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kernel-fxtec-pro1x/mm/slub.c
Roman Zippel f8bd2258e2 remove div_long_long_rem 
x86 is the only arch right now, which provides an optimized for
div_long_long_rem and it has the downside that one has to be very careful that
the divide doesn't overflow.

The API is a little akward, as the arguments for the unsigned divide are
signed.  The signed version also doesn't handle a negative divisor and
produces worse code on 64bit archs.

There is little incentive to keep this API alive, so this converts the few
users to the new API.

Signed-off-by: Roman Zippel <zippel@linux-m68k.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-05-01 08:03:58 -07:00

4509 lines
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/*
* SLUB: A slab allocator that limits cache line use instead of queuing
* objects in per cpu and per node lists.
*
* The allocator synchronizes using per slab locks and only
* uses a centralized lock to manage a pool of partial slabs.
*
* (C) 2007 SGI, Christoph Lameter <clameter@sgi.com>
*/
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/bit_spinlock.h>
#include <linux/interrupt.h>
#include <linux/bitops.h>
#include <linux/slab.h>
#include <linux/seq_file.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/mempolicy.h>
#include <linux/ctype.h>
#include <linux/debugobjects.h>
#include <linux/kallsyms.h>
#include <linux/memory.h>
#include <linux/math64.h>
/*
* Lock order:
* 1. slab_lock(page)
* 2. slab->list_lock
*
* The slab_lock protects operations on the object of a particular
* slab and its metadata in the page struct. If the slab lock
* has been taken then no allocations nor frees can be performed
* on the objects in the slab nor can the slab be added or removed
* from the partial or full lists since this would mean modifying
* the page_struct of the slab.
*
* The list_lock protects the partial and full list on each node and
* the partial slab counter. If taken then no new slabs may be added or
* removed from the lists nor make the number of partial slabs be modified.
* (Note that the total number of slabs is an atomic value that may be
* modified without taking the list lock).
*
* The list_lock is a centralized lock and thus we avoid taking it as
* much as possible. As long as SLUB does not have to handle partial
* slabs, operations can continue without any centralized lock. F.e.
* allocating a long series of objects that fill up slabs does not require
* the list lock.
*
* The lock order is sometimes inverted when we are trying to get a slab
* off a list. We take the list_lock and then look for a page on the list
* to use. While we do that objects in the slabs may be freed. We can
* only operate on the slab if we have also taken the slab_lock. So we use
* a slab_trylock() on the slab. If trylock was successful then no frees
* can occur anymore and we can use the slab for allocations etc. If the
* slab_trylock() does not succeed then frees are in progress in the slab and
* we must stay away from it for a while since we may cause a bouncing
* cacheline if we try to acquire the lock. So go onto the next slab.
* If all pages are busy then we may allocate a new slab instead of reusing
* a partial slab. A new slab has noone operating on it and thus there is
* no danger of cacheline contention.
*
* Interrupts are disabled during allocation and deallocation in order to
* make the slab allocator safe to use in the context of an irq. In addition
* interrupts are disabled to ensure that the processor does not change
* while handling per_cpu slabs, due to kernel preemption.
*
* SLUB assigns one slab for allocation to each processor.
* Allocations only occur from these slabs called cpu slabs.
*
* Slabs with free elements are kept on a partial list and during regular
* operations no list for full slabs is used. If an object in a full slab is
* freed then the slab will show up again on the partial lists.
* We track full slabs for debugging purposes though because otherwise we
* cannot scan all objects.
*
* Slabs are freed when they become empty. Teardown and setup is
* minimal so we rely on the page allocators per cpu caches for
* fast frees and allocs.
*
* Overloading of page flags that are otherwise used for LRU management.
*
* PageActive The slab is frozen and exempt from list processing.
* This means that the slab is dedicated to a purpose
* such as satisfying allocations for a specific
* processor. Objects may be freed in the slab while
* it is frozen but slab_free will then skip the usual
* list operations. It is up to the processor holding
* the slab to integrate the slab into the slab lists
* when the slab is no longer needed.
*
* One use of this flag is to mark slabs that are
* used for allocations. Then such a slab becomes a cpu
* slab. The cpu slab may be equipped with an additional
* freelist that allows lockless access to
* free objects in addition to the regular freelist
* that requires the slab lock.
*
* PageError Slab requires special handling due to debug
* options set. This moves slab handling out of
* the fast path and disables lockless freelists.
*/
#define FROZEN (1 << PG_active)
#ifdef CONFIG_SLUB_DEBUG
#define SLABDEBUG (1 << PG_error)
#else
#define SLABDEBUG 0
#endif
static inline int SlabFrozen(struct page *page)
{
return page->flags & FROZEN;
}
static inline void SetSlabFrozen(struct page *page)
{
page->flags |= FROZEN;
}
static inline void ClearSlabFrozen(struct page *page)
{
page->flags &= ~FROZEN;
}
static inline int SlabDebug(struct page *page)
{
return page->flags & SLABDEBUG;
}
static inline void SetSlabDebug(struct page *page)
{
page->flags |= SLABDEBUG;
}
static inline void ClearSlabDebug(struct page *page)
{
page->flags &= ~SLABDEBUG;
}
/*
* Issues still to be resolved:
*
* - Support PAGE_ALLOC_DEBUG. Should be easy to do.
*
* - Variable sizing of the per node arrays
*/
/* Enable to test recovery from slab corruption on boot */
#undef SLUB_RESILIENCY_TEST
/*
* Mininum number of partial slabs. These will be left on the partial
* lists even if they are empty. kmem_cache_shrink may reclaim them.
*/
#define MIN_PARTIAL 5
/*
* Maximum number of desirable partial slabs.
* The existence of more partial slabs makes kmem_cache_shrink
* sort the partial list by the number of objects in the.
*/
#define MAX_PARTIAL 10
#define DEBUG_DEFAULT_FLAGS (SLAB_DEBUG_FREE | SLAB_RED_ZONE | \
SLAB_POISON | SLAB_STORE_USER)
/*
* Set of flags that will prevent slab merging
*/
#define SLUB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
SLAB_TRACE | SLAB_DESTROY_BY_RCU)
#define SLUB_MERGE_SAME (SLAB_DEBUG_FREE | SLAB_RECLAIM_ACCOUNT | \
SLAB_CACHE_DMA)
#ifndef ARCH_KMALLOC_MINALIGN
#define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
#endif
#ifndef ARCH_SLAB_MINALIGN
#define ARCH_SLAB_MINALIGN __alignof__(unsigned long long)
#endif
/* Internal SLUB flags */
#define __OBJECT_POISON 0x80000000 /* Poison object */
#define __SYSFS_ADD_DEFERRED 0x40000000 /* Not yet visible via sysfs */
static int kmem_size = sizeof(struct kmem_cache);
#ifdef CONFIG_SMP
static struct notifier_block slab_notifier;
#endif
static enum {
DOWN, /* No slab functionality available */
PARTIAL, /* kmem_cache_open() works but kmalloc does not */
UP, /* Everything works but does not show up in sysfs */
SYSFS /* Sysfs up */
} slab_state = DOWN;
/* A list of all slab caches on the system */
static DECLARE_RWSEM(slub_lock);
static LIST_HEAD(slab_caches);
/*
* Tracking user of a slab.
*/
struct track {
void *addr; /* Called from address */
int cpu; /* Was running on cpu */
int pid; /* Pid context */
unsigned long when; /* When did the operation occur */
};
enum track_item { TRACK_ALLOC, TRACK_FREE };
#if defined(CONFIG_SYSFS) && defined(CONFIG_SLUB_DEBUG)
static int sysfs_slab_add(struct kmem_cache *);
static int sysfs_slab_alias(struct kmem_cache *, const char *);
static void sysfs_slab_remove(struct kmem_cache *);
#else
static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; }
static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p)
{ return 0; }
static inline void sysfs_slab_remove(struct kmem_cache *s)
{
kfree(s);
}
#endif
static inline void stat(struct kmem_cache_cpu *c, enum stat_item si)
{
#ifdef CONFIG_SLUB_STATS
c->stat[si]++;
#endif
}
/********************************************************************
* Core slab cache functions
*******************************************************************/
int slab_is_available(void)
{
return slab_state >= UP;
}
static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node)
{
#ifdef CONFIG_NUMA
return s->node[node];
#else
return &s->local_node;
#endif
}
static inline struct kmem_cache_cpu *get_cpu_slab(struct kmem_cache *s, int cpu)
{
#ifdef CONFIG_SMP
return s->cpu_slab[cpu];
#else
return &s->cpu_slab;
#endif
}
/* Verify that a pointer has an address that is valid within a slab page */
static inline int check_valid_pointer(struct kmem_cache *s,
struct page *page, const void *object)
{
void *base;
if (!object)
return 1;
base = page_address(page);
if (object < base || object >= base + page->objects * s->size ||
(object - base) % s->size) {
return 0;
}
return 1;
}
/*
* Slow version of get and set free pointer.
*
* This version requires touching the cache lines of kmem_cache which
* we avoid to do in the fast alloc free paths. There we obtain the offset
* from the page struct.
*/
static inline void *get_freepointer(struct kmem_cache *s, void *object)
{
return *(void **)(object + s->offset);
}
static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp)
{
*(void **)(object + s->offset) = fp;
}
/* Loop over all objects in a slab */
#define for_each_object(__p, __s, __addr, __objects) \
for (__p = (__addr); __p < (__addr) + (__objects) * (__s)->size;\
__p += (__s)->size)
/* Scan freelist */
#define for_each_free_object(__p, __s, __free) \
for (__p = (__free); __p; __p = get_freepointer((__s), __p))
/* Determine object index from a given position */
static inline int slab_index(void *p, struct kmem_cache *s, void *addr)
{
return (p - addr) / s->size;
}
static inline struct kmem_cache_order_objects oo_make(int order,
unsigned long size)
{
struct kmem_cache_order_objects x = {
(order << 16) + (PAGE_SIZE << order) / size
};
return x;
}
static inline int oo_order(struct kmem_cache_order_objects x)
{
return x.x >> 16;
}
static inline int oo_objects(struct kmem_cache_order_objects x)
{
return x.x & ((1 << 16) - 1);
}
#ifdef CONFIG_SLUB_DEBUG
/*
* Debug settings:
*/
#ifdef CONFIG_SLUB_DEBUG_ON
static int slub_debug = DEBUG_DEFAULT_FLAGS;
#else
static int slub_debug;
#endif
static char *slub_debug_slabs;
/*
* Object debugging
*/
static void print_section(char *text, u8 *addr, unsigned int length)
{
int i, offset;
int newline = 1;
char ascii[17];
ascii[16] = 0;
for (i = 0; i < length; i++) {
if (newline) {
printk(KERN_ERR "%8s 0x%p: ", text, addr + i);
newline = 0;
}
printk(KERN_CONT " %02x", addr[i]);
offset = i % 16;
ascii[offset] = isgraph(addr[i]) ? addr[i] : '.';
if (offset == 15) {
printk(KERN_CONT " %s\n", ascii);
newline = 1;
}
}
if (!newline) {
i %= 16;
while (i < 16) {
printk(KERN_CONT " ");
ascii[i] = ' ';
i++;
}
printk(KERN_CONT " %s\n", ascii);
}
}
static struct track *get_track(struct kmem_cache *s, void *object,
enum track_item alloc)
{
struct track *p;
if (s->offset)
p = object + s->offset + sizeof(void *);
else
p = object + s->inuse;
return p + alloc;
}
static void set_track(struct kmem_cache *s, void *object,
enum track_item alloc, void *addr)
{
struct track *p;
if (s->offset)
p = object + s->offset + sizeof(void *);
else
p = object + s->inuse;
p += alloc;
if (addr) {
p->addr = addr;
p->cpu = smp_processor_id();
p->pid = current ? current->pid : -1;
p->when = jiffies;
} else
memset(p, 0, sizeof(struct track));
}
static void init_tracking(struct kmem_cache *s, void *object)
{
if (!(s->flags & SLAB_STORE_USER))
return;
set_track(s, object, TRACK_FREE, NULL);
set_track(s, object, TRACK_ALLOC, NULL);
}
static void print_track(const char *s, struct track *t)
{
if (!t->addr)
return;
printk(KERN_ERR "INFO: %s in ", s);
__print_symbol("%s", (unsigned long)t->addr);
printk(" age=%lu cpu=%u pid=%d\n", jiffies - t->when, t->cpu, t->pid);
}
static void print_tracking(struct kmem_cache *s, void *object)
{
if (!(s->flags & SLAB_STORE_USER))
return;
print_track("Allocated", get_track(s, object, TRACK_ALLOC));
print_track("Freed", get_track(s, object, TRACK_FREE));
}
static void print_page_info(struct page *page)
{
printk(KERN_ERR "INFO: Slab 0x%p objects=%u used=%u fp=0x%p flags=0x%04lx\n",
page, page->objects, page->inuse, page->freelist, page->flags);
}
static void slab_bug(struct kmem_cache *s, char *fmt, ...)
{
va_list args;
char buf[100];
va_start(args, fmt);
vsnprintf(buf, sizeof(buf), fmt, args);
va_end(args);
printk(KERN_ERR "========================================"
"=====================================\n");
printk(KERN_ERR "BUG %s: %s\n", s->name, buf);
printk(KERN_ERR "----------------------------------------"
"-------------------------------------\n\n");
}
static void slab_fix(struct kmem_cache *s, char *fmt, ...)
{
va_list args;
char buf[100];
va_start(args, fmt);
vsnprintf(buf, sizeof(buf), fmt, args);
va_end(args);
printk(KERN_ERR "FIX %s: %s\n", s->name, buf);
}
static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
{
unsigned int off; /* Offset of last byte */
u8 *addr = page_address(page);
print_tracking(s, p);
print_page_info(page);
printk(KERN_ERR "INFO: Object 0x%p @offset=%tu fp=0x%p\n\n",
p, p - addr, get_freepointer(s, p));
if (p > addr + 16)
print_section("Bytes b4", p - 16, 16);
print_section("Object", p, min(s->objsize, 128));
if (s->flags & SLAB_RED_ZONE)
print_section("Redzone", p + s->objsize,
s->inuse - s->objsize);
if (s->offset)
off = s->offset + sizeof(void *);
else
off = s->inuse;
if (s->flags & SLAB_STORE_USER)
off += 2 * sizeof(struct track);
if (off != s->size)
/* Beginning of the filler is the free pointer */
print_section("Padding", p + off, s->size - off);
dump_stack();
}
static void object_err(struct kmem_cache *s, struct page *page,
u8 *object, char *reason)
{
slab_bug(s, "%s", reason);
print_trailer(s, page, object);
}
static void slab_err(struct kmem_cache *s, struct page *page, char *fmt, ...)
{
va_list args;
char buf[100];
va_start(args, fmt);
vsnprintf(buf, sizeof(buf), fmt, args);
va_end(args);
slab_bug(s, "%s", buf);
print_page_info(page);
dump_stack();
}
static void init_object(struct kmem_cache *s, void *object, int active)
{
u8 *p = object;
if (s->flags & __OBJECT_POISON) {
memset(p, POISON_FREE, s->objsize - 1);
p[s->objsize - 1] = POISON_END;
}
if (s->flags & SLAB_RED_ZONE)
memset(p + s->objsize,
active ? SLUB_RED_ACTIVE : SLUB_RED_INACTIVE,
s->inuse - s->objsize);
}
static u8 *check_bytes(u8 *start, unsigned int value, unsigned int bytes)
{
while (bytes) {
if (*start != (u8)value)
return start;
start++;
bytes--;
}
return NULL;
}
static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
void *from, void *to)
{
slab_fix(s, "Restoring 0x%p-0x%p=0x%x\n", from, to - 1, data);
memset(from, data, to - from);
}
static int check_bytes_and_report(struct kmem_cache *s, struct page *page,
u8 *object, char *what,
u8 *start, unsigned int value, unsigned int bytes)
{
u8 *fault;
u8 *end;
fault = check_bytes(start, value, bytes);
if (!fault)
return 1;
end = start + bytes;
while (end > fault && end[-1] == value)
end--;
slab_bug(s, "%s overwritten", what);
printk(KERN_ERR "INFO: 0x%p-0x%p. First byte 0x%x instead of 0x%x\n",
fault, end - 1, fault[0], value);
print_trailer(s, page, object);
restore_bytes(s, what, value, fault, end);
return 0;
}
/*
* Object layout:
*
* object address
* Bytes of the object to be managed.
* If the freepointer may overlay the object then the free
* pointer is the first word of the object.
*
* Poisoning uses 0x6b (POISON_FREE) and the last byte is
* 0xa5 (POISON_END)
*
* object + s->objsize
* Padding to reach word boundary. This is also used for Redzoning.
* Padding is extended by another word if Redzoning is enabled and
* objsize == inuse.
*
* We fill with 0xbb (RED_INACTIVE) for inactive objects and with
* 0xcc (RED_ACTIVE) for objects in use.
*
* object + s->inuse
* Meta data starts here.
*
* A. Free pointer (if we cannot overwrite object on free)
* B. Tracking data for SLAB_STORE_USER
* C. Padding to reach required alignment boundary or at mininum
* one word if debugging is on to be able to detect writes
* before the word boundary.
*
* Padding is done using 0x5a (POISON_INUSE)
*
* object + s->size
* Nothing is used beyond s->size.
*
* If slabcaches are merged then the objsize and inuse boundaries are mostly
* ignored. And therefore no slab options that rely on these boundaries
* may be used with merged slabcaches.
*/
static int check_pad_bytes(struct kmem_cache *s, struct page *page, u8 *p)
{
unsigned long off = s->inuse; /* The end of info */
if (s->offset)
/* Freepointer is placed after the object. */
off += sizeof(void *);
if (s->flags & SLAB_STORE_USER)
/* We also have user information there */
off += 2 * sizeof(struct track);
if (s->size == off)
return 1;
return check_bytes_and_report(s, page, p, "Object padding",
p + off, POISON_INUSE, s->size - off);
}
/* Check the pad bytes at the end of a slab page */
static int slab_pad_check(struct kmem_cache *s, struct page *page)
{
u8 *start;
u8 *fault;
u8 *end;
int length;
int remainder;
if (!(s->flags & SLAB_POISON))
return 1;
start = page_address(page);
length = (PAGE_SIZE << compound_order(page));
end = start + length;
remainder = length % s->size;
if (!remainder)
return 1;
fault = check_bytes(end - remainder, POISON_INUSE, remainder);
if (!fault)
return 1;
while (end > fault && end[-1] == POISON_INUSE)
end--;
slab_err(s, page, "Padding overwritten. 0x%p-0x%p", fault, end - 1);
print_section("Padding", end - remainder, remainder);
restore_bytes(s, "slab padding", POISON_INUSE, start, end);
return 0;
}
static int check_object(struct kmem_cache *s, struct page *page,
void *object, int active)
{
u8 *p = object;
u8 *endobject = object + s->objsize;
if (s->flags & SLAB_RED_ZONE) {
unsigned int red =
active ? SLUB_RED_ACTIVE : SLUB_RED_INACTIVE;
if (!check_bytes_and_report(s, page, object, "Redzone",
endobject, red, s->inuse - s->objsize))
return 0;
} else {
if ((s->flags & SLAB_POISON) && s->objsize < s->inuse) {
check_bytes_and_report(s, page, p, "Alignment padding",
endobject, POISON_INUSE, s->inuse - s->objsize);
}
}
if (s->flags & SLAB_POISON) {
if (!active && (s->flags & __OBJECT_POISON) &&
(!check_bytes_and_report(s, page, p, "Poison", p,
POISON_FREE, s->objsize - 1) ||
!check_bytes_and_report(s, page, p, "Poison",
p + s->objsize - 1, POISON_END, 1)))
return 0;
/*
* check_pad_bytes cleans up on its own.
*/
check_pad_bytes(s, page, p);
}
if (!s->offset && active)
/*
* Object and freepointer overlap. Cannot check
* freepointer while object is allocated.
*/
return 1;
/* Check free pointer validity */
if (!check_valid_pointer(s, page, get_freepointer(s, p))) {
object_err(s, page, p, "Freepointer corrupt");
/*
* No choice but to zap it and thus loose the remainder
* of the free objects in this slab. May cause
* another error because the object count is now wrong.
*/
set_freepointer(s, p, NULL);
return 0;
}
return 1;
}
static int check_slab(struct kmem_cache *s, struct page *page)
{
int maxobj;
VM_BUG_ON(!irqs_disabled());
if (!PageSlab(page)) {
slab_err(s, page, "Not a valid slab page");
return 0;
}
maxobj = (PAGE_SIZE << compound_order(page)) / s->size;
if (page->objects > maxobj) {
slab_err(s, page, "objects %u > max %u",
s->name, page->objects, maxobj);
return 0;
}
if (page->inuse > page->objects) {
slab_err(s, page, "inuse %u > max %u",
s->name, page->inuse, page->objects);
return 0;
}
/* Slab_pad_check fixes things up after itself */
slab_pad_check(s, page);
return 1;
}
/*
* Determine if a certain object on a page is on the freelist. Must hold the
* slab lock to guarantee that the chains are in a consistent state.
*/
static int on_freelist(struct kmem_cache *s, struct page *page, void *search)
{
int nr = 0;
void *fp = page->freelist;
void *object = NULL;
unsigned long max_objects;
while (fp && nr <= page->objects) {
if (fp == search)
return 1;
if (!check_valid_pointer(s, page, fp)) {
if (object) {
object_err(s, page, object,
"Freechain corrupt");
set_freepointer(s, object, NULL);
break;
} else {
slab_err(s, page, "Freepointer corrupt");
page->freelist = NULL;
page->inuse = page->objects;
slab_fix(s, "Freelist cleared");
return 0;
}
break;
}
object = fp;
fp = get_freepointer(s, object);
nr++;
}
max_objects = (PAGE_SIZE << compound_order(page)) / s->size;
if (max_objects > 65535)
max_objects = 65535;
if (page->objects != max_objects) {
slab_err(s, page, "Wrong number of objects. Found %d but "
"should be %d", page->objects, max_objects);
page->objects = max_objects;
slab_fix(s, "Number of objects adjusted.");
}
if (page->inuse != page->objects - nr) {
slab_err(s, page, "Wrong object count. Counter is %d but "
"counted were %d", page->inuse, page->objects - nr);
page->inuse = page->objects - nr;
slab_fix(s, "Object count adjusted.");
}
return search == NULL;
}
static void trace(struct kmem_cache *s, struct page *page, void *object, int alloc)
{
if (s->flags & SLAB_TRACE) {
printk(KERN_INFO "TRACE %s %s 0x%p inuse=%d fp=0x%p\n",
s->name,
alloc ? "alloc" : "free",
object, page->inuse,
page->freelist);
if (!alloc)
print_section("Object", (void *)object, s->objsize);
dump_stack();
}
}
/*
* Tracking of fully allocated slabs for debugging purposes.
*/
static void add_full(struct kmem_cache_node *n, struct page *page)
{
spin_lock(&n->list_lock);
list_add(&page->lru, &n->full);
spin_unlock(&n->list_lock);
}
static void remove_full(struct kmem_cache *s, struct page *page)
{
struct kmem_cache_node *n;
if (!(s->flags & SLAB_STORE_USER))
return;
n = get_node(s, page_to_nid(page));
spin_lock(&n->list_lock);
list_del(&page->lru);
spin_unlock(&n->list_lock);
}
/* Tracking of the number of slabs for debugging purposes */
static inline unsigned long slabs_node(struct kmem_cache *s, int node)
{
struct kmem_cache_node *n = get_node(s, node);
return atomic_long_read(&n->nr_slabs);
}
static inline void inc_slabs_node(struct kmem_cache *s, int node, int objects)
{
struct kmem_cache_node *n = get_node(s, node);
/*
* May be called early in order to allocate a slab for the
* kmem_cache_node structure. Solve the chicken-egg
* dilemma by deferring the increment of the count during
* bootstrap (see early_kmem_cache_node_alloc).
*/
if (!NUMA_BUILD || n) {
atomic_long_inc(&n->nr_slabs);
atomic_long_add(objects, &n->total_objects);
}
}
static inline void dec_slabs_node(struct kmem_cache *s, int node, int objects)
{
struct kmem_cache_node *n = get_node(s, node);
atomic_long_dec(&n->nr_slabs);
atomic_long_sub(objects, &n->total_objects);
}
/* Object debug checks for alloc/free paths */
static void setup_object_debug(struct kmem_cache *s, struct page *page,
void *object)
{
if (!(s->flags & (SLAB_STORE_USER|SLAB_RED_ZONE|__OBJECT_POISON)))
return;
init_object(s, object, 0);
init_tracking(s, object);
}
static int alloc_debug_processing(struct kmem_cache *s, struct page *page,
void *object, void *addr)
{
if (!check_slab(s, page))
goto bad;
if (!on_freelist(s, page, object)) {
object_err(s, page, object, "Object already allocated");
goto bad;
}
if (!check_valid_pointer(s, page, object)) {
object_err(s, page, object, "Freelist Pointer check fails");
goto bad;
}
if (!check_object(s, page, object, 0))
goto bad;
/* Success perform special debug activities for allocs */
if (s->flags & SLAB_STORE_USER)
set_track(s, object, TRACK_ALLOC, addr);
trace(s, page, object, 1);
init_object(s, object, 1);
return 1;
bad:
if (PageSlab(page)) {
/*
* If this is a slab page then lets do the best we can
* to avoid issues in the future. Marking all objects
* as used avoids touching the remaining objects.
*/
slab_fix(s, "Marking all objects used");
page->inuse = page->objects;
page->freelist = NULL;
}
return 0;
}
static int free_debug_processing(struct kmem_cache *s, struct page *page,
void *object, void *addr)
{
if (!check_slab(s, page))
goto fail;
if (!check_valid_pointer(s, page, object)) {
slab_err(s, page, "Invalid object pointer 0x%p", object);
goto fail;
}
if (on_freelist(s, page, object)) {
object_err(s, page, object, "Object already free");
goto fail;
}
if (!check_object(s, page, object, 1))
return 0;
if (unlikely(s != page->slab)) {
if (!PageSlab(page)) {
slab_err(s, page, "Attempt to free object(0x%p) "
"outside of slab", object);
} else if (!page->slab) {
printk(KERN_ERR
"SLUB <none>: no slab for object 0x%p.\n",
object);
dump_stack();
} else
object_err(s, page, object,
"page slab pointer corrupt.");
goto fail;
}
/* Special debug activities for freeing objects */
if (!SlabFrozen(page) && !page->freelist)
remove_full(s, page);
if (s->flags & SLAB_STORE_USER)
set_track(s, object, TRACK_FREE, addr);
trace(s, page, object, 0);
init_object(s, object, 0);
return 1;
fail:
slab_fix(s, "Object at 0x%p not freed", object);
return 0;
}
static int __init setup_slub_debug(char *str)
{
slub_debug = DEBUG_DEFAULT_FLAGS;
if (*str++ != '=' || !*str)
/*
* No options specified. Switch on full debugging.
*/
goto out;
if (*str == ',')
/*
* No options but restriction on slabs. This means full
* debugging for slabs matching a pattern.
*/
goto check_slabs;
slub_debug = 0;
if (*str == '-')
/*
* Switch off all debugging measures.
*/
goto out;
/*
* Determine which debug features should be switched on
*/
for (; *str && *str != ','; str++) {
switch (tolower(*str)) {
case 'f':
slub_debug |= SLAB_DEBUG_FREE;
break;
case 'z':
slub_debug |= SLAB_RED_ZONE;
break;
case 'p':
slub_debug |= SLAB_POISON;
break;
case 'u':
slub_debug |= SLAB_STORE_USER;
break;
case 't':
slub_debug |= SLAB_TRACE;
break;
default:
printk(KERN_ERR "slub_debug option '%c' "
"unknown. skipped\n", *str);
}
}
check_slabs:
if (*str == ',')
slub_debug_slabs = str + 1;
out:
return 1;
}
__setup("slub_debug", setup_slub_debug);
static unsigned long kmem_cache_flags(unsigned long objsize,
unsigned long flags, const char *name,
void (*ctor)(struct kmem_cache *, void *))
{
/*
* Enable debugging if selected on the kernel commandline.
*/
if (slub_debug && (!slub_debug_slabs ||
strncmp(slub_debug_slabs, name, strlen(slub_debug_slabs)) == 0))
flags |= slub_debug;
return flags;
}
#else
static inline void setup_object_debug(struct kmem_cache *s,
struct page *page, void *object) {}
static inline int alloc_debug_processing(struct kmem_cache *s,
struct page *page, void *object, void *addr) { return 0; }
static inline int free_debug_processing(struct kmem_cache *s,
struct page *page, void *object, void *addr) { return 0; }
static inline int slab_pad_check(struct kmem_cache *s, struct page *page)
{ return 1; }
static inline int check_object(struct kmem_cache *s, struct page *page,
void *object, int active) { return 1; }
static inline void add_full(struct kmem_cache_node *n, struct page *page) {}
static inline unsigned long kmem_cache_flags(unsigned long objsize,
unsigned long flags, const char *name,
void (*ctor)(struct kmem_cache *, void *))
{
return flags;
}
#define slub_debug 0
static inline unsigned long slabs_node(struct kmem_cache *s, int node)
{ return 0; }
static inline void inc_slabs_node(struct kmem_cache *s, int node,
int objects) {}
static inline void dec_slabs_node(struct kmem_cache *s, int node,
int objects) {}
#endif
/*
* Slab allocation and freeing
*/
static inline struct page *alloc_slab_page(gfp_t flags, int node,
struct kmem_cache_order_objects oo)
{
int order = oo_order(oo);
if (node == -1)
return alloc_pages(flags, order);
else
return alloc_pages_node(node, flags, order);
}
static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
{
struct page *page;
struct kmem_cache_order_objects oo = s->oo;
flags |= s->allocflags;
page = alloc_slab_page(flags | __GFP_NOWARN | __GFP_NORETRY, node,
oo);
if (unlikely(!page)) {
oo = s->min;
/*
* Allocation may have failed due to fragmentation.
* Try a lower order alloc if possible
*/
page = alloc_slab_page(flags, node, oo);
if (!page)
return NULL;
stat(get_cpu_slab(s, raw_smp_processor_id()), ORDER_FALLBACK);
}
page->objects = oo_objects(oo);
mod_zone_page_state(page_zone(page),
(s->flags & SLAB_RECLAIM_ACCOUNT) ?
NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
1 << oo_order(oo));
return page;
}
static void setup_object(struct kmem_cache *s, struct page *page,
void *object)
{
setup_object_debug(s, page, object);
if (unlikely(s->ctor))
s->ctor(s, object);
}
static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
{
struct page *page;
void *start;
void *last;
void *p;
BUG_ON(flags & GFP_SLAB_BUG_MASK);
page = allocate_slab(s,
flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
if (!page)
goto out;
inc_slabs_node(s, page_to_nid(page), page->objects);
page->slab = s;
page->flags |= 1 << PG_slab;
if (s->flags & (SLAB_DEBUG_FREE | SLAB_RED_ZONE | SLAB_POISON |
SLAB_STORE_USER | SLAB_TRACE))
SetSlabDebug(page);
start = page_address(page);
if (unlikely(s->flags & SLAB_POISON))
memset(start, POISON_INUSE, PAGE_SIZE << compound_order(page));
last = start;
for_each_object(p, s, start, page->objects) {
setup_object(s, page, last);
set_freepointer(s, last, p);
last = p;
}
setup_object(s, page, last);
set_freepointer(s, last, NULL);
page->freelist = start;
page->inuse = 0;
out:
return page;
}
static void __free_slab(struct kmem_cache *s, struct page *page)
{
int order = compound_order(page);
int pages = 1 << order;
if (unlikely(SlabDebug(page))) {
void *p;
slab_pad_check(s, page);
for_each_object(p, s, page_address(page),
page->objects)
check_object(s, page, p, 0);
ClearSlabDebug(page);
}
mod_zone_page_state(page_zone(page),
(s->flags & SLAB_RECLAIM_ACCOUNT) ?
NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
-pages);
__ClearPageSlab(page);
reset_page_mapcount(page);
__free_pages(page, order);
}
static void rcu_free_slab(struct rcu_head *h)
{
struct page *page;
page = container_of((struct list_head *)h, struct page, lru);
__free_slab(page->slab, page);
}
static void free_slab(struct kmem_cache *s, struct page *page)
{
if (unlikely(s->flags & SLAB_DESTROY_BY_RCU)) {
/*
* RCU free overloads the RCU head over the LRU
*/
struct rcu_head *head = (void *)&page->lru;
call_rcu(head, rcu_free_slab);
} else
__free_slab(s, page);
}
static void discard_slab(struct kmem_cache *s, struct page *page)
{
dec_slabs_node(s, page_to_nid(page), page->objects);
free_slab(s, page);
}
/*
* Per slab locking using the pagelock
*/
static __always_inline void slab_lock(struct page *page)
{
bit_spin_lock(PG_locked, &page->flags);
}
static __always_inline void slab_unlock(struct page *page)
{
__bit_spin_unlock(PG_locked, &page->flags);
}
static __always_inline int slab_trylock(struct page *page)
{
int rc = 1;
rc = bit_spin_trylock(PG_locked, &page->flags);
return rc;
}
/*
* Management of partially allocated slabs
*/
static void add_partial(struct kmem_cache_node *n,
struct page *page, int tail)
{
spin_lock(&n->list_lock);
n->nr_partial++;
if (tail)
list_add_tail(&page->lru, &n->partial);
else
list_add(&page->lru, &n->partial);
spin_unlock(&n->list_lock);
}
static void remove_partial(struct kmem_cache *s,
struct page *page)
{
struct kmem_cache_node *n = get_node(s, page_to_nid(page));
spin_lock(&n->list_lock);
list_del(&page->lru);
n->nr_partial--;
spin_unlock(&n->list_lock);
}
/*
* Lock slab and remove from the partial list.
*
* Must hold list_lock.
*/
static inline int lock_and_freeze_slab(struct kmem_cache_node *n, struct page *page)
{
if (slab_trylock(page)) {
list_del(&page->lru);
n->nr_partial--;
SetSlabFrozen(page);
return 1;
}
return 0;
}
/*
* Try to allocate a partial slab from a specific node.
*/
static struct page *get_partial_node(struct kmem_cache_node *n)
{
struct page *page;
/*
* Racy check. If we mistakenly see no partial slabs then we
* just allocate an empty slab. If we mistakenly try to get a
* partial slab and there is none available then get_partials()
* will return NULL.
*/
if (!n || !n->nr_partial)
return NULL;
spin_lock(&n->list_lock);
list_for_each_entry(page, &n->partial, lru)
if (lock_and_freeze_slab(n, page))
goto out;
page = NULL;
out:
spin_unlock(&n->list_lock);
return page;
}
/*
* Get a page from somewhere. Search in increasing NUMA distances.
*/
static struct page *get_any_partial(struct kmem_cache *s, gfp_t flags)
{
#ifdef CONFIG_NUMA
struct zonelist *zonelist;
struct zoneref *z;
struct zone *zone;
enum zone_type high_zoneidx = gfp_zone(flags);
struct page *page;
/*
* The defrag ratio allows a configuration of the tradeoffs between
* inter node defragmentation and node local allocations. A lower
* defrag_ratio increases the tendency to do local allocations
* instead of attempting to obtain partial slabs from other nodes.
*
* If the defrag_ratio is set to 0 then kmalloc() always
* returns node local objects. If the ratio is higher then kmalloc()
* may return off node objects because partial slabs are obtained
* from other nodes and filled up.
*
* If /sys/kernel/slab/xx/defrag_ratio is set to 100 (which makes
* defrag_ratio = 1000) then every (well almost) allocation will
* first attempt to defrag slab caches on other nodes. This means
* scanning over all nodes to look for partial slabs which may be
* expensive if we do it every time we are trying to find a slab
* with available objects.
*/
if (!s->remote_node_defrag_ratio ||
get_cycles() % 1024 > s->remote_node_defrag_ratio)
return NULL;
zonelist = node_zonelist(slab_node(current->mempolicy), flags);
for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
struct kmem_cache_node *n;
n = get_node(s, zone_to_nid(zone));
if (n && cpuset_zone_allowed_hardwall(zone, flags) &&
n->nr_partial > MIN_PARTIAL) {
page = get_partial_node(n);
if (page)
return page;
}
}
#endif
return NULL;
}
/*
* Get a partial page, lock it and return it.
*/
static struct page *get_partial(struct kmem_cache *s, gfp_t flags, int node)
{
struct page *page;
int searchnode = (node == -1) ? numa_node_id() : node;
page = get_partial_node(get_node(s, searchnode));
if (page || (flags & __GFP_THISNODE))
return page;
return get_any_partial(s, flags);
}
/*
* Move a page back to the lists.
*
* Must be called with the slab lock held.
*
* On exit the slab lock will have been dropped.
*/
static void unfreeze_slab(struct kmem_cache *s, struct page *page, int tail)
{
struct kmem_cache_node *n = get_node(s, page_to_nid(page));
struct kmem_cache_cpu *c = get_cpu_slab(s, smp_processor_id());
ClearSlabFrozen(page);
if (page->inuse) {
if (page->freelist) {
add_partial(n, page, tail);
stat(c, tail ? DEACTIVATE_TO_TAIL : DEACTIVATE_TO_HEAD);
} else {
stat(c, DEACTIVATE_FULL);
if (SlabDebug(page) && (s->flags & SLAB_STORE_USER))
add_full(n, page);
}
slab_unlock(page);
} else {
stat(c, DEACTIVATE_EMPTY);
if (n->nr_partial < MIN_PARTIAL) {
/*
* Adding an empty slab to the partial slabs in order
* to avoid page allocator overhead. This slab needs
* to come after the other slabs with objects in
* so that the others get filled first. That way the
* size of the partial list stays small.
*
* kmem_cache_shrink can reclaim any empty slabs from the
* partial list.
*/
add_partial(n, page, 1);
slab_unlock(page);
} else {
slab_unlock(page);
stat(get_cpu_slab(s, raw_smp_processor_id()), FREE_SLAB);
discard_slab(s, page);
}
}
}
/*
* Remove the cpu slab
*/
static void deactivate_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
{
struct page *page = c->page;
int tail = 1;
if (page->freelist)
stat(c, DEACTIVATE_REMOTE_FREES);
/*
* Merge cpu freelist into slab freelist. Typically we get here
* because both freelists are empty. So this is unlikely
* to occur.
*/
while (unlikely(c->freelist)) {
void **object;
tail = 0; /* Hot objects. Put the slab first */
/* Retrieve object from cpu_freelist */
object = c->freelist;
c->freelist = c->freelist[c->offset];
/* And put onto the regular freelist */
object[c->offset] = page->freelist;
page->freelist = object;
page->inuse--;
}
c->page = NULL;
unfreeze_slab(s, page, tail);
}
static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
{
stat(c, CPUSLAB_FLUSH);
slab_lock(c->page);
deactivate_slab(s, c);
}
/*
* Flush cpu slab.
*
* Called from IPI handler with interrupts disabled.
*/
static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu)
{
struct kmem_cache_cpu *c = get_cpu_slab(s, cpu);
if (likely(c && c->page))
flush_slab(s, c);
}
static void flush_cpu_slab(void *d)
{
struct kmem_cache *s = d;
__flush_cpu_slab(s, smp_processor_id());
}
static void flush_all(struct kmem_cache *s)
{
#ifdef CONFIG_SMP
on_each_cpu(flush_cpu_slab, s, 1, 1);
#else
unsigned long flags;
local_irq_save(flags);
flush_cpu_slab(s);
local_irq_restore(flags);
#endif
}
/*
* Check if the objects in a per cpu structure fit numa
* locality expectations.
*/
static inline int node_match(struct kmem_cache_cpu *c, int node)
{
#ifdef CONFIG_NUMA
if (node != -1 && c->node != node)
return 0;
#endif
return 1;
}
/*
* Slow path. The lockless freelist is empty or we need to perform
* debugging duties.
*
* Interrupts are disabled.
*
* Processing is still very fast if new objects have been freed to the
* regular freelist. In that case we simply take over the regular freelist
* as the lockless freelist and zap the regular freelist.
*
* If that is not working then we fall back to the partial lists. We take the
* first element of the freelist as the object to allocate now and move the
* rest of the freelist to the lockless freelist.
*
* And if we were unable to get a new slab from the partial slab lists then
* we need to allocate a new slab. This is the slowest path since it involves
* a call to the page allocator and the setup of a new slab.
*/
static void *__slab_alloc(struct kmem_cache *s,
gfp_t gfpflags, int node, void *addr, struct kmem_cache_cpu *c)
{
void **object;
struct page *new;
/* We handle __GFP_ZERO in the caller */
gfpflags &= ~__GFP_ZERO;
if (!c->page)
goto new_slab;
slab_lock(c->page);
if (unlikely(!node_match(c, node)))
goto another_slab;
stat(c, ALLOC_REFILL);
load_freelist:
object = c->page->freelist;
if (unlikely(!object))
goto another_slab;
if (unlikely(SlabDebug(c->page)))
goto debug;
c->freelist = object[c->offset];
c->page->inuse = c->page->objects;
c->page->freelist = NULL;
c->node = page_to_nid(c->page);
unlock_out:
slab_unlock(c->page);
stat(c, ALLOC_SLOWPATH);
return object;
another_slab:
deactivate_slab(s, c);
new_slab:
new = get_partial(s, gfpflags, node);
if (new) {
c->page = new;
stat(c, ALLOC_FROM_PARTIAL);
goto load_freelist;
}
if (gfpflags & __GFP_WAIT)
local_irq_enable();
new = new_slab(s, gfpflags, node);
if (gfpflags & __GFP_WAIT)
local_irq_disable();
if (new) {
c = get_cpu_slab(s, smp_processor_id());
stat(c, ALLOC_SLAB);
if (c->page)
flush_slab(s, c);
slab_lock(new);
SetSlabFrozen(new);
c->page = new;
goto load_freelist;
}
return NULL;
debug:
if (!alloc_debug_processing(s, c->page, object, addr))
goto another_slab;
c->page->inuse++;
c->page->freelist = object[c->offset];
c->node = -1;
goto unlock_out;
}
/*
* Inlined fastpath so that allocation functions (kmalloc, kmem_cache_alloc)
* have the fastpath folded into their functions. So no function call
* overhead for requests that can be satisfied on the fastpath.
*
* The fastpath works by first checking if the lockless freelist can be used.
* If not then __slab_alloc is called for slow processing.
*
* Otherwise we can simply pick the next object from the lockless free list.
*/
static __always_inline void *slab_alloc(struct kmem_cache *s,
gfp_t gfpflags, int node, void *addr)
{
void **object;
struct kmem_cache_cpu *c;
unsigned long flags;
local_irq_save(flags);
c = get_cpu_slab(s, smp_processor_id());
if (unlikely(!c->freelist || !node_match(c, node)))
object = __slab_alloc(s, gfpflags, node, addr, c);
else {
object = c->freelist;
c->freelist = object[c->offset];
stat(c, ALLOC_FASTPATH);
}
local_irq_restore(flags);
if (unlikely((gfpflags & __GFP_ZERO) && object))
memset(object, 0, c->objsize);
return object;
}
void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags)
{
return slab_alloc(s, gfpflags, -1, __builtin_return_address(0));
}
EXPORT_SYMBOL(kmem_cache_alloc);
#ifdef CONFIG_NUMA
void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node)
{
return slab_alloc(s, gfpflags, node, __builtin_return_address(0));
}
EXPORT_SYMBOL(kmem_cache_alloc_node);
#endif
/*
* Slow patch handling. This may still be called frequently since objects
* have a longer lifetime than the cpu slabs in most processing loads.
*
* So we still attempt to reduce cache line usage. Just take the slab
* lock and free the item. If there is no additional partial page
* handling required then we can return immediately.
*/
static void __slab_free(struct kmem_cache *s, struct page *page,
void *x, void *addr, unsigned int offset)
{
void *prior;
void **object = (void *)x;
struct kmem_cache_cpu *c;
c = get_cpu_slab(s, raw_smp_processor_id());
stat(c, FREE_SLOWPATH);
slab_lock(page);
if (unlikely(SlabDebug(page)))
goto debug;
checks_ok:
prior = object[offset] = page->freelist;
page->freelist = object;
page->inuse--;
if (unlikely(SlabFrozen(page))) {
stat(c, FREE_FROZEN);
goto out_unlock;
}
if (unlikely(!page->inuse))
goto slab_empty;
/*
* Objects left in the slab. If it was not on the partial list before
* then add it.
*/
if (unlikely(!prior)) {
add_partial(get_node(s, page_to_nid(page)), page, 1);
stat(c, FREE_ADD_PARTIAL);
}
out_unlock:
slab_unlock(page);
return;
slab_empty:
if (prior) {
/*
* Slab still on the partial list.
*/
remove_partial(s, page);
stat(c, FREE_REMOVE_PARTIAL);
}
slab_unlock(page);
stat(c, FREE_SLAB);
discard_slab(s, page);
return;
debug:
if (!free_debug_processing(s, page, x, addr))
goto out_unlock;
goto checks_ok;
}
/*
* Fastpath with forced inlining to produce a kfree and kmem_cache_free that
* can perform fastpath freeing without additional function calls.
*
* The fastpath is only possible if we are freeing to the current cpu slab
* of this processor. This typically the case if we have just allocated
* the item before.
*
* If fastpath is not possible then fall back to __slab_free where we deal
* with all sorts of special processing.
*/
static __always_inline void slab_free(struct kmem_cache *s,
struct page *page, void *x, void *addr)
{
void **object = (void *)x;
struct kmem_cache_cpu *c;
unsigned long flags;
local_irq_save(flags);
c = get_cpu_slab(s, smp_processor_id());
debug_check_no_locks_freed(object, c->objsize);
if (!(s->flags & SLAB_DEBUG_OBJECTS))
debug_check_no_obj_freed(object, s->objsize);
if (likely(page == c->page && c->node >= 0)) {
object[c->offset] = c->freelist;
c->freelist = object;
stat(c, FREE_FASTPATH);
} else
__slab_free(s, page, x, addr, c->offset);
local_irq_restore(flags);
}
void kmem_cache_free(struct kmem_cache *s, void *x)
{
struct page *page;
page = virt_to_head_page(x);
slab_free(s, page, x, __builtin_return_address(0));
}
EXPORT_SYMBOL(kmem_cache_free);
/* Figure out on which slab object the object resides */
static struct page *get_object_page(const void *x)
{
struct page *page = virt_to_head_page(x);
if (!PageSlab(page))
return NULL;
return page;
}
/*
* Object placement in a slab is made very easy because we always start at
* offset 0. If we tune the size of the object to the alignment then we can
* get the required alignment by putting one properly sized object after
* another.
*
* Notice that the allocation order determines the sizes of the per cpu
* caches. Each processor has always one slab available for allocations.
* Increasing the allocation order reduces the number of times that slabs
* must be moved on and off the partial lists and is therefore a factor in
* locking overhead.
*/
/*
* Mininum / Maximum order of slab pages. This influences locking overhead
* and slab fragmentation. A higher order reduces the number of partial slabs
* and increases the number of allocations possible without having to
* take the list_lock.
*/
static int slub_min_order;
static int slub_max_order = PAGE_ALLOC_COSTLY_ORDER;
static int slub_min_objects;
/*
* Merge control. If this is set then no merging of slab caches will occur.
* (Could be removed. This was introduced to pacify the merge skeptics.)
*/
static int slub_nomerge;
/*
* Calculate the order of allocation given an slab object size.
*
* The order of allocation has significant impact on performance and other
* system components. Generally order 0 allocations should be preferred since
* order 0 does not cause fragmentation in the page allocator. Larger objects
* be problematic to put into order 0 slabs because there may be too much
* unused space left. We go to a higher order if more than 1/16th of the slab
* would be wasted.
*
* In order to reach satisfactory performance we must ensure that a minimum
* number of objects is in one slab. Otherwise we may generate too much
* activity on the partial lists which requires taking the list_lock. This is
* less a concern for large slabs though which are rarely used.
*
* slub_max_order specifies the order where we begin to stop considering the
* number of objects in a slab as critical. If we reach slub_max_order then
* we try to keep the page order as low as possible. So we accept more waste
* of space in favor of a small page order.
*
* Higher order allocations also allow the placement of more objects in a
* slab and thereby reduce object handling overhead. If the user has
* requested a higher mininum order then we start with that one instead of
* the smallest order which will fit the object.
*/
static inline int slab_order(int size, int min_objects,
int max_order, int fract_leftover)
{
int order;
int rem;
int min_order = slub_min_order;
if ((PAGE_SIZE << min_order) / size > 65535)
return get_order(size * 65535) - 1;
for (order = max(min_order,
fls(min_objects * size - 1) - PAGE_SHIFT);
order <= max_order; order++) {
unsigned long slab_size = PAGE_SIZE << order;
if (slab_size < min_objects * size)
continue;
rem = slab_size % size;
if (rem <= slab_size / fract_leftover)
break;
}
return order;
}
static inline int calculate_order(int size)
{
int order;
int min_objects;
int fraction;
/*
* Attempt to find best configuration for a slab. This
* works by first attempting to generate a layout with
* the best configuration and backing off gradually.
*
* First we reduce the acceptable waste in a slab. Then
* we reduce the minimum objects required in a slab.
*/
min_objects = slub_min_objects;
if (!min_objects)
min_objects = 4 * (fls(nr_cpu_ids) + 1);
while (min_objects > 1) {
fraction = 16;
while (fraction >= 4) {
order = slab_order(size, min_objects,
slub_max_order, fraction);
if (order <= slub_max_order)
return order;
fraction /= 2;
}
min_objects /= 2;
}
/*
* We were unable to place multiple objects in a slab. Now
* lets see if we can place a single object there.
*/
order = slab_order(size, 1, slub_max_order, 1);
if (order <= slub_max_order)
return order;
/*
* Doh this slab cannot be placed using slub_max_order.
*/
order = slab_order(size, 1, MAX_ORDER, 1);
if (order <= MAX_ORDER)
return order;
return -ENOSYS;
}
/*
* Figure out what the alignment of the objects will be.
*/
static unsigned long calculate_alignment(unsigned long flags,
unsigned long align, unsigned long size)
{
/*
* If the user wants hardware cache aligned objects then follow that
* suggestion if the object is sufficiently large.
*
* The hardware cache alignment cannot override the specified
* alignment though. If that is greater then use it.
*/
if (flags & SLAB_HWCACHE_ALIGN) {
unsigned long ralign = cache_line_size();
while (size <= ralign / 2)
ralign /= 2;
align = max(align, ralign);
}
if (align < ARCH_SLAB_MINALIGN)
align = ARCH_SLAB_MINALIGN;
return ALIGN(align, sizeof(void *));
}
static void init_kmem_cache_cpu(struct kmem_cache *s,
struct kmem_cache_cpu *c)
{
c->page = NULL;
c->freelist = NULL;
c->node = 0;
c->offset = s->offset / sizeof(void *);
c->objsize = s->objsize;
#ifdef CONFIG_SLUB_STATS
memset(c->stat, 0, NR_SLUB_STAT_ITEMS * sizeof(unsigned));
#endif
}
static void init_kmem_cache_node(struct kmem_cache_node *n)
{
n->nr_partial = 0;
spin_lock_init(&n->list_lock);
INIT_LIST_HEAD(&n->partial);
#ifdef CONFIG_SLUB_DEBUG
atomic_long_set(&n->nr_slabs, 0);
INIT_LIST_HEAD(&n->full);
#endif
}
#ifdef CONFIG_SMP
/*
* Per cpu array for per cpu structures.
*
* The per cpu array places all kmem_cache_cpu structures from one processor
* close together meaning that it becomes possible that multiple per cpu
* structures are contained in one cacheline. This may be particularly
* beneficial for the kmalloc caches.
*
* A desktop system typically has around 60-80 slabs. With 100 here we are
* likely able to get per cpu structures for all caches from the array defined
* here. We must be able to cover all kmalloc caches during bootstrap.
*
* If the per cpu array is exhausted then fall back to kmalloc
* of individual cachelines. No sharing is possible then.
*/
#define NR_KMEM_CACHE_CPU 100
static DEFINE_PER_CPU(struct kmem_cache_cpu,
kmem_cache_cpu)[NR_KMEM_CACHE_CPU];
static DEFINE_PER_CPU(struct kmem_cache_cpu *, kmem_cache_cpu_free);
static cpumask_t kmem_cach_cpu_free_init_once = CPU_MASK_NONE;
static struct kmem_cache_cpu *alloc_kmem_cache_cpu(struct kmem_cache *s,
int cpu, gfp_t flags)
{
struct kmem_cache_cpu *c = per_cpu(kmem_cache_cpu_free, cpu);
if (c)
per_cpu(kmem_cache_cpu_free, cpu) =
(void *)c->freelist;
else {
/* Table overflow: So allocate ourselves */
c = kmalloc_node(
ALIGN(sizeof(struct kmem_cache_cpu), cache_line_size()),
flags, cpu_to_node(cpu));
if (!c)
return NULL;
}
init_kmem_cache_cpu(s, c);
return c;
}
static void free_kmem_cache_cpu(struct kmem_cache_cpu *c, int cpu)
{
if (c < per_cpu(kmem_cache_cpu, cpu) ||
c > per_cpu(kmem_cache_cpu, cpu) + NR_KMEM_CACHE_CPU) {
kfree(c);
return;
}
c->freelist = (void *)per_cpu(kmem_cache_cpu_free, cpu);
per_cpu(kmem_cache_cpu_free, cpu) = c;
}
static void free_kmem_cache_cpus(struct kmem_cache *s)
{
int cpu;
for_each_online_cpu(cpu) {
struct kmem_cache_cpu *c = get_cpu_slab(s, cpu);
if (c) {
s->cpu_slab[cpu] = NULL;
free_kmem_cache_cpu(c, cpu);
}
}
}
static int alloc_kmem_cache_cpus(struct kmem_cache *s, gfp_t flags)
{
int cpu;
for_each_online_cpu(cpu) {
struct kmem_cache_cpu *c = get_cpu_slab(s, cpu);
if (c)
continue;
c = alloc_kmem_cache_cpu(s, cpu, flags);
if (!c) {
free_kmem_cache_cpus(s);
return 0;
}
s->cpu_slab[cpu] = c;
}
return 1;
}
/*
* Initialize the per cpu array.
*/
static void init_alloc_cpu_cpu(int cpu)
{
int i;
if (cpu_isset(cpu, kmem_cach_cpu_free_init_once))
return;
for (i = NR_KMEM_CACHE_CPU - 1; i >= 0; i--)
free_kmem_cache_cpu(&per_cpu(kmem_cache_cpu, cpu)[i], cpu);
cpu_set(cpu, kmem_cach_cpu_free_init_once);
}
static void __init init_alloc_cpu(void)
{
int cpu;
for_each_online_cpu(cpu)
init_alloc_cpu_cpu(cpu);
}
#else
static inline void free_kmem_cache_cpus(struct kmem_cache *s) {}
static inline void init_alloc_cpu(void) {}
static inline int alloc_kmem_cache_cpus(struct kmem_cache *s, gfp_t flags)
{
init_kmem_cache_cpu(s, &s->cpu_slab);
return 1;
}
#endif
#ifdef CONFIG_NUMA
/*
* No kmalloc_node yet so do it by hand. We know that this is the first
* slab on the node for this slabcache. There are no concurrent accesses
* possible.
*
* Note that this function only works on the kmalloc_node_cache
* when allocating for the kmalloc_node_cache. This is used for bootstrapping
* memory on a fresh node that has no slab structures yet.
*/
static struct kmem_cache_node *early_kmem_cache_node_alloc(gfp_t gfpflags,
int node)
{
struct page *page;
struct kmem_cache_node *n;
unsigned long flags;
BUG_ON(kmalloc_caches->size < sizeof(struct kmem_cache_node));
page = new_slab(kmalloc_caches, gfpflags, node);
BUG_ON(!page);
if (page_to_nid(page) != node) {
printk(KERN_ERR "SLUB: Unable to allocate memory from "
"node %d\n", node);
printk(KERN_ERR "SLUB: Allocating a useless per node structure "
"in order to be able to continue\n");
}
n = page->freelist;
BUG_ON(!n);
page->freelist = get_freepointer(kmalloc_caches, n);
page->inuse++;
kmalloc_caches->node[node] = n;
#ifdef CONFIG_SLUB_DEBUG
init_object(kmalloc_caches, n, 1);
init_tracking(kmalloc_caches, n);
#endif
init_kmem_cache_node(n);
inc_slabs_node(kmalloc_caches, node, page->objects);
/*
* lockdep requires consistent irq usage for each lock
* so even though there cannot be a race this early in
* the boot sequence, we still disable irqs.
*/
local_irq_save(flags);
add_partial(n, page, 0);
local_irq_restore(flags);
return n;
}
static void free_kmem_cache_nodes(struct kmem_cache *s)
{
int node;
for_each_node_state(node, N_NORMAL_MEMORY) {
struct kmem_cache_node *n = s->node[node];
if (n && n != &s->local_node)
kmem_cache_free(kmalloc_caches, n);
s->node[node] = NULL;
}
}
static int init_kmem_cache_nodes(struct kmem_cache *s, gfp_t gfpflags)
{
int node;
int local_node;
if (slab_state >= UP)
local_node = page_to_nid(virt_to_page(s));
else
local_node = 0;
for_each_node_state(node, N_NORMAL_MEMORY) {
struct kmem_cache_node *n;
if (local_node == node)
n = &s->local_node;
else {
if (slab_state == DOWN) {
n = early_kmem_cache_node_alloc(gfpflags,
node);
continue;
}
n = kmem_cache_alloc_node(kmalloc_caches,
gfpflags, node);
if (!n) {
free_kmem_cache_nodes(s);
return 0;
}
}
s->node[node] = n;
init_kmem_cache_node(n);
}
return 1;
}
#else
static void free_kmem_cache_nodes(struct kmem_cache *s)
{
}
static int init_kmem_cache_nodes(struct kmem_cache *s, gfp_t gfpflags)
{
init_kmem_cache_node(&s->local_node);
return 1;
}
#endif
/*
* calculate_sizes() determines the order and the distribution of data within
* a slab object.
*/
static int calculate_sizes(struct kmem_cache *s, int forced_order)
{
unsigned long flags = s->flags;
unsigned long size = s->objsize;
unsigned long align = s->align;
int order;
/*
* Round up object size to the next word boundary. We can only
* place the free pointer at word boundaries and this determines
* the possible location of the free pointer.
*/
size = ALIGN(size, sizeof(void *));
#ifdef CONFIG_SLUB_DEBUG
/*
* Determine if we can poison the object itself. If the user of
* the slab may touch the object after free or before allocation
* then we should never poison the object itself.
*/
if ((flags & SLAB_POISON) && !(flags & SLAB_DESTROY_BY_RCU) &&
!s->ctor)
s->flags |= __OBJECT_POISON;
else
s->flags &= ~__OBJECT_POISON;
/*
* If we are Redzoning then check if there is some space between the
* end of the object and the free pointer. If not then add an
* additional word to have some bytes to store Redzone information.
*/
if ((flags & SLAB_RED_ZONE) && size == s->objsize)
size += sizeof(void *);
#endif
/*
* With that we have determined the number of bytes in actual use
* by the object. This is the potential offset to the free pointer.
*/
s->inuse = size;
if (((flags & (SLAB_DESTROY_BY_RCU | SLAB_POISON)) ||
s->ctor)) {
/*
* Relocate free pointer after the object if it is not
* permitted to overwrite the first word of the object on
* kmem_cache_free.
*
* This is the case if we do RCU, have a constructor or
* destructor or are poisoning the objects.
*/
s->offset = size;
size += sizeof(void *);
}
#ifdef CONFIG_SLUB_DEBUG
if (flags & SLAB_STORE_USER)
/*
* Need to store information about allocs and frees after
* the object.
*/
size += 2 * sizeof(struct track);
if (flags & SLAB_RED_ZONE)
/*
* Add some empty padding so that we can catch
* overwrites from earlier objects rather than let
* tracking information or the free pointer be
* corrupted if an user writes before the start
* of the object.
*/
size += sizeof(void *);
#endif
/*
* Determine the alignment based on various parameters that the
* user specified and the dynamic determination of cache line size
* on bootup.
*/
align = calculate_alignment(flags, align, s->objsize);
/*
* SLUB stores one object immediately after another beginning from
* offset 0. In order to align the objects we have to simply size
* each object to conform to the alignment.
*/
size = ALIGN(size, align);
s->size = size;
if (forced_order >= 0)
order = forced_order;
else
order = calculate_order(size);
if (order < 0)
return 0;
s->allocflags = 0;
if (order)
s->allocflags |= __GFP_COMP;
if (s->flags & SLAB_CACHE_DMA)
s->allocflags |= SLUB_DMA;
if (s->flags & SLAB_RECLAIM_ACCOUNT)
s->allocflags |= __GFP_RECLAIMABLE;
/*
* Determine the number of objects per slab
*/
s->oo = oo_make(order, size);
s->min = oo_make(get_order(size), size);
if (oo_objects(s->oo) > oo_objects(s->max))
s->max = s->oo;
return !!oo_objects(s->oo);
}
static int kmem_cache_open(struct kmem_cache *s, gfp_t gfpflags,
const char *name, size_t size,
size_t align, unsigned long flags,
void (*ctor)(struct kmem_cache *, void *))
{
memset(s, 0, kmem_size);
s->name = name;
s->ctor = ctor;
s->objsize = size;
s->align = align;
s->flags = kmem_cache_flags(size, flags, name, ctor);
if (!calculate_sizes(s, -1))
goto error;
s->refcount = 1;
#ifdef CONFIG_NUMA
s->remote_node_defrag_ratio = 100;
#endif
if (!init_kmem_cache_nodes(s, gfpflags & ~SLUB_DMA))
goto error;
if (alloc_kmem_cache_cpus(s, gfpflags & ~SLUB_DMA))
return 1;
free_kmem_cache_nodes(s);
error:
if (flags & SLAB_PANIC)
panic("Cannot create slab %s size=%lu realsize=%u "
"order=%u offset=%u flags=%lx\n",
s->name, (unsigned long)size, s->size, oo_order(s->oo),
s->offset, flags);
return 0;
}
/*
* Check if a given pointer is valid
*/
int kmem_ptr_validate(struct kmem_cache *s, const void *object)
{
struct page *page;
page = get_object_page(object);
if (!page || s != page->slab)
/* No slab or wrong slab */
return 0;
if (!check_valid_pointer(s, page, object))
return 0;
/*
* We could also check if the object is on the slabs freelist.
* But this would be too expensive and it seems that the main
* purpose of kmem_ptr_valid() is to check if the object belongs
* to a certain slab.
*/
return 1;
}
EXPORT_SYMBOL(kmem_ptr_validate);
/*
* Determine the size of a slab object
*/
unsigned int kmem_cache_size(struct kmem_cache *s)
{
return s->objsize;
}
EXPORT_SYMBOL(kmem_cache_size);
const char *kmem_cache_name(struct kmem_cache *s)
{
return s->name;
}
EXPORT_SYMBOL(kmem_cache_name);
static void list_slab_objects(struct kmem_cache *s, struct page *page,
const char *text)
{
#ifdef CONFIG_SLUB_DEBUG
void *addr = page_address(page);
void *p;
DECLARE_BITMAP(map, page->objects);
bitmap_zero(map, page->objects);
slab_err(s, page, "%s", text);
slab_lock(page);
for_each_free_object(p, s, page->freelist)
set_bit(slab_index(p, s, addr), map);
for_each_object(p, s, addr, page->objects) {
if (!test_bit(slab_index(p, s, addr), map)) {
printk(KERN_ERR "INFO: Object 0x%p @offset=%tu\n",
p, p - addr);
print_tracking(s, p);
}
}
slab_unlock(page);
#endif
}
/*
* Attempt to free all partial slabs on a node.
*/
static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n)
{
unsigned long flags;
struct page *page, *h;
spin_lock_irqsave(&n->list_lock, flags);
list_for_each_entry_safe(page, h, &n->partial, lru) {
if (!page->inuse) {
list_del(&page->lru);
discard_slab(s, page);
n->nr_partial--;
} else {
list_slab_objects(s, page,
"Objects remaining on kmem_cache_close()");
}
}
spin_unlock_irqrestore(&n->list_lock, flags);
}
/*
* Release all resources used by a slab cache.
*/
static inline int kmem_cache_close(struct kmem_cache *s)
{
int node;
flush_all(s);
/* Attempt to free all objects */
free_kmem_cache_cpus(s);
for_each_node_state(node, N_NORMAL_MEMORY) {
struct kmem_cache_node *n = get_node(s, node);
free_partial(s, n);
if (n->nr_partial || slabs_node(s, node))
return 1;
}
free_kmem_cache_nodes(s);
return 0;
}
/*
* Close a cache and release the kmem_cache structure
* (must be used for caches created using kmem_cache_create)
*/
void kmem_cache_destroy(struct kmem_cache *s)
{
down_write(&slub_lock);
s->refcount--;
if (!s->refcount) {
list_del(&s->list);
up_write(&slub_lock);
if (kmem_cache_close(s)) {
printk(KERN_ERR "SLUB %s: %s called for cache that "
"still has objects.\n", s->name, __func__);
dump_stack();
}
sysfs_slab_remove(s);
} else
up_write(&slub_lock);
}
EXPORT_SYMBOL(kmem_cache_destroy);
/********************************************************************
* Kmalloc subsystem
*******************************************************************/
struct kmem_cache kmalloc_caches[PAGE_SHIFT + 1] __cacheline_aligned;
EXPORT_SYMBOL(kmalloc_caches);
static int __init setup_slub_min_order(char *str)
{
get_option(&str, &slub_min_order);
return 1;
}
__setup("slub_min_order=", setup_slub_min_order);
static int __init setup_slub_max_order(char *str)
{
get_option(&str, &slub_max_order);
return 1;
}
__setup("slub_max_order=", setup_slub_max_order);
static int __init setup_slub_min_objects(char *str)
{
get_option(&str, &slub_min_objects);
return 1;
}
__setup("slub_min_objects=", setup_slub_min_objects);
static int __init setup_slub_nomerge(char *str)
{
slub_nomerge = 1;
return 1;
}
__setup("slub_nomerge", setup_slub_nomerge);
static struct kmem_cache *create_kmalloc_cache(struct kmem_cache *s,
const char *name, int size, gfp_t gfp_flags)
{
unsigned int flags = 0;
if (gfp_flags & SLUB_DMA)
flags = SLAB_CACHE_DMA;
down_write(&slub_lock);
if (!kmem_cache_open(s, gfp_flags, name, size, ARCH_KMALLOC_MINALIGN,
flags, NULL))
goto panic;
list_add(&s->list, &slab_caches);
up_write(&slub_lock);
if (sysfs_slab_add(s))
goto panic;
return s;
panic:
panic("Creation of kmalloc slab %s size=%d failed.\n", name, size);
}
#ifdef CONFIG_ZONE_DMA
static struct kmem_cache *kmalloc_caches_dma[PAGE_SHIFT + 1];
static void sysfs_add_func(struct work_struct *w)
{
struct kmem_cache *s;
down_write(&slub_lock);
list_for_each_entry(s, &slab_caches, list) {
if (s->flags & __SYSFS_ADD_DEFERRED) {
s->flags &= ~__SYSFS_ADD_DEFERRED;
sysfs_slab_add(s);
}
}
up_write(&slub_lock);
}
static DECLARE_WORK(sysfs_add_work, sysfs_add_func);
static noinline struct kmem_cache *dma_kmalloc_cache(int index, gfp_t flags)
{
struct kmem_cache *s;
char *text;
size_t realsize;
s = kmalloc_caches_dma[index];
if (s)
return s;
/* Dynamically create dma cache */
if (flags & __GFP_WAIT)
down_write(&slub_lock);
else {
if (!down_write_trylock(&slub_lock))
goto out;
}
if (kmalloc_caches_dma[index])
goto unlock_out;
realsize = kmalloc_caches[index].objsize;
text = kasprintf(flags & ~SLUB_DMA, "kmalloc_dma-%d",
(unsigned int)realsize);
s = kmalloc(kmem_size, flags & ~SLUB_DMA);
if (!s || !text || !kmem_cache_open(s, flags, text,
realsize, ARCH_KMALLOC_MINALIGN,
SLAB_CACHE_DMA|__SYSFS_ADD_DEFERRED, NULL)) {
kfree(s);
kfree(text);
goto unlock_out;
}
list_add(&s->list, &slab_caches);
kmalloc_caches_dma[index] = s;
schedule_work(&sysfs_add_work);
unlock_out:
up_write(&slub_lock);
out:
return kmalloc_caches_dma[index];
}
#endif
/*
* Conversion table for small slabs sizes / 8 to the index in the
* kmalloc array. This is necessary for slabs < 192 since we have non power
* of two cache sizes there. The size of larger slabs can be determined using
* fls.
*/
static s8 size_index[24] = {
3, /* 8 */
4, /* 16 */
5, /* 24 */
5, /* 32 */
6, /* 40 */
6, /* 48 */
6, /* 56 */
6, /* 64 */
1, /* 72 */
1, /* 80 */
1, /* 88 */
1, /* 96 */
7, /* 104 */
7, /* 112 */
7, /* 120 */
7, /* 128 */
2, /* 136 */
2, /* 144 */
2, /* 152 */
2, /* 160 */
2, /* 168 */
2, /* 176 */
2, /* 184 */
2 /* 192 */
};
static struct kmem_cache *get_slab(size_t size, gfp_t flags)
{
int index;
if (size <= 192) {
if (!size)
return ZERO_SIZE_PTR;
index = size_index[(size - 1) / 8];
} else
index = fls(size - 1);
#ifdef CONFIG_ZONE_DMA
if (unlikely((flags & SLUB_DMA)))
return dma_kmalloc_cache(index, flags);
#endif
return &kmalloc_caches[index];
}
void *__kmalloc(size_t size, gfp_t flags)
{
struct kmem_cache *s;
if (unlikely(size > PAGE_SIZE))
return kmalloc_large(size, flags);
s = get_slab(size, flags);
if (unlikely(ZERO_OR_NULL_PTR(s)))
return s;
return slab_alloc(s, flags, -1, __builtin_return_address(0));
}
EXPORT_SYMBOL(__kmalloc);
static void *kmalloc_large_node(size_t size, gfp_t flags, int node)
{
struct page *page = alloc_pages_node(node, flags | __GFP_COMP,
get_order(size));
if (page)
return page_address(page);
else
return NULL;
}
#ifdef CONFIG_NUMA
void *__kmalloc_node(size_t size, gfp_t flags, int node)
{
struct kmem_cache *s;
if (unlikely(size > PAGE_SIZE))
return kmalloc_large_node(size, flags, node);
s = get_slab(size, flags);
if (unlikely(ZERO_OR_NULL_PTR(s)))
return s;
return slab_alloc(s, flags, node, __builtin_return_address(0));
}
EXPORT_SYMBOL(__kmalloc_node);
#endif
size_t ksize(const void *object)
{
struct page *page;
struct kmem_cache *s;
if (unlikely(object == ZERO_SIZE_PTR))
return 0;
page = virt_to_head_page(object);
if (unlikely(!PageSlab(page)))
return PAGE_SIZE << compound_order(page);
s = page->slab;
#ifdef CONFIG_SLUB_DEBUG
/*
* Debugging requires use of the padding between object
* and whatever may come after it.
*/
if (s->flags & (SLAB_RED_ZONE | SLAB_POISON))
return s->objsize;
#endif
/*
* If we have the need to store the freelist pointer
* back there or track user information then we can
* only use the space before that information.
*/
if (s->flags & (SLAB_DESTROY_BY_RCU | SLAB_STORE_USER))
return s->inuse;
/*
* Else we can use all the padding etc for the allocation
*/
return s->size;
}
EXPORT_SYMBOL(ksize);
void kfree(const void *x)
{
struct page *page;
void *object = (void *)x;
if (unlikely(ZERO_OR_NULL_PTR(x)))
return;
page = virt_to_head_page(x);
if (unlikely(!PageSlab(page))) {
put_page(page);
return;
}
slab_free(page->slab, page, object, __builtin_return_address(0));
}
EXPORT_SYMBOL(kfree);
/*
* kmem_cache_shrink removes empty slabs from the partial lists and sorts
* the remaining slabs by the number of items in use. The slabs with the
* most items in use come first. New allocations will then fill those up
* and thus they can be removed from the partial lists.
*
* The slabs with the least items are placed last. This results in them
* being allocated from last increasing the chance that the last objects
* are freed in them.
*/
int kmem_cache_shrink(struct kmem_cache *s)
{
int node;
int i;
struct kmem_cache_node *n;
struct page *page;
struct page *t;
int objects = oo_objects(s->max);
struct list_head *slabs_by_inuse =
kmalloc(sizeof(struct list_head) * objects, GFP_KERNEL);
unsigned long flags;
if (!slabs_by_inuse)
return -ENOMEM;
flush_all(s);
for_each_node_state(node, N_NORMAL_MEMORY) {
n = get_node(s, node);
if (!n->nr_partial)
continue;
for (i = 0; i < objects; i++)
INIT_LIST_HEAD(slabs_by_inuse + i);
spin_lock_irqsave(&n->list_lock, flags);
/*
* Build lists indexed by the items in use in each slab.
*
* Note that concurrent frees may occur while we hold the
* list_lock. page->inuse here is the upper limit.
*/
list_for_each_entry_safe(page, t, &n->partial, lru) {
if (!page->inuse && slab_trylock(page)) {
/*
* Must hold slab lock here because slab_free
* may have freed the last object and be
* waiting to release the slab.
*/
list_del(&page->lru);
n->nr_partial--;
slab_unlock(page);
discard_slab(s, page);
} else {
list_move(&page->lru,
slabs_by_inuse + page->inuse);
}
}
/*
* Rebuild the partial list with the slabs filled up most
* first and the least used slabs at the end.
*/
for (i = objects - 1; i >= 0; i--)
list_splice(slabs_by_inuse + i, n->partial.prev);
spin_unlock_irqrestore(&n->list_lock, flags);
}
kfree(slabs_by_inuse);
return 0;
}
EXPORT_SYMBOL(kmem_cache_shrink);
#if defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG)
static int slab_mem_going_offline_callback(void *arg)
{
struct kmem_cache *s;
down_read(&slub_lock);
list_for_each_entry(s, &slab_caches, list)
kmem_cache_shrink(s);
up_read(&slub_lock);
return 0;
}
static void slab_mem_offline_callback(void *arg)
{
struct kmem_cache_node *n;
struct kmem_cache *s;
struct memory_notify *marg = arg;
int offline_node;
offline_node = marg->status_change_nid;
/*
* If the node still has available memory. we need kmem_cache_node
* for it yet.
*/
if (offline_node < 0)
return;
down_read(&slub_lock);
list_for_each_entry(s, &slab_caches, list) {
n = get_node(s, offline_node);
if (n) {
/*
* if n->nr_slabs > 0, slabs still exist on the node
* that is going down. We were unable to free them,
* and offline_pages() function shoudn't call this
* callback. So, we must fail.
*/
BUG_ON(slabs_node(s, offline_node));
s->node[offline_node] = NULL;
kmem_cache_free(kmalloc_caches, n);
}
}
up_read(&slub_lock);
}
static int slab_mem_going_online_callback(void *arg)
{
struct kmem_cache_node *n;
struct kmem_cache *s;
struct memory_notify *marg = arg;
int nid = marg->status_change_nid;
int ret = 0;
/*
* If the node's memory is already available, then kmem_cache_node is
* already created. Nothing to do.
*/
if (nid < 0)
return 0;
/*
* We are bringing a node online. No memory is availabe yet. We must
* allocate a kmem_cache_node structure in order to bring the node
* online.
*/
down_read(&slub_lock);
list_for_each_entry(s, &slab_caches, list) {
/*
* XXX: kmem_cache_alloc_node will fallback to other nodes
* since memory is not yet available from the node that
* is brought up.
*/
n = kmem_cache_alloc(kmalloc_caches, GFP_KERNEL);
if (!n) {
ret = -ENOMEM;
goto out;
}
init_kmem_cache_node(n);
s->node[nid] = n;
}
out:
up_read(&slub_lock);
return ret;
}
static int slab_memory_callback(struct notifier_block *self,
unsigned long action, void *arg)
{
int ret = 0;
switch (action) {
case MEM_GOING_ONLINE:
ret = slab_mem_going_online_callback(arg);
break;
case MEM_GOING_OFFLINE:
ret = slab_mem_going_offline_callback(arg);
break;
case MEM_OFFLINE:
case MEM_CANCEL_ONLINE:
slab_mem_offline_callback(arg);
break;
case MEM_ONLINE:
case MEM_CANCEL_OFFLINE:
break;
}
ret = notifier_from_errno(ret);
return ret;
}
#endif /* CONFIG_MEMORY_HOTPLUG */
/********************************************************************
* Basic setup of slabs
*******************************************************************/
void __init kmem_cache_init(void)
{
int i;
int caches = 0;
init_alloc_cpu();
#ifdef CONFIG_NUMA
/*
* Must first have the slab cache available for the allocations of the
* struct kmem_cache_node's. There is special bootstrap code in
* kmem_cache_open for slab_state == DOWN.
*/
create_kmalloc_cache(&kmalloc_caches[0], "kmem_cache_node",
sizeof(struct kmem_cache_node), GFP_KERNEL);
kmalloc_caches[0].refcount = -1;
caches++;
hotplug_memory_notifier(slab_memory_callback, SLAB_CALLBACK_PRI);
#endif
/* Able to allocate the per node structures */
slab_state = PARTIAL;
/* Caches that are not of the two-to-the-power-of size */
if (KMALLOC_MIN_SIZE <= 64) {
create_kmalloc_cache(&kmalloc_caches[1],
"kmalloc-96", 96, GFP_KERNEL);
caches++;
}
if (KMALLOC_MIN_SIZE <= 128) {
create_kmalloc_cache(&kmalloc_caches[2],
"kmalloc-192", 192, GFP_KERNEL);
caches++;
}
for (i = KMALLOC_SHIFT_LOW; i <= PAGE_SHIFT; i++) {
create_kmalloc_cache(&kmalloc_caches[i],
"kmalloc", 1 << i, GFP_KERNEL);
caches++;
}
/*
* Patch up the size_index table if we have strange large alignment
* requirements for the kmalloc array. This is only the case for
* MIPS it seems. The standard arches will not generate any code here.
*
* Largest permitted alignment is 256 bytes due to the way we
* handle the index determination for the smaller caches.
*
* Make sure that nothing crazy happens if someone starts tinkering
* around with ARCH_KMALLOC_MINALIGN
*/
BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
(KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
for (i = 8; i < KMALLOC_MIN_SIZE; i += 8)
size_index[(i - 1) / 8] = KMALLOC_SHIFT_LOW;
slab_state = UP;
/* Provide the correct kmalloc names now that the caches are up */
for (i = KMALLOC_SHIFT_LOW; i <= PAGE_SHIFT; i++)
kmalloc_caches[i]. name =
kasprintf(GFP_KERNEL, "kmalloc-%d", 1 << i);
#ifdef CONFIG_SMP
register_cpu_notifier(&slab_notifier);
kmem_size = offsetof(struct kmem_cache, cpu_slab) +
nr_cpu_ids * sizeof(struct kmem_cache_cpu *);
#else
kmem_size = sizeof(struct kmem_cache);
#endif
printk(KERN_INFO
"SLUB: Genslabs=%d, HWalign=%d, Order=%d-%d, MinObjects=%d,"
" CPUs=%d, Nodes=%d\n",
caches, cache_line_size(),
slub_min_order, slub_max_order, slub_min_objects,
nr_cpu_ids, nr_node_ids);
}
/*
* Find a mergeable slab cache
*/
static int slab_unmergeable(struct kmem_cache *s)
{
if (slub_nomerge || (s->flags & SLUB_NEVER_MERGE))
return 1;
if (s->ctor)
return 1;
/*
* We may have set a slab to be unmergeable during bootstrap.
*/
if (s->refcount < 0)
return 1;
return 0;
}
static struct kmem_cache *find_mergeable(size_t size,
size_t align, unsigned long flags, const char *name,
void (*ctor)(struct kmem_cache *, void *))
{
struct kmem_cache *s;
if (slub_nomerge || (flags & SLUB_NEVER_MERGE))
return NULL;
if (ctor)
return NULL;
size = ALIGN(size, sizeof(void *));
align = calculate_alignment(flags, align, size);
size = ALIGN(size, align);
flags = kmem_cache_flags(size, flags, name, NULL);
list_for_each_entry(s, &slab_caches, list) {
if (slab_unmergeable(s))
continue;
if (size > s->size)
continue;
if ((flags & SLUB_MERGE_SAME) != (s->flags & SLUB_MERGE_SAME))
continue;
/*
* Check if alignment is compatible.
* Courtesy of Adrian Drzewiecki
*/
if ((s->size & ~(align - 1)) != s->size)
continue;
if (s->size - size >= sizeof(void *))
continue;
return s;
}
return NULL;
}
struct kmem_cache *kmem_cache_create(const char *name, size_t size,
size_t align, unsigned long flags,
void (*ctor)(struct kmem_cache *, void *))
{
struct kmem_cache *s;
down_write(&slub_lock);
s = find_mergeable(size, align, flags, name, ctor);
if (s) {
int cpu;
s->refcount++;
/*
* Adjust the object sizes so that we clear
* the complete object on kzalloc.
*/
s->objsize = max(s->objsize, (int)size);
/*
* And then we need to update the object size in the
* per cpu structures
*/
for_each_online_cpu(cpu)
get_cpu_slab(s, cpu)->objsize = s->objsize;
s->inuse = max_t(int, s->inuse, ALIGN(size, sizeof(void *)));
up_write(&slub_lock);
if (sysfs_slab_alias(s, name))
goto err;
return s;
}
s = kmalloc(kmem_size, GFP_KERNEL);
if (s) {
if (kmem_cache_open(s, GFP_KERNEL, name,
size, align, flags, ctor)) {
list_add(&s->list, &slab_caches);
up_write(&slub_lock);
if (sysfs_slab_add(s))
goto err;
return s;
}
kfree(s);
}
up_write(&slub_lock);
err:
if (flags & SLAB_PANIC)
panic("Cannot create slabcache %s\n", name);
else
s = NULL;
return s;
}
EXPORT_SYMBOL(kmem_cache_create);
#ifdef CONFIG_SMP
/*
* Use the cpu notifier to insure that the cpu slabs are flushed when
* necessary.
*/
static int __cpuinit slab_cpuup_callback(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
long cpu = (long)hcpu;
struct kmem_cache *s;
unsigned long flags;
switch (action) {
case CPU_UP_PREPARE:
case CPU_UP_PREPARE_FROZEN:
init_alloc_cpu_cpu(cpu);
down_read(&slub_lock);
list_for_each_entry(s, &slab_caches, list)
s->cpu_slab[cpu] = alloc_kmem_cache_cpu(s, cpu,
GFP_KERNEL);
up_read(&slub_lock);
break;
case CPU_UP_CANCELED:
case CPU_UP_CANCELED_FROZEN:
case CPU_DEAD:
case CPU_DEAD_FROZEN:
down_read(&slub_lock);
list_for_each_entry(s, &slab_caches, list) {
struct kmem_cache_cpu *c = get_cpu_slab(s, cpu);
local_irq_save(flags);
__flush_cpu_slab(s, cpu);
local_irq_restore(flags);
free_kmem_cache_cpu(c, cpu);
s->cpu_slab[cpu] = NULL;
}
up_read(&slub_lock);
break;
default:
break;
}
return NOTIFY_OK;
}
static struct notifier_block __cpuinitdata slab_notifier = {
.notifier_call = slab_cpuup_callback
};
#endif
void *__kmalloc_track_caller(size_t size, gfp_t gfpflags, void *caller)
{
struct kmem_cache *s;
if (unlikely(size > PAGE_SIZE))
return kmalloc_large(size, gfpflags);
s = get_slab(size, gfpflags);
if (unlikely(ZERO_OR_NULL_PTR(s)))
return s;
return slab_alloc(s, gfpflags, -1, caller);
}
void *__kmalloc_node_track_caller(size_t size, gfp_t gfpflags,
int node, void *caller)
{
struct kmem_cache *s;
if (unlikely(size > PAGE_SIZE))
return kmalloc_large_node(size, gfpflags, node);
s = get_slab(size, gfpflags);
if (unlikely(ZERO_OR_NULL_PTR(s)))
return s;
return slab_alloc(s, gfpflags, node, caller);
}
#if (defined(CONFIG_SYSFS) && defined(CONFIG_SLUB_DEBUG)) || defined(CONFIG_SLABINFO)
static unsigned long count_partial(struct kmem_cache_node *n,
int (*get_count)(struct page *))
{
unsigned long flags;
unsigned long x = 0;
struct page *page;
spin_lock_irqsave(&n->list_lock, flags);
list_for_each_entry(page, &n->partial, lru)
x += get_count(page);
spin_unlock_irqrestore(&n->list_lock, flags);
return x;
}
static int count_inuse(struct page *page)
{
return page->inuse;
}
static int count_total(struct page *page)
{
return page->objects;
}
static int count_free(struct page *page)
{
return page->objects - page->inuse;
}
#endif
#if defined(CONFIG_SYSFS) && defined(CONFIG_SLUB_DEBUG)
static int validate_slab(struct kmem_cache *s, struct page *page,
unsigned long *map)
{
void *p;
void *addr = page_address(page);
if (!check_slab(s, page) ||
!on_freelist(s, page, NULL))
return 0;
/* Now we know that a valid freelist exists */
bitmap_zero(map, page->objects);
for_each_free_object(p, s, page->freelist) {
set_bit(slab_index(p, s, addr), map);
if (!check_object(s, page, p, 0))
return 0;
}
for_each_object(p, s, addr, page->objects)
if (!test_bit(slab_index(p, s, addr), map))
if (!check_object(s, page, p, 1))
return 0;
return 1;
}
static void validate_slab_slab(struct kmem_cache *s, struct page *page,
unsigned long *map)
{
if (slab_trylock(page)) {
validate_slab(s, page, map);
slab_unlock(page);
} else
printk(KERN_INFO "SLUB %s: Skipped busy slab 0x%p\n",
s->name, page);
if (s->flags & DEBUG_DEFAULT_FLAGS) {
if (!SlabDebug(page))
printk(KERN_ERR "SLUB %s: SlabDebug not set "
"on slab 0x%p\n", s->name, page);
} else {
if (SlabDebug(page))
printk(KERN_ERR "SLUB %s: SlabDebug set on "
"slab 0x%p\n", s->name, page);
}
}
static int validate_slab_node(struct kmem_cache *s,
struct kmem_cache_node *n, unsigned long *map)
{
unsigned long count = 0;
struct page *page;
unsigned long flags;
spin_lock_irqsave(&n->list_lock, flags);
list_for_each_entry(page, &n->partial, lru) {
validate_slab_slab(s, page, map);
count++;
}
if (count != n->nr_partial)
printk(KERN_ERR "SLUB %s: %ld partial slabs counted but "
"counter=%ld\n", s->name, count, n->nr_partial);
if (!(s->flags & SLAB_STORE_USER))
goto out;
list_for_each_entry(page, &n->full, lru) {
validate_slab_slab(s, page, map);
count++;
}
if (count != atomic_long_read(&n->nr_slabs))
printk(KERN_ERR "SLUB: %s %ld slabs counted but "
"counter=%ld\n", s->name, count,
atomic_long_read(&n->nr_slabs));
out:
spin_unlock_irqrestore(&n->list_lock, flags);
return count;
}
static long validate_slab_cache(struct kmem_cache *s)
{
int node;
unsigned long count = 0;
unsigned long *map = kmalloc(BITS_TO_LONGS(oo_objects(s->max)) *
sizeof(unsigned long), GFP_KERNEL);
if (!map)
return -ENOMEM;
flush_all(s);
for_each_node_state(node, N_NORMAL_MEMORY) {
struct kmem_cache_node *n = get_node(s, node);
count += validate_slab_node(s, n, map);
}
kfree(map);
return count;
}
#ifdef SLUB_RESILIENCY_TEST
static void resiliency_test(void)
{
u8 *p;
printk(KERN_ERR "SLUB resiliency testing\n");
printk(KERN_ERR "-----------------------\n");
printk(KERN_ERR "A. Corruption after allocation\n");
p = kzalloc(16, GFP_KERNEL);
p[16] = 0x12;
printk(KERN_ERR "\n1. kmalloc-16: Clobber Redzone/next pointer"
" 0x12->0x%p\n\n", p + 16);
validate_slab_cache(kmalloc_caches + 4);
/* Hmmm... The next two are dangerous */
p = kzalloc(32, GFP_KERNEL);
p[32 + sizeof(void *)] = 0x34;
printk(KERN_ERR "\n2. kmalloc-32: Clobber next pointer/next slab"
" 0x34 -> -0x%p\n", p);
printk(KERN_ERR
"If allocated object is overwritten then not detectable\n\n");
validate_slab_cache(kmalloc_caches + 5);
p = kzalloc(64, GFP_KERNEL);
p += 64 + (get_cycles() & 0xff) * sizeof(void *);
*p = 0x56;
printk(KERN_ERR "\n3. kmalloc-64: corrupting random byte 0x56->0x%p\n",
p);
printk(KERN_ERR
"If allocated object is overwritten then not detectable\n\n");
validate_slab_cache(kmalloc_caches + 6);
printk(KERN_ERR "\nB. Corruption after free\n");
p = kzalloc(128, GFP_KERNEL);
kfree(p);
*p = 0x78;
printk(KERN_ERR "1. kmalloc-128: Clobber first word 0x78->0x%p\n\n", p);
validate_slab_cache(kmalloc_caches + 7);
p = kzalloc(256, GFP_KERNEL);
kfree(p);
p[50] = 0x9a;
printk(KERN_ERR "\n2. kmalloc-256: Clobber 50th byte 0x9a->0x%p\n\n",
p);
validate_slab_cache(kmalloc_caches + 8);
p = kzalloc(512, GFP_KERNEL);
kfree(p);
p[512] = 0xab;
printk(KERN_ERR "\n3. kmalloc-512: Clobber redzone 0xab->0x%p\n\n", p);
validate_slab_cache(kmalloc_caches + 9);
}
#else
static void resiliency_test(void) {};
#endif
/*
* Generate lists of code addresses where slabcache objects are allocated
* and freed.
*/
struct location {
unsigned long count;
void *addr;
long long sum_time;
long min_time;
long max_time;
long min_pid;
long max_pid;
cpumask_t cpus;
nodemask_t nodes;
};
struct loc_track {
unsigned long max;
unsigned long count;
struct location *loc;
};
static void free_loc_track(struct loc_track *t)
{
if (t->max)
free_pages((unsigned long)t->loc,
get_order(sizeof(struct location) * t->max));
}
static int alloc_loc_track(struct loc_track *t, unsigned long max, gfp_t flags)
{
struct location *l;
int order;
order = get_order(sizeof(struct location) * max);
l = (void *)__get_free_pages(flags, order);
if (!l)
return 0;
if (t->count) {
memcpy(l, t->loc, sizeof(struct location) * t->count);
free_loc_track(t);
}
t->max = max;
t->loc = l;
return 1;
}
static int add_location(struct loc_track *t, struct kmem_cache *s,
const struct track *track)
{
long start, end, pos;
struct location *l;
void *caddr;
unsigned long age = jiffies - track->when;
start = -1;
end = t->count;
for ( ; ; ) {
pos = start + (end - start + 1) / 2;
/*
* There is nothing at "end". If we end up there
* we need to add something to before end.
*/
if (pos == end)
break;
caddr = t->loc[pos].addr;
if (track->addr == caddr) {
l = &t->loc[pos];
l->count++;
if (track->when) {
l->sum_time += age;
if (age < l->min_time)
l->min_time = age;
if (age > l->max_time)
l->max_time = age;
if (track->pid < l->min_pid)
l->min_pid = track->pid;
if (track->pid > l->max_pid)
l->max_pid = track->pid;
cpu_set(track->cpu, l->cpus);
}
node_set(page_to_nid(virt_to_page(track)), l->nodes);
return 1;
}
if (track->addr < caddr)
end = pos;
else
start = pos;
}
/*
* Not found. Insert new tracking element.
*/
if (t->count >= t->max && !alloc_loc_track(t, 2 * t->max, GFP_ATOMIC))
return 0;
l = t->loc + pos;
if (pos < t->count)
memmove(l + 1, l,
(t->count - pos) * sizeof(struct location));
t->count++;
l->count = 1;
l->addr = track->addr;
l->sum_time = age;
l->min_time = age;
l->max_time = age;
l->min_pid = track->pid;
l->max_pid = track->pid;
cpus_clear(l->cpus);
cpu_set(track->cpu, l->cpus);
nodes_clear(l->nodes);
node_set(page_to_nid(virt_to_page(track)), l->nodes);
return 1;
}
static void process_slab(struct loc_track *t, struct kmem_cache *s,
struct page *page, enum track_item alloc)
{
void *addr = page_address(page);
DECLARE_BITMAP(map, page->objects);
void *p;
bitmap_zero(map, page->objects);
for_each_free_object(p, s, page->freelist)
set_bit(slab_index(p, s, addr), map);
for_each_object(p, s, addr, page->objects)
if (!test_bit(slab_index(p, s, addr), map))
add_location(t, s, get_track(s, p, alloc));
}
static int list_locations(struct kmem_cache *s, char *buf,
enum track_item alloc)
{
int len = 0;
unsigned long i;
struct loc_track t = { 0, 0, NULL };
int node;
if (!alloc_loc_track(&t, PAGE_SIZE / sizeof(struct location),
GFP_TEMPORARY))
return sprintf(buf, "Out of memory\n");
/* Push back cpu slabs */
flush_all(s);
for_each_node_state(node, N_NORMAL_MEMORY) {
struct kmem_cache_node *n = get_node(s, node);
unsigned long flags;
struct page *page;
if (!atomic_long_read(&n->nr_slabs))
continue;
spin_lock_irqsave(&n->list_lock, flags);
list_for_each_entry(page, &n->partial, lru)
process_slab(&t, s, page, alloc);
list_for_each_entry(page, &n->full, lru)
process_slab(&t, s, page, alloc);
spin_unlock_irqrestore(&n->list_lock, flags);
}
for (i = 0; i < t.count; i++) {
struct location *l = &t.loc[i];
if (len > PAGE_SIZE - 100)
break;
len += sprintf(buf + len, "%7ld ", l->count);
if (l->addr)
len += sprint_symbol(buf + len, (unsigned long)l->addr);
else
len += sprintf(buf + len, "<not-available>");
if (l->sum_time != l->min_time) {
len += sprintf(buf + len, " age=%ld/%ld/%ld",
l->min_time,
(long)div_u64(l->sum_time, l->count),
l->max_time);
} else
len += sprintf(buf + len, " age=%ld",
l->min_time);
if (l->min_pid != l->max_pid)
len += sprintf(buf + len, " pid=%ld-%ld",
l->min_pid, l->max_pid);
else
len += sprintf(buf + len, " pid=%ld",
l->min_pid);
if (num_online_cpus() > 1 && !cpus_empty(l->cpus) &&
len < PAGE_SIZE - 60) {
len += sprintf(buf + len, " cpus=");
len += cpulist_scnprintf(buf + len, PAGE_SIZE - len - 50,
l->cpus);
}
if (num_online_nodes() > 1 && !nodes_empty(l->nodes) &&
len < PAGE_SIZE - 60) {
len += sprintf(buf + len, " nodes=");
len += nodelist_scnprintf(buf + len, PAGE_SIZE - len - 50,
l->nodes);
}
len += sprintf(buf + len, "\n");
}
free_loc_track(&t);
if (!t.count)
len += sprintf(buf, "No data\n");
return len;
}
enum slab_stat_type {
SL_ALL, /* All slabs */
SL_PARTIAL, /* Only partially allocated slabs */
SL_CPU, /* Only slabs used for cpu caches */
SL_OBJECTS, /* Determine allocated objects not slabs */
SL_TOTAL /* Determine object capacity not slabs */
};
#define SO_ALL (1 << SL_ALL)
#define SO_PARTIAL (1 << SL_PARTIAL)
#define SO_CPU (1 << SL_CPU)
#define SO_OBJECTS (1 << SL_OBJECTS)
#define SO_TOTAL (1 << SL_TOTAL)
static ssize_t show_slab_objects(struct kmem_cache *s,
char *buf, unsigned long flags)
{
unsigned long total = 0;
int node;
int x;
unsigned long *nodes;
unsigned long *per_cpu;
nodes = kzalloc(2 * sizeof(unsigned long) * nr_node_ids, GFP_KERNEL);
if (!nodes)
return -ENOMEM;
per_cpu = nodes + nr_node_ids;
if (flags & SO_CPU) {
int cpu;
for_each_possible_cpu(cpu) {
struct kmem_cache_cpu *c = get_cpu_slab(s, cpu);
if (!c || c->node < 0)
continue;
if (c->page) {
if (flags & SO_TOTAL)
x = c->page->objects;
else if (flags & SO_OBJECTS)
x = c->page->inuse;
else
x = 1;
total += x;
nodes[c->node] += x;
}
per_cpu[c->node]++;
}
}
if (flags & SO_ALL) {
for_each_node_state(node, N_NORMAL_MEMORY) {
struct kmem_cache_node *n = get_node(s, node);
if (flags & SO_TOTAL)
x = atomic_long_read(&n->total_objects);
else if (flags & SO_OBJECTS)
x = atomic_long_read(&n->total_objects) -
count_partial(n, count_free);
else
x = atomic_long_read(&n->nr_slabs);
total += x;
nodes[node] += x;
}
} else if (flags & SO_PARTIAL) {
for_each_node_state(node, N_NORMAL_MEMORY) {
struct kmem_cache_node *n = get_node(s, node);
if (flags & SO_TOTAL)
x = count_partial(n, count_total);
else if (flags & SO_OBJECTS)
x = count_partial(n, count_inuse);
else
x = n->nr_partial;
total += x;
nodes[node] += x;
}
}
x = sprintf(buf, "%lu", total);
#ifdef CONFIG_NUMA
for_each_node_state(node, N_NORMAL_MEMORY)
if (nodes[node])
x += sprintf(buf + x, " N%d=%lu",
node, nodes[node]);
#endif
kfree(nodes);
return x + sprintf(buf + x, "\n");
}
static int any_slab_objects(struct kmem_cache *s)
{
int node;
for_each_online_node(node) {
struct kmem_cache_node *n = get_node(s, node);
if (!n)
continue;
if (atomic_read(&n->total_objects))
return 1;
}
return 0;
}
#define to_slab_attr(n) container_of(n, struct slab_attribute, attr)
#define to_slab(n) container_of(n, struct kmem_cache, kobj);
struct slab_attribute {
struct attribute attr;
ssize_t (*show)(struct kmem_cache *s, char *buf);
ssize_t (*store)(struct kmem_cache *s, const char *x, size_t count);
};
#define SLAB_ATTR_RO(_name) \
static struct slab_attribute _name##_attr = __ATTR_RO(_name)
#define SLAB_ATTR(_name) \
static struct slab_attribute _name##_attr = \
__ATTR(_name, 0644, _name##_show, _name##_store)
static ssize_t slab_size_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", s->size);
}
SLAB_ATTR_RO(slab_size);
static ssize_t align_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", s->align);
}
SLAB_ATTR_RO(align);
static ssize_t object_size_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", s->objsize);
}
SLAB_ATTR_RO(object_size);
static ssize_t objs_per_slab_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", oo_objects(s->oo));
}
SLAB_ATTR_RO(objs_per_slab);
static ssize_t order_store(struct kmem_cache *s,
const char *buf, size_t length)
{
int order = simple_strtoul(buf, NULL, 10);
if (order > slub_max_order || order < slub_min_order)
return -EINVAL;
calculate_sizes(s, order);
return length;
}
static ssize_t order_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", oo_order(s->oo));
}
SLAB_ATTR(order);
static ssize_t ctor_show(struct kmem_cache *s, char *buf)
{
if (s->ctor) {
int n = sprint_symbol(buf, (unsigned long)s->ctor);
return n + sprintf(buf + n, "\n");
}
return 0;
}
SLAB_ATTR_RO(ctor);
static ssize_t aliases_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", s->refcount - 1);
}
SLAB_ATTR_RO(aliases);
static ssize_t slabs_show(struct kmem_cache *s, char *buf)
{
return show_slab_objects(s, buf, SO_ALL);
}
SLAB_ATTR_RO(slabs);
static ssize_t partial_show(struct kmem_cache *s, char *buf)
{
return show_slab_objects(s, buf, SO_PARTIAL);
}
SLAB_ATTR_RO(partial);
static ssize_t cpu_slabs_show(struct kmem_cache *s, char *buf)
{
return show_slab_objects(s, buf, SO_CPU);
}
SLAB_ATTR_RO(cpu_slabs);
static ssize_t objects_show(struct kmem_cache *s, char *buf)
{
return show_slab_objects(s, buf, SO_ALL|SO_OBJECTS);
}
SLAB_ATTR_RO(objects);
static ssize_t objects_partial_show(struct kmem_cache *s, char *buf)
{
return show_slab_objects(s, buf, SO_PARTIAL|SO_OBJECTS);
}
SLAB_ATTR_RO(objects_partial);
static ssize_t total_objects_show(struct kmem_cache *s, char *buf)
{
return show_slab_objects(s, buf, SO_ALL|SO_TOTAL);
}
SLAB_ATTR_RO(total_objects);
static ssize_t sanity_checks_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_DEBUG_FREE));
}
static ssize_t sanity_checks_store(struct kmem_cache *s,
const char *buf, size_t length)
{
s->flags &= ~SLAB_DEBUG_FREE;
if (buf[0] == '1')
s->flags |= SLAB_DEBUG_FREE;
return length;
}
SLAB_ATTR(sanity_checks);
static ssize_t trace_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_TRACE));
}
static ssize_t trace_store(struct kmem_cache *s, const char *buf,
size_t length)
{
s->flags &= ~SLAB_TRACE;
if (buf[0] == '1')
s->flags |= SLAB_TRACE;
return length;
}
SLAB_ATTR(trace);
static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_RECLAIM_ACCOUNT));
}
static ssize_t reclaim_account_store(struct kmem_cache *s,
const char *buf, size_t length)
{
s->flags &= ~SLAB_RECLAIM_ACCOUNT;
if (buf[0] == '1')
s->flags |= SLAB_RECLAIM_ACCOUNT;
return length;
}
SLAB_ATTR(reclaim_account);
static ssize_t hwcache_align_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_HWCACHE_ALIGN));
}
SLAB_ATTR_RO(hwcache_align);
#ifdef CONFIG_ZONE_DMA
static ssize_t cache_dma_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_CACHE_DMA));
}
SLAB_ATTR_RO(cache_dma);
#endif
static ssize_t destroy_by_rcu_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_DESTROY_BY_RCU));
}
SLAB_ATTR_RO(destroy_by_rcu);
static ssize_t red_zone_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_RED_ZONE));
}
static ssize_t red_zone_store(struct kmem_cache *s,
const char *buf, size_t length)
{
if (any_slab_objects(s))
return -EBUSY;
s->flags &= ~SLAB_RED_ZONE;
if (buf[0] == '1')
s->flags |= SLAB_RED_ZONE;
calculate_sizes(s, -1);
return length;
}
SLAB_ATTR(red_zone);
static ssize_t poison_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_POISON));
}
static ssize_t poison_store(struct kmem_cache *s,
const char *buf, size_t length)
{
if (any_slab_objects(s))
return -EBUSY;
s->flags &= ~SLAB_POISON;
if (buf[0] == '1')
s->flags |= SLAB_POISON;
calculate_sizes(s, -1);
return length;
}
SLAB_ATTR(poison);
static ssize_t store_user_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_STORE_USER));
}
static ssize_t store_user_store(struct kmem_cache *s,
const char *buf, size_t length)
{
if (any_slab_objects(s))
return -EBUSY;
s->flags &= ~SLAB_STORE_USER;
if (buf[0] == '1')
s->flags |= SLAB_STORE_USER;
calculate_sizes(s, -1);
return length;
}
SLAB_ATTR(store_user);
static ssize_t validate_show(struct kmem_cache *s, char *buf)
{
return 0;
}
static ssize_t validate_store(struct kmem_cache *s,
const char *buf, size_t length)
{
int ret = -EINVAL;
if (buf[0] == '1') {
ret = validate_slab_cache(s);
if (ret >= 0)
ret = length;
}
return ret;
}
SLAB_ATTR(validate);
static ssize_t shrink_show(struct kmem_cache *s, char *buf)
{
return 0;
}
static ssize_t shrink_store(struct kmem_cache *s,
const char *buf, size_t length)
{
if (buf[0] == '1') {
int rc = kmem_cache_shrink(s);
if (rc)
return rc;
} else
return -EINVAL;
return length;
}
SLAB_ATTR(shrink);
static ssize_t alloc_calls_show(struct kmem_cache *s, char *buf)
{
if (!(s->flags & SLAB_STORE_USER))
return -ENOSYS;
return list_locations(s, buf, TRACK_ALLOC);
}
SLAB_ATTR_RO(alloc_calls);
static ssize_t free_calls_show(struct kmem_cache *s, char *buf)
{
if (!(s->flags & SLAB_STORE_USER))
return -ENOSYS;
return list_locations(s, buf, TRACK_FREE);
}
SLAB_ATTR_RO(free_calls);
#ifdef CONFIG_NUMA
static ssize_t remote_node_defrag_ratio_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", s->remote_node_defrag_ratio / 10);
}
static ssize_t remote_node_defrag_ratio_store(struct kmem_cache *s,
const char *buf, size_t length)
{
int n = simple_strtoul(buf, NULL, 10);
if (n < 100)
s->remote_node_defrag_ratio = n * 10;
return length;
}
SLAB_ATTR(remote_node_defrag_ratio);
#endif
#ifdef CONFIG_SLUB_STATS
static int show_stat(struct kmem_cache *s, char *buf, enum stat_item si)
{
unsigned long sum = 0;
int cpu;
int len;
int *data = kmalloc(nr_cpu_ids * sizeof(int), GFP_KERNEL);
if (!data)
return -ENOMEM;
for_each_online_cpu(cpu) {
unsigned x = get_cpu_slab(s, cpu)->stat[si];
data[cpu] = x;
sum += x;
}
len = sprintf(buf, "%lu", sum);
#ifdef CONFIG_SMP
for_each_online_cpu(cpu) {
if (data[cpu] && len < PAGE_SIZE - 20)
len += sprintf(buf + len, " C%d=%u", cpu, data[cpu]);
}
#endif
kfree(data);
return len + sprintf(buf + len, "\n");
}
#define STAT_ATTR(si, text) \
static ssize_t text##_show(struct kmem_cache *s, char *buf) \
{ \
return show_stat(s, buf, si); \
} \
SLAB_ATTR_RO(text); \
STAT_ATTR(ALLOC_FASTPATH, alloc_fastpath);
STAT_ATTR(ALLOC_SLOWPATH, alloc_slowpath);
STAT_ATTR(FREE_FASTPATH, free_fastpath);
STAT_ATTR(FREE_SLOWPATH, free_slowpath);
STAT_ATTR(FREE_FROZEN, free_frozen);
STAT_ATTR(FREE_ADD_PARTIAL, free_add_partial);
STAT_ATTR(FREE_REMOVE_PARTIAL, free_remove_partial);
STAT_ATTR(ALLOC_FROM_PARTIAL, alloc_from_partial);
STAT_ATTR(ALLOC_SLAB, alloc_slab);
STAT_ATTR(ALLOC_REFILL, alloc_refill);
STAT_ATTR(FREE_SLAB, free_slab);
STAT_ATTR(CPUSLAB_FLUSH, cpuslab_flush);
STAT_ATTR(DEACTIVATE_FULL, deactivate_full);
STAT_ATTR(DEACTIVATE_EMPTY, deactivate_empty);
STAT_ATTR(DEACTIVATE_TO_HEAD, deactivate_to_head);
STAT_ATTR(DEACTIVATE_TO_TAIL, deactivate_to_tail);
STAT_ATTR(DEACTIVATE_REMOTE_FREES, deactivate_remote_frees);
STAT_ATTR(ORDER_FALLBACK, order_fallback);
#endif
static struct attribute *slab_attrs[] = {
&slab_size_attr.attr,
&object_size_attr.attr,
&objs_per_slab_attr.attr,
&order_attr.attr,
&objects_attr.attr,
&objects_partial_attr.attr,
&total_objects_attr.attr,
&slabs_attr.attr,
&partial_attr.attr,
&cpu_slabs_attr.attr,
&ctor_attr.attr,
&aliases_attr.attr,
&align_attr.attr,
&sanity_checks_attr.attr,
&trace_attr.attr,
&hwcache_align_attr.attr,
&reclaim_account_attr.attr,
&destroy_by_rcu_attr.attr,
&red_zone_attr.attr,
&poison_attr.attr,
&store_user_attr.attr,
&validate_attr.attr,
&shrink_attr.attr,
&alloc_calls_attr.attr,
&free_calls_attr.attr,
#ifdef CONFIG_ZONE_DMA
&cache_dma_attr.attr,
#endif
#ifdef CONFIG_NUMA
&remote_node_defrag_ratio_attr.attr,
#endif
#ifdef CONFIG_SLUB_STATS
&alloc_fastpath_attr.attr,
&alloc_slowpath_attr.attr,
&free_fastpath_attr.attr,
&free_slowpath_attr.attr,
&free_frozen_attr.attr,
&free_add_partial_attr.attr,
&free_remove_partial_attr.attr,
&alloc_from_partial_attr.attr,
&alloc_slab_attr.attr,
&alloc_refill_attr.attr,
&free_slab_attr.attr,
&cpuslab_flush_attr.attr,
&deactivate_full_attr.attr,
&deactivate_empty_attr.attr,
&deactivate_to_head_attr.attr,
&deactivate_to_tail_attr.attr,
&deactivate_remote_frees_attr.attr,
&order_fallback_attr.attr,
#endif
NULL
};
static struct attribute_group slab_attr_group = {
.attrs = slab_attrs,
};
static ssize_t slab_attr_show(struct kobject *kobj,
struct attribute *attr,
char *buf)
{
struct slab_attribute *attribute;
struct kmem_cache *s;
int err;
attribute = to_slab_attr(attr);
s = to_slab(kobj);
if (!attribute->show)
return -EIO;
err = attribute->show(s, buf);
return err;
}
static ssize_t slab_attr_store(struct kobject *kobj,
struct attribute *attr,
const char *buf, size_t len)
{
struct slab_attribute *attribute;
struct kmem_cache *s;
int err;
attribute = to_slab_attr(attr);
s = to_slab(kobj);
if (!attribute->store)
return -EIO;
err = attribute->store(s, buf, len);
return err;
}
static void kmem_cache_release(struct kobject *kobj)
{
struct kmem_cache *s = to_slab(kobj);
kfree(s);
}
static struct sysfs_ops slab_sysfs_ops = {
.show = slab_attr_show,
.store = slab_attr_store,
};
static struct kobj_type slab_ktype = {
.sysfs_ops = &slab_sysfs_ops,
.release = kmem_cache_release
};
static int uevent_filter(struct kset *kset, struct kobject *kobj)
{
struct kobj_type *ktype = get_ktype(kobj);
if (ktype == &slab_ktype)
return 1;
return 0;
}
static struct kset_uevent_ops slab_uevent_ops = {
.filter = uevent_filter,
};
static struct kset *slab_kset;
#define ID_STR_LENGTH 64
/* Create a unique string id for a slab cache:
*
* Format :[flags-]size
*/
static char *create_unique_id(struct kmem_cache *s)
{
char *name = kmalloc(ID_STR_LENGTH, GFP_KERNEL);
char *p = name;
BUG_ON(!name);
*p++ = ':';
/*
* First flags affecting slabcache operations. We will only
* get here for aliasable slabs so we do not need to support
* too many flags. The flags here must cover all flags that
* are matched during merging to guarantee that the id is
* unique.
*/
if (s->flags & SLAB_CACHE_DMA)
*p++ = 'd';
if (s->flags & SLAB_RECLAIM_ACCOUNT)
*p++ = 'a';
if (s->flags & SLAB_DEBUG_FREE)
*p++ = 'F';
if (p != name + 1)
*p++ = '-';
p += sprintf(p, "%07d", s->size);
BUG_ON(p > name + ID_STR_LENGTH - 1);
return name;
}
static int sysfs_slab_add(struct kmem_cache *s)
{
int err;
const char *name;
int unmergeable;
if (slab_state < SYSFS)
/* Defer until later */
return 0;
unmergeable = slab_unmergeable(s);
if (unmergeable) {
/*
* Slabcache can never be merged so we can use the name proper.
* This is typically the case for debug situations. In that
* case we can catch duplicate names easily.
*/
sysfs_remove_link(&slab_kset->kobj, s->name);
name = s->name;
} else {
/*
* Create a unique name for the slab as a target
* for the symlinks.
*/
name = create_unique_id(s);
}
s->kobj.kset = slab_kset;
err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, name);
if (err) {
kobject_put(&s->kobj);
return err;
}
err = sysfs_create_group(&s->kobj, &slab_attr_group);
if (err)
return err;
kobject_uevent(&s->kobj, KOBJ_ADD);
if (!unmergeable) {
/* Setup first alias */
sysfs_slab_alias(s, s->name);
kfree(name);
}
return 0;
}
static void sysfs_slab_remove(struct kmem_cache *s)
{
kobject_uevent(&s->kobj, KOBJ_REMOVE);
kobject_del(&s->kobj);
kobject_put(&s->kobj);
}
/*
* Need to buffer aliases during bootup until sysfs becomes
* available lest we loose that information.
*/
struct saved_alias {
struct kmem_cache *s;
const char *name;
struct saved_alias *next;
};
static struct saved_alias *alias_list;
static int sysfs_slab_alias(struct kmem_cache *s, const char *name)
{
struct saved_alias *al;
if (slab_state == SYSFS) {
/*
* If we have a leftover link then remove it.
*/
sysfs_remove_link(&slab_kset->kobj, name);
return sysfs_create_link(&slab_kset->kobj, &s->kobj, name);
}
al = kmalloc(sizeof(struct saved_alias), GFP_KERNEL);
if (!al)
return -ENOMEM;
al->s = s;
al->name = name;
al->next = alias_list;
alias_list = al;
return 0;
}
static int __init slab_sysfs_init(void)
{
struct kmem_cache *s;
int err;
slab_kset = kset_create_and_add("slab", &slab_uevent_ops, kernel_kobj);
if (!slab_kset) {
printk(KERN_ERR "Cannot register slab subsystem.\n");
return -ENOSYS;
}
slab_state = SYSFS;
list_for_each_entry(s, &slab_caches, list) {
err = sysfs_slab_add(s);
if (err)
printk(KERN_ERR "SLUB: Unable to add boot slab %s"
" to sysfs\n", s->name);
}
while (alias_list) {
struct saved_alias *al = alias_list;
alias_list = alias_list->next;
err = sysfs_slab_alias(al->s, al->name);
if (err)
printk(KERN_ERR "SLUB: Unable to add boot slab alias"
" %s to sysfs\n", s->name);
kfree(al);
}
resiliency_test();
return 0;
}
__initcall(slab_sysfs_init);
#endif
/*
* The /proc/slabinfo ABI
*/
#ifdef CONFIG_SLABINFO
ssize_t slabinfo_write(struct file *file, const char __user * buffer,
size_t count, loff_t *ppos)
{
return -EINVAL;
}
static void print_slabinfo_header(struct seq_file *m)
{
seq_puts(m, "slabinfo - version: 2.1\n");
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>");
seq_putc(m, '\n');
}
static void *s_start(struct seq_file *m, loff_t *pos)
{
loff_t n = *pos;
down_read(&slub_lock);
if (!n)
print_slabinfo_header(m);
return seq_list_start(&slab_caches, *pos);
}
static void *s_next(struct seq_file *m, void *p, loff_t *pos)
{
return seq_list_next(p, &slab_caches, pos);
}
static void s_stop(struct seq_file *m, void *p)
{
up_read(&slub_lock);
}
static int s_show(struct seq_file *m, void *p)
{
unsigned long nr_partials = 0;
unsigned long nr_slabs = 0;
unsigned long nr_inuse = 0;
unsigned long nr_objs = 0;
unsigned long nr_free = 0;
struct kmem_cache *s;
int node;
s = list_entry(p, struct kmem_cache, list);
for_each_online_node(node) {
struct kmem_cache_node *n = get_node(s, node);
if (!n)
continue;
nr_partials += n->nr_partial;
nr_slabs += atomic_long_read(&n->nr_slabs);
nr_objs += atomic_long_read(&n->total_objects);
nr_free += count_partial(n, count_free);
}
nr_inuse = nr_objs - nr_free;
seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d", s->name, nr_inuse,
nr_objs, s->size, oo_objects(s->oo),
(1 << oo_order(s->oo)));
seq_printf(m, " : tunables %4u %4u %4u", 0, 0, 0);
seq_printf(m, " : slabdata %6lu %6lu %6lu", nr_slabs, nr_slabs,
0UL);
seq_putc(m, '\n');
return 0;
}
const struct seq_operations slabinfo_op = {
.start = s_start,
.next = s_next,
.stop = s_stop,
.show = s_show,
};
#endif /* CONFIG_SLABINFO */
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