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linux/mm/slub.c

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// SPDX-License-Identifier: GPL-2.0
/*
* 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 or atomic operatios
* and only uses a centralized lock to manage a pool of partial slabs.
*
* (C) 2007 SGI, Christoph Lameter
* (C) 2011 Linux Foundation, Christoph Lameter
*/
#include <linux/mm.h>
#include <linux/swap.h> /* struct reclaim_state */
#include <linux/module.h>
#include <linux/bit_spinlock.h>
#include <linux/interrupt.h>
#include <linux/bitops.h>
#include <linux/slab.h>
#include "slab.h"
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/kasan.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>
#include <linux/fault-inject.h>
#include <linux/stacktrace.h>
#include <linux/prefetch.h>
#include <linux/memcontrol.h>
#include <linux/random.h>
#include <trace/events/kmem.h>
#include "internal.h"
/*
* Lock order:
* 1. slab_mutex (Global Mutex)
* 2. node->list_lock
* 3. slab_lock(page) (Only on some arches and for debugging)
*
* slab_mutex
*
* The role of the slab_mutex is to protect the list of all the slabs
* and to synchronize major metadata changes to slab cache structures.
*
* The slab_lock is only used for debugging and on arches that do not
* have the ability to do a cmpxchg_double. It only protects:
* A. page->freelist -> List of object free in a page
* B. page->inuse -> Number of objects in use
* C. page->objects -> Number of objects in page
* D. page->frozen -> frozen state
*
* If a slab is frozen then it is exempt from list management. It is not
* on any list except per cpu partial list. The processor that froze the
* slab is the one who can perform list operations on the page. Other
* processors may put objects onto the freelist but the processor that
* froze the slab is the only one that can retrieve the objects from the
* page's freelist.
*
* 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.
* 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.
*
* page->frozen 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.
*
* SLAB_DEBUG_FLAGS Slab requires special handling due to debug
* options set. This moves slab handling out of
* the fast path and disables lockless freelists.
*/
#ifdef CONFIG_SLUB_DEBUG
#ifdef CONFIG_SLUB_DEBUG_ON
DEFINE_STATIC_KEY_TRUE(slub_debug_enabled);
#else
DEFINE_STATIC_KEY_FALSE(slub_debug_enabled);
#endif
#endif
static inline bool kmem_cache_debug(struct kmem_cache *s)
{
return kmem_cache_debug_flags(s, SLAB_DEBUG_FLAGS);
}
void *fixup_red_left(struct kmem_cache *s, void *p)
{
if (kmem_cache_debug_flags(s, SLAB_RED_ZONE))
p += s->red_left_pad;
return p;
}
static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s)
{
#ifdef CONFIG_SLUB_CPU_PARTIAL
return !kmem_cache_debug(s);
#else
return false;
#endif
}
/*
* 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
/* Enable to log cmpxchg failures */
#undef SLUB_DEBUG_CMPXCHG
/*
* 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 use.
*/
#define MAX_PARTIAL 10
#define DEBUG_DEFAULT_FLAGS (SLAB_CONSISTENCY_CHECKS | SLAB_RED_ZONE | \
SLAB_POISON | SLAB_STORE_USER)
/*
* These debug flags cannot use CMPXCHG because there might be consistency
* issues when checking or reading debug information
*/
#define SLAB_NO_CMPXCHG (SLAB_CONSISTENCY_CHECKS | SLAB_STORE_USER | \
SLAB_TRACE)
/*
* Debugging flags that require metadata to be stored in the slab. These get
* disabled when slub_debug=O is used and a cache's min order increases with
* metadata.
*/
#define DEBUG_METADATA_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)
#define OO_SHIFT 16
#define OO_MASK ((1 << OO_SHIFT) - 1)
#define MAX_OBJS_PER_PAGE 32767 /* since page.objects is u15 */
/* Internal SLUB flags */
/* Poison object */
#define __OBJECT_POISON ((slab_flags_t __force)0x80000000U)
/* Use cmpxchg_double */
#define __CMPXCHG_DOUBLE ((slab_flags_t __force)0x40000000U)
/*
* Tracking user of a slab.
*/
#define TRACK_ADDRS_COUNT 16
struct track {
unsigned long addr; /* Called from address */
#ifdef CONFIG_STACKTRACE
unsigned long addrs[TRACK_ADDRS_COUNT]; /* Called from address */
#endif
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 };
#ifdef CONFIG_SYSFS
static int sysfs_slab_add(struct kmem_cache *);
static int sysfs_slab_alias(struct kmem_cache *, const char *);
#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; }
#endif
static inline void stat(const struct kmem_cache *s, enum stat_item si)
{
#ifdef CONFIG_SLUB_STATS
/*
* The rmw is racy on a preemptible kernel but this is acceptable, so
* avoid this_cpu_add()'s irq-disable overhead.
*/
raw_cpu_inc(s->cpu_slab->stat[si]);
#endif
}
/********************************************************************
* Core slab cache functions
*******************************************************************/
/*
* Returns freelist pointer (ptr). With hardening, this is obfuscated
* with an XOR of the address where the pointer is held and a per-cache
* random number.
*/
static inline void *freelist_ptr(const struct kmem_cache *s, void *ptr,
unsigned long ptr_addr)
{
#ifdef CONFIG_SLAB_FREELIST_HARDENED
/*
* When CONFIG_KASAN_SW_TAGS is enabled, ptr_addr might be tagged.
* Normally, this doesn't cause any issues, as both set_freepointer()
* and get_freepointer() are called with a pointer with the same tag.
* However, there are some issues with CONFIG_SLUB_DEBUG code. For
* example, when __free_slub() iterates over objects in a cache, it
* passes untagged pointers to check_object(). check_object() in turns
* calls get_freepointer() with an untagged pointer, which causes the
* freepointer to be restored incorrectly.
*/
return (void *)((unsigned long)ptr ^ s->random ^
swab((unsigned long)kasan_reset_tag((void *)ptr_addr)));
#else
return ptr;
#endif
}
/* Returns the freelist pointer recorded at location ptr_addr. */
static inline void *freelist_dereference(const struct kmem_cache *s,
void *ptr_addr)
{
return freelist_ptr(s, (void *)*(unsigned long *)(ptr_addr),
(unsigned long)ptr_addr);
}
static inline void *get_freepointer(struct kmem_cache *s, void *object)
{
return freelist_dereference(s, object + s->offset);
}
static void prefetch_freepointer(const struct kmem_cache *s, void *object)
{
prefetch(object + s->offset);
}
static inline void *get_freepointer_safe(struct kmem_cache *s, void *object)
{
unsigned long freepointer_addr;
void *p;
if (!debug_pagealloc_enabled_static())
return get_freepointer(s, object);
freepointer_addr = (unsigned long)object + s->offset;
copy_from_kernel_nofault(&p, (void **)freepointer_addr, sizeof(p));
return freelist_ptr(s, p, freepointer_addr);
}
static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp)
{
unsigned long freeptr_addr = (unsigned long)object + s->offset;
#ifdef CONFIG_SLAB_FREELIST_HARDENED
BUG_ON(object == fp); /* naive detection of double free or corruption */
#endif
*(void **)freeptr_addr = freelist_ptr(s, fp, freeptr_addr);
}
/* Loop over all objects in a slab */
#define for_each_object(__p, __s, __addr, __objects) \
for (__p = fixup_red_left(__s, __addr); \
__p < (__addr) + (__objects) * (__s)->size; \
__p += (__s)->size)
static inline unsigned int order_objects(unsigned int order, unsigned int size)
{
return ((unsigned int)PAGE_SIZE << order) / size;
}
static inline struct kmem_cache_order_objects oo_make(unsigned int order,
unsigned int size)
{
struct kmem_cache_order_objects x = {
(order << OO_SHIFT) + order_objects(order, size)
};
return x;
}
static inline unsigned int oo_order(struct kmem_cache_order_objects x)
{
return x.x >> OO_SHIFT;
}
static inline unsigned int oo_objects(struct kmem_cache_order_objects x)
{
return x.x & OO_MASK;
}
/*
* Per slab locking using the pagelock
*/
static __always_inline void slab_lock(struct page *page)
{
VM_BUG_ON_PAGE(PageTail(page), page);
bit_spin_lock(PG_locked, &page->flags);
}
static __always_inline void slab_unlock(struct page *page)
{
VM_BUG_ON_PAGE(PageTail(page), page);
__bit_spin_unlock(PG_locked, &page->flags);
}
/* Interrupts must be disabled (for the fallback code to work right) */
static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
void *freelist_old, unsigned long counters_old,
void *freelist_new, unsigned long counters_new,
const char *n)
{
VM_BUG_ON(!irqs_disabled());
#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
if (s->flags & __CMPXCHG_DOUBLE) {
if (cmpxchg_double(&page->freelist, &page->counters,
freelist_old, counters_old,
freelist_new, counters_new))
return true;
} else
#endif
{
slab_lock(page);
if (page->freelist == freelist_old &&
page->counters == counters_old) {
page->freelist = freelist_new;
page->counters = counters_new;
slab_unlock(page);
return true;
}
slab_unlock(page);
}
cpu_relax();
stat(s, CMPXCHG_DOUBLE_FAIL);
#ifdef SLUB_DEBUG_CMPXCHG
pr_info("%s %s: cmpxchg double redo ", n, s->name);
#endif
return false;
}
static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
void *freelist_old, unsigned long counters_old,
void *freelist_new, unsigned long counters_new,
const char *n)
{
#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
if (s->flags & __CMPXCHG_DOUBLE) {
if (cmpxchg_double(&page->freelist, &page->counters,
freelist_old, counters_old,
freelist_new, counters_new))
return true;
} else
#endif
{
unsigned long flags;
local_irq_save(flags);
slab_lock(page);
if (page->freelist == freelist_old &&
page->counters == counters_old) {
page->freelist = freelist_new;
page->counters = counters_new;
slab_unlock(page);
local_irq_restore(flags);
return true;
}
slab_unlock(page);
local_irq_restore(flags);
}
cpu_relax();
stat(s, CMPXCHG_DOUBLE_FAIL);
#ifdef SLUB_DEBUG_CMPXCHG
pr_info("%s %s: cmpxchg double redo ", n, s->name);
#endif
return false;
}
#ifdef CONFIG_SLUB_DEBUG
static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)];
static DEFINE_SPINLOCK(object_map_lock);
/*
* Determine a map of object in use on a page.
*
* Node listlock must be held to guarantee that the page does
* not vanish from under us.
*/
static unsigned long *get_map(struct kmem_cache *s, struct page *page)
__acquires(&object_map_lock)
{
void *p;
void *addr = page_address(page);
VM_BUG_ON(!irqs_disabled());
spin_lock(&object_map_lock);
bitmap_zero(object_map, page->objects);
for (p = page->freelist; p; p = get_freepointer(s, p))
set_bit(__obj_to_index(s, addr, p), object_map);
return object_map;
}
static void put_map(unsigned long *map) __releases(&object_map_lock)
{
VM_BUG_ON(map != object_map);
spin_unlock(&object_map_lock);
}
static inline unsigned int size_from_object(struct kmem_cache *s)
{
if (s->flags & SLAB_RED_ZONE)
return s->size - s->red_left_pad;
return s->size;
}
static inline void *restore_red_left(struct kmem_cache *s, void *p)
{
if (s->flags & SLAB_RED_ZONE)
p -= s->red_left_pad;
return p;
}
/*
* Debug settings:
*/
#if defined(CONFIG_SLUB_DEBUG_ON)
static slab_flags_t slub_debug = DEBUG_DEFAULT_FLAGS;
#else
static slab_flags_t slub_debug;
#endif
static char *slub_debug_string;
static int disable_higher_order_debug;
/*
* slub is about to manipulate internal object metadata. This memory lies
* outside the range of the allocated object, so accessing it would normally
* be reported by kasan as a bounds error. metadata_access_enable() is used
* to tell kasan that these accesses are OK.
*/
static inline void metadata_access_enable(void)
{
kasan_disable_current();
}
static inline void metadata_access_disable(void)
{
kasan_enable_current();
}
/*
* Object debugging
*/
/* 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, void *object)
{
void *base;
if (!object)
return 1;
base = page_address(page);
object = kasan_reset_tag(object);
object = restore_red_left(s, object);
if (object < base || object >= base + page->objects * s->size ||
(object - base) % s->size) {
return 0;
}
return 1;
}
static void print_section(char *level, char *text, u8 *addr,
unsigned int length)
{
metadata_access_enable();
print_hex_dump(level, text, DUMP_PREFIX_ADDRESS, 16, 1, addr,
length, 1);
metadata_access_disable();
}
/*
* See comment in calculate_sizes().
*/
static inline bool freeptr_outside_object(struct kmem_cache *s)
{
return s->offset >= s->inuse;
}
/*
* Return offset of the end of info block which is inuse + free pointer if
* not overlapping with object.
*/
static inline unsigned int get_info_end(struct kmem_cache *s)
{
if (freeptr_outside_object(s))
return s->inuse + sizeof(void *);
else
return s->inuse;
}
static struct track *get_track(struct kmem_cache *s, void *object,
enum track_item alloc)
{
struct track *p;
p = object + get_info_end(s);
return p + alloc;
}
static void set_track(struct kmem_cache *s, void *object,
enum track_item alloc, unsigned long addr)
{
struct track *p = get_track(s, object, alloc);
if (addr) {
#ifdef CONFIG_STACKTRACE
unsigned int nr_entries;
metadata_access_enable();
nr_entries = stack_trace_save(p->addrs, TRACK_ADDRS_COUNT, 3);
metadata_access_disable();
if (nr_entries < TRACK_ADDRS_COUNT)
p->addrs[nr_entries] = 0;
#endif
p->addr = addr;
p->cpu = smp_processor_id();
p->pid = current->pid;
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, 0UL);
set_track(s, object, TRACK_ALLOC, 0UL);
}
static void print_track(const char *s, struct track *t, unsigned long pr_time)
{
if (!t->addr)
return;
pr_err("INFO: %s in %pS age=%lu cpu=%u pid=%d\n",
s, (void *)t->addr, pr_time - t->when, t->cpu, t->pid);
#ifdef CONFIG_STACKTRACE
{
int i;
for (i = 0; i < TRACK_ADDRS_COUNT; i++)
if (t->addrs[i])
pr_err("\t%pS\n", (void *)t->addrs[i]);
else
break;
}
#endif
}
void print_tracking(struct kmem_cache *s, void *object)
{
unsigned long pr_time = jiffies;
if (!(s->flags & SLAB_STORE_USER))
return;
print_track("Allocated", get_track(s, object, TRACK_ALLOC), pr_time);
print_track("Freed", get_track(s, object, TRACK_FREE), pr_time);
}
static void print_page_info(struct page *page)
{
pr_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, ...)
{
struct va_format vaf;
va_list args;
va_start(args, fmt);
vaf.fmt = fmt;
vaf.va = &args;
pr_err("=============================================================================\n");
pr_err("BUG %s (%s): %pV\n", s->name, print_tainted(), &vaf);
pr_err("-----------------------------------------------------------------------------\n\n");
add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
va_end(args);
}
static void slab_fix(struct kmem_cache *s, char *fmt, ...)
{
struct va_format vaf;
va_list args;
va_start(args, fmt);
vaf.fmt = fmt;
vaf.va = &args;
pr_err("FIX %s: %pV\n", s->name, &vaf);
va_end(args);
}
static bool freelist_corrupted(struct kmem_cache *s, struct page *page,
void **freelist, void *nextfree)
{
if ((s->flags & SLAB_CONSISTENCY_CHECKS) &&
!check_valid_pointer(s, page, nextfree) && freelist) {
object_err(s, page, *freelist, "Freechain corrupt");
*freelist = NULL;
slab_fix(s, "Isolate corrupted freechain");
return true;
}
return false;
}
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);
pr_err("INFO: Object 0x%p @offset=%tu fp=0x%p\n\n",
p, p - addr, get_freepointer(s, p));
if (s->flags & SLAB_RED_ZONE)
print_section(KERN_ERR, "Redzone ", p - s->red_left_pad,
s->red_left_pad);
else if (p > addr + 16)
print_section(KERN_ERR, "Bytes b4 ", p - 16, 16);
print_section(KERN_ERR, "Object ", p,
min_t(unsigned int, s->object_size, PAGE_SIZE));
if (s->flags & SLAB_RED_ZONE)
print_section(KERN_ERR, "Redzone ", p + s->object_size,
s->inuse - s->object_size);
off = get_info_end(s);
if (s->flags & SLAB_STORE_USER)
off += 2 * sizeof(struct track);
off += kasan_metadata_size(s);
if (off != size_from_object(s))
/* Beginning of the filler is the free pointer */
print_section(KERN_ERR, "Padding ", p + off,
size_from_object(s) - off);
dump_stack();
}
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 __printf(3, 4) void slab_err(struct kmem_cache *s, struct page *page,
const 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, u8 val)
{
u8 *p = object;
if (s->flags & SLAB_RED_ZONE)
memset(p - s->red_left_pad, val, s->red_left_pad);
if (s->flags & __OBJECT_POISON) {
memset(p, POISON_FREE, s->object_size - 1);
p[s->object_size - 1] = POISON_END;
}
if (s->flags & SLAB_RED_ZONE)
memset(p + s->object_size, val, s->inuse - s->object_size);
}
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;
u8 *addr = page_address(page);
metadata_access_enable();
fault = memchr_inv(start, value, bytes);
metadata_access_disable();
if (!fault)
return 1;
end = start + bytes;
while (end > fault && end[-1] == value)
end--;
slab_bug(s, "%s overwritten", what);
pr_err("INFO: 0x%p-0x%p @offset=%tu. First byte 0x%x instead of 0x%x\n",
fault, end - 1, fault - addr,
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 at the middle of the object.
*
* Poisoning uses 0x6b (POISON_FREE) and the last byte is
* 0xa5 (POISON_END)
*
* object + s->object_size
* Padding to reach word boundary. This is also used for Redzoning.
* Padding is extended by another word if Redzoning is enabled and
* object_size == 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 object_size 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 = get_info_end(s); /* The end of info */
if (s->flags & SLAB_STORE_USER)
/* We also have user information there */
off += 2 * sizeof(struct track);
off += kasan_metadata_size(s);
if (size_from_object(s) == off)
return 1;
return check_bytes_and_report(s, page, p, "Object padding",
p + off, POISON_INUSE, size_from_object(s) - 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;
u8 *pad;
int length;
int remainder;
if (!(s->flags & SLAB_POISON))
return 1;
start = page_address(page);
length = page_size(page);
end = start + length;
remainder = length % s->size;
if (!remainder)
return 1;
pad = end - remainder;
metadata_access_enable();
fault = memchr_inv(pad, POISON_INUSE, remainder);
metadata_access_disable();
if (!fault)
return 1;
while (end > fault && end[-1] == POISON_INUSE)
end--;
slab_err(s, page, "Padding overwritten. 0x%p-0x%p @offset=%tu",
fault, end - 1, fault - start);
print_section(KERN_ERR, "Padding ", pad, remainder);
restore_bytes(s, "slab padding", POISON_INUSE, fault, end);
return 0;
}
static int check_object(struct kmem_cache *s, struct page *page,
void *object, u8 val)
{
u8 *p = object;
u8 *endobject = object + s->object_size;
if (s->flags & SLAB_RED_ZONE) {
if (!check_bytes_and_report(s, page, object, "Redzone",
object - s->red_left_pad, val, s->red_left_pad))
return 0;
if (!check_bytes_and_report(s, page, object, "Redzone",
endobject, val, s->inuse - s->object_size))
return 0;
} else {
if ((s->flags & SLAB_POISON) && s->object_size < s->inuse) {
check_bytes_and_report(s, page, p, "Alignment padding",
endobject, POISON_INUSE,
s->inuse - s->object_size);
}
}
if (s->flags & SLAB_POISON) {
if (val != SLUB_RED_ACTIVE && (s->flags & __OBJECT_POISON) &&
(!check_bytes_and_report(s, page, p, "Poison", p,
POISON_FREE, s->object_size - 1) ||
!check_bytes_and_report(s, page, p, "Poison",
p + s->object_size - 1, POISON_END, 1)))
return 0;
/*
* check_pad_bytes cleans up on its own.
*/
check_pad_bytes(s, page, p);
}
if (!freeptr_outside_object(s) && val == SLUB_RED_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 lose 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 = order_objects(compound_order(page), s->size);
if (page->objects > maxobj) {
slab_err(s, page, "objects %u > max %u",
page->objects, maxobj);
return 0;
}
if (page->inuse > page->objects) {
slab_err(s, page, "inuse %u > max %u",
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;
void *object = NULL;
int max_objects;
fp = page->freelist;
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);
} 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 = order_objects(compound_order(page), s->size);
if (max_objects > MAX_OBJS_PER_PAGE)
max_objects = MAX_OBJS_PER_PAGE;
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) {
pr_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(KERN_INFO, "Object ", (void *)object,
s->object_size);
dump_stack();
}
}
/*
* Tracking of fully allocated slabs for debugging purposes.
*/
static void add_full(struct kmem_cache *s,
struct kmem_cache_node *n, struct page *page)
{
if (!(s->flags & SLAB_STORE_USER))
return;
lockdep_assert_held(&n->list_lock);
list_add(&page->slab_list, &n->full);
}
static void remove_full(struct kmem_cache *s, struct kmem_cache_node *n, struct page *page)
{
if (!(s->flags & SLAB_STORE_USER))
return;
lockdep_assert_held(&n->list_lock);
list_del(&page->slab_list);
}
/* 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 unsigned long node_nr_slabs(struct kmem_cache_node *n)
{
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 (likely(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 (!kmem_cache_debug_flags(s, SLAB_STORE_USER|SLAB_RED_ZONE|__OBJECT_POISON))
return;
init_object(s, object, SLUB_RED_INACTIVE);
init_tracking(s, object);
}
static
void setup_page_debug(struct kmem_cache *s, struct page *page, void *addr)
{
if (!kmem_cache_debug_flags(s, SLAB_POISON))
return;
metadata_access_enable();
memset(addr, POISON_INUSE, page_size(page));
metadata_access_disable();
}
static inline int alloc_consistency_checks(struct kmem_cache *s,
struct page *page, void *object)
{
if (!check_slab(s, page))
return 0;
if (!check_valid_pointer(s, page, object)) {
object_err(s, page, object, "Freelist Pointer check fails");
return 0;
}
if (!check_object(s, page, object, SLUB_RED_INACTIVE))
return 0;
return 1;
}
static noinline int alloc_debug_processing(struct kmem_cache *s,
struct page *page,
void *object, unsigned long addr)
{
if (s->flags & SLAB_CONSISTENCY_CHECKS) {
if (!alloc_consistency_checks(s, page, object))
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, SLUB_RED_ACTIVE);
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 inline int free_consistency_checks(struct kmem_cache *s,
struct page *page, void *object, unsigned long addr)
{
if (!check_valid_pointer(s, page, object)) {
slab_err(s, page, "Invalid object pointer 0x%p", object);
return 0;
}
if (on_freelist(s, page, object)) {
object_err(s, page, object, "Object already free");
return 0;
}
if (!check_object(s, page, object, SLUB_RED_ACTIVE))
return 0;
if (unlikely(s != page->slab_cache)) {
if (!PageSlab(page)) {
slab_err(s, page, "Attempt to free object(0x%p) outside of slab",
object);
} else if (!page->slab_cache) {
pr_err("SLUB <none>: no slab for object 0x%p.\n",
object);
dump_stack();
} else
object_err(s, page, object,
"page slab pointer corrupt.");
return 0;
}
return 1;
}
/* Supports checking bulk free of a constructed freelist */
static noinline int free_debug_processing(
struct kmem_cache *s, struct page *page,
void *head, void *tail, int bulk_cnt,
unsigned long addr)
{
struct kmem_cache_node *n = get_node(s, page_to_nid(page));
void *object = head;
int cnt = 0;
unsigned long flags;
int ret = 0;
spin_lock_irqsave(&n->list_lock, flags);
slab_lock(page);
if (s->flags & SLAB_CONSISTENCY_CHECKS) {
if (!check_slab(s, page))
goto out;
}
next_object:
cnt++;
if (s->flags & SLAB_CONSISTENCY_CHECKS) {
if (!free_consistency_checks(s, page, object, addr))
goto out;
}
if (s->flags & SLAB_STORE_USER)
set_track(s, object, TRACK_FREE, addr);
trace(s, page, object, 0);
/* Freepointer not overwritten by init_object(), SLAB_POISON moved it */
init_object(s, object, SLUB_RED_INACTIVE);
/* Reached end of constructed freelist yet? */
if (object != tail) {
object = get_freepointer(s, object);
goto next_object;
}
ret = 1;
out:
if (cnt != bulk_cnt)
slab_err(s, page, "Bulk freelist count(%d) invalid(%d)\n",
bulk_cnt, cnt);
slab_unlock(page);
spin_unlock_irqrestore(&n->list_lock, flags);
if (!ret)
slab_fix(s, "Object at 0x%p not freed", object);
return ret;
}
/*
* Parse a block of slub_debug options. Blocks are delimited by ';'
*
* @str: start of block
* @flags: returns parsed flags, or DEBUG_DEFAULT_FLAGS if none specified
* @slabs: return start of list of slabs, or NULL when there's no list
* @init: assume this is initial parsing and not per-kmem-create parsing
*
* returns the start of next block if there's any, or NULL
*/
static char *
parse_slub_debug_flags(char *str, slab_flags_t *flags, char **slabs, bool init)
{
bool higher_order_disable = false;
/* Skip any completely empty blocks */
while (*str && *str == ';')
str++;
if (*str == ',') {
/*
* No options but restriction on slabs. This means full
* debugging for slabs matching a pattern.
*/
*flags = DEBUG_DEFAULT_FLAGS;
goto check_slabs;
}
*flags = 0;
/* Determine which debug features should be switched on */
for (; *str && *str != ',' && *str != ';'; str++) {
switch (tolower(*str)) {
case '-':
*flags = 0;
break;
case 'f':
*flags |= SLAB_CONSISTENCY_CHECKS;
break;
case 'z':
*flags |= SLAB_RED_ZONE;
break;
case 'p':
*flags |= SLAB_POISON;
break;
case 'u':
*flags |= SLAB_STORE_USER;
break;
case 't':
*flags |= SLAB_TRACE;
break;
case 'a':
*flags |= SLAB_FAILSLAB;
break;
case 'o':
/*
* Avoid enabling debugging on caches if its minimum
* order would increase as a result.
*/
higher_order_disable = true;
break;
default:
if (init)
pr_err("slub_debug option '%c' unknown. skipped\n", *str);
}
}
check_slabs:
if (*str == ',')
*slabs = ++str;
else
*slabs = NULL;
/* Skip over the slab list */
while (*str && *str != ';')
str++;
/* Skip any completely empty blocks */
while (*str && *str == ';')
str++;
if (init && higher_order_disable)
disable_higher_order_debug = 1;
if (*str)
return str;
else
return NULL;
}
static int __init setup_slub_debug(char *str)
{
slab_flags_t flags;
char *saved_str;
char *slab_list;
bool global_slub_debug_changed = false;
bool slab_list_specified = false;
slub_debug = DEBUG_DEFAULT_FLAGS;
if (*str++ != '=' || !*str)
/*
* No options specified. Switch on full debugging.
*/
goto out;
saved_str = str;
while (str) {
str = parse_slub_debug_flags(str, &flags, &slab_list, true);
if (!slab_list) {
slub_debug = flags;
global_slub_debug_changed = true;
} else {
slab_list_specified = true;
}
}
/*
* For backwards compatibility, a single list of flags with list of
* slabs means debugging is only enabled for those slabs, so the global
* slub_debug should be 0. We can extended that to multiple lists as
* long as there is no option specifying flags without a slab list.
*/
if (slab_list_specified) {
if (!global_slub_debug_changed)
slub_debug = 0;
slub_debug_string = saved_str;
}
out:
if (slub_debug != 0 || slub_debug_string)
static_branch_enable(&slub_debug_enabled);
if ((static_branch_unlikely(&init_on_alloc) ||
static_branch_unlikely(&init_on_free)) &&
(slub_debug & SLAB_POISON))
pr_info("mem auto-init: SLAB_POISON will take precedence over init_on_alloc/init_on_free\n");
return 1;
}
__setup("slub_debug", setup_slub_debug);
/*
* kmem_cache_flags - apply debugging options to the cache
* @object_size: the size of an object without meta data
* @flags: flags to set
* @name: name of the cache
* @ctor: constructor function
*
* Debug option(s) are applied to @flags. In addition to the debug
* option(s), if a slab name (or multiple) is specified i.e.
* slub_debug=<Debug-Options>,<slab name1>,<slab name2> ...
* then only the select slabs will receive the debug option(s).
*/
slab_flags_t kmem_cache_flags(unsigned int object_size,
slab_flags_t flags, const char *name,
void (*ctor)(void *))
{
char *iter;
size_t len;
char *next_block;
slab_flags_t block_flags;
len = strlen(name);
next_block = slub_debug_string;
/* Go through all blocks of debug options, see if any matches our slab's name */
while (next_block) {
next_block = parse_slub_debug_flags(next_block, &block_flags, &iter, false);
if (!iter)
continue;
/* Found a block that has a slab list, search it */
while (*iter) {
char *end, *glob;
size_t cmplen;
end = strchrnul(iter, ',');
if (next_block && next_block < end)
end = next_block - 1;
glob = strnchr(iter, end - iter, '*');
if (glob)
cmplen = glob - iter;
else
cmplen = max_t(size_t, len, (end - iter));
if (!strncmp(name, iter, cmplen)) {
flags |= block_flags;
return flags;
}
if (!*end || *end == ';')
break;
iter = end + 1;
}
}
return flags | slub_debug;
}
#else /* !CONFIG_SLUB_DEBUG */
static inline void setup_object_debug(struct kmem_cache *s,
struct page *page, void *object) {}
static inline
void setup_page_debug(struct kmem_cache *s, struct page *page, void *addr) {}
static inline int alloc_debug_processing(struct kmem_cache *s,
struct page *page, void *object, unsigned long addr) { return 0; }
static inline int free_debug_processing(
struct kmem_cache *s, struct page *page,
void *head, void *tail, int bulk_cnt,
unsigned long 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, u8 val) { return 1; }
static inline void add_full(struct kmem_cache *s, struct kmem_cache_node *n,
struct page *page) {}
static inline void remove_full(struct kmem_cache *s, struct kmem_cache_node *n,
struct page *page) {}
slab_flags_t kmem_cache_flags(unsigned int object_size,
slab_flags_t flags, const char *name,
void (*ctor)(void *))
{
return flags;
}
#define slub_debug 0
#define disable_higher_order_debug 0
static inline unsigned long slabs_node(struct kmem_cache *s, int node)
{ return 0; }
static inline unsigned long node_nr_slabs(struct kmem_cache_node *n)
{ 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) {}
static bool freelist_corrupted(struct kmem_cache *s, struct page *page,
void **freelist, void *nextfree)
{
return false;
}
#endif /* CONFIG_SLUB_DEBUG */
/*
* Hooks for other subsystems that check memory allocations. In a typical
* production configuration these hooks all should produce no code at all.
*/
static inline void *kmalloc_large_node_hook(void *ptr, size_t size, gfp_t flags)
{
ptr = kasan_kmalloc_large(ptr, size, flags);
/* As ptr might get tagged, call kmemleak hook after KASAN. */
kmemleak_alloc(ptr, size, 1, flags);
return ptr;
}
static __always_inline void kfree_hook(void *x)
{
kmemleak_free(x);
kasan_kfree_large(x, _RET_IP_);
}
static __always_inline bool slab_free_hook(struct kmem_cache *s, void *x)
{
kmemleak_free_recursive(x, s->flags);
/*
* Trouble is that we may no longer disable interrupts in the fast path
* So in order to make the debug calls that expect irqs to be
* disabled we need to disable interrupts temporarily.
*/
#ifdef CONFIG_LOCKDEP
{
unsigned long flags;
local_irq_save(flags);
debug_check_no_locks_freed(x, s->object_size);
local_irq_restore(flags);
}
#endif
if (!(s->flags & SLAB_DEBUG_OBJECTS))
debug_check_no_obj_freed(x, s->object_size);
/* Use KCSAN to help debug racy use-after-free. */
if (!(s->flags & SLAB_TYPESAFE_BY_RCU))
__kcsan_check_access(x, s->object_size,
KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ASSERT);
/* KASAN might put x into memory quarantine, delaying its reuse */
return kasan_slab_free(s, x, _RET_IP_);
}
static inline bool slab_free_freelist_hook(struct kmem_cache *s,
void **head, void **tail)
{
void *object;
void *next = *head;
void *old_tail = *tail ? *tail : *head;
int rsize;
/* Head and tail of the reconstructed freelist */
*head = NULL;
*tail = NULL;
do {
object = next;
next = get_freepointer(s, object);
if (slab_want_init_on_free(s)) {
/*
* Clear the object and the metadata, but don't touch
* the redzone.
*/
memset(object, 0, s->object_size);
rsize = (s->flags & SLAB_RED_ZONE) ? s->red_left_pad
: 0;
memset((char *)object + s->inuse, 0,
s->size - s->inuse - rsize);
}
/* If object's reuse doesn't have to be delayed */
if (!slab_free_hook(s, object)) {
/* Move object to the new freelist */
set_freepointer(s, object, *head);
*head = object;
if (!*tail)
*tail = object;
}
} while (object != old_tail);
if (*head == *tail)
*tail = NULL;
return *head != NULL;
}
static void *setup_object(struct kmem_cache *s, struct page *page,
void *object)
{
setup_object_debug(s, page, object);
object = kasan_init_slab_obj(s, object);
if (unlikely(s->ctor)) {
kasan_unpoison_object_data(s, object);
s->ctor(object);
kasan_poison_object_data(s, object);
}
return object;
}
/*
* Slab allocation and freeing
*/
static inline struct page *alloc_slab_page(struct kmem_cache *s,
gfp_t flags, int node, struct kmem_cache_order_objects oo)
{
struct page *page;
unsigned int order = oo_order(oo);
if (node == NUMA_NO_NODE)
page = alloc_pages(flags, order);
else
page = __alloc_pages_node(node, flags, order);
if (page)
account_slab_page(page, order, s);
return page;
}
#ifdef CONFIG_SLAB_FREELIST_RANDOM
/* Pre-initialize the random sequence cache */
static int init_cache_random_seq(struct kmem_cache *s)
{
unsigned int count = oo_objects(s->oo);
int err;
/* Bailout if already initialised */
if (s->random_seq)
return 0;
err = cache_random_seq_create(s, count, GFP_KERNEL);
if (err) {
pr_err("SLUB: Unable to initialize free list for %s\n",
s->name);
return err;
}
/* Transform to an offset on the set of pages */
if (s->random_seq) {
unsigned int i;
for (i = 0; i < count; i++)
s->random_seq[i] *= s->size;
}
return 0;
}
/* Initialize each random sequence freelist per cache */
static void __init init_freelist_randomization(void)
{
struct kmem_cache *s;
mutex_lock(&slab_mutex);
list_for_each_entry(s, &slab_caches, list)
init_cache_random_seq(s);
mutex_unlock(&slab_mutex);
}
/* Get the next entry on the pre-computed freelist randomized */
static void *next_freelist_entry(struct kmem_cache *s, struct page *page,
unsigned long *pos, void *start,
unsigned long page_limit,
unsigned long freelist_count)
{
unsigned int idx;
/*
* If the target page allocation failed, the number of objects on the
* page might be smaller than the usual size defined by the cache.
*/
do {
idx = s->random_seq[*pos];
*pos += 1;
if (*pos >= freelist_count)
*pos = 0;
} while (unlikely(idx >= page_limit));
return (char *)start + idx;
}
/* Shuffle the single linked freelist based on a random pre-computed sequence */
static bool shuffle_freelist(struct kmem_cache *s, struct page *page)
{
void *start;
void *cur;
void *next;
unsigned long idx, pos, page_limit, freelist_count;
if (page->objects < 2 || !s->random_seq)
return false;
freelist_count = oo_objects(s->oo);
pos = get_random_int() % freelist_count;
page_limit = page->objects * s->size;
start = fixup_red_left(s, page_address(page));
/* First entry is used as the base of the freelist */
cur = next_freelist_entry(s, page, &pos, start, page_limit,
freelist_count);
cur = setup_object(s, page, cur);
page->freelist = cur;
for (idx = 1; idx < page->objects; idx++) {
next = next_freelist_entry(s, page, &pos, start, page_limit,
freelist_count);
next = setup_object(s, page, next);
set_freepointer(s, cur, next);
cur = next;
}
set_freepointer(s, cur, NULL);
return true;
}
#else
static inline int init_cache_random_seq(struct kmem_cache *s)
{
return 0;
}
static inline void init_freelist_randomization(void) { }
static inline bool shuffle_freelist(struct kmem_cache *s, struct page *page)
{
return false;
}
#endif /* CONFIG_SLAB_FREELIST_RANDOM */
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;
gfp_t alloc_gfp;
void *start, *p, *next;
int idx;
bool shuffle;
flags &= gfp_allowed_mask;
if (gfpflags_allow_blocking(flags))
local_irq_enable();
flags |= s->allocflags;
/*
* Let the initial higher-order allocation fail under memory pressure
* so we fall-back to the minimum order allocation.
*/
alloc_gfp = (flags | __GFP_NOWARN | __GFP_NORETRY) & ~__GFP_NOFAIL;
if ((alloc_gfp & __GFP_DIRECT_RECLAIM) && oo_order(oo) > oo_order(s->min))
alloc_gfp = (alloc_gfp | __GFP_NOMEMALLOC) & ~(__GFP_RECLAIM|__GFP_NOFAIL);
page = alloc_slab_page(s, alloc_gfp, node, oo);
if (unlikely(!page)) {
oo = s->min;
alloc_gfp = flags;
/*
* Allocation may have failed due to fragmentation.
* Try a lower order alloc if possible
*/
page = alloc_slab_page(s, alloc_gfp, node, oo);
if (unlikely(!page))
goto out;
stat(s, ORDER_FALLBACK);
}
page->objects = oo_objects(oo);
page->slab_cache = s;
__SetPageSlab(page);
if (page_is_pfmemalloc(page))
SetPageSlabPfmemalloc(page);
kasan_poison_slab(page);
start = page_address(page);
setup_page_debug(s, page, start);
shuffle = shuffle_freelist(s, page);
if (!shuffle) {
start = fixup_red_left(s, start);
start = setup_object(s, page, start);
page->freelist = start;
for (idx = 0, p = start; idx < page->objects - 1; idx++) {
next = p + s->size;
next = setup_object(s, page, next);
set_freepointer(s, p, next);
p = next;
}
set_freepointer(s, p, NULL);
}
page->inuse = page->objects;
page->frozen = 1;
out:
if (gfpflags_allow_blocking(flags))
local_irq_disable();
if (!page)
return NULL;
inc_slabs_node(s, page_to_nid(page), page->objects);
return page;
}
static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
{
if (unlikely(flags & GFP_SLAB_BUG_MASK))
flags = kmalloc_fix_flags(flags);
return allocate_slab(s,
flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
}
static void __free_slab(struct kmem_cache *s, struct page *page)
{
int order = compound_order(page);
int pages = 1 << order;
if (kmem_cache_debug_flags(s, SLAB_CONSISTENCY_CHECKS)) {
void *p;
slab_pad_check(s, page);
for_each_object(p, s, page_address(page),
page->objects)
check_object(s, page, p, SLUB_RED_INACTIVE);
}
__ClearPageSlabPfmemalloc(page);
__ClearPageSlab(page);
page->mapping = NULL;
if (current->reclaim_state)
current->reclaim_state->reclaimed_slab += pages;
unaccount_slab_page(page, order, s);
__free_pages(page, order);
}
static void rcu_free_slab(struct rcu_head *h)
{
struct page *page = container_of(h, struct page, rcu_head);
__free_slab(page->slab_cache, page);
}
static void free_slab(struct kmem_cache *s, struct page *page)
{
if (unlikely(s->flags & SLAB_TYPESAFE_BY_RCU)) {
call_rcu(&page->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);
}
/*
* Management of partially allocated slabs.
*/
static inline void
__add_partial(struct kmem_cache_node *n, struct page *page, int tail)
{
n->nr_partial++;
if (tail == DEACTIVATE_TO_TAIL)
list_add_tail(&page->slab_list, &n->partial);
else
list_add(&page->slab_list, &n->partial);
}
static inline void add_partial(struct kmem_cache_node *n,
struct page *page, int tail)
{
lockdep_assert_held(&n->list_lock);
__add_partial(n, page, tail);
}
static inline void remove_partial(struct kmem_cache_node *n,
struct page *page)
{
lockdep_assert_held(&n->list_lock);
list_del(&page->slab_list);
n->nr_partial--;
}
/*
* Remove slab from the partial list, freeze it and
* return the pointer to the freelist.
*
* Returns a list of objects or NULL if it fails.
*/
static inline void *acquire_slab(struct kmem_cache *s,
struct kmem_cache_node *n, struct page *page,
int mode, int *objects)
{
void *freelist;
unsigned long counters;
struct page new;
lockdep_assert_held(&n->list_lock);
/*
* Zap the freelist and set the frozen bit.
* The old freelist is the list of objects for the
* per cpu allocation list.
*/
freelist = page->freelist;
counters = page->counters;
new.counters = counters;
*objects = new.objects - new.inuse;
if (mode) {
new.inuse = page->objects;
new.freelist = NULL;
} else {
new.freelist = freelist;
}
VM_BUG_ON(new.frozen);
new.frozen = 1;
if (!__cmpxchg_double_slab(s, page,
freelist, counters,
new.freelist, new.counters,
"acquire_slab"))
return NULL;
remove_partial(n, page);
WARN_ON(!freelist);
return freelist;
}
static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain);
static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags);
/*
* Try to allocate a partial slab from a specific node.
*/
static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n,
struct kmem_cache_cpu *c, gfp_t flags)
{
struct page *page, *page2;
void *object = NULL;
unsigned int available = 0;
int objects;
/*
* 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_safe(page, page2, &n->partial, slab_list) {
void *t;
if (!pfmemalloc_match(page, flags))
continue;
t = acquire_slab(s, n, page, object == NULL, &objects);
if (!t)
break;
available += objects;
if (!object) {
c->page = page;
stat(s, ALLOC_FROM_PARTIAL);
object = t;
} else {
put_cpu_partial(s, page, 0);
stat(s, CPU_PARTIAL_NODE);
}
if (!kmem_cache_has_cpu_partial(s)
|| available > slub_cpu_partial(s) / 2)
break;
}
spin_unlock(&n->list_lock);
return object;
}
/*
* Get a page from somewhere. Search in increasing NUMA distances.
*/
static void *get_any_partial(struct kmem_cache *s, gfp_t flags,
struct kmem_cache_cpu *c)
{
#ifdef CONFIG_NUMA
struct zonelist *zonelist;
struct zoneref *z;
struct zone *zone;
enum zone_type highest_zoneidx = gfp_zone(flags);
void *object;
unsigned int cpuset_mems_cookie;
/*
* 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/remote_node_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;
do {
cpuset_mems_cookie = read_mems_allowed_begin();
zonelist = node_zonelist(mempolicy_slab_node(), flags);
for_each_zone_zonelist(zone, z, zonelist, highest_zoneidx) {
struct kmem_cache_node *n;
n = get_node(s, zone_to_nid(zone));
if (n && cpuset_zone_allowed(zone, flags) &&
n->nr_partial > s->min_partial) {
object = get_partial_node(s, n, c, flags);
if (object) {
/*
* Don't check read_mems_allowed_retry()
* here - if mems_allowed was updated in
* parallel, that was a harmless race
* between allocation and the cpuset
* update
*/
return object;
}
}
}
} while (read_mems_allowed_retry(cpuset_mems_cookie));
#endif /* CONFIG_NUMA */
return NULL;
}
/*
* Get a partial page, lock it and return it.
*/
static void *get_partial(struct kmem_cache *s, gfp_t flags, int node,
struct kmem_cache_cpu *c)
{
void *object;
int searchnode = node;
if (node == NUMA_NO_NODE)
searchnode = numa_mem_id();
object = get_partial_node(s, get_node(s, searchnode), c, flags);
if (object || node != NUMA_NO_NODE)
return object;
return get_any_partial(s, flags, c);
}
#ifdef CONFIG_PREEMPTION
/*
* Calculate the next globally unique transaction for disambiguation
* during cmpxchg. The transactions start with the cpu number and are then
* incremented by CONFIG_NR_CPUS.
*/
#define TID_STEP roundup_pow_of_two(CONFIG_NR_CPUS)
#else
/*
* No preemption supported therefore also no need to check for
* different cpus.
*/
#define TID_STEP 1
#endif
static inline unsigned long next_tid(unsigned long tid)
{
return tid + TID_STEP;
}
#ifdef SLUB_DEBUG_CMPXCHG
static inline unsigned int tid_to_cpu(unsigned long tid)
{
return tid % TID_STEP;
}
static inline unsigned long tid_to_event(unsigned long tid)
{
return tid / TID_STEP;
}
#endif
static inline unsigned int init_tid(int cpu)
{
return cpu;
}
static inline void note_cmpxchg_failure(const char *n,
const struct kmem_cache *s, unsigned long tid)
{
#ifdef SLUB_DEBUG_CMPXCHG
unsigned long actual_tid = __this_cpu_read(s->cpu_slab->tid);
pr_info("%s %s: cmpxchg redo ", n, s->name);
#ifdef CONFIG_PREEMPTION
if (tid_to_cpu(tid) != tid_to_cpu(actual_tid))
pr_warn("due to cpu change %d -> %d\n",
tid_to_cpu(tid), tid_to_cpu(actual_tid));
else
#endif
if (tid_to_event(tid) != tid_to_event(actual_tid))
pr_warn("due to cpu running other code. Event %ld->%ld\n",
tid_to_event(tid), tid_to_event(actual_tid));
else
pr_warn("for unknown reason: actual=%lx was=%lx target=%lx\n",
actual_tid, tid, next_tid(tid));
#endif
stat(s, CMPXCHG_DOUBLE_CPU_FAIL);
}
static void init_kmem_cache_cpus(struct kmem_cache *s)
{
int cpu;
for_each_possible_cpu(cpu)
per_cpu_ptr(s->cpu_slab, cpu)->tid = init_tid(cpu);
}
/*
* Remove the cpu slab
*/
static void deactivate_slab(struct kmem_cache *s, struct page *page,
void *freelist, struct kmem_cache_cpu *c)
{
enum slab_modes { M_NONE, M_PARTIAL, M_FULL, M_FREE };
struct kmem_cache_node *n = get_node(s, page_to_nid(page));
int lock = 0;
enum slab_modes l = M_NONE, m = M_NONE;
void *nextfree;
int tail = DEACTIVATE_TO_HEAD;
struct page new;
struct page old;
if (page->freelist) {
stat(s, DEACTIVATE_REMOTE_FREES);
tail = DEACTIVATE_TO_TAIL;
}
/*
* Stage one: Free all available per cpu objects back
* to the page freelist while it is still frozen. Leave the
* last one.
*
* There is no need to take the list->lock because the page
* is still frozen.
*/
while (freelist && (nextfree = get_freepointer(s, freelist))) {
void *prior;
unsigned long counters;
/*
* If 'nextfree' is invalid, it is possible that the object at
* 'freelist' is already corrupted. So isolate all objects
* starting at 'freelist'.
*/
if (freelist_corrupted(s, page, &freelist, nextfree))
break;
do {
prior = page->freelist;
counters = page->counters;
set_freepointer(s, freelist, prior);
new.counters = counters;
new.inuse--;
VM_BUG_ON(!new.frozen);
} while (!__cmpxchg_double_slab(s, page,
prior, counters,
freelist, new.counters,
"drain percpu freelist"));
freelist = nextfree;
}
/*
* Stage two: Ensure that the page is unfrozen while the
* list presence reflects the actual number of objects
* during unfreeze.
*
* We setup the list membership and then perform a cmpxchg
* with the count. If there is a mismatch then the page
* is not unfrozen but the page is on the wrong list.
*
* Then we restart the process which may have to remove
* the page from the list that we just put it on again
* because the number of objects in the slab may have
* changed.
*/
redo:
old.freelist = page->freelist;
old.counters = page->counters;
VM_BUG_ON(!old.frozen);
/* Determine target state of the slab */
new.counters = old.counters;
if (freelist) {
new.inuse--;
set_freepointer(s, freelist, old.freelist);
new.freelist = freelist;
} else
new.freelist = old.freelist;
new.frozen = 0;
if (!new.inuse && n->nr_partial >= s->min_partial)
m = M_FREE;
else if (new.freelist) {
m = M_PARTIAL;
if (!lock) {
lock = 1;
/*
* Taking the spinlock removes the possibility
* that acquire_slab() will see a slab page that
* is frozen
*/
spin_lock(&n->list_lock);
}
} else {
m = M_FULL;
#ifdef CONFIG_SLUB_DEBUG
if ((s->flags & SLAB_STORE_USER) && !lock) {
lock = 1;
/*
* This also ensures that the scanning of full
* slabs from diagnostic functions will not see
* any frozen slabs.
*/
spin_lock(&n->list_lock);
}
#endif
}
if (l != m) {
if (l == M_PARTIAL)
remove_partial(n, page);
else if (l == M_FULL)
remove_full(s, n, page);
if (m == M_PARTIAL)
add_partial(n, page, tail);
else if (m == M_FULL)
add_full(s, n, page);
}
l = m;
if (!__cmpxchg_double_slab(s, page,
old.freelist, old.counters,
new.freelist, new.counters,
"unfreezing slab"))
goto redo;
if (lock)
spin_unlock(&n->list_lock);
if (m == M_PARTIAL)
stat(s, tail);
else if (m == M_FULL)
stat(s, DEACTIVATE_FULL);
else if (m == M_FREE) {
stat(s, DEACTIVATE_EMPTY);
discard_slab(s, page);
stat(s, FREE_SLAB);
}
c->page = NULL;
c->freelist = NULL;
}
/*
* Unfreeze all the cpu partial slabs.
*
* This function must be called with interrupts disabled
* for the cpu using c (or some other guarantee must be there
* to guarantee no concurrent accesses).
*/
static void unfreeze_partials(struct kmem_cache *s,
struct kmem_cache_cpu *c)
{
#ifdef CONFIG_SLUB_CPU_PARTIAL
struct kmem_cache_node *n = NULL, *n2 = NULL;
struct page *page, *discard_page = NULL;
while ((page = slub_percpu_partial(c))) {
struct page new;
struct page old;
slub_set_percpu_partial(c, page);
n2 = get_node(s, page_to_nid(page));
if (n != n2) {
if (n)
spin_unlock(&n->list_lock);
n = n2;
spin_lock(&n->list_lock);
}
do {
old.freelist = page->freelist;
old.counters = page->counters;
VM_BUG_ON(!old.frozen);
new.counters = old.counters;
new.freelist = old.freelist;
new.frozen = 0;
} while (!__cmpxchg_double_slab(s, page,
old.freelist, old.counters,
new.freelist, new.counters,
"unfreezing slab"));
if (unlikely(!new.inuse && n->nr_partial >= s->min_partial)) {
page->next = discard_page;
discard_page = page;
} else {
add_partial(n, page, DEACTIVATE_TO_TAIL);
stat(s, FREE_ADD_PARTIAL);
}
}
if (n)
spin_unlock(&n->list_lock);
while (discard_page) {
page = discard_page;
discard_page = discard_page->next;
stat(s, DEACTIVATE_EMPTY);
discard_slab(s, page);
stat(s, FREE_SLAB);
}
#endif /* CONFIG_SLUB_CPU_PARTIAL */
}
/*
* Put a page that was just frozen (in __slab_free|get_partial_node) into a
* partial page slot if available.
*
* If we did not find a slot then simply move all the partials to the
* per node partial list.
*/
static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain)
{
#ifdef CONFIG_SLUB_CPU_PARTIAL
struct page *oldpage;
int pages;
int pobjects;
preempt_disable();
do {
pages = 0;
pobjects = 0;
oldpage = this_cpu_read(s->cpu_slab->partial);
if (oldpage) {
pobjects = oldpage->pobjects;
pages = oldpage->pages;
if (drain && pobjects > slub_cpu_partial(s)) {
unsigned long flags;
/*
* partial array is full. Move the existing
* set to the per node partial list.
*/
local_irq_save(flags);
unfreeze_partials(s, this_cpu_ptr(s->cpu_slab));
local_irq_restore(flags);
oldpage = NULL;
pobjects = 0;
pages = 0;
stat(s, CPU_PARTIAL_DRAIN);
}
}
pages++;
pobjects += page->objects - page->inuse;
page->pages = pages;
page->pobjects = pobjects;
page->next = oldpage;
} while (this_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page)
!= oldpage);
if (unlikely(!slub_cpu_partial(s))) {
unsigned long flags;
local_irq_save(flags);
unfreeze_partials(s, this_cpu_ptr(s->cpu_slab));
local_irq_restore(flags);
}
preempt_enable();
#endif /* CONFIG_SLUB_CPU_PARTIAL */
}
static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
{
stat(s, CPUSLAB_FLUSH);
deactivate_slab(s, c->page, c->freelist, c);
c->tid = next_tid(c->tid);
}
/*
* 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 = per_cpu_ptr(s->cpu_slab, cpu);
if (c->page)
flush_slab(s, c);
unfreeze_partials(s, c);
}
static void flush_cpu_slab(void *d)
{
struct kmem_cache *s = d;
__flush_cpu_slab(s, smp_processor_id());
}
static bool has_cpu_slab(int cpu, void *info)
{
struct kmem_cache *s = info;
struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
return c->page || slub_percpu_partial(c);
}
static void flush_all(struct kmem_cache *s)
{
on_each_cpu_cond(has_cpu_slab, flush_cpu_slab, s, 1);
}
/*
* Use the cpu notifier to insure that the cpu slabs are flushed when
* necessary.
*/
static int slub_cpu_dead(unsigned int cpu)
{
struct kmem_cache *s;
unsigned long flags;
mutex_lock(&slab_mutex);
list_for_each_entry(s, &slab_caches, list) {
local_irq_save(flags);
__flush_cpu_slab(s, cpu);
local_irq_restore(flags);
}
mutex_unlock(&slab_mutex);
return 0;
}
/*
* Check if the objects in a per cpu structure fit numa
* locality expectations.
*/
static inline int node_match(struct page *page, int node)
{
#ifdef CONFIG_NUMA
if (node != NUMA_NO_NODE && page_to_nid(page) != node)
return 0;
#endif
return 1;
}
#ifdef CONFIG_SLUB_DEBUG
static int count_free(struct page *page)
{
return page->objects - page->inuse;
}
static inline unsigned long node_nr_objs(struct kmem_cache_node *n)
{
return atomic_long_read(&n->total_objects);
}
#endif /* CONFIG_SLUB_DEBUG */
#if defined(CONFIG_SLUB_DEBUG) || defined(CONFIG_SYSFS)
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, slab_list)
x += get_count(page);
spin_unlock_irqrestore(&n->list_lock, flags);
return x;
}
#endif /* CONFIG_SLUB_DEBUG || CONFIG_SYSFS */
static noinline void
slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid)
{
#ifdef CONFIG_SLUB_DEBUG
static DEFINE_RATELIMIT_STATE(slub_oom_rs, DEFAULT_RATELIMIT_INTERVAL,
DEFAULT_RATELIMIT_BURST);
int node;
struct kmem_cache_node *n;
if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slub_oom_rs))
return;
pr_warn("SLUB: Unable to allocate memory on node %d, gfp=%#x(%pGg)\n",
nid, gfpflags, &gfpflags);
pr_warn(" cache: %s, object size: %u, buffer size: %u, default order: %u, min order: %u\n",
s->name, s->object_size, s->size, oo_order(s->oo),
oo_order(s->min));
if (oo_order(s->min) > get_order(s->object_size))
pr_warn(" %s debugging increased min order, use slub_debug=O to disable.\n",
s->name);
for_each_kmem_cache_node(s, node, n) {
unsigned long nr_slabs;
unsigned long nr_objs;
unsigned long nr_free;
nr_free = count_partial(n, count_free);
nr_slabs = node_nr_slabs(n);
nr_objs = node_nr_objs(n);
pr_warn(" node %d: slabs: %ld, objs: %ld, free: %ld\n",
node, nr_slabs, nr_objs, nr_free);
}
#endif
}
static inline void *new_slab_objects(struct kmem_cache *s, gfp_t flags,
int node, struct kmem_cache_cpu **pc)
{
void *freelist;
struct kmem_cache_cpu *c = *pc;
struct page *page;
WARN_ON_ONCE(s->ctor && (flags & __GFP_ZERO));
freelist = get_partial(s, flags, node, c);
if (freelist)
return freelist;
page = new_slab(s, flags, node);
if (page) {
c = raw_cpu_ptr(s->cpu_slab);
if (c->page)
flush_slab(s, c);
/*
* No other reference to the page yet so we can
* muck around with it freely without cmpxchg
*/
freelist = page->freelist;
page->freelist = NULL;
stat(s, ALLOC_SLAB);
c->page = page;
*pc = c;
}
return freelist;
}
static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags)
{
if (unlikely(PageSlabPfmemalloc(page)))
return gfp_pfmemalloc_allowed(gfpflags);
return true;
}
/*
* Check the page->freelist of a page and either transfer the freelist to the
* per cpu freelist or deactivate the page.
*
* The page is still frozen if the return value is not NULL.
*
* If this function returns NULL then the page has been unfrozen.
*
* This function must be called with interrupt disabled.
*/
static inline void *get_freelist(struct kmem_cache *s, struct page *page)
{
struct page new;
unsigned long counters;
void *freelist;
do {
freelist = page->freelist;
counters = page->counters;
new.counters = counters;
VM_BUG_ON(!new.frozen);
new.inuse = page->objects;
new.frozen = freelist != NULL;
} while (!__cmpxchg_double_slab(s, page,
freelist, counters,
NULL, new.counters,
"get_freelist"));
return freelist;
}
/*
* Slow path. The lockless freelist is empty or we need to perform
* debugging duties.
*
* 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.
*
* Version of __slab_alloc to use when we know that interrupts are
* already disabled (which is the case for bulk allocation).
*/
static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
unsigned long addr, struct kmem_cache_cpu *c)
{
void *freelist;
struct page *page;
stat(s, ALLOC_SLOWPATH);
page = c->page;
if (!page) {
/*
* if the node is not online or has no normal memory, just
* ignore the node constraint
*/
if (unlikely(node != NUMA_NO_NODE &&
!node_state(node, N_NORMAL_MEMORY)))
node = NUMA_NO_NODE;
goto new_slab;
}
redo:
if (unlikely(!node_match(page, node))) {
/*
* same as above but node_match() being false already
* implies node != NUMA_NO_NODE
*/
if (!node_state(node, N_NORMAL_MEMORY)) {
node = NUMA_NO_NODE;
goto redo;
} else {
stat(s, ALLOC_NODE_MISMATCH);
deactivate_slab(s, page, c->freelist, c);
goto new_slab;
}
}
/*
* By rights, we should be searching for a slab page that was
* PFMEMALLOC but right now, we are losing the pfmemalloc
* information when the page leaves the per-cpu allocator
*/
if (unlikely(!pfmemalloc_match(page, gfpflags))) {
deactivate_slab(s, page, c->freelist, c);
goto new_slab;
}
/* must check again c->freelist in case of cpu migration or IRQ */
freelist = c->freelist;
if (freelist)
goto load_freelist;
freelist = get_freelist(s, page);
if (!freelist) {
c->page = NULL;
stat(s, DEACTIVATE_BYPASS);
goto new_slab;
}
stat(s, ALLOC_REFILL);
load_freelist:
/*
* freelist is pointing to the list of objects to be used.
* page is pointing to the page from which the objects are obtained.
* That page must be frozen for per cpu allocations to work.
*/
VM_BUG_ON(!c->page->frozen);
c->freelist = get_freepointer(s, freelist);
c->tid = next_tid(c->tid);
return freelist;
new_slab:
if (slub_percpu_partial(c)) {
page = c->page = slub_percpu_partial(c);
slub_set_percpu_partial(c, page);
stat(s, CPU_PARTIAL_ALLOC);
goto redo;
}
freelist = new_slab_objects(s, gfpflags, node, &c);
if (unlikely(!freelist)) {
slab_out_of_memory(s, gfpflags, node);
return NULL;
}
page = c->page;
if (likely(!kmem_cache_debug(s) && pfmemalloc_match(page, gfpflags)))
goto load_freelist;
/* Only entered in the debug case */
if (kmem_cache_debug(s) &&
!alloc_debug_processing(s, page, freelist, addr))
goto new_slab; /* Slab failed checks. Next slab needed */
deactivate_slab(s, page, get_freepointer(s, freelist), c);
return freelist;
}
/*
* Another one that disabled interrupt and compensates for possible
* cpu changes by refetching the per cpu area pointer.
*/
static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
unsigned long addr, struct kmem_cache_cpu *c)
{
void *p;
unsigned long flags;
local_irq_save(flags);
#ifdef CONFIG_PREEMPTION
/*
* We may have been preempted and rescheduled on a different
* cpu before disabling interrupts. Need to reload cpu area
* pointer.
*/
c = this_cpu_ptr(s->cpu_slab);
#endif
p = ___slab_alloc(s, gfpflags, node, addr, c);
local_irq_restore(flags);
return p;
}
/*
* If the object has been wiped upon free, make sure it's fully initialized by
* zeroing out freelist pointer.
*/
static __always_inline void maybe_wipe_obj_freeptr(struct kmem_cache *s,
void *obj)
{
if (unlikely(slab_want_init_on_free(s)) && obj)
memset((void *)((char *)obj + s->offset), 0, sizeof(void *));
}
/*
* 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_node(struct kmem_cache *s,
gfp_t gfpflags, int node, unsigned long addr)
{
void *object;
struct kmem_cache_cpu *c;
struct page *page;
unsigned long tid;
struct obj_cgroup *objcg = NULL;
s = slab_pre_alloc_hook(s, &objcg, 1, gfpflags);
if (!s)
return NULL;
redo:
/*
* Must read kmem_cache cpu data via this cpu ptr. Preemption is
* enabled. We may switch back and forth between cpus while
* reading from one cpu area. That does not matter as long
* as we end up on the original cpu again when doing the cmpxchg.
*
* We should guarantee that tid and kmem_cache are retrieved on
* the same cpu. It could be different if CONFIG_PREEMPTION so we need
* to check if it is matched or not.
*/
do {
tid = this_cpu_read(s->cpu_slab->tid);
c = raw_cpu_ptr(s->cpu_slab);
} while (IS_ENABLED(CONFIG_PREEMPTION) &&
unlikely(tid != READ_ONCE(c->tid)));
/*
* Irqless object alloc/free algorithm used here depends on sequence
* of fetching cpu_slab's data. tid should be fetched before anything
* on c to guarantee that object and page associated with previous tid
* won't be used with current tid. If we fetch tid first, object and
* page could be one associated with next tid and our alloc/free
* request will be failed. In this case, we will retry. So, no problem.
*/
barrier();
/*
* The transaction ids are globally unique per cpu and per operation on
* a per cpu queue. Thus they can be guarantee that the cmpxchg_double
* occurs on the right processor and that there was no operation on the
* linked list in between.
*/
object = c->freelist;
page = c->page;
if (unlikely(!object || !node_match(page, node))) {
object = __slab_alloc(s, gfpflags, node, addr, c);
} else {
void *next_object = get_freepointer_safe(s, object);
/*
* The cmpxchg will only match if there was no additional
* operation and if we are on the right processor.
*
* The cmpxchg does the following atomically (without lock
* semantics!)
* 1. Relocate first pointer to the current per cpu area.
* 2. Verify that tid and freelist have not been changed
* 3. If they were not changed replace tid and freelist
*
* Since this is without lock semantics the protection is only
* against code executing on this cpu *not* from access by
* other cpus.
*/
if (unlikely(!this_cpu_cmpxchg_double(
s->cpu_slab->freelist, s->cpu_slab->tid,
object, tid,
next_object, next_tid(tid)))) {
note_cmpxchg_failure("slab_alloc", s, tid);
goto redo;
}
prefetch_freepointer(s, next_object);
stat(s, ALLOC_FASTPATH);
}
maybe_wipe_obj_freeptr(s, object);
if (unlikely(slab_want_init_on_alloc(gfpflags, s)) && object)
memset(object, 0, s->object_size);
slab_post_alloc_hook(s, objcg, gfpflags, 1, &object);
return object;
}
static __always_inline void *slab_alloc(struct kmem_cache *s,
gfp_t gfpflags, unsigned long addr)
{
return slab_alloc_node(s, gfpflags, NUMA_NO_NODE, addr);
}
void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags)
{
void *ret = slab_alloc(s, gfpflags, _RET_IP_);
trace_kmem_cache_alloc(_RET_IP_, ret, s->object_size,
s->size, gfpflags);
return ret;
}
EXPORT_SYMBOL(kmem_cache_alloc);
#ifdef CONFIG_TRACING
void *kmem_cache_alloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size)
{
void *ret = slab_alloc(s, gfpflags, _RET_IP_);
trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags);
ret = kasan_kmalloc(s, ret, size, gfpflags);
return ret;
}
EXPORT_SYMBOL(kmem_cache_alloc_trace);
#endif
#ifdef CONFIG_NUMA
void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node)
{
void *ret = slab_alloc_node(s, gfpflags, node, _RET_IP_);
trace_kmem_cache_alloc_node(_RET_IP_, ret,
s->object_size, s->size, gfpflags, node);
return ret;
}
EXPORT_SYMBOL(kmem_cache_alloc_node);
#ifdef CONFIG_TRACING
void *kmem_cache_alloc_node_trace(struct kmem_cache *s,
gfp_t gfpflags,
int node, size_t size)
{
void *ret = slab_alloc_node(s, gfpflags, node, _RET_IP_);
trace_kmalloc_node(_RET_IP_, ret,
size, s->size, gfpflags, node);
ret = kasan_kmalloc(s, ret, size, gfpflags);
return ret;
}
EXPORT_SYMBOL(kmem_cache_alloc_node_trace);
#endif
#endif /* CONFIG_NUMA */
/*
* Slow path 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 *head, void *tail, int cnt,
unsigned long addr)
{
void *prior;
int was_frozen;
struct page new;
unsigned long counters;
struct kmem_cache_node *n = NULL;
unsigned long flags;
stat(s, FREE_SLOWPATH);
if (kmem_cache_debug(s) &&
!free_debug_processing(s, page, head, tail, cnt, addr))
return;
do {
if (unlikely(n)) {
spin_unlock_irqrestore(&n->list_lock, flags);
n = NULL;
}
prior = page->freelist;
counters = page->counters;
set_freepointer(s, tail, prior);
new.counters = counters;
was_frozen = new.frozen;
new.inuse -= cnt;
if ((!new.inuse || !prior) && !was_frozen) {
if (kmem_cache_has_cpu_partial(s) && !prior) {
/*
* Slab was on no list before and will be
* partially empty
* We can defer the list move and instead
* freeze it.
*/
new.frozen = 1;
} else { /* Needs to be taken off a list */
n = get_node(s, page_to_nid(page));
/*
* Speculatively acquire the list_lock.
* If the cmpxchg does not succeed then we may
* drop the list_lock without any processing.
*
* Otherwise the list_lock will synchronize with
* other processors updating the list of slabs.
*/
spin_lock_irqsave(&n->list_lock, flags);
}
}
} while (!cmpxchg_double_slab(s, page,
prior, counters,
head, new.counters,
"__slab_free"));
if (likely(!n)) {
if (likely(was_frozen)) {
/*
* The list lock was not taken therefore no list
* activity can be necessary.
*/
stat(s, FREE_FROZEN);
} else if (new.frozen) {
/*
* If we just froze the page then put it onto the
* per cpu partial list.
*/
put_cpu_partial(s, page, 1);
stat(s, CPU_PARTIAL_FREE);
}
return;
}
if (unlikely(!new.inuse && n->nr_partial >= s->min_partial))
goto slab_empty;
/*
* Objects left in the slab. If it was not on the partial list before
* then add it.
*/
if (!kmem_cache_has_cpu_partial(s) && unlikely(!prior)) {
remove_full(s, n, page);
add_partial(n, page, DEACTIVATE_TO_TAIL);
stat(s, FREE_ADD_PARTIAL);
}
spin_unlock_irqrestore(&n->list_lock, flags);
return;
slab_empty:
if (prior) {
/*
* Slab on the partial list.
*/
remove_partial(n, page);
stat(s, FREE_REMOVE_PARTIAL);
} else {
/* Slab must be on the full list */
remove_full(s, n, page);
}
spin_unlock_irqrestore(&n->list_lock, flags);
stat(s, FREE_SLAB);
discard_slab(s, page);
}
/*
* 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.
*
* Bulk free of a freelist with several objects (all pointing to the
* same page) possible by specifying head and tail ptr, plus objects
* count (cnt). Bulk free indicated by tail pointer being set.
*/
static __always_inline void do_slab_free(struct kmem_cache *s,
struct page *page, void *head, void *tail,
int cnt, unsigned long addr)
{
void *tail_obj = tail ? : head;
struct kmem_cache_cpu *c;
unsigned long tid;
memcg_slab_free_hook(s, &head, 1);
redo:
/*
* Determine the currently cpus per cpu slab.
* The cpu may change afterward. However that does not matter since
* data is retrieved via this pointer. If we are on the same cpu
* during the cmpxchg then the free will succeed.
*/
do {
tid = this_cpu_read(s->cpu_slab->tid);
c = raw_cpu_ptr(s->cpu_slab);
} while (IS_ENABLED(CONFIG_PREEMPTION) &&
unlikely(tid != READ_ONCE(c->tid)));
/* Same with comment on barrier() in slab_alloc_node() */
barrier();
if (likely(page == c->page)) {
void **freelist = READ_ONCE(c->freelist);
set_freepointer(s, tail_obj, freelist);
if (unlikely(!this_cpu_cmpxchg_double(
s->cpu_slab->freelist, s->cpu_slab->tid,
freelist, tid,
head, next_tid(tid)))) {
note_cmpxchg_failure("slab_free", s, tid);
goto redo;
}
stat(s, FREE_FASTPATH);
} else
__slab_free(s, page, head, tail_obj, cnt, addr);
}
static __always_inline void slab_free(struct kmem_cache *s, struct page *page,
void *head, void *tail, int cnt,
unsigned long addr)
{
/*
* With KASAN enabled slab_free_freelist_hook modifies the freelist
* to remove objects, whose reuse must be delayed.
*/
if (slab_free_freelist_hook(s, &head, &tail))
do_slab_free(s, page, head, tail, cnt, addr);
}
#ifdef CONFIG_KASAN_GENERIC
void ___cache_free(struct kmem_cache *cache, void *x, unsigned long addr)
{
do_slab_free(cache, virt_to_head_page(x), x, NULL, 1, addr);
}
#endif
void kmem_cache_free(struct kmem_cache *s, void *x)
{
s = cache_from_obj(s, x);
if (!s)
return;
slab_free(s, virt_to_head_page(x), x, NULL, 1, _RET_IP_);
trace_kmem_cache_free(_RET_IP_, x);
}
EXPORT_SYMBOL(kmem_cache_free);
struct detached_freelist {
struct page *page;
void *tail;
void *freelist;
int cnt;
struct kmem_cache *s;
};
/*
* This function progressively scans the array with free objects (with
* a limited look ahead) and extract objects belonging to the same
* page. It builds a detached freelist directly within the given
* page/objects. This can happen without any need for
* synchronization, because the objects are owned by running process.
* The freelist is build up as a single linked list in the objects.
* The idea is, that this detached freelist can then be bulk
* transferred to the real freelist(s), but only requiring a single
* synchronization primitive. Look ahead in the array is limited due
* to performance reasons.
*/
static inline
int build_detached_freelist(struct kmem_cache *s, size_t size,
void **p, struct detached_freelist *df)
{
size_t first_skipped_index = 0;
int lookahead = 3;
void *object;
struct page *page;
/* Always re-init detached_freelist */
df->page = NULL;
do {
object = p[--size];
/* Do we need !ZERO_OR_NULL_PTR(object) here? (for kfree) */
} while (!object && size);
if (!object)
return 0;
page = virt_to_head_page(object);
if (!s) {
/* Handle kalloc'ed objects */
if (unlikely(!PageSlab(page))) {
BUG_ON(!PageCompound(page));
kfree_hook(object);
__free_pages(page, compound_order(page));
p[size] = NULL; /* mark object processed */
return size;
}
/* Derive kmem_cache from object */
df->s = page->slab_cache;
} else {
df->s = cache_from_obj(s, object); /* Support for memcg */
}
/* Start new detached freelist */
df->page = page;
set_freepointer(df->s, object, NULL);
df->tail = object;
df->freelist = object;
p[size] = NULL; /* mark object processed */
df->cnt = 1;
while (size) {
object = p[--size];
if (!object)
continue; /* Skip processed objects */
/* df->page is always set at this point */
if (df->page == virt_to_head_page(object)) {
/* Opportunity build freelist */
set_freepointer(df->s, object, df->freelist);
df->freelist = object;
df->cnt++;
p[size] = NULL; /* mark object processed */
continue;
}
/* Limit look ahead search */
if (!--lookahead)
break;
if (!first_skipped_index)
first_skipped_index = size + 1;
}
return first_skipped_index;
}
/* Note that interrupts must be enabled when calling this function. */
void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p)
{
if (WARN_ON(!size))
return;
memcg_slab_free_hook(s, p, size);
do {
struct detached_freelist df;
size = build_detached_freelist(s, size, p, &df);
if (!df.page)
continue;
slab_free(df.s, df.page, df.freelist, df.tail, df.cnt,_RET_IP_);
} while (likely(size));
}
EXPORT_SYMBOL(kmem_cache_free_bulk);
/* Note that interrupts must be enabled when calling this function. */
int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
void **p)
{
struct kmem_cache_cpu *c;
int i;
struct obj_cgroup *objcg = NULL;
/* memcg and kmem_cache debug support */
s = slab_pre_alloc_hook(s, &objcg, size, flags);
if (unlikely(!s))
return false;
/*
* Drain objects in the per cpu slab, while disabling local
* IRQs, which protects against PREEMPT and interrupts
* handlers invoking normal fastpath.
*/
local_irq_disable();
c = this_cpu_ptr(s->cpu_slab);
for (i = 0; i < size; i++) {
void *object = c->freelist;
if (unlikely(!object)) {
/*
* We may have removed an object from c->freelist using
* the fastpath in the previous iteration; in that case,
* c->tid has not been bumped yet.
* Since ___slab_alloc() may reenable interrupts while
* allocating memory, we should bump c->tid now.
*/
c->tid = next_tid(c->tid);
/*
* Invoking slow path likely have side-effect
* of re-populating per CPU c->freelist
*/
p[i] = ___slab_alloc(s, flags, NUMA_NO_NODE,
_RET_IP_, c);
if (unlikely(!p[i]))
goto error;
c = this_cpu_ptr(s->cpu_slab);
maybe_wipe_obj_freeptr(s, p[i]);
continue; /* goto for-loop */
}
c->freelist = get_freepointer(s, object);
p[i] = object;
maybe_wipe_obj_freeptr(s, p[i]);
}
c->tid = next_tid(c->tid);
local_irq_enable();
/* Clear memory outside IRQ disabled fastpath loop */
if (unlikely(slab_want_init_on_alloc(flags, s))) {
int j;
for (j = 0; j < i; j++)
memset(p[j], 0, s->object_size);
}
/* memcg and kmem_cache debug support */
slab_post_alloc_hook(s, objcg, flags, size, p);
return i;
error:
local_irq_enable();
slab_post_alloc_hook(s, objcg, flags, i, p);
__kmem_cache_free_bulk(s, i, p);
return 0;
}
EXPORT_SYMBOL(kmem_cache_alloc_bulk);
/*
* 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 unsigned int slub_min_order;
static unsigned int slub_max_order = PAGE_ALLOC_COSTLY_ORDER;
static unsigned int slub_min_objects;
/*
* 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 unsigned int slab_order(unsigned int size,
unsigned int min_objects, unsigned int max_order,
unsigned int fract_leftover)
{
unsigned int min_order = slub_min_order;
unsigned int order;
if (order_objects(min_order, size) > MAX_OBJS_PER_PAGE)
return get_order(size * MAX_OBJS_PER_PAGE) - 1;
for (order = max(min_order, (unsigned int)get_order(min_objects * size));
order <= max_order; order++) {
unsigned int slab_size = (unsigned int)PAGE_SIZE << order;
unsigned int rem;
rem = slab_size % size;
if (rem <= slab_size / fract_leftover)
break;
}
return order;
}
static inline int calculate_order(unsigned int size)
{
unsigned int order;
unsigned int min_objects;
unsigned int max_objects;
/*
* 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 increase 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);
max_objects = order_objects(slub_max_order, size);
min_objects = min(min_objects, max_objects);
while (min_objects > 1) {
unsigned int fraction;
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--;
}
/*
* 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;
}
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);
atomic_long_set(&n->total_objects, 0);
INIT_LIST_HEAD(&n->full);
#endif
}
static inline int alloc_kmem_cache_cpus(struct kmem_cache *s)
{
BUILD_BUG_ON(PERCPU_DYNAMIC_EARLY_SIZE <
KMALLOC_SHIFT_HIGH * sizeof(struct kmem_cache_cpu));
/*
* Must align to double word boundary for the double cmpxchg
* instructions to work; see __pcpu_double_call_return_bool().
*/
s->cpu_slab = __alloc_percpu(sizeof(struct kmem_cache_cpu),
2 * sizeof(void *));
if (!s->cpu_slab)
return 0;
init_kmem_cache_cpus(s);
return 1;
}
static struct kmem_cache *kmem_cache_node;
/*
* 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 kmem_cache_node
* when allocating for the kmem_cache_node. This is used for bootstrapping
* memory on a fresh node that has no slab structures yet.
*/
static void early_kmem_cache_node_alloc(int node)
{
struct page *page;
struct kmem_cache_node *n;
BUG_ON(kmem_cache_node->size < sizeof(struct kmem_cache_node));
page = new_slab(kmem_cache_node, GFP_NOWAIT, node);
BUG_ON(!page);
if (page_to_nid(page) != node) {
pr_err("SLUB: Unable to allocate memory from node %d\n", node);
pr_err("SLUB: Allocating a useless per node structure in order to be able to continue\n");
}
n = page->freelist;
BUG_ON(!n);
#ifdef CONFIG_SLUB_DEBUG
init_object(kmem_cache_node, n, SLUB_RED_ACTIVE);
init_tracking(kmem_cache_node, n);
#endif
n = kasan_kmalloc(kmem_cache_node, n, sizeof(struct kmem_cache_node),
GFP_KERNEL);
page->freelist = get_freepointer(kmem_cache_node, n);
page->inuse = 1;
page->frozen = 0;
kmem_cache_node->node[node] = n;
init_kmem_cache_node(n);
inc_slabs_node(kmem_cache_node, node, page->objects);
/*
* No locks need to be taken here as it has just been
* initialized and there is no concurrent access.
*/
__add_partial(n, page, DEACTIVATE_TO_HEAD);
}
static void free_kmem_cache_nodes(struct kmem_cache *s)
{
int node;
struct kmem_cache_node *n;
for_each_kmem_cache_node(s, node, n) {
s->node[node] = NULL;
kmem_cache_free(kmem_cache_node, n);
}
}
void __kmem_cache_release(struct kmem_cache *s)
{
cache_random_seq_destroy(s);
free_percpu(s->cpu_slab);
free_kmem_cache_nodes(s);
}
static int init_kmem_cache_nodes(struct kmem_cache *s)
{
int node;
for_each_node_state(node, N_NORMAL_MEMORY) {
struct kmem_cache_node *n;
if (slab_state == DOWN) {
early_kmem_cache_node_alloc(node);
continue;
}
n = kmem_cache_alloc_node(kmem_cache_node,
GFP_KERNEL, node);
if (!n) {
free_kmem_cache_nodes(s);
return 0;
}
init_kmem_cache_node(n);
s->node[node] = n;
}
return 1;
}
static void set_min_partial(struct kmem_cache *s, unsigned long min)
{
if (min < MIN_PARTIAL)
min = MIN_PARTIAL;
else if (min > MAX_PARTIAL)
min = MAX_PARTIAL;
s->min_partial = min;
}
static void set_cpu_partial(struct kmem_cache *s)
{
#ifdef CONFIG_SLUB_CPU_PARTIAL
/*
* cpu_partial determined the maximum number of objects kept in the
* per cpu partial lists of a processor.
*
* Per cpu partial lists mainly contain slabs that just have one
* object freed. If they are used for allocation then they can be
* filled up again with minimal effort. The slab will never hit the
* per node partial lists and therefore no locking will be required.
*
* This setting also determines
*
* A) The number of objects from per cpu partial slabs dumped to the
* per node list when we reach the limit.
* B) The number of objects in cpu partial slabs to extract from the
* per node list when we run out of per cpu objects. We only fetch
* 50% to keep some capacity around for frees.
*/
if (!kmem_cache_has_cpu_partial(s))
slub_set_cpu_partial(s, 0);
else if (s->size >= PAGE_SIZE)
slub_set_cpu_partial(s, 2);
else if (s->size >= 1024)
slub_set_cpu_partial(s, 6);
else if (s->size >= 256)
slub_set_cpu_partial(s, 13);
else
slub_set_cpu_partial(s, 30);
#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)
{
slab_flags_t flags = s->flags;
unsigned int size = s->object_size;
unsigned int freepointer_area;
unsigned 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 *));
/*
* This is the area of the object where a freepointer can be
* safely written. If redzoning adds more to the inuse size, we
* can't use that portion for writing the freepointer, so
* s->offset must be limited within this for the general case.
*/
freepointer_area = size;
#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_TYPESAFE_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->object_size)
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_TYPESAFE_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.
*
* The assumption that s->offset >= s->inuse means free
* pointer is outside of the object is used in the
* freeptr_outside_object() function. If that is no
* longer true, the function needs to be modified.
*/
s->offset = size;
size += sizeof(void *);
} else if (freepointer_area > sizeof(void *)) {
/*
* Store freelist pointer near middle of object to keep
* it away from the edges of the object to avoid small
* sized over/underflows from neighboring allocations.
*/
s->offset = ALIGN(freepointer_area / 2, 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);
#endif
kasan_cache_create(s, &size, &s->flags);
#ifdef CONFIG_SLUB_DEBUG
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 a user writes before the start
* of the object.
*/
size += sizeof(void *);
s->red_left_pad = sizeof(void *);
s->red_left_pad = ALIGN(s->red_left_pad, s->align);
size += s->red_left_pad;
}
#endif
/*
* 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, s->align);
s->size = size;
s->reciprocal_size = reciprocal_value(size);
if (forced_order >= 0)
order = forced_order;
else
order = calculate_order(size);
if ((int)order < 0)
return 0;
s->allocflags = 0;
if (order)
s->allocflags |= __GFP_COMP;
if (s->flags & SLAB_CACHE_DMA)
s->allocflags |= GFP_DMA;
if (s->flags & SLAB_CACHE_DMA32)
s->allocflags |= GFP_DMA32;
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, slab_flags_t flags)
{
s->flags = kmem_cache_flags(s->size, flags, s->name, s->ctor);
#ifdef CONFIG_SLAB_FREELIST_HARDENED
s->random = get_random_long();
#endif
if (!calculate_sizes(s, -1))
goto error;
if (disable_higher_order_debug) {
/*
* Disable debugging flags that store metadata if the min slab
* order increased.
*/
if (get_order(s->size) > get_order(s->object_size)) {
s->flags &= ~DEBUG_METADATA_FLAGS;
s->offset = 0;
if (!calculate_sizes(s, -1))
goto error;
}
}
#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
if (system_has_cmpxchg_double() && (s->flags & SLAB_NO_CMPXCHG) == 0)
/* Enable fast mode */
s->flags |= __CMPXCHG_DOUBLE;
#endif
/*
* The larger the object size is, the more pages we want on the partial
* list to avoid pounding the page allocator excessively.
*/
set_min_partial(s, ilog2(s->size) / 2);
set_cpu_partial(s);
#ifdef CONFIG_NUMA
s->remote_node_defrag_ratio = 1000;
#endif
/* Initialize the pre-computed randomized freelist if slab is up */
if (slab_state >= UP) {
if (init_cache_random_seq(s))
goto error;
}
if (!init_kmem_cache_nodes(s))
goto error;
if (alloc_kmem_cache_cpus(s))
return 0;
free_kmem_cache_nodes(s);
error:
return -EINVAL;
}
static void list_slab_objects(struct kmem_cache *s, struct page *page,
const char *text)
{
#ifdef CONFIG_SLUB_DEBUG
void *addr = page_address(page);
unsigned long *map;
void *p;
slab_err(s, page, text, s->name);
slab_lock(page);
map = get_map(s, page);
for_each_object(p, s, addr, page->objects) {
if (!test_bit(__obj_to_index(s, addr, p), map)) {
pr_err("INFO: Object 0x%p @offset=%tu\n", p, p - addr);
print_tracking(s, p);
}
}
put_map(map);
slab_unlock(page);
#endif
}
/*
* Attempt to free all partial slabs on a node.
* This is called from __kmem_cache_shutdown(). We must take list_lock
* because sysfs file might still access partial list after the shutdowning.
*/
static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n)
{
LIST_HEAD(discard);
struct page *page, *h;
BUG_ON(irqs_disabled());
spin_lock_irq(&n->list_lock);
list_for_each_entry_safe(page, h, &n->partial, slab_list) {
if (!page->inuse) {
remove_partial(n, page);
list_add(&page->slab_list, &discard);
} else {
list_slab_objects(s, page,
"Objects remaining in %s on __kmem_cache_shutdown()");
}
}
spin_unlock_irq(&n->list_lock);
list_for_each_entry_safe(page, h, &discard, slab_list)
discard_slab(s, page);
}
bool __kmem_cache_empty(struct kmem_cache *s)
{
int node;
struct kmem_cache_node *n;
for_each_kmem_cache_node(s, node, n)
if (n->nr_partial || slabs_node(s, node))
return false;
return true;
}
/*
* Release all resources used by a slab cache.
*/
int __kmem_cache_shutdown(struct kmem_cache *s)
{
int node;
struct kmem_cache_node *n;
flush_all(s);
/* Attempt to free all objects */
for_each_kmem_cache_node(s, node, n) {
free_partial(s, n);
if (n->nr_partial || slabs_node(s, node))
return 1;
}
return 0;
}
/********************************************************************
* Kmalloc subsystem
*******************************************************************/
static int __init setup_slub_min_order(char *str)
{
get_option(&str, (int *)&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, (int *)&slub_max_order);
slub_max_order = min(slub_max_order, (unsigned int)MAX_ORDER - 1);
return 1;
}
__setup("slub_max_order=", setup_slub_max_order);
static int __init setup_slub_min_objects(char *str)
{
get_option(&str, (int *)&slub_min_objects);
return 1;
}
__setup("slub_min_objects=", setup_slub_min_objects);
void *__kmalloc(size_t size, gfp_t flags)
{
struct kmem_cache *s;
void *ret;
if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
return kmalloc_large(size, flags);
s = kmalloc_slab(size, flags);
if (unlikely(ZERO_OR_NULL_PTR(s)))
return s;
ret = slab_alloc(s, flags, _RET_IP_);
trace_kmalloc(_RET_IP_, ret, size, s->size, flags);
ret = kasan_kmalloc(s, ret, size, flags);
return ret;
}
EXPORT_SYMBOL(__kmalloc);
#ifdef CONFIG_NUMA
static void *kmalloc_large_node(size_t size, gfp_t flags, int node)
{
struct page *page;
void *ptr = NULL;
unsigned int order = get_order(size);
flags |= __GFP_COMP;
page = alloc_pages_node(node, flags, order);
if (page) {
ptr = page_address(page);
mod_node_page_state(page_pgdat(page), NR_SLAB_UNRECLAIMABLE_B,
PAGE_SIZE << order);
}
return kmalloc_large_node_hook(ptr, size, flags);
}
void *__kmalloc_node(size_t size, gfp_t flags, int node)
{
struct kmem_cache *s;
void *ret;
if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
ret = kmalloc_large_node(size, flags, node);
trace_kmalloc_node(_RET_IP_, ret,
size, PAGE_SIZE << get_order(size),
flags, node);
return ret;
}
s = kmalloc_slab(size, flags);
if (unlikely(ZERO_OR_NULL_PTR(s)))
return s;
ret = slab_alloc_node(s, flags, node, _RET_IP_);
trace_kmalloc_node(_RET_IP_, ret, size, s->size, flags, node);
ret = kasan_kmalloc(s, ret, size, flags);
return ret;
}
EXPORT_SYMBOL(__kmalloc_node);
#endif /* CONFIG_NUMA */
#ifdef CONFIG_HARDENED_USERCOPY
/*
* Rejects incorrectly sized objects and objects that are to be copied
* to/from userspace but do not fall entirely within the containing slab
* cache's usercopy region.
*
* Returns NULL if check passes, otherwise const char * to name of cache
* to indicate an error.
*/
void __check_heap_object(const void *ptr, unsigned long n, struct page *page,
bool to_user)
{
struct kmem_cache *s;
unsigned int offset;
size_t object_size;
ptr = kasan_reset_tag(ptr);
/* Find object and usable object size. */
s = page->slab_cache;
/* Reject impossible pointers. */
if (ptr < page_address(page))
usercopy_abort("SLUB object not in SLUB page?!", NULL,
to_user, 0, n);
/* Find offset within object. */
offset = (ptr - page_address(page)) % s->size;
/* Adjust for redzone and reject if within the redzone. */
if (kmem_cache_debug_flags(s, SLAB_RED_ZONE)) {
if (offset < s->red_left_pad)
usercopy_abort("SLUB object in left red zone",
s->name, to_user, offset, n);
offset -= s->red_left_pad;
}
/* Allow address range falling entirely within usercopy region. */
if (offset >= s->useroffset &&
offset - s->useroffset <= s->usersize &&
n <= s->useroffset - offset + s->usersize)
return;
/*
* If the copy is still within the allocated object, produce
* a warning instead of rejecting the copy. This is intended
* to be a temporary method to find any missing usercopy
* whitelists.
*/
object_size = slab_ksize(s);
if (usercopy_fallback &&
offset <= object_size && n <= object_size - offset) {
usercopy_warn("SLUB object", s->name, to_user, offset, n);
return;
}
usercopy_abort("SLUB object", s->name, to_user, offset, n);
}
#endif /* CONFIG_HARDENED_USERCOPY */
size_t __ksize(const void *object)
{
struct page *page;
if (unlikely(object == ZERO_SIZE_PTR))
return 0;
page = virt_to_head_page(object);
if (unlikely(!PageSlab(page))) {
WARN_ON(!PageCompound(page));
return page_size(page);
}
return slab_ksize(page->slab_cache);
}
EXPORT_SYMBOL(__ksize);
void kfree(const void *x)
{
struct page *page;
void *object = (void *)x;
trace_kfree(_RET_IP_, x);
if (unlikely(ZERO_OR_NULL_PTR(x)))
return;
page = virt_to_head_page(x);
if (unlikely(!PageSlab(page))) {
unsigned int order = compound_order(page);
BUG_ON(!PageCompound(page));
kfree_hook(object);
mod_node_page_state(page_pgdat(page), NR_SLAB_UNRECLAIMABLE_B,
-(PAGE_SIZE << order));
__free_pages(page, order);
return;
}
slab_free(page->slab_cache, page, object, NULL, 1, _RET_IP_);
}
EXPORT_SYMBOL(kfree);
#define SHRINK_PROMOTE_MAX 32
/*
* kmem_cache_shrink discards empty slabs and promotes the slabs filled
* up most to the head of the partial lists. 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;
struct list_head discard;
struct list_head promote[SHRINK_PROMOTE_MAX];
unsigned long flags;
int ret = 0;
flush_all(s);
for_each_kmem_cache_node(s, node, n) {
INIT_LIST_HEAD(&discard);
for (i = 0; i < SHRINK_PROMOTE_MAX; i++)
INIT_LIST_HEAD(promote + i);
spin_lock_irqsave(&n->list_lock, flags);
/*
* Build lists of slabs to discard or promote.
*
* 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, slab_list) {
int free = page->objects - page->inuse;
/* Do not reread page->inuse */
barrier();
/* We do not keep full slabs on the list */
BUG_ON(free <= 0);
if (free == page->objects) {
list_move(&page->slab_list, &discard);
n->nr_partial--;
} else if (free <= SHRINK_PROMOTE_MAX)
list_move(&page->slab_list, promote + free - 1);
}
/*
* Promote the slabs filled up most to the head of the
* partial list.
*/
for (i = SHRINK_PROMOTE_MAX - 1; i >= 0; i--)
list_splice(promote + i, &n->partial);
spin_unlock_irqrestore(&n->list_lock, flags);
/* Release empty slabs */
list_for_each_entry_safe(page, t, &discard, slab_list)
discard_slab(s, page);
if (slabs_node(s, node))
ret = 1;
}
return ret;
}
static int slab_mem_going_offline_callback(void *arg)
{
struct kmem_cache *s;
mutex_lock(&slab_mutex);
list_for_each_entry(s, &slab_caches, list)
__kmem_cache_shrink(s);
mutex_unlock(&slab_mutex);
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_normal;
/*
* If the node still has available memory. we need kmem_cache_node
* for it yet.
*/
if (offline_node < 0)
return;
mutex_lock(&slab_mutex);
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 shouldn't call this
* callback. So, we must fail.
*/
BUG_ON(slabs_node(s, offline_node));
s->node[offline_node] = NULL;
kmem_cache_free(kmem_cache_node, n);
}
}
mutex_unlock(&slab_mutex);
}
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_normal;
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 available yet. We must
* allocate a kmem_cache_node structure in order to bring the node
* online.
*/
mutex_lock(&slab_mutex);
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(kmem_cache_node, GFP_KERNEL);
if (!n) {
ret = -ENOMEM;
goto out;
}
init_kmem_cache_node(n);
s->node[nid] = n;
}
out:
mutex_unlock(&slab_mutex);
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;
}
if (ret)
ret = notifier_from_errno(ret);
else
ret = NOTIFY_OK;
return ret;
}
static struct notifier_block slab_memory_callback_nb = {
.notifier_call = slab_memory_callback,
.priority = SLAB_CALLBACK_PRI,
};
/********************************************************************
* Basic setup of slabs
*******************************************************************/
/*
* Used for early kmem_cache structures that were allocated using
* the page allocator. Allocate them properly then fix up the pointers
* that may be pointing to the wrong kmem_cache structure.
*/
static struct kmem_cache * __init bootstrap(struct kmem_cache *static_cache)
{
int node;
struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
struct kmem_cache_node *n;
memcpy(s, static_cache, kmem_cache->object_size);
/*
* This runs very early, and only the boot processor is supposed to be
* up. Even if it weren't true, IRQs are not up so we couldn't fire
* IPIs around.
*/
__flush_cpu_slab(s, smp_processor_id());
for_each_kmem_cache_node(s, node, n) {
struct page *p;
list_for_each_entry(p, &n->partial, slab_list)
p->slab_cache = s;
#ifdef CONFIG_SLUB_DEBUG
list_for_each_entry(p, &n->full, slab_list)
p->slab_cache = s;
#endif
}
list_add(&s->list, &slab_caches);
return s;
}
void __init kmem_cache_init(void)
{
static __initdata struct kmem_cache boot_kmem_cache,
boot_kmem_cache_node;
if (debug_guardpage_minorder())
slub_max_order = 0;
kmem_cache_node = &boot_kmem_cache_node;
kmem_cache = &boot_kmem_cache;
create_boot_cache(kmem_cache_node, "kmem_cache_node",
sizeof(struct kmem_cache_node), SLAB_HWCACHE_ALIGN, 0, 0);
register_hotmemory_notifier(&slab_memory_callback_nb);
/* Able to allocate the per node structures */
slab_state = PARTIAL;
create_boot_cache(kmem_cache, "kmem_cache",
offsetof(struct kmem_cache, node) +
nr_node_ids * sizeof(struct kmem_cache_node *),
SLAB_HWCACHE_ALIGN, 0, 0);
kmem_cache = bootstrap(&boot_kmem_cache);
kmem_cache_node = bootstrap(&boot_kmem_cache_node);
/* Now we can use the kmem_cache to allocate kmalloc slabs */
setup_kmalloc_cache_index_table();
create_kmalloc_caches(0);
/* Setup random freelists for each cache */
init_freelist_randomization();
cpuhp_setup_state_nocalls(CPUHP_SLUB_DEAD, "slub:dead", NULL,
slub_cpu_dead);
pr_info("SLUB: HWalign=%d, Order=%u-%u, MinObjects=%u, CPUs=%u, Nodes=%u\n",
cache_line_size(),
slub_min_order, slub_max_order, slub_min_objects,
nr_cpu_ids, nr_node_ids);
}
void __init kmem_cache_init_late(void)
{
}
struct kmem_cache *
__kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
slab_flags_t flags, void (*ctor)(void *))
{
struct kmem_cache *s;
s = find_mergeable(size, align, flags, name, ctor);
if (s) {
s->refcount++;
/*
* Adjust the object sizes so that we clear
* the complete object on kzalloc.
*/
s->object_size = max(s->object_size, size);
s->inuse = max(s->inuse, ALIGN(size, sizeof(void *)));
if (sysfs_slab_alias(s, name)) {
s->refcount--;
s = NULL;
}
}
return s;
}
int __kmem_cache_create(struct kmem_cache *s, slab_flags_t flags)
{
int err;
err = kmem_cache_open(s, flags);
if (err)
return err;
/* Mutex is not taken during early boot */
if (slab_state <= UP)
return 0;
err = sysfs_slab_add(s);
if (err)
__kmem_cache_release(s);
return err;
}
void *__kmalloc_track_caller(size_t size, gfp_t gfpflags, unsigned long caller)
{
struct kmem_cache *s;
void *ret;
if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
return kmalloc_large(size, gfpflags);
s = kmalloc_slab(size, gfpflags);
if (unlikely(ZERO_OR_NULL_PTR(s)))
return s;
ret = slab_alloc(s, gfpflags, caller);
/* Honor the call site pointer we received. */
trace_kmalloc(caller, ret, size, s->size, gfpflags);
return ret;
}
EXPORT_SYMBOL(__kmalloc_track_caller);
#ifdef CONFIG_NUMA
void *__kmalloc_node_track_caller(size_t size, gfp_t gfpflags,
int node, unsigned long caller)
{
struct kmem_cache *s;
void *ret;
if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
ret = kmalloc_large_node(size, gfpflags, node);
trace_kmalloc_node(caller, ret,
size, PAGE_SIZE << get_order(size),
gfpflags, node);
return ret;
}
s = kmalloc_slab(size, gfpflags);
if (unlikely(ZERO_OR_NULL_PTR(s)))
return s;
ret = slab_alloc_node(s, gfpflags, node, caller);
/* Honor the call site pointer we received. */
trace_kmalloc_node(caller, ret, size, s->size, gfpflags, node);
return ret;
}
EXPORT_SYMBOL(__kmalloc_node_track_caller);
#endif
#ifdef CONFIG_SYSFS
static int count_inuse(struct page *page)
{
return page->inuse;
}
static int count_total(struct page *page)
{
return page->objects;
}
#endif
#ifdef CONFIG_SLUB_DEBUG
static void validate_slab(struct kmem_cache *s, struct page *page)
{
void *p;
void *addr = page_address(page);
unsigned long *map;
slab_lock(page);
if (!check_slab(s, page) || !on_freelist(s, page, NULL))
goto unlock;
/* Now we know that a valid freelist exists */
map = get_map(s, page);
for_each_object(p, s, addr, page->objects) {
u8 val = test_bit(__obj_to_index(s, addr, p), map) ?
SLUB_RED_INACTIVE : SLUB_RED_ACTIVE;
if (!check_object(s, page, p, val))
break;
}
put_map(map);
unlock:
slab_unlock(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, slab_list) {
validate_slab(s, page);
count++;
}
if (count != n->nr_partial)
pr_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, slab_list) {
validate_slab(s, page);
count++;
}
if (count != atomic_long_read(&n->nr_slabs))
pr_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;
struct kmem_cache_node *n;
flush_all(s);
for_each_kmem_cache_node(s, node, n)
count += validate_slab_node(s, n);
return count;
}
/*
* Generate lists of code addresses where slabcache objects are allocated
* and freed.
*/
struct location {
unsigned long count;
unsigned long addr;
long long sum_time;
long min_time;
long max_time;
long min_pid;
long max_pid;
DECLARE_BITMAP(cpus, NR_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;
unsigned long 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;
cpumask_set_cpu(track->cpu,
to_cpumask(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;
cpumask_clear(to_cpumask(l->cpus));
cpumask_set_cpu(track->cpu, to_cpumask(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);
void *p;
unsigned long *map;
map = get_map(s, page);
for_each_object(p, s, addr, page->objects)
if (!test_bit(__obj_to_index(s, addr, p), map))
add_location(t, s, get_track(s, p, alloc));
put_map(map);
}
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;
struct kmem_cache_node *n;
if (!alloc_loc_track(&t, PAGE_SIZE / sizeof(struct location),
GFP_KERNEL)) {
return sprintf(buf, "Out of memory\n");
}
/* Push back cpu slabs */
flush_all(s);
for_each_kmem_cache_node(s, node, n) {
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, slab_list)
process_slab(&t, s, page, alloc);
list_for_each_entry(page, &n->full, slab_list)
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 - KSYM_SYMBOL_LEN - 100)
break;
len += sprintf(buf + len, "%7ld ", l->count);
if (l->addr)
len += sprintf(buf + len, "%pS", (void *)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 &&
!cpumask_empty(to_cpumask(l->cpus)) &&
len < PAGE_SIZE - 60)
len += scnprintf(buf + len, PAGE_SIZE - len - 50,
" cpus=%*pbl",
cpumask_pr_args(to_cpumask(l->cpus)));
if (nr_online_nodes > 1 && !nodes_empty(l->nodes) &&
len < PAGE_SIZE - 60)
len += scnprintf(buf + len, PAGE_SIZE - len - 50,
" nodes=%*pbl",
nodemask_pr_args(&l->nodes));
len += sprintf(buf + len, "\n");
}
free_loc_track(&t);
if (!t.count)
len += sprintf(buf, "No data\n");
return len;
}
#endif /* CONFIG_SLUB_DEBUG */
#ifdef SLUB_RESILIENCY_TEST
static void __init resiliency_test(void)
{
u8 *p;
int type = KMALLOC_NORMAL;
BUILD_BUG_ON(KMALLOC_MIN_SIZE > 16 || KMALLOC_SHIFT_HIGH < 10);
pr_err("SLUB resiliency testing\n");
pr_err("-----------------------\n");
pr_err("A. Corruption after allocation\n");
p = kzalloc(16, GFP_KERNEL);
p[16] = 0x12;
pr_err("\n1. kmalloc-16: Clobber Redzone/next pointer 0x12->0x%p\n\n",
p + 16);
validate_slab_cache(kmalloc_caches[type][4]);
/* Hmmm... The next two are dangerous */
p = kzalloc(32, GFP_KERNEL);
p[32 + sizeof(void *)] = 0x34;
pr_err("\n2. kmalloc-32: Clobber next pointer/next slab 0x34 -> -0x%p\n",
p);
pr_err("If allocated object is overwritten then not detectable\n\n");
validate_slab_cache(kmalloc_caches[type][5]);
p = kzalloc(64, GFP_KERNEL);
p += 64 + (get_cycles() & 0xff) * sizeof(void *);
*p = 0x56;
pr_err("\n3. kmalloc-64: corrupting random byte 0x56->0x%p\n",
p);
pr_err("If allocated object is overwritten then not detectable\n\n");
validate_slab_cache(kmalloc_caches[type][6]);
pr_err("\nB. Corruption after free\n");
p = kzalloc(128, GFP_KERNEL);
kfree(p);
*p = 0x78;
pr_err("1. kmalloc-128: Clobber first word 0x78->0x%p\n\n", p);
validate_slab_cache(kmalloc_caches[type][7]);
p = kzalloc(256, GFP_KERNEL);
kfree(p);
p[50] = 0x9a;
pr_err("\n2. kmalloc-256: Clobber 50th byte 0x9a->0x%p\n\n", p);
validate_slab_cache(kmalloc_caches[type][8]);
p = kzalloc(512, GFP_KERNEL);
kfree(p);
p[512] = 0xab;
pr_err("\n3. kmalloc-512: Clobber redzone 0xab->0x%p\n\n", p);
validate_slab_cache(kmalloc_caches[type][9]);
}
#else
#ifdef CONFIG_SYSFS
static void resiliency_test(void) {};
#endif
#endif /* SLUB_RESILIENCY_TEST */
#ifdef CONFIG_SYSFS
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)
#ifdef CONFIG_MEMCG
static bool memcg_sysfs_enabled = IS_ENABLED(CONFIG_SLUB_MEMCG_SYSFS_ON);
static int __init setup_slub_memcg_sysfs(char *str)
{
int v;
if (get_option(&str, &v) > 0)
memcg_sysfs_enabled = v;
return 1;
}
__setup("slub_memcg_sysfs=", setup_slub_memcg_sysfs);
#endif
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;
nodes = kcalloc(nr_node_ids, sizeof(unsigned long), GFP_KERNEL);
if (!nodes)
return -ENOMEM;
if (flags & SO_CPU) {
int cpu;
for_each_possible_cpu(cpu) {
struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab,
cpu);
int node;
struct page *page;
page = READ_ONCE(c->page);
if (!page)
continue;
node = page_to_nid(page);
if (flags & SO_TOTAL)
x = page->objects;
else if (flags & SO_OBJECTS)
x = page->inuse;
else
x = 1;
total += x;
nodes[node] += x;
page = slub_percpu_partial_read_once(c);
if (page) {
node = page_to_nid(page);
if (flags & SO_TOTAL)
WARN_ON_ONCE(1);
else if (flags & SO_OBJECTS)
WARN_ON_ONCE(1);
else
x = page->pages;
total += x;
nodes[node] += x;
}
}
}
/*
* It is impossible to take "mem_hotplug_lock" here with "kernfs_mutex"
* already held which will conflict with an existing lock order:
*
* mem_hotplug_lock->slab_mutex->kernfs_mutex
*
* We don't really need mem_hotplug_lock (to hold off
* slab_mem_going_offline_callback) here because slab's memory hot
* unplug code doesn't destroy the kmem_cache->node[] data.
*/
#ifdef CONFIG_SLUB_DEBUG
if (flags & SO_ALL) {
struct kmem_cache_node *n;
for_each_kmem_cache_node(s, node, n) {
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
#endif
if (flags & SO_PARTIAL) {
struct kmem_cache_node *n;
for_each_kmem_cache_node(s, node, n) {
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 (node = 0; node < nr_node_ids; node++)
if (nodes[node])
x += sprintf(buf + x, " N%d=%lu",
node, nodes[node]);
#endif
kfree(nodes);
return x + sprintf(buf + x, "\n");
}
#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(_name, 0400, _name##_show, NULL)
#define SLAB_ATTR(_name) \
static struct slab_attribute _name##_attr = \
__ATTR(_name, 0600, _name##_show, _name##_store)
static ssize_t slab_size_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%u\n", s->size);
}
SLAB_ATTR_RO(slab_size);
static ssize_t align_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%u\n", s->align);
}
SLAB_ATTR_RO(align);
static ssize_t object_size_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%u\n", s->object_size);
}
SLAB_ATTR_RO(object_size);
static ssize_t objs_per_slab_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%u\n", oo_objects(s->oo));
}
SLAB_ATTR_RO(objs_per_slab);
static ssize_t order_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%u\n", oo_order(s->oo));
}
SLAB_ATTR_RO(order);
static ssize_t min_partial_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%lu\n", s->min_partial);
}
static ssize_t min_partial_store(struct kmem_cache *s, const char *buf,
size_t length)
{
unsigned long min;
int err;
err = kstrtoul(buf, 10, &min);
if (err)
return err;
set_min_partial(s, min);
return length;
}
SLAB_ATTR(min_partial);
static ssize_t cpu_partial_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%u\n", slub_cpu_partial(s));
}
static ssize_t cpu_partial_store(struct kmem_cache *s, const char *buf,
size_t length)
{
unsigned int objects;
int err;
err = kstrtouint(buf, 10, &objects);
if (err)
return err;
if (objects && !kmem_cache_has_cpu_partial(s))
return -EINVAL;
slub_set_cpu_partial(s, objects);
flush_all(s);
return length;
}
SLAB_ATTR(cpu_partial);
static ssize_t ctor_show(struct kmem_cache *s, char *buf)
{
if (!s->ctor)
return 0;
return sprintf(buf, "%pS\n", s->ctor);
}
SLAB_ATTR_RO(ctor);
static ssize_t aliases_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", s->refcount < 0 ? 0 : s->refcount - 1);
}
SLAB_ATTR_RO(aliases);
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 slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
{
int objects = 0;
int pages = 0;
int cpu;
int len;
for_each_online_cpu(cpu) {
struct page *page;
page = slub_percpu_partial(per_cpu_ptr(s->cpu_slab, cpu));
if (page) {
pages += page->pages;
objects += page->pobjects;
}
}
len = sprintf(buf, "%d(%d)", objects, pages);
#ifdef CONFIG_SMP
for_each_online_cpu(cpu) {
struct page *page;
page = slub_percpu_partial(per_cpu_ptr(s->cpu_slab, cpu));
if (page && len < PAGE_SIZE - 20)
len += sprintf(buf + len, " C%d=%d(%d)", cpu,
page->pobjects, page->pages);
}
#endif
return len + sprintf(buf + len, "\n");
}
SLAB_ATTR_RO(slabs_cpu_partial);
static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_RECLAIM_ACCOUNT));
}
SLAB_ATTR_RO(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 usersize_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%u\n", s->usersize);
}
SLAB_ATTR_RO(usersize);
static ssize_t destroy_by_rcu_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_TYPESAFE_BY_RCU));
}
SLAB_ATTR_RO(destroy_by_rcu);
#ifdef CONFIG_SLUB_DEBUG
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 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_CONSISTENCY_CHECKS));
}
SLAB_ATTR_RO(sanity_checks);
static ssize_t trace_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_TRACE));
}
SLAB_ATTR_RO(trace);
static ssize_t red_zone_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_RED_ZONE));
}
SLAB_ATTR_RO(red_zone);
static ssize_t poison_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_POISON));
}
SLAB_ATTR_RO(poison);
static ssize_t store_user_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_STORE_USER));
}
SLAB_ATTR_RO(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 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);
#endif /* CONFIG_SLUB_DEBUG */
#ifdef CONFIG_FAILSLAB
static ssize_t failslab_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%d\n", !!(s->flags & SLAB_FAILSLAB));
}
SLAB_ATTR_RO(failslab);
#endif
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')
kmem_cache_shrink(s);
else
return -EINVAL;
return length;
}
SLAB_ATTR(shrink);
#ifdef CONFIG_NUMA
static ssize_t remote_node_defrag_ratio_show(struct kmem_cache *s, char *buf)
{
return sprintf(buf, "%u\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)
{
unsigned int ratio;
int err;
err = kstrtouint(buf, 10, &ratio);
if (err)
return err;
if (ratio > 100)
return -ERANGE;
s->remote_node_defrag_ratio = ratio * 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_array(nr_cpu_ids, sizeof(int), GFP_KERNEL);
if (!data)
return -ENOMEM;
for_each_online_cpu(cpu) {
unsigned x = per_cpu_ptr(s->cpu_slab, 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");
}
static void clear_stat(struct kmem_cache *s, enum stat_item si)
{
int cpu;
for_each_online_cpu(cpu)
per_cpu_ptr(s->cpu_slab, cpu)->stat[si] = 0;
}
#define STAT_ATTR(si, text) \
static ssize_t text##_show(struct kmem_cache *s, char *buf) \
{ \
return show_stat(s, buf, si); \
} \
static ssize_t text##_store(struct kmem_cache *s, \
const char *buf, size_t length) \
{ \
if (buf[0] != '0') \
return -EINVAL; \
clear_stat(s, si); \
return length; \
} \
SLAB_ATTR(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(ALLOC_NODE_MISMATCH, alloc_node_mismatch);
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(DEACTIVATE_BYPASS, deactivate_bypass);
STAT_ATTR(ORDER_FALLBACK, order_fallback);
STAT_ATTR(CMPXCHG_DOUBLE_CPU_FAIL, cmpxchg_double_cpu_fail);
STAT_ATTR(CMPXCHG_DOUBLE_FAIL, cmpxchg_double_fail);
STAT_ATTR(CPU_PARTIAL_ALLOC, cpu_partial_alloc);
STAT_ATTR(CPU_PARTIAL_FREE, cpu_partial_free);
STAT_ATTR(CPU_PARTIAL_NODE, cpu_partial_node);
STAT_ATTR(CPU_PARTIAL_DRAIN, cpu_partial_drain);
#endif /* CONFIG_SLUB_STATS */
static struct attribute *slab_attrs[] = {
&slab_size_attr.attr,
&object_size_attr.attr,
&objs_per_slab_attr.attr,
&order_attr.attr,
&min_partial_attr.attr,
&cpu_partial_attr.attr,
&objects_attr.attr,
&objects_partial_attr.attr,
&partial_attr.attr,
&cpu_slabs_attr.attr,
&ctor_attr.attr,
&aliases_attr.attr,
&align_attr.attr,
&hwcache_align_attr.attr,
&reclaim_account_attr.attr,
&destroy_by_rcu_attr.attr,
&shrink_attr.attr,
&slabs_cpu_partial_attr.attr,
#ifdef CONFIG_SLUB_DEBUG
&total_objects_attr.attr,
&slabs_attr.attr,
&sanity_checks_attr.attr,
&trace_attr.attr,
&red_zone_attr.attr,
&poison_attr.attr,
&store_user_attr.attr,
&validate_attr.attr,
&alloc_calls_attr.attr,
&free_calls_attr.attr,
#endif
#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,
&alloc_node_mismatch_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,
&deactivate_bypass_attr.attr,
&order_fallback_attr.attr,
&cmpxchg_double_fail_attr.attr,
&cmpxchg_double_cpu_fail_attr.attr,
&cpu_partial_alloc_attr.attr,
&cpu_partial_free_attr.attr,
&cpu_partial_node_attr.attr,
&cpu_partial_drain_attr.attr,
#endif
#ifdef CONFIG_FAILSLAB
&failslab_attr.attr,
#endif
&usersize_attr.attr,
NULL
};
static const 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 *k)
{
slab_kmem_cache_release(to_slab(k));
}
static const 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 struct kset *slab_kset;
static inline struct kset *cache_kset(struct kmem_cache *s)
{
return 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_CACHE_DMA32)
*p++ = 'D';
if (s->flags & SLAB_RECLAIM_ACCOUNT)
*p++ = 'a';
if (s->flags & SLAB_CONSISTENCY_CHECKS)
*p++ = 'F';
if (s->flags & SLAB_ACCOUNT)
*p++ = 'A';
if (p != name + 1)
*p++ = '-';
p += sprintf(p, "%07u", 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;
struct kset *kset = cache_kset(s);
int unmergeable = slab_unmergeable(s);
if (!kset) {
kobject_init(&s->kobj, &slab_ktype);
return 0;
}
if (!unmergeable && disable_higher_order_debug &&
(slub_debug & DEBUG_METADATA_FLAGS))
unmergeable = 1;
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 = kset;
err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name);
if (err) {
kobject_put(&s->kobj);
goto out;
}
err = sysfs_create_group(&s->kobj, &slab_attr_group);
if (err)
goto out_del_kobj;
if (!unmergeable) {
/* Setup first alias */
sysfs_slab_alias(s, s->name);
}
out:
if (!unmergeable)
kfree(name);
return err;
out_del_kobj:
kobject_del(&s->kobj);
goto out;
}
void sysfs_slab_unlink(struct kmem_cache *s)
{
if (slab_state >= FULL)
kobject_del(&s->kobj);
}
void sysfs_slab_release(struct kmem_cache *s)
{
if (slab_state >= FULL)
kobject_put(&s->kobj);
}
/*
* Need to buffer aliases during bootup until sysfs becomes
* available lest we lose 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 == FULL) {
/*
* 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;
mutex_lock(&slab_mutex);
slab_kset = kset_create_and_add("slab", NULL, kernel_kobj);
if (!slab_kset) {
mutex_unlock(&slab_mutex);
pr_err("Cannot register slab subsystem.\n");
return -ENOSYS;
}
slab_state = FULL;
list_for_each_entry(s, &slab_caches, list) {
err = sysfs_slab_add(s);
if (err)
pr_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)
pr_err("SLUB: Unable to add boot slab alias %s to sysfs\n",
al->name);
kfree(al);
}
mutex_unlock(&slab_mutex);
resiliency_test();
return 0;
}
__initcall(slab_sysfs_init);
#endif /* CONFIG_SYSFS */
/*
* The /proc/slabinfo ABI
*/
#ifdef CONFIG_SLUB_DEBUG
void get_slabinfo(struct kmem_cache *s, struct slabinfo *sinfo)
{
unsigned long nr_slabs = 0;
unsigned long nr_objs = 0;
unsigned long nr_free = 0;
int node;
struct kmem_cache_node *n;
for_each_kmem_cache_node(s, node, n) {
nr_slabs += node_nr_slabs(n);
nr_objs += node_nr_objs(n);
nr_free += count_partial(n, count_free);
}
sinfo->active_objs = nr_objs - nr_free;
sinfo->num_objs = nr_objs;
sinfo->active_slabs = nr_slabs;
sinfo->num_slabs = nr_slabs;
sinfo->objects_per_slab = oo_objects(s->oo);
sinfo->cache_order = oo_order(s->oo);
}
void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s)
{
}
ssize_t slabinfo_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos)
{
return -EIO;
}
#endif /* CONFIG_SLUB_DEBUG */
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