_page(objp)); __cache_free(c, (void*)objp); local_irq_restore(flags); } EXPORT_SYMBOL(kfree); #ifdef CONFIG_SMP /** * free_percpu - free previously allocated percpu memory * @objp: pointer returned by alloc_percpu. * * Don't free memory not originally allocated by alloc_percpu() * The complemented objp is to check for that. */ void free_percpu(const void *objp) { int i; struct percpu_data *p = (struct percpu_data *) (~(unsigned long) objp); for (i = 0; i < NR_CPUS; i++) { if (!cpu_possible(i)) continue; kfree(p->ptrs[i]); } kfree(p); } EXPORT_SYMBOL(free_percpu); #endif unsigned int kmem_cache_size(kmem_cache_t *cachep) { return obj_reallen(cachep); } EXPORT_SYMBOL(kmem_cache_size); const char *kmem_cache_name(kmem_cache_t *cachep) { return cachep->name; } EXPORT_SYMBOL_GPL(kmem_cache_name); struct ccupdate_struct { kmem_cache_t *cachep; struct array_cache *new[NR_CPUS]; }; static void do_ccupdate_local(void *info) { struct ccupdate_struct *new = (struct ccupdate_struct *)info; struct array_cache *old; check_irq_off(); old = ac_data(new->cachep); new->cachep->array[smp_processor_id()] = new->new[smp_processor_id()]; new->new[smp_processor_id()] = old; } static int do_tune_cpucache(kmem_cache_t *cachep, int limit, int batchcount, int shared) { struct ccupdate_struct new; struct array_cache *new_shared; int i; memset(&new.new,0,sizeof(new.new)); for (i = 0; i < NR_CPUS; i++) { if (cpu_online(i)) { new.new[i] = alloc_arraycache(i, limit, batchcount); if (!new.new[i]) { for (i--; i >= 0; i--) kfree(new.new[i]); return -ENOMEM; } } else { new.new[i] = NULL; } } new.cachep = cachep; smp_call_function_all_cpus(do_ccupdate_local, (void *)&new); check_irq_on(); spin_lock_irq(&cachep->spinlock); cachep->batchcount = batchcount; cachep->limit = limit; cachep->free_limit = (1+num_online_cpus())*cachep->batchcount + cachep->num; spin_unlock_irq(&cachep->spinlock); for (i = 0; i < NR_CPUS; i++) { struct array_cache *ccold = new.new[i]; if (!ccold) continue; spin_lock_irq(&cachep->spinlock); free_block(cachep, ac_entry(ccold), ccold->avail); spin_unlock_irq(&cachep->spinlock); kfree(ccold); } new_shared = alloc_arraycache(-1, batchcount*shared, 0xbaadf00d); if (new_shared) { struct array_cache *old; spin_lock_irq(&cachep->spinlock); old = cachep->lists.shared; cachep->lists.shared = new_shared; if (old) free_block(cachep, ac_entry(old), old->avail); spin_unlock_irq(&cachep->spinlock); kfree(old); } return 0; } static void enable_cpucache(kmem_cache_t *cachep) { int err; int limit, shared; /* 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->objsize > 131072) limit = 1; else if (cachep->objsize > PAGE_SIZE) limit = 8; else if (cachep->objsize > 1024) limit = 24; else if (cachep->objsize > 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; #ifdef CONFIG_SMP if (cachep->objsize <= PAGE_SIZE) shared = 8; #endif #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 err = do_tune_cpucache(cachep, limit, (limit+1)/2, shared); if (err) printk(KERN_ERR "enable_cpucache failed for %s, error %d.\n", cachep->name, -err); } static void drain_array_locked(kmem_cache_t *cachep, struct array_cache *ac, int force) { int tofree; check_spinlock_acquired(cachep); if (ac->touched && !force) { ac->touched = 0; } else 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(ac), tofree); ac->avail -= tofree; memmove(&ac_entry(ac)[0], &ac_entry(ac)[tofree], sizeof(void*)*ac->avail); } } /** * cache_reap - Reclaim memory from caches. * * 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 semaphore then just give up - we'll * try again on the next iteration. */ static void cache_reap(void *unused) { struct list_head *walk; if (down_trylock(&cache_chain_sem)) { /* Give up. Setup the next iteration. */ schedule_delayed_work(&__get_cpu_var(reap_work), REAPTIMEOUT_CPUC + smp_processor_id()); return; } list_for_each(walk, &cache_chain) { kmem_cache_t *searchp; struct list_head* p; int tofree; struct slab *slabp; searchp = list_entry(walk, kmem_cache_t, next); if (searchp->flags & SLAB_NO_REAP) goto next; check_irq_on(); spin_lock_irq(&searchp->spinlock); drain_array_locked(searchp, ac_data(searchp), 0); if(time_after(searchp->lists.next_reap, jiffies)) goto next_unlock; searchp->lists.next_reap = jiffies + REAPTIMEOUT_LIST3; if (searchp->lists.shared) drain_array_locked(searchp, searchp->lists.shared, 0); if (searchp->lists.free_touched) { searchp->lists.free_touched = 0; goto next_unlock; } tofree = (searchp->free_limit+5*searchp->num-1)/(5*searchp->num); do { p = list3_data(searchp)->slabs_free.next; if (p == &(list3_data(searchp)->slabs_free)) break; slabp = list_entry(p, struct slab, list); BUG_ON(slabp->inuse); list_del(&slabp->list); STATS_INC_REAPED(searchp); /* Safe to drop the lock. The slab is no longer * linked to the cache. * searchp cannot disappear, we hold * cache_chain_lock */ searchp->lists.free_objects -= searchp->num; spin_unlock_irq(&searchp->spinlock); slab_destroy(searchp, slabp); spin_lock_irq(&searchp->spinlock); } while(--tofree > 0); next_unlock: spin_unlock_irq(&searchp->spinlock); next: cond_resched(); } check_irq_on(); up(&cache_chain_sem); drain_remote_pages(); /* Setup the next iteration */ schedule_delayed_work(&__get_cpu_var(reap_work), REAPTIMEOUT_CPUC + smp_processor_id()); } #ifdef CONFIG_PROC_FS static void *s_start(struct seq_file *m, loff_t *pos) { loff_t n = *pos; struct list_head *p; down(&cache_chain_sem); if (!n) { /* * Output format version, so at least we can change it * without _too_ many complaints. */ #if STATS seq_puts(m, "slabinfo - version: 2.1 (statistics)\n"); #else seq_puts(m, "slabinfo - version: 2.1\n"); #endif seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>"); seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>"); seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>"); #if STATS seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped>" " <error> <maxfreeable> <freelimit> <nodeallocs>"); seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>"); #endif seq_putc(m, '\n'); } p = cache_chain.next; while (n--) { p = p->next; if (p == &cache_chain) return NULL; } return list_entry(p, kmem_cache_t, next); } static void *s_next(struct seq_file *m, void *p, loff_t *pos) { kmem_cache_t *cachep = p; ++*pos; return cachep->next.next == &cache_chain ? NULL : list_entry(cachep->next.next, kmem_cache_t, next); } static void s_stop(struct seq_file *m, void *p) { up(&cache_chain_sem); } static int s_show(struct seq_file *m, void *p) { kmem_cache_t *cachep = p; struct list_head *q; struct slab *slabp; unsigned long active_objs; unsigned long num_objs; unsigned long active_slabs = 0; unsigned long num_slabs; const char *name; char *error = NULL; check_irq_on(); spin_lock_irq(&cachep->spinlock); active_objs = 0; num_slabs = 0; list_for_each(q,&cachep->lists.slabs_full) { slabp = list_entry(q, struct slab, list); if (slabp->inuse != cachep->num && !error) error = "slabs_full accounting error"; active_objs += cachep->num; active_slabs++; } list_for_each(q,&cachep->lists.slabs_partial) { slabp = list_entry(q, struct slab, list); if (slabp->inuse == cachep->num && !error) error = "slabs_partial inuse accounting error"; if (!slabp->inuse && !error) error = "slabs_partial/inuse accounting error"; active_objs += slabp->inuse; active_slabs++; } list_for_each(q,&cachep->lists.slabs_free) { slabp = list_entry(q, struct slab, list); if (slabp->inuse && !error) error = "slabs_free/inuse accounting error"; num_slabs++; } num_slabs+=active_slabs; num_objs = num_slabs*cachep->num; if (num_objs - active_objs != cachep->lists.free_objects && !error) error = "free_objects accounting error"; name = cachep->name; if (error) printk(KERN_ERR "slab: cache %s error: %s\n", name, error); seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d", name, active_objs, num_objs, cachep->objsize, cachep->num, (1<<cachep->gfporder)); seq_printf(m, " : tunables %4u %4u %4u", cachep->limit, cachep->batchcount, cachep->lists.shared->limit/cachep->batchcount); seq_printf(m, " : slabdata %6lu %6lu %6u", active_slabs, num_slabs, cachep->lists.shared->avail); #if STATS { /* list3 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 free_limit = cachep->free_limit; unsigned long node_allocs = cachep->node_allocs; seq_printf(m, " : globalstat %7lu %6lu %5lu %4lu %4lu %4lu %4lu %4lu", allocs, high, grown, reaped, errors, max_freeable, free_limit, node_allocs); } /* 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 seq_putc(m, '\n'); spin_unlock_irq(&cachep->spinlock); return 0; } /* * slabinfo_op - iterator that generates /proc/slabinfo * * Output layout: * cache-name * num-active-objs * total-objs * object size * num-active-slabs * total-slabs * num-pages-per-slab * + further values on SMP and with statistics enabled */ struct seq_operations slabinfo_op = { .start = s_start, .next = s_next, .stop = s_stop, .show = s_show, }; #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 list_head *p; 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. */ down(&cache_chain_sem); res = -EINVAL; list_for_each(p,&cache_chain) { kmem_cache_t *cachep = list_entry(p, kmem_cache_t, next); if (!strcmp(cachep->name, kbuf)) { if (limit < 1 || batchcount < 1 || batchcount > limit || shared < 0) { res = -EINVAL; } else { res = do_tune_cpucache(cachep, limit, batchcount, shared); } break; } } up(&cache_chain_sem); if (res >= 0) res = count; return res; } #endif unsigned int ksize(const void *objp) { kmem_cache_t *c; unsigned long flags; unsigned int size = 0; if (likely(objp != NULL)) { local_irq_save(flags); c = GET_PAGE_CACHE(virt_to_page(objp)); size = kmem_cache_size(c); local_irq_restore(flags); } return size; } /* * kstrdup - allocate space for and copy an existing string * * @s: the string to duplicate * @gfp: the GFP mask used in the kmalloc() call when allocating memory */ char *kstrdup(const char *s, unsigned int __nocast gfp) { size_t len; char *buf; if (!s) return NULL; len = strlen(s) + 1; buf = kmalloc(len, gfp); if (buf) memcpy(buf, s, len); return buf; } EXPORT_SYMBOL(kstrdup);