// SPDX-License-Identifier: GPL-2.0
/*
* Slab allocator functions that are independent of the allocator strategy
*
* (C) 2012 Christoph Lameter <cl@linux.com>
*/
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/poison.h>
#include <linux/interrupt.h>
#include <linux/memory.h>
#include <linux/cache.h>
#include <linux/compiler.h>
#include <linux/kfence.h>
#include <linux/module.h>
#include <linux/cpu.h>
#include <linux/uaccess.h>
#include <linux/seq_file.h>
#include <linux/dma-mapping.h>
#include <linux/swiotlb.h>
#include <linux/proc_fs.h>
#include <linux/debugfs.h>
#include <linux/kmemleak.h>
#include <linux/kasan.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/page.h>
#include <linux/memcontrol.h>
#include <linux/stackdepot.h>
#include <trace/events/rcu.h>
#include "../kernel/rcu/rcu.h"
#include "internal.h"
#include "slab.h"
#define CREATE_TRACE_POINTS
#include <trace/events/kmem.h>
enum slab_state slab_state;
LIST_HEAD(slab_caches);
DEFINE_MUTEX(slab_mutex);
struct kmem_cache *kmem_cache;
/*
* Set of flags that will prevent slab merging
*/
#define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \
SLAB_FAILSLAB | SLAB_NO_MERGE)
#define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
SLAB_CACHE_DMA32 | SLAB_ACCOUNT)
/*
* Merge control. If this is set then no merging of slab caches will occur.
*/
static bool slab_nomerge = !IS_ENABLED(CONFIG_SLAB_MERGE_DEFAULT);
static int __init setup_slab_nomerge(char *str)
{
slab_nomerge = true;
return 1;
}
static int __init setup_slab_merge(char *str)
{
slab_nomerge = false;
return 1;
}
__setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0);
__setup_param("slub_merge", slub_merge, setup_slab_merge, 0);
__setup("slab_nomerge", setup_slab_nomerge);
__setup("slab_merge", setup_slab_merge);
/*
* Determine the size of a slab object
*/
unsigned int kmem_cache_size(struct kmem_cache *s)
{
return s->object_size;
}
EXPORT_SYMBOL(kmem_cache_size);
#ifdef CONFIG_DEBUG_VM
static bool kmem_cache_is_duplicate_name(const char *name)
{
struct kmem_cache *s;
list_for_each_entry(s, &slab_caches, list) {
if (!strcmp(s->name, name))
return true;
}
return false;
}
static int kmem_cache_sanity_check(const char *name, unsigned int size)
{
if (!name || in_interrupt() || size > KMALLOC_MAX_SIZE) {
pr_err("kmem_cache_create(%s) integrity check failed\n", name);
return -EINVAL;
}
/* Duplicate names will confuse slabtop, et al */
WARN(kmem_cache_is_duplicate_name(name),
"kmem_cache of name '%s' already exists\n", name);
WARN_ON(strchr(name, ' ')); /* It confuses parsers */
return 0;
}
#else
static inline int kmem_cache_sanity_check(const char *name, unsigned int size)
{
return 0;
}
#endif
/*
* Figure out what the alignment of the objects will be given a set of
* flags, a user specified alignment and the size of the objects.
*/
static unsigned int calculate_alignment(slab_flags_t flags,
unsigned int align, unsigned int size)
{
/*
* If the user wants hardware cache aligned objects then follow that
* suggestion if the object is sufficiently large.
*
* The hardware cache alignment cannot override the specified
* alignment though. If that is greater then use it.
*/
if (flags & SLAB_HWCACHE_ALIGN) {
unsigned int ralign;
ralign = cache_line_size();
while (size <= ralign / 2)
ralign /= 2;
align = max(align, ralign);
}
align = max(align, arch_slab_minalign());
return ALIGN(align, sizeof(void *));
}
/*
* Find a mergeable slab cache
*/
int slab_unmergeable(struct kmem_cache *s)
{
if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE))
return 1;
if (s->ctor)
return 1;
#ifdef CONFIG_HARDENED_USERCOPY
if (s->usersize)
return 1;
#endif
/*
* We may have set a slab to be unmergeable during bootstrap.
*/
if (s->refcount < 0)
return 1;
return 0;
}
struct kmem_cache *find_mergeable(unsigned int size, unsigned int align,
slab_flags_t flags, const char *name, void (*ctor)(void *))
{
struct kmem_cache *s;
if (slab_nomerge)
return NULL;
if (ctor)
return NULL;
flags = kmem_cache_flags(flags, name);
if (flags & SLAB_NEVER_MERGE)
return NULL;
size = ALIGN(size, sizeof(void *));
align = calculate_alignment(flags, align, size);
size = ALIGN(size, align);
list_for_each_entry_reverse(s, &slab_caches, list) {
if (slab_unmergeable(s))
continue;
if (size > s->size)
continue;
if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME))
continue;
/*
* Check if alignment is compatible.
* Courtesy of Adrian Drzewiecki
*/
if ((s->size & ~(align - 1)) != s->size)
continue;
if (s->size - size >= sizeof(void *))
continue;
return s;
}
return NULL;
}
static struct kmem_cache *create_cache(const char *name,
unsigned int object_size,
struct kmem_cache_args *args,
slab_flags_t flags)
{
struct kmem_cache *s;
int err;
/* If a custom freelist pointer is requested make sure it's sane. */
err = -EINVAL;
if (args->use_freeptr_offset &&
(args->freeptr_offset >= object_size ||
!(flags & SLAB_TYPESAFE_BY_RCU) ||
!IS_ALIGNED(args->freeptr_offset, __alignof__(freeptr_t))))
goto out;
err = -ENOMEM;
s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
if (!s)
goto out;
err = do_kmem_cache_create(s, name, object_size, args, flags);
if (err)
goto out_free_cache;
s->refcount = 1;
list_add(&s->list, &slab_caches);
return s;
out_free_cache:
kmem_cache_free(kmem_cache, s);
out:
return ERR_PTR(err);
}
/**
* __kmem_cache_create_args - Create a kmem cache.
* @name: A string which is used in /proc/slabinfo to identify this cache.
* @object_size: The size of objects to be created in this cache.
* @args: Additional arguments for the cache creation (see
* &struct kmem_cache_args).
* @flags: See the desriptions of individual flags. The common ones are listed
* in the description below.
*
* Not to be called directly, use the kmem_cache_create() wrapper with the same
* parameters.
*
* Commonly used @flags:
*
* &SLAB_ACCOUNT - Account allocations to memcg.
*
* &SLAB_HWCACHE_ALIGN - Align objects on cache line boundaries.
*
* &SLAB_RECLAIM_ACCOUNT - Objects are reclaimable.
*
* &SLAB_TYPESAFE_BY_RCU - Slab page (not individual objects) freeing delayed
* by a grace period - see the full description before using.
*
* Context: Cannot be called within a interrupt, but can be interrupted.
*
* Return: a pointer to the cache on success, NULL on failure.
*/
struct kmem_cache *__kmem_cache_create_args(const char *name,
unsigned int object_size,
struct kmem_cache_args *args,
slab_flags_t flags)
{
struct kmem_cache *s = NULL;
const char *cache_name;
int err;
#ifdef CONFIG_SLUB_DEBUG
/*
* If no slab_debug was enabled globally, the static key is not yet
* enabled by setup_slub_debug(). Enable it if the cache is being
* created with any of the debugging flags passed explicitly.
* It's also possible that this is the first cache created with
* SLAB_STORE_USER and we should init stack_depot for it.
*/
if (flags & SLAB_DEBUG_FLAGS)
static_branch_enable(&slub_debug_enabled);
if (flags & SLAB_STORE_USER)
stack_depot_init();
#endif
mutex_lock(&slab_mutex);
err = kmem_cache_sanity_check(name, object_size);
if (err) {
goto out_unlock;
}
/* Refuse requests with allocator specific flags */
if (flags & ~SLAB_FLAGS_PERMITTED) {
err = -EINVAL;
goto out_unlock;
}
/*
* Some allocators will constraint the set of valid flags to a subset
* of all flags. We expect them to define CACHE_CREATE_MASK in this
* case, and we'll just provide them with a sanitized version of the
* passed flags.
*/
flags &= CACHE_CREATE_MASK;
/* Fail closed on bad usersize of useroffset values. */
if (!IS_ENABLED(CONFIG_HARDENED_USERCOPY) ||
WARN_ON(!args->usersize && args->useroffset) ||
WARN_ON(object_size < args->usersize ||
object_size - args->usersize < args->useroffset))
args->usersize = args->useroffset = 0;
if (!args->usersize)
s = __kmem_cache_alias(name, object_size, args->align, flags,
args->ctor);
if (s)
goto out_unlock;
cache_name = kstrdup_const(name, GFP_KERNEL);
if (!cache_name) {
err = -ENOMEM;
goto out_unlock;
}
args->align = calculate_alignment(flags, args->align, object_size);
s = create_cache(cache_name, object_size, args, flags);
if (IS_ERR(s)) {
err = PTR_ERR(s);
kfree_const(cache_name);
}
out_unlock:
mutex_unlock(&slab_mutex);
if (err) {
if (flags & SLAB_PANIC)
panic("%s: Failed to create slab '%s'. Error %d\n",
__func__, name, err);
else {
pr_warn("%s(%s) failed with error %d\n",
__func__, name, err);
dump_stack();
}
return NULL;
}
return s;
}
EXPORT_SYMBOL(__kmem_cache_create_args);
static struct kmem_cache *kmem_buckets_cache __ro_after_init;
/**
* kmem_buckets_create - Create a set of caches that handle dynamic sized
* allocations via kmem_buckets_alloc()
* @name: A prefix string which is used in /proc/slabinfo to identify this
* cache. The individual caches with have their sizes as the suffix.
* @flags: SLAB flags (see kmem_cache_create() for details).
* @useroffset: Starting offset within an allocation that may be copied
* to/from userspace.
* @usersize: How many bytes, starting at @useroffset, may be copied
* to/from userspace.
* @ctor: A constructor for the objects, run when new allocations are made.
*
* Cannot be called within an interrupt, but can be interrupted.
*
* Return: a pointer to the cache on success, NULL on failure. When
* CONFIG_SLAB_BUCKETS is not enabled, ZERO_SIZE_PTR is returned, and
* subsequent calls to kmem_buckets_alloc() will fall back to kmalloc().
* (i.e. callers only need to check for NULL on failure.)
*/
kmem_buckets *kmem_buckets_create(const char *name, slab_flags_t flags,
unsigned int useroffset,
unsigned int usersize,
void (*ctor)(void *))
{
unsigned long mask = 0;
unsigned int idx;
kmem_buckets *b;
BUILD_BUG_ON(ARRAY_SIZE(kmalloc_caches[KMALLOC_NORMAL]) > BITS_PER_LONG);
/*
* When the separate buckets API is not built in, just return
* a non-NULL value for the kmem_buckets pointer, which will be
* unused when performing allocations.
*/
if (!IS_ENABLED(CONFIG_SLAB_BUCKETS))
return ZERO_SIZE_PTR;
if (WARN_ON(!kmem_buckets_cache))
return NULL;
b = kmem_cache_alloc(kmem_buckets_cache, GFP_KERNEL|__GFP_ZERO);
if (WARN_ON(!b))
return NULL;
flags |= SLAB_NO_MERGE;
for (idx = 0; idx < ARRAY_SIZE(kmalloc_caches[KMALLOC_NORMAL]); idx++) {
char *short_size, *cache_name;
unsigned int cache_useroffset, cache_usersize;
unsigned int size, aligned_idx;
if (!kmalloc_caches[KMALLOC_NORMAL][idx])
continue;
size = kmalloc_caches[KMALLOC_NORMAL][idx]->object_size;
if (!size)
continue;
short_size = strchr(kmalloc_caches[KMALLOC_NORMAL][idx]->name, '-');
if (WARN_ON(!short_size))
goto fail;
if (useroffset >= size) {
cache_useroffset = 0;
cache_usersize = 0;
} else {
cache_useroffset = useroffset;
cache_usersize = min(size - cache_useroffset, usersize);
}
aligned_idx = __kmalloc_index(size, false);
if (!(*b)[aligned_idx]) {
cache_name = kasprintf(GFP_KERNEL, "%s-%s", name, short_size + 1);
if (WARN_ON(!cache_name))
goto fail;
(*b)[aligned_idx] = kmem_cache_create_usercopy(cache_name, size,
0, flags, cache_useroffset,
cache_usersize, ctor);
kfree(cache_name);
if (WARN_ON(!(*b)[aligned_idx]))
goto fail;
set_bit(aligned_idx, &mask);
}
if (idx != aligned_idx)
(*b)[idx] = (*b)[aligned_idx];
}
return b;
fail:
for_each_set_bit(idx, &mask, ARRAY_SIZE(kmalloc_caches[KMALLOC_NORMAL]))
kmem_cache_destroy((*b)[idx]);
kmem_cache_free(kmem_buckets_cache, b);
return NULL;
}
EXPORT_SYMBOL(kmem_buckets_create);
/*
* For a given kmem_cache, kmem_cache_destroy() should only be called
* once or there will be a use-after-free problem. The actual deletion
* and release of the kobject does not need slab_mutex or cpu_hotplug_lock
* protection. So they are now done without holding those locks.
*/
static void kmem_cache_release(struct kmem_cache *s)
{
kfence_shutdown_cache(s);
if (__is_defined(SLAB_SUPPORTS_SYSFS) && slab_state >= FULL)
sysfs_slab_release(s);
else
slab_kmem_cache_release(s);
}
void slab_kmem_cache_release(struct kmem_cache *s)
{
__kmem_cache_release(s);
kfree_const(s->name);
kmem_cache_free(kmem_cache, s);
}
void kmem_cache_destroy(struct kmem_cache *s)
{
int err;
if (unlikely(!s) || !kasan_check_byte(s))
return;
/* in-flight kfree_rcu()'s may include objects from our cache */
kvfree_rcu_barrier();
if (IS_ENABLED(CONFIG_SLUB_RCU_DEBUG) &&
(s->flags & SLAB_TYPESAFE_BY_RCU)) {
/*
* Under CONFIG_SLUB_RCU_DEBUG, when objects in a
* SLAB_TYPESAFE_BY_RCU slab are freed, SLUB will internally
* defer their freeing with call_rcu().
* Wait for such call_rcu() invocations here before actually
* destroying the cache.
*
* It doesn't matter that we haven't looked at the slab refcount
* yet - slabs with SLAB_TYPESAFE_BY_RCU can't be merged, so
* the refcount should be 1 here.
*/
rcu_barrier();
}
cpus_read_lock();
mutex_lock(&slab_mutex);
s->refcount--;
if (s->refcount) {
mutex_unlock(&slab_mutex);
cpus_read_unlock();
return;
}
/* free asan quarantined objects */
kasan_cache_shutdown(s);
err = __kmem_cache_shutdown(s);
if (!slab_in_kunit_test())
WARN(err, "%s %s: Slab cache still has objects when called from %pS",
__func__, s->name, (void *)_RET_IP_);
list_del(&s->list);
mutex_unlock(&slab_mutex);
cpus_read_unlock();
if (slab_state >= FULL)
sysfs_slab_unlink(s);
debugfs_slab_release(s);
if (err)
return;
if (s->flags & SLAB_TYPESAFE_BY_RCU)
rcu_barrier();
kmem_cache_release(s);
}
EXPORT_SYMBOL(kmem_cache_destroy);
/**
* kmem_cache_shrink - Shrink a cache.
* @cachep: The cache to shrink.
*
* Releases as many slabs as possible for a cache.
* To help debugging, a zero exit status indicates all slabs were released.
*
* Return: %0 if all slabs were released, non-zero otherwise
*/
int kmem_cache_shrink(struct kmem_cache *cachep)
{
kasan_cache_shrink(cachep);
return __kmem_cache_shrink(cachep);
}
EXPORT_SYMBOL(kmem_cache_shrink);
bool slab_is_available(void)
{
return slab_state >= UP;
}
#ifdef CONFIG_PRINTK
static void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab)
{
if (__kfence_obj_info(kpp, object, slab))
return;
__kmem_obj_info(kpp, object, slab);
}
/**
* kmem_dump_obj - Print available slab provenance information
* @object: slab object for which to find provenance information.
*
* This function uses pr_cont(), so that the caller is expected to have
* printed out whatever preamble is appropriate. The provenance information
* depends on the type of object and on how much debugging is enabled.
* For a slab-cache object, the fact that it is a slab object is printed,
* and, if available, the slab name, return address, and stack trace from
* the allocation and last free path of that object.
*
* Return: %true if the pointer is to a not-yet-freed object from
* kmalloc() or kmem_cache_alloc(), either %true or %false if the pointer
* is to an already-freed object, and %false otherwise.
*/
bool kmem_dump_obj(void *object)
{
char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc";
int i;
struct slab *slab;
unsigned long ptroffset;
struct kmem_obj_info kp = { };
/* Some arches consider ZERO_SIZE_PTR to be a valid address. */
if (object < (void *)PAGE_SIZE || !virt_addr_valid(object))
return false;
slab = virt_to_slab(object);
if (!slab)
return false;
kmem_obj_info(&kp, object, slab);
if (kp.kp_slab_cache)
pr_cont(" slab%s %s", cp, kp.kp_slab_cache->name);
else
pr_cont(" slab%s", cp);
if (is_kfence_address(object))
pr_cont(" (kfence)");
if (kp.kp_objp)
pr_cont(" start %px", kp.kp_objp);
if (kp.kp_data_offset)
pr_cont(" data offset %lu", kp.kp_data_offset);
if (kp.kp_objp) {
ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset;
pr_cont(" pointer offset %lu", ptroffset);
}
if (kp.kp_slab_cache && kp.kp_slab_cache->object_size)
pr_cont(" size %u", kp.kp_slab_cache->object_size);
if (kp.kp_ret)
pr_cont(" allocated at %pS\n", kp.kp_ret);
else
pr_cont("\n");
for (i = 0; i < ARRAY_SIZE(kp.kp_stack); i++) {
if (!kp.kp_stack[i])
break;
pr_info(" %pS\n", kp.kp_stack[i]);
}
if (kp.kp_free_stack[0])
pr_cont(" Free path:\n");
for (i = 0; i < ARRAY_SIZE(kp.kp_free_stack); i++) {
if (!kp.kp_free_stack[i])
break;
pr_info(" %pS\n", kp.kp_free_stack[i]);
}
return true;
}
EXPORT_SYMBOL_GPL(kmem_dump_obj);
#endif
/* Create a cache during boot when no slab services are available yet */
void __init create_boot_cache(struct kmem_cache *s, const char *name,
unsigned int size, slab_flags_t flags,
unsigned int useroffset, unsigned int usersize)
{
int err;
unsigned int align = ARCH_KMALLOC_MINALIGN;
struct kmem_cache_args kmem_args = {};
/*
* kmalloc caches guarantee alignment of at least the largest
* power-of-two divisor of the size. For power-of-two sizes,
* it is the size itself.
*/
if (flags & SLAB_KMALLOC)
align = max(align, 1U << (ffs(size) - 1));
kmem_args.align = calculate_alignment(flags, align, size);
#ifdef CONFIG_HARDENED_USERCOPY
kmem_args.useroffset = useroffset;
kmem_args.usersize = usersize;
#endif
err = do_kmem_cache_create(s, name, size, &kmem_args, flags);
if (err)
panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n",
name, size, err);
s->refcount = -1; /* Exempt from merging for now */
}
static struct kmem_cache *__init create_kmalloc_cache(const char *name,
unsigned int size,
slab_flags_t flags)
{
struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
if (!s)
panic("Out of memory when creating slab %s\n", name);
create_boot_cache(s, name, size, flags | SLAB_KMALLOC, 0, size);
list_add(&s->list, &slab_caches);
s->refcount = 1;
return s;
}
kmem_buckets kmalloc_caches[NR_KMALLOC_TYPES] __ro_after_init =
{ /* initialization for https://llvm.org/pr42570 */ };
EXPORT_SYMBOL(kmalloc_caches);
#ifdef CONFIG_RANDOM_KMALLOC_CACHES
unsigned long random_kmalloc_seed __ro_after_init;
EXPORT_SYMBOL(random_kmalloc_seed);
#endif
/*
* Conversion table for small slabs sizes / 8 to the index in the
* kmalloc array. This is necessary for slabs < 192 since we have non power
* of two cache sizes there. The size of larger slabs can be determined using
* fls.
*/
u8 kmalloc_size_index[24] __ro_after_init = {
3, /* 8 */
4, /* 16 */
5, /* 24 */
5, /* 32 */
6, /* 40 */
6, /* 48 */
6, /* 56 */
6, /* 64 */
1, /* 72 */
1, /* 80 */
1, /* 88 */
1, /* 96 */
7, /* 104 */
7, /* 112 */
7, /* 120 */
7, /* 128 */
2, /* 136 */
2, /* 144 */
2, /* 152 */
2, /* 160 */
2, /* 168 */
2, /* 176 */
2, /* 184 */
2 /* 192 */
};
size_t kmalloc_size_roundup(size_t size)
{
if (size && size <= KMALLOC_MAX_CACHE_SIZE) {
/*
* The flags don't matter since size_index is common to all.
* Neither does the caller for just getting ->object_size.
*/
return kmalloc_slab(size, NULL, GFP_KERNEL, 0)->object_size;
}
/* Above the smaller buckets, size is a multiple of page size. */
if (size && size <= KMALLOC_MAX_SIZE)
return PAGE_SIZE << get_order(size);
/*
* Return 'size' for 0 - kmalloc() returns ZERO_SIZE_PTR
* and very large size - kmalloc() may fail.
*/
return size;
}
EXPORT_SYMBOL(kmalloc_size_roundup);
#ifdef CONFIG_ZONE_DMA
#define KMALLOC_DMA_NAME(sz) .name[KMALLOC_DMA] = "dma-kmalloc-" #sz,
#else
#define KMALLOC_DMA_NAME(sz)
#endif
#ifdef CONFIG_MEMCG
#define KMALLOC_CGROUP_NAME(sz) .name[KMALLOC_CGROUP] = "kmalloc-cg-" #sz,
#else
#define KMALLOC_CGROUP_NAME(sz)
#endif
#ifndef CONFIG_SLUB_TINY
#define KMALLOC_RCL_NAME(sz) .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #sz,
#else
#define KMALLOC_RCL_NAME(sz)
#endif
#ifdef CONFIG_RANDOM_KMALLOC_CACHES
#define __KMALLOC_RANDOM_CONCAT(a, b) a ## b
#define KMALLOC_RANDOM_NAME(N, sz) __KMALLOC_RANDOM_CONCAT(KMA_RAND_, N)(sz)
#define KMA_RAND_1(sz) .name[KMALLOC_RANDOM_START + 1] = "kmalloc-rnd-01-" #sz,
#define KMA_RAND_2(sz) KMA_RAND_1(sz) .name[KMALLOC_RANDOM_START + 2] = "kmalloc-rnd-02-" #sz,
#define KMA_RAND_3(sz) KMA_RAND_2(sz) .name[KMALLOC_RANDOM_START + 3] = "kmalloc-rnd-03-" #sz,
#define KMA_RAND_4(sz) KMA_RAND_3(sz) .name[KMALLOC_RANDOM_START + 4] = "kmalloc-rnd-04-" #sz,
#define KMA_RAND_5(sz) KMA_RAND_4(sz) .name[KMALLOC_RANDOM_START + 5] = "kmalloc-rnd-05-" #sz,
#define KMA_RAND_6(sz) KMA_RAND_5(sz) .name[KMALLOC_RANDOM_START + 6] = "kmalloc-rnd-06-" #sz,
#define KMA_RAND_7(sz) KMA_RAND_6(sz) .name[KMALLOC_RANDOM_START + 7] = "kmalloc-rnd-07-" #sz,
#define KMA_RAND_8(sz) KMA_RAND_7(sz) .name[KMALLOC_RANDOM_START + 8] = "kmalloc-rnd-08-" #sz,
#define KMA_RAND_9(sz) KMA_RAND_8(sz) .name[KMALLOC_RANDOM_START + 9] = "kmalloc-rnd-09-" #sz,
#define KMA_RAND_10(sz) KMA_RAND_9(sz) .name[KMALLOC_RANDOM_START + 10] = "kmalloc-rnd-10-" #sz,
#define KMA_RAND_11(sz) KMA_RAND_10(sz) .name[KMALLOC_RANDOM_START + 11] = "kmalloc-rnd-11-" #sz,
#define KMA_RAND_12(sz) KMA_RAND_11(sz) .name[KMALLOC_RANDOM_START + 12] = "kmalloc-rnd-12-" #sz,
#define KMA_RAND_13(sz) KMA_RAND_12(sz) .name[KMALLOC_RANDOM_START + 13] = "kmalloc-rnd-13-" #sz,
#define KMA_RAND_14(sz) KMA_RAND_13(sz) .name[KMALLOC_RANDOM_START + 14] = "kmalloc-rnd-14-" #sz,
#define KMA_RAND_15(sz) KMA_RAND_14(sz) .name[KMALLOC_RANDOM_START + 15] = "kmalloc-rnd-15-" #sz,
#else // CONFIG_RANDOM_KMALLOC_CACHES
#define KMALLOC_RANDOM_NAME(N, sz)
#endif
#define INIT_KMALLOC_INFO(__size, __short_size) \
{ \
.name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \
KMALLOC_RCL_NAME(__short_size) \
KMALLOC_CGROUP_NAME(__short_size) \
KMALLOC_DMA_NAME(__short_size) \
KMALLOC_RANDOM_NAME(RANDOM_KMALLOC_CACHES_NR, __short_size) \
.size = __size, \
}
/*
* kmalloc_info[] is to make slab_debug=,kmalloc-xx option work at boot time.
* kmalloc_index() supports up to 2^21=2MB, so the final entry of the table is
* kmalloc-2M.
*/
const struct kmalloc_info_struct kmalloc_info[] __initconst = {
INIT_KMALLOC_INFO(0, 0),
INIT_KMALLOC_INFO(96, 96),
INIT_KMALLOC_INFO(192, 192),
INIT_KMALLOC_INFO(8, 8),
INIT_KMALLOC_INFO(16, 16),
INIT_KMALLOC_INFO(32, 32),
INIT_KMALLOC_INFO(64, 64),
INIT_KMALLOC_INFO(128, 128),
INIT_KMALLOC_INFO(256, 256),
INIT_KMALLOC_INFO(512, 512),
INIT_KMALLOC_INFO(1024, 1k),
INIT_KMALLOC_INFO(2048, 2k),
INIT_KMALLOC_INFO(4096, 4k),
INIT_KMALLOC_INFO(8192, 8k),
INIT_KMALLOC_INFO(16384, 16k),
INIT_KMALLOC_INFO(32768, 32k),
INIT_KMALLOC_INFO(65536, 64k),
INIT_KMALLOC_INFO(131072, 128k),
INIT_KMALLOC_INFO(262144, 256k),
INIT_KMALLOC_INFO(524288, 512k),
INIT_KMALLOC_INFO(1048576, 1M),
INIT_KMALLOC_INFO(2097152, 2M)
};
/*
* Patch up the size_index table if we have strange large alignment
* requirements for the kmalloc array. This is only the case for
* MIPS it seems. The standard arches will not generate any code here.
*
* Largest permitted alignment is 256 bytes due to the way we
* handle the index determination for the smaller caches.
*
* Make sure that nothing crazy happens if someone starts tinkering
* around with ARCH_KMALLOC_MINALIGN
*/
void __init setup_kmalloc_cache_index_table(void)
{
unsigned int i;
BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
!is_power_of_2(KMALLOC_MIN_SIZE));
for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
unsigned int elem = size_index_elem(i);
if (elem >= ARRAY_SIZE(kmalloc_size_index))
break;
kmalloc_size_index[elem] = KMALLOC_SHIFT_LOW;
}
if (KMALLOC_MIN_SIZE >= 64) {
/*
* The 96 byte sized cache is not used if the alignment
* is 64 byte.
*/
for (i = 64 + 8; i <= 96; i += 8)
kmalloc_size_index[size_index_elem(i)] = 7;
}
if (KMALLOC_MIN_SIZE >= 128) {
/*
* The 192 byte sized cache is not used if the alignment
* is 128 byte. Redirect kmalloc to use the 256 byte cache
* instead.
*/
for (i = 128 + 8; i <= 192; i += 8)
kmalloc_size_index[size_index_elem(i)] = 8;
}
}
static unsigned int __kmalloc_minalign(void)
{
unsigned int minalign = dma_get_cache_alignment();
if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) &&
is_swiotlb_allocated())
minalign = ARCH_KMALLOC_MINALIGN;
return max(minalign, arch_slab_minalign());
}
static void __init
new_kmalloc_cache(int idx, enum kmalloc_cache_type type)
{
slab_flags_t flags = 0;
unsigned int minalign = __kmalloc_minalign();
unsigned int aligned_size = kmalloc_info[idx].size;
int aligned_idx = idx;
if ((KMALLOC_RECLAIM != KMALLOC_NORMAL) && (type == KMALLOC_RECLAIM)) {
flags |= SLAB_RECLAIM_ACCOUNT;
} else if (IS_ENABLED(CONFIG_MEMCG) && (type == KMALLOC_CGROUP)) {
if (mem_cgroup_kmem_disabled()) {
kmalloc_caches[type][idx] = kmalloc_caches[KMALLOC_NORMAL][idx];
return;
}
flags |= SLAB_ACCOUNT;
} else if (IS_ENABLED(CONFIG_ZONE_DMA) && (type == KMALLOC_DMA)) {
flags |= SLAB_CACHE_DMA;
}
#ifdef CONFIG_RANDOM_KMALLOC_CACHES
if (type >= KMALLOC_RANDOM_START && type <= KMALLOC_RANDOM_END)
flags |= SLAB_NO_MERGE;
#endif
/*
* If CONFIG_MEMCG is enabled, disable cache merging for
* KMALLOC_NORMAL caches.
*/
if (IS_ENABLED(CONFIG_MEMCG) && (type == KMALLOC_NORMAL))
flags |= SLAB_NO_MERGE;
if (minalign > ARCH_KMALLOC_MINALIGN) {
aligned_size = ALIGN(aligned_size, minalign);
aligned_idx = __kmalloc_index(aligned_size, false);
}
if (!kmalloc_caches[type][aligned_idx])
kmalloc_caches[type][aligned_idx] = create_kmalloc_cache(
kmalloc_info[aligned_idx].name[type],
aligned_size, flags);
if (idx != aligned_idx)
kmalloc_caches[type][idx] = kmalloc_caches[type][aligned_idx];
}
/*
* Create the kmalloc array. Some of the regular kmalloc arrays
* may already have been created because they were needed to
* enable allocations for slab creation.
*/
void __init create_kmalloc_caches(void)
{
int i;
enum kmalloc_cache_type type;
/*
* Including KMALLOC_CGROUP if CONFIG_MEMCG defined
*/
for (type = KMALLOC_NORMAL; type < NR_KMALLOC_TYPES; type++) {
/* Caches that are NOT of the two-to-the-power-of size. */
if (KMALLOC_MIN_SIZE <= 32)
new_kmalloc_cache(1, type);
if (KMALLOC_MIN_SIZE <= 64)
new_kmalloc_cache(2, type);
/* Caches that are of the two-to-the-power-of size. */
for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++)
new_kmalloc_cache(i, type);
}
#ifdef CONFIG_RANDOM_KMALLOC_CACHES
random_kmalloc_seed = get_random_u64();
#endif
/* Kmalloc array is now usable */
slab_state = UP;
if (IS_ENABLED(CONFIG_SLAB_BUCKETS))
kmem_buckets_cache = kmem_cache_create("kmalloc_buckets",
sizeof(kmem_buckets),
0, SLAB_NO_MERGE, NULL);
}
/**
* __ksize -- Report full size of underlying allocation
* @object: pointer to the object
*
* This should only be used internally to query the true size of allocations.
* It is not meant to be a way to discover the usable size of an allocation
* after the fact. Instead, use kmalloc_size_roundup(). Using memory beyond
* the originally requested allocation size may trigger KASAN, UBSAN_BOUNDS,
* and/or FORTIFY_SOURCE.
*
* Return: size of the actual memory used by @object in bytes
*/
size_t __ksize(const void *object)
{
struct folio *folio;
if (unlikely(object == ZERO_SIZE_PTR))
return 0;
folio = virt_to_folio(object);
if (unlikely(!folio_test_slab(folio))) {
if (WARN_ON(folio_size(folio) <= KMALLOC_MAX_CACHE_SIZE))
return 0;
if (WARN_ON(object != folio_address(folio)))
return 0;
return folio_size(folio);
}
#ifdef CONFIG_SLUB_DEBUG
skip_orig_size_check(folio_slab(folio)->slab_cache, object);
#endif
return slab_ksize(folio_slab(folio)->slab_cache);
}
gfp_t kmalloc_fix_flags(gfp_t flags)
{
gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
flags &= ~GFP_SLAB_BUG_MASK;
pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
invalid_mask, &invalid_mask, flags, &flags);
dump_stack();
return flags;
}
#ifdef CONFIG_SLAB_FREELIST_RANDOM
/* Randomize a generic freelist */
static void freelist_randomize(unsigned int *list,
unsigned int count)
{
unsigned int rand;
unsigned int i;
for (i = 0; i < count; i++)
list[i] = i;
/* Fisher-Yates shuffle */
for (i = count - 1; i > 0; i--) {
rand = get_random_u32_below(i + 1);
swap(list[i], list[rand]);
}
}
/* Create a random sequence per cache */
int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count,
gfp_t gfp)
{
if (count < 2 || cachep->random_seq)
return 0;
cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp);
if (!cachep->random_seq)
return -ENOMEM;
freelist_randomize(cachep->random_seq, count);
return 0;
}
/* Destroy the per-cache random freelist sequence */
void cache_random_seq_destroy(struct kmem_cache *cachep)
{
kfree(cachep->random_seq);
cachep->random_seq = NULL;
}
#endif /* CONFIG_SLAB_FREELIST_RANDOM */
#ifdef CONFIG_SLUB_DEBUG
#define SLABINFO_RIGHTS (0400)
static void print_slabinfo_header(struct seq_file *m)
{
/*
* Output format version, so at least we can change it
* without _too_ many complaints.
*/
seq_puts(m, "slabinfo - version: 2.1\n");
seq_puts(m, "# name <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");
seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
seq_putc(m, '\n');
}
static void *slab_start(struct seq_file *m, loff_t *pos)
{
mutex_lock(&slab_mutex);
return seq_list_start(&slab_caches, *pos);
}
static void *slab_next(struct seq_file *m, void *p, loff_t *pos)
{
return seq_list_next(p, &slab_caches, pos);
}
static void slab_stop(struct seq_file *m, void *p)
{
mutex_unlock(&slab_mutex);
}
static void cache_show(struct kmem_cache *s, struct seq_file *m)
{
struct slabinfo sinfo;
memset(&sinfo, 0, sizeof(sinfo));
get_slabinfo(s, &sinfo);
seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
s->name, sinfo.active_objs, sinfo.num_objs, s->size,
sinfo.objects_per_slab, (1 << sinfo.cache_order));
seq_printf(m, " : tunables %4u %4u %4u",
sinfo.limit, sinfo.batchcount, sinfo.shared);
seq_printf(m, " : slabdata %6lu %6lu %6lu",
sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
seq_putc(m, '\n');
}
static int slab_show(struct seq_file *m, void *p)
{
struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
if (p == slab_caches.next)
print_slabinfo_header(m);
cache_show(s, m);
return 0;
}
void dump_unreclaimable_slab(void)
{
struct kmem_cache *s;
struct slabinfo sinfo;
/*
* Here acquiring slab_mutex is risky since we don't prefer to get
* sleep in oom path. But, without mutex hold, it may introduce a
* risk of crash.
* Use mutex_trylock to protect the list traverse, dump nothing
* without acquiring the mutex.
*/
if (!mutex_trylock(&slab_mutex)) {
pr_warn("excessive unreclaimable slab but cannot dump stats\n");
return;
}
pr_info("Unreclaimable slab info:\n");
pr_info("Name Used Total\n");
list_for_each_entry(s, &slab_caches, list) {
if (s->flags & SLAB_RECLAIM_ACCOUNT)
continue;
get_slabinfo(s, &sinfo);
if (sinfo.num_objs > 0)
pr_info("%-17s %10luKB %10luKB\n", s->name,
(sinfo.active_objs * s->size) / 1024,
(sinfo.num_objs * s->size) / 1024);
}
mutex_unlock(&slab_mutex);
}
/*
* slabinfo_op - iterator that generates /proc/slabinfo
*
* Output layout:
* cache-name
* num-active-objs
* total-objs
* object size
* num-active-slabs
* total-slabs
* num-pages-per-slab
* + further values on SMP and with statistics enabled
*/
static const struct seq_operations slabinfo_op = {
.start = slab_start,
.next = slab_next,
.stop = slab_stop,
.show = slab_show,
};
static int slabinfo_open(struct inode *inode, struct file *file)
{
return seq_open(file, &slabinfo_op);
}
static const struct proc_ops slabinfo_proc_ops = {
.proc_flags = PROC_ENTRY_PERMANENT,
.proc_open = slabinfo_open,
.proc_read = seq_read,
.proc_lseek = seq_lseek,
.proc_release = seq_release,
};
static int __init slab_proc_init(void)
{
proc_create("slabinfo", SLABINFO_RIGHTS, NULL, &slabinfo_proc_ops);
return 0;
}
module_init(slab_proc_init);
#endif /* CONFIG_SLUB_DEBUG */
/**
* kfree_sensitive - Clear sensitive information in memory before freeing
* @p: object to free memory of
*
* The memory of the object @p points to is zeroed before freed.
* If @p is %NULL, kfree_sensitive() does nothing.
*
* Note: this function zeroes the whole allocated buffer which can be a good
* deal bigger than the requested buffer size passed to kmalloc(). So be
* careful when using this function in performance sensitive code.
*/
void kfree_sensitive(const void *p)
{
size_t ks;
void *mem = (void *)p;
ks = ksize(mem);
if (ks) {
kasan_unpoison_range(mem, ks);
memzero_explicit(mem, ks);
}
kfree(mem);
}
EXPORT_SYMBOL(kfree_sensitive);
size_t ksize(const void *objp)
{
/*
* We need to first check that the pointer to the object is valid.
* The KASAN report printed from ksize() is more useful, then when
* it's printed later when the behaviour could be undefined due to
* a potential use-after-free or double-free.
*
* We use kasan_check_byte(), which is supported for the hardware
* tag-based KASAN mode, unlike kasan_check_read/write().
*
* If the pointed to memory is invalid, we return 0 to avoid users of
* ksize() writing to and potentially corrupting the memory region.
*
* We want to perform the check before __ksize(), to avoid potentially
* crashing in __ksize() due to accessing invalid metadata.
*/
if (unlikely(ZERO_OR_NULL_PTR(objp)) || !kasan_check_byte(objp))
return 0;
return kfence_ksize(objp) ?: __ksize(objp);
}
EXPORT_SYMBOL(ksize);
#ifdef CONFIG_BPF_SYSCALL
#include <linux/btf.h>
__bpf_kfunc_start_defs();
__bpf_kfunc struct kmem_cache *bpf_get_kmem_cache(u64 addr)
{
struct slab *slab;
if (!virt_addr_valid((void *)(long)addr))
return NULL;
slab = virt_to_slab((void *)(long)addr);
return slab ? slab->slab_cache : NULL;
}
__bpf_kfunc_end_defs();
#endif /* CONFIG_BPF_SYSCALL */
/* Tracepoints definitions. */
EXPORT_TRACEPOINT_SYMBOL(kmalloc);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
EXPORT_TRACEPOINT_SYMBOL(kfree);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);
/*
* This rcu parameter is runtime-read-only. It reflects
* a minimum allowed number of objects which can be cached
* per-CPU. Object size is equal to one page. This value
* can be changed at boot time.
*/
static int rcu_min_cached_objs = 5;
module_param(rcu_min_cached_objs, int, 0444);
// A page shrinker can ask for pages to be freed to make them
// available for other parts of the system. This usually happens
// under low memory conditions, and in that case we should also
// defer page-cache filling for a short time period.
//
// The default value is 5 seconds, which is long enough to reduce
// interference with the shrinker while it asks other systems to
// drain their caches.
static int rcu_delay_page_cache_fill_msec = 5000;
module_param(rcu_delay_page_cache_fill_msec, int, 0444);
/* Maximum number of jiffies to wait before draining a batch. */
#define KFREE_DRAIN_JIFFIES (5 * HZ)
#define KFREE_N_BATCHES 2
#define FREE_N_CHANNELS 2
/**
* struct kvfree_rcu_bulk_data - single block to store kvfree_rcu() pointers
* @list: List node. All blocks are linked between each other
* @gp_snap: Snapshot of RCU state for objects placed to this bulk
* @nr_records: Number of active pointers in the array
* @records: Array of the kvfree_rcu() pointers
*/
struct kvfree_rcu_bulk_data {
struct list_head list;
struct rcu_gp_oldstate gp_snap;
unsigned long nr_records;
void *records[] __counted_by(nr_records);
};
/*
* This macro defines how many entries the "records" array
* will contain. It is based on the fact that the size of
* kvfree_rcu_bulk_data structure becomes exactly one page.
*/
#define KVFREE_BULK_MAX_ENTR \
((PAGE_SIZE - sizeof(struct kvfree_rcu_bulk_data)) / sizeof(void *))
/**
* struct kfree_rcu_cpu_work - single batch of kfree_rcu() requests
* @rcu_work: Let queue_rcu_work() invoke workqueue handler after grace period
* @head_free: List of kfree_rcu() objects waiting for a grace period
* @head_free_gp_snap: Grace-period snapshot to check for attempted premature frees.
* @bulk_head_free: Bulk-List of kvfree_rcu() objects waiting for a grace period
* @krcp: Pointer to @kfree_rcu_cpu structure
*/
struct kfree_rcu_cpu_work {
struct rcu_work rcu_work;
struct rcu_head *head_free;
struct rcu_gp_oldstate head_free_gp_snap;
struct list_head bulk_head_free[FREE_N_CHANNELS];
struct kfree_rcu_cpu *krcp;
};
/**
* struct kfree_rcu_cpu - batch up kfree_rcu() requests for RCU grace period
* @head: List of kfree_rcu() objects not yet waiting for a grace period
* @head_gp_snap: Snapshot of RCU state for objects placed to "@head"
* @bulk_head: Bulk-List of kvfree_rcu() objects not yet waiting for a grace period
* @krw_arr: Array of batches of kfree_rcu() objects waiting for a grace period
* @lock: Synchronize access to this structure
* @monitor_work: Promote @head to @head_free after KFREE_DRAIN_JIFFIES
* @initialized: The @rcu_work fields have been initialized
* @head_count: Number of objects in rcu_head singular list
* @bulk_count: Number of objects in bulk-list
* @bkvcache:
* A simple cache list that contains objects for reuse purpose.
* In order to save some per-cpu space the list is singular.
* Even though it is lockless an access has to be protected by the
* per-cpu lock.
* @page_cache_work: A work to refill the cache when it is empty
* @backoff_page_cache_fill: Delay cache refills
* @work_in_progress: Indicates that page_cache_work is running
* @hrtimer: A hrtimer for scheduling a page_cache_work
* @nr_bkv_objs: number of allocated objects at @bkvcache.
*
* This is a per-CPU structure. The reason that it is not included in
* the rcu_data structure is to permit this code to be extracted from
* the RCU files. Such extraction could allow further optimization of
* the interactions with the slab allocators.
*/
struct kfree_rcu_cpu {
// Objects queued on a linked list
// through their rcu_head structures.
struct rcu_head *head;
unsigned long head_gp_snap;
atomic_t head_count;
// Objects queued on a bulk-list.
struct list_head bulk_head[FREE_N_CHANNELS];
atomic_t bulk_count[FREE_N_CHANNELS];
struct kfree_rcu_cpu_work krw_arr[KFREE_N_BATCHES];
raw_spinlock_t lock;
struct delayed_work monitor_work;
bool initialized;
struct delayed_work page_cache_work;
atomic_t backoff_page_cache_fill;
atomic_t work_in_progress;
struct hrtimer hrtimer;
struct llist_head bkvcache;
int nr_bkv_objs;
};
static DEFINE_PER_CPU(struct kfree_rcu_cpu, krc) = {
.lock = __RAW_SPIN_LOCK_UNLOCKED(krc.lock),
};
static __always_inline void
debug_rcu_bhead_unqueue(struct kvfree_rcu_bulk_data *bhead)
{
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
int i;
for (i = 0; i < bhead->nr_records; i++)
debug_rcu_head_unqueue((struct rcu_head *)(bhead->records[i]));
#endif
}
static inline struct kfree_rcu_cpu *
krc_this_cpu_lock(unsigned long *flags)
{
struct kfree_rcu_cpu *krcp;
local_irq_save(*flags); // For safely calling this_cpu_ptr().
krcp = this_cpu_ptr(&krc);
raw_spin_lock(&krcp->lock);
return krcp;
}
static inline void
krc_this_cpu_unlock(struct kfree_rcu_cpu *krcp, unsigned long flags)
{
raw_spin_unlock_irqrestore(&krcp->lock, flags);
}
static inline struct kvfree_rcu_bulk_data *
get_cached_bnode(struct kfree_rcu_cpu *krcp)
{
if (!krcp->nr_bkv_objs)
return NULL;
WRITE_ONCE(krcp->nr_bkv_objs, krcp->nr_bkv_objs - 1);
return (struct kvfree_rcu_bulk_data *)
llist_del_first(&krcp->bkvcache);
}
static inline bool
put_cached_bnode(struct kfree_rcu_cpu *krcp,
struct kvfree_rcu_bulk_data *bnode)
{
// Check the limit.
if (krcp->nr_bkv_objs >= rcu_min_cached_objs)
return false;
llist_add((struct llist_node *) bnode, &krcp->bkvcache);
WRITE_ONCE(krcp->nr_bkv_objs, krcp->nr_bkv_objs + 1);
return true;
}
static int
drain_page_cache(struct kfree_rcu_cpu *krcp)
{
unsigned long flags;
struct llist_node *page_list, *pos, *n;
int freed = 0;
if (!rcu_min_cached_objs)
return 0;
raw_spin_lock_irqsave(&krcp->lock, flags);
page_list = llist_del_all(&krcp->bkvcache);
WRITE_ONCE(krcp->nr_bkv_objs, 0);
raw_spin_unlock_irqrestore(&krcp->lock, flags);
llist_for_each_safe(pos, n, page_list) {
free_page((unsigned long)pos);
freed++;
}
return freed;
}
static void
kvfree_rcu_bulk(struct kfree_rcu_cpu *krcp,
struct kvfree_rcu_bulk_data *bnode, int idx)
{
unsigned long flags;
int i;
if (!WARN_ON_ONCE(!poll_state_synchronize_rcu_full(&bnode->gp_snap))) {
debug_rcu_bhead_unqueue(bnode);
rcu_lock_acquire(&rcu_callback_map);
if (idx == 0) { // kmalloc() / kfree().
trace_rcu_invoke_kfree_bulk_callback(
"slab", bnode->nr_records,
bnode->records);
kfree_bulk(bnode->nr_records, bnode->records);
} else { // vmalloc() / vfree().
for (i = 0; i < bnode->nr_records; i++) {
trace_rcu_invoke_kvfree_callback(
"slab", bnode->records[i], 0);
vfree(bnode->records[i]);
}
}
rcu_lock_release(&rcu_callback_map);
}
raw_spin_lock_irqsave(&krcp->lock, flags);
if (put_cached_bnode(krcp, bnode))
bnode = NULL;
raw_spin_unlock_irqrestore(&krcp->lock, flags);
if (bnode)
free_page((unsigned long) bnode);
cond_resched_tasks_rcu_qs();
}
static void
kvfree_rcu_list(struct rcu_head *head)
{
struct rcu_head *next;
for (; head; head = next) {
void *ptr = (void *) head->func;
unsigned long offset = (void *) head - ptr;
next = head->next;
debug_rcu_head_unqueue((struct rcu_head *)ptr);
rcu_lock_acquire(&rcu_callback_map);
trace_rcu_invoke_kvfree_callback("slab", head, offset);
if (!WARN_ON_ONCE(!__is_kvfree_rcu_offset(offset)))
kvfree(ptr);
rcu_lock_release(&rcu_callback_map);
cond_resched_tasks_rcu_qs();
}
}
/*
* This function is invoked in workqueue context after a grace period.
* It frees all the objects queued on ->bulk_head_free or ->head_free.
*/
static void kfree_rcu_work(struct work_struct *work)
{
unsigned long flags;
struct kvfree_rcu_bulk_data *bnode, *n;
struct list_head bulk_head[FREE_N_CHANNELS];
struct rcu_head *head;
struct kfree_rcu_cpu *krcp;
struct kfree_rcu_cpu_work *krwp;
struct rcu_gp_oldstate head_gp_snap;
int i;
krwp = container_of(to_rcu_work(work),
struct kfree_rcu_cpu_work, rcu_work);
krcp = krwp->krcp;
raw_spin_lock_irqsave(&krcp->lock, flags);
// Channels 1 and 2.
for (i = 0; i < FREE_N_CHANNELS; i++)
list_replace_init(&krwp->bulk_head_free[i], &bulk_head[i]);
// Channel 3.
head = krwp->head_free;
krwp->head_free = NULL;
head_gp_snap = krwp->head_free_gp_snap;
raw_spin_unlock_irqrestore(&krcp->lock, flags);
// Handle the first two channels.
for (i = 0; i < FREE_N_CHANNELS; i++) {
// Start from the tail page, so a GP is likely passed for it.
list_for_each_entry_safe(bnode, n, &bulk_head[i], list)
kvfree_rcu_bulk(krcp, bnode, i);
}
/*
* This is used when the "bulk" path can not be used for the
* double-argument of kvfree_rcu(). This happens when the
* page-cache is empty, which means that objects are instead
* queued on a linked list through their rcu_head structures.
* This list is named "Channel 3".
*/
if (head && !WARN_ON_ONCE(!poll_state_synchronize_rcu_full(&head_gp_snap)))
kvfree_rcu_list(head);
}
static bool
need_offload_krc(struct kfree_rcu_cpu *krcp)
{
int i;
for (i = 0; i < FREE_N_CHANNELS; i++)
if (!list_empty(&krcp->bulk_head[i]))
return true;
return !!READ_ONCE(krcp->head);
}
static bool
need_wait_for_krwp_work(struct kfree_rcu_cpu_work *krwp)
{
int i;
for (i = 0; i < FREE_N_CHANNELS; i++)
if (!list_empty(&krwp->bulk_head_free[i]))
return true;
return !!krwp->head_free;
}
static int krc_count(struct kfree_rcu_cpu *krcp)
{
int sum = atomic_read(&krcp->head_count);
int i;
for (i = 0; i < FREE_N_CHANNELS; i++)
sum += atomic_read(&krcp->bulk_count[i]);
return sum;
}
static void
__schedule_delayed_monitor_work(struct kfree_rcu_cpu *krcp)
{
long delay, delay_left;
delay = krc_count(krcp) >= KVFREE_BULK_MAX_ENTR ? 1:KFREE_DRAIN_JIFFIES;
if (delayed_work_pending(&krcp->monitor_work)) {
delay_left = krcp->monitor_work.timer.expires - jiffies;
if (delay < delay_left)
mod_delayed_work(system_unbound_wq, &krcp->monitor_work, delay);
return;
}
queue_delayed_work(system_unbound_wq, &krcp->monitor_work, delay);
}
static void
schedule_delayed_monitor_work(struct kfree_rcu_cpu *krcp)
{
unsigned long flags;
raw_spin_lock_irqsave(&krcp->lock, flags);
__schedule_delayed_monitor_work(krcp);
raw_spin_unlock_irqrestore(&krcp->lock, flags);
}
static void
kvfree_rcu_drain_ready(struct kfree_rcu_cpu *krcp)
{
struct list_head bulk_ready[FREE_N_CHANNELS];
struct kvfree_rcu_bulk_data *bnode, *n;
struct rcu_head *head_ready = NULL;
unsigned long flags;
int i;
raw_spin_lock_irqsave(&krcp->lock, flags);
for (i = 0; i < FREE_N_CHANNELS; i++) {
INIT_LIST_HEAD(&bulk_ready[i]);
list_for_each_entry_safe_reverse(bnode, n, &krcp->bulk_head[i], list) {
if (!poll_state_synchronize_rcu_full(&bnode->gp_snap))
break;
atomic_sub(bnode->nr_records, &krcp->bulk_count[i]);
list_move(&bnode->list, &bulk_ready[i]);
}
}
if (krcp->head && poll_state_synchronize_rcu(krcp->head_gp_snap)) {
head_ready = krcp->head;
atomic_set(&krcp->head_count, 0);
WRITE_ONCE(krcp->head, NULL);
}
raw_spin_unlock_irqrestore(&krcp->lock, flags);
for (i = 0; i < FREE_N_CHANNELS; i++) {
list_for_each_entry_safe(bnode, n, &bulk_ready[i], list)
kvfree_rcu_bulk(krcp, bnode, i);
}
if (head_ready)
kvfree_rcu_list(head_ready);
}
/*
* Return: %true if a work is queued, %false otherwise.
*/
static bool
kvfree_rcu_queue_batch(struct kfree_rcu_cpu *krcp)
{
unsigned long flags;
bool queued = false;
int i, j;
raw_spin_lock_irqsave(&krcp->lock, flags);
// Attempt to start a new batch.
for (i = 0; i < KFREE_N_BATCHES; i++) {
struct kfree_rcu_cpu_work *krwp = &(krcp->krw_arr[i]);
// Try to detach bulk_head or head and attach it, only when
// all channels are free. Any channel is not free means at krwp
// there is on-going rcu work to handle krwp's free business.
if (need_wait_for_krwp_work(krwp))
continue;
// kvfree_rcu_drain_ready() might handle this krcp, if so give up.
if (need_offload_krc(krcp)) {
// Channel 1 corresponds to the SLAB-pointer bulk path.
// Channel 2 corresponds to vmalloc-pointer bulk path.
for (j = 0; j < FREE_N_CHANNELS; j++) {
if (list_empty(&krwp->bulk_head_free[j])) {
atomic_set(&krcp->bulk_count[j], 0);
list_replace_init(&krcp->bulk_head[j],
&krwp->bulk_head_free[j]);
}
}
// Channel 3 corresponds to both SLAB and vmalloc
// objects queued on the linked list.
if (!krwp->head_free) {
krwp->head_free = krcp->head;
get_state_synchronize_rcu_full(&krwp->head_free_gp_snap);
atomic_set(&krcp->head_count, 0);
WRITE_ONCE(krcp->head, NULL);
}
// One work is per one batch, so there are three
// "free channels", the batch can handle. Break
// the loop since it is done with this CPU thus
// queuing an RCU work is _always_ success here.
queued = queue_rcu_work(system_unbound_wq, &krwp->rcu_work);
WARN_ON_ONCE(!queued);
break;
}
}
raw_spin_unlock_irqrestore(&krcp->lock, flags);
return queued;
}
/*
* This function is invoked after the KFREE_DRAIN_JIFFIES timeout.
*/
static void kfree_rcu_monitor(struct work_struct *work)
{
struct kfree_rcu_cpu *krcp = container_of(work,
struct kfree_rcu_cpu, monitor_work.work);
// Drain ready for reclaim.
kvfree_rcu_drain_ready(krcp);
// Queue a batch for a rest.
kvfree_rcu_queue_batch(krcp);
// If there is nothing to detach, it means that our job is
// successfully done here. In case of having at least one
// of the channels that is still busy we should rearm the
// work to repeat an attempt. Because previous batches are
// still in progress.
if (need_offload_krc(krcp))
schedule_delayed_monitor_work(krcp);
}
static void fill_page_cache_func(struct work_struct *work)
{
struct kvfree_rcu_bulk_data *bnode;
struct kfree_rcu_cpu *krcp =
container_of(work, struct kfree_rcu_cpu,
page_cache_work.work);
unsigned long flags;
int nr_pages;
bool pushed;
int i;
nr_pages = atomic_read(&krcp->backoff_page_cache_fill) ?
1 : rcu_min_cached_objs;
for (i = READ_ONCE(krcp->nr_bkv_objs); i < nr_pages; i++) {
bnode = (struct kvfree_rcu_bulk_data *)
__get_free_page(GFP_KERNEL | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
if (!bnode)
break;
raw_spin_lock_irqsave(&krcp->lock, flags);
pushed = put_cached_bnode(krcp, bnode);
raw_spin_unlock_irqrestore(&krcp->lock, flags);
if (!pushed) {
free_page((unsigned long) bnode);
break;
}
}
atomic_set(&krcp->work_in_progress, 0);
atomic_set(&krcp->backoff_page_cache_fill, 0);
}
// Record ptr in a page managed by krcp, with the pre-krc_this_cpu_lock()
// state specified by flags. If can_alloc is true, the caller must
// be schedulable and not be holding any locks or mutexes that might be
// acquired by the memory allocator or anything that it might invoke.
// Returns true if ptr was successfully recorded, else the caller must
// use a fallback.
static inline bool
add_ptr_to_bulk_krc_lock(struct kfree_rcu_cpu **krcp,
unsigned long *flags, void *ptr, bool can_alloc)
{
struct kvfree_rcu_bulk_data *bnode;
int idx;
*krcp = krc_this_cpu_lock(flags);
if (unlikely(!(*krcp)->initialized))
return false;
idx = !!is_vmalloc_addr(ptr);
bnode = list_first_entry_or_null(&(*krcp)->bulk_head[idx],
struct kvfree_rcu_bulk_data, list);
/* Check if a new block is required. */
if (!bnode || bnode->nr_records == KVFREE_BULK_MAX_ENTR) {
bnode = get_cached_bnode(*krcp);
if (!bnode && can_alloc) {
krc_this_cpu_unlock(*krcp, *flags);
// __GFP_NORETRY - allows a light-weight direct reclaim
// what is OK from minimizing of fallback hitting point of
// view. Apart of that it forbids any OOM invoking what is
// also beneficial since we are about to release memory soon.
//
// __GFP_NOMEMALLOC - prevents from consuming of all the
// memory reserves. Please note we have a fallback path.
//
// __GFP_NOWARN - it is supposed that an allocation can
// be failed under low memory or high memory pressure
// scenarios.
bnode = (struct kvfree_rcu_bulk_data *)
__get_free_page(GFP_KERNEL | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
raw_spin_lock_irqsave(&(*krcp)->lock, *flags);
}
if (!bnode)
return false;
// Initialize the new block and attach it.
bnode->nr_records = 0;
list_add(&bnode->list, &(*krcp)->bulk_head[idx]);
}
// Finally insert and update the GP for this page.
bnode->nr_records++;
bnode->records[bnode->nr_records - 1] = ptr;
get_state_synchronize_rcu_full(&bnode->gp_snap);
atomic_inc(&(*krcp)->bulk_count[idx]);
return true;
}
#if !defined(CONFIG_TINY_RCU)
static enum hrtimer_restart
schedule_page_work_fn(struct hrtimer *t)
{
struct kfree_rcu_cpu *krcp =
container_of(t, struct kfree_rcu_cpu, hrtimer);
queue_delayed_work(system_highpri_wq, &krcp->page_cache_work, 0);
return HRTIMER_NORESTART;
}
static void
run_page_cache_worker(struct kfree_rcu_cpu *krcp)
{
// If cache disabled, bail out.
if (!rcu_min_cached_objs)
return;
if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING &&
!atomic_xchg(&krcp->work_in_progress, 1)) {
if (atomic_read(&krcp->backoff_page_cache_fill)) {
queue_delayed_work(system_unbound_wq,
&krcp->page_cache_work,
msecs_to_jiffies(rcu_delay_page_cache_fill_msec));
} else {
hrtimer_init(&krcp->hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
krcp->hrtimer.function = schedule_page_work_fn;
hrtimer_start(&krcp->hrtimer, 0, HRTIMER_MODE_REL);
}
}
}
void __init kfree_rcu_scheduler_running(void)
{
int cpu;
for_each_possible_cpu(cpu) {
struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);
if (need_offload_krc(krcp))
schedule_delayed_monitor_work(krcp);
}
}
/*
* Queue a request for lazy invocation of the appropriate free routine
* after a grace period. Please note that three paths are maintained,
* two for the common case using arrays of pointers and a third one that
* is used only when the main paths cannot be used, for example, due to
* memory pressure.
*
* Each kvfree_call_rcu() request is added to a batch. The batch will be drained
* every KFREE_DRAIN_JIFFIES number of jiffies. All the objects in the batch will
* be free'd in workqueue context. This allows us to: batch requests together to
* reduce the number of grace periods during heavy kfree_rcu()/kvfree_rcu() load.
*/
void kvfree_call_rcu(struct rcu_head *head, void *ptr)
{
unsigned long flags;
struct kfree_rcu_cpu *krcp;
bool success;
/*
* Please note there is a limitation for the head-less
* variant, that is why there is a clear rule for such
* objects: it can be used from might_sleep() context
* only. For other places please embed an rcu_head to
* your data.
*/
if (!head)
might_sleep();
// Queue the object but don't yet schedule the batch.
if (debug_rcu_head_queue(ptr)) {
// Probable double kfree_rcu(), just leak.
WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n",
__func__, head);
// Mark as success and leave.
return;
}
kasan_record_aux_stack(ptr);
success = add_ptr_to_bulk_krc_lock(&krcp, &flags, ptr, !head);
if (!success) {
run_page_cache_worker(krcp);
if (head == NULL)
// Inline if kvfree_rcu(one_arg) call.
goto unlock_return;
head->func = ptr;
head->next = krcp->head;
WRITE_ONCE(krcp->head, head);
atomic_inc(&krcp->head_count);
// Take a snapshot for this krcp.
krcp->head_gp_snap = get_state_synchronize_rcu();
success = true;
}
/*
* The kvfree_rcu() caller considers the pointer freed at this point
* and likely removes any references to it. Since the actual slab
* freeing (and kmemleak_free()) is deferred, tell kmemleak to ignore
* this object (no scanning or false positives reporting).
*/
kmemleak_ignore(ptr);
// Set timer to drain after KFREE_DRAIN_JIFFIES.
if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING)
__schedule_delayed_monitor_work(krcp);
unlock_return:
krc_this_cpu_unlock(krcp, flags);
/*
* Inline kvfree() after synchronize_rcu(). We can do
* it from might_sleep() context only, so the current
* CPU can pass the QS state.
*/
if (!success) {
debug_rcu_head_unqueue((struct rcu_head *) ptr);
synchronize_rcu();
kvfree(ptr);
}
}
EXPORT_SYMBOL_GPL(kvfree_call_rcu);
/**
* kvfree_rcu_barrier - Wait until all in-flight kvfree_rcu() complete.
*
* Note that a single argument of kvfree_rcu() call has a slow path that
* triggers synchronize_rcu() following by freeing a pointer. It is done
* before the return from the function. Therefore for any single-argument
* call that will result in a kfree() to a cache that is to be destroyed
* during module exit, it is developer's responsibility to ensure that all
* such calls have returned before the call to kmem_cache_destroy().
*/
void kvfree_rcu_barrier(void)
{
struct kfree_rcu_cpu_work *krwp;
struct kfree_rcu_cpu *krcp;
bool queued;
int i, cpu;
/*
* Firstly we detach objects and queue them over an RCU-batch
* for all CPUs. Finally queued works are flushed for each CPU.
*
* Please note. If there are outstanding batches for a particular
* CPU, those have to be finished first following by queuing a new.
*/
for_each_possible_cpu(cpu) {
krcp = per_cpu_ptr(&krc, cpu);
/*
* Check if this CPU has any objects which have been queued for a
* new GP completion. If not(means nothing to detach), we are done
* with it. If any batch is pending/running for this "krcp", below
* per-cpu flush_rcu_work() waits its completion(see last step).
*/
if (!need_offload_krc(krcp))
continue;
while (1) {
/*
* If we are not able to queue a new RCU work it means:
* - batches for this CPU are still in flight which should
* be flushed first and then repeat;
* - no objects to detach, because of concurrency.
*/
queued = kvfree_rcu_queue_batch(krcp);
/*
* Bail out, if there is no need to offload this "krcp"
* anymore. As noted earlier it can run concurrently.
*/
if (queued || !need_offload_krc(krcp))
break;
/* There are ongoing batches. */
for (i = 0; i < KFREE_N_BATCHES; i++) {
krwp = &(krcp->krw_arr[i]);
flush_rcu_work(&krwp->rcu_work);
}
}
}
/*
* Now we guarantee that all objects are flushed.
*/
for_each_possible_cpu(cpu) {
krcp = per_cpu_ptr(&krc, cpu);
/*
* A monitor work can drain ready to reclaim objects
* directly. Wait its completion if running or pending.
*/
cancel_delayed_work_sync(&krcp->monitor_work);
for (i = 0; i < KFREE_N_BATCHES; i++) {
krwp = &(krcp->krw_arr[i]);
flush_rcu_work(&krwp->rcu_work);
}
}
}
EXPORT_SYMBOL_GPL(kvfree_rcu_barrier);
#endif /* #if !defined(CONFIG_TINY_RCU) */
static unsigned long
kfree_rcu_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
{
int cpu;
unsigned long count = 0;
/* Snapshot count of all CPUs */
for_each_possible_cpu(cpu) {
struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);
count += krc_count(krcp);
count += READ_ONCE(krcp->nr_bkv_objs);
atomic_set(&krcp->backoff_page_cache_fill, 1);
}
return count == 0 ? SHRINK_EMPTY : count;
}
static unsigned long
kfree_rcu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
{
int cpu, freed = 0;
for_each_possible_cpu(cpu) {
int count;
struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);
count = krc_count(krcp);
count += drain_page_cache(krcp);
kfree_rcu_monitor(&krcp->monitor_work.work);
sc->nr_to_scan -= count;
freed += count;
if (sc->nr_to_scan <= 0)
break;
}
return freed == 0 ? SHRINK_STOP : freed;
}
void __init kvfree_rcu_init(void)
{
int cpu;
int i, j;
struct shrinker *kfree_rcu_shrinker;
/* Clamp it to [0:100] seconds interval. */
if (rcu_delay_page_cache_fill_msec < 0 ||
rcu_delay_page_cache_fill_msec > 100 * MSEC_PER_SEC) {
rcu_delay_page_cache_fill_msec =
clamp(rcu_delay_page_cache_fill_msec, 0,
(int) (100 * MSEC_PER_SEC));
pr_info("Adjusting rcutree.rcu_delay_page_cache_fill_msec to %d ms.\n",
rcu_delay_page_cache_fill_msec);
}
for_each_possible_cpu(cpu) {
struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);
for (i = 0; i < KFREE_N_BATCHES; i++) {
INIT_RCU_WORK(&krcp->krw_arr[i].rcu_work, kfree_rcu_work);
krcp->krw_arr[i].krcp = krcp;
for (j = 0; j < FREE_N_CHANNELS; j++)
INIT_LIST_HEAD(&krcp->krw_arr[i].bulk_head_free[j]);
}
for (i = 0; i < FREE_N_CHANNELS; i++)
INIT_LIST_HEAD(&krcp->bulk_head[i]);
INIT_DELAYED_WORK(&krcp->monitor_work, kfree_rcu_monitor);
INIT_DELAYED_WORK(&krcp->page_cache_work, fill_page_cache_func);
krcp->initialized = true;
}
kfree_rcu_shrinker = shrinker_alloc(0, "slab-kvfree-rcu");
if (!kfree_rcu_shrinker) {
pr_err("Failed to allocate kfree_rcu() shrinker!\n");
return;
}
kfree_rcu_shrinker->count_objects = kfree_rcu_shrink_count;
kfree_rcu_shrinker->scan_objects = kfree_rcu_shrink_scan;
shrinker_register(kfree_rcu_shrinker);
}