/*
* 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/kallsyms.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.
* There is no list for full slabs. If an object in a full slab is
* freed then the slab will show up again on the partial lists.
* Otherwise there is no need to track full slabs unless we have to
* track full slabs for debugging purposes.
*
* 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 used as a cpu cache. Allocations
* may be performed from the slab. The slab is not
* on any slab list and cannot be moved onto one.
*
* PageError Slab requires special handling due to debug
* options set. This moves slab handling out of
* the fast path.
*/
/*
* Issues still to be resolved:
*
* - The per cpu array is updated for each new slab and and is a remote
* cacheline for most nodes. This could become a bouncing cacheline given
* enough frequent updates. There are 16 pointers in a cacheline.so at
* max 16 cpus could compete. Likely okay.
*
* - Support PAGE_ALLOC_DEBUG. Should be easy to do.
*
* - SLAB_DEBUG_INITIAL is not supported but I have never seen a use of
* it.
*
* - Variable sizing of the per node arrays
*/
/* Enable to test recovery from slab corruption on boot */
#undef SLUB_RESILIENCY_TEST
#if PAGE_SHIFT <= 12
/*
* Small page size. Make sure that we do not fragment memory
*/
#define DEFAULT_MAX_ORDER 1
#define DEFAULT_MIN_OBJECTS 4
#else
/*
* Large page machines are customarily able to handle larger
* page orders.
*/
#define DEFAULT_MAX_ORDER 2
#define DEFAULT_MIN_OBJECTS 8
#endif
/*
* Flags from the regular SLAB that SLUB does not support:
*/
#define SLUB_UNIMPLEMENTED (SLAB_DEBUG_INITIAL)
/*
* 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 2
/*
* 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 */
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 */
SYSFS /* Sysfs up */
} slab_state = DOWN;
/* A list of all slab caches on the system */
static DECLARE_RWSEM(slub_lock);
LIST_HEAD(slab_caches);
#ifdef CONFIG_SYSFS
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 int sysfs_slab_add(struct kmem_cache *s) { return 0; }
static int sysfs_slab_alias(struct kmem_cache *s, const char *p) { return 0; }
static void sysfs_slab_remove(struct kmem_cache *s) {}
#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
}
/*
* 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 "%10s 0x%p: ", text, addr + i);
newline = 0;
}
printk(" %02x", addr[i]);
offset = i % 16;
ascii[offset] = isgraph(addr[i]) ? addr[i] : '.';
if (offset == 15) {
printk(" %s\n",ascii);
newline = 1;
}
}
if (!newline) {
i %= 16;
while (i < 16) {
printk(" ");
ascii[i] = ' ';
i++;
}
printk(" %s\n", ascii);
}
}
/*
* Slow version of get and set free pointer.
*
* This requires touching the cache lines of kmem_cache.
* The offset can also be obtained from the page. In that
* case it is in the cacheline that we already need to touch.
*/
static void *get_freepointer(struct kmem_cache *s, void *object)
{
return *(void **)(object + s->offset);
}
static void set_freepointer(struct kmem_cache *s, void *object, void *fp)
{
*(void **)(object + s->offset) = fp;
}
/*
* 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 };
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) {
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 "%s: ", s);
__print_symbol("%s", (unsigned long)t->addr);
printk(" jiffies_ago=%lu cpu=%u pid=%d\n", jiffies - t->when, t->cpu, t->pid);
}
static void print_trailer(struct kmem_cache *s, u8 *p)
{
unsigned int off; /* Offset of last byte */
if (s->flags & SLAB_RED_ZONE)
print_section("Redzone", p + s->objsize,
s->inuse - s->objsize);
printk(KERN_ERR "FreePointer 0x%p -> 0x%p\n",
p + s->offset,
get_freepointer(s, p));
if (s->offset)
off = s->offset + sizeof(void *);
else
off = s->inuse;
if (s->flags & SLAB_STORE_USER) {
print_track("Last alloc", get_track(s, p, TRACK_ALLOC));
print_track("Last free ", get_track(s, p, TRACK_FREE));
off += 2 * sizeof(struct track);
}
if (off != s->size)
/* Beginning of the filler is the free pointer */
print_section("Filler", p + off, s->size - off);
}
static void object_err(struct kmem_cache *s, struct page *page,
u8 *object, char *reason)
{
u8 *addr = page_address(page);
printk(KERN_ERR "*** SLUB %s: %s@0x%p slab 0x%p\n",
s->name, reason, object, page);
printk(KERN_ERR " offset=%tu flags=0x%04lx inuse=%u freelist=0x%p\n",
object - addr, page->flags, page->inuse, page->freelist);
if (object > addr + 16)
print_section("Bytes b4", object - 16, 16);
print_section("Object", object, min(s->objsize, 128));
print_trailer(s, object);
dump_stack();
}
static void slab_err(struct kmem_cache *s, struct page *page, char *reason, ...)
{
va_list args;
char buf[100];
va_start(args, reason);
vsnprintf(buf, sizeof(buf), reason, args);
va_end(args);
printk(KERN_ERR "*** SLUB %s: %s in slab @0x%p\n", s->name, buf,
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 int check_bytes(u8 *start, unsigned int value, unsigned int bytes)
{
while (bytes) {
if (*start != (u8)value)
return 0;
start++;
bytes--;
}
return 1;
}
static int check_valid_pointer(struct kmem_cache *s, struct page *page,
void *object)
{
void *base;
if (!object)
return 1;
base = page_address(page);
if (object < base || object >= base + s->objects * s->size ||
(object - base) % s->size) {
return 0;
}
return 1;
}
/*
* 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 to word size 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
* A. Free pointer (if we cannot overwrite object on free)
* B. Tracking data for SLAB_STORE_USER
* C. Padding to reach required alignment boundary
* Padding is done using 0x5a (POISON_INUSE)
*
* object + s->size
*
* If slabcaches are merged then the objsize and inuse boundaries are to
* be ignored. And therefore no slab options that rely on these boundaries
* may be used with merged slabcaches.
*/
static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
void *from, void *to)
{
printk(KERN_ERR "@@@ SLUB: %s Restoring %s (0x%x) from 0x%p-0x%p\n",
s->name, message, data, from, to - 1);
memset(from, data, to - from);
}
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;
if (check_bytes(p + off, POISON_INUSE, s->size - off))
return 1;
object_err(s, page, p, "Object padding check fails");
/*
* Restore padding
*/
restore_bytes(s, "object padding", POISON_INUSE, p + off, p + s->size);
return 0;
}
static int slab_pad_check(struct kmem_cache *s, struct page *page)
{
u8 *p;
int length, remainder;
if (!(s->flags & SLAB_POISON))
return 1;
p = page_address(page);
length = s->objects * s->size;
remainder = (PAGE_SIZE << s->order) - length;
if (!remainder)
return 1;
if (!check_bytes(p + length, POISON_INUSE, remainder)) {
printk(KERN_ERR "SLUB: %s slab 0x%p: Padding fails check\n",
s->name, p);
dump_stack();
restore_bytes(s, "slab padding", POISON_INUSE, p + length,
p + length + remainder);
return 0;
}
return 1;
}
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(endobject, red, s->inuse - s->objsize)) {
object_err(s, page, object,
active ? "Redzone Active" : "Redzone Inactive");
restore_bytes(s, "redzone", red,
endobject, object + s->inuse);
return 0;
}
} else {
if ((s->flags & SLAB_POISON) && s->objsize < s->inuse &&
!check_bytes(endobject, POISON_INUSE,
s->inuse - s->objsize)) {
object_err(s, page, p, "Alignment padding check fails");
/*
* Fix it so that there will not be another report.
*
* Hmmm... We may be corrupting an object that now expects
* to be longer than allowed.
*/
restore_bytes(s, "alignment padding", POISON_INUSE,
endobject, object + s->inuse);
}
}
if (s->flags & SLAB_POISON) {
if (!active && (s->flags & __OBJECT_POISON) &&
(!check_bytes(p, POISON_FREE, s->objsize - 1) ||
p[s->objsize - 1] != POISON_END)) {
object_err(s, page, p, "Poison check failed");
restore_bytes(s, "Poison", POISON_FREE,
p, p + s->objsize -1);
restore_bytes(s, "Poison", POISON_END,
p + s->objsize - 1, p + s->objsize);
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 maybe
* wrong now.
*/
set_freepointer(s, p, NULL);
return 0;
}
return 1;
}
static int check_slab(struct kmem_cache *s, struct page *page)
{
VM_BUG_ON(!irqs_disabled());
if (!PageSlab(page)) {
printk(KERN_ERR "SLUB: %s Not a valid slab page @0x%p "
"flags=%lx mapping=0x%p count=%d \n",
s->name, page, page->flags, page->mapping,
page_count(page));
return 0;
}
if (page->offset * sizeof(void *) != s->offset) {
printk(KERN_ERR "SLUB: %s Corrupted offset %lu in slab @0x%p"
" flags=0x%lx mapping=0x%p count=%d\n",
s->name,
(unsigned long)(page->offset * sizeof(void *)),
page,
page->flags,
page->mapping,
page_count(page));
dump_stack();
return 0;
}
if (page->inuse > s->objects) {
printk(KERN_ERR "SLUB: %s Inuse %u > max %u in slab "
"page @0x%p flags=%lx mapping=0x%p count=%d\n",
s->name, page->inuse, s->objects, page, page->flags,
page->mapping, page_count(page));
dump_stack();
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 and
* therefore free. Must hold the slab lock for cpu slabs to
* guarantee that the chains are consistent.
*/
static int on_freelist(struct kmem_cache *s, struct page *page, void *search)
{
int nr = 0;
void *fp = page->freelist;
void *object = NULL;
while (fp && nr <= s->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 {
printk(KERN_ERR "SLUB: %s slab 0x%p "
"freepointer 0x%p corrupted.\n",
s->name, page, fp);
dump_stack();
page->freelist = NULL;
page->inuse = s->objects;
return 0;
}
break;
}
object = fp;
fp = get_freepointer(s, object);
nr++;
}
if (page->inuse != s->objects - nr) {
printk(KERN_ERR "slab %s: page 0x%p wrong object count."
" counter is %d but counted were %d\n",
s->name, page, page->inuse,
s->objects - nr);
page->inuse = s->objects - nr;
}
return search == NULL;
}
/*
* Tracking of fully allocated slabs for debugging
*/
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);
}
static int alloc_object_checks(struct kmem_cache *s, struct page *page,
void *object)
{
if (!check_slab(s, page))
goto bad;
if (object && !on_freelist(s, page, object)) {
printk(KERN_ERR "SLUB: %s Object 0x%p@0x%p "
"already allocated.\n",
s->name, object, page);
goto dump;
}
if (!check_valid_pointer(s, page, object)) {
object_err(s, page, object, "Freelist Pointer check fails");
goto dump;
}
if (!object)
return 1;
if (!check_object(s, page, object, 0))
goto bad;
init_object(s, object, 1);
if (s->flags & SLAB_TRACE) {
printk(KERN_INFO "TRACE %s alloc 0x%p inuse=%d fp=0x%p\n",
s->name, object, page->inuse,
page->freelist);
dump_stack();
}
return 1;
dump:
dump_stack();
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 remainder.
*/
printk(KERN_ERR "@@@ SLUB: %s slab 0x%p. Marking all objects used.\n",
s->name, page);
page->inuse = s->objects;
page->freelist = NULL;
/* Fix up fields that may be corrupted */
page->offset = s->offset / sizeof(void *);
}
return 0;
}
static int free_object_checks(struct kmem_cache *s, struct page *page,
void *object)
{
if (!check_slab(s, page))
goto fail;
if (!check_valid_pointer(s, page, object)) {
printk(KERN_ERR "SLUB: %s slab 0x%p invalid "
"object pointer 0x%p\n",
s->name, page, object);
goto fail;
}
if (on_freelist(s, page, object)) {
printk(KERN_ERR "SLUB: %s slab 0x%p object "
"0x%p already free.\n", s->name, page, object);
goto fail;
}
if (!check_object(s, page, object, 1))
return 0;
if (unlikely(s != page->slab)) {
if (!PageSlab(page))
printk(KERN_ERR "slab_free %s size %d: attempt to"
"free object(0x%p) outside of slab.\n",
s->name, s->size, object);
else
if (!page->slab)
printk(KERN_ERR
"slab_free : no slab(NULL) for object 0x%p.\n",
object);
else
printk(KERN_ERR "slab_free %s(%d): object at 0x%p"
" belongs to slab %s(%d)\n",
s->name, s->size, object,
page->slab->name, page->slab->size);
goto fail;
}
if (s->flags & SLAB_TRACE) {
printk(KERN_INFO "TRACE %s free 0x%p inuse=%d fp=0x%p\n",
s->name, object, page->inuse,
page->freelist);
print_section("Object", object, s->objsize);
dump_stack();
}
init_object(s, object, 0);
return 1;
fail:
dump_stack();
printk(KERN_ERR "@@@ SLUB: %s slab 0x%p object at 0x%p not freed.\n",
s->name, page, object);
return 0;
}
/*
* Slab allocation and freeing
*/
static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
{
struct page * page;
int pages = 1 << s->order;
if (s->order)
flags |= __GFP_COMP;
if (s->flags & SLAB_CACHE_DMA)
flags |= SLUB_DMA;
if (node == -1)
page = alloc_pages(flags, s->order);
else
page = alloc_pages_node(node, flags, s->order);
if (!page)
return NULL;
mod_zone_page_state(page_zone(page),
(s->flags & SLAB_RECLAIM_ACCOUNT) ?
NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
pages);
return page;
}
static void setup_object(struct kmem_cache *s, struct page *page,
void *object)
{
if (PageError(page)) {
init_object(s, object, 0);
init_tracking(s, object);
}
if (unlikely(s->ctor)) {
int mode = SLAB_CTOR_CONSTRUCTOR;
if (!(s->flags & __GFP_WAIT))
mode |= SLAB_CTOR_ATOMIC;
s->ctor(object, s, mode);
}
}
static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
{
struct page *page;
struct kmem_cache_node *n;
void *start;
void *end;
void *last;
void *p;
if (flags & __GFP_NO_GROW)
return NULL;
BUG_ON(flags & ~(GFP_DMA | GFP_LEVEL_MASK));
if (flags & __GFP_WAIT)
local_irq_enable();
page = allocate_slab(s, flags & GFP_LEVEL_MASK, node);
if (!page)
goto out;
n = get_node(s, page_to_nid(page));
if (n)
atomic_long_inc(&n->nr_slabs);
page->offset = s->offset / sizeof(void *);
page->slab = s;
page->flags |= 1 << PG_slab;
if (s->flags & (SLAB_DEBUG_FREE | SLAB_RED_ZONE | SLAB_POISON |
SLAB_STORE_USER | SLAB_TRACE))
page->flags |= 1 << PG_error;
start = page_address(page);
end = start + s->objects * s->size;
if (unlikely(s->flags & SLAB_POISON))
memset(start, POISON_INUSE, PAGE_SIZE << s->order);
last = start;
for (p = start + s->size; p < end; p += s->size) {
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:
if (flags & __GFP_WAIT)
local_irq_disable();
return page;
}
static void __free_slab(struct kmem_cache *s, struct page *page)
{
int pages = 1 << s->order;
if (unlikely(PageError(page) || s->dtor)) {
void *start = page_address(page);
void *end = start + (pages << PAGE_SHIFT);
void *p;
slab_pad_check(s, page);
for (p = start; p <= end - s->size; p += s->size) {
if (s->dtor)
s->dtor(p, s, 0);
check_object(s, page, p, 0);
}
}
mod_zone_page_state(page_zone(page),
(s->flags & SLAB_RECLAIM_ACCOUNT) ?
NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
- pages);
page->mapping = NULL;
__free_pages(page, s->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)
{
struct kmem_cache_node *n = get_node(s, page_to_nid(page));
atomic_long_dec(&n->nr_slabs);
reset_page_mapcount(page);
page->flags &= ~(1 << PG_slab | 1 << PG_error);
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_tail(struct kmem_cache_node *n, struct page *page)
{
spin_lock(&n->list_lock);
n->nr_partial++;
list_add_tail(&page->lru, &n->partial);
spin_unlock(&n->list_lock);
}
static void add_partial(struct kmem_cache_node *n, struct page *page)
{
spin_lock(&n->list_lock);
n->nr_partial++;
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 page and remove it from the partial list
*
* Must hold list_lock
*/
static int lock_and_del_slab(struct kmem_cache_node *n, struct page *page)
{
if (slab_trylock(page)) {
list_del(&page->lru);
n->nr_partial--;
return 1;
}
return 0;
}
/*
* Try to get 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 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_del_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 zone **z;
struct page *page;
/*
* The defrag ratio allows to configure the tradeoffs between
* inter node defragmentation and node local allocations.
* A lower defrag_ratio increases the tendency to do local
* allocations instead of scanning throught the partial
* lists on other nodes.
*
* If defrag_ratio is set to 0 then kmalloc() always
* returns node local objects. If its higher then kmalloc()
* may return off node objects in order to avoid fragmentation.
*
* A higher ratio means slabs may be taken from other nodes
* thus reducing the number of partial slabs on those nodes.
*
* If /sys/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 a bit expensive to do on every slab allocation.
*/
if (!s->defrag_ratio || get_cycles() % 1024 > s->defrag_ratio)
return NULL;
zonelist = &NODE_DATA(slab_node(current->mempolicy))
->node_zonelists[gfp_zone(flags)];
for (z = zonelist->zones; *z; z++) {
struct kmem_cache_node *n;
n = get_node(s, zone_to_nid(*z));
if (n && cpuset_zone_allowed_hardwall(*z, 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 putback_slab(struct kmem_cache *s, struct page *page)
{
struct kmem_cache_node *n = get_node(s, page_to_nid(page));
if (page->inuse) {
if (page->freelist)
add_partial(n, page);
else if (PageError(page) && (s->flags & SLAB_STORE_USER))
add_full(n, page);
slab_unlock(page);
} else {
if (n->nr_partial < MIN_PARTIAL) {
/*
* Adding an empty page to the partial slabs in order
* to avoid page allocator overhead. This page needs to
* come after all the others that are not fully empty
* in order to make sure that we do maximum
* defragmentation.
*/
add_partial_tail(n, page);
slab_unlock(page);
} else {
slab_unlock(page);
discard_slab(s, page);
}
}
}
/*
* Remove the cpu slab
*/
static void deactivate_slab(struct kmem_cache *s, struct page *page, int cpu)
{
s->cpu_slab[cpu] = NULL;
ClearPageActive(page);
putback_slab(s, page);
}
static void flush_slab(struct kmem_cache *s, struct page *page, int cpu)
{
slab_lock(page);
deactivate_slab(s, page, cpu);
}
/*
* Flush cpu slab.
* Called from IPI handler with interrupts disabled.
*/
static void __flush_cpu_slab(struct kmem_cache *s, int cpu)
{
struct page *page = s->cpu_slab[cpu];
if (likely(page))
flush_slab(s, page, cpu);
}
static void flush_cpu_slab(void *d)
{
struct kmem_cache *s = d;
int cpu = smp_processor_id();
__flush_cpu_slab(s, cpu);
}
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
}
/*
* slab_alloc is optimized to only modify two cachelines on the fast path
* (aside from the stack):
*
* 1. The page struct
* 2. The first cacheline of the object to be allocated.
*
* The only cache lines that are read (apart from code) is the
* per cpu array in the kmem_cache struct.
*
* Fastpath is not possible if we need to get a new slab or have
* debugging enabled (which means all slabs are marked with PageError)
*/
static void *slab_alloc(struct kmem_cache *s,
gfp_t gfpflags, int node, void *addr)
{
struct page *page;
void **object;
unsigned long flags;
int cpu;
local_irq_save(flags);
cpu = smp_processor_id();
page = s->cpu_slab[cpu];
if (!page)
goto new_slab;
slab_lock(page);
if (unlikely(node != -1 && page_to_nid(page) != node))
goto another_slab;
redo:
object = page->freelist;
if (unlikely(!object))
goto another_slab;
if (unlikely(PageError(page)))
goto debug;
have_object:
page->inuse++;
page->freelist = object[page->offset];
slab_unlock(page);
local_irq_restore(flags);
return object;
another_slab:
deactivate_slab(s, page, cpu);
new_slab:
page = get_partial(s, gfpflags, node);
if (likely(page)) {
have_slab:
s->cpu_slab[cpu] = page;
SetPageActive(page);
goto redo;
}
page = new_slab(s, gfpflags, node);
if (page) {
cpu = smp_processor_id();
if (s->cpu_slab[cpu]) {
/*
* Someone else populated the cpu_slab while we enabled
* interrupts, or we have got scheduled on another cpu.
* The page may not be on the requested node.
*/
if (node == -1 ||
page_to_nid(s->cpu_slab[cpu]) == node) {
/*
* Current cpuslab is acceptable and we
* want the current one since its cache hot
*/
discard_slab(s, page);
page = s->cpu_slab[cpu];
slab_lock(page);
goto redo;
}
/* Dump the current slab */
flush_slab(s, s->cpu_slab[cpu], cpu);
}
slab_lock(page);
goto have_slab;
}
local_irq_restore(flags);
return NULL;
debug:
if (!alloc_object_checks(s, page, object))
goto another_slab;
if (s->flags & SLAB_STORE_USER)
set_track(s, object, TRACK_ALLOC, addr);
goto have_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
/*
* The fastpath only writes the cacheline of the page struct and the first
* cacheline of the object.
*
* No special cachelines need to be read
*/
static void slab_free(struct kmem_cache *s, struct page *page,
void *x, void *addr)
{
void *prior;
void **object = (void *)x;
unsigned long flags;
local_irq_save(flags);
slab_lock(page);
if (unlikely(PageError(page)))
goto debug;
checks_ok:
prior = object[page->offset] = page->freelist;
page->freelist = object;
page->inuse--;
if (unlikely(PageActive(page)))
/*
* Cpu slabs are never on partial lists and are
* never freed.
*/
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);
out_unlock:
slab_unlock(page);
local_irq_restore(flags);
return;
slab_empty:
if (prior)
/*
* Slab on the partial list.
*/
remove_partial(s, page);
slab_unlock(page);
discard_slab(s, page);
local_irq_restore(flags);
return;
debug:
if (!free_object_checks(s, page, x))
goto out_unlock;
if (!PageActive(page) && !page->freelist)
remove_full(s, page);
if (s->flags & SLAB_STORE_USER)
set_track(s, x, TRACK_FREE, addr);
goto checks_ok;
}
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;
}
/*
* kmem_cache_open produces objects aligned at "size" and the first object
* is placed at offset 0 in the slab (We have no metainformation on the
* slab, all slabs are in essence "off slab").
*
* In order to get the desired alignment one just needs to align the
* size.
*
* 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 therefore may influence
* locking overhead.
*
* The offset is used to relocate the free list link in each object. It is
* therefore possible to move the free list link behind the object. This
* is necessary for RCU to work properly and also useful for debugging.
*/
/*
* 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 = DEFAULT_MAX_ORDER;
/*
* Minimum number of objects per slab. This is necessary in order to
* reduce locking overhead. Similar to the queue size in SLAB.
*/
static int slub_min_objects = DEFAULT_MIN_OBJECTS;
/*
* Merge control. If this is set then no merging of slab caches will occur.
*/
static int slub_nomerge;
/*
* Debug settings:
*/
static int slub_debug;
static char *slub_debug_slabs;
/*
* Calculate the order of allocation given an slab object size.
*
* The order of allocation has significant impact on other elements
* of the system. Generally order 0 allocations should be preferred
* since they do not cause fragmentation in the page allocator. Larger
* objects may have problems with order 0 because there may be too much
* space left unused in a slab. We go to a higher order if more than 1/8th
* 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. This is less a
* concern for large slabs though. slub_max_order specifies the order
* where we begin to stop considering the number of objects in a slab.
*
* 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 zero.
*/
static int calculate_order(int size)
{
int order;
int rem;
for (order = max(slub_min_order, fls(size - 1) - PAGE_SHIFT);
order < MAX_ORDER; order++) {
unsigned long slab_size = PAGE_SIZE << order;
if (slub_max_order > order &&
slab_size < slub_min_objects * size)
continue;
if (slab_size < size)
continue;
rem = slab_size % size;
if (rem <= (PAGE_SIZE << order) / 8)
break;
}
if (order >= MAX_ORDER)
return -E2BIG;
return order;
}
/*
* Function to figure out which alignment to use from the
* various ways of specifying it.
*/
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_MUST_HWCACHE_ALIGN | SLAB_HWCACHE_ALIGN)) &&
size > L1_CACHE_BYTES / 2)
return max_t(unsigned long, align, L1_CACHE_BYTES);
if (align < ARCH_SLAB_MINALIGN)
return ARCH_SLAB_MINALIGN;
return ALIGN(align, sizeof(void *));
}
static void init_kmem_cache_node(struct kmem_cache_node *n)
{
n->nr_partial = 0;
atomic_long_set(&n->nr_slabs, 0);
spin_lock_init(&n->list_lock);
INIT_LIST_HEAD(&n->partial);
INIT_LIST_HEAD(&n->full);
}
#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.
*/
static struct kmem_cache_node * __init early_kmem_cache_node_alloc(gfp_t gfpflags,
int node)
{
struct page *page;
struct kmem_cache_node *n;
BUG_ON(kmalloc_caches->size < sizeof(struct kmem_cache_node));
page = new_slab(kmalloc_caches, gfpflags | GFP_THISNODE, node);
/* new_slab() disables interupts */
local_irq_enable();
BUG_ON(!page);
n = page->freelist;
BUG_ON(!n);
page->freelist = get_freepointer(kmalloc_caches, n);
page->inuse++;
kmalloc_caches->node[node] = n;
init_object(kmalloc_caches, n, 1);
init_kmem_cache_node(n);
atomic_long_inc(&n->nr_slabs);
add_partial(n, page);
return n;
}
static void free_kmem_cache_nodes(struct kmem_cache *s)
{
int node;
for_each_online_node(node) {
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_online_node(node) {
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)
{
unsigned long flags = s->flags;
unsigned long size = s->objsize;
unsigned long align = s->align;
/*
* 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->dtor)
s->flags |= __OBJECT_POISON;
else
s->flags &= ~__OBJECT_POISON;
/*
* 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 *));
/*
* 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, so that we can establish a redzone between
* the object and the freepointer to be able to check for overwrites.
*/
if ((flags & SLAB_RED_ZONE) && size == s->objsize)
size += sizeof(void *);
/*
* With that we have determined how much of the slab is 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 || s->dtor)) {
/*
* 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 *);
}
if (flags & SLAB_STORE_USER)
/*
* Need to store information about allocs and frees after
* the object.
*/
size += 2 * sizeof(struct track);
if (flags & DEBUG_DEFAULT_FLAGS)
/*
* 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 *);
/*
* Determine the alignment based on various parameters that the
* user specified (this is unecessarily complex due to the attempt
* to be compatible with SLAB. Should be cleaned up some day).
*/
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;
s->order = calculate_order(size);
if (s->order < 0)
return 0;
/*
* Determine the number of objects per slab
*/
s->objects = (PAGE_SIZE << s->order) / size;
/*
* Verify that the number of objects is within permitted limits.
* The page->inuse field is only 16 bit wide! So we cannot have
* more than 64k objects per slab.
*/
if (!s->objects || s->objects > 65535)
return 0;
return 1;
}
static int __init finish_bootstrap(void)
{
struct list_head *h;
int err;
slab_state = SYSFS;
list_for_each(h, &slab_caches) {
struct kmem_cache *s =
container_of(h, struct kmem_cache, list);
err = sysfs_slab_add(s);
BUG_ON(err);
}
return 0;
}
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)(void *, struct kmem_cache *, unsigned long),
void (*dtor)(void *, struct kmem_cache *, unsigned long))
{
memset(s, 0, kmem_size);
s->name = name;
s->ctor = ctor;
s->dtor = dtor;
s->objsize = size;
s->flags = flags;
s->align = align;
BUG_ON(flags & SLUB_UNIMPLEMENTED);
/*
* The page->offset field is only 16 bit wide. This is an offset
* in units of words from the beginning of an object. If the slab
* size is bigger then we cannot move the free pointer behind the
* object anymore.
*
* On 32 bit platforms the limit is 256k. On 64bit platforms
* the limit is 512k.
*
* Debugging or ctor/dtors may create a need to move the free
* pointer. Fail if this happens.
*/
if (s->size >= 65535 * sizeof(void *)) {
BUG_ON(flags & (SLAB_RED_ZONE | SLAB_POISON |
SLAB_STORE_USER | SLAB_DESTROY_BY_RCU));
BUG_ON(ctor || dtor);
}
else
/*
* Enable debugging if selected on the kernel commandline.
*/
if (slub_debug && (!slub_debug_slabs ||
strncmp(slub_debug_slabs, name,
strlen(slub_debug_slabs)) == 0))
s->flags |= slub_debug;
if (!calculate_sizes(s))
goto error;
s->refcount = 1;
#ifdef CONFIG_NUMA
s->defrag_ratio = 100;
#endif
if (init_kmem_cache_nodes(s, gfpflags & ~SLUB_DMA))
return 1;
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, s->order,
s->offset, flags);
return 0;
}
EXPORT_SYMBOL(kmem_cache_open);
/*
* Check if a given pointer is valid
*/
int kmem_ptr_validate(struct kmem_cache *s, const void *object)
{
struct page * page;
void *addr;
page = get_object_page(object);
if (!page || s != page->slab)
/* No slab or wrong slab */
return 0;
addr = page_address(page);
if (object < addr || object >= addr + s->objects * s->size)
/* Out of bounds */
return 0;
if ((object - addr) % s->size)
/* Improperly aligned */
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);
/*
* Attempt to free all slabs on a node
*/
static int free_list(struct kmem_cache *s, struct kmem_cache_node *n,
struct list_head *list)
{
int slabs_inuse = 0;
unsigned long flags;
struct page *page, *h;
spin_lock_irqsave(&n->list_lock, flags);
list_for_each_entry_safe(page, h, list, lru)
if (!page->inuse) {
list_del(&page->lru);
discard_slab(s, page);
} else
slabs_inuse++;
spin_unlock_irqrestore(&n->list_lock, flags);
return slabs_inuse;
}
/*
* Release all resources used by slab cache
*/
static int kmem_cache_close(struct kmem_cache *s)
{
int node;
flush_all(s);
/* Attempt to free all objects */
for_each_online_node(node) {
struct kmem_cache_node *n = get_node(s, node);
n->nr_partial -= free_list(s, n, &n->partial);
if (atomic_long_read(&n->nr_slabs))
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);
if (kmem_cache_close(s))
WARN_ON(1);
sysfs_slab_remove(s);
kfree(s);
}
up_write(&slub_lock);
}
EXPORT_SYMBOL(kmem_cache_destroy);
/********************************************************************
* Kmalloc subsystem
*******************************************************************/
struct kmem_cache kmalloc_caches[KMALLOC_SHIFT_HIGH + 1] __cacheline_aligned;
EXPORT_SYMBOL(kmalloc_caches);
#ifdef CONFIG_ZONE_DMA
static struct kmem_cache *kmalloc_caches_dma[KMALLOC_SHIFT_HIGH + 1];
#endif
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 int __init setup_slub_debug(char *str)
{
if (!str || *str != '=')
slub_debug = DEBUG_DEFAULT_FLAGS;
else {
str++;
if (*str == 0 || *str == ',')
slub_debug = DEBUG_DEFAULT_FLAGS;
else
for( ;*str && *str != ','; str++)
switch (*str) {
case 'f' : case 'F' :
slub_debug |= SLAB_DEBUG_FREE;
break;
case 'z' : case 'Z' :
slub_debug |= SLAB_RED_ZONE;
break;
case 'p' : case 'P' :
slub_debug |= SLAB_POISON;
break;
case 'u' : case 'U' :
slub_debug |= SLAB_STORE_USER;
break;
case 't' : case 'T' :
slub_debug |= SLAB_TRACE;
break;
default:
printk(KERN_ERR "slub_debug option '%c' "
"unknown. skipped\n",*str);
}
}
if (*str == ',')
slub_debug_slabs = str + 1;
return 1;
}
__setup("slub_debug", setup_slub_debug);
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, 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);
}
static struct kmem_cache *get_slab(size_t size, gfp_t flags)
{
int index = kmalloc_index(size);
if (!index)
return NULL;
/* Allocation too large? */
BUG_ON(index < 0);
#ifdef CONFIG_ZONE_DMA
if ((flags & SLUB_DMA)) {
struct kmem_cache *s;
struct kmem_cache *x;
char *text;
size_t realsize;
s = kmalloc_caches_dma[index];
if (s)
return s;
/* Dynamically create dma cache */
x = kmalloc(kmem_size, flags & ~SLUB_DMA);
if (!x)
panic("Unable to allocate memory for dma cache\n");
if (index <= KMALLOC_SHIFT_HIGH)
realsize = 1 << index;
else {
if (index == 1)
realsize = 96;
else
realsize = 192;
}
text = kasprintf(flags & ~SLUB_DMA, "kmalloc_dma-%d",
(unsigned int)realsize);
s = create_kmalloc_cache(x, text, realsize, flags);
kmalloc_caches_dma[index] = s;
return s;
}
#endif
return &kmalloc_caches[index];
}
void *__kmalloc(size_t size, gfp_t flags)
{
struct kmem_cache *s = get_slab(size, flags);
if (s)
return slab_alloc(s, flags, -1, __builtin_return_address(0));
return NULL;
}
EXPORT_SYMBOL(__kmalloc);
#ifdef CONFIG_NUMA
void *__kmalloc_node(size_t size, gfp_t flags, int node)
{
struct kmem_cache *s = get_slab(size, flags);
if (s)
return slab_alloc(s, flags, node, __builtin_return_address(0));
return NULL;
}
EXPORT_SYMBOL(__kmalloc_node);
#endif
size_t ksize(const void *object)
{
struct page *page = get_object_page(object);
struct kmem_cache *s;
BUG_ON(!page);
s = page->slab;
BUG_ON(!s);
/*
* 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;
/*
* 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 kmem_cache *s;
struct page *page;
if (!x)
return;
page = virt_to_head_page(x);
s = page->slab;
slab_free(s, page, (void *)x, __builtin_return_address(0));
}
EXPORT_SYMBOL(kfree);
/*
* kmem_cache_shrink removes empty slabs from the partial lists
* and then sorts the partially allocated slabs by the number
* of items in use. The slabs with the most items in use
* come first. New allocations will remove these from the
* partial list because they are full. The slabs with the
* least items are placed last. If it happens that the objects
* are freed then the page can be returned to the page allocator.
*/
int kmem_cache_shrink(struct kmem_cache *s)
{
int node;
int i;
struct kmem_cache_node *n;
struct page *page;
struct page *t;
struct list_head *slabs_by_inuse =
kmalloc(sizeof(struct list_head) * s->objects, GFP_KERNEL);
unsigned long flags;
if (!slabs_by_inuse)
return -ENOMEM;
flush_all(s);
for_each_online_node(node) {
n = get_node(s, node);
if (!n->nr_partial)
continue;
for (i = 0; i < s->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 or free slabs if empty.
*
* 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 {
if (n->nr_partial > MAX_PARTIAL)
list_move(&page->lru,
slabs_by_inuse + page->inuse);
}
}
if (n->nr_partial <= MAX_PARTIAL)
goto out;
/*
* Rebuild the partial list with the slabs filled up
* most first and the least used slabs at the end.
*/
for (i = s->objects - 1; i >= 0; i--)
list_splice(slabs_by_inuse + i, n->partial.prev);
out:
spin_unlock_irqrestore(&n->list_lock, flags);
}
kfree(slabs_by_inuse);
return 0;
}
EXPORT_SYMBOL(kmem_cache_shrink);
/**
* krealloc - reallocate memory. The contents will remain unchanged.
*
* @p: object to reallocate memory for.
* @new_size: how many bytes of memory are required.
* @flags: the type of memory to allocate.
*
* The contents of the object pointed to are preserved up to the
* lesser of the new and old sizes. If @p is %NULL, krealloc()
* behaves exactly like kmalloc(). If @size is 0 and @p is not a
* %NULL pointer, the object pointed to is freed.
*/
void *krealloc(const void *p, size_t new_size, gfp_t flags)
{
struct kmem_cache *new_cache;
void *ret;
struct page *page;
if (unlikely(!p))
return kmalloc(new_size, flags);
if (unlikely(!new_size)) {
kfree(p);
return NULL;
}
page = virt_to_head_page(p);
new_cache = get_slab(new_size, flags);
/*
* If new size fits in the current cache, bail out.
*/
if (likely(page->slab == new_cache))
return (void *)p;
ret = kmalloc(new_size, flags);
if (ret) {
memcpy(ret, p, min(new_size, ksize(p)));
kfree(p);
}
return ret;
}
EXPORT_SYMBOL(krealloc);
/********************************************************************
* Basic setup of slabs
*******************************************************************/
void __init kmem_cache_init(void)
{
int i;
#ifdef CONFIG_NUMA
/*
* Must first have the slab cache available for the allocations of the
* struct kmalloc_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);
#endif
/* Able to allocate the per node structures */
slab_state = PARTIAL;
/* Caches that are not of the two-to-the-power-of size */
create_kmalloc_cache(&kmalloc_caches[1],
"kmalloc-96", 96, GFP_KERNEL);
create_kmalloc_cache(&kmalloc_caches[2],
"kmalloc-192", 192, GFP_KERNEL);
for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++)
create_kmalloc_cache(&kmalloc_caches[i],
"kmalloc", 1 << i, GFP_KERNEL);
slab_state = UP;
/* Provide the correct kmalloc names now that the caches are up */
for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++)
kmalloc_caches[i]. name =
kasprintf(GFP_KERNEL, "kmalloc-%d", 1 << i);
#ifdef CONFIG_SMP
register_cpu_notifier(&slab_notifier);
#endif
if (nr_cpu_ids) /* Remove when nr_cpu_ids is fixed upstream ! */
kmem_size = offsetof(struct kmem_cache, cpu_slab)
+ nr_cpu_ids * sizeof(struct page *);
printk(KERN_INFO "SLUB: Genslabs=%d, HWalign=%d, Order=%d-%d, MinObjects=%d,"
" Processors=%d, Nodes=%d\n",
KMALLOC_SHIFT_HIGH, L1_CACHE_BYTES,
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 || s->dtor)
return 1;
return 0;
}
static struct kmem_cache *find_mergeable(size_t size,
size_t align, unsigned long flags,
void (*ctor)(void *, struct kmem_cache *, unsigned long),
void (*dtor)(void *, struct kmem_cache *, unsigned long))
{
struct list_head *h;
if (slub_nomerge || (flags & SLUB_NEVER_MERGE))
return NULL;
if (ctor || dtor)
return NULL;
size = ALIGN(size, sizeof(void *));
align = calculate_alignment(flags, align, size);
size = ALIGN(size, align);
list_for_each(h, &slab_caches) {
struct kmem_cache *s =
container_of(h, struct kmem_cache, list);
if (slab_unmergeable(s))
continue;
if (size > s->size)
continue;
if (((flags | slub_debug) & 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)(void *, struct kmem_cache *, unsigned long),
void (*dtor)(void *, struct kmem_cache *, unsigned long))
{
struct kmem_cache *s;
down_write(&slub_lock);
s = find_mergeable(size, align, flags, dtor, ctor);
if (s) {
s->refcount++;
/*
* Adjust the object sizes so that we clear
* the complete object on kzalloc.
*/
s->objsize = max(s->objsize, (int)size);
s->inuse = max_t(int, s->inuse, ALIGN(size, sizeof(void *)));
if (sysfs_slab_alias(s, name))
goto err;
} else {
s = kmalloc(kmem_size, GFP_KERNEL);
if (s && kmem_cache_open(s, GFP_KERNEL, name,
size, align, flags, ctor, dtor)) {
if (sysfs_slab_add(s)) {
kfree(s);
goto err;
}
list_add(&s->list, &slab_caches);
} else
kfree(s);
}
up_write(&slub_lock);
return s;
err:
up_write(&slub_lock);
if (flags & SLAB_PANIC)
panic("Cannot create slabcache %s\n", name);
else
s = NULL;
return s;
}
EXPORT_SYMBOL(kmem_cache_create);
void *kmem_cache_zalloc(struct kmem_cache *s, gfp_t flags)
{
void *x;
x = slab_alloc(s, flags, -1, __builtin_return_address(0));
if (x)
memset(x, 0, s->objsize);
return x;
}
EXPORT_SYMBOL(kmem_cache_zalloc);
#ifdef CONFIG_SMP
static void for_all_slabs(void (*func)(struct kmem_cache *, int), int cpu)
{
struct list_head *h;
down_read(&slub_lock);
list_for_each(h, &slab_caches) {
struct kmem_cache *s =
container_of(h, struct kmem_cache, list);
func(s, cpu);
}
up_read(&slub_lock);
}
/*
* Use the cpu notifier to insure that the slab are flushed
* when necessary.
*/
static int __cpuinit slab_cpuup_callback(struct notifier_block *nfb,
unsigned long action, void *hcpu)
{
long cpu = (long)hcpu;
switch (action) {
case CPU_UP_CANCELED:
case CPU_DEAD:
for_all_slabs(__flush_cpu_slab, cpu);
break;
default:
break;
}
return NOTIFY_OK;
}
static struct notifier_block __cpuinitdata slab_notifier =
{ &slab_cpuup_callback, NULL, 0 };
#endif
#ifdef CONFIG_NUMA
/*****************************************************************
* Generic reaper used to support the page allocator
* (the cpu slabs are reaped by a per slab workqueue).
*
* Maybe move this to the page allocator?
****************************************************************/
static DEFINE_PER_CPU(unsigned long, reap_node);
static void init_reap_node(int cpu)
{
int node;
node = next_node(cpu_to_node(cpu), node_online_map);
if (node == MAX_NUMNODES)
node = first_node(node_online_map);
__get_cpu_var(reap_node) = node;
}
static void next_reap_node(void)
{
int node = __get_cpu_var(reap_node);
/*
* Also drain per cpu pages on remote zones
*/
if (node != numa_node_id())
drain_node_pages(node);
node = next_node(node, node_online_map);
if (unlikely(node >= MAX_NUMNODES))
node = first_node(node_online_map);
__get_cpu_var(reap_node) = node;
}
#else
#define init_reap_node(cpu) do { } while (0)
#define next_reap_node(void) do { } while (0)
#endif
#define REAPTIMEOUT_CPUC (2*HZ)
#ifdef CONFIG_SMP
static DEFINE_PER_CPU(struct delayed_work, reap_work);
static void cache_reap(struct work_struct *unused)
{
next_reap_node();
refresh_cpu_vm_stats(smp_processor_id());
schedule_delayed_work(&__get_cpu_var(reap_work),
REAPTIMEOUT_CPUC);
}
static void __devinit start_cpu_timer(int cpu)
{
struct delayed_work *reap_work = &per_cpu(reap_work, cpu);
/*
* When this gets called from do_initcalls via cpucache_init(),
* init_workqueues() has already run, so keventd will be setup
* at that time.
*/
if (keventd_up() && reap_work->work.func == NULL) {
init_reap_node(cpu);
INIT_DELAYED_WORK(reap_work, cache_reap);
schedule_delayed_work_on(cpu, reap_work, HZ + 3 * cpu);
}
}
static int __init cpucache_init(void)
{
int cpu;
/*
* Register the timers that drain pcp pages and update vm statistics
*/
for_each_online_cpu(cpu)
start_cpu_timer(cpu);
return 0;
}
__initcall(cpucache_init);
#endif
#ifdef SLUB_RESILIENCY_TEST
static unsigned long validate_slab_cache(struct kmem_cache *s);
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
/*
* These are not as efficient as kmalloc for the non debug case.
* We do not have the page struct available so we have to touch one
* cacheline in struct kmem_cache to check slab flags.
*/
void *__kmalloc_track_caller(size_t size, gfp_t gfpflags, void *caller)
{
struct kmem_cache *s = get_slab(size, gfpflags);
if (!s)
return NULL;
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 = get_slab(size, gfpflags);
if (!s)
return NULL;
return slab_alloc(s, gfpflags, node, caller);
}
#ifdef CONFIG_SYSFS
static int validate_slab(struct kmem_cache *s, struct page *page)
{
void *p;
void *addr = page_address(page);
unsigned long map[BITS_TO_LONGS(s->objects)];
if (!check_slab(s, page) ||
!on_freelist(s, page, NULL))
return 0;
/* Now we know that a valid freelist exists */
bitmap_zero(map, s->objects);
for(p = page->freelist; p; p = get_freepointer(s, p)) {
set_bit((p - addr) / s->size, map);
if (!check_object(s, page, p, 0))
return 0;
}
for(p = addr; p < addr + s->objects * s->size; p += s->size)
if (!test_bit((p - addr) / s->size, map))
if (!check_object(s, page, p, 1))
return 0;
return 1;
}
static void validate_slab_slab(struct kmem_cache *s, struct page *page)
{
if (slab_trylock(page)) {
validate_slab(s, page);
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 (!PageError(page))
printk(KERN_ERR "SLUB %s: PageError not set "
"on slab 0x%p\n", s->name, page);
} else {
if (PageError(page))
printk(KERN_ERR "SLUB %s: PageError 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 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);
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);
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 unsigned long validate_slab_cache(struct kmem_cache *s)
{
int node;
unsigned long count = 0;
flush_all(s);
for_each_online_node(node) {
struct kmem_cache_node *n = get_node(s, node);
count += validate_slab_node(s, n);
}
return count;
}
/*
* Generate lists of locations where slabcache objects are allocated
* and freed.
*/
struct location {
unsigned long count;
void *addr;
};
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)
{
struct location *l;
int order;
if (!max)
max = PAGE_SIZE / sizeof(struct location);
order = get_order(sizeof(struct location) * max);
l = (void *)__get_free_pages(GFP_KERNEL, 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,
void *addr)
{
long start, end, pos;
struct location *l;
void *caddr;
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 (addr == caddr) {
t->loc[pos].count++;
return 1;
}
if (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))
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 = addr;
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);
unsigned long map[BITS_TO_LONGS(s->objects)];
void *p;
bitmap_zero(map, s->objects);
for (p = page->freelist; p; p = get_freepointer(s, p))
set_bit((p - addr) / s->size, map);
for (p = addr; p < addr + s->objects * s->size; p += s->size)
if (!test_bit((p - addr) / s->size, map)) {
void *addr = get_track(s, p, alloc)->addr;
add_location(t, s, addr);
}
}
static int list_locations(struct kmem_cache *s, char *buf,
enum track_item alloc)
{
int n = 0;
unsigned long i;
struct loc_track t;
int node;
t.count = 0;
t.max = 0;
/* Push back cpu slabs */
flush_all(s);
for_each_online_node(node) {
struct kmem_cache_node *n = get_node(s, node);
unsigned long flags;
struct page *page;
if (!atomic_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++) {
void *addr = t.loc[i].addr;
if (n > PAGE_SIZE - 100)
break;
n += sprintf(buf + n, "%7ld ", t.loc[i].count);
if (addr)
n += sprint_symbol(buf + n, (unsigned long)t.loc[i].addr);
else
n += sprintf(buf + n, "<not-available>");
n += sprintf(buf + n, "\n");
}
free_loc_track(&t);
if (!t.count)
n += sprintf(buf, "No data\n");
return n;
}
static unsigned long count_partial(struct kmem_cache_node *n)
{
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 += page->inuse;
spin_unlock_irqrestore(&n->list_lock, flags);
return x;
}
enum slab_stat_type {
SL_FULL,
SL_PARTIAL,
SL_CPU,
SL_OBJECTS
};
#define SO_FULL (1 << SL_FULL)
#define SO_PARTIAL (1 << SL_PARTIAL)
#define SO_CPU (1 << SL_CPU)
#define SO_OBJECTS (1 << SL_OBJECTS)
static unsigned long slab_objects(struct kmem_cache *s,
char *buf, unsigned long flags)
{
unsigned long total = 0;
int cpu;
int node;
int x;
unsigned long *nodes;
unsigned long *per_cpu;
nodes = kzalloc(2 * sizeof(unsigned long) * nr_node_ids, GFP_KERNEL);
per_cpu = nodes + nr_node_ids;
for_each_possible_cpu(cpu) {
struct page *page = s->cpu_slab[cpu];
int node;
if (page) {
node = page_to_nid(page);
if (flags & SO_CPU) {
int x = 0;
if (flags & SO_OBJECTS)
x = page->inuse;
else
x = 1;
total += x;
nodes[node] += x;
}
per_cpu[node]++;
}
}
for_each_online_node(node) {
struct kmem_cache_node *n = get_node(s, node);
if (flags & SO_PARTIAL) {
if (flags & SO_OBJECTS)
x = count_partial(n);
else
x = n->nr_partial;
total += x;
nodes[node] += x;
}
if (flags & SO_FULL) {
int full_slabs = atomic_read(&n->nr_slabs)
- per_cpu[node]
- n->nr_partial;
if (flags & SO_OBJECTS)
x = full_slabs * s->objects;
else
x = full_slabs;
total += x;
nodes[node] += x;
}
}
x = sprintf(buf, "%lu", total);
#ifdef CONFIG_NUMA
for_each_online_node(node)
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;
int cpu;
for_each_possible_cpu(cpu)
if (s->cpu_slab[cpu])
return 1;
for_each_node(node) {
struct kmem_cache_node *n = get_node(s, node);
if (n->nr_partial || atomic_read(&n->nr_slabs))
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", s->objects);
}
SLAB_ATTR_RO(objs_per_slab);
static ssize_t order_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", s->order);
}
SLAB_ATTR_RO(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 dtor_show(struct kmem_cache *s, char *buf)
{
if (s->dtor) {
int n = sprint_symbol(buf, (unsigned long)s->dtor);
return n + sprintf(buf + n, "\n");
}
return 0;
}
SLAB_ATTR_RO(dtor);
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 slab_objects(s, buf, SO_FULL|SO_PARTIAL|SO_CPU);
}
SLAB_ATTR_RO(slabs);
static ssize_t partial_show(struct kmem_cache *s, char *buf)
{
return slab_objects(s, buf, SO_PARTIAL);
}
SLAB_ATTR_RO(partial);
static ssize_t cpu_slabs_show(struct kmem_cache *s, char *buf)
{
return slab_objects(s, buf, SO_CPU);
}
SLAB_ATTR_RO(cpu_slabs);
static ssize_t objects_show(struct kmem_cache *s, char *buf)
{
return slab_objects(s, buf, SO_FULL|SO_PARTIAL|SO_CPU|SO_OBJECTS);
}
SLAB_ATTR_RO(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_MUST_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);
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);
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);
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)
{
if (buf[0] == '1')
validate_slab_cache(s);
else
return -EINVAL;
return length;
}
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 defrag_ratio_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", s->defrag_ratio / 10);
}
static ssize_t defrag_ratio_store(struct kmem_cache *s,
const char *buf, size_t length)
{
int n = simple_strtoul(buf, NULL, 10);
if (n < 100)
s->defrag_ratio = n * 10;
return length;
}
SLAB_ATTR(defrag_ratio);
#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,
&slabs_attr.attr,
&partial_attr.attr,
&cpu_slabs_attr.attr,
&ctor_attr.attr,
&dtor_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
&defrag_ratio_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 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,
};
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,
};
decl_subsys(slab, &slab_ktype, &slab_uevent_ops);
#define ID_STR_LENGTH 64
/* Create a unique string id for a slab cache:
* format
* :[flags-]size:[memory address of kmemcache]
*/
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_subsys.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);
}
kobj_set_kset_s(s, slab_subsys);
kobject_set_name(&s->kobj, name);
kobject_init(&s->kobj);
err = kobject_add(&s->kobj);
if (err)
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);
}
/*
* 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;
};
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_subsys.kset.kobj, name);
return sysfs_create_link(&slab_subsys.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)
{
int err;
err = subsystem_register(&slab_subsys);
if (err) {
printk(KERN_ERR "Cannot register slab subsystem.\n");
return -ENOSYS;
}
finish_bootstrap();
while (alias_list) {
struct saved_alias *al = alias_list;
alias_list = alias_list->next;
err = sysfs_slab_alias(al->s, al->name);
BUG_ON(err);
kfree(al);
}
resiliency_test();
return 0;
}
__initcall(slab_sysfs_init);
#else
__initcall(finish_bootstrap);
#endif
