linux/mm/slab_common.c
Kees Cook 7660a6fddc mm: allow slab_nomerge to be set at build time
Some hardened environments want to build kernels with slab_nomerge
already set (so that they do not depend on remembering to set the kernel
command line option).  This is desired to reduce the risk of kernel heap
overflows being able to overwrite objects from merged caches and changes
the requirements for cache layout control, increasing the difficulty of
these attacks.  By keeping caches unmerged, these kinds of exploits can
usually only damage objects in the same cache (though the risk to
metadata exploitation is unchanged).

Link: http://lkml.kernel.org/r/20170620230911.GA25238@beast
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Daniel Micay <danielmicay@gmail.com>
Cc: David Windsor <dave@nullcore.net>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Daniel Micay <danielmicay@gmail.com>
Cc: David Windsor <dave@nullcore.net>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Daniel Mack <daniel@zonque.org>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-07-06 16:24:31 -07:00

1451 lines
34 KiB
C

/*
* 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/compiler.h>
#include <linux/module.h>
#include <linux/cpu.h>
#include <linux/uaccess.h>
#include <linux/seq_file.h>
#include <linux/proc_fs.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/page.h>
#include <linux/memcontrol.h>
#define CREATE_TRACE_POINTS
#include <trace/events/kmem.h>
#include "slab.h"
enum slab_state slab_state;
LIST_HEAD(slab_caches);
DEFINE_MUTEX(slab_mutex);
struct kmem_cache *kmem_cache;
static LIST_HEAD(slab_caches_to_rcu_destroy);
static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work);
static DECLARE_WORK(slab_caches_to_rcu_destroy_work,
slab_caches_to_rcu_destroy_workfn);
/*
* 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_KASAN)
#define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
SLAB_NOTRACK | 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;
}
#ifdef CONFIG_SLUB
__setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0);
#endif
__setup("slab_nomerge", setup_slab_nomerge);
/*
* 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 int kmem_cache_sanity_check(const char *name, size_t size)
{
struct kmem_cache *s = NULL;
if (!name || in_interrupt() || size < sizeof(void *) ||
size > KMALLOC_MAX_SIZE) {
pr_err("kmem_cache_create(%s) integrity check failed\n", name);
return -EINVAL;
}
list_for_each_entry(s, &slab_caches, list) {
char tmp;
int res;
/*
* This happens when the module gets unloaded and doesn't
* destroy its slab cache and no-one else reuses the vmalloc
* area of the module. Print a warning.
*/
res = probe_kernel_address(s->name, tmp);
if (res) {
pr_err("Slab cache with size %d has lost its name\n",
s->object_size);
continue;
}
}
WARN_ON(strchr(name, ' ')); /* It confuses parsers */
return 0;
}
#else
static inline int kmem_cache_sanity_check(const char *name, size_t size)
{
return 0;
}
#endif
void __kmem_cache_free_bulk(struct kmem_cache *s, size_t nr, void **p)
{
size_t i;
for (i = 0; i < nr; i++) {
if (s)
kmem_cache_free(s, p[i]);
else
kfree(p[i]);
}
}
int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t nr,
void **p)
{
size_t i;
for (i = 0; i < nr; i++) {
void *x = p[i] = kmem_cache_alloc(s, flags);
if (!x) {
__kmem_cache_free_bulk(s, i, p);
return 0;
}
}
return i;
}
#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
LIST_HEAD(slab_root_caches);
void slab_init_memcg_params(struct kmem_cache *s)
{
s->memcg_params.root_cache = NULL;
RCU_INIT_POINTER(s->memcg_params.memcg_caches, NULL);
INIT_LIST_HEAD(&s->memcg_params.children);
}
static int init_memcg_params(struct kmem_cache *s,
struct mem_cgroup *memcg, struct kmem_cache *root_cache)
{
struct memcg_cache_array *arr;
if (root_cache) {
s->memcg_params.root_cache = root_cache;
s->memcg_params.memcg = memcg;
INIT_LIST_HEAD(&s->memcg_params.children_node);
INIT_LIST_HEAD(&s->memcg_params.kmem_caches_node);
return 0;
}
slab_init_memcg_params(s);
if (!memcg_nr_cache_ids)
return 0;
arr = kzalloc(sizeof(struct memcg_cache_array) +
memcg_nr_cache_ids * sizeof(void *),
GFP_KERNEL);
if (!arr)
return -ENOMEM;
RCU_INIT_POINTER(s->memcg_params.memcg_caches, arr);
return 0;
}
static void destroy_memcg_params(struct kmem_cache *s)
{
if (is_root_cache(s))
kfree(rcu_access_pointer(s->memcg_params.memcg_caches));
}
static int update_memcg_params(struct kmem_cache *s, int new_array_size)
{
struct memcg_cache_array *old, *new;
new = kzalloc(sizeof(struct memcg_cache_array) +
new_array_size * sizeof(void *), GFP_KERNEL);
if (!new)
return -ENOMEM;
old = rcu_dereference_protected(s->memcg_params.memcg_caches,
lockdep_is_held(&slab_mutex));
if (old)
memcpy(new->entries, old->entries,
memcg_nr_cache_ids * sizeof(void *));
rcu_assign_pointer(s->memcg_params.memcg_caches, new);
if (old)
kfree_rcu(old, rcu);
return 0;
}
int memcg_update_all_caches(int num_memcgs)
{
struct kmem_cache *s;
int ret = 0;
mutex_lock(&slab_mutex);
list_for_each_entry(s, &slab_root_caches, root_caches_node) {
ret = update_memcg_params(s, num_memcgs);
/*
* Instead of freeing the memory, we'll just leave the caches
* up to this point in an updated state.
*/
if (ret)
break;
}
mutex_unlock(&slab_mutex);
return ret;
}
void memcg_link_cache(struct kmem_cache *s)
{
if (is_root_cache(s)) {
list_add(&s->root_caches_node, &slab_root_caches);
} else {
list_add(&s->memcg_params.children_node,
&s->memcg_params.root_cache->memcg_params.children);
list_add(&s->memcg_params.kmem_caches_node,
&s->memcg_params.memcg->kmem_caches);
}
}
static void memcg_unlink_cache(struct kmem_cache *s)
{
if (is_root_cache(s)) {
list_del(&s->root_caches_node);
} else {
list_del(&s->memcg_params.children_node);
list_del(&s->memcg_params.kmem_caches_node);
}
}
#else
static inline int init_memcg_params(struct kmem_cache *s,
struct mem_cgroup *memcg, struct kmem_cache *root_cache)
{
return 0;
}
static inline void destroy_memcg_params(struct kmem_cache *s)
{
}
static inline void memcg_unlink_cache(struct kmem_cache *s)
{
}
#endif /* CONFIG_MEMCG && !CONFIG_SLOB */
/*
* Find a mergeable slab cache
*/
int slab_unmergeable(struct kmem_cache *s)
{
if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE))
return 1;
if (!is_root_cache(s))
return 1;
if (s->ctor)
return 1;
/*
* We may have set a slab to be unmergeable during bootstrap.
*/
if (s->refcount < 0)
return 1;
return 0;
}
struct kmem_cache *find_mergeable(size_t size, size_t align,
unsigned long flags, const char *name, void (*ctor)(void *))
{
struct kmem_cache *s;
if (slab_nomerge)
return NULL;
if (ctor)
return NULL;
size = ALIGN(size, sizeof(void *));
align = calculate_alignment(flags, align, size);
size = ALIGN(size, align);
flags = kmem_cache_flags(size, flags, name, NULL);
if (flags & SLAB_NEVER_MERGE)
return NULL;
list_for_each_entry_reverse(s, &slab_root_caches, root_caches_node) {
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;
if (IS_ENABLED(CONFIG_SLAB) && align &&
(align > s->align || s->align % align))
continue;
return s;
}
return NULL;
}
/*
* 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.
*/
unsigned long calculate_alignment(unsigned long flags,
unsigned long align, unsigned long size)
{
/*
* If the user wants hardware cache aligned objects then follow that
* suggestion if the object is sufficiently large.
*
* The hardware cache alignment cannot override the specified
* alignment though. If that is greater then use it.
*/
if (flags & SLAB_HWCACHE_ALIGN) {
unsigned long ralign = cache_line_size();
while (size <= ralign / 2)
ralign /= 2;
align = max(align, ralign);
}
if (align < ARCH_SLAB_MINALIGN)
align = ARCH_SLAB_MINALIGN;
return ALIGN(align, sizeof(void *));
}
static struct kmem_cache *create_cache(const char *name,
size_t object_size, size_t size, size_t align,
unsigned long flags, void (*ctor)(void *),
struct mem_cgroup *memcg, struct kmem_cache *root_cache)
{
struct kmem_cache *s;
int err;
err = -ENOMEM;
s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
if (!s)
goto out;
s->name = name;
s->object_size = object_size;
s->size = size;
s->align = align;
s->ctor = ctor;
err = init_memcg_params(s, memcg, root_cache);
if (err)
goto out_free_cache;
err = __kmem_cache_create(s, flags);
if (err)
goto out_free_cache;
s->refcount = 1;
list_add(&s->list, &slab_caches);
memcg_link_cache(s);
out:
if (err)
return ERR_PTR(err);
return s;
out_free_cache:
destroy_memcg_params(s);
kmem_cache_free(kmem_cache, s);
goto out;
}
/*
* kmem_cache_create - Create a cache.
* @name: A string which is used in /proc/slabinfo to identify this cache.
* @size: The size of objects to be created in this cache.
* @align: The required alignment for the objects.
* @flags: SLAB flags
* @ctor: A constructor for the objects.
*
* Returns a ptr to the cache on success, NULL on failure.
* Cannot be called within a interrupt, 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.
*/
struct kmem_cache *
kmem_cache_create(const char *name, size_t size, size_t align,
unsigned long flags, void (*ctor)(void *))
{
struct kmem_cache *s = NULL;
const char *cache_name;
int err;
get_online_cpus();
get_online_mems();
memcg_get_cache_ids();
mutex_lock(&slab_mutex);
err = kmem_cache_sanity_check(name, 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;
s = __kmem_cache_alias(name, size, align, flags, ctor);
if (s)
goto out_unlock;
cache_name = kstrdup_const(name, GFP_KERNEL);
if (!cache_name) {
err = -ENOMEM;
goto out_unlock;
}
s = create_cache(cache_name, size, size,
calculate_alignment(flags, align, size),
flags, ctor, NULL, NULL);
if (IS_ERR(s)) {
err = PTR_ERR(s);
kfree_const(cache_name);
}
out_unlock:
mutex_unlock(&slab_mutex);
memcg_put_cache_ids();
put_online_mems();
put_online_cpus();
if (err) {
if (flags & SLAB_PANIC)
panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
name, err);
else {
pr_warn("kmem_cache_create(%s) failed with error %d\n",
name, err);
dump_stack();
}
return NULL;
}
return s;
}
EXPORT_SYMBOL(kmem_cache_create);
static void slab_caches_to_rcu_destroy_workfn(struct work_struct *work)
{
LIST_HEAD(to_destroy);
struct kmem_cache *s, *s2;
/*
* On destruction, SLAB_TYPESAFE_BY_RCU kmem_caches are put on the
* @slab_caches_to_rcu_destroy list. The slab pages are freed
* through RCU and and the associated kmem_cache are dereferenced
* while freeing the pages, so the kmem_caches should be freed only
* after the pending RCU operations are finished. As rcu_barrier()
* is a pretty slow operation, we batch all pending destructions
* asynchronously.
*/
mutex_lock(&slab_mutex);
list_splice_init(&slab_caches_to_rcu_destroy, &to_destroy);
mutex_unlock(&slab_mutex);
if (list_empty(&to_destroy))
return;
rcu_barrier();
list_for_each_entry_safe(s, s2, &to_destroy, list) {
#ifdef SLAB_SUPPORTS_SYSFS
sysfs_slab_release(s);
#else
slab_kmem_cache_release(s);
#endif
}
}
static int shutdown_cache(struct kmem_cache *s)
{
/* free asan quarantined objects */
kasan_cache_shutdown(s);
if (__kmem_cache_shutdown(s) != 0)
return -EBUSY;
memcg_unlink_cache(s);
list_del(&s->list);
if (s->flags & SLAB_TYPESAFE_BY_RCU) {
list_add_tail(&s->list, &slab_caches_to_rcu_destroy);
schedule_work(&slab_caches_to_rcu_destroy_work);
} else {
#ifdef SLAB_SUPPORTS_SYSFS
sysfs_slab_release(s);
#else
slab_kmem_cache_release(s);
#endif
}
return 0;
}
#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
/*
* memcg_create_kmem_cache - Create a cache for a memory cgroup.
* @memcg: The memory cgroup the new cache is for.
* @root_cache: The parent of the new cache.
*
* This function attempts to create a kmem cache that will serve allocation
* requests going from @memcg to @root_cache. The new cache inherits properties
* from its parent.
*/
void memcg_create_kmem_cache(struct mem_cgroup *memcg,
struct kmem_cache *root_cache)
{
static char memcg_name_buf[NAME_MAX + 1]; /* protected by slab_mutex */
struct cgroup_subsys_state *css = &memcg->css;
struct memcg_cache_array *arr;
struct kmem_cache *s = NULL;
char *cache_name;
int idx;
get_online_cpus();
get_online_mems();
mutex_lock(&slab_mutex);
/*
* The memory cgroup could have been offlined while the cache
* creation work was pending.
*/
if (memcg->kmem_state != KMEM_ONLINE)
goto out_unlock;
idx = memcg_cache_id(memcg);
arr = rcu_dereference_protected(root_cache->memcg_params.memcg_caches,
lockdep_is_held(&slab_mutex));
/*
* Since per-memcg caches are created asynchronously on first
* allocation (see memcg_kmem_get_cache()), several threads can try to
* create the same cache, but only one of them may succeed.
*/
if (arr->entries[idx])
goto out_unlock;
cgroup_name(css->cgroup, memcg_name_buf, sizeof(memcg_name_buf));
cache_name = kasprintf(GFP_KERNEL, "%s(%llu:%s)", root_cache->name,
css->serial_nr, memcg_name_buf);
if (!cache_name)
goto out_unlock;
s = create_cache(cache_name, root_cache->object_size,
root_cache->size, root_cache->align,
root_cache->flags & CACHE_CREATE_MASK,
root_cache->ctor, memcg, root_cache);
/*
* If we could not create a memcg cache, do not complain, because
* that's not critical at all as we can always proceed with the root
* cache.
*/
if (IS_ERR(s)) {
kfree(cache_name);
goto out_unlock;
}
/*
* Since readers won't lock (see cache_from_memcg_idx()), we need a
* barrier here to ensure nobody will see the kmem_cache partially
* initialized.
*/
smp_wmb();
arr->entries[idx] = s;
out_unlock:
mutex_unlock(&slab_mutex);
put_online_mems();
put_online_cpus();
}
static void kmemcg_deactivate_workfn(struct work_struct *work)
{
struct kmem_cache *s = container_of(work, struct kmem_cache,
memcg_params.deact_work);
get_online_cpus();
get_online_mems();
mutex_lock(&slab_mutex);
s->memcg_params.deact_fn(s);
mutex_unlock(&slab_mutex);
put_online_mems();
put_online_cpus();
/* done, put the ref from slab_deactivate_memcg_cache_rcu_sched() */
css_put(&s->memcg_params.memcg->css);
}
static void kmemcg_deactivate_rcufn(struct rcu_head *head)
{
struct kmem_cache *s = container_of(head, struct kmem_cache,
memcg_params.deact_rcu_head);
/*
* We need to grab blocking locks. Bounce to ->deact_work. The
* work item shares the space with the RCU head and can't be
* initialized eariler.
*/
INIT_WORK(&s->memcg_params.deact_work, kmemcg_deactivate_workfn);
queue_work(memcg_kmem_cache_wq, &s->memcg_params.deact_work);
}
/**
* slab_deactivate_memcg_cache_rcu_sched - schedule deactivation after a
* sched RCU grace period
* @s: target kmem_cache
* @deact_fn: deactivation function to call
*
* Schedule @deact_fn to be invoked with online cpus, mems and slab_mutex
* held after a sched RCU grace period. The slab is guaranteed to stay
* alive until @deact_fn is finished. This is to be used from
* __kmemcg_cache_deactivate().
*/
void slab_deactivate_memcg_cache_rcu_sched(struct kmem_cache *s,
void (*deact_fn)(struct kmem_cache *))
{
if (WARN_ON_ONCE(is_root_cache(s)) ||
WARN_ON_ONCE(s->memcg_params.deact_fn))
return;
/* pin memcg so that @s doesn't get destroyed in the middle */
css_get(&s->memcg_params.memcg->css);
s->memcg_params.deact_fn = deact_fn;
call_rcu_sched(&s->memcg_params.deact_rcu_head, kmemcg_deactivate_rcufn);
}
void memcg_deactivate_kmem_caches(struct mem_cgroup *memcg)
{
int idx;
struct memcg_cache_array *arr;
struct kmem_cache *s, *c;
idx = memcg_cache_id(memcg);
get_online_cpus();
get_online_mems();
mutex_lock(&slab_mutex);
list_for_each_entry(s, &slab_root_caches, root_caches_node) {
arr = rcu_dereference_protected(s->memcg_params.memcg_caches,
lockdep_is_held(&slab_mutex));
c = arr->entries[idx];
if (!c)
continue;
__kmemcg_cache_deactivate(c);
arr->entries[idx] = NULL;
}
mutex_unlock(&slab_mutex);
put_online_mems();
put_online_cpus();
}
void memcg_destroy_kmem_caches(struct mem_cgroup *memcg)
{
struct kmem_cache *s, *s2;
get_online_cpus();
get_online_mems();
mutex_lock(&slab_mutex);
list_for_each_entry_safe(s, s2, &memcg->kmem_caches,
memcg_params.kmem_caches_node) {
/*
* The cgroup is about to be freed and therefore has no charges
* left. Hence, all its caches must be empty by now.
*/
BUG_ON(shutdown_cache(s));
}
mutex_unlock(&slab_mutex);
put_online_mems();
put_online_cpus();
}
static int shutdown_memcg_caches(struct kmem_cache *s)
{
struct memcg_cache_array *arr;
struct kmem_cache *c, *c2;
LIST_HEAD(busy);
int i;
BUG_ON(!is_root_cache(s));
/*
* First, shutdown active caches, i.e. caches that belong to online
* memory cgroups.
*/
arr = rcu_dereference_protected(s->memcg_params.memcg_caches,
lockdep_is_held(&slab_mutex));
for_each_memcg_cache_index(i) {
c = arr->entries[i];
if (!c)
continue;
if (shutdown_cache(c))
/*
* The cache still has objects. Move it to a temporary
* list so as not to try to destroy it for a second
* time while iterating over inactive caches below.
*/
list_move(&c->memcg_params.children_node, &busy);
else
/*
* The cache is empty and will be destroyed soon. Clear
* the pointer to it in the memcg_caches array so that
* it will never be accessed even if the root cache
* stays alive.
*/
arr->entries[i] = NULL;
}
/*
* Second, shutdown all caches left from memory cgroups that are now
* offline.
*/
list_for_each_entry_safe(c, c2, &s->memcg_params.children,
memcg_params.children_node)
shutdown_cache(c);
list_splice(&busy, &s->memcg_params.children);
/*
* A cache being destroyed must be empty. In particular, this means
* that all per memcg caches attached to it must be empty too.
*/
if (!list_empty(&s->memcg_params.children))
return -EBUSY;
return 0;
}
#else
static inline int shutdown_memcg_caches(struct kmem_cache *s)
{
return 0;
}
#endif /* CONFIG_MEMCG && !CONFIG_SLOB */
void slab_kmem_cache_release(struct kmem_cache *s)
{
__kmem_cache_release(s);
destroy_memcg_params(s);
kfree_const(s->name);
kmem_cache_free(kmem_cache, s);
}
void kmem_cache_destroy(struct kmem_cache *s)
{
int err;
if (unlikely(!s))
return;
get_online_cpus();
get_online_mems();
mutex_lock(&slab_mutex);
s->refcount--;
if (s->refcount)
goto out_unlock;
err = shutdown_memcg_caches(s);
if (!err)
err = shutdown_cache(s);
if (err) {
pr_err("kmem_cache_destroy %s: Slab cache still has objects\n",
s->name);
dump_stack();
}
out_unlock:
mutex_unlock(&slab_mutex);
put_online_mems();
put_online_cpus();
}
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.
*/
int kmem_cache_shrink(struct kmem_cache *cachep)
{
int ret;
get_online_cpus();
get_online_mems();
kasan_cache_shrink(cachep);
ret = __kmem_cache_shrink(cachep);
put_online_mems();
put_online_cpus();
return ret;
}
EXPORT_SYMBOL(kmem_cache_shrink);
bool slab_is_available(void)
{
return slab_state >= UP;
}
#ifndef CONFIG_SLOB
/* Create a cache during boot when no slab services are available yet */
void __init create_boot_cache(struct kmem_cache *s, const char *name, size_t size,
unsigned long flags)
{
int err;
s->name = name;
s->size = s->object_size = size;
s->align = calculate_alignment(flags, ARCH_KMALLOC_MINALIGN, size);
slab_init_memcg_params(s);
err = __kmem_cache_create(s, flags);
if (err)
panic("Creation of kmalloc slab %s size=%zu failed. Reason %d\n",
name, size, err);
s->refcount = -1; /* Exempt from merging for now */
}
struct kmem_cache *__init create_kmalloc_cache(const char *name, size_t size,
unsigned long 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);
list_add(&s->list, &slab_caches);
memcg_link_cache(s);
s->refcount = 1;
return s;
}
struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
EXPORT_SYMBOL(kmalloc_caches);
#ifdef CONFIG_ZONE_DMA
struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
EXPORT_SYMBOL(kmalloc_dma_caches);
#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.
*/
static s8 size_index[24] = {
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 */
};
static inline int size_index_elem(size_t bytes)
{
return (bytes - 1) / 8;
}
/*
* Find the kmem_cache structure that serves a given size of
* allocation
*/
struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
{
int index;
if (unlikely(size > KMALLOC_MAX_SIZE)) {
WARN_ON_ONCE(!(flags & __GFP_NOWARN));
return NULL;
}
if (size <= 192) {
if (!size)
return ZERO_SIZE_PTR;
index = size_index[size_index_elem(size)];
} else
index = fls(size - 1);
#ifdef CONFIG_ZONE_DMA
if (unlikely((flags & GFP_DMA)))
return kmalloc_dma_caches[index];
#endif
return kmalloc_caches[index];
}
/*
* kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time.
* kmalloc_index() supports up to 2^26=64MB, so the final entry of the table is
* kmalloc-67108864.
*/
const struct kmalloc_info_struct kmalloc_info[] __initconst = {
{NULL, 0}, {"kmalloc-96", 96},
{"kmalloc-192", 192}, {"kmalloc-8", 8},
{"kmalloc-16", 16}, {"kmalloc-32", 32},
{"kmalloc-64", 64}, {"kmalloc-128", 128},
{"kmalloc-256", 256}, {"kmalloc-512", 512},
{"kmalloc-1024", 1024}, {"kmalloc-2048", 2048},
{"kmalloc-4096", 4096}, {"kmalloc-8192", 8192},
{"kmalloc-16384", 16384}, {"kmalloc-32768", 32768},
{"kmalloc-65536", 65536}, {"kmalloc-131072", 131072},
{"kmalloc-262144", 262144}, {"kmalloc-524288", 524288},
{"kmalloc-1048576", 1048576}, {"kmalloc-2097152", 2097152},
{"kmalloc-4194304", 4194304}, {"kmalloc-8388608", 8388608},
{"kmalloc-16777216", 16777216}, {"kmalloc-33554432", 33554432},
{"kmalloc-67108864", 67108864}
};
/*
* 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)
{
int i;
BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
(KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
int elem = size_index_elem(i);
if (elem >= ARRAY_SIZE(size_index))
break;
size_index[elem] = KMALLOC_SHIFT_LOW;
}
if (KMALLOC_MIN_SIZE >= 64) {
/*
* The 96 byte size cache is not used if the alignment
* is 64 byte.
*/
for (i = 64 + 8; i <= 96; i += 8)
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)
size_index[size_index_elem(i)] = 8;
}
}
static void __init new_kmalloc_cache(int idx, unsigned long flags)
{
kmalloc_caches[idx] = create_kmalloc_cache(kmalloc_info[idx].name,
kmalloc_info[idx].size, flags);
}
/*
* 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(unsigned long flags)
{
int i;
for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
if (!kmalloc_caches[i])
new_kmalloc_cache(i, flags);
/*
* Caches that are not of the two-to-the-power-of size.
* These have to be created immediately after the
* earlier power of two caches
*/
if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1] && i == 6)
new_kmalloc_cache(1, flags);
if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2] && i == 7)
new_kmalloc_cache(2, flags);
}
/* Kmalloc array is now usable */
slab_state = UP;
#ifdef CONFIG_ZONE_DMA
for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
struct kmem_cache *s = kmalloc_caches[i];
if (s) {
int size = kmalloc_size(i);
char *n = kasprintf(GFP_NOWAIT,
"dma-kmalloc-%d", size);
BUG_ON(!n);
kmalloc_dma_caches[i] = create_kmalloc_cache(n,
size, SLAB_CACHE_DMA | flags);
}
}
#endif
}
#endif /* !CONFIG_SLOB */
/*
* To avoid unnecessary overhead, we pass through large allocation requests
* directly to the page allocator. We use __GFP_COMP, because we will need to
* know the allocation order to free the pages properly in kfree.
*/
void *kmalloc_order(size_t size, gfp_t flags, unsigned int order)
{
void *ret;
struct page *page;
flags |= __GFP_COMP;
page = alloc_pages(flags, order);
ret = page ? page_address(page) : NULL;
kmemleak_alloc(ret, size, 1, flags);
kasan_kmalloc_large(ret, size, flags);
return ret;
}
EXPORT_SYMBOL(kmalloc_order);
#ifdef CONFIG_TRACING
void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
{
void *ret = kmalloc_order(size, flags, order);
trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags);
return ret;
}
EXPORT_SYMBOL(kmalloc_order_trace);
#endif
#ifdef CONFIG_SLAB_FREELIST_RANDOM
/* Randomize a generic freelist */
static void freelist_randomize(struct rnd_state *state, unsigned int *list,
size_t count)
{
size_t i;
unsigned int rand;
for (i = 0; i < count; i++)
list[i] = i;
/* Fisher-Yates shuffle */
for (i = count - 1; i > 0; i--) {
rand = prandom_u32_state(state);
rand %= (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)
{
struct rnd_state state;
if (count < 2 || cachep->random_seq)
return 0;
cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp);
if (!cachep->random_seq)
return -ENOMEM;
/* Get best entropy at this stage of boot */
prandom_seed_state(&state, get_random_long());
freelist_randomize(&state, 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_SLABINFO
#ifdef CONFIG_SLAB
#define SLABINFO_RIGHTS (S_IWUSR | S_IRUSR)
#else
#define SLABINFO_RIGHTS S_IRUSR
#endif
static void print_slabinfo_header(struct seq_file *m)
{
/*
* Output format version, so at least we can change it
* without _too_ many complaints.
*/
#ifdef CONFIG_DEBUG_SLAB
seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
#else
seq_puts(m, "slabinfo - version: 2.1\n");
#endif
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>");
#ifdef CONFIG_DEBUG_SLAB
seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> <error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
#endif
seq_putc(m, '\n');
}
void *slab_start(struct seq_file *m, loff_t *pos)
{
mutex_lock(&slab_mutex);
return seq_list_start(&slab_root_caches, *pos);
}
void *slab_next(struct seq_file *m, void *p, loff_t *pos)
{
return seq_list_next(p, &slab_root_caches, pos);
}
void slab_stop(struct seq_file *m, void *p)
{
mutex_unlock(&slab_mutex);
}
static void
memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info)
{
struct kmem_cache *c;
struct slabinfo sinfo;
if (!is_root_cache(s))
return;
for_each_memcg_cache(c, s) {
memset(&sinfo, 0, sizeof(sinfo));
get_slabinfo(c, &sinfo);
info->active_slabs += sinfo.active_slabs;
info->num_slabs += sinfo.num_slabs;
info->shared_avail += sinfo.shared_avail;
info->active_objs += sinfo.active_objs;
info->num_objs += sinfo.num_objs;
}
}
static void cache_show(struct kmem_cache *s, struct seq_file *m)
{
struct slabinfo sinfo;
memset(&sinfo, 0, sizeof(sinfo));
get_slabinfo(s, &sinfo);
memcg_accumulate_slabinfo(s, &sinfo);
seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
cache_name(s), 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);
slabinfo_show_stats(m, s);
seq_putc(m, '\n');
}
static int slab_show(struct seq_file *m, void *p)
{
struct kmem_cache *s = list_entry(p, struct kmem_cache, root_caches_node);
if (p == slab_root_caches.next)
print_slabinfo_header(m);
cache_show(s, m);
return 0;
}
#if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
void *memcg_slab_start(struct seq_file *m, loff_t *pos)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
mutex_lock(&slab_mutex);
return seq_list_start(&memcg->kmem_caches, *pos);
}
void *memcg_slab_next(struct seq_file *m, void *p, loff_t *pos)
{
struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
return seq_list_next(p, &memcg->kmem_caches, pos);
}
void memcg_slab_stop(struct seq_file *m, void *p)
{
mutex_unlock(&slab_mutex);
}
int memcg_slab_show(struct seq_file *m, void *p)
{
struct kmem_cache *s = list_entry(p, struct kmem_cache,
memcg_params.kmem_caches_node);
struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
if (p == memcg->kmem_caches.next)
print_slabinfo_header(m);
cache_show(s, m);
return 0;
}
#endif
/*
* 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 file_operations proc_slabinfo_operations = {
.open = slabinfo_open,
.read = seq_read,
.write = slabinfo_write,
.llseek = seq_lseek,
.release = seq_release,
};
static int __init slab_proc_init(void)
{
proc_create("slabinfo", SLABINFO_RIGHTS, NULL,
&proc_slabinfo_operations);
return 0;
}
module_init(slab_proc_init);
#endif /* CONFIG_SLABINFO */
static __always_inline void *__do_krealloc(const void *p, size_t new_size,
gfp_t flags)
{
void *ret;
size_t ks = 0;
if (p)
ks = ksize(p);
if (ks >= new_size) {
kasan_krealloc((void *)p, new_size, flags);
return (void *)p;
}
ret = kmalloc_track_caller(new_size, flags);
if (ret && p)
memcpy(ret, p, ks);
return ret;
}
/**
* __krealloc - like krealloc() but don't free @p.
* @p: object to reallocate memory for.
* @new_size: how many bytes of memory are required.
* @flags: the type of memory to allocate.
*
* This function is like krealloc() except it never frees the originally
* allocated buffer. Use this if you don't want to free the buffer immediately
* like, for example, with RCU.
*/
void *__krealloc(const void *p, size_t new_size, gfp_t flags)
{
if (unlikely(!new_size))
return ZERO_SIZE_PTR;
return __do_krealloc(p, new_size, flags);
}
EXPORT_SYMBOL(__krealloc);
/**
* krealloc - reallocate memory. The contents will remain unchanged.
* @p: object to reallocate memory for.
* @new_size: how many bytes of memory are required.
* @flags: the type of memory to allocate.
*
* The contents of the object pointed to are preserved up to the
* lesser of the new and old sizes. If @p is %NULL, krealloc()
* behaves exactly like kmalloc(). If @new_size is 0 and @p is not a
* %NULL pointer, the object pointed to is freed.
*/
void *krealloc(const void *p, size_t new_size, gfp_t flags)
{
void *ret;
if (unlikely(!new_size)) {
kfree(p);
return ZERO_SIZE_PTR;
}
ret = __do_krealloc(p, new_size, flags);
if (ret && p != ret)
kfree(p);
return ret;
}
EXPORT_SYMBOL(krealloc);
/**
* kzfree - like kfree but zero memory
* @p: object to free memory of
*
* The memory of the object @p points to is zeroed before freed.
* If @p is %NULL, kzfree() 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 kzfree(const void *p)
{
size_t ks;
void *mem = (void *)p;
if (unlikely(ZERO_OR_NULL_PTR(mem)))
return;
ks = ksize(mem);
memset(mem, 0, ks);
kfree(mem);
}
EXPORT_SYMBOL(kzfree);
/* Tracepoints definitions. */
EXPORT_TRACEPOINT_SYMBOL(kmalloc);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
EXPORT_TRACEPOINT_SYMBOL(kmalloc_node);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node);
EXPORT_TRACEPOINT_SYMBOL(kfree);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);