/*
* 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 <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, int 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, int 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_kernel();
/* 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 long 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;
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, int 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);
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);
/* 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;
}
