linux/mm/slab.h
Alexander Potapenko 6471384af2 mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options
Patch series "add init_on_alloc/init_on_free boot options", v10.

Provide init_on_alloc and init_on_free boot options.

These are aimed at preventing possible information leaks and making the
control-flow bugs that depend on uninitialized values more deterministic.

Enabling either of the options guarantees that the memory returned by the
page allocator and SL[AU]B is initialized with zeroes.  SLOB allocator
isn't supported at the moment, as its emulation of kmem caches complicates
handling of SLAB_TYPESAFE_BY_RCU caches correctly.

Enabling init_on_free also guarantees that pages and heap objects are
initialized right after they're freed, so it won't be possible to access
stale data by using a dangling pointer.

As suggested by Michal Hocko, right now we don't let the heap users to
disable initialization for certain allocations.  There's not enough
evidence that doing so can speed up real-life cases, and introducing ways
to opt-out may result in things going out of control.

This patch (of 2):

The new options are needed to prevent possible information leaks and make
control-flow bugs that depend on uninitialized values more deterministic.

This is expected to be on-by-default on Android and Chrome OS.  And it
gives the opportunity for anyone else to use it under distros too via the
boot args.  (The init_on_free feature is regularly requested by folks
where memory forensics is included in their threat models.)

init_on_alloc=1 makes the kernel initialize newly allocated pages and heap
objects with zeroes.  Initialization is done at allocation time at the
places where checks for __GFP_ZERO are performed.

init_on_free=1 makes the kernel initialize freed pages and heap objects
with zeroes upon their deletion.  This helps to ensure sensitive data
doesn't leak via use-after-free accesses.

Both init_on_alloc=1 and init_on_free=1 guarantee that the allocator
returns zeroed memory.  The two exceptions are slab caches with
constructors and SLAB_TYPESAFE_BY_RCU flag.  Those are never
zero-initialized to preserve their semantics.

Both init_on_alloc and init_on_free default to zero, but those defaults
can be overridden with CONFIG_INIT_ON_ALLOC_DEFAULT_ON and
CONFIG_INIT_ON_FREE_DEFAULT_ON.

If either SLUB poisoning or page poisoning is enabled, those options take
precedence over init_on_alloc and init_on_free: initialization is only
applied to unpoisoned allocations.

Slowdown for the new features compared to init_on_free=0, init_on_alloc=0:

hackbench, init_on_free=1:  +7.62% sys time (st.err 0.74%)
hackbench, init_on_alloc=1: +7.75% sys time (st.err 2.14%)

Linux build with -j12, init_on_free=1:  +8.38% wall time (st.err 0.39%)
Linux build with -j12, init_on_free=1:  +24.42% sys time (st.err 0.52%)
Linux build with -j12, init_on_alloc=1: -0.13% wall time (st.err 0.42%)
Linux build with -j12, init_on_alloc=1: +0.57% sys time (st.err 0.40%)

The slowdown for init_on_free=0, init_on_alloc=0 compared to the baseline
is within the standard error.

The new features are also going to pave the way for hardware memory
tagging (e.g.  arm64's MTE), which will require both on_alloc and on_free
hooks to set the tags for heap objects.  With MTE, tagging will have the
same cost as memory initialization.

Although init_on_free is rather costly, there are paranoid use-cases where
in-memory data lifetime is desired to be minimized.  There are various
arguments for/against the realism of the associated threat models, but
given that we'll need the infrastructure for MTE anyway, and there are
people who want wipe-on-free behavior no matter what the performance cost,
it seems reasonable to include it in this series.

[glider@google.com: v8]
  Link: http://lkml.kernel.org/r/20190626121943.131390-2-glider@google.com
[glider@google.com: v9]
  Link: http://lkml.kernel.org/r/20190627130316.254309-2-glider@google.com
[glider@google.com: v10]
  Link: http://lkml.kernel.org/r/20190628093131.199499-2-glider@google.com
Link: http://lkml.kernel.org/r/20190617151050.92663-2-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Michal Hocko <mhocko@suse.cz>		[page and dmapool parts
Acked-by: James Morris <jamorris@linux.microsoft.com>]
Cc: Christoph Lameter <cl@linux.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Kostya Serebryany <kcc@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Sandeep Patil <sspatil@android.com>
Cc: Laura Abbott <labbott@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Jann Horn <jannh@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Marco Elver <elver@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2019-07-12 11:05:46 -07:00

631 lines
17 KiB
C

/* SPDX-License-Identifier: GPL-2.0 */
#ifndef MM_SLAB_H
#define MM_SLAB_H
/*
* Internal slab definitions
*/
#ifdef CONFIG_SLOB
/*
* Common fields provided in kmem_cache by all slab allocators
* This struct is either used directly by the allocator (SLOB)
* or the allocator must include definitions for all fields
* provided in kmem_cache_common in their definition of kmem_cache.
*
* Once we can do anonymous structs (C11 standard) we could put a
* anonymous struct definition in these allocators so that the
* separate allocations in the kmem_cache structure of SLAB and
* SLUB is no longer needed.
*/
struct kmem_cache {
unsigned int object_size;/* The original size of the object */
unsigned int size; /* The aligned/padded/added on size */
unsigned int align; /* Alignment as calculated */
slab_flags_t flags; /* Active flags on the slab */
unsigned int useroffset;/* Usercopy region offset */
unsigned int usersize; /* Usercopy region size */
const char *name; /* Slab name for sysfs */
int refcount; /* Use counter */
void (*ctor)(void *); /* Called on object slot creation */
struct list_head list; /* List of all slab caches on the system */
};
#endif /* CONFIG_SLOB */
#ifdef CONFIG_SLAB
#include <linux/slab_def.h>
#endif
#ifdef CONFIG_SLUB
#include <linux/slub_def.h>
#endif
#include <linux/memcontrol.h>
#include <linux/fault-inject.h>
#include <linux/kasan.h>
#include <linux/kmemleak.h>
#include <linux/random.h>
#include <linux/sched/mm.h>
/*
* State of the slab allocator.
*
* This is used to describe the states of the allocator during bootup.
* Allocators use this to gradually bootstrap themselves. Most allocators
* have the problem that the structures used for managing slab caches are
* allocated from slab caches themselves.
*/
enum slab_state {
DOWN, /* No slab functionality yet */
PARTIAL, /* SLUB: kmem_cache_node available */
PARTIAL_NODE, /* SLAB: kmalloc size for node struct available */
UP, /* Slab caches usable but not all extras yet */
FULL /* Everything is working */
};
extern enum slab_state slab_state;
/* The slab cache mutex protects the management structures during changes */
extern struct mutex slab_mutex;
/* The list of all slab caches on the system */
extern struct list_head slab_caches;
/* The slab cache that manages slab cache information */
extern struct kmem_cache *kmem_cache;
/* A table of kmalloc cache names and sizes */
extern const struct kmalloc_info_struct {
const char *name;
unsigned int size;
} kmalloc_info[];
#ifndef CONFIG_SLOB
/* Kmalloc array related functions */
void setup_kmalloc_cache_index_table(void);
void create_kmalloc_caches(slab_flags_t);
/* Find the kmalloc slab corresponding for a certain size */
struct kmem_cache *kmalloc_slab(size_t, gfp_t);
#endif
/* Functions provided by the slab allocators */
int __kmem_cache_create(struct kmem_cache *, slab_flags_t flags);
struct kmem_cache *create_kmalloc_cache(const char *name, unsigned int size,
slab_flags_t flags, unsigned int useroffset,
unsigned int usersize);
extern void create_boot_cache(struct kmem_cache *, const char *name,
unsigned int size, slab_flags_t flags,
unsigned int useroffset, unsigned int usersize);
int slab_unmergeable(struct kmem_cache *s);
struct kmem_cache *find_mergeable(unsigned size, unsigned align,
slab_flags_t flags, const char *name, void (*ctor)(void *));
#ifndef CONFIG_SLOB
struct kmem_cache *
__kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
slab_flags_t flags, void (*ctor)(void *));
slab_flags_t kmem_cache_flags(unsigned int object_size,
slab_flags_t flags, const char *name,
void (*ctor)(void *));
#else
static inline struct kmem_cache *
__kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
slab_flags_t flags, void (*ctor)(void *))
{ return NULL; }
static inline slab_flags_t kmem_cache_flags(unsigned int object_size,
slab_flags_t flags, const char *name,
void (*ctor)(void *))
{
return flags;
}
#endif
/* Legal flag mask for kmem_cache_create(), for various configurations */
#define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA | \
SLAB_CACHE_DMA32 | SLAB_PANIC | \
SLAB_TYPESAFE_BY_RCU | SLAB_DEBUG_OBJECTS )
#if defined(CONFIG_DEBUG_SLAB)
#define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)
#elif defined(CONFIG_SLUB_DEBUG)
#define SLAB_DEBUG_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
SLAB_TRACE | SLAB_CONSISTENCY_CHECKS)
#else
#define SLAB_DEBUG_FLAGS (0)
#endif
#if defined(CONFIG_SLAB)
#define SLAB_CACHE_FLAGS (SLAB_MEM_SPREAD | SLAB_NOLEAKTRACE | \
SLAB_RECLAIM_ACCOUNT | SLAB_TEMPORARY | \
SLAB_ACCOUNT)
#elif defined(CONFIG_SLUB)
#define SLAB_CACHE_FLAGS (SLAB_NOLEAKTRACE | SLAB_RECLAIM_ACCOUNT | \
SLAB_TEMPORARY | SLAB_ACCOUNT)
#else
#define SLAB_CACHE_FLAGS (0)
#endif
/* Common flags available with current configuration */
#define CACHE_CREATE_MASK (SLAB_CORE_FLAGS | SLAB_DEBUG_FLAGS | SLAB_CACHE_FLAGS)
/* Common flags permitted for kmem_cache_create */
#define SLAB_FLAGS_PERMITTED (SLAB_CORE_FLAGS | \
SLAB_RED_ZONE | \
SLAB_POISON | \
SLAB_STORE_USER | \
SLAB_TRACE | \
SLAB_CONSISTENCY_CHECKS | \
SLAB_MEM_SPREAD | \
SLAB_NOLEAKTRACE | \
SLAB_RECLAIM_ACCOUNT | \
SLAB_TEMPORARY | \
SLAB_ACCOUNT)
bool __kmem_cache_empty(struct kmem_cache *);
int __kmem_cache_shutdown(struct kmem_cache *);
void __kmem_cache_release(struct kmem_cache *);
int __kmem_cache_shrink(struct kmem_cache *);
void __kmemcg_cache_deactivate(struct kmem_cache *s);
void __kmemcg_cache_deactivate_after_rcu(struct kmem_cache *s);
void slab_kmem_cache_release(struct kmem_cache *);
struct seq_file;
struct file;
struct slabinfo {
unsigned long active_objs;
unsigned long num_objs;
unsigned long active_slabs;
unsigned long num_slabs;
unsigned long shared_avail;
unsigned int limit;
unsigned int batchcount;
unsigned int shared;
unsigned int objects_per_slab;
unsigned int cache_order;
};
void get_slabinfo(struct kmem_cache *s, struct slabinfo *sinfo);
void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s);
ssize_t slabinfo_write(struct file *file, const char __user *buffer,
size_t count, loff_t *ppos);
/*
* Generic implementation of bulk operations
* These are useful for situations in which the allocator cannot
* perform optimizations. In that case segments of the object listed
* may be allocated or freed using these operations.
*/
void __kmem_cache_free_bulk(struct kmem_cache *, size_t, void **);
int __kmem_cache_alloc_bulk(struct kmem_cache *, gfp_t, size_t, void **);
static inline int cache_vmstat_idx(struct kmem_cache *s)
{
return (s->flags & SLAB_RECLAIM_ACCOUNT) ?
NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE;
}
#ifdef CONFIG_MEMCG_KMEM
/* List of all root caches. */
extern struct list_head slab_root_caches;
#define root_caches_node memcg_params.__root_caches_node
/*
* Iterate over all memcg caches of the given root cache. The caller must hold
* slab_mutex.
*/
#define for_each_memcg_cache(iter, root) \
list_for_each_entry(iter, &(root)->memcg_params.children, \
memcg_params.children_node)
static inline bool is_root_cache(struct kmem_cache *s)
{
return !s->memcg_params.root_cache;
}
static inline bool slab_equal_or_root(struct kmem_cache *s,
struct kmem_cache *p)
{
return p == s || p == s->memcg_params.root_cache;
}
/*
* We use suffixes to the name in memcg because we can't have caches
* created in the system with the same name. But when we print them
* locally, better refer to them with the base name
*/
static inline const char *cache_name(struct kmem_cache *s)
{
if (!is_root_cache(s))
s = s->memcg_params.root_cache;
return s->name;
}
static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s)
{
if (is_root_cache(s))
return s;
return s->memcg_params.root_cache;
}
/*
* Expects a pointer to a slab page. Please note, that PageSlab() check
* isn't sufficient, as it returns true also for tail compound slab pages,
* which do not have slab_cache pointer set.
* So this function assumes that the page can pass PageHead() and PageSlab()
* checks.
*
* The kmem_cache can be reparented asynchronously. The caller must ensure
* the memcg lifetime, e.g. by taking rcu_read_lock() or cgroup_mutex.
*/
static inline struct mem_cgroup *memcg_from_slab_page(struct page *page)
{
struct kmem_cache *s;
s = READ_ONCE(page->slab_cache);
if (s && !is_root_cache(s))
return READ_ONCE(s->memcg_params.memcg);
return NULL;
}
/*
* Charge the slab page belonging to the non-root kmem_cache.
* Can be called for non-root kmem_caches only.
*/
static __always_inline int memcg_charge_slab(struct page *page,
gfp_t gfp, int order,
struct kmem_cache *s)
{
struct mem_cgroup *memcg;
struct lruvec *lruvec;
int ret;
rcu_read_lock();
memcg = READ_ONCE(s->memcg_params.memcg);
while (memcg && !css_tryget_online(&memcg->css))
memcg = parent_mem_cgroup(memcg);
rcu_read_unlock();
if (unlikely(!memcg || mem_cgroup_is_root(memcg))) {
mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s),
(1 << order));
percpu_ref_get_many(&s->memcg_params.refcnt, 1 << order);
return 0;
}
ret = memcg_kmem_charge_memcg(page, gfp, order, memcg);
if (ret)
goto out;
lruvec = mem_cgroup_lruvec(page_pgdat(page), memcg);
mod_lruvec_state(lruvec, cache_vmstat_idx(s), 1 << order);
/* transer try_charge() page references to kmem_cache */
percpu_ref_get_many(&s->memcg_params.refcnt, 1 << order);
css_put_many(&memcg->css, 1 << order);
out:
css_put(&memcg->css);
return ret;
}
/*
* Uncharge a slab page belonging to a non-root kmem_cache.
* Can be called for non-root kmem_caches only.
*/
static __always_inline void memcg_uncharge_slab(struct page *page, int order,
struct kmem_cache *s)
{
struct mem_cgroup *memcg;
struct lruvec *lruvec;
rcu_read_lock();
memcg = READ_ONCE(s->memcg_params.memcg);
if (likely(!mem_cgroup_is_root(memcg))) {
lruvec = mem_cgroup_lruvec(page_pgdat(page), memcg);
mod_lruvec_state(lruvec, cache_vmstat_idx(s), -(1 << order));
memcg_kmem_uncharge_memcg(page, order, memcg);
} else {
mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s),
-(1 << order));
}
rcu_read_unlock();
percpu_ref_put_many(&s->memcg_params.refcnt, 1 << order);
}
extern void slab_init_memcg_params(struct kmem_cache *);
extern void memcg_link_cache(struct kmem_cache *s, struct mem_cgroup *memcg);
#else /* CONFIG_MEMCG_KMEM */
/* If !memcg, all caches are root. */
#define slab_root_caches slab_caches
#define root_caches_node list
#define for_each_memcg_cache(iter, root) \
for ((void)(iter), (void)(root); 0; )
static inline bool is_root_cache(struct kmem_cache *s)
{
return true;
}
static inline bool slab_equal_or_root(struct kmem_cache *s,
struct kmem_cache *p)
{
return s == p;
}
static inline const char *cache_name(struct kmem_cache *s)
{
return s->name;
}
static inline struct kmem_cache *memcg_root_cache(struct kmem_cache *s)
{
return s;
}
static inline struct mem_cgroup *memcg_from_slab_page(struct page *page)
{
return NULL;
}
static inline int memcg_charge_slab(struct page *page, gfp_t gfp, int order,
struct kmem_cache *s)
{
return 0;
}
static inline void memcg_uncharge_slab(struct page *page, int order,
struct kmem_cache *s)
{
}
static inline void slab_init_memcg_params(struct kmem_cache *s)
{
}
static inline void memcg_link_cache(struct kmem_cache *s,
struct mem_cgroup *memcg)
{
}
#endif /* CONFIG_MEMCG_KMEM */
static inline struct kmem_cache *virt_to_cache(const void *obj)
{
struct page *page;
page = virt_to_head_page(obj);
if (WARN_ONCE(!PageSlab(page), "%s: Object is not a Slab page!\n",
__func__))
return NULL;
return page->slab_cache;
}
static __always_inline int charge_slab_page(struct page *page,
gfp_t gfp, int order,
struct kmem_cache *s)
{
if (is_root_cache(s)) {
mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s),
1 << order);
return 0;
}
return memcg_charge_slab(page, gfp, order, s);
}
static __always_inline void uncharge_slab_page(struct page *page, int order,
struct kmem_cache *s)
{
if (is_root_cache(s)) {
mod_node_page_state(page_pgdat(page), cache_vmstat_idx(s),
-(1 << order));
return;
}
memcg_uncharge_slab(page, order, s);
}
static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)
{
struct kmem_cache *cachep;
/*
* When kmemcg is not being used, both assignments should return the
* same value. but we don't want to pay the assignment price in that
* case. If it is not compiled in, the compiler should be smart enough
* to not do even the assignment. In that case, slab_equal_or_root
* will also be a constant.
*/
if (!memcg_kmem_enabled() &&
!IS_ENABLED(CONFIG_SLAB_FREELIST_HARDENED) &&
!unlikely(s->flags & SLAB_CONSISTENCY_CHECKS))
return s;
cachep = virt_to_cache(x);
WARN_ONCE(cachep && !slab_equal_or_root(cachep, s),
"%s: Wrong slab cache. %s but object is from %s\n",
__func__, s->name, cachep->name);
return cachep;
}
static inline size_t slab_ksize(const struct kmem_cache *s)
{
#ifndef CONFIG_SLUB
return s->object_size;
#else /* CONFIG_SLUB */
# ifdef CONFIG_SLUB_DEBUG
/*
* Debugging requires use of the padding between object
* and whatever may come after it.
*/
if (s->flags & (SLAB_RED_ZONE | SLAB_POISON))
return s->object_size;
# endif
if (s->flags & SLAB_KASAN)
return s->object_size;
/*
* If we have the need to store the freelist pointer
* back there or track user information then we can
* only use the space before that information.
*/
if (s->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_STORE_USER))
return s->inuse;
/*
* Else we can use all the padding etc for the allocation
*/
return s->size;
#endif
}
static inline struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s,
gfp_t flags)
{
flags &= gfp_allowed_mask;
fs_reclaim_acquire(flags);
fs_reclaim_release(flags);
might_sleep_if(gfpflags_allow_blocking(flags));
if (should_failslab(s, flags))
return NULL;
if (memcg_kmem_enabled() &&
((flags & __GFP_ACCOUNT) || (s->flags & SLAB_ACCOUNT)))
return memcg_kmem_get_cache(s);
return s;
}
static inline void slab_post_alloc_hook(struct kmem_cache *s, gfp_t flags,
size_t size, void **p)
{
size_t i;
flags &= gfp_allowed_mask;
for (i = 0; i < size; i++) {
p[i] = kasan_slab_alloc(s, p[i], flags);
/* As p[i] might get tagged, call kmemleak hook after KASAN. */
kmemleak_alloc_recursive(p[i], s->object_size, 1,
s->flags, flags);
}
if (memcg_kmem_enabled())
memcg_kmem_put_cache(s);
}
#ifndef CONFIG_SLOB
/*
* The slab lists for all objects.
*/
struct kmem_cache_node {
spinlock_t list_lock;
#ifdef CONFIG_SLAB
struct list_head slabs_partial; /* partial list first, better asm code */
struct list_head slabs_full;
struct list_head slabs_free;
unsigned long total_slabs; /* length of all slab lists */
unsigned long free_slabs; /* length of free slab list only */
unsigned long free_objects;
unsigned int free_limit;
unsigned int colour_next; /* Per-node cache coloring */
struct array_cache *shared; /* shared per node */
struct alien_cache **alien; /* on other nodes */
unsigned long next_reap; /* updated without locking */
int free_touched; /* updated without locking */
#endif
#ifdef CONFIG_SLUB
unsigned long nr_partial;
struct list_head partial;
#ifdef CONFIG_SLUB_DEBUG
atomic_long_t nr_slabs;
atomic_long_t total_objects;
struct list_head full;
#endif
#endif
};
static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node)
{
return s->node[node];
}
/*
* Iterator over all nodes. The body will be executed for each node that has
* a kmem_cache_node structure allocated (which is true for all online nodes)
*/
#define for_each_kmem_cache_node(__s, __node, __n) \
for (__node = 0; __node < nr_node_ids; __node++) \
if ((__n = get_node(__s, __node)))
#endif
void *slab_start(struct seq_file *m, loff_t *pos);
void *slab_next(struct seq_file *m, void *p, loff_t *pos);
void slab_stop(struct seq_file *m, void *p);
void *memcg_slab_start(struct seq_file *m, loff_t *pos);
void *memcg_slab_next(struct seq_file *m, void *p, loff_t *pos);
void memcg_slab_stop(struct seq_file *m, void *p);
int memcg_slab_show(struct seq_file *m, void *p);
#if defined(CONFIG_SLAB) || defined(CONFIG_SLUB_DEBUG)
void dump_unreclaimable_slab(void);
#else
static inline void dump_unreclaimable_slab(void)
{
}
#endif
void ___cache_free(struct kmem_cache *cache, void *x, unsigned long addr);
#ifdef CONFIG_SLAB_FREELIST_RANDOM
int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count,
gfp_t gfp);
void cache_random_seq_destroy(struct kmem_cache *cachep);
#else
static inline int cache_random_seq_create(struct kmem_cache *cachep,
unsigned int count, gfp_t gfp)
{
return 0;
}
static inline void cache_random_seq_destroy(struct kmem_cache *cachep) { }
#endif /* CONFIG_SLAB_FREELIST_RANDOM */
static inline bool slab_want_init_on_alloc(gfp_t flags, struct kmem_cache *c)
{
if (static_branch_unlikely(&init_on_alloc)) {
if (c->ctor)
return false;
if (c->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON))
return flags & __GFP_ZERO;
return true;
}
return flags & __GFP_ZERO;
}
static inline bool slab_want_init_on_free(struct kmem_cache *c)
{
if (static_branch_unlikely(&init_on_free))
return !(c->ctor ||
(c->flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)));
return false;
}
#endif /* MM_SLAB_H */