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WSL2-Linux-Kernel/mm/slab.c

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// SPDX-License-Identifier: GPL-2.0
/*
* linux/mm/slab.c
* Written by Mark Hemment, 1996/97.
* (markhe@nextd.demon.co.uk)
*
* kmem_cache_destroy() + some cleanup - 1999 Andrea Arcangeli
*
* Major cleanup, different bufctl logic, per-cpu arrays
* (c) 2000 Manfred Spraul
*
* Cleanup, make the head arrays unconditional, preparation for NUMA
* (c) 2002 Manfred Spraul
*
* An implementation of the Slab Allocator as described in outline in;
* UNIX Internals: The New Frontiers by Uresh Vahalia
* Pub: Prentice Hall ISBN 0-13-101908-2
* or with a little more detail in;
* The Slab Allocator: An Object-Caching Kernel Memory Allocator
* Jeff Bonwick (Sun Microsystems).
* Presented at: USENIX Summer 1994 Technical Conference
*
* The memory is organized in caches, one cache for each object type.
* (e.g. inode_cache, dentry_cache, buffer_head, vm_area_struct)
* Each cache consists out of many slabs (they are small (usually one
* page long) and always contiguous), and each slab contains multiple
* initialized objects.
*
* This means, that your constructor is used only for newly allocated
* slabs and you must pass objects with the same initializations to
* kmem_cache_free.
*
* Each cache can only support one memory type (GFP_DMA, GFP_HIGHMEM,
* normal). If you need a special memory type, then must create a new
* cache for that memory type.
*
* In order to reduce fragmentation, the slabs are sorted in 3 groups:
* full slabs with 0 free objects
* partial slabs
* empty slabs with no allocated objects
*
* If partial slabs exist, then new allocations come from these slabs,
* otherwise from empty slabs or new slabs are allocated.
*
* kmem_cache_destroy() CAN CRASH if you try to allocate from the cache
* during kmem_cache_destroy(). The caller must prevent concurrent allocs.
*
* Each cache has a short per-cpu head array, most allocs
* and frees go into that array, and if that array overflows, then 1/2
* of the entries in the array are given back into the global cache.
* The head array is strictly LIFO and should improve the cache hit rates.
* On SMP, it additionally reduces the spinlock operations.
*
* The c_cpuarray may not be read with enabled local interrupts -
* it's changed with a smp_call_function().
*
* SMP synchronization:
* constructors and destructors are called without any locking.
* Several members in struct kmem_cache and struct slab never change, they
* are accessed without any locking.
* The per-cpu arrays are never accessed from the wrong cpu, no locking,
* and local interrupts are disabled so slab code is preempt-safe.
* The non-constant members are protected with a per-cache irq spinlock.
*
* Many thanks to Mark Hemment, who wrote another per-cpu slab patch
* in 2000 - many ideas in the current implementation are derived from
* his patch.
*
* Further notes from the original documentation:
*
* 11 April '97. Started multi-threading - markhe
* The global cache-chain is protected by the mutex 'slab_mutex'.
* The sem is only needed when accessing/extending the cache-chain, which
* can never happen inside an interrupt (kmem_cache_create(),
* kmem_cache_shrink() and kmem_cache_reap()).
*
* At present, each engine can be growing a cache. This should be blocked.
*
* 15 March 2005. NUMA slab allocator.
* Shai Fultheim <shai@scalex86.org>.
* Shobhit Dayal <shobhit@calsoftinc.com>
* Alok N Kataria <alokk@calsoftinc.com>
* Christoph Lameter <christoph@lameter.com>
*
* Modified the slab allocator to be node aware on NUMA systems.
* Each node has its own list of partial, free and full slabs.
* All object allocations for a node occur from node specific slab lists.
*/
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/poison.h>
#include <linux/swap.h>
#include <linux/cache.h>
#include <linux/interrupt.h>
#include <linux/init.h>
#include <linux/compiler.h>
#include <linux/cpuset.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/notifier.h>
#include <linux/kallsyms.h>
#include <linux/kfence.h>
#include <linux/cpu.h>
#include <linux/sysctl.h>
#include <linux/module.h>
#include <linux/rcupdate.h>
#include <linux/string.h>
#include <linux/uaccess.h>
#include <linux/nodemask.h>
#include <linux/kmemleak.h>
#include <linux/mempolicy.h>
#include <linux/mutex.h>
#include <linux/fault-inject.h>
#include <linux/rtmutex.h>
#include <linux/reciprocal_div.h>
#include <linux/debugobjects.h>
#include <linux/memory.h>
#include <linux/prefetch.h>
#include <linux/sched/task_stack.h>
#include <net/sock.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/page.h>
#include <trace/events/kmem.h>
#include "internal.h"
#include "slab.h"
/*
* DEBUG - 1 for kmem_cache_create() to honour; SLAB_RED_ZONE & SLAB_POISON.
* 0 for faster, smaller code (especially in the critical paths).
*
* STATS - 1 to collect stats for /proc/slabinfo.
* 0 for faster, smaller code (especially in the critical paths).
*
* FORCED_DEBUG - 1 enables SLAB_RED_ZONE and SLAB_POISON (if possible)
*/
#ifdef CONFIG_DEBUG_SLAB
#define DEBUG 1
#define STATS 1
#define FORCED_DEBUG 1
#else
#define DEBUG 0
#define STATS 0
#define FORCED_DEBUG 0
#endif
/* Shouldn't this be in a header file somewhere? */
#define BYTES_PER_WORD sizeof(void *)
#define REDZONE_ALIGN max(BYTES_PER_WORD, __alignof__(unsigned long long))
#ifndef ARCH_KMALLOC_FLAGS
#define ARCH_KMALLOC_FLAGS SLAB_HWCACHE_ALIGN
#endif
#define FREELIST_BYTE_INDEX (((PAGE_SIZE >> BITS_PER_BYTE) \
<= SLAB_OBJ_MIN_SIZE) ? 1 : 0)
#if FREELIST_BYTE_INDEX
typedef unsigned char freelist_idx_t;
#else
typedef unsigned short freelist_idx_t;
#endif
#define SLAB_OBJ_MAX_NUM ((1 << sizeof(freelist_idx_t) * BITS_PER_BYTE) - 1)
/*
* struct array_cache
*
* Purpose:
* - LIFO ordering, to hand out cache-warm objects from _alloc
* - reduce the number of linked list operations
* - reduce spinlock operations
*
* The limit is stored in the per-cpu structure to reduce the data cache
* footprint.
*
*/
struct array_cache {
unsigned int avail;
unsigned int limit;
unsigned int batchcount;
unsigned int touched;
void *entry[]; /*
* Must have this definition in here for the proper
* alignment of array_cache. Also simplifies accessing
* the entries.
*/
};
struct alien_cache {
spinlock_t lock;
struct array_cache ac;
};
/*
* Need this for bootstrapping a per node allocator.
*/
#define NUM_INIT_LISTS (2 * MAX_NUMNODES)
static struct kmem_cache_node __initdata init_kmem_cache_node[NUM_INIT_LISTS];
#define CACHE_CACHE 0
#define SIZE_NODE (MAX_NUMNODES)
static int drain_freelist(struct kmem_cache *cache,
struct kmem_cache_node *n, int tofree);
static void free_block(struct kmem_cache *cachep, void **objpp, int len,
int node, struct list_head *list);
static void slabs_destroy(struct kmem_cache *cachep, struct list_head *list);
static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp);
static void cache_reap(struct work_struct *unused);
static inline void fixup_objfreelist_debug(struct kmem_cache *cachep,
void **list);
static inline void fixup_slab_list(struct kmem_cache *cachep,
struct kmem_cache_node *n, struct slab *slab,
void **list);
static int slab_early_init = 1;
#define INDEX_NODE kmalloc_index(sizeof(struct kmem_cache_node))
static void kmem_cache_node_init(struct kmem_cache_node *parent)
{
INIT_LIST_HEAD(&parent->slabs_full);
INIT_LIST_HEAD(&parent->slabs_partial);
INIT_LIST_HEAD(&parent->slabs_free);
parent->total_slabs = 0;
parent->free_slabs = 0;
parent->shared = NULL;
parent->alien = NULL;
parent->colour_next = 0;
spin_lock_init(&parent->list_lock);
parent->free_objects = 0;
parent->free_touched = 0;
}
#define MAKE_LIST(cachep, listp, slab, nodeid) \
do { \
INIT_LIST_HEAD(listp); \
list_splice(&get_node(cachep, nodeid)->slab, listp); \
} while (0)
#define MAKE_ALL_LISTS(cachep, ptr, nodeid) \
do { \
MAKE_LIST((cachep), (&(ptr)->slabs_full), slabs_full, nodeid); \
MAKE_LIST((cachep), (&(ptr)->slabs_partial), slabs_partial, nodeid); \
MAKE_LIST((cachep), (&(ptr)->slabs_free), slabs_free, nodeid); \
} while (0)
#define CFLGS_OBJFREELIST_SLAB ((slab_flags_t __force)0x40000000U)
#define CFLGS_OFF_SLAB ((slab_flags_t __force)0x80000000U)
#define OBJFREELIST_SLAB(x) ((x)->flags & CFLGS_OBJFREELIST_SLAB)
#define OFF_SLAB(x) ((x)->flags & CFLGS_OFF_SLAB)
#define BATCHREFILL_LIMIT 16
/*
* Optimization question: fewer reaps means less probability for unnecessary
* cpucache drain/refill cycles.
*
* OTOH the cpuarrays can contain lots of objects,
* which could lock up otherwise freeable slabs.
*/
#define REAPTIMEOUT_AC (2*HZ)
#define REAPTIMEOUT_NODE (4*HZ)
#if STATS
#define STATS_INC_ACTIVE(x) ((x)->num_active++)
#define STATS_DEC_ACTIVE(x) ((x)->num_active--)
#define STATS_INC_ALLOCED(x) ((x)->num_allocations++)
#define STATS_INC_GROWN(x) ((x)->grown++)
#define STATS_ADD_REAPED(x, y) ((x)->reaped += (y))
#define STATS_SET_HIGH(x) \
do { \
if ((x)->num_active > (x)->high_mark) \
(x)->high_mark = (x)->num_active; \
} while (0)
#define STATS_INC_ERR(x) ((x)->errors++)
#define STATS_INC_NODEALLOCS(x) ((x)->node_allocs++)
#define STATS_INC_NODEFREES(x) ((x)->node_frees++)
#define STATS_INC_ACOVERFLOW(x) ((x)->node_overflow++)
#define STATS_SET_FREEABLE(x, i) \
do { \
if ((x)->max_freeable < i) \
(x)->max_freeable = i; \
} while (0)
#define STATS_INC_ALLOCHIT(x) atomic_inc(&(x)->allochit)
#define STATS_INC_ALLOCMISS(x) atomic_inc(&(x)->allocmiss)
#define STATS_INC_FREEHIT(x) atomic_inc(&(x)->freehit)
#define STATS_INC_FREEMISS(x) atomic_inc(&(x)->freemiss)
#else
#define STATS_INC_ACTIVE(x) do { } while (0)
#define STATS_DEC_ACTIVE(x) do { } while (0)
#define STATS_INC_ALLOCED(x) do { } while (0)
#define STATS_INC_GROWN(x) do { } while (0)
#define STATS_ADD_REAPED(x, y) do { (void)(y); } while (0)
#define STATS_SET_HIGH(x) do { } while (0)
#define STATS_INC_ERR(x) do { } while (0)
#define STATS_INC_NODEALLOCS(x) do { } while (0)
#define STATS_INC_NODEFREES(x) do { } while (0)
#define STATS_INC_ACOVERFLOW(x) do { } while (0)
#define STATS_SET_FREEABLE(x, i) do { } while (0)
#define STATS_INC_ALLOCHIT(x) do { } while (0)
#define STATS_INC_ALLOCMISS(x) do { } while (0)
#define STATS_INC_FREEHIT(x) do { } while (0)
#define STATS_INC_FREEMISS(x) do { } while (0)
#endif
#if DEBUG
/*
* memory layout of objects:
* 0 : objp
* 0 .. cachep->obj_offset - BYTES_PER_WORD - 1: padding. This ensures that
* the end of an object is aligned with the end of the real
* allocation. Catches writes behind the end of the allocation.
* cachep->obj_offset - BYTES_PER_WORD .. cachep->obj_offset - 1:
* redzone word.
* cachep->obj_offset: The real object.
* cachep->size - 2* BYTES_PER_WORD: redzone word [BYTES_PER_WORD long]
* cachep->size - 1* BYTES_PER_WORD: last caller address
* [BYTES_PER_WORD long]
*/
static int obj_offset(struct kmem_cache *cachep)
{
return cachep->obj_offset;
}
static unsigned long long *dbg_redzone1(struct kmem_cache *cachep, void *objp)
{
BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
return (unsigned long long *) (objp + obj_offset(cachep) -
sizeof(unsigned long long));
}
static unsigned long long *dbg_redzone2(struct kmem_cache *cachep, void *objp)
{
BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
if (cachep->flags & SLAB_STORE_USER)
return (unsigned long long *)(objp + cachep->size -
sizeof(unsigned long long) -
REDZONE_ALIGN);
return (unsigned long long *) (objp + cachep->size -
sizeof(unsigned long long));
}
static void **dbg_userword(struct kmem_cache *cachep, void *objp)
{
BUG_ON(!(cachep->flags & SLAB_STORE_USER));
return (void **)(objp + cachep->size - BYTES_PER_WORD);
}
#else
#define obj_offset(x) 0
#define dbg_redzone1(cachep, objp) ({BUG(); (unsigned long long *)NULL;})
#define dbg_redzone2(cachep, objp) ({BUG(); (unsigned long long *)NULL;})
#define dbg_userword(cachep, objp) ({BUG(); (void **)NULL;})
#endif
/*
* Do not go above this order unless 0 objects fit into the slab or
* overridden on the command line.
*/
#define SLAB_MAX_ORDER_HI 1
#define SLAB_MAX_ORDER_LO 0
static int slab_max_order = SLAB_MAX_ORDER_LO;
static bool slab_max_order_set __initdata;
static inline void *index_to_obj(struct kmem_cache *cache,
const struct slab *slab, unsigned int idx)
{
return slab->s_mem + cache->size * idx;
}
#define BOOT_CPUCACHE_ENTRIES 1
/* internal cache of cache description objs */
static struct kmem_cache kmem_cache_boot = {
.batchcount = 1,
.limit = BOOT_CPUCACHE_ENTRIES,
.shared = 1,
.size = sizeof(struct kmem_cache),
.name = "kmem_cache",
};
static DEFINE_PER_CPU(struct delayed_work, slab_reap_work);
static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
{
return this_cpu_ptr(cachep->cpu_cache);
}
/*
* Calculate the number of objects and left-over bytes for a given buffer size.
*/
static unsigned int cache_estimate(unsigned long gfporder, size_t buffer_size,
slab_flags_t flags, size_t *left_over)
{
unsigned int num;
size_t slab_size = PAGE_SIZE << gfporder;
/*
* The slab management structure can be either off the slab or
* on it. For the latter case, the memory allocated for a
* slab is used for:
*
* - @buffer_size bytes for each object
* - One freelist_idx_t for each object
*
* We don't need to consider alignment of freelist because
* freelist will be at the end of slab page. The objects will be
* at the correct alignment.
*
* If the slab management structure is off the slab, then the
* alignment will already be calculated into the size. Because
* the slabs are all pages aligned, the objects will be at the
* correct alignment when allocated.
*/
if (flags & (CFLGS_OBJFREELIST_SLAB | CFLGS_OFF_SLAB)) {
num = slab_size / buffer_size;
*left_over = slab_size % buffer_size;
} else {
num = slab_size / (buffer_size + sizeof(freelist_idx_t));
*left_over = slab_size %
(buffer_size + sizeof(freelist_idx_t));
}
return num;
}
#if DEBUG
#define slab_error(cachep, msg) __slab_error(__func__, cachep, msg)
static void __slab_error(const char *function, struct kmem_cache *cachep,
char *msg)
{
pr_err("slab error in %s(): cache `%s': %s\n",
function, cachep->name, msg);
dump_stack();
add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
}
#endif
/*
* By default on NUMA we use alien caches to stage the freeing of
* objects allocated from other nodes. This causes massive memory
* inefficiencies when using fake NUMA setup to split memory into a
* large number of small nodes, so it can be disabled on the command
* line
*/
static int use_alien_caches __read_mostly = 1;
static int __init noaliencache_setup(char *s)
{
use_alien_caches = 0;
return 1;
}
__setup("noaliencache", noaliencache_setup);
static int __init slab_max_order_setup(char *str)
{
get_option(&str, &slab_max_order);
slab_max_order = slab_max_order < 0 ? 0 :
min(slab_max_order, MAX_ORDER - 1);
slab_max_order_set = true;
return 1;
}
__setup("slab_max_order=", slab_max_order_setup);
#ifdef CONFIG_NUMA
/*
* Special reaping functions for NUMA systems called from cache_reap().
* These take care of doing round robin flushing of alien caches (containing
* objects freed on different nodes from which they were allocated) and the
* flushing of remote pcps by calling drain_node_pages.
*/
static DEFINE_PER_CPU(unsigned long, slab_reap_node);
static void init_reap_node(int cpu)
{
per_cpu(slab_reap_node, cpu) = next_node_in(cpu_to_mem(cpu),
node_online_map);
}
static void next_reap_node(void)
{
int node = __this_cpu_read(slab_reap_node);
node = next_node_in(node, node_online_map);
__this_cpu_write(slab_reap_node, node);
}
#else
#define init_reap_node(cpu) do { } while (0)
#define next_reap_node(void) do { } while (0)
#endif
/*
* Initiate the reap timer running on the target CPU. We run at around 1 to 2Hz
* via the workqueue/eventd.
* Add the CPU number into the expiration time to minimize the possibility of
* the CPUs getting into lockstep and contending for the global cache chain
* lock.
*/
static void start_cpu_timer(int cpu)
{
struct delayed_work *reap_work = &per_cpu(slab_reap_work, cpu);
if (reap_work->work.func == NULL) {
init_reap_node(cpu);
INIT_DEFERRABLE_WORK(reap_work, cache_reap);
schedule_delayed_work_on(cpu, reap_work,
__round_jiffies_relative(HZ, cpu));
}
}
static void init_arraycache(struct array_cache *ac, int limit, int batch)
{
if (ac) {
ac->avail = 0;
ac->limit = limit;
ac->batchcount = batch;
ac->touched = 0;
}
}
static struct array_cache *alloc_arraycache(int node, int entries,
int batchcount, gfp_t gfp)
{
size_t memsize = sizeof(void *) * entries + sizeof(struct array_cache);
struct array_cache *ac = NULL;
ac = kmalloc_node(memsize, gfp, node);
/*
* The array_cache structures contain pointers to free object.
* However, when such objects are allocated or transferred to another
* cache the pointers are not cleared and they could be counted as
* valid references during a kmemleak scan. Therefore, kmemleak must
* not scan such objects.
*/
kmemleak_no_scan(ac);
init_arraycache(ac, entries, batchcount);
return ac;
}
static noinline void cache_free_pfmemalloc(struct kmem_cache *cachep,
struct slab *slab, void *objp)
{
struct kmem_cache_node *n;
int slab_node;
LIST_HEAD(list);
slab_node = slab_nid(slab);
n = get_node(cachep, slab_node);
spin_lock(&n->list_lock);
free_block(cachep, &objp, 1, slab_node, &list);
spin_unlock(&n->list_lock);
slabs_destroy(cachep, &list);
}
/*
* Transfer objects in one arraycache to another.
* Locking must be handled by the caller.
*
* Return the number of entries transferred.
*/
static int transfer_objects(struct array_cache *to,
struct array_cache *from, unsigned int max)
{
/* Figure out how many entries to transfer */
int nr = min3(from->avail, max, to->limit - to->avail);
if (!nr)
return 0;
memcpy(to->entry + to->avail, from->entry + from->avail - nr,
sizeof(void *) *nr);
from->avail -= nr;
to->avail += nr;
return nr;
}
/* &alien->lock must be held by alien callers. */
static __always_inline void __free_one(struct array_cache *ac, void *objp)
{
/* Avoid trivial double-free. */
if (IS_ENABLED(CONFIG_SLAB_FREELIST_HARDENED) &&
WARN_ON_ONCE(ac->avail > 0 && ac->entry[ac->avail - 1] == objp))
return;
ac->entry[ac->avail++] = objp;
}
#ifndef CONFIG_NUMA
#define drain_alien_cache(cachep, alien) do { } while (0)
#define reap_alien(cachep, n) do { } while (0)
static inline struct alien_cache **alloc_alien_cache(int node,
int limit, gfp_t gfp)
{
return NULL;
}
static inline void free_alien_cache(struct alien_cache **ac_ptr)
{
}
static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
{
return 0;
}
static inline gfp_t gfp_exact_node(gfp_t flags)
{
return flags & ~__GFP_NOFAIL;
}
#else /* CONFIG_NUMA */
static struct alien_cache *__alloc_alien_cache(int node, int entries,
int batch, gfp_t gfp)
{
size_t memsize = sizeof(void *) * entries + sizeof(struct alien_cache);
struct alien_cache *alc = NULL;
alc = kmalloc_node(memsize, gfp, node);
if (alc) {
kmemleak_no_scan(alc);
init_arraycache(&alc->ac, entries, batch);
spin_lock_init(&alc->lock);
}
return alc;
}
static struct alien_cache **alloc_alien_cache(int node, int limit, gfp_t gfp)
{
struct alien_cache **alc_ptr;
int i;
if (limit > 1)
limit = 12;
alc_ptr = kcalloc_node(nr_node_ids, sizeof(void *), gfp, node);
if (!alc_ptr)
return NULL;
for_each_node(i) {
if (i == node || !node_online(i))
continue;
alc_ptr[i] = __alloc_alien_cache(node, limit, 0xbaadf00d, gfp);
if (!alc_ptr[i]) {
for (i--; i >= 0; i--)
kfree(alc_ptr[i]);
kfree(alc_ptr);
return NULL;
}
}
return alc_ptr;
}
static void free_alien_cache(struct alien_cache **alc_ptr)
{
int i;
if (!alc_ptr)
return;
for_each_node(i)
kfree(alc_ptr[i]);
kfree(alc_ptr);
}
static void __drain_alien_cache(struct kmem_cache *cachep,
struct array_cache *ac, int node,
struct list_head *list)
{
struct kmem_cache_node *n = get_node(cachep, node);
if (ac->avail) {
spin_lock(&n->list_lock);
/*
* Stuff objects into the remote nodes shared array first.
* That way we could avoid the overhead of putting the objects
* into the free lists and getting them back later.
*/
if (n->shared)
transfer_objects(n->shared, ac, ac->limit);
free_block(cachep, ac->entry, ac->avail, node, list);
ac->avail = 0;
spin_unlock(&n->list_lock);
}
}
/*
* Called from cache_reap() to regularly drain alien caches round robin.
*/
static void reap_alien(struct kmem_cache *cachep, struct kmem_cache_node *n)
{
int node = __this_cpu_read(slab_reap_node);
if (n->alien) {
struct alien_cache *alc = n->alien[node];
struct array_cache *ac;
if (alc) {
ac = &alc->ac;
if (ac->avail && spin_trylock_irq(&alc->lock)) {
LIST_HEAD(list);
__drain_alien_cache(cachep, ac, node, &list);
spin_unlock_irq(&alc->lock);
slabs_destroy(cachep, &list);
}
}
}
}
static void drain_alien_cache(struct kmem_cache *cachep,
struct alien_cache **alien)
{
int i = 0;
struct alien_cache *alc;
struct array_cache *ac;
unsigned long flags;
for_each_online_node(i) {
alc = alien[i];
if (alc) {
LIST_HEAD(list);
ac = &alc->ac;
spin_lock_irqsave(&alc->lock, flags);
__drain_alien_cache(cachep, ac, i, &list);
spin_unlock_irqrestore(&alc->lock, flags);
slabs_destroy(cachep, &list);
}
}
}
static int __cache_free_alien(struct kmem_cache *cachep, void *objp,
int node, int slab_node)
{
struct kmem_cache_node *n;
struct alien_cache *alien = NULL;
struct array_cache *ac;
LIST_HEAD(list);
n = get_node(cachep, node);
STATS_INC_NODEFREES(cachep);
if (n->alien && n->alien[slab_node]) {
alien = n->alien[slab_node];
ac = &alien->ac;
spin_lock(&alien->lock);
if (unlikely(ac->avail == ac->limit)) {
STATS_INC_ACOVERFLOW(cachep);
__drain_alien_cache(cachep, ac, slab_node, &list);
}
__free_one(ac, objp);
spin_unlock(&alien->lock);
slabs_destroy(cachep, &list);
} else {
n = get_node(cachep, slab_node);
spin_lock(&n->list_lock);
free_block(cachep, &objp, 1, slab_node, &list);
spin_unlock(&n->list_lock);
slabs_destroy(cachep, &list);
}
return 1;
}
static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
{
int slab_node = slab_nid(virt_to_slab(objp));
int node = numa_mem_id();
/*
* Make sure we are not freeing an object from another node to the array
* cache on this cpu.
*/
if (likely(node == slab_node))
return 0;
return __cache_free_alien(cachep, objp, node, slab_node);
}
/*
* Construct gfp mask to allocate from a specific node but do not reclaim or
* warn about failures.
*/
static inline gfp_t gfp_exact_node(gfp_t flags)
{
return (flags | __GFP_THISNODE | __GFP_NOWARN) & ~(__GFP_RECLAIM|__GFP_NOFAIL);
}
#endif
static int init_cache_node(struct kmem_cache *cachep, int node, gfp_t gfp)
{
struct kmem_cache_node *n;
/*
* Set up the kmem_cache_node for cpu before we can
* begin anything. Make sure some other cpu on this
* node has not already allocated this
*/
n = get_node(cachep, node);
if (n) {
spin_lock_irq(&n->list_lock);
n->free_limit = (1 + nr_cpus_node(node)) * cachep->batchcount +
cachep->num;
spin_unlock_irq(&n->list_lock);
return 0;
}
n = kmalloc_node(sizeof(struct kmem_cache_node), gfp, node);
if (!n)
return -ENOMEM;
kmem_cache_node_init(n);
n->next_reap = jiffies + REAPTIMEOUT_NODE +
((unsigned long)cachep) % REAPTIMEOUT_NODE;
n->free_limit =
(1 + nr_cpus_node(node)) * cachep->batchcount + cachep->num;
/*
* The kmem_cache_nodes don't come and go as CPUs
* come and go. slab_mutex provides sufficient
* protection here.
*/
cachep->node[node] = n;
return 0;
}
#if (defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG)) || defined(CONFIG_SMP)
/*
* Allocates and initializes node for a node on each slab cache, used for
* either memory or cpu hotplug. If memory is being hot-added, the kmem_cache_node
* will be allocated off-node since memory is not yet online for the new node.
* When hotplugging memory or a cpu, existing nodes are not replaced if
* already in use.
*
* Must hold slab_mutex.
*/
static int init_cache_node_node(int node)
{
int ret;
struct kmem_cache *cachep;
list_for_each_entry(cachep, &slab_caches, list) {
ret = init_cache_node(cachep, node, GFP_KERNEL);
if (ret)
return ret;
}
return 0;
}
#endif
static int setup_kmem_cache_node(struct kmem_cache *cachep,
int node, gfp_t gfp, bool force_change)
{
int ret = -ENOMEM;
struct kmem_cache_node *n;
struct array_cache *old_shared = NULL;
struct array_cache *new_shared = NULL;
struct alien_cache **new_alien = NULL;
LIST_HEAD(list);
if (use_alien_caches) {
new_alien = alloc_alien_cache(node, cachep->limit, gfp);
if (!new_alien)
goto fail;
}
if (cachep->shared) {
new_shared = alloc_arraycache(node,
cachep->shared * cachep->batchcount, 0xbaadf00d, gfp);
if (!new_shared)
goto fail;
}
ret = init_cache_node(cachep, node, gfp);
if (ret)
goto fail;
n = get_node(cachep, node);
spin_lock_irq(&n->list_lock);
if (n->shared && force_change) {
free_block(cachep, n->shared->entry,
n->shared->avail, node, &list);
n->shared->avail = 0;
}
if (!n->shared || force_change) {
old_shared = n->shared;
n->shared = new_shared;
new_shared = NULL;
}
if (!n->alien) {
n->alien = new_alien;
new_alien = NULL;
}
spin_unlock_irq(&n->list_lock);
slabs_destroy(cachep, &list);
/*
* To protect lockless access to n->shared during irq disabled context.
* If n->shared isn't NULL in irq disabled context, accessing to it is
* guaranteed to be valid until irq is re-enabled, because it will be
* freed after synchronize_rcu().
*/
if (old_shared && force_change)
synchronize_rcu();
fail:
kfree(old_shared);
kfree(new_shared);
free_alien_cache(new_alien);
return ret;
}
#ifdef CONFIG_SMP
static void cpuup_canceled(long cpu)
{
struct kmem_cache *cachep;
struct kmem_cache_node *n = NULL;
int node = cpu_to_mem(cpu);
const struct cpumask *mask = cpumask_of_node(node);
list_for_each_entry(cachep, &slab_caches, list) {
struct array_cache *nc;
struct array_cache *shared;
struct alien_cache **alien;
LIST_HEAD(list);
n = get_node(cachep, node);
if (!n)
continue;
spin_lock_irq(&n->list_lock);
/* Free limit for this kmem_cache_node */
n->free_limit -= cachep->batchcount;
/* cpu is dead; no one can alloc from it. */
nc = per_cpu_ptr(cachep->cpu_cache, cpu);
free_block(cachep, nc->entry, nc->avail, node, &list);
nc->avail = 0;
if (!cpumask_empty(mask)) {
spin_unlock_irq(&n->list_lock);
goto free_slab;
}
shared = n->shared;
if (shared) {
free_block(cachep, shared->entry,
shared->avail, node, &list);
n->shared = NULL;
}
alien = n->alien;
n->alien = NULL;
spin_unlock_irq(&n->list_lock);
kfree(shared);
if (alien) {
drain_alien_cache(cachep, alien);
free_alien_cache(alien);
}
free_slab:
slabs_destroy(cachep, &list);
}
/*
* In the previous loop, all the objects were freed to
* the respective cache's slabs, now we can go ahead and
* shrink each nodelist to its limit.
*/
list_for_each_entry(cachep, &slab_caches, list) {
n = get_node(cachep, node);
if (!n)
continue;
drain_freelist(cachep, n, INT_MAX);
}
}
static int cpuup_prepare(long cpu)
{
struct kmem_cache *cachep;
int node = cpu_to_mem(cpu);
int err;
/*
* We need to do this right in the beginning since
* alloc_arraycache's are going to use this list.
* kmalloc_node allows us to add the slab to the right
* kmem_cache_node and not this cpu's kmem_cache_node
*/
err = init_cache_node_node(node);
if (err < 0)
goto bad;
/*
* Now we can go ahead with allocating the shared arrays and
* array caches
*/
list_for_each_entry(cachep, &slab_caches, list) {
err = setup_kmem_cache_node(cachep, node, GFP_KERNEL, false);
if (err)
goto bad;
}
return 0;
bad:
cpuup_canceled(cpu);
return -ENOMEM;
}
int slab_prepare_cpu(unsigned int cpu)
{
int err;
mutex_lock(&slab_mutex);
err = cpuup_prepare(cpu);
mutex_unlock(&slab_mutex);
return err;
}
/*
* This is called for a failed online attempt and for a successful
* offline.
*
* Even if all the cpus of a node are down, we don't free the
* kmem_cache_node of any cache. This is to avoid a race between cpu_down, and
* a kmalloc allocation from another cpu for memory from the node of
* the cpu going down. The kmem_cache_node structure is usually allocated from
* kmem_cache_create() and gets destroyed at kmem_cache_destroy().
*/
int slab_dead_cpu(unsigned int cpu)
{
mutex_lock(&slab_mutex);
cpuup_canceled(cpu);
mutex_unlock(&slab_mutex);
return 0;
}
#endif
static int slab_online_cpu(unsigned int cpu)
{
start_cpu_timer(cpu);
return 0;
}
static int slab_offline_cpu(unsigned int cpu)
{
/*
* Shutdown cache reaper. Note that the slab_mutex is held so
* that if cache_reap() is invoked it cannot do anything
* expensive but will only modify reap_work and reschedule the
* timer.
*/
cancel_delayed_work_sync(&per_cpu(slab_reap_work, cpu));
/* Now the cache_reaper is guaranteed to be not running. */
per_cpu(slab_reap_work, cpu).work.func = NULL;
return 0;
}
#if defined(CONFIG_NUMA)
/*
* Drains freelist for a node on each slab cache, used for memory hot-remove.
* Returns -EBUSY if all objects cannot be drained so that the node is not
* removed.
*
* Must hold slab_mutex.
*/
static int __meminit drain_cache_node_node(int node)
{
struct kmem_cache *cachep;
int ret = 0;
list_for_each_entry(cachep, &slab_caches, list) {
struct kmem_cache_node *n;
n = get_node(cachep, node);
if (!n)
continue;
drain_freelist(cachep, n, INT_MAX);
if (!list_empty(&n->slabs_full) ||
!list_empty(&n->slabs_partial)) {
ret = -EBUSY;
break;
}
}
return ret;
}
static int __meminit slab_memory_callback(struct notifier_block *self,
unsigned long action, void *arg)
{
struct memory_notify *mnb = arg;
int ret = 0;
int nid;
nid = mnb->status_change_nid;
if (nid < 0)
goto out;
switch (action) {
case MEM_GOING_ONLINE:
mutex_lock(&slab_mutex);
ret = init_cache_node_node(nid);
mutex_unlock(&slab_mutex);
break;
case MEM_GOING_OFFLINE:
mutex_lock(&slab_mutex);
ret = drain_cache_node_node(nid);
mutex_unlock(&slab_mutex);
break;
case MEM_ONLINE:
case MEM_OFFLINE:
case MEM_CANCEL_ONLINE:
case MEM_CANCEL_OFFLINE:
break;
}
out:
return notifier_from_errno(ret);
}
#endif /* CONFIG_NUMA */
/*
* swap the static kmem_cache_node with kmalloced memory
*/
static void __init init_list(struct kmem_cache *cachep, struct kmem_cache_node *list,
int nodeid)
{
struct kmem_cache_node *ptr;
ptr = kmalloc_node(sizeof(struct kmem_cache_node), GFP_NOWAIT, nodeid);
BUG_ON(!ptr);
memcpy(ptr, list, sizeof(struct kmem_cache_node));
/*
* Do not assume that spinlocks can be initialized via memcpy:
*/
spin_lock_init(&ptr->list_lock);
MAKE_ALL_LISTS(cachep, ptr, nodeid);
cachep->node[nodeid] = ptr;
}
/*
* For setting up all the kmem_cache_node for cache whose buffer_size is same as
* size of kmem_cache_node.
*/
static void __init set_up_node(struct kmem_cache *cachep, int index)
{
int node;
for_each_online_node(node) {
cachep->node[node] = &init_kmem_cache_node[index + node];
cachep->node[node]->next_reap = jiffies +
REAPTIMEOUT_NODE +
((unsigned long)cachep) % REAPTIMEOUT_NODE;
}
}
/*
* Initialisation. Called after the page allocator have been initialised and
* before smp_init().
*/
void __init kmem_cache_init(void)
{
int i;
kmem_cache = &kmem_cache_boot;
if (!IS_ENABLED(CONFIG_NUMA) || num_possible_nodes() == 1)
use_alien_caches = 0;
for (i = 0; i < NUM_INIT_LISTS; i++)
kmem_cache_node_init(&init_kmem_cache_node[i]);
/*
* Fragmentation resistance on low memory - only use bigger
* page orders on machines with more than 32MB of memory if
* not overridden on the command line.
*/
if (!slab_max_order_set && totalram_pages() > (32 << 20) >> PAGE_SHIFT)
slab_max_order = SLAB_MAX_ORDER_HI;
/* Bootstrap is tricky, because several objects are allocated
* from caches that do not exist yet:
* 1) initialize the kmem_cache cache: it contains the struct
* kmem_cache structures of all caches, except kmem_cache itself:
* kmem_cache is statically allocated.
* Initially an __init data area is used for the head array and the
* kmem_cache_node structures, it's replaced with a kmalloc allocated
* array at the end of the bootstrap.
* 2) Create the first kmalloc cache.
* The struct kmem_cache for the new cache is allocated normally.
* An __init data area is used for the head array.
* 3) Create the remaining kmalloc caches, with minimally sized
* head arrays.
* 4) Replace the __init data head arrays for kmem_cache and the first
* kmalloc cache with kmalloc allocated arrays.
* 5) Replace the __init data for kmem_cache_node for kmem_cache and
* the other cache's with kmalloc allocated memory.
* 6) Resize the head arrays of the kmalloc caches to their final sizes.
*/
/* 1) create the kmem_cache */
/*
* struct kmem_cache size depends on nr_node_ids & nr_cpu_ids
*/
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);
list_add(&kmem_cache->list, &slab_caches);
slab_state = PARTIAL;
/*
* Initialize the caches that provide memory for the kmem_cache_node
* structures first. Without this, further allocations will bug.
*/
kmalloc_caches[KMALLOC_NORMAL][INDEX_NODE] = create_kmalloc_cache(
kmalloc_info[INDEX_NODE].name[KMALLOC_NORMAL],
kmalloc_info[INDEX_NODE].size,
ARCH_KMALLOC_FLAGS, 0,
kmalloc_info[INDEX_NODE].size);
slab_state = PARTIAL_NODE;
setup_kmalloc_cache_index_table();
slab_early_init = 0;
/* 5) Replace the bootstrap kmem_cache_node */
{
int nid;
for_each_online_node(nid) {
init_list(kmem_cache, &init_kmem_cache_node[CACHE_CACHE + nid], nid);
init_list(kmalloc_caches[KMALLOC_NORMAL][INDEX_NODE],
&init_kmem_cache_node[SIZE_NODE + nid], nid);
}
}
create_kmalloc_caches(ARCH_KMALLOC_FLAGS);
}
void __init kmem_cache_init_late(void)
{
struct kmem_cache *cachep;
/* 6) resize the head arrays to their final sizes */
mutex_lock(&slab_mutex);
list_for_each_entry(cachep, &slab_caches, list)
if (enable_cpucache(cachep, GFP_NOWAIT))
BUG();
mutex_unlock(&slab_mutex);
/* Done! */
slab_state = FULL;
#ifdef CONFIG_NUMA
/*
* Register a memory hotplug callback that initializes and frees
* node.
*/
hotplug_memory_notifier(slab_memory_callback, SLAB_CALLBACK_PRI);
#endif
/*
* The reap timers are started later, with a module init call: That part
* of the kernel is not yet operational.
*/
}
static int __init cpucache_init(void)
{
int ret;
/*
* Register the timers that return unneeded pages to the page allocator
*/
ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "SLAB online",
slab_online_cpu, slab_offline_cpu);
WARN_ON(ret < 0);
return 0;
}
__initcall(cpucache_init);
static noinline void
slab_out_of_memory(struct kmem_cache *cachep, gfp_t gfpflags, int nodeid)
{
#if DEBUG
struct kmem_cache_node *n;
unsigned long flags;
int node;
static DEFINE_RATELIMIT_STATE(slab_oom_rs, DEFAULT_RATELIMIT_INTERVAL,
DEFAULT_RATELIMIT_BURST);
if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slab_oom_rs))
return;
pr_warn("SLAB: Unable to allocate memory on node %d, gfp=%#x(%pGg)\n",
nodeid, gfpflags, &gfpflags);
pr_warn(" cache: %s, object size: %d, order: %d\n",
cachep->name, cachep->size, cachep->gfporder);
for_each_kmem_cache_node(cachep, node, n) {
unsigned long total_slabs, free_slabs, free_objs;
spin_lock_irqsave(&n->list_lock, flags);
total_slabs = n->total_slabs;
free_slabs = n->free_slabs;
free_objs = n->free_objects;
spin_unlock_irqrestore(&n->list_lock, flags);
pr_warn(" node %d: slabs: %ld/%ld, objs: %ld/%ld\n",
node, total_slabs - free_slabs, total_slabs,
(total_slabs * cachep->num) - free_objs,
total_slabs * cachep->num);
}
#endif
}
/*
* Interface to system's page allocator. No need to hold the
* kmem_cache_node ->list_lock.
*
* If we requested dmaable memory, we will get it. Even if we
* did not request dmaable memory, we might get it, but that
* would be relatively rare and ignorable.
*/
static struct slab *kmem_getpages(struct kmem_cache *cachep, gfp_t flags,
int nodeid)
{
struct folio *folio;
struct slab *slab;
flags |= cachep->allocflags;
folio = (struct folio *) __alloc_pages_node(nodeid, flags, cachep->gfporder);
if (!folio) {
slab_out_of_memory(cachep, flags, nodeid);
return NULL;
}
slab = folio_slab(folio);
account_slab(slab, cachep->gfporder, cachep, flags);
__folio_set_slab(folio);
/* Record if ALLOC_NO_WATERMARKS was set when allocating the slab */
if (sk_memalloc_socks() && page_is_pfmemalloc(folio_page(folio, 0)))
slab_set_pfmemalloc(slab);
return slab;
}
/*
* Interface to system's page release.
*/
static void kmem_freepages(struct kmem_cache *cachep, struct slab *slab)
{
int order = cachep->gfporder;
struct folio *folio = slab_folio(slab);
BUG_ON(!folio_test_slab(folio));
__slab_clear_pfmemalloc(slab);
__folio_clear_slab(folio);
page_mapcount_reset(folio_page(folio, 0));
folio->mapping = NULL;
if (current->reclaim_state)
current->reclaim_state->reclaimed_slab += 1 << order;
unaccount_slab(slab, order, cachep);
__free_pages(folio_page(folio, 0), order);
}
static void kmem_rcu_free(struct rcu_head *head)
{
struct kmem_cache *cachep;
struct slab *slab;
slab = container_of(head, struct slab, rcu_head);
cachep = slab->slab_cache;
kmem_freepages(cachep, slab);
}
#if DEBUG
static bool is_debug_pagealloc_cache(struct kmem_cache *cachep)
{
if (debug_pagealloc_enabled_static() && OFF_SLAB(cachep) &&
(cachep->size % PAGE_SIZE) == 0)
return true;
return false;
}
#ifdef CONFIG_DEBUG_PAGEALLOC
static void slab_kernel_map(struct kmem_cache *cachep, void *objp, int map)
{
if (!is_debug_pagealloc_cache(cachep))
return;
__kernel_map_pages(virt_to_page(objp), cachep->size / PAGE_SIZE, map);
}
#else
static inline void slab_kernel_map(struct kmem_cache *cachep, void *objp,
int map) {}
#endif
static void poison_obj(struct kmem_cache *cachep, void *addr, unsigned char val)
{
int size = cachep->object_size;
addr = &((char *)addr)[obj_offset(cachep)];
memset(addr, val, size);
*(unsigned char *)(addr + size - 1) = POISON_END;
}
static void dump_line(char *data, int offset, int limit)
{
int i;
unsigned char error = 0;
int bad_count = 0;
pr_err("%03x: ", offset);
for (i = 0; i < limit; i++) {
if (data[offset + i] != POISON_FREE) {
error = data[offset + i];
bad_count++;
}
}
print_hex_dump(KERN_CONT, "", 0, 16, 1,
&data[offset], limit, 1);
if (bad_count == 1) {
error ^= POISON_FREE;
if (!(error & (error - 1))) {
pr_err("Single bit error detected. Probably bad RAM.\n");
#ifdef CONFIG_X86
pr_err("Run memtest86+ or a similar memory test tool.\n");
#else
pr_err("Run a memory test tool.\n");
#endif
}
}
}
#endif
#if DEBUG
static void print_objinfo(struct kmem_cache *cachep, void *objp, int lines)
{
int i, size;
char *realobj;
if (cachep->flags & SLAB_RED_ZONE) {
pr_err("Redzone: 0x%llx/0x%llx\n",
*dbg_redzone1(cachep, objp),
*dbg_redzone2(cachep, objp));
}
if (cachep->flags & SLAB_STORE_USER)
pr_err("Last user: (%pSR)\n", *dbg_userword(cachep, objp));
realobj = (char *)objp + obj_offset(cachep);
size = cachep->object_size;
for (i = 0; i < size && lines; i += 16, lines--) {
int limit;
limit = 16;
if (i + limit > size)
limit = size - i;
dump_line(realobj, i, limit);
}
}
static void check_poison_obj(struct kmem_cache *cachep, void *objp)
{
char *realobj;
int size, i;
int lines = 0;
if (is_debug_pagealloc_cache(cachep))
return;
realobj = (char *)objp + obj_offset(cachep);
size = cachep->object_size;
for (i = 0; i < size; i++) {
char exp = POISON_FREE;
if (i == size - 1)
exp = POISON_END;
if (realobj[i] != exp) {
int limit;
/* Mismatch ! */
/* Print header */
if (lines == 0) {
pr_err("Slab corruption (%s): %s start=%px, len=%d\n",
print_tainted(), cachep->name,
realobj, size);
print_objinfo(cachep, objp, 0);
}
/* Hexdump the affected line */
i = (i / 16) * 16;
limit = 16;
if (i + limit > size)
limit = size - i;
dump_line(realobj, i, limit);
i += 16;
lines++;
/* Limit to 5 lines */
if (lines > 5)
break;
}
}
if (lines != 0) {
/* Print some data about the neighboring objects, if they
* exist:
*/
struct slab *slab = virt_to_slab(objp);
unsigned int objnr;
objnr = obj_to_index(cachep, slab, objp);
if (objnr) {
objp = index_to_obj(cachep, slab, objnr - 1);
realobj = (char *)objp + obj_offset(cachep);
pr_err("Prev obj: start=%px, len=%d\n", realobj, size);
print_objinfo(cachep, objp, 2);
}
if (objnr + 1 < cachep->num) {
objp = index_to_obj(cachep, slab, objnr + 1);
realobj = (char *)objp + obj_offset(cachep);
pr_err("Next obj: start=%px, len=%d\n", realobj, size);
print_objinfo(cachep, objp, 2);
}
}
}
#endif
#if DEBUG
static void slab_destroy_debugcheck(struct kmem_cache *cachep,
struct slab *slab)
{
int i;
if (OBJFREELIST_SLAB(cachep) && cachep->flags & SLAB_POISON) {
poison_obj(cachep, slab->freelist - obj_offset(cachep),
POISON_FREE);
}
for (i = 0; i < cachep->num; i++) {
void *objp = index_to_obj(cachep, slab, i);
if (cachep->flags & SLAB_POISON) {
check_poison_obj(cachep, objp);
slab_kernel_map(cachep, objp, 1);
}
if (cachep->flags & SLAB_RED_ZONE) {
if (*dbg_redzone1(cachep, objp) != RED_INACTIVE)
slab_error(cachep, "start of a freed object was overwritten");
if (*dbg_redzone2(cachep, objp) != RED_INACTIVE)
slab_error(cachep, "end of a freed object was overwritten");
}
}
}
#else
static void slab_destroy_debugcheck(struct kmem_cache *cachep,
struct slab *slab)
{
}
#endif
/**
* slab_destroy - destroy and release all objects in a slab
* @cachep: cache pointer being destroyed
* @slab: slab being destroyed
*
* Destroy all the objs in a slab, and release the mem back to the system.
* Before calling the slab must have been unlinked from the cache. The
* kmem_cache_node ->list_lock is not held/needed.
*/
static void slab_destroy(struct kmem_cache *cachep, struct slab *slab)
{
void *freelist;
freelist = slab->freelist;
slab_destroy_debugcheck(cachep, slab);
if (unlikely(cachep->flags & SLAB_TYPESAFE_BY_RCU))
call_rcu(&slab->rcu_head, kmem_rcu_free);
else
kmem_freepages(cachep, slab);
/*
* From now on, we don't use freelist
* although actual page can be freed in rcu context
*/
if (OFF_SLAB(cachep))
kfree(freelist);
}
/*
* Update the size of the caches before calling slabs_destroy as it may
* recursively call kfree.
*/
static void slabs_destroy(struct kmem_cache *cachep, struct list_head *list)
{
struct slab *slab, *n;
list_for_each_entry_safe(slab, n, list, slab_list) {
list_del(&slab->slab_list);
slab_destroy(cachep, slab);
}
}
/**
* calculate_slab_order - calculate size (page order) of slabs
* @cachep: pointer to the cache that is being created
* @size: size of objects to be created in this cache.
* @flags: slab allocation flags
*
* Also calculates the number of objects per slab.
*
* This could be made much more intelligent. For now, try to avoid using
* high order pages for slabs. When the gfp() functions are more friendly
* towards high-order requests, this should be changed.
*
* Return: number of left-over bytes in a slab
*/
static size_t calculate_slab_order(struct kmem_cache *cachep,
size_t size, slab_flags_t flags)
{
size_t left_over = 0;
int gfporder;
for (gfporder = 0; gfporder <= KMALLOC_MAX_ORDER; gfporder++) {
unsigned int num;
size_t remainder;
num = cache_estimate(gfporder, size, flags, &remainder);
if (!num)
continue;
/* Can't handle number of objects more than SLAB_OBJ_MAX_NUM */
if (num > SLAB_OBJ_MAX_NUM)
break;
if (flags & CFLGS_OFF_SLAB) {
struct kmem_cache *freelist_cache;
size_t freelist_size;
size_t freelist_cache_size;
freelist_size = num * sizeof(freelist_idx_t);
if (freelist_size > KMALLOC_MAX_CACHE_SIZE) {
freelist_cache_size = PAGE_SIZE << get_order(freelist_size);
} else {
freelist_cache = kmalloc_slab(freelist_size, 0u);
if (!freelist_cache)
continue;
freelist_cache_size = freelist_cache->size;
/*
* Needed to avoid possible looping condition
* in cache_grow_begin()
*/
if (OFF_SLAB(freelist_cache))
continue;
}
/* check if off slab has enough benefit */
if (freelist_cache_size > cachep->size / 2)
continue;
}
/* Found something acceptable - save it away */
cachep->num = num;
cachep->gfporder = gfporder;
left_over = remainder;
/*
* A VFS-reclaimable slab tends to have most allocations
* as GFP_NOFS and we really don't want to have to be allocating
* higher-order pages when we are unable to shrink dcache.
*/
if (flags & SLAB_RECLAIM_ACCOUNT)
break;
/*
* Large number of objects is good, but very large slabs are
* currently bad for the gfp()s.
*/
if (gfporder >= slab_max_order)
break;
/*
* Acceptable internal fragmentation?
*/
if (left_over * 8 <= (PAGE_SIZE << gfporder))
break;
}
return left_over;
}
static struct array_cache __percpu *alloc_kmem_cache_cpus(
struct kmem_cache *cachep, int entries, int batchcount)
{
int cpu;
size_t size;
struct array_cache __percpu *cpu_cache;
size = sizeof(void *) * entries + sizeof(struct array_cache);
cpu_cache = __alloc_percpu(size, sizeof(void *));
if (!cpu_cache)
return NULL;
for_each_possible_cpu(cpu) {
init_arraycache(per_cpu_ptr(cpu_cache, cpu),
entries, batchcount);
}
return cpu_cache;
}
static int __ref setup_cpu_cache(struct kmem_cache *cachep, gfp_t gfp)
{
if (slab_state >= FULL)
return enable_cpucache(cachep, gfp);
cachep->cpu_cache = alloc_kmem_cache_cpus(cachep, 1, 1);
if (!cachep->cpu_cache)
return 1;
if (slab_state == DOWN) {
/* Creation of first cache (kmem_cache). */
set_up_node(kmem_cache, CACHE_CACHE);
} else if (slab_state == PARTIAL) {
/* For kmem_cache_node */
set_up_node(cachep, SIZE_NODE);
} else {
int node;
for_each_online_node(node) {
cachep->node[node] = kmalloc_node(
sizeof(struct kmem_cache_node), gfp, node);
BUG_ON(!cachep->node[node]);
kmem_cache_node_init(cachep->node[node]);
}
}
cachep->node[numa_mem_id()]->next_reap =
jiffies + REAPTIMEOUT_NODE +
((unsigned long)cachep) % REAPTIMEOUT_NODE;
cpu_cache_get(cachep)->avail = 0;
cpu_cache_get(cachep)->limit = BOOT_CPUCACHE_ENTRIES;
cpu_cache_get(cachep)->batchcount = 1;
cpu_cache_get(cachep)->touched = 0;
cachep->batchcount = 1;
cachep->limit = BOOT_CPUCACHE_ENTRIES;
return 0;
}
slab_flags_t kmem_cache_flags(unsigned int object_size,
slab_flags_t flags, const char *name)
{
return flags;
}
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 *cachep;
cachep = find_mergeable(size, align, flags, name, ctor);
if (cachep) {
cachep->refcount++;
/*
* Adjust the object sizes so that we clear
* the complete object on kzalloc.
*/
cachep->object_size = max_t(int, cachep->object_size, size);
}
return cachep;
}
static bool set_objfreelist_slab_cache(struct kmem_cache *cachep,
size_t size, slab_flags_t flags)
{
size_t left;
cachep->num = 0;
/*
* If slab auto-initialization on free is enabled, store the freelist
* off-slab, so that its contents don't end up in one of the allocated
* objects.
*/
if (unlikely(slab_want_init_on_free(cachep)))
return false;
if (cachep->ctor || flags & SLAB_TYPESAFE_BY_RCU)
return false;
left = calculate_slab_order(cachep, size,
flags | CFLGS_OBJFREELIST_SLAB);
if (!cachep->num)
return false;
if (cachep->num * sizeof(freelist_idx_t) > cachep->object_size)
return false;
cachep->colour = left / cachep->colour_off;
return true;
}
static bool set_off_slab_cache(struct kmem_cache *cachep,
size_t size, slab_flags_t flags)
{
size_t left;
cachep->num = 0;
/*
* Always use on-slab management when SLAB_NOLEAKTRACE
* to avoid recursive calls into kmemleak.
*/
if (flags & SLAB_NOLEAKTRACE)
return false;
/*
* Size is large, assume best to place the slab management obj
* off-slab (should allow better packing of objs).
*/
left = calculate_slab_order(cachep, size, flags | CFLGS_OFF_SLAB);
if (!cachep->num)
return false;
/*
* If the slab has been placed off-slab, and we have enough space then
* move it on-slab. This is at the expense of any extra colouring.
*/
if (left >= cachep->num * sizeof(freelist_idx_t))
return false;
cachep->colour = left / cachep->colour_off;
return true;
}
static bool set_on_slab_cache(struct kmem_cache *cachep,
size_t size, slab_flags_t flags)
{
size_t left;
cachep->num = 0;
left = calculate_slab_order(cachep, size, flags);
if (!cachep->num)
return false;
cachep->colour = left / cachep->colour_off;
return true;
}
/**
* __kmem_cache_create - Create a cache.
* @cachep: cache management descriptor
* @flags: SLAB flags
*
* Returns a ptr to the cache on success, NULL on failure.
* Cannot be called within an int, but can be interrupted.
* The @ctor is run when new pages are allocated by the cache.
*
* The flags are
*
* %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
* to catch references to uninitialised memory.
*
* %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
* for buffer overruns.
*
* %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
* cacheline. This can be beneficial if you're counting cycles as closely
* as davem.
*
* Return: a pointer to the created cache or %NULL in case of error
*/
int __kmem_cache_create(struct kmem_cache *cachep, slab_flags_t flags)
{
size_t ralign = BYTES_PER_WORD;
gfp_t gfp;
int err;
unsigned int size = cachep->size;
#if DEBUG
#if FORCED_DEBUG
/*
* Enable redzoning and last user accounting, except for caches with
* large objects, if the increased size would increase the object size
* above the next power of two: caches with object sizes just above a
* power of two have a significant amount of internal fragmentation.
*/
if (size < 4096 || fls(size - 1) == fls(size-1 + REDZONE_ALIGN +
2 * sizeof(unsigned long long)))
flags |= SLAB_RED_ZONE | SLAB_STORE_USER;
if (!(flags & SLAB_TYPESAFE_BY_RCU))
flags |= SLAB_POISON;
#endif
#endif
/*
* Check that size is in terms of words. This is needed to avoid
* unaligned accesses for some archs when redzoning is used, and makes
* sure any on-slab bufctl's are also correctly aligned.
*/
size = ALIGN(size, BYTES_PER_WORD);
if (flags & SLAB_RED_ZONE) {
ralign = REDZONE_ALIGN;
/* If redzoning, ensure that the second redzone is suitably
* aligned, by adjusting the object size accordingly. */
size = ALIGN(size, REDZONE_ALIGN);
}
/* 3) caller mandated alignment */
if (ralign < cachep->align) {
ralign = cachep->align;
}
/* disable debug if necessary */
if (ralign > __alignof__(unsigned long long))
flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
/*
* 4) Store it.
*/
cachep->align = ralign;
cachep->colour_off = cache_line_size();
/* Offset must be a multiple of the alignment. */
if (cachep->colour_off < cachep->align)
cachep->colour_off = cachep->align;
if (slab_is_available())
gfp = GFP_KERNEL;
else
gfp = GFP_NOWAIT;
#if DEBUG
/*
* Both debugging options require word-alignment which is calculated
* into align above.
*/
if (flags & SLAB_RED_ZONE) {
/* add space for red zone words */
cachep->obj_offset += sizeof(unsigned long long);
size += 2 * sizeof(unsigned long long);
}
if (flags & SLAB_STORE_USER) {
/* user store requires one word storage behind the end of
* the real object. But if the second red zone needs to be
* aligned to 64 bits, we must allow that much space.
*/
if (flags & SLAB_RED_ZONE)
size += REDZONE_ALIGN;
else
size += BYTES_PER_WORD;
}
#endif
kasan_cache_create(cachep, &size, &flags);
size = ALIGN(size, cachep->align);
/*
* We should restrict the number of objects in a slab to implement
* byte sized index. Refer comment on SLAB_OBJ_MIN_SIZE definition.
*/
if (FREELIST_BYTE_INDEX && size < SLAB_OBJ_MIN_SIZE)
size = ALIGN(SLAB_OBJ_MIN_SIZE, cachep->align);
#if DEBUG
/*
* To activate debug pagealloc, off-slab management is necessary
* requirement. In early phase of initialization, small sized slab
* doesn't get initialized so it would not be possible. So, we need
* to check size >= 256. It guarantees that all necessary small
* sized slab is initialized in current slab initialization sequence.
*/
if (debug_pagealloc_enabled_static() && (flags & SLAB_POISON) &&
size >= 256 && cachep->object_size > cache_line_size()) {
if (size < PAGE_SIZE || size % PAGE_SIZE == 0) {
size_t tmp_size = ALIGN(size, PAGE_SIZE);
if (set_off_slab_cache(cachep, tmp_size, flags)) {
flags |= CFLGS_OFF_SLAB;
cachep->obj_offset += tmp_size - size;
size = tmp_size;
goto done;
}
}
}
#endif
if (set_objfreelist_slab_cache(cachep, size, flags)) {
flags |= CFLGS_OBJFREELIST_SLAB;
goto done;
}
if (set_off_slab_cache(cachep, size, flags)) {
flags |= CFLGS_OFF_SLAB;
goto done;
}
if (set_on_slab_cache(cachep, size, flags))
goto done;
return -E2BIG;
done:
cachep->freelist_size = cachep->num * sizeof(freelist_idx_t);
cachep->flags = flags;
cachep->allocflags = __GFP_COMP;
if (flags & SLAB_CACHE_DMA)
cachep->allocflags |= GFP_DMA;
if (flags & SLAB_CACHE_DMA32)
cachep->allocflags |= GFP_DMA32;
if (flags & SLAB_RECLAIM_ACCOUNT)
cachep->allocflags |= __GFP_RECLAIMABLE;
cachep->size = size;
cachep->reciprocal_buffer_size = reciprocal_value(size);
#if DEBUG
/*
* If we're going to use the generic kernel_map_pages()
* poisoning, then it's going to smash the contents of
* the redzone and userword anyhow, so switch them off.
*/
if (IS_ENABLED(CONFIG_PAGE_POISONING) &&
(cachep->flags & SLAB_POISON) &&
is_debug_pagealloc_cache(cachep))
cachep->flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
#endif
err = setup_cpu_cache(cachep, gfp);
if (err) {
__kmem_cache_release(cachep);
return err;
}
return 0;
}
#if DEBUG
static void check_irq_off(void)
{
BUG_ON(!irqs_disabled());
}
static void check_irq_on(void)
{
BUG_ON(irqs_disabled());
}
static void check_mutex_acquired(void)
{
BUG_ON(!mutex_is_locked(&slab_mutex));
}
static void check_spinlock_acquired(struct kmem_cache *cachep)
{
#ifdef CONFIG_SMP
check_irq_off();
assert_spin_locked(&get_node(cachep, numa_mem_id())->list_lock);
#endif
}
static void check_spinlock_acquired_node(struct kmem_cache *cachep, int node)
{
#ifdef CONFIG_SMP
check_irq_off();
assert_spin_locked(&get_node(cachep, node)->list_lock);
#endif
}
#else
#define check_irq_off() do { } while(0)
#define check_irq_on() do { } while(0)
#define check_mutex_acquired() do { } while(0)
#define check_spinlock_acquired(x) do { } while(0)
#define check_spinlock_acquired_node(x, y) do { } while(0)
#endif
static void drain_array_locked(struct kmem_cache *cachep, struct array_cache *ac,
int node, bool free_all, struct list_head *list)
{
int tofree;
if (!ac || !ac->avail)
return;
tofree = free_all ? ac->avail : (ac->limit + 4) / 5;
if (tofree > ac->avail)
tofree = (ac->avail + 1) / 2;
free_block(cachep, ac->entry, tofree, node, list);
ac->avail -= tofree;
memmove(ac->entry, &(ac->entry[tofree]), sizeof(void *) * ac->avail);
}
static void do_drain(void *arg)
{
struct kmem_cache *cachep = arg;
struct array_cache *ac;
int node = numa_mem_id();
struct kmem_cache_node *n;
LIST_HEAD(list);
check_irq_off();
ac = cpu_cache_get(cachep);
n = get_node(cachep, node);
spin_lock(&n->list_lock);
free_block(cachep, ac->entry, ac->avail, node, &list);
spin_unlock(&n->list_lock);
ac->avail = 0;
slabs_destroy(cachep, &list);
}
static void drain_cpu_caches(struct kmem_cache *cachep)
{
struct kmem_cache_node *n;
int node;
LIST_HEAD(list);
on_each_cpu(do_drain, cachep, 1);
check_irq_on();
for_each_kmem_cache_node(cachep, node, n)
if (n->alien)
drain_alien_cache(cachep, n->alien);
for_each_kmem_cache_node(cachep, node, n) {
spin_lock_irq(&n->list_lock);
drain_array_locked(cachep, n->shared, node, true, &list);
spin_unlock_irq(&n->list_lock);
slabs_destroy(cachep, &list);
}
}
/*
* Remove slabs from the list of free slabs.
* Specify the number of slabs to drain in tofree.
*
* Returns the actual number of slabs released.
*/
static int drain_freelist(struct kmem_cache *cache,
struct kmem_cache_node *n, int tofree)
{
struct list_head *p;
int nr_freed;
struct slab *slab;
nr_freed = 0;
while (nr_freed < tofree && !list_empty(&n->slabs_free)) {
spin_lock_irq(&n->list_lock);
p = n->slabs_free.prev;
if (p == &n->slabs_free) {
spin_unlock_irq(&n->list_lock);
goto out;
}
slab = list_entry(p, struct slab, slab_list);
list_del(&slab->slab_list);
n->free_slabs--;
n->total_slabs--;
/*
* Safe to drop the lock. The slab is no longer linked
* to the cache.
*/
n->free_objects -= cache->num;
spin_unlock_irq(&n->list_lock);
slab_destroy(cache, slab);
nr_freed++;
}
out:
return nr_freed;
}
bool __kmem_cache_empty(struct kmem_cache *s)
{
int node;
struct kmem_cache_node *n;
for_each_kmem_cache_node(s, node, n)
if (!list_empty(&n->slabs_full) ||
!list_empty(&n->slabs_partial))
return false;
return true;
}
int __kmem_cache_shrink(struct kmem_cache *cachep)
{
int ret = 0;
int node;
struct kmem_cache_node *n;
drain_cpu_caches(cachep);
check_irq_on();
for_each_kmem_cache_node(cachep, node, n) {
drain_freelist(cachep, n, INT_MAX);
ret += !list_empty(&n->slabs_full) ||
!list_empty(&n->slabs_partial);
}
return (ret ? 1 : 0);
}
int __kmem_cache_shutdown(struct kmem_cache *cachep)
{
return __kmem_cache_shrink(cachep);
}
void __kmem_cache_release(struct kmem_cache *cachep)
{
int i;
struct kmem_cache_node *n;
cache_random_seq_destroy(cachep);
free_percpu(cachep->cpu_cache);
/* NUMA: free the node structures */
for_each_kmem_cache_node(cachep, i, n) {
kfree(n->shared);
free_alien_cache(n->alien);
kfree(n);
cachep->node[i] = NULL;
}
}
/*
* Get the memory for a slab management obj.
*
* For a slab cache when the slab descriptor is off-slab, the
* slab descriptor can't come from the same cache which is being created,
* Because if it is the case, that means we defer the creation of
* the kmalloc_{dma,}_cache of size sizeof(slab descriptor) to this point.
* And we eventually call down to __kmem_cache_create(), which
* in turn looks up in the kmalloc_{dma,}_caches for the desired-size one.
* This is a "chicken-and-egg" problem.
*
* So the off-slab slab descriptor shall come from the kmalloc_{dma,}_caches,
* which are all initialized during kmem_cache_init().
*/
static void *alloc_slabmgmt(struct kmem_cache *cachep,
struct slab *slab, int colour_off,
gfp_t local_flags, int nodeid)
{
void *freelist;
void *addr = slab_address(slab);
slab->s_mem = addr + colour_off;
slab->active = 0;
if (OBJFREELIST_SLAB(cachep))
freelist = NULL;
else if (OFF_SLAB(cachep)) {
/* Slab management obj is off-slab. */
freelist = kmalloc_node(cachep->freelist_size,
local_flags, nodeid);
} else {
/* We will use last bytes at the slab for freelist */
freelist = addr + (PAGE_SIZE << cachep->gfporder) -
cachep->freelist_size;
}
return freelist;
}
static inline freelist_idx_t get_free_obj(struct slab *slab, unsigned int idx)
{
return ((freelist_idx_t *) slab->freelist)[idx];
}
static inline void set_free_obj(struct slab *slab,
unsigned int idx, freelist_idx_t val)
{
((freelist_idx_t *)(slab->freelist))[idx] = val;
}
static void cache_init_objs_debug(struct kmem_cache *cachep, struct slab *slab)
{
#if DEBUG
int i;
for (i = 0; i < cachep->num; i++) {
void *objp = index_to_obj(cachep, slab, i);
if (cachep->flags & SLAB_STORE_USER)
*dbg_userword(cachep, objp) = NULL;
if (cachep->flags & SLAB_RED_ZONE) {
*dbg_redzone1(cachep, objp) = RED_INACTIVE;
*dbg_redzone2(cachep, objp) = RED_INACTIVE;
}
/*
* Constructors are not allowed to allocate memory from the same
* cache which they are a constructor for. Otherwise, deadlock.
* They must also be threaded.
*/
if (cachep->ctor && !(cachep->flags & SLAB_POISON)) {
kasan_unpoison_object_data(cachep,
objp + obj_offset(cachep));
cachep->ctor(objp + obj_offset(cachep));
kasan_poison_object_data(
cachep, objp + obj_offset(cachep));
}
if (cachep->flags & SLAB_RED_ZONE) {
if (*dbg_redzone2(cachep, objp) != RED_INACTIVE)
slab_error(cachep, "constructor overwrote the end of an object");
if (*dbg_redzone1(cachep, objp) != RED_INACTIVE)
slab_error(cachep, "constructor overwrote the start of an object");
}
/* need to poison the objs? */
if (cachep->flags & SLAB_POISON) {
poison_obj(cachep, objp, POISON_FREE);
slab_kernel_map(cachep, objp, 0);
}
}
#endif
}
#ifdef CONFIG_SLAB_FREELIST_RANDOM
/* Hold information during a freelist initialization */
union freelist_init_state {
struct {
unsigned int pos;
unsigned int *list;
unsigned int count;
};
struct rnd_state rnd_state;
};
/*
* Initialize the state based on the randomization method available.
* return true if the pre-computed list is available, false otherwise.
*/
static bool freelist_state_initialize(union freelist_init_state *state,
struct kmem_cache *cachep,
unsigned int count)
{
bool ret;
unsigned int rand;
/* Use best entropy available to define a random shift */
rand = get_random_u32();
/* Use a random state if the pre-computed list is not available */
if (!cachep->random_seq) {
prandom_seed_state(&state->rnd_state, rand);
ret = false;
} else {
state->list = cachep->random_seq;
state->count = count;
state->pos = rand % count;
ret = true;
}
return ret;
}
/* Get the next entry on the list and randomize it using a random shift */
static freelist_idx_t next_random_slot(union freelist_init_state *state)
{
if (state->pos >= state->count)
state->pos = 0;
return state->list[state->pos++];
}
/* Swap two freelist entries */
static void swap_free_obj(struct slab *slab, unsigned int a, unsigned int b)
{
swap(((freelist_idx_t *) slab->freelist)[a],
((freelist_idx_t *) slab->freelist)[b]);
}
/*
* Shuffle the freelist initialization state based on pre-computed lists.
* return true if the list was successfully shuffled, false otherwise.
*/
static bool shuffle_freelist(struct kmem_cache *cachep, struct slab *slab)
{
unsigned int objfreelist = 0, i, rand, count = cachep->num;
union freelist_init_state state;
bool precomputed;
if (count < 2)
return false;
precomputed = freelist_state_initialize(&state, cachep, count);
/* Take a random entry as the objfreelist */
if (OBJFREELIST_SLAB(cachep)) {
if (!precomputed)
objfreelist = count - 1;
else
objfreelist = next_random_slot(&state);
slab->freelist = index_to_obj(cachep, slab, objfreelist) +
obj_offset(cachep);
count--;
}
/*
* On early boot, generate the list dynamically.
* Later use a pre-computed list for speed.
*/
if (!precomputed) {
for (i = 0; i < count; i++)
set_free_obj(slab, i, i);
/* Fisher-Yates shuffle */
for (i = count - 1; i > 0; i--) {
rand = prandom_u32_state(&state.rnd_state);
rand %= (i + 1);
swap_free_obj(slab, i, rand);
}
} else {
for (i = 0; i < count; i++)
set_free_obj(slab, i, next_random_slot(&state));
}
if (OBJFREELIST_SLAB(cachep))
set_free_obj(slab, cachep->num - 1, objfreelist);
return true;
}
#else
static inline bool shuffle_freelist(struct kmem_cache *cachep,
struct slab *slab)
{
return false;
}
#endif /* CONFIG_SLAB_FREELIST_RANDOM */
static void cache_init_objs(struct kmem_cache *cachep,
struct slab *slab)
{
int i;
void *objp;
bool shuffled;
cache_init_objs_debug(cachep, slab);
/* Try to randomize the freelist if enabled */
shuffled = shuffle_freelist(cachep, slab);
if (!shuffled && OBJFREELIST_SLAB(cachep)) {
slab->freelist = index_to_obj(cachep, slab, cachep->num - 1) +
obj_offset(cachep);
}
for (i = 0; i < cachep->num; i++) {
objp = index_to_obj(cachep, slab, i);
objp = kasan_init_slab_obj(cachep, objp);
/* constructor could break poison info */
if (DEBUG == 0 && cachep->ctor) {
kasan_unpoison_object_data(cachep, objp);
cachep->ctor(objp);
kasan_poison_object_data(cachep, objp);
}
if (!shuffled)
set_free_obj(slab, i, i);
}
}
static void *slab_get_obj(struct kmem_cache *cachep, struct slab *slab)
{
void *objp;
objp = index_to_obj(cachep, slab, get_free_obj(slab, slab->active));
slab->active++;
return objp;
}
static void slab_put_obj(struct kmem_cache *cachep,
struct slab *slab, void *objp)
{
unsigned int objnr = obj_to_index(cachep, slab, objp);
#if DEBUG
unsigned int i;
/* Verify double free bug */
for (i = slab->active; i < cachep->num; i++) {
if (get_free_obj(slab, i) == objnr) {
pr_err("slab: double free detected in cache '%s', objp %px\n",
cachep->name, objp);
BUG();
}
}
#endif
slab->active--;
if (!slab->freelist)
slab->freelist = objp + obj_offset(cachep);
set_free_obj(slab, slab->active, objnr);
}
/*
* Grow (by 1) the number of slabs within a cache. This is called by
* kmem_cache_alloc() when there are no active objs left in a cache.
*/
static struct slab *cache_grow_begin(struct kmem_cache *cachep,
gfp_t flags, int nodeid)
{
void *freelist;
size_t offset;
gfp_t local_flags;
int slab_node;
struct kmem_cache_node *n;
struct slab *slab;
/*
* Be lazy and only check for valid flags here, keeping it out of the
* critical path in kmem_cache_alloc().
*/
if (unlikely(flags & GFP_SLAB_BUG_MASK))
flags = kmalloc_fix_flags(flags);
WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO));
local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
check_irq_off();
if (gfpflags_allow_blocking(local_flags))
local_irq_enable();
/*
* Get mem for the objs. Attempt to allocate a physical page from
* 'nodeid'.
*/
slab = kmem_getpages(cachep, local_flags, nodeid);
if (!slab)
goto failed;
slab_node = slab_nid(slab);
n = get_node(cachep, slab_node);
/* Get colour for the slab, and cal the next value. */
n->colour_next++;
if (n->colour_next >= cachep->colour)
n->colour_next = 0;
offset = n->colour_next;
if (offset >= cachep->colour)
offset = 0;
offset *= cachep->colour_off;
/*
* Call kasan_poison_slab() before calling alloc_slabmgmt(), so
* page_address() in the latter returns a non-tagged pointer,
* as it should be for slab pages.
*/
kasan_poison_slab(slab);
/* Get slab management. */
freelist = alloc_slabmgmt(cachep, slab, offset,
local_flags & ~GFP_CONSTRAINT_MASK, slab_node);
if (OFF_SLAB(cachep) && !freelist)
goto opps1;
slab->slab_cache = cachep;
slab->freelist = freelist;
cache_init_objs(cachep, slab);
if (gfpflags_allow_blocking(local_flags))
local_irq_disable();
return slab;
opps1:
kmem_freepages(cachep, slab);
failed:
if (gfpflags_allow_blocking(local_flags))
local_irq_disable();
return NULL;
}
static void cache_grow_end(struct kmem_cache *cachep, struct slab *slab)
{
struct kmem_cache_node *n;
void *list = NULL;
check_irq_off();
if (!slab)
return;
INIT_LIST_HEAD(&slab->slab_list);
n = get_node(cachep, slab_nid(slab));
spin_lock(&n->list_lock);
n->total_slabs++;
if (!slab->active) {
list_add_tail(&slab->slab_list, &n->slabs_free);
n->free_slabs++;
} else
fixup_slab_list(cachep, n, slab, &list);
STATS_INC_GROWN(cachep);
n->free_objects += cachep->num - slab->active;
spin_unlock(&n->list_lock);
fixup_objfreelist_debug(cachep, &list);
}
#if DEBUG
/*
* Perform extra freeing checks:
* - detect bad pointers.
* - POISON/RED_ZONE checking
*/
static void kfree_debugcheck(const void *objp)
{
if (!virt_addr_valid(objp)) {
pr_err("kfree_debugcheck: out of range ptr %lxh\n",
(unsigned long)objp);
BUG();
}
}
static inline void verify_redzone_free(struct kmem_cache *cache, void *obj)
{
unsigned long long redzone1, redzone2;
redzone1 = *dbg_redzone1(cache, obj);
redzone2 = *dbg_redzone2(cache, obj);
/*
* Redzone is ok.
*/
if (redzone1 == RED_ACTIVE && redzone2 == RED_ACTIVE)
return;
if (redzone1 == RED_INACTIVE && redzone2 == RED_INACTIVE)
slab_error(cache, "double free detected");
else
slab_error(cache, "memory outside object was overwritten");
pr_err("%px: redzone 1:0x%llx, redzone 2:0x%llx\n",
obj, redzone1, redzone2);
}
static void *cache_free_debugcheck(struct kmem_cache *cachep, void *objp,
unsigned long caller)
{
unsigned int objnr;
struct slab *slab;
BUG_ON(virt_to_cache(objp) != cachep);
objp -= obj_offset(cachep);
kfree_debugcheck(objp);
slab = virt_to_slab(objp);
if (cachep->flags & SLAB_RED_ZONE) {
verify_redzone_free(cachep, objp);
*dbg_redzone1(cachep, objp) = RED_INACTIVE;
*dbg_redzone2(cachep, objp) = RED_INACTIVE;
}
if (cachep->flags & SLAB_STORE_USER)
*dbg_userword(cachep, objp) = (void *)caller;
objnr = obj_to_index(cachep, slab, objp);
BUG_ON(objnr >= cachep->num);
BUG_ON(objp != index_to_obj(cachep, slab, objnr));
if (cachep->flags & SLAB_POISON) {
poison_obj(cachep, objp, POISON_FREE);
slab_kernel_map(cachep, objp, 0);
}
return objp;
}
#else
#define kfree_debugcheck(x) do { } while(0)
#define cache_free_debugcheck(x, objp, z) (objp)
#endif
static inline void fixup_objfreelist_debug(struct kmem_cache *cachep,
void **list)
{
#if DEBUG
void *next = *list;
void *objp;
while (next) {
objp = next - obj_offset(cachep);
next = *(void **)next;
poison_obj(cachep, objp, POISON_FREE);
}
#endif
}
static inline void fixup_slab_list(struct kmem_cache *cachep,
struct kmem_cache_node *n, struct slab *slab,
void **list)
{
/* move slabp to correct slabp list: */
list_del(&slab->slab_list);
if (slab->active == cachep->num) {
list_add(&slab->slab_list, &n->slabs_full);
if (OBJFREELIST_SLAB(cachep)) {
#if DEBUG
/* Poisoning will be done without holding the lock */
if (cachep->flags & SLAB_POISON) {
void **objp = slab->freelist;
*objp = *list;
*list = objp;
}
#endif
slab->freelist = NULL;
}
} else
list_add(&slab->slab_list, &n->slabs_partial);
}
/* Try to find non-pfmemalloc slab if needed */
static noinline struct slab *get_valid_first_slab(struct kmem_cache_node *n,
struct slab *slab, bool pfmemalloc)
{
if (!slab)
return NULL;
if (pfmemalloc)
return slab;
if (!slab_test_pfmemalloc(slab))
return slab;
/* No need to keep pfmemalloc slab if we have enough free objects */
if (n->free_objects > n->free_limit) {
slab_clear_pfmemalloc(slab);
return slab;
}
/* Move pfmemalloc slab to the end of list to speed up next search */
list_del(&slab->slab_list);
if (!slab->active) {
list_add_tail(&slab->slab_list, &n->slabs_free);
n->free_slabs++;
} else
list_add_tail(&slab->slab_list, &n->slabs_partial);
list_for_each_entry(slab, &n->slabs_partial, slab_list) {
if (!slab_test_pfmemalloc(slab))
return slab;
}
n->free_touched = 1;
list_for_each_entry(slab, &n->slabs_free, slab_list) {
if (!slab_test_pfmemalloc(slab)) {
n->free_slabs--;
return slab;
}
}
return NULL;
}
static struct slab *get_first_slab(struct kmem_cache_node *n, bool pfmemalloc)
{
struct slab *slab;
assert_spin_locked(&n->list_lock);
slab = list_first_entry_or_null(&n->slabs_partial, struct slab,
slab_list);
if (!slab) {
n->free_touched = 1;
slab = list_first_entry_or_null(&n->slabs_free, struct slab,
slab_list);
if (slab)
n->free_slabs--;
}
if (sk_memalloc_socks())
slab = get_valid_first_slab(n, slab, pfmemalloc);
return slab;
}
static noinline void *cache_alloc_pfmemalloc(struct kmem_cache *cachep,
struct kmem_cache_node *n, gfp_t flags)
{
struct slab *slab;
void *obj;
void *list = NULL;
if (!gfp_pfmemalloc_allowed(flags))
return NULL;
spin_lock(&n->list_lock);
slab = get_first_slab(n, true);
if (!slab) {
spin_unlock(&n->list_lock);
return NULL;
}
obj = slab_get_obj(cachep, slab);
n->free_objects--;
fixup_slab_list(cachep, n, slab, &list);
spin_unlock(&n->list_lock);
fixup_objfreelist_debug(cachep, &list);
return obj;
}
/*
* Slab list should be fixed up by fixup_slab_list() for existing slab
* or cache_grow_end() for new slab
*/
static __always_inline int alloc_block(struct kmem_cache *cachep,
struct array_cache *ac, struct slab *slab, int batchcount)
{
/*
* There must be at least one object available for
* allocation.
*/
BUG_ON(slab->active >= cachep->num);
while (slab->active < cachep->num && batchcount--) {
STATS_INC_ALLOCED(cachep);
STATS_INC_ACTIVE(cachep);
STATS_SET_HIGH(cachep);
ac->entry[ac->avail++] = slab_get_obj(cachep, slab);
}
return batchcount;
}
static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags)
{
int batchcount;
struct kmem_cache_node *n;
struct array_cache *ac, *shared;
int node;
void *list = NULL;
struct slab *slab;
check_irq_off();
node = numa_mem_id();
ac = cpu_cache_get(cachep);
batchcount = ac->batchcount;
if (!ac->touched && batchcount > BATCHREFILL_LIMIT) {
/*
* If there was little recent activity on this cache, then
* perform only a partial refill. Otherwise we could generate
* refill bouncing.
*/
batchcount = BATCHREFILL_LIMIT;
}
n = get_node(cachep, node);
BUG_ON(ac->avail > 0 || !n);
shared = READ_ONCE(n->shared);
if (!n->free_objects && (!shared || !shared->avail))
goto direct_grow;
spin_lock(&n->list_lock);
shared = READ_ONCE(n->shared);
/* See if we can refill from the shared array */
if (shared && transfer_objects(ac, shared, batchcount)) {
shared->touched = 1;
goto alloc_done;
}
while (batchcount > 0) {
/* Get slab alloc is to come from. */
slab = get_first_slab(n, false);
if (!slab)
goto must_grow;
check_spinlock_acquired(cachep);
batchcount = alloc_block(cachep, ac, slab, batchcount);
fixup_slab_list(cachep, n, slab, &list);
}
must_grow:
n->free_objects -= ac->avail;
alloc_done:
spin_unlock(&n->list_lock);
fixup_objfreelist_debug(cachep, &list);
direct_grow:
if (unlikely(!ac->avail)) {
/* Check if we can use obj in pfmemalloc slab */
if (sk_memalloc_socks()) {
void *obj = cache_alloc_pfmemalloc(cachep, n, flags);
if (obj)
return obj;
}
slab = cache_grow_begin(cachep, gfp_exact_node(flags), node);
/*
* cache_grow_begin() can reenable interrupts,
* then ac could change.
*/
ac = cpu_cache_get(cachep);
if (!ac->avail && slab)
alloc_block(cachep, ac, slab, batchcount);
cache_grow_end(cachep, slab);
if (!ac->avail)
return NULL;
}
ac->touched = 1;
return ac->entry[--ac->avail];
}
#if DEBUG
static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep,
gfp_t flags, void *objp, unsigned long caller)
{
WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO));
if (!objp || is_kfence_address(objp))
return objp;
if (cachep->flags & SLAB_POISON) {
check_poison_obj(cachep, objp);
slab_kernel_map(cachep, objp, 1);
poison_obj(cachep, objp, POISON_INUSE);
}
if (cachep->flags & SLAB_STORE_USER)
*dbg_userword(cachep, objp) = (void *)caller;
if (cachep->flags & SLAB_RED_ZONE) {
if (*dbg_redzone1(cachep, objp) != RED_INACTIVE ||
*dbg_redzone2(cachep, objp) != RED_INACTIVE) {
slab_error(cachep, "double free, or memory outside object was overwritten");
pr_err("%px: redzone 1:0x%llx, redzone 2:0x%llx\n",
objp, *dbg_redzone1(cachep, objp),
*dbg_redzone2(cachep, objp));
}
*dbg_redzone1(cachep, objp) = RED_ACTIVE;
*dbg_redzone2(cachep, objp) = RED_ACTIVE;
}
objp += obj_offset(cachep);
if (cachep->ctor && cachep->flags & SLAB_POISON)
cachep->ctor(objp);
if ((unsigned long)objp & (arch_slab_minalign() - 1)) {
pr_err("0x%px: not aligned to arch_slab_minalign()=%u\n", objp,
arch_slab_minalign());
}
return objp;
}
#else
#define cache_alloc_debugcheck_after(a, b, objp, d) (objp)
#endif
static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
{
void *objp;
struct array_cache *ac;
check_irq_off();
ac = cpu_cache_get(cachep);
if (likely(ac->avail)) {
ac->touched = 1;
objp = ac->entry[--ac->avail];
STATS_INC_ALLOCHIT(cachep);
goto out;
}
STATS_INC_ALLOCMISS(cachep);
objp = cache_alloc_refill(cachep, flags);
/*
* the 'ac' may be updated by cache_alloc_refill(),
* and kmemleak_erase() requires its correct value.
*/
ac = cpu_cache_get(cachep);
out:
/*
* To avoid a false negative, if an object that is in one of the
* per-CPU caches is leaked, we need to make sure kmemleak doesn't
* treat the array pointers as a reference to the object.
*/
if (objp)
kmemleak_erase(&ac->entry[ac->avail]);
return objp;
}
#ifdef CONFIG_NUMA
static void *____cache_alloc_node(struct kmem_cache *, gfp_t, int);
/*
* Try allocating on another node if PFA_SPREAD_SLAB is a mempolicy is set.
*
* If we are in_interrupt, then process context, including cpusets and
* mempolicy, may not apply and should not be used for allocation policy.
*/
static void *alternate_node_alloc(struct kmem_cache *cachep, gfp_t flags)
{
int nid_alloc, nid_here;
if (in_interrupt() || (flags & __GFP_THISNODE))
return NULL;
nid_alloc = nid_here = numa_mem_id();
if (cpuset_do_slab_mem_spread() && (cachep->flags & SLAB_MEM_SPREAD))
nid_alloc = cpuset_slab_spread_node();
else if (current->mempolicy)
nid_alloc = mempolicy_slab_node();
if (nid_alloc != nid_here)
return ____cache_alloc_node(cachep, flags, nid_alloc);
return NULL;
}
/*
* Fallback function if there was no memory available and no objects on a
* certain node and fall back is permitted. First we scan all the
* available node for available objects. If that fails then we
* perform an allocation without specifying a node. This allows the page
* allocator to do its reclaim / fallback magic. We then insert the
* slab into the proper nodelist and then allocate from it.
*/
static void *fallback_alloc(struct kmem_cache *cache, gfp_t flags)
{
struct zonelist *zonelist;
struct zoneref *z;
struct zone *zone;
enum zone_type highest_zoneidx = gfp_zone(flags);
void *obj = NULL;
struct slab *slab;
int nid;
unsigned int cpuset_mems_cookie;
if (flags & __GFP_THISNODE)
return NULL;
retry_cpuset:
cpuset_mems_cookie = read_mems_allowed_begin();
zonelist = node_zonelist(mempolicy_slab_node(), flags);
retry:
/*
* Look through allowed nodes for objects available
* from existing per node queues.
*/
for_each_zone_zonelist(zone, z, zonelist, highest_zoneidx) {
nid = zone_to_nid(zone);
if (cpuset_zone_allowed(zone, flags) &&
get_node(cache, nid) &&
get_node(cache, nid)->free_objects) {
obj = ____cache_alloc_node(cache,
gfp_exact_node(flags), nid);
if (obj)
break;
}
}
if (!obj) {
/*
* This allocation will be performed within the constraints
* of the current cpuset / memory policy requirements.
* We may trigger various forms of reclaim on the allowed
* set and go into memory reserves if necessary.
*/
slab = cache_grow_begin(cache, flags, numa_mem_id());
cache_grow_end(cache, slab);
if (slab) {
nid = slab_nid(slab);
obj = ____cache_alloc_node(cache,
gfp_exact_node(flags), nid);
/*
* Another processor may allocate the objects in
* the slab since we are not holding any locks.
*/
if (!obj)
goto retry;
}
}
if (unlikely(!obj && read_mems_allowed_retry(cpuset_mems_cookie)))
goto retry_cpuset;
return obj;
}
/*
* An interface to enable slab creation on nodeid
*/
static void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags,
int nodeid)
{
struct slab *slab;
struct kmem_cache_node *n;
void *obj = NULL;
void *list = NULL;
VM_BUG_ON(nodeid < 0 || nodeid >= MAX_NUMNODES);
n = get_node(cachep, nodeid);
BUG_ON(!n);
check_irq_off();
spin_lock(&n->list_lock);
slab = get_first_slab(n, false);
if (!slab)
goto must_grow;
check_spinlock_acquired_node(cachep, nodeid);
STATS_INC_NODEALLOCS(cachep);
STATS_INC_ACTIVE(cachep);
STATS_SET_HIGH(cachep);
BUG_ON(slab->active == cachep->num);
obj = slab_get_obj(cachep, slab);
n->free_objects--;
fixup_slab_list(cachep, n, slab, &list);
spin_unlock(&n->list_lock);
fixup_objfreelist_debug(cachep, &list);
return obj;
must_grow:
spin_unlock(&n->list_lock);
slab = cache_grow_begin(cachep, gfp_exact_node(flags), nodeid);
if (slab) {
/* This slab isn't counted yet so don't update free_objects */
obj = slab_get_obj(cachep, slab);
}
cache_grow_end(cachep, slab);
return obj ? obj : fallback_alloc(cachep, flags);
}
static __always_inline void *
__do_cache_alloc(struct kmem_cache *cachep, gfp_t flags, int nodeid)
{
void *objp = NULL;
int slab_node = numa_mem_id();
if (nodeid == NUMA_NO_NODE) {
if (current->mempolicy || cpuset_do_slab_mem_spread()) {
objp = alternate_node_alloc(cachep, flags);
if (objp)
goto out;
}
/*
* Use the locally cached objects if possible.
* However ____cache_alloc does not allow fallback
* to other nodes. It may fail while we still have
* objects on other nodes available.
*/
objp = ____cache_alloc(cachep, flags);
nodeid = slab_node;
} else if (nodeid == slab_node) {
objp = ____cache_alloc(cachep, flags);
} else if (!get_node(cachep, nodeid)) {
/* Node not bootstrapped yet */
objp = fallback_alloc(cachep, flags);
goto out;
}
/*
* We may just have run out of memory on the local node.
* ____cache_alloc_node() knows how to locate memory on other nodes
*/
if (!objp)
objp = ____cache_alloc_node(cachep, flags, nodeid);
out:
return objp;
}
#else
static __always_inline void *
__do_cache_alloc(struct kmem_cache *cachep, gfp_t flags, int nodeid __maybe_unused)
{
return ____cache_alloc(cachep, flags);
}
#endif /* CONFIG_NUMA */
static __always_inline void *
slab_alloc_node(struct kmem_cache *cachep, struct list_lru *lru, gfp_t flags,
int nodeid, size_t orig_size, unsigned long caller)
{
unsigned long save_flags;
void *objp;
struct obj_cgroup *objcg = NULL;
bool init = false;
flags &= gfp_allowed_mask;
cachep = slab_pre_alloc_hook(cachep, lru, &objcg, 1, flags);
if (unlikely(!cachep))
return NULL;
objp = kfence_alloc(cachep, orig_size, flags);
if (unlikely(objp))
goto out;
local_irq_save(save_flags);
objp = __do_cache_alloc(cachep, flags, nodeid);
local_irq_restore(save_flags);
objp = cache_alloc_debugcheck_after(cachep, flags, objp, caller);
prefetchw(objp);
init = slab_want_init_on_alloc(flags, cachep);
out:
slab_post_alloc_hook(cachep, objcg, flags, 1, &objp, init);
return objp;
}
static __always_inline void *
slab_alloc(struct kmem_cache *cachep, struct list_lru *lru, gfp_t flags,
size_t orig_size, unsigned long caller)
{
return slab_alloc_node(cachep, lru, flags, NUMA_NO_NODE, orig_size,
caller);
}
/*
* Caller needs to acquire correct kmem_cache_node's list_lock
* @list: List of detached free slabs should be freed by caller
*/
static void free_block(struct kmem_cache *cachep, void **objpp,
int nr_objects, int node, struct list_head *list)
{
int i;
struct kmem_cache_node *n = get_node(cachep, node);
struct slab *slab;
n->free_objects += nr_objects;
for (i = 0; i < nr_objects; i++) {
void *objp;
struct slab *slab;
objp = objpp[i];
slab = virt_to_slab(objp);
list_del(&slab->slab_list);
check_spinlock_acquired_node(cachep, node);
slab_put_obj(cachep, slab, objp);
STATS_DEC_ACTIVE(cachep);
/* fixup slab chains */
if (slab->active == 0) {
list_add(&slab->slab_list, &n->slabs_free);
n->free_slabs++;
} else {
/* Unconditionally move a slab to the end of the
* partial list on free - maximum time for the
* other objects to be freed, too.
*/
list_add_tail(&slab->slab_list, &n->slabs_partial);
}
}
while (n->free_objects > n->free_limit && !list_empty(&n->slabs_free)) {
n->free_objects -= cachep->num;
slab = list_last_entry(&n->slabs_free, struct slab, slab_list);
list_move(&slab->slab_list, list);
n->free_slabs--;
n->total_slabs--;
}
}
static void cache_flusharray(struct kmem_cache *cachep, struct array_cache *ac)
{
int batchcount;
struct kmem_cache_node *n;
int node = numa_mem_id();
LIST_HEAD(list);
batchcount = ac->batchcount;
check_irq_off();
n = get_node(cachep, node);
spin_lock(&n->list_lock);
if (n->shared) {
struct array_cache *shared_array = n->shared;
int max = shared_array->limit - shared_array->avail;
if (max) {
if (batchcount > max)
batchcount = max;
memcpy(&(shared_array->entry[shared_array->avail]),
ac->entry, sizeof(void *) * batchcount);
shared_array->avail += batchcount;
goto free_done;
}
}
free_block(cachep, ac->entry, batchcount, node, &list);
free_done:
#if STATS
{
int i = 0;
struct slab *slab;
list_for_each_entry(slab, &n->slabs_free, slab_list) {
BUG_ON(slab->active);
i++;
}
STATS_SET_FREEABLE(cachep, i);
}
#endif
spin_unlock(&n->list_lock);
ac->avail -= batchcount;
memmove(ac->entry, &(ac->entry[batchcount]), sizeof(void *)*ac->avail);
slabs_destroy(cachep, &list);
}
/*
* Release an obj back to its cache. If the obj has a constructed state, it must
* be in this state _before_ it is released. Called with disabled ints.
*/
static __always_inline void __cache_free(struct kmem_cache *cachep, void *objp,
unsigned long caller)
{
bool init;
memcg_slab_free_hook(cachep, virt_to_slab(objp), &objp, 1);
if (is_kfence_address(objp)) {
kmemleak_free_recursive(objp, cachep->flags);
__kfence_free(objp);
return;
}
/*
* As memory initialization might be integrated into KASAN,
* kasan_slab_free and initialization memset must be
* kept together to avoid discrepancies in behavior.
*/
init = slab_want_init_on_free(cachep);
if (init && !kasan_has_integrated_init())
memset(objp, 0, cachep->object_size);
/* KASAN might put objp into memory quarantine, delaying its reuse. */
if (kasan_slab_free(cachep, objp, init))
return;
/* Use KCSAN to help debug racy use-after-free. */
if (!(cachep->flags & SLAB_TYPESAFE_BY_RCU))
__kcsan_check_access(objp, cachep->object_size,
KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ASSERT);
___cache_free(cachep, objp, caller);
}
void ___cache_free(struct kmem_cache *cachep, void *objp,
unsigned long caller)
{
struct array_cache *ac = cpu_cache_get(cachep);
check_irq_off();
kmemleak_free_recursive(objp, cachep->flags);
objp = cache_free_debugcheck(cachep, objp, caller);
/*
* Skip calling cache_free_alien() when the platform is not numa.
* This will avoid cache misses that happen while accessing slabp (which
* is per page memory reference) to get nodeid. Instead use a global
* variable to skip the call, which is mostly likely to be present in
* the cache.
*/
if (nr_online_nodes > 1 && cache_free_alien(cachep, objp))
return;
if (ac->avail < ac->limit) {
STATS_INC_FREEHIT(cachep);
} else {
STATS_INC_FREEMISS(cachep);
cache_flusharray(cachep, ac);
}
if (sk_memalloc_socks()) {
struct slab *slab = virt_to_slab(objp);
if (unlikely(slab_test_pfmemalloc(slab))) {
cache_free_pfmemalloc(cachep, slab, objp);
return;
}
}
__free_one(ac, objp);
}
static __always_inline
void *__kmem_cache_alloc_lru(struct kmem_cache *cachep, struct list_lru *lru,
gfp_t flags)
{
void *ret = slab_alloc(cachep, lru, flags, cachep->object_size, _RET_IP_);
trace_kmem_cache_alloc(_RET_IP_, ret, cachep, flags, NUMA_NO_NODE);
return ret;
}
/**
* kmem_cache_alloc - Allocate an object
* @cachep: The cache to allocate from.
* @flags: See kmalloc().
*
* Allocate an object from this cache. The flags are only relevant
* if the cache has no available objects.
*
* Return: pointer to the new object or %NULL in case of error
*/
void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
{
return __kmem_cache_alloc_lru(cachep, NULL, flags);
}
EXPORT_SYMBOL(kmem_cache_alloc);
void *kmem_cache_alloc_lru(struct kmem_cache *cachep, struct list_lru *lru,
gfp_t flags)
{
return __kmem_cache_alloc_lru(cachep, lru, flags);
}
EXPORT_SYMBOL(kmem_cache_alloc_lru);
static __always_inline void
cache_alloc_debugcheck_after_bulk(struct kmem_cache *s, gfp_t flags,
size_t size, void **p, unsigned long caller)
{
size_t i;
for (i = 0; i < size; i++)
p[i] = cache_alloc_debugcheck_after(s, flags, p[i], caller);
}
int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
void **p)
{
size_t i;
struct obj_cgroup *objcg = NULL;
s = slab_pre_alloc_hook(s, NULL, &objcg, size, flags);
if (!s)
return 0;
local_irq_disable();
for (i = 0; i < size; i++) {
void *objp = kfence_alloc(s, s->object_size, flags) ?:
__do_cache_alloc(s, flags, NUMA_NO_NODE);
if (unlikely(!objp))
goto error;
p[i] = objp;
}
local_irq_enable();
cache_alloc_debugcheck_after_bulk(s, flags, size, p, _RET_IP_);
/*
* memcg and kmem_cache debug support and memory initialization.
* Done outside of the IRQ disabled section.
*/
slab_post_alloc_hook(s, objcg, flags, size, p,
slab_want_init_on_alloc(flags, s));
/* FIXME: Trace call missing. Christoph would like a bulk variant */
return size;
error:
local_irq_enable();
cache_alloc_debugcheck_after_bulk(s, flags, i, p, _RET_IP_);
slab_post_alloc_hook(s, objcg, flags, i, p, false);
kmem_cache_free_bulk(s, i, p);
return 0;
}
EXPORT_SYMBOL(kmem_cache_alloc_bulk);
/**
* kmem_cache_alloc_node - Allocate an object on the specified node
* @cachep: The cache to allocate from.
* @flags: See kmalloc().
* @nodeid: node number of the target node.
*
* Identical to kmem_cache_alloc 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 *cachep, gfp_t flags, int nodeid)
{
void *ret = slab_alloc_node(cachep, NULL, flags, nodeid, cachep->object_size, _RET_IP_);
trace_kmem_cache_alloc(_RET_IP_, ret, cachep, flags, nodeid);
return ret;
}
EXPORT_SYMBOL(kmem_cache_alloc_node);
void *__kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t flags,
int nodeid, size_t orig_size,
unsigned long caller)
{
return slab_alloc_node(cachep, NULL, flags, nodeid,
orig_size, caller);
}
#ifdef CONFIG_PRINTK
void __kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab)
{
struct kmem_cache *cachep;
unsigned int objnr;
void *objp;
kpp->kp_ptr = object;
kpp->kp_slab = slab;
cachep = slab->slab_cache;
kpp->kp_slab_cache = cachep;
objp = object - obj_offset(cachep);
kpp->kp_data_offset = obj_offset(cachep);
slab = virt_to_slab(objp);
objnr = obj_to_index(cachep, slab, objp);
objp = index_to_obj(cachep, slab, objnr);
kpp->kp_objp = objp;
if (DEBUG && cachep->flags & SLAB_STORE_USER)
kpp->kp_ret = *dbg_userword(cachep, objp);
}
#endif
static __always_inline
void __do_kmem_cache_free(struct kmem_cache *cachep, void *objp,
unsigned long caller)
{
unsigned long flags;
local_irq_save(flags);
debug_check_no_locks_freed(objp, cachep->object_size);
if (!(cachep->flags & SLAB_DEBUG_OBJECTS))
debug_check_no_obj_freed(objp, cachep->object_size);
__cache_free(cachep, objp, caller);
local_irq_restore(flags);
}
void __kmem_cache_free(struct kmem_cache *cachep, void *objp,
unsigned long caller)
{
__do_kmem_cache_free(cachep, objp, caller);
}
/**
* kmem_cache_free - Deallocate an object
* @cachep: The cache the allocation was from.
* @objp: The previously allocated object.
*
* Free an object which was previously allocated from this
* cache.
*/
void kmem_cache_free(struct kmem_cache *cachep, void *objp)
{
cachep = cache_from_obj(cachep, objp);
if (!cachep)
return;
trace_kmem_cache_free(_RET_IP_, objp, cachep);
__do_kmem_cache_free(cachep, objp, _RET_IP_);
}
EXPORT_SYMBOL(kmem_cache_free);
void kmem_cache_free_bulk(struct kmem_cache *orig_s, size_t size, void **p)
{
local_irq_disable();
for (int i = 0; i < size; i++) {
void *objp = p[i];
struct kmem_cache *s;
if (!orig_s) {
struct folio *folio = virt_to_folio(objp);
/* called via kfree_bulk */
if (!folio_test_slab(folio)) {
local_irq_enable();
free_large_kmalloc(folio, objp);
local_irq_disable();
continue;
}
s = folio_slab(folio)->slab_cache;
} else {
s = cache_from_obj(orig_s, objp);
}
if (!s)
continue;
debug_check_no_locks_freed(objp, s->object_size);
if (!(s->flags & SLAB_DEBUG_OBJECTS))
debug_check_no_obj_freed(objp, s->object_size);
__cache_free(s, objp, _RET_IP_);
}
local_irq_enable();
/* FIXME: add tracing */
}
EXPORT_SYMBOL(kmem_cache_free_bulk);
/*
* This initializes kmem_cache_node or resizes various caches for all nodes.
*/
static int setup_kmem_cache_nodes(struct kmem_cache *cachep, gfp_t gfp)
{
int ret;
int node;
struct kmem_cache_node *n;
for_each_online_node(node) {
ret = setup_kmem_cache_node(cachep, node, gfp, true);
if (ret)
goto fail;
}
return 0;
fail:
if (!cachep->list.next) {
/* Cache is not active yet. Roll back what we did */
node--;
while (node >= 0) {
n = get_node(cachep, node);
if (n) {
kfree(n->shared);
free_alien_cache(n->alien);
kfree(n);
cachep->node[node] = NULL;
}
node--;
}
}
return -ENOMEM;
}
/* Always called with the slab_mutex held */
static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
int batchcount, int shared, gfp_t gfp)
{
struct array_cache __percpu *cpu_cache, *prev;
int cpu;
cpu_cache = alloc_kmem_cache_cpus(cachep, limit, batchcount);
if (!cpu_cache)
return -ENOMEM;
prev = cachep->cpu_cache;
cachep->cpu_cache = cpu_cache;
/*
* Without a previous cpu_cache there's no need to synchronize remote
* cpus, so skip the IPIs.
*/
if (prev)
kick_all_cpus_sync();
check_irq_on();
cachep->batchcount = batchcount;
cachep->limit = limit;
cachep->shared = shared;
if (!prev)
goto setup_node;
for_each_online_cpu(cpu) {
LIST_HEAD(list);
int node;
struct kmem_cache_node *n;
struct array_cache *ac = per_cpu_ptr(prev, cpu);
node = cpu_to_mem(cpu);
n = get_node(cachep, node);
spin_lock_irq(&n->list_lock);
free_block(cachep, ac->entry, ac->avail, node, &list);
spin_unlock_irq(&n->list_lock);
slabs_destroy(cachep, &list);
}
free_percpu(prev);
setup_node:
return setup_kmem_cache_nodes(cachep, gfp);
}
/* Called with slab_mutex held always */
static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp)
{
int err;
int limit = 0;
int shared = 0;
int batchcount = 0;
err = cache_random_seq_create(cachep, cachep->num, gfp);
if (err)
goto end;
/*
* The head array serves three purposes:
* - create a LIFO ordering, i.e. return objects that are cache-warm
* - reduce the number of spinlock operations.
* - reduce the number of linked list operations on the slab and
* bufctl chains: array operations are cheaper.
* The numbers are guessed, we should auto-tune as described by
* Bonwick.
*/
if (cachep->size > 131072)
limit = 1;
else if (cachep->size > PAGE_SIZE)
limit = 8;
else if (cachep->size > 1024)
limit = 24;
else if (cachep->size > 256)
limit = 54;
else
limit = 120;
/*
* CPU bound tasks (e.g. network routing) can exhibit cpu bound
* allocation behaviour: Most allocs on one cpu, most free operations
* on another cpu. For these cases, an efficient object passing between
* cpus is necessary. This is provided by a shared array. The array
* replaces Bonwick's magazine layer.
* On uniprocessor, it's functionally equivalent (but less efficient)
* to a larger limit. Thus disabled by default.
*/
shared = 0;
if (cachep->size <= PAGE_SIZE && num_possible_cpus() > 1)
shared = 8;
#if DEBUG
/*
* With debugging enabled, large batchcount lead to excessively long
* periods with disabled local interrupts. Limit the batchcount
*/
if (limit > 32)
limit = 32;
#endif
batchcount = (limit + 1) / 2;
err = do_tune_cpucache(cachep, limit, batchcount, shared, gfp);
end:
if (err)
pr_err("enable_cpucache failed for %s, error %d\n",
cachep->name, -err);
return err;
}
/*
* Drain an array if it contains any elements taking the node lock only if
* necessary. Note that the node listlock also protects the array_cache
* if drain_array() is used on the shared array.
*/
static void drain_array(struct kmem_cache *cachep, struct kmem_cache_node *n,
struct array_cache *ac, int node)
{
LIST_HEAD(list);
/* ac from n->shared can be freed if we don't hold the slab_mutex. */
check_mutex_acquired();
if (!ac || !ac->avail)
return;
if (ac->touched) {
ac->touched = 0;
return;
}
spin_lock_irq(&n->list_lock);
drain_array_locked(cachep, ac, node, false, &list);
spin_unlock_irq(&n->list_lock);
slabs_destroy(cachep, &list);
}
/**
* cache_reap - Reclaim memory from caches.
* @w: work descriptor
*
* Called from workqueue/eventd every few seconds.
* Purpose:
* - clear the per-cpu caches for this CPU.
* - return freeable pages to the main free memory pool.
*
* If we cannot acquire the cache chain mutex then just give up - we'll try
* again on the next iteration.
*/
static void cache_reap(struct work_struct *w)
{
struct kmem_cache *searchp;
struct kmem_cache_node *n;
int node = numa_mem_id();
struct delayed_work *work = to_delayed_work(w);
if (!mutex_trylock(&slab_mutex))
/* Give up. Setup the next iteration. */
goto out;
list_for_each_entry(searchp, &slab_caches, list) {
check_irq_on();
/*
* We only take the node lock if absolutely necessary and we
* have established with reasonable certainty that
* we can do some work if the lock was obtained.
*/
n = get_node(searchp, node);
reap_alien(searchp, n);
drain_array(searchp, n, cpu_cache_get(searchp), node);
/*
* These are racy checks but it does not matter
* if we skip one check or scan twice.
*/
if (time_after(n->next_reap, jiffies))
goto next;
n->next_reap = jiffies + REAPTIMEOUT_NODE;
drain_array(searchp, n, n->shared, node);
if (n->free_touched)
n->free_touched = 0;
else {
int freed;
freed = drain_freelist(searchp, n, (n->free_limit +
5 * searchp->num - 1) / (5 * searchp->num));
STATS_ADD_REAPED(searchp, freed);
}
next:
cond_resched();
}
check_irq_on();
mutex_unlock(&slab_mutex);
next_reap_node();
out:
/* Set up the next iteration */
schedule_delayed_work_on(smp_processor_id(), work,
round_jiffies_relative(REAPTIMEOUT_AC));
}
void get_slabinfo(struct kmem_cache *cachep, struct slabinfo *sinfo)
{
unsigned long active_objs, num_objs, active_slabs;
unsigned long total_slabs = 0, free_objs = 0, shared_avail = 0;
unsigned long free_slabs = 0;
int node;
struct kmem_cache_node *n;
for_each_kmem_cache_node(cachep, node, n) {
check_irq_on();
spin_lock_irq(&n->list_lock);
total_slabs += n->total_slabs;
free_slabs += n->free_slabs;
free_objs += n->free_objects;
if (n->shared)
shared_avail += n->shared->avail;
spin_unlock_irq(&n->list_lock);
}
num_objs = total_slabs * cachep->num;
active_slabs = total_slabs - free_slabs;
active_objs = num_objs - free_objs;
sinfo->active_objs = active_objs;
sinfo->num_objs = num_objs;
sinfo->active_slabs = active_slabs;
sinfo->num_slabs = total_slabs;
sinfo->shared_avail = shared_avail;
sinfo->limit = cachep->limit;
sinfo->batchcount = cachep->batchcount;
sinfo->shared = cachep->shared;
sinfo->objects_per_slab = cachep->num;
sinfo->cache_order = cachep->gfporder;
}
void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *cachep)
{
#if STATS
{ /* node stats */
unsigned long high = cachep->high_mark;
unsigned long allocs = cachep->num_allocations;
unsigned long grown = cachep->grown;
unsigned long reaped = cachep->reaped;
unsigned long errors = cachep->errors;
unsigned long max_freeable = cachep->max_freeable;
unsigned long node_allocs = cachep->node_allocs;
unsigned long node_frees = cachep->node_frees;
unsigned long overflows = cachep->node_overflow;
seq_printf(m, " : globalstat %7lu %6lu %5lu %4lu %4lu %4lu %4lu %4lu %4lu",
allocs, high, grown,
reaped, errors, max_freeable, node_allocs,
node_frees, overflows);
}
/* cpu stats */
{
unsigned long allochit = atomic_read(&cachep->allochit);
unsigned long allocmiss = atomic_read(&cachep->allocmiss);
unsigned long freehit = atomic_read(&cachep->freehit);
unsigned long freemiss = atomic_read(&cachep->freemiss);
seq_printf(m, " : cpustat %6lu %6lu %6lu %6lu",
allochit, allocmiss, freehit, freemiss);
}
#endif
}
#define MAX_SLABINFO_WRITE 128
/**
* slabinfo_write - Tuning for the slab allocator
* @file: unused
* @buffer: user buffer
* @count: data length
* @ppos: unused
*
* Return: %0 on success, negative error code otherwise.
*/
ssize_t slabinfo_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos)
{
char kbuf[MAX_SLABINFO_WRITE + 1], *tmp;
int limit, batchcount, shared, res;
struct kmem_cache *cachep;
if (count > MAX_SLABINFO_WRITE)
return -EINVAL;
if (copy_from_user(&kbuf, buffer, count))
return -EFAULT;
kbuf[MAX_SLABINFO_WRITE] = '\0';
tmp = strchr(kbuf, ' ');
if (!tmp)
return -EINVAL;
*tmp = '\0';
tmp++;
if (sscanf(tmp, " %d %d %d", &limit, &batchcount, &shared) != 3)
return -EINVAL;
/* Find the cache in the chain of caches. */
mutex_lock(&slab_mutex);
res = -EINVAL;
list_for_each_entry(cachep, &slab_caches, list) {
if (!strcmp(cachep->name, kbuf)) {
if (limit < 1 || batchcount < 1 ||
batchcount > limit || shared < 0) {
res = 0;
} else {
res = do_tune_cpucache(cachep, limit,
batchcount, shared,
GFP_KERNEL);
}
break;
}
}
mutex_unlock(&slab_mutex);
if (res >= 0)
res = count;
return res;
}
#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 *cachep;
unsigned int objnr;
unsigned long offset;
ptr = kasan_reset_tag(ptr);
/* Find and validate object. */
cachep = slab->slab_cache;
objnr = obj_to_index(cachep, slab, (void *)ptr);
BUG_ON(objnr >= cachep->num);
/* Find offset within object. */
if (is_kfence_address(ptr))
offset = ptr - kfence_object_start(ptr);
else
offset = ptr - index_to_obj(cachep, slab, objnr) - obj_offset(cachep);
/* Allow address range falling entirely within usercopy region. */
if (offset >= cachep->useroffset &&
offset - cachep->useroffset <= cachep->usersize &&
n <= cachep->useroffset - offset + cachep->usersize)
return;
usercopy_abort("SLAB object", cachep->name, to_user, offset, n);
}
#endif /* CONFIG_HARDENED_USERCOPY */
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