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linux/mm/slub.c
Vlastimil Babka 1a1c4e4576 Merge branch 'slab/for-6.9/slab-flag-cleanups' into slab/for-linus 
Merge a series from myself that replaces hardcoded SLAB_ cache flag
values with an enum, and explicitly deprecates the SLAB_MEM_SPREAD flag
that is a no-op sine SLAB removal.
2024-03-12 10:16:56 +01:00

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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 operations
* 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> /* mm_account_reclaimed_pages() */
#include <linux/module.h>
#include <linux/bit_spinlock.h>
#include <linux/interrupt.h>
#include <linux/swab.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/kmsan.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/mempolicy.h>
#include <linux/ctype.h>
#include <linux/stackdepot.h>
#include <linux/debugobjects.h>
#include <linux/kallsyms.h>
#include <linux/kfence.h>
#include <linux/memory.h>
#include <linux/math64.h>
#include <linux/fault-inject.h>
#include <linux/kmemleak.h>
#include <linux/stacktrace.h>
#include <linux/prefetch.h>
#include <linux/memcontrol.h>
#include <linux/random.h>
#include <kunit/test.h>
#include <kunit/test-bug.h>
#include <linux/sort.h>
#include <linux/debugfs.h>
#include <trace/events/kmem.h>
#include "internal.h"
/*
* Lock order:
* 1. slab_mutex (Global Mutex)
* 2. node->list_lock (Spinlock)
* 3. kmem_cache->cpu_slab->lock (Local lock)
* 4. slab_lock(slab) (Only on some arches)
* 5. object_map_lock (Only 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.
* Also synchronizes memory hotplug callbacks.
*
* slab_lock
*
* The slab_lock is a wrapper around the page lock, thus it is a bit
* spinlock.
*
* The slab_lock is only used on arches that do not have the ability
* to do a cmpxchg_double. It only protects:
*
* A. slab->freelist -> List of free objects in a slab
* B. slab->inuse -> Number of objects in use
* C. slab->objects -> Number of objects in slab
* D. slab->frozen -> frozen state
*
* Frozen slabs
*
* If a slab is frozen then it is exempt from list management. It is
* the cpu slab which is actively allocated from by the processor that
* froze it and it is not on any list. The processor that froze the
* slab is the one who can perform list operations on the slab. 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
* slab's freelist.
*
* CPU partial slabs
*
* The partially empty slabs cached on the CPU partial list are used
* for performance reasons, which speeds up the allocation process.
* These slabs are not frozen, but are also exempt from list management,
* by clearing the PG_workingset flag when moving out of the node
* partial list. Please see __slab_free() for more details.
*
* To sum up, the current scheme is:
* - node partial slab: PG_Workingset && !frozen
* - cpu partial slab: !PG_Workingset && !frozen
* - cpu slab: !PG_Workingset && frozen
* - full slab: !PG_Workingset && !frozen
*
* list_lock
*
* 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.
*
* For debug caches, all allocations are forced to go through a list_lock
* protected region to serialize against concurrent validation.
*
* cpu_slab->lock local lock
*
* This locks protect slowpath manipulation of all kmem_cache_cpu fields
* except the stat counters. This is a percpu structure manipulated only by
* the local cpu, so the lock protects against being preempted or interrupted
* by an irq. Fast path operations rely on lockless operations instead.
*
* On PREEMPT_RT, the local lock neither disables interrupts nor preemption
* which means the lockless fastpath cannot be used as it might interfere with
* an in-progress slow path operations. In this case the local lock is always
* taken but it still utilizes the freelist for the common operations.
*
* lockless fastpaths
*
* The fast path allocation (slab_alloc_node()) and freeing (do_slab_free())
* are fully lockless when satisfied from the percpu slab (and when
* cmpxchg_double is possible to use, otherwise slab_lock is taken).
* They also don't disable preemption or migration or irqs. They rely on
* the transaction id (tid) field to detect being preempted or moved to
* another cpu.
*
* irq, preemption, migration considerations
*
* Interrupts are disabled as part of list_lock or local_lock operations, or
* around the slab_lock operation, in order to make the slab allocator safe
* to use in the context of an irq.
*
* In addition, preemption (or migration on PREEMPT_RT) is disabled in the
* allocation slowpath, bulk allocation, and put_cpu_partial(), so that the
* local cpu doesn't change in the process and e.g. the kmem_cache_cpu pointer
* doesn't have to be revalidated in each section protected by the local lock.
*
* 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.
*
* slab->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.
*/
/*
* We could simply use migrate_disable()/enable() but as long as it's a
* function call even on !PREEMPT_RT, use inline preempt_disable() there.
*/
#ifndef CONFIG_PREEMPT_RT
#define slub_get_cpu_ptr(var) get_cpu_ptr(var)
#define slub_put_cpu_ptr(var) put_cpu_ptr(var)
#define USE_LOCKLESS_FAST_PATH() (true)
#else
#define slub_get_cpu_ptr(var) \
({ \
migrate_disable(); \
this_cpu_ptr(var); \
})
#define slub_put_cpu_ptr(var) \
do { \
(void)(var); \
migrate_enable(); \
} while (0)
#define USE_LOCKLESS_FAST_PATH() (false)
#endif
#ifndef CONFIG_SLUB_TINY
#define __fastpath_inline __always_inline
#else
#define __fastpath_inline
#endif
#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 /* CONFIG_SLUB_DEBUG */
/* Structure holding parameters for get_partial() call chain */
struct partial_context {
gfp_t flags;
unsigned int orig_size;
void *object;
};
static inline bool kmem_cache_debug(struct kmem_cache *s)
{
return kmem_cache_debug_flags(s, SLAB_DEBUG_FLAGS);
}
static inline bool slub_debug_orig_size(struct kmem_cache *s)
{
return (kmem_cache_debug_flags(s, SLAB_STORE_USER) &&
(s->flags & SLAB_KMALLOC));
}
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 log cmpxchg failures */
#undef SLUB_DEBUG_CMPXCHG
#ifndef CONFIG_SLUB_TINY
/*
* Minimum 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
#else
#define MIN_PARTIAL 0
#define MAX_PARTIAL 0
#endif
#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 slab_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 slab.objects is u15 */
/* Internal SLUB flags */
/* Poison object */
#define __OBJECT_POISON __SLAB_FLAG_BIT(_SLAB_OBJECT_POISON)
/* Use cmpxchg_double */
#ifdef system_has_freelist_aba
#define __CMPXCHG_DOUBLE __SLAB_FLAG_BIT(_SLAB_CMPXCHG_DOUBLE)
#else
#define __CMPXCHG_DOUBLE __SLAB_FLAG_UNUSED
#endif
/*
* Tracking user of a slab.
*/
#define TRACK_ADDRS_COUNT 16
struct track {
unsigned long addr; /* Called from address */
#ifdef CONFIG_STACKDEPOT
depot_stack_handle_t handle;
#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 SLAB_SUPPORTS_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
#if defined(CONFIG_DEBUG_FS) && defined(CONFIG_SLUB_DEBUG)
static void debugfs_slab_add(struct kmem_cache *);
#else
static inline void debugfs_slab_add(struct kmem_cache *s) { }
#endif
enum stat_item {
ALLOC_FASTPATH, /* Allocation from cpu slab */
ALLOC_SLOWPATH, /* Allocation by getting a new cpu slab */
FREE_FASTPATH, /* Free to cpu slab */
FREE_SLOWPATH, /* Freeing not to cpu slab */
FREE_FROZEN, /* Freeing to frozen slab */
FREE_ADD_PARTIAL, /* Freeing moves slab to partial list */
FREE_REMOVE_PARTIAL, /* Freeing removes last object */
ALLOC_FROM_PARTIAL, /* Cpu slab acquired from node partial list */
ALLOC_SLAB, /* Cpu slab acquired from page allocator */
ALLOC_REFILL, /* Refill cpu slab from slab freelist */
ALLOC_NODE_MISMATCH, /* Switching cpu slab */
FREE_SLAB, /* Slab freed to the page allocator */
CPUSLAB_FLUSH, /* Abandoning of the cpu slab */
DEACTIVATE_FULL, /* Cpu slab was full when deactivated */
DEACTIVATE_EMPTY, /* Cpu slab was empty when deactivated */
DEACTIVATE_TO_HEAD, /* Cpu slab was moved to the head of partials */
DEACTIVATE_TO_TAIL, /* Cpu slab was moved to the tail of partials */
DEACTIVATE_REMOTE_FREES,/* Slab contained remotely freed objects */
DEACTIVATE_BYPASS, /* Implicit deactivation */
ORDER_FALLBACK, /* Number of times fallback was necessary */
CMPXCHG_DOUBLE_CPU_FAIL,/* Failures of this_cpu_cmpxchg_double */
CMPXCHG_DOUBLE_FAIL, /* Failures of slab freelist update */
CPU_PARTIAL_ALLOC, /* Used cpu partial on alloc */
CPU_PARTIAL_FREE, /* Refill cpu partial on free */
CPU_PARTIAL_NODE, /* Refill cpu partial from node partial */
CPU_PARTIAL_DRAIN, /* Drain cpu partial to node partial */
NR_SLUB_STAT_ITEMS
};
#ifndef CONFIG_SLUB_TINY
/*
* When changing the layout, make sure freelist and tid are still compatible
* with this_cpu_cmpxchg_double() alignment requirements.
*/
struct kmem_cache_cpu {
union {
struct {
void **freelist; /* Pointer to next available object */
unsigned long tid; /* Globally unique transaction id */
};
freelist_aba_t freelist_tid;
};
struct slab *slab; /* The slab from which we are allocating */
#ifdef CONFIG_SLUB_CPU_PARTIAL
struct slab *partial; /* Partially allocated slabs */
#endif
local_lock_t lock; /* Protects the fields above */
#ifdef CONFIG_SLUB_STATS
unsigned int stat[NR_SLUB_STAT_ITEMS];
#endif
};
#endif /* CONFIG_SLUB_TINY */
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
}
static inline
void stat_add(const struct kmem_cache *s, enum stat_item si, int v)
{
#ifdef CONFIG_SLUB_STATS
raw_cpu_add(s->cpu_slab->stat[si], v);
#endif
}
/*
* The slab lists for all objects.
*/
struct kmem_cache_node {
spinlock_t list_lock;
unsigned long nr_partial;
struct list_head partial;
#ifdef CONFIG_SLUB_DEBUG
atomic_long_t nr_slabs;
atomic_long_t total_objects;
struct list_head full;
#endif
};
static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node)
{
return s->node[node];
}
/*
* Iterator over all nodes. The body will be executed for each node that has
* a kmem_cache_node structure allocated (which is true for all online nodes)
*/
#define for_each_kmem_cache_node(__s, __node, __n) \
for (__node = 0; __node < nr_node_ids; __node++) \
if ((__n = get_node(__s, __node)))
/*
* Tracks for which NUMA nodes we have kmem_cache_nodes allocated.
* Corresponds to node_state[N_NORMAL_MEMORY], but can temporarily
* differ during memory hotplug/hotremove operations.
* Protected by slab_mutex.
*/
static nodemask_t slab_nodes;
#ifndef CONFIG_SLUB_TINY
/*
* Workqueue used for flush_cpu_slab().
*/
static struct workqueue_struct *flushwq;
#endif
/********************************************************************
* Core slab cache functions
*******************************************************************/
/*
* freeptr_t represents a SLUB freelist pointer, which might be encoded
* and not dereferenceable if CONFIG_SLAB_FREELIST_HARDENED is enabled.
*/
typedef struct { unsigned long v; } freeptr_t;
/*
* 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 freeptr_t freelist_ptr_encode(const struct kmem_cache *s,
void *ptr, unsigned long ptr_addr)
{
unsigned long encoded;
#ifdef CONFIG_SLAB_FREELIST_HARDENED
encoded = (unsigned long)ptr ^ s->random ^ swab(ptr_addr);
#else
encoded = (unsigned long)ptr;
#endif
return (freeptr_t){.v = encoded};
}
static inline void *freelist_ptr_decode(const struct kmem_cache *s,
freeptr_t ptr, unsigned long ptr_addr)
{
void *decoded;
#ifdef CONFIG_SLAB_FREELIST_HARDENED
decoded = (void *)(ptr.v ^ s->random ^ swab(ptr_addr));
#else
decoded = (void *)ptr.v;
#endif
return decoded;
}
static inline void *get_freepointer(struct kmem_cache *s, void *object)
{
unsigned long ptr_addr;
freeptr_t p;
object = kasan_reset_tag(object);
ptr_addr = (unsigned long)object + s->offset;
p = *(freeptr_t *)(ptr_addr);
return freelist_ptr_decode(s, p, ptr_addr);
}
#ifndef CONFIG_SLUB_TINY
static void prefetch_freepointer(const struct kmem_cache *s, void *object)
{
prefetchw(object + s->offset);
}
#endif
/*
* When running under KMSAN, get_freepointer_safe() may return an uninitialized
* pointer value in the case the current thread loses the race for the next
* memory chunk in the freelist. In that case this_cpu_cmpxchg_double() in
* slab_alloc_node() will fail, so the uninitialized value won't be used, but
* KMSAN will still check all arguments of cmpxchg because of imperfect
* handling of inline assembly.
* To work around this problem, we apply __no_kmsan_checks to ensure that
* get_freepointer_safe() returns initialized memory.
*/
__no_kmsan_checks
static inline void *get_freepointer_safe(struct kmem_cache *s, void *object)
{
unsigned long freepointer_addr;
freeptr_t p;
if (!debug_pagealloc_enabled_static())
return get_freepointer(s, object);
object = kasan_reset_tag(object);
freepointer_addr = (unsigned long)object + s->offset;
copy_from_kernel_nofault(&p, (freeptr_t *)freepointer_addr, sizeof(p));
return freelist_ptr_decode(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
freeptr_addr = (unsigned long)kasan_reset_tag((void *)freeptr_addr);
*(freeptr_t *)freeptr_addr = freelist_ptr_encode(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;
}
#ifdef CONFIG_SLUB_CPU_PARTIAL
static void slub_set_cpu_partial(struct kmem_cache *s, unsigned int nr_objects)
{
unsigned int nr_slabs;
s->cpu_partial = nr_objects;
/*
* We take the number of objects but actually limit the number of
* slabs on the per cpu partial list, in order to limit excessive
* growth of the list. For simplicity we assume that the slabs will
* be half-full.
*/
nr_slabs = DIV_ROUND_UP(nr_objects * 2, oo_objects(s->oo));
s->cpu_partial_slabs = nr_slabs;
}
#else
static inline void
slub_set_cpu_partial(struct kmem_cache *s, unsigned int nr_objects)
{
}
#endif /* CONFIG_SLUB_CPU_PARTIAL */
/*
* Per slab locking using the pagelock
*/
static __always_inline void slab_lock(struct slab *slab)
{
struct page *page = slab_page(slab);
VM_BUG_ON_PAGE(PageTail(page), page);
bit_spin_lock(PG_locked, &page->flags);
}
static __always_inline void slab_unlock(struct slab *slab)
{
struct page *page = slab_page(slab);
VM_BUG_ON_PAGE(PageTail(page), page);
bit_spin_unlock(PG_locked, &page->flags);
}
static inline bool
__update_freelist_fast(struct slab *slab,
void *freelist_old, unsigned long counters_old,
void *freelist_new, unsigned long counters_new)
{
#ifdef system_has_freelist_aba
freelist_aba_t old = { .freelist = freelist_old, .counter = counters_old };
freelist_aba_t new = { .freelist = freelist_new, .counter = counters_new };
return try_cmpxchg_freelist(&slab->freelist_counter.full, &old.full, new.full);
#else
return false;
#endif
}
static inline bool
__update_freelist_slow(struct slab *slab,
void *freelist_old, unsigned long counters_old,
void *freelist_new, unsigned long counters_new)
{
bool ret = false;
slab_lock(slab);
if (slab->freelist == freelist_old &&
slab->counters == counters_old) {
slab->freelist = freelist_new;
slab->counters = counters_new;
ret = true;
}
slab_unlock(slab);
return ret;
}
/*
* Interrupts must be disabled (for the fallback code to work right), typically
* by an _irqsave() lock variant. On PREEMPT_RT the preempt_disable(), which is
* part of bit_spin_lock(), is sufficient because the policy is not to allow any
* allocation/ free operation in hardirq context. Therefore nothing can
* interrupt the operation.
*/
static inline bool __slab_update_freelist(struct kmem_cache *s, struct slab *slab,
void *freelist_old, unsigned long counters_old,
void *freelist_new, unsigned long counters_new,
const char *n)
{
bool ret;
if (USE_LOCKLESS_FAST_PATH())
lockdep_assert_irqs_disabled();
if (s->flags & __CMPXCHG_DOUBLE) {
ret = __update_freelist_fast(slab, freelist_old, counters_old,
freelist_new, counters_new);
} else {
ret = __update_freelist_slow(slab, freelist_old, counters_old,
freelist_new, counters_new);
}
if (likely(ret))
return true;
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 slab_update_freelist(struct kmem_cache *s, struct slab *slab,
void *freelist_old, unsigned long counters_old,
void *freelist_new, unsigned long counters_new,
const char *n)
{
bool ret;
if (s->flags & __CMPXCHG_DOUBLE) {
ret = __update_freelist_fast(slab, freelist_old, counters_old,
freelist_new, counters_new);
} else {
unsigned long flags;
local_irq_save(flags);
ret = __update_freelist_slow(slab, freelist_old, counters_old,
freelist_new, counters_new);
local_irq_restore(flags);
}
if (likely(ret))
return true;
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);
static void __fill_map(unsigned long *obj_map, struct kmem_cache *s,
struct slab *slab)
{
void *addr = slab_address(slab);
void *p;
bitmap_zero(obj_map, slab->objects);
for (p = slab->freelist; p; p = get_freepointer(s, p))
set_bit(__obj_to_index(s, addr, p), obj_map);
}
#if IS_ENABLED(CONFIG_KUNIT)
static bool slab_add_kunit_errors(void)
{
struct kunit_resource *resource;
if (!kunit_get_current_test())
return false;
resource = kunit_find_named_resource(current->kunit_test, "slab_errors");
if (!resource)
return false;
(*(int *)resource->data)++;
kunit_put_resource(resource);
return true;
}
#else
static inline bool slab_add_kunit_errors(void) { return false; }
#endif
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 slab *slab, void *object)
{
void *base;
if (!object)
return 1;
base = slab_address(slab);
object = kasan_reset_tag(object);
object = restore_red_left(s, object);
if (object < base || object >= base + slab->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, kasan_reset_tag((void *)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 kasan_reset_tag(p + alloc);
}
#ifdef CONFIG_STACKDEPOT
static noinline depot_stack_handle_t set_track_prepare(void)
{
depot_stack_handle_t handle;
unsigned long entries[TRACK_ADDRS_COUNT];
unsigned int nr_entries;
nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 3);
handle = stack_depot_save(entries, nr_entries, GFP_NOWAIT);
return handle;
}
#else
static inline depot_stack_handle_t set_track_prepare(void)
{
return 0;
}
#endif
static void set_track_update(struct kmem_cache *s, void *object,
enum track_item alloc, unsigned long addr,
depot_stack_handle_t handle)
{
struct track *p = get_track(s, object, alloc);
#ifdef CONFIG_STACKDEPOT
p->handle = handle;
#endif
p->addr = addr;
p->cpu = smp_processor_id();
p->pid = current->pid;
p->when = jiffies;
}
static __always_inline void set_track(struct kmem_cache *s, void *object,
enum track_item alloc, unsigned long addr)
{
depot_stack_handle_t handle = set_track_prepare();
set_track_update(s, object, alloc, addr, handle);
}
static void init_tracking(struct kmem_cache *s, void *object)
{
struct track *p;
if (!(s->flags & SLAB_STORE_USER))
return;
p = get_track(s, object, TRACK_ALLOC);
memset(p, 0, 2*sizeof(struct track));
}
static void print_track(const char *s, struct track *t, unsigned long pr_time)
{
depot_stack_handle_t handle __maybe_unused;
if (!t->addr)
return;
pr_err("%s in %pS age=%lu cpu=%u pid=%d\n",
s, (void *)t->addr, pr_time - t->when, t->cpu, t->pid);
#ifdef CONFIG_STACKDEPOT
handle = READ_ONCE(t->handle);
if (handle)
stack_depot_print(handle);
else
pr_err("object allocation/free stack trace missing\n");
#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_slab_info(const struct slab *slab)
{
struct folio *folio = (struct folio *)slab_folio(slab);
pr_err("Slab 0x%p objects=%u used=%u fp=0x%p flags=%pGp\n",
slab, slab->objects, slab->inuse, slab->freelist,
folio_flags(folio, 0));
}
/*
* kmalloc caches has fixed sizes (mostly power of 2), and kmalloc() API
* family will round up the real request size to these fixed ones, so
* there could be an extra area than what is requested. Save the original
* request size in the meta data area, for better debug and sanity check.
*/
static inline void set_orig_size(struct kmem_cache *s,
void *object, unsigned int orig_size)
{
void *p = kasan_reset_tag(object);
unsigned int kasan_meta_size;
if (!slub_debug_orig_size(s))
return;
/*
* KASAN can save its free meta data inside of the object at offset 0.
* If this meta data size is larger than 'orig_size', it will overlap
* the data redzone in [orig_size+1, object_size]. Thus, we adjust
* 'orig_size' to be as at least as big as KASAN's meta data.
*/
kasan_meta_size = kasan_metadata_size(s, true);
if (kasan_meta_size > orig_size)
orig_size = kasan_meta_size;
p += get_info_end(s);
p += sizeof(struct track) * 2;
*(unsigned int *)p = orig_size;
}
static inline unsigned int get_orig_size(struct kmem_cache *s, void *object)
{
void *p = kasan_reset_tag(object);
if (!slub_debug_orig_size(s))
return s->object_size;
p += get_info_end(s);
p += sizeof(struct track) * 2;
return *(unsigned int *)p;
}
void skip_orig_size_check(struct kmem_cache *s, const void *object)
{
set_orig_size(s, (void *)object, s->object_size);
}
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");
va_end(args);
}
__printf(2, 3)
static void slab_fix(struct kmem_cache *s, char *fmt, ...)
{
struct va_format vaf;
va_list args;
if (slab_add_kunit_errors())
return;
va_start(args, fmt);
vaf.fmt = fmt;
vaf.va = &args;
pr_err("FIX %s: %pV\n", s->name, &vaf);
va_end(args);
}
static void print_trailer(struct kmem_cache *s, struct slab *slab, u8 *p)
{
unsigned int off; /* Offset of last byte */
u8 *addr = slab_address(slab);
print_tracking(s, p);
print_slab_info(slab);
pr_err("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);
if (slub_debug_orig_size(s))
off += sizeof(unsigned int);
off += kasan_metadata_size(s, false);
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();
}
static void object_err(struct kmem_cache *s, struct slab *slab,
u8 *object, char *reason)
{
if (slab_add_kunit_errors())
return;
slab_bug(s, "%s", reason);
print_trailer(s, slab, object);
add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
}
static bool freelist_corrupted(struct kmem_cache *s, struct slab *slab,
void **freelist, void *nextfree)
{
if ((s->flags & SLAB_CONSISTENCY_CHECKS) &&
!check_valid_pointer(s, slab, nextfree) && freelist) {
object_err(s, slab, *freelist, "Freechain corrupt");
*freelist = NULL;
slab_fix(s, "Isolate corrupted freechain");
return true;
}
return false;
}
static __printf(3, 4) void slab_err(struct kmem_cache *s, struct slab *slab,
const char *fmt, ...)
{
va_list args;
char buf[100];
if (slab_add_kunit_errors())
return;
va_start(args, fmt);
vsnprintf(buf, sizeof(buf), fmt, args);
va_end(args);
slab_bug(s, "%s", buf);
print_slab_info(slab);
dump_stack();
add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
}
static void init_object(struct kmem_cache *s, void *object, u8 val)
{
u8 *p = kasan_reset_tag(object);
unsigned int poison_size = s->object_size;
if (s->flags & SLAB_RED_ZONE) {
memset(p - s->red_left_pad, val, s->red_left_pad);
if (slub_debug_orig_size(s) && val == SLUB_RED_ACTIVE) {
/*
* Redzone the extra allocated space by kmalloc than
* requested, and the poison size will be limited to
* the original request size accordingly.
*/
poison_size = get_orig_size(s, object);
}
}
if (s->flags & __OBJECT_POISON) {
memset(p, POISON_FREE, poison_size - 1);
p[poison_size - 1] = POISON_END;
}
if (s->flags & SLAB_RED_ZONE)
memset(p + poison_size, val, s->inuse - poison_size);
}
static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
void *from, void *to)
{
slab_fix(s, "Restoring %s 0x%p-0x%p=0x%x", message, from, to - 1, data);
memset(from, data, to - from);
}
static int check_bytes_and_report(struct kmem_cache *s, struct slab *slab,
u8 *object, char *what,
u8 *start, unsigned int value, unsigned int bytes)
{
u8 *fault;
u8 *end;
u8 *addr = slab_address(slab);
metadata_access_enable();
fault = memchr_inv(kasan_reset_tag(start), value, bytes);
metadata_access_disable();
if (!fault)
return 1;
end = start + bytes;
while (end > fault && end[-1] == value)
end--;
if (slab_add_kunit_errors())
goto skip_bug_print;
slab_bug(s, "%s overwritten", what);
pr_err("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, slab, object);
add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
skip_bug_print:
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. Original request size for kmalloc object (SLAB_STORE_USER enabled)
* D. Padding to reach required alignment boundary or at minimum
* 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 slab *slab, 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);
if (s->flags & SLAB_KMALLOC)
off += sizeof(unsigned int);
}
off += kasan_metadata_size(s, false);
if (size_from_object(s) == off)
return 1;
return check_bytes_and_report(s, slab, p, "Object padding",
p + off, POISON_INUSE, size_from_object(s) - off);
}
/* Check the pad bytes at the end of a slab page */
static void slab_pad_check(struct kmem_cache *s, struct slab *slab)
{
u8 *start;
u8 *fault;
u8 *end;
u8 *pad;
int length;
int remainder;
if (!(s->flags & SLAB_POISON))
return;
start = slab_address(slab);
length = slab_size(slab);
end = start + length;
remainder = length % s->size;
if (!remainder)
return;
pad = end - remainder;
metadata_access_enable();
fault = memchr_inv(kasan_reset_tag(pad), POISON_INUSE, remainder);
metadata_access_disable();
if (!fault)
return;
while (end > fault && end[-1] == POISON_INUSE)
end--;
slab_err(s, slab, "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);
}
static int check_object(struct kmem_cache *s, struct slab *slab,
void *object, u8 val)
{
u8 *p = object;
u8 *endobject = object + s->object_size;
unsigned int orig_size, kasan_meta_size;
if (s->flags & SLAB_RED_ZONE) {
if (!check_bytes_and_report(s, slab, object, "Left Redzone",
object - s->red_left_pad, val, s->red_left_pad))
return 0;
if (!check_bytes_and_report(s, slab, object, "Right Redzone",
endobject, val, s->inuse - s->object_size))
return 0;
if (slub_debug_orig_size(s) && val == SLUB_RED_ACTIVE) {
orig_size = get_orig_size(s, object);
if (s->object_size > orig_size &&
!check_bytes_and_report(s, slab, object,
"kmalloc Redzone", p + orig_size,
val, s->object_size - orig_size)) {
return 0;
}
}
} else {
if ((s->flags & SLAB_POISON) && s->object_size < s->inuse) {
check_bytes_and_report(s, slab, 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)) {
/*
* KASAN can save its free meta data inside of the
* object at offset 0. Thus, skip checking the part of
* the redzone that overlaps with the meta data.
*/
kasan_meta_size = kasan_metadata_size(s, true);
if (kasan_meta_size < s->object_size - 1 &&
!check_bytes_and_report(s, slab, p, "Poison",
p + kasan_meta_size, POISON_FREE,
s->object_size - kasan_meta_size - 1))
return 0;
if (kasan_meta_size < s->object_size &&
!check_bytes_and_report(s, slab, p, "End Poison",
p + s->object_size - 1, POISON_END, 1))
return 0;
}
/*
* check_pad_bytes cleans up on its own.
*/
check_pad_bytes(s, slab, 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, slab, get_freepointer(s, p))) {
object_err(s, slab, 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 slab *slab)
{
int maxobj;
if (!folio_test_slab(slab_folio(slab))) {
slab_err(s, slab, "Not a valid slab page");
return 0;
}
maxobj = order_objects(slab_order(slab), s->size);
if (slab->objects > maxobj) {
slab_err(s, slab, "objects %u > max %u",
slab->objects, maxobj);
return 0;
}
if (slab->inuse > slab->objects) {
slab_err(s, slab, "inuse %u > max %u",
slab->inuse, slab->objects);
return 0;
}
/* Slab_pad_check fixes things up after itself */
slab_pad_check(s, slab);
return 1;
}
/*
* Determine if a certain object in a slab 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 slab *slab, void *search)
{
int nr = 0;
void *fp;
void *object = NULL;
int max_objects;
fp = slab->freelist;
while (fp && nr <= slab->objects) {
if (fp == search)
return 1;
if (!check_valid_pointer(s, slab, fp)) {
if (object) {
object_err(s, slab, object,
"Freechain corrupt");
set_freepointer(s, object, NULL);
} else {
slab_err(s, slab, "Freepointer corrupt");
slab->freelist = NULL;
slab->inuse = slab->objects;
slab_fix(s, "Freelist cleared");
return 0;
}
break;
}
object = fp;
fp = get_freepointer(s, object);
nr++;
}
max_objects = order_objects(slab_order(slab), s->size);
if (max_objects > MAX_OBJS_PER_PAGE)
max_objects = MAX_OBJS_PER_PAGE;
if (slab->objects != max_objects) {
slab_err(s, slab, "Wrong number of objects. Found %d but should be %d",
slab->objects, max_objects);
slab->objects = max_objects;
slab_fix(s, "Number of objects adjusted");
}
if (slab->inuse != slab->objects - nr) {
slab_err(s, slab, "Wrong object count. Counter is %d but counted were %d",
slab->inuse, slab->objects - nr);
slab->inuse = slab->objects - nr;
slab_fix(s, "Object count adjusted");
}
return search == NULL;
}
static void trace(struct kmem_cache *s, struct slab *slab, 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, slab->inuse,
slab->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 slab *slab)
{
if (!(s->flags & SLAB_STORE_USER))
return;
lockdep_assert_held(&n->list_lock);
list_add(&slab->slab_list, &n->full);
}
static void remove_full(struct kmem_cache *s, struct kmem_cache_node *n, struct slab *slab)
{
if (!(s->flags & SLAB_STORE_USER))
return;
lockdep_assert_held(&n->list_lock);
list_del(&slab->slab_list);
}
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);
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, 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_slab_debug(struct kmem_cache *s, struct slab *slab, void *addr)
{
if (!kmem_cache_debug_flags(s, SLAB_POISON))
return;
metadata_access_enable();
memset(kasan_reset_tag(addr), POISON_INUSE, slab_size(slab));
metadata_access_disable();
}
static inline int alloc_consistency_checks(struct kmem_cache *s,
struct slab *slab, void *object)
{
if (!check_slab(s, slab))
return 0;
if (!check_valid_pointer(s, slab, object)) {
object_err(s, slab, object, "Freelist Pointer check fails");
return 0;
}
if (!check_object(s, slab, object, SLUB_RED_INACTIVE))
return 0;
return 1;
}
static noinline bool alloc_debug_processing(struct kmem_cache *s,
struct slab *slab, void *object, int orig_size)
{
if (s->flags & SLAB_CONSISTENCY_CHECKS) {
if (!alloc_consistency_checks(s, slab, object))
goto bad;
}
/* Success. Perform special debug activities for allocs */
trace(s, slab, object, 1);
set_orig_size(s, object, orig_size);
init_object(s, object, SLUB_RED_ACTIVE);
return true;
bad:
if (folio_test_slab(slab_folio(slab))) {
/*
* 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");
slab->inuse = slab->objects;
slab->freelist = NULL;
}
return false;
}
static inline int free_consistency_checks(struct kmem_cache *s,
struct slab *slab, void *object, unsigned long addr)
{
if (!check_valid_pointer(s, slab, object)) {
slab_err(s, slab, "Invalid object pointer 0x%p", object);
return 0;
}
if (on_freelist(s, slab, object)) {
object_err(s, slab, object, "Object already free");
return 0;
}
if (!check_object(s, slab, object, SLUB_RED_ACTIVE))
return 0;
if (unlikely(s != slab->slab_cache)) {
if (!folio_test_slab(slab_folio(slab))) {
slab_err(s, slab, "Attempt to free object(0x%p) outside of slab",
object);
} else if (!slab->slab_cache) {
pr_err("SLUB <none>: no slab for object 0x%p.\n",
object);
dump_stack();
} else
object_err(s, slab, object,
"page slab pointer corrupt.");
return 0;
}
return 1;
}
/*
* Parse a block of slab_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("slab_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;
slab_flags_t global_flags;
char *saved_str;
char *slab_list;
bool global_slub_debug_changed = false;
bool slab_list_specified = false;
global_flags = 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) {
global_flags = flags;
global_slub_debug_changed = true;
} else {
slab_list_specified = true;
if (flags & SLAB_STORE_USER)
stack_depot_request_early_init();
}
}
/*
* For backwards compatibility, a single list of flags with list of
* slabs means debugging is only changed for those slabs, so the global
* slab_debug should be unchanged (0 or DEBUG_DEFAULT_FLAGS, depending
* on CONFIG_SLUB_DEBUG_ON). 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)
global_flags = slub_debug;
slub_debug_string = saved_str;
}
out:
slub_debug = global_flags;
if (slub_debug & SLAB_STORE_USER)
stack_depot_request_early_init();
if (slub_debug != 0 || slub_debug_string)
static_branch_enable(&slub_debug_enabled);
else
static_branch_disable(&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("slab_debug", setup_slub_debug);
__setup_param("slub_debug", slub_debug, setup_slub_debug, 0);
/*
* kmem_cache_flags - apply debugging options to the cache
* @flags: flags to set
* @name: name of the cache
*
* Debug option(s) are applied to @flags. In addition to the debug
* option(s), if a slab name (or multiple) is specified i.e.
* slab_debug=<Debug-Options>,<slab name1>,<slab name2> ...
* then only the select slabs will receive the debug option(s).
*/
slab_flags_t kmem_cache_flags(slab_flags_t flags, const char *name)
{
char *iter;
size_t len;
char *next_block;
slab_flags_t block_flags;
slab_flags_t slub_debug_local = slub_debug;
if (flags & SLAB_NO_USER_FLAGS)
return flags;
/*
* If the slab cache is for debugging (e.g. kmemleak) then
* don't store user (stack trace) information by default,
* but let the user enable it via the command line below.
*/
if (flags & SLAB_NOLEAKTRACE)
slub_debug_local &= ~SLAB_STORE_USER;
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_local;
}
#else /* !CONFIG_SLUB_DEBUG */
static inline void setup_object_debug(struct kmem_cache *s, void *object) {}
static inline
void setup_slab_debug(struct kmem_cache *s, struct slab *slab, void *addr) {}
static inline bool alloc_debug_processing(struct kmem_cache *s,
struct slab *slab, void *object, int orig_size) { return true; }
static inline bool free_debug_processing(struct kmem_cache *s,
struct slab *slab, void *head, void *tail, int *bulk_cnt,
unsigned long addr, depot_stack_handle_t handle) { return true; }
static inline void slab_pad_check(struct kmem_cache *s, struct slab *slab) {}
static inline int check_object(struct kmem_cache *s, struct slab *slab,
void *object, u8 val) { return 1; }
static inline depot_stack_handle_t set_track_prepare(void) { return 0; }
static inline void set_track(struct kmem_cache *s, void *object,
enum track_item alloc, unsigned long addr) {}
static inline void add_full(struct kmem_cache *s, struct kmem_cache_node *n,
struct slab *slab) {}
static inline void remove_full(struct kmem_cache *s, struct kmem_cache_node *n,
struct slab *slab) {}
slab_flags_t kmem_cache_flags(slab_flags_t flags, const char *name)
{
return flags;
}
#define slub_debug 0
#define disable_higher_order_debug 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) {}
#ifndef CONFIG_SLUB_TINY
static bool freelist_corrupted(struct kmem_cache *s, struct slab *slab,
void **freelist, void *nextfree)
{
return false;
}
#endif
#endif /* CONFIG_SLUB_DEBUG */
static inline enum node_stat_item cache_vmstat_idx(struct kmem_cache *s)
{
return (s->flags & SLAB_RECLAIM_ACCOUNT) ?
NR_SLAB_RECLAIMABLE_B : NR_SLAB_UNRECLAIMABLE_B;
}
#ifdef CONFIG_MEMCG_KMEM
static inline void memcg_free_slab_cgroups(struct slab *slab)
{
kfree(slab_objcgs(slab));
slab->memcg_data = 0;
}
static inline size_t obj_full_size(struct kmem_cache *s)
{
/*
* For each accounted object there is an extra space which is used
* to store obj_cgroup membership. Charge it too.
*/
return s->size + sizeof(struct obj_cgroup *);
}
/*
* Returns false if the allocation should fail.
*/
static bool __memcg_slab_pre_alloc_hook(struct kmem_cache *s,
struct list_lru *lru,
struct obj_cgroup **objcgp,
size_t objects, gfp_t flags)
{
/*
* The obtained objcg pointer is safe to use within the current scope,
* defined by current task or set_active_memcg() pair.
* obj_cgroup_get() is used to get a permanent reference.
*/
struct obj_cgroup *objcg = current_obj_cgroup();
if (!objcg)
return true;
if (lru) {
int ret;
struct mem_cgroup *memcg;
memcg = get_mem_cgroup_from_objcg(objcg);
ret = memcg_list_lru_alloc(memcg, lru, flags);
css_put(&memcg->css);
if (ret)
return false;
}
if (obj_cgroup_charge(objcg, flags, objects * obj_full_size(s)))
return false;
*objcgp = objcg;
return true;
}
/*
* Returns false if the allocation should fail.
*/
static __fastpath_inline
bool memcg_slab_pre_alloc_hook(struct kmem_cache *s, struct list_lru *lru,
struct obj_cgroup **objcgp, size_t objects,
gfp_t flags)
{
if (!memcg_kmem_online())
return true;
if (likely(!(flags & __GFP_ACCOUNT) && !(s->flags & SLAB_ACCOUNT)))
return true;
return likely(__memcg_slab_pre_alloc_hook(s, lru, objcgp, objects,
flags));
}
static void __memcg_slab_post_alloc_hook(struct kmem_cache *s,
struct obj_cgroup *objcg,
gfp_t flags, size_t size,
void **p)
{
struct slab *slab;
unsigned long off;
size_t i;
flags &= gfp_allowed_mask;
for (i = 0; i < size; i++) {
if (likely(p[i])) {
slab = virt_to_slab(p[i]);
if (!slab_objcgs(slab) &&
memcg_alloc_slab_cgroups(slab, s, flags, false)) {
obj_cgroup_uncharge(objcg, obj_full_size(s));
continue;
}
off = obj_to_index(s, slab, p[i]);
obj_cgroup_get(objcg);
slab_objcgs(slab)[off] = objcg;
mod_objcg_state(objcg, slab_pgdat(slab),
cache_vmstat_idx(s), obj_full_size(s));
} else {
obj_cgroup_uncharge(objcg, obj_full_size(s));
}
}
}
static __fastpath_inline
void memcg_slab_post_alloc_hook(struct kmem_cache *s, struct obj_cgroup *objcg,
gfp_t flags, size_t size, void **p)
{
if (likely(!memcg_kmem_online() || !objcg))
return;
return __memcg_slab_post_alloc_hook(s, objcg, flags, size, p);
}
static void __memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab,
void **p, int objects,
struct obj_cgroup **objcgs)
{
for (int i = 0; i < objects; i++) {
struct obj_cgroup *objcg;
unsigned int off;
off = obj_to_index(s, slab, p[i]);
objcg = objcgs[off];
if (!objcg)
continue;
objcgs[off] = NULL;
obj_cgroup_uncharge(objcg, obj_full_size(s));
mod_objcg_state(objcg, slab_pgdat(slab), cache_vmstat_idx(s),
-obj_full_size(s));
obj_cgroup_put(objcg);
}
}
static __fastpath_inline
void memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab, void **p,
int objects)
{
struct obj_cgroup **objcgs;
if (!memcg_kmem_online())
return;
objcgs = slab_objcgs(slab);
if (likely(!objcgs))
return;
__memcg_slab_free_hook(s, slab, p, objects, objcgs);
}
static inline
void memcg_slab_alloc_error_hook(struct kmem_cache *s, int objects,
struct obj_cgroup *objcg)
{
if (objcg)
obj_cgroup_uncharge(objcg, objects * obj_full_size(s));
}
#else /* CONFIG_MEMCG_KMEM */
static inline void memcg_free_slab_cgroups(struct slab *slab)
{
}
static inline bool memcg_slab_pre_alloc_hook(struct kmem_cache *s,
struct list_lru *lru,
struct obj_cgroup **objcgp,
size_t objects, gfp_t flags)
{
return true;
}
static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s,
struct obj_cgroup *objcg,
gfp_t flags, size_t size,
void **p)
{
}
static inline void memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab,
void **p, int objects)
{
}
static inline
void memcg_slab_alloc_error_hook(struct kmem_cache *s, int objects,
struct obj_cgroup *objcg)
{
}
#endif /* CONFIG_MEMCG_KMEM */
/*
* Hooks for other subsystems that check memory allocations. In a typical
* production configuration these hooks all should produce no code at all.
*
* Returns true if freeing of the object can proceed, false if its reuse
* was delayed by KASAN quarantine, or it was returned to KFENCE.
*/
static __always_inline
bool slab_free_hook(struct kmem_cache *s, void *x, bool init)
{
kmemleak_free_recursive(x, s->flags);
kmsan_slab_free(s, x);
debug_check_no_locks_freed(x, s->object_size);
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);
if (kfence_free(x))
return false;
/*
* As memory initialization might be integrated into KASAN,
* kasan_slab_free and initialization memset's must be
* kept together to avoid discrepancies in behavior.
*
* The initialization memset's clear the object and the metadata,
* but don't touch the SLAB redzone.
*/
if (unlikely(init)) {
int rsize;
if (!kasan_has_integrated_init())
memset(kasan_reset_tag(x), 0, s->object_size);
rsize = (s->flags & SLAB_RED_ZONE) ? s->red_left_pad : 0;
memset((char *)kasan_reset_tag(x) + s->inuse, 0,
s->size - s->inuse - rsize);
}
/* KASAN might put x into memory quarantine, delaying its reuse. */
return !kasan_slab_free(s, x, init);
}
static inline bool slab_free_freelist_hook(struct kmem_cache *s,
void **head, void **tail,
int *cnt)
{
void *object;
void *next = *head;
void *old_tail = *tail;
bool init;
if (is_kfence_address(next)) {
slab_free_hook(s, next, false);
return false;
}
/* Head and tail of the reconstructed freelist */
*head = NULL;
*tail = NULL;
init = slab_want_init_on_free(s);
do {
object = next;
next = get_freepointer(s, object);
/* If object's reuse doesn't have to be delayed */
if (likely(slab_free_hook(s, object, init))) {
/* Move object to the new freelist */
set_freepointer(s, object, *head);
*head = object;
if (!*tail)
*tail = object;
} else {
/*
* Adjust the reconstructed freelist depth
* accordingly if object's reuse is delayed.
*/
--(*cnt);
}
} while (object != old_tail);
return *head != NULL;
}
static void *setup_object(struct kmem_cache *s, void *object)
{
setup_object_debug(s, object);
object = kasan_init_slab_obj(s, object);
if (unlikely(s->ctor)) {
kasan_unpoison_new_object(s, object);
s->ctor(object);
kasan_poison_new_object(s, object);
}
return object;
}
/*
* Slab allocation and freeing
*/
static inline struct slab *alloc_slab_page(gfp_t flags, int node,
struct kmem_cache_order_objects oo)
{
struct folio *folio;
struct slab *slab;
unsigned int order = oo_order(oo);
folio = (struct folio *)alloc_pages_node(node, flags, order);
if (!folio)
return NULL;
slab = folio_slab(folio);
__folio_set_slab(folio);
/* Make the flag visible before any changes to folio->mapping */
smp_wmb();
if (folio_is_pfmemalloc(folio))
slab_set_pfmemalloc(slab);
return slab;
}
#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,
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 slab *slab)
{
void *start;
void *cur;
void *next;
unsigned long idx, pos, page_limit, freelist_count;
if (slab->objects < 2 || !s->random_seq)
return false;
freelist_count = oo_objects(s->oo);
pos = get_random_u32_below(freelist_count);
page_limit = slab->objects * s->size;
start = fixup_red_left(s, slab_address(slab));
/* First entry is used as the base of the freelist */
cur = next_freelist_entry(s, &pos, start, page_limit, freelist_count);
cur = setup_object(s, cur);
slab->freelist = cur;
for (idx = 1; idx < slab->objects; idx++) {
next = next_freelist_entry(s, &pos, start, page_limit,
freelist_count);
next = setup_object(s, 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 slab *slab)
{
return false;
}
#endif /* CONFIG_SLAB_FREELIST_RANDOM */
static __always_inline void account_slab(struct slab *slab, int order,
struct kmem_cache *s, gfp_t gfp)
{
if (memcg_kmem_online() && (s->flags & SLAB_ACCOUNT))
memcg_alloc_slab_cgroups(slab, s, gfp, true);
mod_node_page_state(slab_pgdat(slab), cache_vmstat_idx(s),
PAGE_SIZE << order);
}
static __always_inline void unaccount_slab(struct slab *slab, int order,
struct kmem_cache *s)
{
if (memcg_kmem_online())
memcg_free_slab_cgroups(slab);
mod_node_page_state(slab_pgdat(slab), cache_vmstat_idx(s),
-(PAGE_SIZE << order));
}
static struct slab *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
{
struct slab *slab;
struct kmem_cache_order_objects oo = s->oo;
gfp_t alloc_gfp;
void *start, *p, *next;
int idx;
bool shuffle;
flags &= gfp_allowed_mask;
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;
slab = alloc_slab_page(alloc_gfp, node, oo);
if (unlikely(!slab)) {
oo = s->min;
alloc_gfp = flags;
/*
* Allocation may have failed due to fragmentation.
* Try a lower order alloc if possible
*/
slab = alloc_slab_page(alloc_gfp, node, oo);
if (unlikely(!slab))
return NULL;
stat(s, ORDER_FALLBACK);
}
slab->objects = oo_objects(oo);
slab->inuse = 0;
slab->frozen = 0;
account_slab(slab, oo_order(oo), s, flags);
slab->slab_cache = s;
kasan_poison_slab(slab);
start = slab_address(slab);
setup_slab_debug(s, slab, start);
shuffle = shuffle_freelist(s, slab);
if (!shuffle) {
start = fixup_red_left(s, start);
start = setup_object(s, start);
slab->freelist = start;
for (idx = 0, p = start; idx < slab->objects - 1; idx++) {
next = p + s->size;
next = setup_object(s, next);
set_freepointer(s, p, next);
p = next;
}
set_freepointer(s, p, NULL);
}
return slab;
}
static struct slab *new_slab(struct kmem_cache *s, gfp_t flags, int node)
{
if (unlikely(flags & GFP_SLAB_BUG_MASK))
flags = kmalloc_fix_flags(flags);
WARN_ON_ONCE(s->ctor && (flags & __GFP_ZERO));
return allocate_slab(s,
flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
}
static void __free_slab(struct kmem_cache *s, struct slab *slab)
{
struct folio *folio = slab_folio(slab);
int order = folio_order(folio);
int pages = 1 << order;
__slab_clear_pfmemalloc(slab);
folio->mapping = NULL;
/* Make the mapping reset visible before clearing the flag */
smp_wmb();
__folio_clear_slab(folio);
mm_account_reclaimed_pages(pages);
unaccount_slab(slab, order, s);
__free_pages(&folio->page, order);
}
static void rcu_free_slab(struct rcu_head *h)
{
struct slab *slab = container_of(h, struct slab, rcu_head);
__free_slab(slab->slab_cache, slab);
}
static void free_slab(struct kmem_cache *s, struct slab *slab)
{
if (kmem_cache_debug_flags(s, SLAB_CONSISTENCY_CHECKS)) {
void *p;
slab_pad_check(s, slab);
for_each_object(p, s, slab_address(slab), slab->objects)
check_object(s, slab, p, SLUB_RED_INACTIVE);
}
if (unlikely(s->flags & SLAB_TYPESAFE_BY_RCU))
call_rcu(&slab->rcu_head, rcu_free_slab);
else
__free_slab(s, slab);
}
static void discard_slab(struct kmem_cache *s, struct slab *slab)
{
dec_slabs_node(s, slab_nid(slab), slab->objects);
free_slab(s, slab);
}
/*
* SLUB reuses PG_workingset bit to keep track of whether it's on
* the per-node partial list.
*/
static inline bool slab_test_node_partial(const struct slab *slab)
{
return folio_test_workingset((struct folio *)slab_folio(slab));
}
static inline void slab_set_node_partial(struct slab *slab)
{
set_bit(PG_workingset, folio_flags(slab_folio(slab), 0));
}
static inline void slab_clear_node_partial(struct slab *slab)
{
clear_bit(PG_workingset, folio_flags(slab_folio(slab), 0));
}
/*
* Management of partially allocated slabs.
*/
static inline void
__add_partial(struct kmem_cache_node *n, struct slab *slab, int tail)
{
n->nr_partial++;
if (tail == DEACTIVATE_TO_TAIL)
list_add_tail(&slab->slab_list, &n->partial);
else
list_add(&slab->slab_list, &n->partial);
slab_set_node_partial(slab);
}
static inline void add_partial(struct kmem_cache_node *n,
struct slab *slab, int tail)
{
lockdep_assert_held(&n->list_lock);
__add_partial(n, slab, tail);
}
static inline void remove_partial(struct kmem_cache_node *n,
struct slab *slab)
{
lockdep_assert_held(&n->list_lock);
list_del(&slab->slab_list);
slab_clear_node_partial(slab);
n->nr_partial--;
}
/*
* Called only for kmem_cache_debug() caches instead of remove_partial(), with a
* slab from the n->partial list. Remove only a single object from the slab, do
* the alloc_debug_processing() checks and leave the slab on the list, or move
* it to full list if it was the last free object.
*/
static void *alloc_single_from_partial(struct kmem_cache *s,
struct kmem_cache_node *n, struct slab *slab, int orig_size)
{
void *object;
lockdep_assert_held(&n->list_lock);
object = slab->freelist;
slab->freelist = get_freepointer(s, object);
slab->inuse++;
if (!alloc_debug_processing(s, slab, object, orig_size)) {
remove_partial(n, slab);
return NULL;
}
if (slab->inuse == slab->objects) {
remove_partial(n, slab);
add_full(s, n, slab);
}
return object;
}
/*
* Called only for kmem_cache_debug() caches to allocate from a freshly
* allocated slab. Allocate a single object instead of whole freelist
* and put the slab to the partial (or full) list.
*/
static void *alloc_single_from_new_slab(struct kmem_cache *s,
struct slab *slab, int orig_size)
{
int nid = slab_nid(slab);
struct kmem_cache_node *n = get_node(s, nid);
unsigned long flags;
void *object;
object = slab->freelist;
slab->freelist = get_freepointer(s, object);
slab->inuse = 1;
if (!alloc_debug_processing(s, slab, object, orig_size))
/*
* It's not really expected that this would fail on a
* freshly allocated slab, but a concurrent memory
* corruption in theory could cause that.
*/
return NULL;
spin_lock_irqsave(&n->list_lock, flags);
if (slab->inuse == slab->objects)
add_full(s, n, slab);
else
add_partial(n, slab, DEACTIVATE_TO_HEAD);
inc_slabs_node(s, nid, slab->objects);
spin_unlock_irqrestore(&n->list_lock, flags);
return object;
}
#ifdef CONFIG_SLUB_CPU_PARTIAL
static void put_cpu_partial(struct kmem_cache *s, struct slab *slab, int drain);
#else
static inline void put_cpu_partial(struct kmem_cache *s, struct slab *slab,
int drain) { }
#endif
static inline bool pfmemalloc_match(struct slab *slab, gfp_t gfpflags);
/*
* Try to allocate a partial slab from a specific node.
*/
static struct slab *get_partial_node(struct kmem_cache *s,
struct kmem_cache_node *n,
struct partial_context *pc)
{
struct slab *slab, *slab2, *partial = NULL;
unsigned long flags;
unsigned int partial_slabs = 0;
/*
* 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_partial()
* will return NULL.
*/
if (!n || !n->nr_partial)
return NULL;
spin_lock_irqsave(&n->list_lock, flags);
list_for_each_entry_safe(slab, slab2, &n->partial, slab_list) {
if (!pfmemalloc_match(slab, pc->flags))
continue;
if (IS_ENABLED(CONFIG_SLUB_TINY) || kmem_cache_debug(s)) {
void *object = alloc_single_from_partial(s, n, slab,
pc->orig_size);
if (object) {
partial = slab;
pc->object = object;
break;
}
continue;
}
remove_partial(n, slab);
if (!partial) {
partial = slab;
stat(s, ALLOC_FROM_PARTIAL);
} else {
put_cpu_partial(s, slab, 0);
stat(s, CPU_PARTIAL_NODE);
partial_slabs++;
}
#ifdef CONFIG_SLUB_CPU_PARTIAL
if (!kmem_cache_has_cpu_partial(s)
|| partial_slabs > s->cpu_partial_slabs / 2)
break;
#else
break;
#endif
}
spin_unlock_irqrestore(&n->list_lock, flags);
return partial;
}
/*
* Get a slab from somewhere. Search in increasing NUMA distances.
*/
static struct slab *get_any_partial(struct kmem_cache *s,
struct partial_context *pc)
{
#ifdef CONFIG_NUMA
struct zonelist *zonelist;
struct zoneref *z;
struct zone *zone;
enum zone_type highest_zoneidx = gfp_zone(pc->flags);
struct slab *slab;
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(), pc->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, pc->flags) &&
n->nr_partial > s->min_partial) {
slab = get_partial_node(s, n, pc);
if (slab) {
/*
* 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 slab;
}
}
}
} while (read_mems_allowed_retry(cpuset_mems_cookie));
#endif /* CONFIG_NUMA */
return NULL;
}
/*
* Get a partial slab, lock it and return it.
*/
static struct slab *get_partial(struct kmem_cache *s, int node,
struct partial_context *pc)
{
struct slab *slab;
int searchnode = node;
if (node == NUMA_NO_NODE)
searchnode = numa_mem_id();
slab = get_partial_node(s, get_node(s, searchnode), pc);
if (slab || node != NUMA_NO_NODE)
return slab;
return get_any_partial(s, pc);
}
#ifndef CONFIG_SLUB_TINY
#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 /* CONFIG_PREEMPTION */
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;
struct kmem_cache_cpu *c;
for_each_possible_cpu(cpu) {
c = per_cpu_ptr(s->cpu_slab, cpu);
local_lock_init(&c->lock);
c->tid = init_tid(cpu);
}
}
/*
* Finishes removing the cpu slab. Merges cpu's freelist with slab's freelist,
* unfreezes the slabs and puts it on the proper list.
* Assumes the slab has been already safely taken away from kmem_cache_cpu
* by the caller.
*/
static void deactivate_slab(struct kmem_cache *s, struct slab *slab,
void *freelist)
{
struct kmem_cache_node *n = get_node(s, slab_nid(slab));
int free_delta = 0;
void *nextfree, *freelist_iter, *freelist_tail;
int tail = DEACTIVATE_TO_HEAD;
unsigned long flags = 0;
struct slab new;
struct slab old;
if (slab->freelist) {
stat(s, DEACTIVATE_REMOTE_FREES);
tail = DEACTIVATE_TO_TAIL;
}
/*
* Stage one: Count the objects on cpu's freelist as free_delta and
* remember the last object in freelist_tail for later splicing.
*/
freelist_tail = NULL;
freelist_iter = freelist;
while (freelist_iter) {
nextfree = get_freepointer(s, freelist_iter);
/*
* If 'nextfree' is invalid, it is possible that the object at
* 'freelist_iter' is already corrupted. So isolate all objects
* starting at 'freelist_iter' by skipping them.
*/
if (freelist_corrupted(s, slab, &freelist_iter, nextfree))
break;
freelist_tail = freelist_iter;
free_delta++;
freelist_iter = nextfree;
}
/*
* Stage two: Unfreeze the slab while splicing the per-cpu
* freelist to the head of slab's freelist.
*/
do {
old.freelist = READ_ONCE(slab->freelist);
old.counters = READ_ONCE(slab->counters);
VM_BUG_ON(!old.frozen);
/* Determine target state of the slab */
new.counters = old.counters;
new.frozen = 0;
if (freelist_tail) {
new.inuse -= free_delta;
set_freepointer(s, freelist_tail, old.freelist);
new.freelist = freelist;
} else {
new.freelist = old.freelist;
}
} while (!slab_update_freelist(s, slab,
old.freelist, old.counters,
new.freelist, new.counters,
"unfreezing slab"));
/*
* Stage three: Manipulate the slab list based on the updated state.
*/
if (!new.inuse && n->nr_partial >= s->min_partial) {
stat(s, DEACTIVATE_EMPTY);
discard_slab(s, slab);
stat(s, FREE_SLAB);
} else if (new.freelist) {
spin_lock_irqsave(&n->list_lock, flags);
add_partial(n, slab, tail);
spin_unlock_irqrestore(&n->list_lock, flags);
stat(s, tail);
} else {
stat(s, DEACTIVATE_FULL);
}
}
#ifdef CONFIG_SLUB_CPU_PARTIAL
static void __put_partials(struct kmem_cache *s, struct slab *partial_slab)
{
struct kmem_cache_node *n = NULL, *n2 = NULL;
struct slab *slab, *slab_to_discard = NULL;
unsigned long flags = 0;
while (partial_slab) {
slab = partial_slab;
partial_slab = slab->next;
n2 = get_node(s, slab_nid(slab));
if (n != n2) {
if (n)
spin_unlock_irqrestore(&n->list_lock, flags);
n = n2;
spin_lock_irqsave(&n->list_lock, flags);
}
if (unlikely(!slab->inuse && n->nr_partial >= s->min_partial)) {
slab->next = slab_to_discard;
slab_to_discard = slab;
} else {
add_partial(n, slab, DEACTIVATE_TO_TAIL);
stat(s, FREE_ADD_PARTIAL);
}
}
if (n)
spin_unlock_irqrestore(&n->list_lock, flags);
while (slab_to_discard) {
slab = slab_to_discard;
slab_to_discard = slab_to_discard->next;
stat(s, DEACTIVATE_EMPTY);
discard_slab(s, slab);
stat(s, FREE_SLAB);
}
}
/*
* Put all the cpu partial slabs to the node partial list.
*/
static void put_partials(struct kmem_cache *s)
{
struct slab *partial_slab;
unsigned long flags;
local_lock_irqsave(&s->cpu_slab->lock, flags);
partial_slab = this_cpu_read(s->cpu_slab->partial);
this_cpu_write(s->cpu_slab->partial, NULL);
local_unlock_irqrestore(&s->cpu_slab->lock, flags);
if (partial_slab)
__put_partials(s, partial_slab);
}
static void put_partials_cpu(struct kmem_cache *s,
struct kmem_cache_cpu *c)
{
struct slab *partial_slab;
partial_slab = slub_percpu_partial(c);
c->partial = NULL;
if (partial_slab)
__put_partials(s, partial_slab);
}
/*
* Put a slab into a partial slab 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 slab *slab, int drain)
{
struct slab *oldslab;
struct slab *slab_to_put = NULL;
unsigned long flags;
int slabs = 0;
local_lock_irqsave(&s->cpu_slab->lock, flags);
oldslab = this_cpu_read(s->cpu_slab->partial);
if (oldslab) {
if (drain && oldslab->slabs >= s->cpu_partial_slabs) {
/*
* Partial array is full. Move the existing set to the
* per node partial list. Postpone the actual unfreezing
* outside of the critical section.
*/
slab_to_put = oldslab;
oldslab = NULL;
} else {
slabs = oldslab->slabs;
}
}
slabs++;
slab->slabs = slabs;
slab->next = oldslab;
this_cpu_write(s->cpu_slab->partial, slab);
local_unlock_irqrestore(&s->cpu_slab->lock, flags);
if (slab_to_put) {
__put_partials(s, slab_to_put);
stat(s, CPU_PARTIAL_DRAIN);
}
}
#else /* CONFIG_SLUB_CPU_PARTIAL */
static inline void put_partials(struct kmem_cache *s) { }
static inline void put_partials_cpu(struct kmem_cache *s,
struct kmem_cache_cpu *c) { }
#endif /* CONFIG_SLUB_CPU_PARTIAL */
static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
{
unsigned long flags;
struct slab *slab;
void *freelist;
local_lock_irqsave(&s->cpu_slab->lock, flags);
slab = c->slab;
freelist = c->freelist;
c->slab = NULL;
c->freelist = NULL;
c->tid = next_tid(c->tid);
local_unlock_irqrestore(&s->cpu_slab->lock, flags);
if (slab) {
deactivate_slab(s, slab, freelist);
stat(s, CPUSLAB_FLUSH);
}
}
static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu)
{
struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
void *freelist = c->freelist;
struct slab *slab = c->slab;
c->slab = NULL;
c->freelist = NULL;
c->tid = next_tid(c->tid);
if (slab) {
deactivate_slab(s, slab, freelist);
stat(s, CPUSLAB_FLUSH);
}
put_partials_cpu(s, c);
}
struct slub_flush_work {
struct work_struct work;
struct kmem_cache *s;
bool skip;
};
/*
* Flush cpu slab.
*
* Called from CPU work handler with migration disabled.
*/
static void flush_cpu_slab(struct work_struct *w)
{
struct kmem_cache *s;
struct kmem_cache_cpu *c;
struct slub_flush_work *sfw;
sfw = container_of(w, struct slub_flush_work, work);
s = sfw->s;
c = this_cpu_ptr(s->cpu_slab);
if (c->slab)
flush_slab(s, c);
put_partials(s);
}
static bool has_cpu_slab(int cpu, struct kmem_cache *s)
{
struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
return c->slab || slub_percpu_partial(c);
}
static DEFINE_MUTEX(flush_lock);
static DEFINE_PER_CPU(struct slub_flush_work, slub_flush);
static void flush_all_cpus_locked(struct kmem_cache *s)
{
struct slub_flush_work *sfw;
unsigned int cpu;
lockdep_assert_cpus_held();
mutex_lock(&flush_lock);
for_each_online_cpu(cpu) {
sfw = &per_cpu(slub_flush, cpu);
if (!has_cpu_slab(cpu, s)) {
sfw->skip = true;
continue;
}
INIT_WORK(&sfw->work, flush_cpu_slab);
sfw->skip = false;
sfw->s = s;
queue_work_on(cpu, flushwq, &sfw->work);
}
for_each_online_cpu(cpu) {
sfw = &per_cpu(slub_flush, cpu);
if (sfw->skip)
continue;
flush_work(&sfw->work);
}
mutex_unlock(&flush_lock);
}
static void flush_all(struct kmem_cache *s)
{
cpus_read_lock();
flush_all_cpus_locked(s);
cpus_read_unlock();
}
/*
* 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;
mutex_lock(&slab_mutex);
list_for_each_entry(s, &slab_caches, list)
__flush_cpu_slab(s, cpu);
mutex_unlock(&slab_mutex);
return 0;
}
#else /* CONFIG_SLUB_TINY */
static inline void flush_all_cpus_locked(struct kmem_cache *s) { }
static inline void flush_all(struct kmem_cache *s) { }
static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) { }
static inline int slub_cpu_dead(unsigned int cpu) { return 0; }
#endif /* CONFIG_SLUB_TINY */
/*
* Check if the objects in a per cpu structure fit numa
* locality expectations.
*/
static inline int node_match(struct slab *slab, int node)
{
#ifdef CONFIG_NUMA
if (node != NUMA_NO_NODE && slab_nid(slab) != node)
return 0;
#endif
return 1;
}
#ifdef CONFIG_SLUB_DEBUG
static int count_free(struct slab *slab)
{
return slab->objects - slab->inuse;
}
static inline unsigned long node_nr_objs(struct kmem_cache_node *n)
{
return atomic_long_read(&n->total_objects);
}
/* Supports checking bulk free of a constructed freelist */
static inline bool free_debug_processing(struct kmem_cache *s,
struct slab *slab, void *head, void *tail, int *bulk_cnt,
unsigned long addr, depot_stack_handle_t handle)
{
bool checks_ok = false;
void *object = head;
int cnt = 0;
if (s->flags & SLAB_CONSISTENCY_CHECKS) {
if (!check_slab(s, slab))
goto out;
}
if (slab->inuse < *bulk_cnt) {
slab_err(s, slab, "Slab has %d allocated objects but %d are to be freed\n",
slab->inuse, *bulk_cnt);
goto out;
}
next_object:
if (++cnt > *bulk_cnt)
goto out_cnt;
if (s->flags & SLAB_CONSISTENCY_CHECKS) {
if (!free_consistency_checks(s, slab, object, addr))
goto out;
}
if (s->flags & SLAB_STORE_USER)
set_track_update(s, object, TRACK_FREE, addr, handle);
trace(s, slab, 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;
}
checks_ok = true;
out_cnt:
if (cnt != *bulk_cnt) {
slab_err(s, slab, "Bulk free expected %d objects but found %d\n",
*bulk_cnt, cnt);
*bulk_cnt = cnt;
}
out:
if (!checks_ok)
slab_fix(s, "Object at 0x%p not freed", object);
return checks_ok;
}
#endif /* CONFIG_SLUB_DEBUG */
#if defined(CONFIG_SLUB_DEBUG) || defined(SLAB_SUPPORTS_SYSFS)
static unsigned long count_partial(struct kmem_cache_node *n,
int (*get_count)(struct slab *))
{
unsigned long flags;
unsigned long x = 0;
struct slab *slab;
spin_lock_irqsave(&n->list_lock, flags);
list_for_each_entry(slab, &n->partial, slab_list)
x += get_count(slab);
spin_unlock_irqrestore(&n->list_lock, flags);
return x;
}
#endif /* CONFIG_SLUB_DEBUG || SLAB_SUPPORTS_SYSFS */
#ifdef CONFIG_SLUB_DEBUG
static noinline void
slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid)
{
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 slab_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);
}
}
#else /* CONFIG_SLUB_DEBUG */
static inline void
slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid) { }
#endif
static inline bool pfmemalloc_match(struct slab *slab, gfp_t gfpflags)
{
if (unlikely(slab_test_pfmemalloc(slab)))
return gfp_pfmemalloc_allowed(gfpflags);
return true;
}
#ifndef CONFIG_SLUB_TINY
static inline bool
__update_cpu_freelist_fast(struct kmem_cache *s,
void *freelist_old, void *freelist_new,
unsigned long tid)
{
freelist_aba_t old = { .freelist = freelist_old, .counter = tid };
freelist_aba_t new = { .freelist = freelist_new, .counter = next_tid(tid) };
return this_cpu_try_cmpxchg_freelist(s->cpu_slab->freelist_tid.full,
&old.full, new.full);
}
/*
* Check the slab->freelist and either transfer the freelist to the
* per cpu freelist or deactivate the slab.
*
* The slab is still frozen if the return value is not NULL.
*
* If this function returns NULL then the slab has been unfrozen.
*/
static inline void *get_freelist(struct kmem_cache *s, struct slab *slab)
{
struct slab new;
unsigned long counters;
void *freelist;
lockdep_assert_held(this_cpu_ptr(&s->cpu_slab->lock));
do {
freelist = slab->freelist;
counters = slab->counters;
new.counters = counters;
new.inuse = slab->objects;
new.frozen = freelist != NULL;
} while (!__slab_update_freelist(s, slab,
freelist, counters,
NULL, new.counters,
"get_freelist"));
return freelist;
}
/*
* Freeze the partial slab and return the pointer to the freelist.
*/
static inline void *freeze_slab(struct kmem_cache *s, struct slab *slab)
{
struct slab new;
unsigned long counters;
void *freelist;
do {
freelist = slab->freelist;
counters = slab->counters;
new.counters = counters;
VM_BUG_ON(new.frozen);
new.inuse = slab->objects;
new.frozen = 1;
} while (!slab_update_freelist(s, slab,
freelist, counters,
NULL, new.counters,
"freeze_slab"));
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 preemption is
* 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, unsigned int orig_size)
{
void *freelist;
struct slab *slab;
unsigned long flags;
struct partial_context pc;
stat(s, ALLOC_SLOWPATH);
reread_slab:
slab = READ_ONCE(c->slab);
if (!slab) {
/*
* if the node is not online or has no normal memory, just
* ignore the node constraint
*/
if (unlikely(node != NUMA_NO_NODE &&
!node_isset(node, slab_nodes)))
node = NUMA_NO_NODE;
goto new_slab;
}
if (unlikely(!node_match(slab, node))) {
/*
* same as above but node_match() being false already
* implies node != NUMA_NO_NODE
*/
if (!node_isset(node, slab_nodes)) {
node = NUMA_NO_NODE;
} else {
stat(s, ALLOC_NODE_MISMATCH);
goto deactivate_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(slab, gfpflags)))
goto deactivate_slab;
/* must check again c->slab in case we got preempted and it changed */
local_lock_irqsave(&s->cpu_slab->lock, flags);
if (unlikely(slab != c->slab)) {
local_unlock_irqrestore(&s->cpu_slab->lock, flags);
goto reread_slab;
}
freelist = c->freelist;
if (freelist)
goto load_freelist;
freelist = get_freelist(s, slab);
if (!freelist) {
c->slab = NULL;
c->tid = next_tid(c->tid);
local_unlock_irqrestore(&s->cpu_slab->lock, flags);
stat(s, DEACTIVATE_BYPASS);
goto new_slab;
}
stat(s, ALLOC_REFILL);
load_freelist:
lockdep_assert_held(this_cpu_ptr(&s->cpu_slab->lock));
/*
* freelist is pointing to the list of objects to be used.
* slab is pointing to the slab from which the objects are obtained.
* That slab must be frozen for per cpu allocations to work.
*/
VM_BUG_ON(!c->slab->frozen);
c->freelist = get_freepointer(s, freelist);
c->tid = next_tid(c->tid);
local_unlock_irqrestore(&s->cpu_slab->lock, flags);
return freelist;
deactivate_slab:
local_lock_irqsave(&s->cpu_slab->lock, flags);
if (slab != c->slab) {
local_unlock_irqrestore(&s->cpu_slab->lock, flags);
goto reread_slab;
}
freelist = c->freelist;
c->slab = NULL;
c->freelist = NULL;
c->tid = next_tid(c->tid);
local_unlock_irqrestore(&s->cpu_slab->lock, flags);
deactivate_slab(s, slab, freelist);
new_slab:
#ifdef CONFIG_SLUB_CPU_PARTIAL
while (slub_percpu_partial(c)) {
local_lock_irqsave(&s->cpu_slab->lock, flags);
if (unlikely(c->slab)) {
local_unlock_irqrestore(&s->cpu_slab->lock, flags);
goto reread_slab;
}
if (unlikely(!slub_percpu_partial(c))) {
local_unlock_irqrestore(&s->cpu_slab->lock, flags);
/* we were preempted and partial list got empty */
goto new_objects;
}
slab = slub_percpu_partial(c);
slub_set_percpu_partial(c, slab);
if (likely(node_match(slab, node) &&
pfmemalloc_match(slab, gfpflags))) {
c->slab = slab;
freelist = get_freelist(s, slab);
VM_BUG_ON(!freelist);
stat(s, CPU_PARTIAL_ALLOC);
goto load_freelist;
}
local_unlock_irqrestore(&s->cpu_slab->lock, flags);
slab->next = NULL;
__put_partials(s, slab);
}
#endif
new_objects:
pc.flags = gfpflags;
pc.orig_size = orig_size;
slab = get_partial(s, node, &pc);
if (slab) {
if (kmem_cache_debug(s)) {
freelist = pc.object;
/*
* For debug caches here we had to go through
* alloc_single_from_partial() so just store the
* tracking info and return the object.
*/
if (s->flags & SLAB_STORE_USER)
set_track(s, freelist, TRACK_ALLOC, addr);
return freelist;
}
freelist = freeze_slab(s, slab);
goto retry_load_slab;
}
slub_put_cpu_ptr(s->cpu_slab);
slab = new_slab(s, gfpflags, node);
c = slub_get_cpu_ptr(s->cpu_slab);
if (unlikely(!slab)) {
slab_out_of_memory(s, gfpflags, node);
return NULL;
}
stat(s, ALLOC_SLAB);
if (kmem_cache_debug(s)) {
freelist = alloc_single_from_new_slab(s, slab, orig_size);
if (unlikely(!freelist))
goto new_objects;
if (s->flags & SLAB_STORE_USER)
set_track(s, freelist, TRACK_ALLOC, addr);
return freelist;
}
/*
* No other reference to the slab yet so we can
* muck around with it freely without cmpxchg
*/
freelist = slab->freelist;
slab->freelist = NULL;
slab->inuse = slab->objects;
slab->frozen = 1;
inc_slabs_node(s, slab_nid(slab), slab->objects);
if (unlikely(!pfmemalloc_match(slab, gfpflags))) {
/*
* For !pfmemalloc_match() case we don't load freelist so that
* we don't make further mismatched allocations easier.
*/
deactivate_slab(s, slab, get_freepointer(s, freelist));
return freelist;
}
retry_load_slab:
local_lock_irqsave(&s->cpu_slab->lock, flags);
if (unlikely(c->slab)) {
void *flush_freelist = c->freelist;
struct slab *flush_slab = c->slab;
c->slab = NULL;
c->freelist = NULL;
c->tid = next_tid(c->tid);
local_unlock_irqrestore(&s->cpu_slab->lock, flags);
deactivate_slab(s, flush_slab, flush_freelist);
stat(s, CPUSLAB_FLUSH);
goto retry_load_slab;
}
c->slab = slab;
goto load_freelist;
}
/*
* A wrapper for ___slab_alloc() for contexts where preemption is not yet
* disabled. 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, unsigned int orig_size)
{
void *p;
#ifdef CONFIG_PREEMPT_COUNT
/*
* We may have been preempted and rescheduled on a different
* cpu before disabling preemption. Need to reload cpu area
* pointer.
*/
c = slub_get_cpu_ptr(s->cpu_slab);
#endif
p = ___slab_alloc(s, gfpflags, node, addr, c, orig_size);
#ifdef CONFIG_PREEMPT_COUNT
slub_put_cpu_ptr(s->cpu_slab);
#endif
return p;
}
static __always_inline void *__slab_alloc_node(struct kmem_cache *s,
gfp_t gfpflags, int node, unsigned long addr, size_t orig_size)
{
struct kmem_cache_cpu *c;
struct slab *slab;
unsigned long tid;
void *object;
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 must guarantee that tid and kmem_cache_cpu are retrieved on the
* same cpu. We read first the kmem_cache_cpu pointer and use it to read
* the tid. If we are preempted and switched to another cpu between the
* two reads, it's OK as the two are still associated with the same cpu
* and cmpxchg later will validate the cpu.
*/
c = raw_cpu_ptr(s->cpu_slab);
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 slab associated with previous tid
* won't be used with current tid. If we fetch tid first, object and
* slab 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;
slab = c->slab;
if (!USE_LOCKLESS_FAST_PATH() ||
unlikely(!object || !slab || !node_match(slab, node))) {
object = __slab_alloc(s, gfpflags, node, addr, c, orig_size);
} 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(!__update_cpu_freelist_fast(s, object, next_object, tid))) {
note_cmpxchg_failure("slab_alloc", s, tid);
goto redo;
}
prefetch_freepointer(s, next_object);
stat(s, ALLOC_FASTPATH);
}
return object;
}
#else /* CONFIG_SLUB_TINY */
static void *__slab_alloc_node(struct kmem_cache *s,
gfp_t gfpflags, int node, unsigned long addr, size_t orig_size)
{
struct partial_context pc;
struct slab *slab;
void *object;
pc.flags = gfpflags;
pc.orig_size = orig_size;
slab = get_partial(s, node, &pc);
if (slab)
return pc.object;
slab = new_slab(s, gfpflags, node);
if (unlikely(!slab)) {
slab_out_of_memory(s, gfpflags, node);
return NULL;
}
object = alloc_single_from_new_slab(s, slab, orig_size);
return object;
}
#endif /* CONFIG_SLUB_TINY */
/*
* 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 *)kasan_reset_tag(obj) + s->offset),
0, sizeof(void *));
}
noinline int should_failslab(struct kmem_cache *s, gfp_t gfpflags)
{
if (__should_failslab(s, gfpflags))
return -ENOMEM;
return 0;
}
ALLOW_ERROR_INJECTION(should_failslab, ERRNO);
static __fastpath_inline
struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s,
struct list_lru *lru,
struct obj_cgroup **objcgp,
size_t size, gfp_t flags)
{
flags &= gfp_allowed_mask;
might_alloc(flags);
if (unlikely(should_failslab(s, flags)))
return NULL;
if (unlikely(!memcg_slab_pre_alloc_hook(s, lru, objcgp, size, flags)))
return NULL;
return s;
}
static __fastpath_inline
void slab_post_alloc_hook(struct kmem_cache *s, struct obj_cgroup *objcg,
gfp_t flags, size_t size, void **p, bool init,
unsigned int orig_size)
{
unsigned int zero_size = s->object_size;
bool kasan_init = init;
size_t i;
gfp_t init_flags = flags & gfp_allowed_mask;
/*
* For kmalloc object, the allocated memory size(object_size) is likely
* larger than the requested size(orig_size). If redzone check is
* enabled for the extra space, don't zero it, as it will be redzoned
* soon. The redzone operation for this extra space could be seen as a
* replacement of current poisoning under certain debug option, and
* won't break other sanity checks.
*/
if (kmem_cache_debug_flags(s, SLAB_STORE_USER | SLAB_RED_ZONE) &&
(s->flags & SLAB_KMALLOC))
zero_size = orig_size;
/*
* When slab_debug is enabled, avoid memory initialization integrated
* into KASAN and instead zero out the memory via the memset below with
* the proper size. Otherwise, KASAN might overwrite SLUB redzones and
* cause false-positive reports. This does not lead to a performance
* penalty on production builds, as slab_debug is not intended to be
* enabled there.
*/
if (__slub_debug_enabled())
kasan_init = false;
/*
* As memory initialization might be integrated into KASAN,
* kasan_slab_alloc and initialization memset must be
* kept together to avoid discrepancies in behavior.
*
* As p[i] might get tagged, memset and kmemleak hook come after KASAN.
*/
for (i = 0; i < size; i++) {
p[i] = kasan_slab_alloc(s, p[i], init_flags, kasan_init);
if (p[i] && init && (!kasan_init ||
!kasan_has_integrated_init()))
memset(p[i], 0, zero_size);
kmemleak_alloc_recursive(p[i], s->object_size, 1,
s->flags, init_flags);
kmsan_slab_alloc(s, p[i], init_flags);
}
memcg_slab_post_alloc_hook(s, objcg, flags, size, p);
}
/*
* 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 __fastpath_inline void *slab_alloc_node(struct kmem_cache *s, struct list_lru *lru,
gfp_t gfpflags, int node, unsigned long addr, size_t orig_size)
{
void *object;
struct obj_cgroup *objcg = NULL;
bool init = false;
s = slab_pre_alloc_hook(s, lru, &objcg, 1, gfpflags);
if (unlikely(!s))
return NULL;
object = kfence_alloc(s, orig_size, gfpflags);
if (unlikely(object))
goto out;
object = __slab_alloc_node(s, gfpflags, node, addr, orig_size);
maybe_wipe_obj_freeptr(s, object);
init = slab_want_init_on_alloc(gfpflags, s);
out:
/*
* When init equals 'true', like for kzalloc() family, only
* @orig_size bytes might be zeroed instead of s->object_size
*/
slab_post_alloc_hook(s, objcg, gfpflags, 1, &object, init, orig_size);
return object;
}
void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags)
{
void *ret = slab_alloc_node(s, NULL, gfpflags, NUMA_NO_NODE, _RET_IP_,
s->object_size);
trace_kmem_cache_alloc(_RET_IP_, ret, s, gfpflags, NUMA_NO_NODE);
return ret;
}
EXPORT_SYMBOL(kmem_cache_alloc);
void *kmem_cache_alloc_lru(struct kmem_cache *s, struct list_lru *lru,
gfp_t gfpflags)
{
void *ret = slab_alloc_node(s, lru, gfpflags, NUMA_NO_NODE, _RET_IP_,
s->object_size);
trace_kmem_cache_alloc(_RET_IP_, ret, s, gfpflags, NUMA_NO_NODE);
return ret;
}
EXPORT_SYMBOL(kmem_cache_alloc_lru);
/**
* kmem_cache_alloc_node - Allocate an object on the specified node
* @s: The cache to allocate from.
* @gfpflags: See kmalloc().
* @node: node number of the target node.
*
* Identical to kmem_cache_alloc but it will allocate memory on the given
* node, which can improve the performance for cpu bound structures.
*
* Fallback to other node is possible if __GFP_THISNODE is not set.
*
* Return: pointer to the new object or %NULL in case of error
*/
void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node)
{
void *ret = slab_alloc_node(s, NULL, gfpflags, node, _RET_IP_, s->object_size);
trace_kmem_cache_alloc(_RET_IP_, ret, s, gfpflags, node);
return ret;
}
EXPORT_SYMBOL(kmem_cache_alloc_node);
/*
* To avoid unnecessary overhead, we pass through large allocation requests
* directly to the page allocator. We use __GFP_COMP, because we will need to
* know the allocation order to free the pages properly in kfree.
*/
static void *__kmalloc_large_node(size_t size, gfp_t flags, int node)
{
struct folio *folio;
void *ptr = NULL;
unsigned int order = get_order(size);
if (unlikely(flags & GFP_SLAB_BUG_MASK))
flags = kmalloc_fix_flags(flags);
flags |= __GFP_COMP;
folio = (struct folio *)alloc_pages_node(node, flags, order);
if (folio) {
ptr = folio_address(folio);
lruvec_stat_mod_folio(folio, NR_SLAB_UNRECLAIMABLE_B,
PAGE_SIZE << order);
}
ptr = kasan_kmalloc_large(ptr, size, flags);
/* As ptr might get tagged, call kmemleak hook after KASAN. */
kmemleak_alloc(ptr, size, 1, flags);
kmsan_kmalloc_large(ptr, size, flags);
return ptr;
}
void *kmalloc_large(size_t size, gfp_t flags)
{
void *ret = __kmalloc_large_node(size, flags, NUMA_NO_NODE);
trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << get_order(size),
flags, NUMA_NO_NODE);
return ret;
}
EXPORT_SYMBOL(kmalloc_large);
void *kmalloc_large_node(size_t size, gfp_t flags, int node)
{
void *ret = __kmalloc_large_node(size, flags, node);
trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << get_order(size),
flags, node);
return ret;
}
EXPORT_SYMBOL(kmalloc_large_node);
static __always_inline
void *__do_kmalloc_node(size_t size, gfp_t flags, int node,
unsigned long caller)
{
struct kmem_cache *s;
void *ret;
if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
ret = __kmalloc_large_node(size, flags, node);
trace_kmalloc(caller, ret, size,
PAGE_SIZE << get_order(size), flags, node);
return ret;
}
if (unlikely(!size))
return ZERO_SIZE_PTR;
s = kmalloc_slab(size, flags, caller);
ret = slab_alloc_node(s, NULL, flags, node, caller, size);
ret = kasan_kmalloc(s, ret, size, flags);
trace_kmalloc(caller, ret, size, s->size, flags, node);
return ret;
}
void *__kmalloc_node(size_t size, gfp_t flags, int node)
{
return __do_kmalloc_node(size, flags, node, _RET_IP_);
}
EXPORT_SYMBOL(__kmalloc_node);
void *__kmalloc(size_t size, gfp_t flags)
{
return __do_kmalloc_node(size, flags, NUMA_NO_NODE, _RET_IP_);
}
EXPORT_SYMBOL(__kmalloc);
void *__kmalloc_node_track_caller(size_t size, gfp_t flags,
int node, unsigned long caller)
{
return __do_kmalloc_node(size, flags, node, caller);
}
EXPORT_SYMBOL(__kmalloc_node_track_caller);
void *kmalloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size)
{
void *ret = slab_alloc_node(s, NULL, gfpflags, NUMA_NO_NODE,
_RET_IP_, size);
trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags, NUMA_NO_NODE);
ret = kasan_kmalloc(s, ret, size, gfpflags);
return ret;
}
EXPORT_SYMBOL(kmalloc_trace);
void *kmalloc_node_trace(struct kmem_cache *s, gfp_t gfpflags,
int node, size_t size)
{
void *ret = slab_alloc_node(s, NULL, gfpflags, node, _RET_IP_, size);
trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags, node);
ret = kasan_kmalloc(s, ret, size, gfpflags);
return ret;
}
EXPORT_SYMBOL(kmalloc_node_trace);
static noinline void free_to_partial_list(
struct kmem_cache *s, struct slab *slab,
void *head, void *tail, int bulk_cnt,
unsigned long addr)
{
struct kmem_cache_node *n = get_node(s, slab_nid(slab));
struct slab *slab_free = NULL;
int cnt = bulk_cnt;
unsigned long flags;
depot_stack_handle_t handle = 0;
if (s->flags & SLAB_STORE_USER)
handle = set_track_prepare();
spin_lock_irqsave(&n->list_lock, flags);
if (free_debug_processing(s, slab, head, tail, &cnt, addr, handle)) {
void *prior = slab->freelist;
/* Perform the actual freeing while we still hold the locks */
slab->inuse -= cnt;
set_freepointer(s, tail, prior);
slab->freelist = head;
/*
* If the slab is empty, and node's partial list is full,
* it should be discarded anyway no matter it's on full or
* partial list.
*/
if (slab->inuse == 0 && n->nr_partial >= s->min_partial)
slab_free = slab;
if (!prior) {
/* was on full list */
remove_full(s, n, slab);
if (!slab_free) {
add_partial(n, slab, DEACTIVATE_TO_TAIL);
stat(s, FREE_ADD_PARTIAL);
}
} else if (slab_free) {
remove_partial(n, slab);
stat(s, FREE_REMOVE_PARTIAL);
}
}
if (slab_free) {
/*
* Update the counters while still holding n->list_lock to
* prevent spurious validation warnings
*/
dec_slabs_node(s, slab_nid(slab_free), slab_free->objects);
}
spin_unlock_irqrestore(&n->list_lock, flags);
if (slab_free) {
stat(s, FREE_SLAB);
free_slab(s, slab_free);
}
}
/*
* 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 slab
* handling required then we can return immediately.
*/
static void __slab_free(struct kmem_cache *s, struct slab *slab,
void *head, void *tail, int cnt,
unsigned long addr)
{
void *prior;
int was_frozen;
struct slab new;
unsigned long counters;
struct kmem_cache_node *n = NULL;
unsigned long flags;
bool on_node_partial;
stat(s, FREE_SLOWPATH);
if (IS_ENABLED(CONFIG_SLUB_TINY) || kmem_cache_debug(s)) {
free_to_partial_list(s, slab, head, tail, cnt, addr);
return;
}
do {
if (unlikely(n)) {
spin_unlock_irqrestore(&n->list_lock, flags);
n = NULL;
}
prior = slab->freelist;
counters = slab->counters;
set_freepointer(s, tail, prior);
new.counters = counters;
was_frozen = new.frozen;
new.inuse -= cnt;
if ((!new.inuse || !prior) && !was_frozen) {
/* Needs to be taken off a list */
if (!kmem_cache_has_cpu_partial(s) || prior) {
n = get_node(s, slab_nid(slab));
/*
* 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);
on_node_partial = slab_test_node_partial(slab);
}
}
} while (!slab_update_freelist(s, slab,
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 (kmem_cache_has_cpu_partial(s) && !prior) {
/*
* If we started with a full slab then put it onto the
* per cpu partial list.
*/
put_cpu_partial(s, slab, 1);
stat(s, CPU_PARTIAL_FREE);
}
return;
}
/*
* This slab was partially empty but not on the per-node partial list,
* in which case we shouldn't manipulate its list, just return.
*/
if (prior && !on_node_partial) {
spin_unlock_irqrestore(&n->list_lock, flags);
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)) {
add_partial(n, slab, 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, slab);
stat(s, FREE_REMOVE_PARTIAL);
}
spin_unlock_irqrestore(&n->list_lock, flags);
stat(s, FREE_SLAB);
discard_slab(s, slab);
}
#ifndef CONFIG_SLUB_TINY
/*
* 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 slab) 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 slab *slab, void *head, void *tail,
int cnt, unsigned long addr)
{
struct kmem_cache_cpu *c;
unsigned long tid;
void **freelist;
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.
*/
c = raw_cpu_ptr(s->cpu_slab);
tid = READ_ONCE(c->tid);
/* Same with comment on barrier() in slab_alloc_node() */
barrier();
if (unlikely(slab != c->slab)) {
__slab_free(s, slab, head, tail, cnt, addr);
return;
}
if (USE_LOCKLESS_FAST_PATH()) {
freelist = READ_ONCE(c->freelist);
set_freepointer(s, tail, freelist);
if (unlikely(!__update_cpu_freelist_fast(s, freelist, head, tid))) {
note_cmpxchg_failure("slab_free", s, tid);
goto redo;
}
} else {
/* Update the free list under the local lock */
local_lock(&s->cpu_slab->lock);
c = this_cpu_ptr(s->cpu_slab);
if (unlikely(slab != c->slab)) {
local_unlock(&s->cpu_slab->lock);
goto redo;
}
tid = c->tid;
freelist = c->freelist;
set_freepointer(s, tail, freelist);
c->freelist = head;
c->tid = next_tid(tid);
local_unlock(&s->cpu_slab->lock);
}
stat_add(s, FREE_FASTPATH, cnt);
}
#else /* CONFIG_SLUB_TINY */
static void do_slab_free(struct kmem_cache *s,
struct slab *slab, void *head, void *tail,
int cnt, unsigned long addr)
{
__slab_free(s, slab, head, tail, cnt, addr);
}
#endif /* CONFIG_SLUB_TINY */
static __fastpath_inline
void slab_free(struct kmem_cache *s, struct slab *slab, void *object,
unsigned long addr)
{
memcg_slab_free_hook(s, slab, &object, 1);
if (likely(slab_free_hook(s, object, slab_want_init_on_free(s))))
do_slab_free(s, slab, object, object, 1, addr);
}
static __fastpath_inline
void slab_free_bulk(struct kmem_cache *s, struct slab *slab, void *head,
void *tail, void **p, int cnt, unsigned long addr)
{
memcg_slab_free_hook(s, slab, p, cnt);
/*
* With KASAN enabled slab_free_freelist_hook modifies the freelist
* to remove objects, whose reuse must be delayed.
*/
if (likely(slab_free_freelist_hook(s, &head, &tail, &cnt)))
do_slab_free(s, slab, 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_slab(x), x, x, 1, addr);
}
#endif
static inline struct kmem_cache *virt_to_cache(const void *obj)
{
struct slab *slab;
slab = virt_to_slab(obj);
if (WARN_ONCE(!slab, "%s: Object is not a Slab page!\n", __func__))
return NULL;
return slab->slab_cache;
}
static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)
{
struct kmem_cache *cachep;
if (!IS_ENABLED(CONFIG_SLAB_FREELIST_HARDENED) &&
!kmem_cache_debug_flags(s, SLAB_CONSISTENCY_CHECKS))
return s;
cachep = virt_to_cache(x);
if (WARN(cachep && cachep != s,
"%s: Wrong slab cache. %s but object is from %s\n",
__func__, s->name, cachep->name))
print_tracking(cachep, x);
return cachep;
}
/**
* kmem_cache_free - Deallocate an object
* @s: The cache the allocation was from.
* @x: The previously allocated object.
*
* Free an object which was previously allocated from this
* cache.
*/
void kmem_cache_free(struct kmem_cache *s, void *x)
{
s = cache_from_obj(s, x);
if (!s)
return;
trace_kmem_cache_free(_RET_IP_, x, s);
slab_free(s, virt_to_slab(x), x, _RET_IP_);
}
EXPORT_SYMBOL(kmem_cache_free);
static void free_large_kmalloc(struct folio *folio, void *object)
{
unsigned int order = folio_order(folio);
if (WARN_ON_ONCE(order == 0))
pr_warn_once("object pointer: 0x%p\n", object);
kmemleak_free(object);
kasan_kfree_large(object);
kmsan_kfree_large(object);
lruvec_stat_mod_folio(folio, NR_SLAB_UNRECLAIMABLE_B,
-(PAGE_SIZE << order));
folio_put(folio);
}
/**
* kfree - free previously allocated memory
* @object: pointer returned by kmalloc() or kmem_cache_alloc()
*
* If @object is NULL, no operation is performed.
*/
void kfree(const void *object)
{
struct folio *folio;
struct slab *slab;
struct kmem_cache *s;
void *x = (void *)object;
trace_kfree(_RET_IP_, object);
if (unlikely(ZERO_OR_NULL_PTR(object)))
return;
folio = virt_to_folio(object);
if (unlikely(!folio_test_slab(folio))) {
free_large_kmalloc(folio, (void *)object);
return;
}
slab = folio_slab(folio);
s = slab->slab_cache;
slab_free(s, slab, x, _RET_IP_);
}
EXPORT_SYMBOL(kfree);
struct detached_freelist {
struct slab *slab;
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
* slab. It builds a detached freelist directly within the given
* slab/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)
{
int lookahead = 3;
void *object;
struct folio *folio;
size_t same;
object = p[--size];
folio = virt_to_folio(object);
if (!s) {
/* Handle kalloc'ed objects */
if (unlikely(!folio_test_slab(folio))) {
free_large_kmalloc(folio, object);
df->slab = NULL;
return size;
}
/* Derive kmem_cache from object */
df->slab = folio_slab(folio);
df->s = df->slab->slab_cache;
} else {
df->slab = folio_slab(folio);
df->s = cache_from_obj(s, object); /* Support for memcg */
}
/* Start new detached freelist */
df->tail = object;
df->freelist = object;
df->cnt = 1;
if (is_kfence_address(object))
return size;
set_freepointer(df->s, object, NULL);
same = size;
while (size) {
object = p[--size];
/* df->slab is always set at this point */
if (df->slab == virt_to_slab(object)) {
/* Opportunity build freelist */
set_freepointer(df->s, object, df->freelist);
df->freelist = object;
df->cnt++;
same--;
if (size != same)
swap(p[size], p[same]);
continue;
}
/* Limit look ahead search */
if (!--lookahead)
break;
}
return same;
}
/*
* Internal bulk free of objects that were not initialised by the post alloc
* hooks and thus should not be processed by the free hooks
*/
static void __kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p)
{
if (!size)
return;
do {
struct detached_freelist df;
size = build_detached_freelist(s, size, p, &df);
if (!df.slab)
continue;
do_slab_free(df.s, df.slab, df.freelist, df.tail, df.cnt,
_RET_IP_);
} while (likely(size));
}
/* 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 (!size)
return;
do {
struct detached_freelist df;
size = build_detached_freelist(s, size, p, &df);
if (!df.slab)
continue;
slab_free_bulk(df.s, df.slab, df.freelist, df.tail, &p[size],
df.cnt, _RET_IP_);
} while (likely(size));
}
EXPORT_SYMBOL(kmem_cache_free_bulk);
#ifndef CONFIG_SLUB_TINY
static inline
int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
void **p)
{
struct kmem_cache_cpu *c;
unsigned long irqflags;
int i;
/*
* Drain objects in the per cpu slab, while disabling local
* IRQs, which protects against PREEMPT and interrupts
* handlers invoking normal fastpath.
*/
c = slub_get_cpu_ptr(s->cpu_slab);
local_lock_irqsave(&s->cpu_slab->lock, irqflags);
for (i = 0; i < size; i++) {
void *object = kfence_alloc(s, s->object_size, flags);
if (unlikely(object)) {
p[i] = object;
continue;
}
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);
local_unlock_irqrestore(&s->cpu_slab->lock, irqflags);
/*
* 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, s->object_size);
if (unlikely(!p[i]))
goto error;
c = this_cpu_ptr(s->cpu_slab);
maybe_wipe_obj_freeptr(s, p[i]);
local_lock_irqsave(&s->cpu_slab->lock, irqflags);
continue; /* goto for-loop */
}
c->freelist = get_freepointer(s, object);
p[i] = object;
maybe_wipe_obj_freeptr(s, p[i]);
stat(s, ALLOC_FASTPATH);
}
c->tid = next_tid(c->tid);
local_unlock_irqrestore(&s->cpu_slab->lock, irqflags);
slub_put_cpu_ptr(s->cpu_slab);
return i;
error:
slub_put_cpu_ptr(s->cpu_slab);
__kmem_cache_free_bulk(s, i, p);
return 0;
}
#else /* CONFIG_SLUB_TINY */
static int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags,
size_t size, void **p)
{
int i;
for (i = 0; i < size; i++) {
void *object = kfence_alloc(s, s->object_size, flags);
if (unlikely(object)) {
p[i] = object;
continue;
}
p[i] = __slab_alloc_node(s, flags, NUMA_NO_NODE,
_RET_IP_, s->object_size);
if (unlikely(!p[i]))
goto error;
maybe_wipe_obj_freeptr(s, p[i]);
}
return i;
error:
__kmem_cache_free_bulk(s, i, p);
return 0;
}
#endif /* CONFIG_SLUB_TINY */
/* 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)
{
int i;
struct obj_cgroup *objcg = NULL;
if (!size)
return 0;
/* memcg and kmem_cache debug support */
s = slab_pre_alloc_hook(s, NULL, &objcg, size, flags);
if (unlikely(!s))
return 0;
i = __kmem_cache_alloc_bulk(s, flags, size, p);
/*
* memcg and kmem_cache debug support and memory initialization.
* Done outside of the IRQ disabled fastpath loop.
*/
if (likely(i != 0)) {
slab_post_alloc_hook(s, objcg, flags, size, p,
slab_want_init_on_alloc(flags, s), s->object_size);
} else {
memcg_slab_alloc_error_hook(s, size, objcg);
}
return i;
}
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.
*/
/*
* Minimum / 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 =
IS_ENABLED(CONFIG_SLUB_TINY) ? 1 : 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.
*
* slab_max_order specifies the order where we begin to stop considering the
* number of objects in a slab as critical. If we reach slab_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 minimum order then we start with that one instead of
* the smallest order which will fit the object.
*/
static inline unsigned int calc_slab_order(unsigned int size,
unsigned int min_order, unsigned int max_order,
unsigned int fract_leftover)
{
unsigned int order;
for (order = min_order; 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;
unsigned int min_order;
min_objects = slub_min_objects;
if (!min_objects) {
/*
* Some architectures will only update present cpus when
* onlining them, so don't trust the number if it's just 1. But
* we also don't want to use nr_cpu_ids always, as on some other
* architectures, there can be many possible cpus, but never
* onlined. Here we compromise between trying to avoid too high
* order on systems that appear larger than they are, and too
* low order on systems that appear smaller than they are.
*/
unsigned int nr_cpus = num_present_cpus();
if (nr_cpus <= 1)
nr_cpus = nr_cpu_ids;
min_objects = 4 * (fls(nr_cpus) + 1);
}
/* min_objects can't be 0 because get_order(0) is undefined */
max_objects = max(order_objects(slub_max_order, size), 1U);
min_objects = min(min_objects, max_objects);
min_order = max_t(unsigned int, slub_min_order,
get_order(min_objects * size));
if (order_objects(min_order, size) > MAX_OBJS_PER_PAGE)
return get_order(size * MAX_OBJS_PER_PAGE) - 1;
/*
* Attempt to find best configuration for a slab. This works by first
* attempting to generate a layout with the best possible configuration
* and backing off gradually.
*
* We start with accepting at most 1/16 waste and try to find the
* smallest order from min_objects-derived/slab_min_order up to
* slab_max_order that will satisfy the constraint. Note that increasing
* the order can only result in same or less fractional waste, not more.
*
* If that fails, we increase the acceptable fraction of waste and try
* again. The last iteration with fraction of 1/2 would effectively
* accept any waste and give us the order determined by min_objects, as
* long as at least single object fits within slab_max_order.
*/
for (unsigned int fraction = 16; fraction > 1; fraction /= 2) {
order = calc_slab_order(size, min_order, slub_max_order,
fraction);
if (order <= slub_max_order)
return order;
}
/*
* Doh this slab cannot be placed using slab_max_order.
*/
order = get_order(size);
if (order <= MAX_PAGE_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
}
#ifndef CONFIG_SLUB_TINY
static inline int alloc_kmem_cache_cpus(struct kmem_cache *s)
{
BUILD_BUG_ON(PERCPU_DYNAMIC_EARLY_SIZE <
NR_KMALLOC_TYPES * 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;
}
#else
static inline int alloc_kmem_cache_cpus(struct kmem_cache *s)
{
return 1;
}
#endif /* CONFIG_SLUB_TINY */
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 slab *slab;
struct kmem_cache_node *n;
BUG_ON(kmem_cache_node->size < sizeof(struct kmem_cache_node));
slab = new_slab(kmem_cache_node, GFP_NOWAIT, node);
BUG_ON(!slab);
if (slab_nid(slab) != 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 = slab->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_slab_alloc(kmem_cache_node, n, GFP_KERNEL, false);
slab->freelist = get_freepointer(kmem_cache_node, n);
slab->inuse = 1;
kmem_cache_node->node[node] = n;
init_kmem_cache_node(n);
inc_slabs_node(kmem_cache_node, node, slab->objects);
/*
* No locks need to be taken here as it has just been
* initialized and there is no concurrent access.
*/
__add_partial(n, slab, 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);
#ifndef CONFIG_SLUB_TINY
free_percpu(s->cpu_slab);
#endif
free_kmem_cache_nodes(s);
}
static int init_kmem_cache_nodes(struct kmem_cache *s)
{
int node;
for_each_node_mask(node, slab_nodes) {
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_cpu_partial(struct kmem_cache *s)
{
#ifdef CONFIG_SLUB_CPU_PARTIAL
unsigned int nr_objects;
/*
* 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.
*
* For backwards compatibility reasons, this is determined as number
* of objects, even though we now limit maximum number of pages, see
* slub_set_cpu_partial()
*/
if (!kmem_cache_has_cpu_partial(s))
nr_objects = 0;
else if (s->size >= PAGE_SIZE)
nr_objects = 6;
else if (s->size >= 1024)
nr_objects = 24;
else if (s->size >= 256)
nr_objects = 52;
else
nr_objects = 120;
slub_set_cpu_partial(s, nr_objects);
#endif
}
/*
* calculate_sizes() determines the order and the distribution of data within
* a slab object.
*/
static int calculate_sizes(struct kmem_cache *s)
{
slab_flags_t flags = s->flags;
unsigned int size = s->object_size;
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 *));
#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 and redzoning.
*/
s->inuse = size;
if (slub_debug_orig_size(s) ||
(flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)) ||
((flags & SLAB_RED_ZONE) && s->object_size < sizeof(void *)) ||
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, are poisoning the objects, or are
* redzoning an object smaller than sizeof(void *).
*
* 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 {
/*
* 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_DOWN(s->object_size / 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);
/* Save the original kmalloc request size */
if (flags & SLAB_KMALLOC)
size += sizeof(unsigned int);
}
#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);
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);
return !!oo_objects(s->oo);
}
static int kmem_cache_open(struct kmem_cache *s, slab_flags_t flags)
{
s->flags = kmem_cache_flags(flags, s->name);
#ifdef CONFIG_SLAB_FREELIST_HARDENED
s->random = get_random_long();
#endif
if (!calculate_sizes(s))
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))
goto error;
}
}
#ifdef system_has_freelist_aba
if (system_has_freelist_aba() && !(s->flags & SLAB_NO_CMPXCHG)) {
/* Enable fast mode */
s->flags |= __CMPXCHG_DOUBLE;
}
#endif
/*
* The larger the object size is, the more slabs we want on the partial
* list to avoid pounding the page allocator excessively.
*/
s->min_partial = min_t(unsigned long, MAX_PARTIAL, ilog2(s->size) / 2);
s->min_partial = max_t(unsigned long, MIN_PARTIAL, s->min_partial);
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;
error:
__kmem_cache_release(s);
return -EINVAL;
}
static void list_slab_objects(struct kmem_cache *s, struct slab *slab,
const char *text)
{
#ifdef CONFIG_SLUB_DEBUG
void *addr = slab_address(slab);
void *p;
slab_err(s, slab, text, s->name);
spin_lock(&object_map_lock);
__fill_map(object_map, s, slab);
for_each_object(p, s, addr, slab->objects) {
if (!test_bit(__obj_to_index(s, addr, p), object_map)) {
pr_err("Object 0x%p @offset=%tu\n", p, p - addr);
print_tracking(s, p);
}
}
spin_unlock(&object_map_lock);
#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 slab *slab, *h;
BUG_ON(irqs_disabled());
spin_lock_irq(&n->list_lock);
list_for_each_entry_safe(slab, h, &n->partial, slab_list) {
if (!slab->inuse) {
remove_partial(n, slab);
list_add(&slab->slab_list, &discard);
} else {
list_slab_objects(s, slab,
"Objects remaining in %s on __kmem_cache_shutdown()");
}
}
spin_unlock_irq(&n->list_lock);
list_for_each_entry_safe(slab, h, &discard, slab_list)
discard_slab(s, slab);
}
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 || node_nr_slabs(n))
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_cpus_locked(s);
/* Attempt to free all objects */
for_each_kmem_cache_node(s, node, n) {
free_partial(s, n);
if (n->nr_partial || node_nr_slabs(n))
return 1;
}
return 0;
}
#ifdef CONFIG_PRINTK
void __kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab)
{
void *base;
int __maybe_unused i;
unsigned int objnr;
void *objp;
void *objp0;
struct kmem_cache *s = slab->slab_cache;
struct track __maybe_unused *trackp;
kpp->kp_ptr = object;
kpp->kp_slab = slab;
kpp->kp_slab_cache = s;
base = slab_address(slab);
objp0 = kasan_reset_tag(object);
#ifdef CONFIG_SLUB_DEBUG
objp = restore_red_left(s, objp0);
#else
objp = objp0;
#endif
objnr = obj_to_index(s, slab, objp);
kpp->kp_data_offset = (unsigned long)((char *)objp0 - (char *)objp);
objp = base + s->size * objnr;
kpp->kp_objp = objp;
if (WARN_ON_ONCE(objp < base || objp >= base + slab->objects * s->size
|| (objp - base) % s->size) ||
!(s->flags & SLAB_STORE_USER))
return;
#ifdef CONFIG_SLUB_DEBUG
objp = fixup_red_left(s, objp);
trackp = get_track(s, objp, TRACK_ALLOC);
kpp->kp_ret = (void *)trackp->addr;
#ifdef CONFIG_STACKDEPOT
{
depot_stack_handle_t handle;
unsigned long *entries;
unsigned int nr_entries;
handle = READ_ONCE(trackp->handle);
if (handle) {
nr_entries = stack_depot_fetch(handle, &entries);
for (i = 0; i < KS_ADDRS_COUNT && i < nr_entries; i++)
kpp->kp_stack[i] = (void *)entries[i];
}
trackp = get_track(s, objp, TRACK_FREE);
handle = READ_ONCE(trackp->handle);
if (handle) {
nr_entries = stack_depot_fetch(handle, &entries);
for (i = 0; i < KS_ADDRS_COUNT && i < nr_entries; i++)
kpp->kp_free_stack[i] = (void *)entries[i];
}
}
#endif
#endif
}
#endif
/********************************************************************
* Kmalloc subsystem
*******************************************************************/
static int __init setup_slub_min_order(char *str)
{
get_option(&str, (int *)&slub_min_order);
if (slub_min_order > slub_max_order)
slub_max_order = slub_min_order;
return 1;
}
__setup("slab_min_order=", setup_slub_min_order);
__setup_param("slub_min_order=", slub_min_order, setup_slub_min_order, 0);
static int __init setup_slub_max_order(char *str)
{
get_option(&str, (int *)&slub_max_order);
slub_max_order = min_t(unsigned int, slub_max_order, MAX_PAGE_ORDER);
if (slub_min_order > slub_max_order)
slub_min_order = slub_max_order;
return 1;
}
__setup("slab_max_order=", setup_slub_max_order);
__setup_param("slub_max_order=", slub_max_order, setup_slub_max_order, 0);
static int __init setup_slub_min_objects(char *str)
{
get_option(&str, (int *)&slub_min_objects);
return 1;
}
__setup("slab_min_objects=", setup_slub_min_objects);
__setup_param("slub_min_objects=", slub_min_objects, setup_slub_min_objects, 0);
#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,
const struct slab *slab, bool to_user)
{
struct kmem_cache *s;
unsigned int offset;
bool is_kfence = is_kfence_address(ptr);
ptr = kasan_reset_tag(ptr);
/* Find object and usable object size. */
s = slab->slab_cache;
/* Reject impossible pointers. */
if (ptr < slab_address(slab))
usercopy_abort("SLUB object not in SLUB page?!", NULL,
to_user, 0, n);
/* Find offset within object. */
if (is_kfence)
offset = ptr - kfence_object_start(ptr);
else
offset = (ptr - slab_address(slab)) % s->size;
/* Adjust for redzone and reject if within the redzone. */
if (!is_kfence && 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;
usercopy_abort("SLUB object", s->name, to_user, offset, n);
}
#endif /* CONFIG_HARDENED_USERCOPY */
#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.
*/
static int __kmem_cache_do_shrink(struct kmem_cache *s)
{
int node;
int i;
struct kmem_cache_node *n;
struct slab *slab;
struct slab *t;
struct list_head discard;
struct list_head promote[SHRINK_PROMOTE_MAX];
unsigned long flags;
int ret = 0;
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. slab->inuse here is the upper limit.
*/
list_for_each_entry_safe(slab, t, &n->partial, slab_list) {
int free = slab->objects - slab->inuse;
/* Do not reread slab->inuse */
barrier();
/* We do not keep full slabs on the list */
BUG_ON(free <= 0);
if (free == slab->objects) {
list_move(&slab->slab_list, &discard);
slab_clear_node_partial(slab);
n->nr_partial--;
dec_slabs_node(s, node, slab->objects);
} else if (free <= SHRINK_PROMOTE_MAX)
list_move(&slab->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(slab, t, &discard, slab_list)
free_slab(s, slab);
if (node_nr_slabs(n))
ret = 1;
}
return ret;
}
int __kmem_cache_shrink(struct kmem_cache *s)
{
flush_all(s);
return __kmem_cache_do_shrink(s);
}
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) {
flush_all_cpus_locked(s);
__kmem_cache_do_shrink(s);
}
mutex_unlock(&slab_mutex);
return 0;
}
static void slab_mem_offline_callback(void *arg)
{
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);
node_clear(offline_node, slab_nodes);
/*
* We no longer free kmem_cache_node structures here, as it would be
* racy with all get_node() users, and infeasible to protect them with
* slab_mutex.
*/
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) {
/*
* The structure may already exist if the node was previously
* onlined and offlined.
*/
if (get_node(s, nid))
continue;
/*
* 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;
}
/*
* Any cache created after this point will also have kmem_cache_node
* initialized for the new node.
*/
node_set(nid, slab_nodes);
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;
}
/********************************************************************
* 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 slab *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;
int node;
if (debug_guardpage_minorder())
slub_max_order = 0;
/* Print slub debugging pointers without hashing */
if (__slub_debug_enabled())
no_hash_pointers_enable(NULL);
kmem_cache_node = &boot_kmem_cache_node;
kmem_cache = &boot_kmem_cache;
/*
* Initialize the nodemask for which we will allocate per node
* structures. Here we don't need taking slab_mutex yet.
*/
for_each_node_state(node, N_NORMAL_MEMORY)
node_set(node, slab_nodes);
create_boot_cache(kmem_cache_node, "kmem_cache_node",
sizeof(struct kmem_cache_node), SLAB_HWCACHE_ALIGN, 0, 0);
hotplug_memory_notifier(slab_memory_callback, SLAB_CALLBACK_PRI);
/* 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();
/* 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)
{
#ifndef CONFIG_SLUB_TINY
flushwq = alloc_workqueue("slub_flushwq", WQ_MEM_RECLAIM, 0);
WARN_ON(!flushwq);
#endif
}
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) {
if (sysfs_slab_alias(s, name))
return NULL;
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 *)));
}
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;
}
if (s->flags & SLAB_STORE_USER)
debugfs_slab_add(s);
return 0;
}
#ifdef SLAB_SUPPORTS_SYSFS
static int count_inuse(struct slab *slab)
{
return slab->inuse;
}
static int count_total(struct slab *slab)
{
return slab->objects;
}
#endif
#ifdef CONFIG_SLUB_DEBUG
static void validate_slab(struct kmem_cache *s, struct slab *slab,
unsigned long *obj_map)
{
void *p;
void *addr = slab_address(slab);
if (!check_slab(s, slab) || !on_freelist(s, slab, NULL))
return;
/* Now we know that a valid freelist exists */
__fill_map(obj_map, s, slab);
for_each_object(p, s, addr, slab->objects) {
u8 val = test_bit(__obj_to_index(s, addr, p), obj_map) ?
SLUB_RED_INACTIVE : SLUB_RED_ACTIVE;
if (!check_object(s, slab, p, val))
break;
}
}
static int validate_slab_node(struct kmem_cache *s,
struct kmem_cache_node *n, unsigned long *obj_map)
{
unsigned long count = 0;
struct slab *slab;
unsigned long flags;
spin_lock_irqsave(&n->list_lock, flags);
list_for_each_entry(slab, &n->partial, slab_list) {
validate_slab(s, slab, obj_map);
count++;
}
if (count != n->nr_partial) {
pr_err("SLUB %s: %ld partial slabs counted but counter=%ld\n",
s->name, count, n->nr_partial);
slab_add_kunit_errors();
}
if (!(s->flags & SLAB_STORE_USER))
goto out;
list_for_each_entry(slab, &n->full, slab_list) {
validate_slab(s, slab, obj_map);
count++;
}
if (count != node_nr_slabs(n)) {
pr_err("SLUB: %s %ld slabs counted but counter=%ld\n",
s->name, count, node_nr_slabs(n));
slab_add_kunit_errors();
}
out:
spin_unlock_irqrestore(&n->list_lock, flags);
return count;
}
long validate_slab_cache(struct kmem_cache *s)
{
int node;
unsigned long count = 0;
struct kmem_cache_node *n;
unsigned long *obj_map;
obj_map = bitmap_alloc(oo_objects(s->oo), GFP_KERNEL);
if (!obj_map)
return -ENOMEM;
flush_all(s);
for_each_kmem_cache_node(s, node, n)
count += validate_slab_node(s, n, obj_map);
bitmap_free(obj_map);
return count;
}
EXPORT_SYMBOL(validate_slab_cache);
#ifdef CONFIG_DEBUG_FS
/*
* Generate lists of code addresses where slabcache objects are allocated
* and freed.
*/
struct location {
depot_stack_handle_t handle;
unsigned long count;
unsigned long addr;
unsigned long waste;
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;
loff_t idx;
};
static struct dentry *slab_debugfs_root;
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,
unsigned int orig_size)
{
long start, end, pos;
struct location *l;
unsigned long caddr, chandle, cwaste;
unsigned long age = jiffies - track->when;
depot_stack_handle_t handle = 0;
unsigned int waste = s->object_size - orig_size;
#ifdef CONFIG_STACKDEPOT
handle = READ_ONCE(track->handle);
#endif
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;
l = &t->loc[pos];
caddr = l->addr;
chandle = l->handle;
cwaste = l->waste;
if ((track->addr == caddr) && (handle == chandle) &&
(waste == cwaste)) {
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 if (track->addr == caddr && handle < chandle)
end = pos;
else if (track->addr == caddr && handle == chandle &&
waste < cwaste)
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;
l->handle = handle;
l->waste = waste;
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 slab *slab, enum track_item alloc,
unsigned long *obj_map)
{
void *addr = slab_address(slab);
bool is_alloc = (alloc == TRACK_ALLOC);
void *p;
__fill_map(obj_map, s, slab);
for_each_object(p, s, addr, slab->objects)
if (!test_bit(__obj_to_index(s, addr, p), obj_map))
add_location(t, s, get_track(s, p, alloc),
is_alloc ? get_orig_size(s, p) :
s->object_size);
}
#endif /* CONFIG_DEBUG_FS */
#endif /* CONFIG_SLUB_DEBUG */
#ifdef SLAB_SUPPORTS_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)
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;
int len = 0;
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 slab *slab;
slab = READ_ONCE(c->slab);
if (!slab)
continue;
node = slab_nid(slab);
if (flags & SO_TOTAL)
x = slab->objects;
else if (flags & SO_OBJECTS)
x = slab->inuse;
else
x = 1;
total += x;
nodes[node] += x;
#ifdef CONFIG_SLUB_CPU_PARTIAL
slab = slub_percpu_partial_read_once(c);
if (slab) {
node = slab_nid(slab);
if (flags & SO_TOTAL)
WARN_ON_ONCE(1);
else if (flags & SO_OBJECTS)
WARN_ON_ONCE(1);
else
x = slab->slabs;
total += x;
nodes[node] += x;
}
#endif
}
}
/*
* 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 = node_nr_objs(n);
else if (flags & SO_OBJECTS)
x = node_nr_objs(n) - count_partial(n, count_free);
else
x = node_nr_slabs(n);
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;
}
}
len += sysfs_emit_at(buf, len, "%lu", total);
#ifdef CONFIG_NUMA
for (node = 0; node < nr_node_ids; node++) {
if (nodes[node])
len += sysfs_emit_at(buf, len, " N%d=%lu",
node, nodes[node]);
}
#endif
len += sysfs_emit_at(buf, len, "\n");
kfree(nodes);
return len;
}
#define to_slab_attr(n) container_of(n, struct slab_attribute, attr)
#define to_slab(n) container_of(n, struct kmem_cache, kobj)
struct slab_attribute {
struct attribute attr;
ssize_t (*show)(struct kmem_cache *s, char *buf);
ssize_t (*store)(struct kmem_cache *s, const char *x, size_t count);
};
#define SLAB_ATTR_RO(_name) \
static struct slab_attribute _name##_attr = __ATTR_RO_MODE(_name, 0400)
#define SLAB_ATTR(_name) \
static struct slab_attribute _name##_attr = __ATTR_RW_MODE(_name, 0600)
static ssize_t slab_size_show(struct kmem_cache *s, char *buf)
{
return sysfs_emit(buf, "%u\n", s->size);
}
SLAB_ATTR_RO(slab_size);
static ssize_t align_show(struct kmem_cache *s, char *buf)
{
return sysfs_emit(buf, "%u\n", s->align);
}
SLAB_ATTR_RO(align);
static ssize_t object_size_show(struct kmem_cache *s, char *buf)
{
return sysfs_emit(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 sysfs_emit(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 sysfs_emit(buf, "%u\n", oo_order(s->oo));
}
SLAB_ATTR_RO(order);
static ssize_t min_partial_show(struct kmem_cache *s, char *buf)
{
return sysfs_emit(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;
s->min_partial = min;
return length;
}
SLAB_ATTR(min_partial);
static ssize_t cpu_partial_show(struct kmem_cache *s, char *buf)
{
unsigned int nr_partial = 0;
#ifdef CONFIG_SLUB_CPU_PARTIAL
nr_partial = s->cpu_partial;
#endif
return sysfs_emit(buf, "%u\n", nr_partial);
}
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 sysfs_emit(buf, "%pS\n", s->ctor);
}
SLAB_ATTR_RO(ctor);
static ssize_t aliases_show(struct kmem_cache *s, char *buf)
{
return sysfs_emit(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_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 slabs = 0;
int cpu __maybe_unused;
int len = 0;
#ifdef CONFIG_SLUB_CPU_PARTIAL
for_each_online_cpu(cpu) {
struct slab *slab;
slab = slub_percpu_partial(per_cpu_ptr(s->cpu_slab, cpu));
if (slab)
slabs += slab->slabs;
}
#endif
/* Approximate half-full slabs, see slub_set_cpu_partial() */
objects = (slabs * oo_objects(s->oo)) / 2;
len += sysfs_emit_at(buf, len, "%d(%d)", objects, slabs);
#ifdef CONFIG_SLUB_CPU_PARTIAL
for_each_online_cpu(cpu) {
struct slab *slab;
slab = slub_percpu_partial(per_cpu_ptr(s->cpu_slab, cpu));
if (slab) {
slabs = READ_ONCE(slab->slabs);
objects = (slabs * oo_objects(s->oo)) / 2;
len += sysfs_emit_at(buf, len, " C%d=%d(%d)",
cpu, objects, slabs);
}
}
#endif
len += sysfs_emit_at(buf, len, "\n");
return len;
}
SLAB_ATTR_RO(slabs_cpu_partial);
static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
{
return sysfs_emit(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 sysfs_emit(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 sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_CACHE_DMA));
}
SLAB_ATTR_RO(cache_dma);
#endif
#ifdef CONFIG_HARDENED_USERCOPY
static ssize_t usersize_show(struct kmem_cache *s, char *buf)
{
return sysfs_emit(buf, "%u\n", s->usersize);
}
SLAB_ATTR_RO(usersize);
#endif
static ssize_t destroy_by_rcu_show(struct kmem_cache *s, char *buf)
{
return sysfs_emit(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 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 sanity_checks_show(struct kmem_cache *s, char *buf)
{
return sysfs_emit(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 sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_TRACE));
}
SLAB_ATTR_RO(trace);
static ssize_t red_zone_show(struct kmem_cache *s, char *buf)
{
return sysfs_emit(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 sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_POISON));
}
SLAB_ATTR_RO(poison);
static ssize_t store_user_show(struct kmem_cache *s, char *buf)
{
return sysfs_emit(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' && kmem_cache_debug(s)) {
ret = validate_slab_cache(s);
if (ret >= 0)
ret = length;
}
return ret;
}
SLAB_ATTR(validate);
#endif /* CONFIG_SLUB_DEBUG */
#ifdef CONFIG_FAILSLAB
static ssize_t failslab_show(struct kmem_cache *s, char *buf)
{
return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_FAILSLAB));
}
static ssize_t failslab_store(struct kmem_cache *s, const char *buf,
size_t length)
{
if (s->refcount > 1)
return -EINVAL;
if (buf[0] == '1')
WRITE_ONCE(s->flags, s->flags | SLAB_FAILSLAB);
else
WRITE_ONCE(s->flags, s->flags & ~SLAB_FAILSLAB);
return length;
}
SLAB_ATTR(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 sysfs_emit(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 = 0;
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 += sysfs_emit_at(buf, len, "%lu", sum);
#ifdef CONFIG_SMP
for_each_online_cpu(cpu) {
if (data[cpu])
len += sysfs_emit_at(buf, len, " C%d=%u",
cpu, data[cpu]);
}
#endif
kfree(data);
len += sysfs_emit_at(buf, len, "\n");
return len;
}
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 */
#ifdef CONFIG_KFENCE
static ssize_t skip_kfence_show(struct kmem_cache *s, char *buf)
{
return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_SKIP_KFENCE));
}
static ssize_t skip_kfence_store(struct kmem_cache *s,
const char *buf, size_t length)
{
int ret = length;
if (buf[0] == '0')
s->flags &= ~SLAB_SKIP_KFENCE;
else if (buf[0] == '1')
s->flags |= SLAB_SKIP_KFENCE;
else
ret = -EINVAL;
return ret;
}
SLAB_ATTR(skip_kfence);
#endif
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_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,
&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,
#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
#ifdef CONFIG_HARDENED_USERCOPY
&usersize_attr.attr,
#endif
#ifdef CONFIG_KFENCE
&skip_kfence_attr.attr,
#endif
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;
attribute = to_slab_attr(attr);
s = to_slab(kobj);
if (!attribute->show)
return -EIO;
return attribute->show(s, buf);
}
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;
attribute = to_slab_attr(attr);
s = to_slab(kobj);
if (!attribute->store)
return -EIO;
return attribute->store(s, buf, len);
}
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 const 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 32
/* 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;
if (!name)
return ERR_PTR(-ENOMEM);
*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 += snprintf(p, ID_STR_LENGTH - (p - name), "%07u", s->size);
if (WARN_ON(p > name + ID_STR_LENGTH - 1)) {
kfree(name);
return ERR_PTR(-EINVAL);
}
kmsan_unpoison_memory(name, p - name);
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 (!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);
if (IS_ERR(name))
return PTR_ERR(name);
}
s->kobj.kset = kset;
err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name);
if (err)
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)
{
kobject_del(&s->kobj);
}
void sysfs_slab_release(struct kmem_cache *s)
{
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;
kmsan_unpoison_memory(al, sizeof(*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 -ENOMEM;
}
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);
return 0;
}
late_initcall(slab_sysfs_init);
#endif /* SLAB_SUPPORTS_SYSFS */
#if defined(CONFIG_SLUB_DEBUG) && defined(CONFIG_DEBUG_FS)
static int slab_debugfs_show(struct seq_file *seq, void *v)
{
struct loc_track *t = seq->private;
struct location *l;
unsigned long idx;
idx = (unsigned long) t->idx;
if (idx < t->count) {
l = &t->loc[idx];
seq_printf(seq, "%7ld ", l->count);
if (l->addr)
seq_printf(seq, "%pS", (void *)l->addr);
else
seq_puts(seq, "<not-available>");
if (l->waste)
seq_printf(seq, " waste=%lu/%lu",
l->count * l->waste, l->waste);
if (l->sum_time != l->min_time) {
seq_printf(seq, " age=%ld/%llu/%ld",
l->min_time, div_u64(l->sum_time, l->count),
l->max_time);
} else
seq_printf(seq, " age=%ld", l->min_time);
if (l->min_pid != l->max_pid)
seq_printf(seq, " pid=%ld-%ld", l->min_pid, l->max_pid);
else
seq_printf(seq, " pid=%ld",
l->min_pid);
if (num_online_cpus() > 1 && !cpumask_empty(to_cpumask(l->cpus)))
seq_printf(seq, " cpus=%*pbl",
cpumask_pr_args(to_cpumask(l->cpus)));
if (nr_online_nodes > 1 && !nodes_empty(l->nodes))
seq_printf(seq, " nodes=%*pbl",
nodemask_pr_args(&l->nodes));
#ifdef CONFIG_STACKDEPOT
{
depot_stack_handle_t handle;
unsigned long *entries;
unsigned int nr_entries, j;
handle = READ_ONCE(l->handle);
if (handle) {
nr_entries = stack_depot_fetch(handle, &entries);
seq_puts(seq, "\n");
for (j = 0; j < nr_entries; j++)
seq_printf(seq, " %pS\n", (void *)entries[j]);
}
}
#endif
seq_puts(seq, "\n");
}
if (!idx && !t->count)
seq_puts(seq, "No data\n");
return 0;
}
static void slab_debugfs_stop(struct seq_file *seq, void *v)
{
}
static void *slab_debugfs_next(struct seq_file *seq, void *v, loff_t *ppos)
{
struct loc_track *t = seq->private;
t->idx = ++(*ppos);
if (*ppos <= t->count)
return ppos;
return NULL;
}
static int cmp_loc_by_count(const void *a, const void *b, const void *data)
{
struct location *loc1 = (struct location *)a;
struct location *loc2 = (struct location *)b;
if (loc1->count > loc2->count)
return -1;
else
return 1;
}
static void *slab_debugfs_start(struct seq_file *seq, loff_t *ppos)
{
struct loc_track *t = seq->private;
t->idx = *ppos;
return ppos;
}
static const struct seq_operations slab_debugfs_sops = {
.start = slab_debugfs_start,
.next = slab_debugfs_next,
.stop = slab_debugfs_stop,
.show = slab_debugfs_show,
};
static int slab_debug_trace_open(struct inode *inode, struct file *filep)
{
struct kmem_cache_node *n;
enum track_item alloc;
int node;
struct loc_track *t = __seq_open_private(filep, &slab_debugfs_sops,
sizeof(struct loc_track));
struct kmem_cache *s = file_inode(filep)->i_private;
unsigned long *obj_map;
if (!t)
return -ENOMEM;
obj_map = bitmap_alloc(oo_objects(s->oo), GFP_KERNEL);
if (!obj_map) {
seq_release_private(inode, filep);
return -ENOMEM;
}
if (strcmp(filep->f_path.dentry->d_name.name, "alloc_traces") == 0)
alloc = TRACK_ALLOC;
else
alloc = TRACK_FREE;
if (!alloc_loc_track(t, PAGE_SIZE / sizeof(struct location), GFP_KERNEL)) {
bitmap_free(obj_map);
seq_release_private(inode, filep);
return -ENOMEM;
}
for_each_kmem_cache_node(s, node, n) {
unsigned long flags;
struct slab *slab;
if (!node_nr_slabs(n))
continue;
spin_lock_irqsave(&n->list_lock, flags);
list_for_each_entry(slab, &n->partial, slab_list)
process_slab(t, s, slab, alloc, obj_map);
list_for_each_entry(slab, &n->full, slab_list)
process_slab(t, s, slab, alloc, obj_map);
spin_unlock_irqrestore(&n->list_lock, flags);
}
/* Sort locations by count */
sort_r(t->loc, t->count, sizeof(struct location),
cmp_loc_by_count, NULL, NULL);
bitmap_free(obj_map);
return 0;
}
static int slab_debug_trace_release(struct inode *inode, struct file *file)
{
struct seq_file *seq = file->private_data;
struct loc_track *t = seq->private;
free_loc_track(t);
return seq_release_private(inode, file);
}
static const struct file_operations slab_debugfs_fops = {
.open = slab_debug_trace_open,
.read = seq_read,
.llseek = seq_lseek,
.release = slab_debug_trace_release,
};
static void debugfs_slab_add(struct kmem_cache *s)
{
struct dentry *slab_cache_dir;
if (unlikely(!slab_debugfs_root))
return;
slab_cache_dir = debugfs_create_dir(s->name, slab_debugfs_root);
debugfs_create_file("alloc_traces", 0400,
slab_cache_dir, s, &slab_debugfs_fops);
debugfs_create_file("free_traces", 0400,
slab_cache_dir, s, &slab_debugfs_fops);
}
void debugfs_slab_release(struct kmem_cache *s)
{
debugfs_lookup_and_remove(s->name, slab_debugfs_root);
}
static int __init slab_debugfs_init(void)
{
struct kmem_cache *s;
slab_debugfs_root = debugfs_create_dir("slab", NULL);
list_for_each_entry(s, &slab_caches, list)
if (s->flags & SLAB_STORE_USER)
debugfs_slab_add(s);
return 0;
}
__initcall(slab_debugfs_init);
#endif
/*
* 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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