Merge branch 'master' into mm-hotfixes-stable

[platform/kernel/linux-starfive.git] / mm / slub.c

// SPDX-License-Identifier: GPL-2.0
/*
 * SLUB: A slab allocator that limits cache line use instead of queuing
 * objects in per cpu and per node lists.
 *
 * The allocator synchronizes using per slab locks or atomic operations
 * and only uses a centralized lock to manage a pool of partial slabs.
 *
 * (C) 2007 SGI, Christoph Lameter
 * (C) 2011 Linux Foundation, Christoph Lameter
 */

#include <linux/mm.h>
#include <linux/swap.h> /* struct reclaim_state */
#include <linux/module.h>
#include <linux/bit_spinlock.h>
#include <linux/interrupt.h>
#include <linux/swab.h>
#include <linux/bitops.h>
#include <linux/slab.h>
#include "slab.h"
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/kasan.h>
#include <linux/kmsan.h>
#include <linux/cpu.h>
#include <linux/cpuset.h>
#include <linux/mempolicy.h>
#include <linux/ctype.h>
#include <linux/stackdepot.h>
#include <linux/debugobjects.h>
#include <linux/kallsyms.h>
#include <linux/kfence.h>
#include <linux/memory.h>
#include <linux/math64.h>
#include <linux/fault-inject.h>
#include <linux/stacktrace.h>
#include <linux/prefetch.h>
#include <linux/memcontrol.h>
#include <linux/random.h>
#include <kunit/test.h>
#include <linux/sort.h>

#include <linux/debugfs.h>
#include <trace/events/kmem.h>

#include "internal.h"

/*
 * Lock order:
 *   1. slab_mutex (Global Mutex)
 *   2. node->list_lock (Spinlock)
 *   3. kmem_cache->cpu_slab->lock (Local lock)
 *   4. slab_lock(slab) (Only on some arches)
 *   5. object_map_lock (Only for debugging)
 *
 *   slab_mutex
 *
 *   The role of the slab_mutex is to protect the list of all the slabs
 *   and to synchronize major metadata changes to slab cache structures.
 *   Also synchronizes memory hotplug callbacks.
 *
 *   slab_lock
 *
 *   The slab_lock is a wrapper around the page lock, thus it is a bit
 *   spinlock.
 *
 *   The slab_lock is only used on arches that do not have the ability
 *   to do a cmpxchg_double. It only protects:
 *
 *      A. slab->freelist       -> List of free objects in a slab
 *      B. slab->inuse          -> Number of objects in use
 *      C. slab->objects        -> Number of objects in slab
 *      D. slab->frozen         -> frozen state
 *
 *   Frozen slabs
 *
 *   If a slab is frozen then it is exempt from list management. It is not
 *   on any list except per cpu partial list. The processor that froze the
 *   slab is the one who can perform list operations on the slab. Other
 *   processors may put objects onto the freelist but the processor that
 *   froze the slab is the only one that can retrieve the objects from the
 *   slab's freelist.
 *
 *   list_lock
 *
 *   The list_lock protects the partial and full list on each node and
 *   the partial slab counter. If taken then no new slabs may be added or
 *   removed from the lists nor make the number of partial slabs be modified.
 *   (Note that the total number of slabs is an atomic value that may be
 *   modified without taking the list lock).
 *
 *   The list_lock is a centralized lock and thus we avoid taking it as
 *   much as possible. As long as SLUB does not have to handle partial
 *   slabs, operations can continue without any centralized lock. F.e.
 *   allocating a long series of objects that fill up slabs does not require
 *   the list lock.
 *
 *   For debug caches, all allocations are forced to go through a list_lock
 *   protected region to serialize against concurrent validation.
 *
 *   cpu_slab->lock local lock
 *
 *   This locks protect slowpath manipulation of all kmem_cache_cpu fields
 *   except the stat counters. This is a percpu structure manipulated only by
 *   the local cpu, so the lock protects against being preempted or interrupted
 *   by an irq. Fast path operations rely on lockless operations instead.
 *
 *   On PREEMPT_RT, the local lock neither disables interrupts nor preemption
 *   which means the lockless fastpath cannot be used as it might interfere with
 *   an in-progress slow path operations. In this case the local lock is always
 *   taken but it still utilizes the freelist for the common operations.
 *
 *   lockless fastpaths
 *
 *   The fast path allocation (slab_alloc_node()) and freeing (do_slab_free())
 *   are fully lockless when satisfied from the percpu slab (and when
 *   cmpxchg_double is possible to use, otherwise slab_lock is taken).
 *   They also don't disable preemption or migration or irqs. They rely on
 *   the transaction id (tid) field to detect being preempted or moved to
 *   another cpu.
 *
 *   irq, preemption, migration considerations
 *
 *   Interrupts are disabled as part of list_lock or local_lock operations, or
 *   around the slab_lock operation, in order to make the slab allocator safe
 *   to use in the context of an irq.
 *
 *   In addition, preemption (or migration on PREEMPT_RT) is disabled in the
 *   allocation slowpath, bulk allocation, and put_cpu_partial(), so that the
 *   local cpu doesn't change in the process and e.g. the kmem_cache_cpu pointer
 *   doesn't have to be revalidated in each section protected by the local lock.
 *
 * SLUB assigns one slab for allocation to each processor.
 * Allocations only occur from these slabs called cpu slabs.
 *
 * Slabs with free elements are kept on a partial list and during regular
 * operations no list for full slabs is used. If an object in a full slab is
 * freed then the slab will show up again on the partial lists.
 * We track full slabs for debugging purposes though because otherwise we
 * cannot scan all objects.
 *
 * Slabs are freed when they become empty. Teardown and setup is
 * minimal so we rely on the page allocators per cpu caches for
 * fast frees and allocs.
 *
 * slab->frozen         The slab is frozen and exempt from list processing.
 *                      This means that the slab is dedicated to a purpose
 *                      such as satisfying allocations for a specific
 *                      processor. Objects may be freed in the slab while
 *                      it is frozen but slab_free will then skip the usual
 *                      list operations. It is up to the processor holding
 *                      the slab to integrate the slab into the slab lists
 *                      when the slab is no longer needed.
 *
 *                      One use of this flag is to mark slabs that are
 *                      used for allocations. Then such a slab becomes a cpu
 *                      slab. The cpu slab may be equipped with an additional
 *                      freelist that allows lockless access to
 *                      free objects in addition to the regular freelist
 *                      that requires the slab lock.
 *
 * SLAB_DEBUG_FLAGS     Slab requires special handling due to debug
 *                      options set. This moves slab handling out of
 *                      the fast path and disables lockless freelists.
 */

/*
 * We could simply use migrate_disable()/enable() but as long as it's a
 * function call even on !PREEMPT_RT, use inline preempt_disable() there.
 */
#ifndef CONFIG_PREEMPT_RT
#define slub_get_cpu_ptr(var)           get_cpu_ptr(var)
#define slub_put_cpu_ptr(var)           put_cpu_ptr(var)
#define USE_LOCKLESS_FAST_PATH()        (true)
#else
#define slub_get_cpu_ptr(var)           \
({                                      \
        migrate_disable();              \
        this_cpu_ptr(var);              \
})
#define slub_put_cpu_ptr(var)           \
do {                                    \
        (void)(var);                    \
        migrate_enable();               \
} while (0)
#define USE_LOCKLESS_FAST_PATH()        (false)
#endif

#ifdef CONFIG_SLUB_DEBUG
#ifdef CONFIG_SLUB_DEBUG_ON
DEFINE_STATIC_KEY_TRUE(slub_debug_enabled);
#else
DEFINE_STATIC_KEY_FALSE(slub_debug_enabled);
#endif
#endif          /* CONFIG_SLUB_DEBUG */

/* Structure holding parameters for get_partial() call chain */
struct partial_context {
        struct slab **slab;
        gfp_t flags;
        unsigned int orig_size;
};

static inline bool kmem_cache_debug(struct kmem_cache *s)
{
        return kmem_cache_debug_flags(s, SLAB_DEBUG_FLAGS);
}

static inline bool slub_debug_orig_size(struct kmem_cache *s)
{
        return (kmem_cache_debug_flags(s, SLAB_STORE_USER) &&
                        (s->flags & SLAB_KMALLOC));
}

void *fixup_red_left(struct kmem_cache *s, void *p)
{
        if (kmem_cache_debug_flags(s, SLAB_RED_ZONE))
                p += s->red_left_pad;

        return p;
}

static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s)
{
#ifdef CONFIG_SLUB_CPU_PARTIAL
        return !kmem_cache_debug(s);
#else
        return false;
#endif
}

/*
 * Issues still to be resolved:
 *
 * - Support PAGE_ALLOC_DEBUG. Should be easy to do.
 *
 * - Variable sizing of the per node arrays
 */

/* Enable to log cmpxchg failures */
#undef SLUB_DEBUG_CMPXCHG

/*
 * Minimum number of partial slabs. These will be left on the partial
 * lists even if they are empty. kmem_cache_shrink may reclaim them.
 */
#define MIN_PARTIAL 5

/*
 * Maximum number of desirable partial slabs.
 * The existence of more partial slabs makes kmem_cache_shrink
 * sort the partial list by the number of objects in use.
 */
#define MAX_PARTIAL 10

#define DEBUG_DEFAULT_FLAGS (SLAB_CONSISTENCY_CHECKS | SLAB_RED_ZONE | \
                                SLAB_POISON | SLAB_STORE_USER)

/*
 * These debug flags cannot use CMPXCHG because there might be consistency
 * issues when checking or reading debug information
 */
#define SLAB_NO_CMPXCHG (SLAB_CONSISTENCY_CHECKS | SLAB_STORE_USER | \
                                SLAB_TRACE)


/*
 * Debugging flags that require metadata to be stored in the slab.  These get
 * disabled when slub_debug=O is used and a cache's min order increases with
 * metadata.
 */
#define DEBUG_METADATA_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)

#define OO_SHIFT        16
#define OO_MASK         ((1 << OO_SHIFT) - 1)
#define MAX_OBJS_PER_PAGE       32767 /* since slab.objects is u15 */

/* Internal SLUB flags */
/* Poison object */
#define __OBJECT_POISON         ((slab_flags_t __force)0x80000000U)
/* Use cmpxchg_double */
#define __CMPXCHG_DOUBLE        ((slab_flags_t __force)0x40000000U)

/*
 * Tracking user of a slab.
 */
#define TRACK_ADDRS_COUNT 16
struct track {
        unsigned long addr;     /* Called from address */
#ifdef CONFIG_STACKDEPOT
        depot_stack_handle_t handle;
#endif
        int cpu;                /* Was running on cpu */
        int pid;                /* Pid context */
        unsigned long when;     /* When did the operation occur */
};

enum track_item { TRACK_ALLOC, TRACK_FREE };

#ifdef CONFIG_SYSFS
static int sysfs_slab_add(struct kmem_cache *);
static int sysfs_slab_alias(struct kmem_cache *, const char *);
#else
static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; }
static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p)
                                                        { return 0; }
#endif

#if defined(CONFIG_DEBUG_FS) && defined(CONFIG_SLUB_DEBUG)
static void debugfs_slab_add(struct kmem_cache *);
#else
static inline void debugfs_slab_add(struct kmem_cache *s) { }
#endif

static inline void stat(const struct kmem_cache *s, enum stat_item si)
{
#ifdef CONFIG_SLUB_STATS
        /*
         * The rmw is racy on a preemptible kernel but this is acceptable, so
         * avoid this_cpu_add()'s irq-disable overhead.
         */
        raw_cpu_inc(s->cpu_slab->stat[si]);
#endif
}

/*
 * Tracks for which NUMA nodes we have kmem_cache_nodes allocated.
 * Corresponds to node_state[N_NORMAL_MEMORY], but can temporarily
 * differ during memory hotplug/hotremove operations.
 * Protected by slab_mutex.
 */
static nodemask_t slab_nodes;

/*
 * Workqueue used for flush_cpu_slab().
 */
static struct workqueue_struct *flushwq;

/********************************************************************
 *                      Core slab cache functions
 *******************************************************************/

/*
 * Returns freelist pointer (ptr). With hardening, this is obfuscated
 * with an XOR of the address where the pointer is held and a per-cache
 * random number.
 */
static inline void *freelist_ptr(const struct kmem_cache *s, void *ptr,
                                 unsigned long ptr_addr)
{
#ifdef CONFIG_SLAB_FREELIST_HARDENED
        /*
         * When CONFIG_KASAN_SW/HW_TAGS is enabled, ptr_addr might be tagged.
         * Normally, this doesn't cause any issues, as both set_freepointer()
         * and get_freepointer() are called with a pointer with the same tag.
         * However, there are some issues with CONFIG_SLUB_DEBUG code. For
         * example, when __free_slub() iterates over objects in a cache, it
         * passes untagged pointers to check_object(). check_object() in turns
         * calls get_freepointer() with an untagged pointer, which causes the
         * freepointer to be restored incorrectly.
         */
        return (void *)((unsigned long)ptr ^ s->random ^
                        swab((unsigned long)kasan_reset_tag((void *)ptr_addr)));
#else
        return ptr;
#endif
}

/* Returns the freelist pointer recorded at location ptr_addr. */
static inline void *freelist_dereference(const struct kmem_cache *s,
                                         void *ptr_addr)
{
        return freelist_ptr(s, (void *)*(unsigned long *)(ptr_addr),
                            (unsigned long)ptr_addr);
}

static inline void *get_freepointer(struct kmem_cache *s, void *object)
{
        object = kasan_reset_tag(object);
        return freelist_dereference(s, object + s->offset);
}

static void prefetch_freepointer(const struct kmem_cache *s, void *object)
{
        prefetchw(object + s->offset);
}

/*
 * When running under KMSAN, get_freepointer_safe() may return an uninitialized
 * pointer value in the case the current thread loses the race for the next
 * memory chunk in the freelist. In that case this_cpu_cmpxchg_double() in
 * slab_alloc_node() will fail, so the uninitialized value won't be used, but
 * KMSAN will still check all arguments of cmpxchg because of imperfect
 * handling of inline assembly.
 * To work around this problem, we apply __no_kmsan_checks to ensure that
 * get_freepointer_safe() returns initialized memory.
 */
__no_kmsan_checks
static inline void *get_freepointer_safe(struct kmem_cache *s, void *object)
{
        unsigned long freepointer_addr;
        void *p;

        if (!debug_pagealloc_enabled_static())
                return get_freepointer(s, object);

        object = kasan_reset_tag(object);
        freepointer_addr = (unsigned long)object + s->offset;
        copy_from_kernel_nofault(&p, (void **)freepointer_addr, sizeof(p));
        return freelist_ptr(s, p, freepointer_addr);
}

static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp)
{
        unsigned long freeptr_addr = (unsigned long)object + s->offset;

#ifdef CONFIG_SLAB_FREELIST_HARDENED
        BUG_ON(object == fp); /* naive detection of double free or corruption */
#endif

        freeptr_addr = (unsigned long)kasan_reset_tag((void *)freeptr_addr);
        *(void **)freeptr_addr = freelist_ptr(s, fp, freeptr_addr);
}

/* Loop over all objects in a slab */
#define for_each_object(__p, __s, __addr, __objects) \
        for (__p = fixup_red_left(__s, __addr); \
                __p < (__addr) + (__objects) * (__s)->size; \
                __p += (__s)->size)

static inline unsigned int order_objects(unsigned int order, unsigned int size)
{
        return ((unsigned int)PAGE_SIZE << order) / size;
}

static inline struct kmem_cache_order_objects oo_make(unsigned int order,
                unsigned int size)
{
        struct kmem_cache_order_objects x = {
                (order << OO_SHIFT) + order_objects(order, size)
        };

        return x;
}

static inline unsigned int oo_order(struct kmem_cache_order_objects x)
{
        return x.x >> OO_SHIFT;
}

static inline unsigned int oo_objects(struct kmem_cache_order_objects x)
{
        return x.x & OO_MASK;
}

#ifdef CONFIG_SLUB_CPU_PARTIAL
static void slub_set_cpu_partial(struct kmem_cache *s, unsigned int nr_objects)
{
        unsigned int nr_slabs;

        s->cpu_partial = nr_objects;

        /*
         * We take the number of objects but actually limit the number of
         * slabs on the per cpu partial list, in order to limit excessive
         * growth of the list. For simplicity we assume that the slabs will
         * be half-full.
         */
        nr_slabs = DIV_ROUND_UP(nr_objects * 2, oo_objects(s->oo));
        s->cpu_partial_slabs = nr_slabs;
}
#else
static inline void
slub_set_cpu_partial(struct kmem_cache *s, unsigned int nr_objects)
{
}
#endif /* CONFIG_SLUB_CPU_PARTIAL */

/*
 * Per slab locking using the pagelock
 */
static __always_inline void slab_lock(struct slab *slab)
{
        struct page *page = slab_page(slab);

        VM_BUG_ON_PAGE(PageTail(page), page);
        bit_spin_lock(PG_locked, &page->flags);
}

static __always_inline void slab_unlock(struct slab *slab)
{
        struct page *page = slab_page(slab);

        VM_BUG_ON_PAGE(PageTail(page), page);
        __bit_spin_unlock(PG_locked, &page->flags);
}

/*
 * Interrupts must be disabled (for the fallback code to work right), typically
 * by an _irqsave() lock variant. On PREEMPT_RT the preempt_disable(), which is
 * part of bit_spin_lock(), is sufficient because the policy is not to allow any
 * allocation/ free operation in hardirq context. Therefore nothing can
 * interrupt the operation.
 */
static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct slab *slab,
                void *freelist_old, unsigned long counters_old,
                void *freelist_new, unsigned long counters_new,
                const char *n)
{
        if (USE_LOCKLESS_FAST_PATH())
                lockdep_assert_irqs_disabled();
#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
    defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
        if (s->flags & __CMPXCHG_DOUBLE) {
                if (cmpxchg_double(&slab->freelist, &slab->counters,
                                   freelist_old, counters_old,
                                   freelist_new, counters_new))
                        return true;
        } else
#endif
        {
                slab_lock(slab);
                if (slab->freelist == freelist_old &&
                                        slab->counters == counters_old) {
                        slab->freelist = freelist_new;
                        slab->counters = counters_new;
                        slab_unlock(slab);
                        return true;
                }
                slab_unlock(slab);
        }

        cpu_relax();
        stat(s, CMPXCHG_DOUBLE_FAIL);

#ifdef SLUB_DEBUG_CMPXCHG
        pr_info("%s %s: cmpxchg double redo ", n, s->name);
#endif

        return false;
}

static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct slab *slab,
                void *freelist_old, unsigned long counters_old,
                void *freelist_new, unsigned long counters_new,
                const char *n)
{
#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
    defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
        if (s->flags & __CMPXCHG_DOUBLE) {
                if (cmpxchg_double(&slab->freelist, &slab->counters,
                                   freelist_old, counters_old,
                                   freelist_new, counters_new))
                        return true;
        } else
#endif
        {
                unsigned long flags;

                local_irq_save(flags);
                slab_lock(slab);
                if (slab->freelist == freelist_old &&
                                        slab->counters == counters_old) {
                        slab->freelist = freelist_new;
                        slab->counters = counters_new;
                        slab_unlock(slab);
                        local_irq_restore(flags);
                        return true;
                }
                slab_unlock(slab);
                local_irq_restore(flags);
        }

        cpu_relax();
        stat(s, CMPXCHG_DOUBLE_FAIL);

#ifdef SLUB_DEBUG_CMPXCHG
        pr_info("%s %s: cmpxchg double redo ", n, s->name);
#endif

        return false;
}

#ifdef CONFIG_SLUB_DEBUG
static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)];
static DEFINE_SPINLOCK(object_map_lock);

static void __fill_map(unsigned long *obj_map, struct kmem_cache *s,
                       struct slab *slab)
{
        void *addr = slab_address(slab);
        void *p;

        bitmap_zero(obj_map, slab->objects);

        for (p = slab->freelist; p; p = get_freepointer(s, p))
                set_bit(__obj_to_index(s, addr, p), obj_map);
}

#if IS_ENABLED(CONFIG_KUNIT)
static bool slab_add_kunit_errors(void)
{
        struct kunit_resource *resource;

        if (likely(!current->kunit_test))
                return false;

        resource = kunit_find_named_resource(current->kunit_test, "slab_errors");
        if (!resource)
                return false;

        (*(int *)resource->data)++;
        kunit_put_resource(resource);
        return true;
}
#else
static inline bool slab_add_kunit_errors(void) { return false; }
#endif

static inline unsigned int size_from_object(struct kmem_cache *s)
{
        if (s->flags & SLAB_RED_ZONE)
                return s->size - s->red_left_pad;

        return s->size;
}

static inline void *restore_red_left(struct kmem_cache *s, void *p)
{
        if (s->flags & SLAB_RED_ZONE)
                p -= s->red_left_pad;

        return p;
}

/*
 * Debug settings:
 */
#if defined(CONFIG_SLUB_DEBUG_ON)
static slab_flags_t slub_debug = DEBUG_DEFAULT_FLAGS;
#else
static slab_flags_t slub_debug;
#endif

static char *slub_debug_string;
static int disable_higher_order_debug;

/*
 * slub is about to manipulate internal object metadata.  This memory lies
 * outside the range of the allocated object, so accessing it would normally
 * be reported by kasan as a bounds error.  metadata_access_enable() is used
 * to tell kasan that these accesses are OK.
 */
static inline void metadata_access_enable(void)
{
        kasan_disable_current();
}

static inline void metadata_access_disable(void)
{
        kasan_enable_current();
}

/*
 * Object debugging
 */

/* Verify that a pointer has an address that is valid within a slab page */
static inline int check_valid_pointer(struct kmem_cache *s,
                                struct slab *slab, void *object)
{
        void *base;

        if (!object)
                return 1;

        base = slab_address(slab);
        object = kasan_reset_tag(object);
        object = restore_red_left(s, object);
        if (object < base || object >= base + slab->objects * s->size ||
                (object - base) % s->size) {
                return 0;
        }

        return 1;
}

static void print_section(char *level, char *text, u8 *addr,
                          unsigned int length)
{
        metadata_access_enable();
        print_hex_dump(level, text, DUMP_PREFIX_ADDRESS,
                        16, 1, kasan_reset_tag((void *)addr), length, 1);
        metadata_access_disable();
}

/*
 * See comment in calculate_sizes().
 */
static inline bool freeptr_outside_object(struct kmem_cache *s)
{
        return s->offset >= s->inuse;
}

/*
 * Return offset of the end of info block which is inuse + free pointer if
 * not overlapping with object.
 */
static inline unsigned int get_info_end(struct kmem_cache *s)
{
        if (freeptr_outside_object(s))
                return s->inuse + sizeof(void *);
        else
                return s->inuse;
}

static struct track *get_track(struct kmem_cache *s, void *object,
        enum track_item alloc)
{
        struct track *p;

        p = object + get_info_end(s);

        return kasan_reset_tag(p + alloc);
}

#ifdef CONFIG_STACKDEPOT
static noinline depot_stack_handle_t set_track_prepare(void)
{
        depot_stack_handle_t handle;
        unsigned long entries[TRACK_ADDRS_COUNT];
        unsigned int nr_entries;

        nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 3);
        handle = stack_depot_save(entries, nr_entries, GFP_NOWAIT);

        return handle;
}
#else
static inline depot_stack_handle_t set_track_prepare(void)
{
        return 0;
}
#endif

static void set_track_update(struct kmem_cache *s, void *object,
                             enum track_item alloc, unsigned long addr,
                             depot_stack_handle_t handle)
{
        struct track *p = get_track(s, object, alloc);

#ifdef CONFIG_STACKDEPOT
        p->handle = handle;
#endif
        p->addr = addr;
        p->cpu = smp_processor_id();
        p->pid = current->pid;
        p->when = jiffies;
}

static __always_inline void set_track(struct kmem_cache *s, void *object,
                                      enum track_item alloc, unsigned long addr)
{
        depot_stack_handle_t handle = set_track_prepare();

        set_track_update(s, object, alloc, addr, handle);
}

static void init_tracking(struct kmem_cache *s, void *object)
{
        struct track *p;

        if (!(s->flags & SLAB_STORE_USER))
                return;

        p = get_track(s, object, TRACK_ALLOC);
        memset(p, 0, 2*sizeof(struct track));
}

static void print_track(const char *s, struct track *t, unsigned long pr_time)
{
        depot_stack_handle_t handle __maybe_unused;

        if (!t->addr)
                return;

        pr_err("%s in %pS age=%lu cpu=%u pid=%d\n",
               s, (void *)t->addr, pr_time - t->when, t->cpu, t->pid);
#ifdef CONFIG_STACKDEPOT
        handle = READ_ONCE(t->handle);
        if (handle)
                stack_depot_print(handle);
        else
                pr_err("object allocation/free stack trace missing\n");
#endif
}

void print_tracking(struct kmem_cache *s, void *object)
{
        unsigned long pr_time = jiffies;
        if (!(s->flags & SLAB_STORE_USER))
                return;

        print_track("Allocated", get_track(s, object, TRACK_ALLOC), pr_time);
        print_track("Freed", get_track(s, object, TRACK_FREE), pr_time);
}

static void print_slab_info(const struct slab *slab)
{
        struct folio *folio = (struct folio *)slab_folio(slab);

        pr_err("Slab 0x%p objects=%u used=%u fp=0x%p flags=%pGp\n",
               slab, slab->objects, slab->inuse, slab->freelist,
               folio_flags(folio, 0));
}

/*
 * kmalloc caches has fixed sizes (mostly power of 2), and kmalloc() API
 * family will round up the real request size to these fixed ones, so
 * there could be an extra area than what is requested. Save the original
 * request size in the meta data area, for better debug and sanity check.
 */
static inline void set_orig_size(struct kmem_cache *s,
                                void *object, unsigned int orig_size)
{
        void *p = kasan_reset_tag(object);

        if (!slub_debug_orig_size(s))
                return;

        p += get_info_end(s);
        p += sizeof(struct track) * 2;

        *(unsigned int *)p = orig_size;
}

static inline unsigned int get_orig_size(struct kmem_cache *s, void *object)
{
        void *p = kasan_reset_tag(object);

        if (!slub_debug_orig_size(s))
                return s->object_size;

        p += get_info_end(s);
        p += sizeof(struct track) * 2;

        return *(unsigned int *)p;
}

static void slab_bug(struct kmem_cache *s, char *fmt, ...)
{
        struct va_format vaf;
        va_list args;

        va_start(args, fmt);
        vaf.fmt = fmt;
        vaf.va = &args;
        pr_err("=============================================================================\n");
        pr_err("BUG %s (%s): %pV\n", s->name, print_tainted(), &vaf);
        pr_err("-----------------------------------------------------------------------------\n\n");
        va_end(args);
}

__printf(2, 3)
static void slab_fix(struct kmem_cache *s, char *fmt, ...)
{
        struct va_format vaf;
        va_list args;

        if (slab_add_kunit_errors())
                return;

        va_start(args, fmt);
        vaf.fmt = fmt;
        vaf.va = &args;
        pr_err("FIX %s: %pV\n", s->name, &vaf);
        va_end(args);
}

static void print_trailer(struct kmem_cache *s, struct slab *slab, u8 *p)
{
        unsigned int off;       /* Offset of last byte */
        u8 *addr = slab_address(slab);

        print_tracking(s, p);

        print_slab_info(slab);

        pr_err("Object 0x%p @offset=%tu fp=0x%p\n\n",
               p, p - addr, get_freepointer(s, p));

        if (s->flags & SLAB_RED_ZONE)
                print_section(KERN_ERR, "Redzone  ", p - s->red_left_pad,
                              s->red_left_pad);
        else if (p > addr + 16)
                print_section(KERN_ERR, "Bytes b4 ", p - 16, 16);

        print_section(KERN_ERR,         "Object   ", p,
                      min_t(unsigned int, s->object_size, PAGE_SIZE));
        if (s->flags & SLAB_RED_ZONE)
                print_section(KERN_ERR, "Redzone  ", p + s->object_size,
                        s->inuse - s->object_size);

        off = get_info_end(s);

        if (s->flags & SLAB_STORE_USER)
                off += 2 * sizeof(struct track);

        if (slub_debug_orig_size(s))
                off += sizeof(unsigned int);

        off += kasan_metadata_size(s);

        if (off != size_from_object(s))
                /* Beginning of the filler is the free pointer */
                print_section(KERN_ERR, "Padding  ", p + off,
                              size_from_object(s) - off);

        dump_stack();
}

static void object_err(struct kmem_cache *s, struct slab *slab,
                        u8 *object, char *reason)
{
        if (slab_add_kunit_errors())
                return;

        slab_bug(s, "%s", reason);
        print_trailer(s, slab, object);
        add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
}

static bool freelist_corrupted(struct kmem_cache *s, struct slab *slab,
                               void **freelist, void *nextfree)
{
        if ((s->flags & SLAB_CONSISTENCY_CHECKS) &&
            !check_valid_pointer(s, slab, nextfree) && freelist) {
                object_err(s, slab, *freelist, "Freechain corrupt");
                *freelist = NULL;
                slab_fix(s, "Isolate corrupted freechain");
                return true;
        }

        return false;
}

static __printf(3, 4) void slab_err(struct kmem_cache *s, struct slab *slab,
                        const char *fmt, ...)
{
        va_list args;
        char buf[100];

        if (slab_add_kunit_errors())
                return;

        va_start(args, fmt);
        vsnprintf(buf, sizeof(buf), fmt, args);
        va_end(args);
        slab_bug(s, "%s", buf);
        print_slab_info(slab);
        dump_stack();
        add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
}

static void init_object(struct kmem_cache *s, void *object, u8 val)
{
        u8 *p = kasan_reset_tag(object);

        if (s->flags & SLAB_RED_ZONE)
                memset(p - s->red_left_pad, val, s->red_left_pad);

        if (s->flags & __OBJECT_POISON) {
                memset(p, POISON_FREE, s->object_size - 1);
                p[s->object_size - 1] = POISON_END;
        }

        if (s->flags & SLAB_RED_ZONE)
                memset(p + s->object_size, val, s->inuse - s->object_size);
}

static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
                                                void *from, void *to)
{
        slab_fix(s, "Restoring %s 0x%p-0x%p=0x%x", message, from, to - 1, data);
        memset(from, data, to - from);
}

static int check_bytes_and_report(struct kmem_cache *s, struct slab *slab,
                        u8 *object, char *what,
                        u8 *start, unsigned int value, unsigned int bytes)
{
        u8 *fault;
        u8 *end;
        u8 *addr = slab_address(slab);

        metadata_access_enable();
        fault = memchr_inv(kasan_reset_tag(start), value, bytes);
        metadata_access_disable();
        if (!fault)
                return 1;

        end = start + bytes;
        while (end > fault && end[-1] == value)
                end--;

        if (slab_add_kunit_errors())
                goto skip_bug_print;

        slab_bug(s, "%s overwritten", what);
        pr_err("0x%p-0x%p @offset=%tu. First byte 0x%x instead of 0x%x\n",
                                        fault, end - 1, fault - addr,
                                        fault[0], value);
        print_trailer(s, slab, object);
        add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);

skip_bug_print:
        restore_bytes(s, what, value, fault, end);
        return 0;
}

/*
 * Object layout:
 *
 * object address
 *      Bytes of the object to be managed.
 *      If the freepointer may overlay the object then the free
 *      pointer is at the middle of the object.
 *
 *      Poisoning uses 0x6b (POISON_FREE) and the last byte is
 *      0xa5 (POISON_END)
 *
 * object + s->object_size
 *      Padding to reach word boundary. This is also used for Redzoning.
 *      Padding is extended by another word if Redzoning is enabled and
 *      object_size == inuse.
 *
 *      We fill with 0xbb (RED_INACTIVE) for inactive objects and with
 *      0xcc (RED_ACTIVE) for objects in use.
 *
 * object + s->inuse
 *      Meta data starts here.
 *
 *      A. Free pointer (if we cannot overwrite object on free)
 *      B. Tracking data for SLAB_STORE_USER
 *      C. Original request size for kmalloc object (SLAB_STORE_USER enabled)
 *      D. Padding to reach required alignment boundary or at minimum
 *              one word if debugging is on to be able to detect writes
 *              before the word boundary.
 *
 *      Padding is done using 0x5a (POISON_INUSE)
 *
 * object + s->size
 *      Nothing is used beyond s->size.
 *
 * If slabcaches are merged then the object_size and inuse boundaries are mostly
 * ignored. And therefore no slab options that rely on these boundaries
 * may be used with merged slabcaches.
 */

static int check_pad_bytes(struct kmem_cache *s, struct slab *slab, u8 *p)
{
        unsigned long off = get_info_end(s);    /* The end of info */

        if (s->flags & SLAB_STORE_USER) {
                /* We also have user information there */
                off += 2 * sizeof(struct track);

                if (s->flags & SLAB_KMALLOC)
                        off += sizeof(unsigned int);
        }

        off += kasan_metadata_size(s);

        if (size_from_object(s) == off)
                return 1;

        return check_bytes_and_report(s, slab, p, "Object padding",
                        p + off, POISON_INUSE, size_from_object(s) - off);
}

/* Check the pad bytes at the end of a slab page */
static void slab_pad_check(struct kmem_cache *s, struct slab *slab)
{
        u8 *start;
        u8 *fault;
        u8 *end;
        u8 *pad;
        int length;
        int remainder;

        if (!(s->flags & SLAB_POISON))
                return;

        start = slab_address(slab);
        length = slab_size(slab);
        end = start + length;
        remainder = length % s->size;
        if (!remainder)
                return;

        pad = end - remainder;
        metadata_access_enable();
        fault = memchr_inv(kasan_reset_tag(pad), POISON_INUSE, remainder);
        metadata_access_disable();
        if (!fault)
                return;
        while (end > fault && end[-1] == POISON_INUSE)
                end--;

        slab_err(s, slab, "Padding overwritten. 0x%p-0x%p @offset=%tu",
                        fault, end - 1, fault - start);
        print_section(KERN_ERR, "Padding ", pad, remainder);

        restore_bytes(s, "slab padding", POISON_INUSE, fault, end);
}

static int check_object(struct kmem_cache *s, struct slab *slab,
                                        void *object, u8 val)
{
        u8 *p = object;
        u8 *endobject = object + s->object_size;

        if (s->flags & SLAB_RED_ZONE) {
                if (!check_bytes_and_report(s, slab, object, "Left Redzone",
                        object - s->red_left_pad, val, s->red_left_pad))
                        return 0;

                if (!check_bytes_and_report(s, slab, object, "Right Redzone",
                        endobject, val, s->inuse - s->object_size))
                        return 0;
        } else {
                if ((s->flags & SLAB_POISON) && s->object_size < s->inuse) {
                        check_bytes_and_report(s, slab, p, "Alignment padding",
                                endobject, POISON_INUSE,
                                s->inuse - s->object_size);
                }
        }

        if (s->flags & SLAB_POISON) {
                if (val != SLUB_RED_ACTIVE && (s->flags & __OBJECT_POISON) &&
                        (!check_bytes_and_report(s, slab, p, "Poison", p,
                                        POISON_FREE, s->object_size - 1) ||
                         !check_bytes_and_report(s, slab, p, "End Poison",
                                p + s->object_size - 1, POISON_END, 1)))
                        return 0;
                /*
                 * check_pad_bytes cleans up on its own.
                 */
                check_pad_bytes(s, slab, p);
        }

        if (!freeptr_outside_object(s) && val == SLUB_RED_ACTIVE)
                /*
                 * Object and freepointer overlap. Cannot check
                 * freepointer while object is allocated.
                 */
                return 1;

        /* Check free pointer validity */
        if (!check_valid_pointer(s, slab, get_freepointer(s, p))) {
                object_err(s, slab, p, "Freepointer corrupt");
                /*
                 * No choice but to zap it and thus lose the remainder
                 * of the free objects in this slab. May cause
                 * another error because the object count is now wrong.
                 */
                set_freepointer(s, p, NULL);
                return 0;
        }
        return 1;
}

static int check_slab(struct kmem_cache *s, struct slab *slab)
{
        int maxobj;

        if (!folio_test_slab(slab_folio(slab))) {
                slab_err(s, slab, "Not a valid slab page");
                return 0;
        }

        maxobj = order_objects(slab_order(slab), s->size);
        if (slab->objects > maxobj) {
                slab_err(s, slab, "objects %u > max %u",
                        slab->objects, maxobj);
                return 0;
        }
        if (slab->inuse > slab->objects) {
                slab_err(s, slab, "inuse %u > max %u",
                        slab->inuse, slab->objects);
                return 0;
        }
        /* Slab_pad_check fixes things up after itself */
        slab_pad_check(s, slab);
        return 1;
}

/*
 * Determine if a certain object in a slab is on the freelist. Must hold the
 * slab lock to guarantee that the chains are in a consistent state.
 */
static int on_freelist(struct kmem_cache *s, struct slab *slab, void *search)
{
        int nr = 0;
        void *fp;
        void *object = NULL;
        int max_objects;

        fp = slab->freelist;
        while (fp && nr <= slab->objects) {
                if (fp == search)
                        return 1;
                if (!check_valid_pointer(s, slab, fp)) {
                        if (object) {
                                object_err(s, slab, object,
                                        "Freechain corrupt");
                                set_freepointer(s, object, NULL);
                        } else {
                                slab_err(s, slab, "Freepointer corrupt");
                                slab->freelist = NULL;
                                slab->inuse = slab->objects;
                                slab_fix(s, "Freelist cleared");
                                return 0;
                        }
                        break;
                }
                object = fp;
                fp = get_freepointer(s, object);
                nr++;
        }

        max_objects = order_objects(slab_order(slab), s->size);
        if (max_objects > MAX_OBJS_PER_PAGE)
                max_objects = MAX_OBJS_PER_PAGE;

        if (slab->objects != max_objects) {
                slab_err(s, slab, "Wrong number of objects. Found %d but should be %d",
                         slab->objects, max_objects);
                slab->objects = max_objects;
                slab_fix(s, "Number of objects adjusted");
        }
        if (slab->inuse != slab->objects - nr) {
                slab_err(s, slab, "Wrong object count. Counter is %d but counted were %d",
                         slab->inuse, slab->objects - nr);
                slab->inuse = slab->objects - nr;
                slab_fix(s, "Object count adjusted");
        }
        return search == NULL;
}

static void trace(struct kmem_cache *s, struct slab *slab, void *object,
                                                                int alloc)
{
        if (s->flags & SLAB_TRACE) {
                pr_info("TRACE %s %s 0x%p inuse=%d fp=0x%p\n",
                        s->name,
                        alloc ? "alloc" : "free",
                        object, slab->inuse,
                        slab->freelist);

                if (!alloc)
                        print_section(KERN_INFO, "Object ", (void *)object,
                                        s->object_size);

                dump_stack();
        }
}

/*
 * Tracking of fully allocated slabs for debugging purposes.
 */
static void add_full(struct kmem_cache *s,
        struct kmem_cache_node *n, struct slab *slab)
{
        if (!(s->flags & SLAB_STORE_USER))
                return;

        lockdep_assert_held(&n->list_lock);
        list_add(&slab->slab_list, &n->full);
}

static void remove_full(struct kmem_cache *s, struct kmem_cache_node *n, struct slab *slab)
{
        if (!(s->flags & SLAB_STORE_USER))
                return;

        lockdep_assert_held(&n->list_lock);
        list_del(&slab->slab_list);
}

/* Tracking of the number of slabs for debugging purposes */
static inline unsigned long slabs_node(struct kmem_cache *s, int node)
{
        struct kmem_cache_node *n = get_node(s, node);

        return atomic_long_read(&n->nr_slabs);
}

static inline unsigned long node_nr_slabs(struct kmem_cache_node *n)
{
        return atomic_long_read(&n->nr_slabs);
}

static inline void inc_slabs_node(struct kmem_cache *s, int node, int objects)
{
        struct kmem_cache_node *n = get_node(s, node);

        /*
         * May be called early in order to allocate a slab for the
         * kmem_cache_node structure. Solve the chicken-egg
         * dilemma by deferring the increment of the count during
         * bootstrap (see early_kmem_cache_node_alloc).
         */
        if (likely(n)) {
                atomic_long_inc(&n->nr_slabs);
                atomic_long_add(objects, &n->total_objects);
        }
}
static inline void dec_slabs_node(struct kmem_cache *s, int node, int objects)
{
        struct kmem_cache_node *n = get_node(s, node);

        atomic_long_dec(&n->nr_slabs);
        atomic_long_sub(objects, &n->total_objects);
}

/* Object debug checks for alloc/free paths */
static void setup_object_debug(struct kmem_cache *s, void *object)
{
        if (!kmem_cache_debug_flags(s, SLAB_STORE_USER|SLAB_RED_ZONE|__OBJECT_POISON))
                return;

        init_object(s, object, SLUB_RED_INACTIVE);
        init_tracking(s, object);
}

static
void setup_slab_debug(struct kmem_cache *s, struct slab *slab, void *addr)
{
        if (!kmem_cache_debug_flags(s, SLAB_POISON))
                return;

        metadata_access_enable();
        memset(kasan_reset_tag(addr), POISON_INUSE, slab_size(slab));
        metadata_access_disable();
}

static inline int alloc_consistency_checks(struct kmem_cache *s,
                                        struct slab *slab, void *object)
{
        if (!check_slab(s, slab))
                return 0;

        if (!check_valid_pointer(s, slab, object)) {
                object_err(s, slab, object, "Freelist Pointer check fails");
                return 0;
        }

        if (!check_object(s, slab, object, SLUB_RED_INACTIVE))
                return 0;

        return 1;
}

static noinline int alloc_debug_processing(struct kmem_cache *s,
                        struct slab *slab, void *object, int orig_size)
{
        if (s->flags & SLAB_CONSISTENCY_CHECKS) {
                if (!alloc_consistency_checks(s, slab, object))
                        goto bad;
        }

        /* Success. Perform special debug activities for allocs */
        trace(s, slab, object, 1);
        set_orig_size(s, object, orig_size);
        init_object(s, object, SLUB_RED_ACTIVE);
        return 1;

bad:
        if (folio_test_slab(slab_folio(slab))) {
                /*
                 * If this is a slab page then lets do the best we can
                 * to avoid issues in the future. Marking all objects
                 * as used avoids touching the remaining objects.
                 */
                slab_fix(s, "Marking all objects used");
                slab->inuse = slab->objects;
                slab->freelist = NULL;
        }
        return 0;
}

static inline int free_consistency_checks(struct kmem_cache *s,
                struct slab *slab, void *object, unsigned long addr)
{
        if (!check_valid_pointer(s, slab, object)) {
                slab_err(s, slab, "Invalid object pointer 0x%p", object);
                return 0;
        }

        if (on_freelist(s, slab, object)) {
                object_err(s, slab, object, "Object already free");
                return 0;
        }

        if (!check_object(s, slab, object, SLUB_RED_ACTIVE))
                return 0;

        if (unlikely(s != slab->slab_cache)) {
                if (!folio_test_slab(slab_folio(slab))) {
                        slab_err(s, slab, "Attempt to free object(0x%p) outside of slab",
                                 object);
                } else if (!slab->slab_cache) {
                        pr_err("SLUB <none>: no slab for object 0x%p.\n",
                               object);
                        dump_stack();
                } else
                        object_err(s, slab, object,
                                        "page slab pointer corrupt.");
                return 0;
        }
        return 1;
}

/*
 * Parse a block of slub_debug options. Blocks are delimited by ';'
 *
 * @str:    start of block
 * @flags:  returns parsed flags, or DEBUG_DEFAULT_FLAGS if none specified
 * @slabs:  return start of list of slabs, or NULL when there's no list
 * @init:   assume this is initial parsing and not per-kmem-create parsing
 *
 * returns the start of next block if there's any, or NULL
 */
static char *
parse_slub_debug_flags(char *str, slab_flags_t *flags, char **slabs, bool init)
{
        bool higher_order_disable = false;

        /* Skip any completely empty blocks */
        while (*str && *str == ';')
                str++;

        if (*str == ',') {
                /*
                 * No options but restriction on slabs. This means full
                 * debugging for slabs matching a pattern.
                 */
                *flags = DEBUG_DEFAULT_FLAGS;
                goto check_slabs;
        }
        *flags = 0;

        /* Determine which debug features should be switched on */
        for (; *str && *str != ',' && *str != ';'; str++) {
                switch (tolower(*str)) {
                case '-':
                        *flags = 0;
                        break;
                case 'f':
                        *flags |= SLAB_CONSISTENCY_CHECKS;
                        break;
                case 'z':
                        *flags |= SLAB_RED_ZONE;
                        break;
                case 'p':
                        *flags |= SLAB_POISON;
                        break;
                case 'u':
                        *flags |= SLAB_STORE_USER;
                        break;
                case 't':
                        *flags |= SLAB_TRACE;
                        break;
                case 'a':
                        *flags |= SLAB_FAILSLAB;
                        break;
                case 'o':
                        /*
                         * Avoid enabling debugging on caches if its minimum
                         * order would increase as a result.
                         */
                        higher_order_disable = true;
                        break;
                default:
                        if (init)
                                pr_err("slub_debug option '%c' unknown. skipped\n", *str);
                }
        }
check_slabs:
        if (*str == ',')
                *slabs = ++str;
        else
                *slabs = NULL;

        /* Skip over the slab list */
        while (*str && *str != ';')
                str++;

        /* Skip any completely empty blocks */
        while (*str && *str == ';')
                str++;

        if (init && higher_order_disable)
                disable_higher_order_debug = 1;

        if (*str)
                return str;
        else
                return NULL;
}

static int __init setup_slub_debug(char *str)
{
        slab_flags_t flags;
        slab_flags_t global_flags;
        char *saved_str;
        char *slab_list;
        bool global_slub_debug_changed = false;
        bool slab_list_specified = false;

        global_flags = DEBUG_DEFAULT_FLAGS;
        if (*str++ != '=' || !*str)
                /*
                 * No options specified. Switch on full debugging.
                 */
                goto out;

        saved_str = str;
        while (str) {
                str = parse_slub_debug_flags(str, &flags, &slab_list, true);

                if (!slab_list) {
                        global_flags = flags;
                        global_slub_debug_changed = true;
                } else {
                        slab_list_specified = true;
                        if (flags & SLAB_STORE_USER)
                                stack_depot_want_early_init();
                }
        }

        /*
         * For backwards compatibility, a single list of flags with list of
         * slabs means debugging is only changed for those slabs, so the global
         * slub_debug should be unchanged (0 or DEBUG_DEFAULT_FLAGS, depending
         * on CONFIG_SLUB_DEBUG_ON). We can extended that to multiple lists as
         * long as there is no option specifying flags without a slab list.
         */
        if (slab_list_specified) {
                if (!global_slub_debug_changed)
                        global_flags = slub_debug;
                slub_debug_string = saved_str;
        }
out:
        slub_debug = global_flags;
        if (slub_debug & SLAB_STORE_USER)
                stack_depot_want_early_init();
        if (slub_debug != 0 || slub_debug_string)
                static_branch_enable(&slub_debug_enabled);
        else
                static_branch_disable(&slub_debug_enabled);
        if ((static_branch_unlikely(&init_on_alloc) ||
             static_branch_unlikely(&init_on_free)) &&
            (slub_debug & SLAB_POISON))
                pr_info("mem auto-init: SLAB_POISON will take precedence over init_on_alloc/init_on_free\n");
        return 1;
}

__setup("slub_debug", setup_slub_debug);

/*
 * kmem_cache_flags - apply debugging options to the cache
 * @object_size:        the size of an object without meta data
 * @flags:              flags to set
 * @name:               name of the cache
 *
 * Debug option(s) are applied to @flags. In addition to the debug
 * option(s), if a slab name (or multiple) is specified i.e.
 * slub_debug=<Debug-Options>,<slab name1>,<slab name2> ...
 * then only the select slabs will receive the debug option(s).
 */
slab_flags_t kmem_cache_flags(unsigned int object_size,
        slab_flags_t flags, const char *name)
{
        char *iter;
        size_t len;
        char *next_block;
        slab_flags_t block_flags;
        slab_flags_t slub_debug_local = slub_debug;

        if (flags & SLAB_NO_USER_FLAGS)
                return flags;

        /*
         * If the slab cache is for debugging (e.g. kmemleak) then
         * don't store user (stack trace) information by default,
         * but let the user enable it via the command line below.
         */
        if (flags & SLAB_NOLEAKTRACE)
                slub_debug_local &= ~SLAB_STORE_USER;

        len = strlen(name);
        next_block = slub_debug_string;
        /* Go through all blocks of debug options, see if any matches our slab's name */
        while (next_block) {
                next_block = parse_slub_debug_flags(next_block, &block_flags, &iter, false);
                if (!iter)
                        continue;
                /* Found a block that has a slab list, search it */
                while (*iter) {
                        char *end, *glob;
                        size_t cmplen;

                        end = strchrnul(iter, ',');
                        if (next_block && next_block < end)
                                end = next_block - 1;

                        glob = strnchr(iter, end - iter, '*');
                        if (glob)
                                cmplen = glob - iter;
                        else
                                cmplen = max_t(size_t, len, (end - iter));

                        if (!strncmp(name, iter, cmplen)) {
                                flags |= block_flags;
                                return flags;
                        }

                        if (!*end || *end == ';')
                                break;
                        iter = end + 1;
                }
        }

        return flags | slub_debug_local;
}
#else /* !CONFIG_SLUB_DEBUG */
static inline void setup_object_debug(struct kmem_cache *s, void *object) {}
static inline
void setup_slab_debug(struct kmem_cache *s, struct slab *slab, void *addr) {}

static inline int alloc_debug_processing(struct kmem_cache *s,
        struct slab *slab, void *object, int orig_size) { return 0; }

static inline void free_debug_processing(
        struct kmem_cache *s, struct slab *slab,
        void *head, void *tail, int bulk_cnt,
        unsigned long addr) {}

static inline void slab_pad_check(struct kmem_cache *s, struct slab *slab) {}
static inline int check_object(struct kmem_cache *s, struct slab *slab,
                        void *object, u8 val) { return 1; }
static inline void set_track(struct kmem_cache *s, void *object,
                             enum track_item alloc, unsigned long addr) {}
static inline void add_full(struct kmem_cache *s, struct kmem_cache_node *n,
                                        struct slab *slab) {}
static inline void remove_full(struct kmem_cache *s, struct kmem_cache_node *n,
                                        struct slab *slab) {}
slab_flags_t kmem_cache_flags(unsigned int object_size,
        slab_flags_t flags, const char *name)
{
        return flags;
}
#define slub_debug 0

#define disable_higher_order_debug 0

static inline unsigned long slabs_node(struct kmem_cache *s, int node)
                                                        { return 0; }
static inline unsigned long node_nr_slabs(struct kmem_cache_node *n)
                                                        { return 0; }
static inline void inc_slabs_node(struct kmem_cache *s, int node,
                                                        int objects) {}
static inline void dec_slabs_node(struct kmem_cache *s, int node,
                                                        int objects) {}

static bool freelist_corrupted(struct kmem_cache *s, struct slab *slab,
                               void **freelist, void *nextfree)
{
        return false;
}
#endif /* CONFIG_SLUB_DEBUG */

/*
 * Hooks for other subsystems that check memory allocations. In a typical
 * production configuration these hooks all should produce no code at all.
 */
static __always_inline bool slab_free_hook(struct kmem_cache *s,
                                                void *x, bool init)
{
        kmemleak_free_recursive(x, s->flags);
        kmsan_slab_free(s, x);

        debug_check_no_locks_freed(x, s->object_size);

        if (!(s->flags & SLAB_DEBUG_OBJECTS))
                debug_check_no_obj_freed(x, s->object_size);

        /* Use KCSAN to help debug racy use-after-free. */
        if (!(s->flags & SLAB_TYPESAFE_BY_RCU))
                __kcsan_check_access(x, s->object_size,
                                     KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ASSERT);

        /*
         * As memory initialization might be integrated into KASAN,
         * kasan_slab_free and initialization memset's must be
         * kept together to avoid discrepancies in behavior.
         *
         * The initialization memset's clear the object and the metadata,
         * but don't touch the SLAB redzone.
         */
        if (init) {
                int rsize;

                if (!kasan_has_integrated_init())
                        memset(kasan_reset_tag(x), 0, s->object_size);
                rsize = (s->flags & SLAB_RED_ZONE) ? s->red_left_pad : 0;
                memset((char *)kasan_reset_tag(x) + s->inuse, 0,
                       s->size - s->inuse - rsize);
        }
        /* KASAN might put x into memory quarantine, delaying its reuse. */
        return kasan_slab_free(s, x, init);
}

static inline bool slab_free_freelist_hook(struct kmem_cache *s,
                                           void **head, void **tail,
                                           int *cnt)
{

        void *object;
        void *next = *head;
        void *old_tail = *tail ? *tail : *head;

        if (is_kfence_address(next)) {
                slab_free_hook(s, next, false);
                return true;
        }

        /* Head and tail of the reconstructed freelist */
        *head = NULL;
        *tail = NULL;

        do {
                object = next;
                next = get_freepointer(s, object);

                /* If object's reuse doesn't have to be delayed */
                if (!slab_free_hook(s, object, slab_want_init_on_free(s))) {
                        /* Move object to the new freelist */
                        set_freepointer(s, object, *head);
                        *head = object;
                        if (!*tail)
                                *tail = object;
                } else {
                        /*
                         * Adjust the reconstructed freelist depth
                         * accordingly if object's reuse is delayed.
                         */
                        --(*cnt);
                }
        } while (object != old_tail);

        if (*head == *tail)
                *tail = NULL;

        return *head != NULL;
}

static void *setup_object(struct kmem_cache *s, void *object)
{
        setup_object_debug(s, object);
        object = kasan_init_slab_obj(s, object);
        if (unlikely(s->ctor)) {
                kasan_unpoison_object_data(s, object);
                s->ctor(object);
                kasan_poison_object_data(s, object);
        }
        return object;
}

/*
 * Slab allocation and freeing
 */
static inline struct slab *alloc_slab_page(gfp_t flags, int node,
                struct kmem_cache_order_objects oo)
{
        struct folio *folio;
        struct slab *slab;
        unsigned int order = oo_order(oo);

        if (node == NUMA_NO_NODE)
                folio = (struct folio *)alloc_pages(flags, order);
        else
                folio = (struct folio *)__alloc_pages_node(node, flags, order);

        if (!folio)
                return NULL;

        slab = folio_slab(folio);
        __folio_set_slab(folio);
        if (page_is_pfmemalloc(folio_page(folio, 0)))
                slab_set_pfmemalloc(slab);

        return slab;
}

#ifdef CONFIG_SLAB_FREELIST_RANDOM
/* Pre-initialize the random sequence cache */
static int init_cache_random_seq(struct kmem_cache *s)
{
        unsigned int count = oo_objects(s->oo);
        int err;

        /* Bailout if already initialised */
        if (s->random_seq)
                return 0;

        err = cache_random_seq_create(s, count, GFP_KERNEL);
        if (err) {
                pr_err("SLUB: Unable to initialize free list for %s\n",
                        s->name);
                return err;
        }

        /* Transform to an offset on the set of pages */
        if (s->random_seq) {
                unsigned int i;

                for (i = 0; i < count; i++)
                        s->random_seq[i] *= s->size;
        }
        return 0;
}

/* Initialize each random sequence freelist per cache */
static void __init init_freelist_randomization(void)
{
        struct kmem_cache *s;

        mutex_lock(&slab_mutex);

        list_for_each_entry(s, &slab_caches, list)
                init_cache_random_seq(s);

        mutex_unlock(&slab_mutex);
}

/* Get the next entry on the pre-computed freelist randomized */
static void *next_freelist_entry(struct kmem_cache *s, struct slab *slab,
                                unsigned long *pos, void *start,
                                unsigned long page_limit,
                                unsigned long freelist_count)
{
        unsigned int idx;

        /*
         * If the target page allocation failed, the number of objects on the
         * page might be smaller than the usual size defined by the cache.
         */
        do {
                idx = s->random_seq[*pos];
                *pos += 1;
                if (*pos >= freelist_count)
                        *pos = 0;
        } while (unlikely(idx >= page_limit));

        return (char *)start + idx;
}

/* Shuffle the single linked freelist based on a random pre-computed sequence */
static bool shuffle_freelist(struct kmem_cache *s, struct slab *slab)
{
        void *start;
        void *cur;
        void *next;
        unsigned long idx, pos, page_limit, freelist_count;

        if (slab->objects < 2 || !s->random_seq)
                return false;

        freelist_count = oo_objects(s->oo);
        pos = prandom_u32_max(freelist_count);

        page_limit = slab->objects * s->size;
        start = fixup_red_left(s, slab_address(slab));

        /* First entry is used as the base of the freelist */
        cur = next_freelist_entry(s, slab, &pos, start, page_limit,
                                freelist_count);
        cur = setup_object(s, cur);
        slab->freelist = cur;

        for (idx = 1; idx < slab->objects; idx++) {
                next = next_freelist_entry(s, slab, &pos, start, page_limit,
                        freelist_count);
                next = setup_object(s, next);
                set_freepointer(s, cur, next);
                cur = next;
        }
        set_freepointer(s, cur, NULL);

        return true;
}
#else
static inline int init_cache_random_seq(struct kmem_cache *s)
{
        return 0;
}
static inline void init_freelist_randomization(void) { }
static inline bool shuffle_freelist(struct kmem_cache *s, struct slab *slab)
{
        return false;
}
#endif /* CONFIG_SLAB_FREELIST_RANDOM */

static struct slab *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
{
        struct slab *slab;
        struct kmem_cache_order_objects oo = s->oo;
        gfp_t alloc_gfp;
        void *start, *p, *next;
        int idx;
        bool shuffle;

        flags &= gfp_allowed_mask;

        flags |= s->allocflags;

        /*
         * Let the initial higher-order allocation fail under memory pressure
         * so we fall-back to the minimum order allocation.
         */
        alloc_gfp = (flags | __GFP_NOWARN | __GFP_NORETRY) & ~__GFP_NOFAIL;
        if ((alloc_gfp & __GFP_DIRECT_RECLAIM) && oo_order(oo) > oo_order(s->min))
                alloc_gfp = (alloc_gfp | __GFP_NOMEMALLOC) & ~__GFP_RECLAIM;

        slab = alloc_slab_page(alloc_gfp, node, oo);
        if (unlikely(!slab)) {
                oo = s->min;
                alloc_gfp = flags;
                /*
                 * Allocation may have failed due to fragmentation.
                 * Try a lower order alloc if possible
                 */
                slab = alloc_slab_page(alloc_gfp, node, oo);
                if (unlikely(!slab))
                        return NULL;
                stat(s, ORDER_FALLBACK);
        }

        slab->objects = oo_objects(oo);
        slab->inuse = 0;
        slab->frozen = 0;

        account_slab(slab, oo_order(oo), s, flags);

        slab->slab_cache = s;

        kasan_poison_slab(slab);

        start = slab_address(slab);

        setup_slab_debug(s, slab, start);

        shuffle = shuffle_freelist(s, slab);

        if (!shuffle) {
                start = fixup_red_left(s, start);
                start = setup_object(s, start);
                slab->freelist = start;
                for (idx = 0, p = start; idx < slab->objects - 1; idx++) {
                        next = p + s->size;
                        next = setup_object(s, next);
                        set_freepointer(s, p, next);
                        p = next;
                }
                set_freepointer(s, p, NULL);
        }

        return slab;
}

static struct slab *new_slab(struct kmem_cache *s, gfp_t flags, int node)
{
        if (unlikely(flags & GFP_SLAB_BUG_MASK))
                flags = kmalloc_fix_flags(flags);

        WARN_ON_ONCE(s->ctor && (flags & __GFP_ZERO));

        return allocate_slab(s,
                flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
}

static void __free_slab(struct kmem_cache *s, struct slab *slab)
{
        struct folio *folio = slab_folio(slab);
        int order = folio_order(folio);
        int pages = 1 << order;

        if (kmem_cache_debug_flags(s, SLAB_CONSISTENCY_CHECKS)) {
                void *p;

                slab_pad_check(s, slab);
                for_each_object(p, s, slab_address(slab), slab->objects)
                        check_object(s, slab, p, SLUB_RED_INACTIVE);
        }

        __slab_clear_pfmemalloc(slab);
        __folio_clear_slab(folio);
        folio->mapping = NULL;
        if (current->reclaim_state)
                current->reclaim_state->reclaimed_slab += pages;
        unaccount_slab(slab, order, s);
        __free_pages(folio_page(folio, 0), order);
}

static void rcu_free_slab(struct rcu_head *h)
{
        struct slab *slab = container_of(h, struct slab, rcu_head);

        __free_slab(slab->slab_cache, slab);
}

static void free_slab(struct kmem_cache *s, struct slab *slab)
{
        if (unlikely(s->flags & SLAB_TYPESAFE_BY_RCU)) {
                call_rcu(&slab->rcu_head, rcu_free_slab);
        } else
                __free_slab(s, slab);
}

static void discard_slab(struct kmem_cache *s, struct slab *slab)
{
        dec_slabs_node(s, slab_nid(slab), slab->objects);
        free_slab(s, slab);
}

/*
 * Management of partially allocated slabs.
 */
static inline void
__add_partial(struct kmem_cache_node *n, struct slab *slab, int tail)
{
        n->nr_partial++;
        if (tail == DEACTIVATE_TO_TAIL)
                list_add_tail(&slab->slab_list, &n->partial);
        else
                list_add(&slab->slab_list, &n->partial);
}

static inline void add_partial(struct kmem_cache_node *n,
                                struct slab *slab, int tail)
{
        lockdep_assert_held(&n->list_lock);
        __add_partial(n, slab, tail);
}

static inline void remove_partial(struct kmem_cache_node *n,
                                        struct slab *slab)
{
        lockdep_assert_held(&n->list_lock);
        list_del(&slab->slab_list);
        n->nr_partial--;
}

/*
 * Called only for kmem_cache_debug() caches instead of acquire_slab(), with a
 * slab from the n->partial list. Remove only a single object from the slab, do
 * the alloc_debug_processing() checks and leave the slab on the list, or move
 * it to full list if it was the last free object.
 */
static void *alloc_single_from_partial(struct kmem_cache *s,
                struct kmem_cache_node *n, struct slab *slab, int orig_size)
{
        void *object;

        lockdep_assert_held(&n->list_lock);

        object = slab->freelist;
        slab->freelist = get_freepointer(s, object);
        slab->inuse++;

        if (!alloc_debug_processing(s, slab, object, orig_size)) {
                remove_partial(n, slab);
                return NULL;
        }

        if (slab->inuse == slab->objects) {
                remove_partial(n, slab);
                add_full(s, n, slab);
        }

        return object;
}

/*
 * Called only for kmem_cache_debug() caches to allocate from a freshly
 * allocated slab. Allocate a single object instead of whole freelist
 * and put the slab to the partial (or full) list.
 */
static void *alloc_single_from_new_slab(struct kmem_cache *s,
                                        struct slab *slab, int orig_size)
{
        int nid = slab_nid(slab);
        struct kmem_cache_node *n = get_node(s, nid);
        unsigned long flags;
        void *object;


        object = slab->freelist;
        slab->freelist = get_freepointer(s, object);
        slab->inuse = 1;

        if (!alloc_debug_processing(s, slab, object, orig_size))
                /*
                 * It's not really expected that this would fail on a
                 * freshly allocated slab, but a concurrent memory
                 * corruption in theory could cause that.
                 */
                return NULL;

        spin_lock_irqsave(&n->list_lock, flags);

        if (slab->inuse == slab->objects)
                add_full(s, n, slab);
        else
                add_partial(n, slab, DEACTIVATE_TO_HEAD);

        inc_slabs_node(s, nid, slab->objects);
        spin_unlock_irqrestore(&n->list_lock, flags);

        return object;
}

/*
 * Remove slab from the partial list, freeze it and
 * return the pointer to the freelist.
 *
 * Returns a list of objects or NULL if it fails.
 */
static inline void *acquire_slab(struct kmem_cache *s,
                struct kmem_cache_node *n, struct slab *slab,
                int mode)
{
        void *freelist;
        unsigned long counters;
        struct slab new;

        lockdep_assert_held(&n->list_lock);

        /*
         * Zap the freelist and set the frozen bit.
         * The old freelist is the list of objects for the
         * per cpu allocation list.
         */
        freelist = slab->freelist;
        counters = slab->counters;
        new.counters = counters;
        if (mode) {
                new.inuse = slab->objects;
                new.freelist = NULL;
        } else {
                new.freelist = freelist;
        }

        VM_BUG_ON(new.frozen);
        new.frozen = 1;

        if (!__cmpxchg_double_slab(s, slab,
                        freelist, counters,
                        new.freelist, new.counters,
                        "acquire_slab"))
                return NULL;

        remove_partial(n, slab);
        WARN_ON(!freelist);
        return freelist;
}

#ifdef CONFIG_SLUB_CPU_PARTIAL
static void put_cpu_partial(struct kmem_cache *s, struct slab *slab, int drain);
#else
static inline void put_cpu_partial(struct kmem_cache *s, struct slab *slab,
                                   int drain) { }
#endif
static inline bool pfmemalloc_match(struct slab *slab, gfp_t gfpflags);

/*
 * Try to allocate a partial slab from a specific node.
 */
static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n,
                              struct partial_context *pc)
{
        struct slab *slab, *slab2;
        void *object = NULL;
        unsigned long flags;
        unsigned int partial_slabs = 0;

        /*
         * Racy check. If we mistakenly see no partial slabs then we
         * just allocate an empty slab. If we mistakenly try to get a
         * partial slab and there is none available then get_partial()
         * will return NULL.
         */
        if (!n || !n->nr_partial)
                return NULL;

        spin_lock_irqsave(&n->list_lock, flags);
        list_for_each_entry_safe(slab, slab2, &n->partial, slab_list) {
                void *t;

                if (!pfmemalloc_match(slab, pc->flags))
                        continue;

                if (kmem_cache_debug(s)) {
                        object = alloc_single_from_partial(s, n, slab,
                                                        pc->orig_size);
                        if (object)
                                break;
                        continue;
                }

                t = acquire_slab(s, n, slab, object == NULL);
                if (!t)
                        break;

                if (!object) {
                        *pc->slab = slab;
                        stat(s, ALLOC_FROM_PARTIAL);
                        object = t;
                } else {
                        put_cpu_partial(s, slab, 0);
                        stat(s, CPU_PARTIAL_NODE);
                        partial_slabs++;
                }
#ifdef CONFIG_SLUB_CPU_PARTIAL
                if (!kmem_cache_has_cpu_partial(s)
                        || partial_slabs > s->cpu_partial_slabs / 2)
                        break;
#else
                break;
#endif

        }
        spin_unlock_irqrestore(&n->list_lock, flags);
        return object;
}

/*
 * Get a slab from somewhere. Search in increasing NUMA distances.
 */
static void *get_any_partial(struct kmem_cache *s, struct partial_context *pc)
{
#ifdef CONFIG_NUMA
        struct zonelist *zonelist;
        struct zoneref *z;
        struct zone *zone;
        enum zone_type highest_zoneidx = gfp_zone(pc->flags);
        void *object;
        unsigned int cpuset_mems_cookie;

        /*
         * The defrag ratio allows a configuration of the tradeoffs between
         * inter node defragmentation and node local allocations. A lower
         * defrag_ratio increases the tendency to do local allocations
         * instead of attempting to obtain partial slabs from other nodes.
         *
         * If the defrag_ratio is set to 0 then kmalloc() always
         * returns node local objects. If the ratio is higher then kmalloc()
         * may return off node objects because partial slabs are obtained
         * from other nodes and filled up.
         *
         * If /sys/kernel/slab/xx/remote_node_defrag_ratio is set to 100
         * (which makes defrag_ratio = 1000) then every (well almost)
         * allocation will first attempt to defrag slab caches on other nodes.
         * This means scanning over all nodes to look for partial slabs which
         * may be expensive if we do it every time we are trying to find a slab
         * with available objects.
         */
        if (!s->remote_node_defrag_ratio ||
                        get_cycles() % 1024 > s->remote_node_defrag_ratio)
                return NULL;

        do {
                cpuset_mems_cookie = read_mems_allowed_begin();
                zonelist = node_zonelist(mempolicy_slab_node(), pc->flags);
                for_each_zone_zonelist(zone, z, zonelist, highest_zoneidx) {
                        struct kmem_cache_node *n;

                        n = get_node(s, zone_to_nid(zone));

                        if (n && cpuset_zone_allowed(zone, pc->flags) &&
                                        n->nr_partial > s->min_partial) {
                                object = get_partial_node(s, n, pc);
                                if (object) {
                                        /*
                                         * Don't check read_mems_allowed_retry()
                                         * here - if mems_allowed was updated in
                                         * parallel, that was a harmless race
                                         * between allocation and the cpuset
                                         * update
                                         */
                                        return object;
                                }
                        }
                }
        } while (read_mems_allowed_retry(cpuset_mems_cookie));
#endif  /* CONFIG_NUMA */
        return NULL;
}

/*
 * Get a partial slab, lock it and return it.
 */
static void *get_partial(struct kmem_cache *s, int node, struct partial_context *pc)
{
        void *object;
        int searchnode = node;

        if (node == NUMA_NO_NODE)
                searchnode = numa_mem_id();

        object = get_partial_node(s, get_node(s, searchnode), pc);
        if (object || node != NUMA_NO_NODE)
                return object;

        return get_any_partial(s, pc);
}

#ifdef CONFIG_PREEMPTION
/*
 * Calculate the next globally unique transaction for disambiguation
 * during cmpxchg. The transactions start with the cpu number and are then
 * incremented by CONFIG_NR_CPUS.
 */
#define TID_STEP  roundup_pow_of_two(CONFIG_NR_CPUS)
#else
/*
 * No preemption supported therefore also no need to check for
 * different cpus.
 */
#define TID_STEP 1
#endif

static inline unsigned long next_tid(unsigned long tid)
{
        return tid + TID_STEP;
}

#ifdef SLUB_DEBUG_CMPXCHG
static inline unsigned int tid_to_cpu(unsigned long tid)
{
        return tid % TID_STEP;
}

static inline unsigned long tid_to_event(unsigned long tid)
{
        return tid / TID_STEP;
}
#endif

static inline unsigned int init_tid(int cpu)
{
        return cpu;
}

static inline void note_cmpxchg_failure(const char *n,
                const struct kmem_cache *s, unsigned long tid)
{
#ifdef SLUB_DEBUG_CMPXCHG
        unsigned long actual_tid = __this_cpu_read(s->cpu_slab->tid);

        pr_info("%s %s: cmpxchg redo ", n, s->name);

#ifdef CONFIG_PREEMPTION
        if (tid_to_cpu(tid) != tid_to_cpu(actual_tid))
                pr_warn("due to cpu change %d -> %d\n",
                        tid_to_cpu(tid), tid_to_cpu(actual_tid));
        else
#endif
        if (tid_to_event(tid) != tid_to_event(actual_tid))
                pr_warn("due to cpu running other code. Event %ld->%ld\n",
                        tid_to_event(tid), tid_to_event(actual_tid));
        else
                pr_warn("for unknown reason: actual=%lx was=%lx target=%lx\n",
                        actual_tid, tid, next_tid(tid));
#endif
        stat(s, CMPXCHG_DOUBLE_CPU_FAIL);
}

static void init_kmem_cache_cpus(struct kmem_cache *s)
{
        int cpu;
        struct kmem_cache_cpu *c;

        for_each_possible_cpu(cpu) {
                c = per_cpu_ptr(s->cpu_slab, cpu);
                local_lock_init(&c->lock);
                c->tid = init_tid(cpu);
        }
}

/*
 * Finishes removing the cpu slab. Merges cpu's freelist with slab's freelist,
 * unfreezes the slabs and puts it on the proper list.
 * Assumes the slab has been already safely taken away from kmem_cache_cpu
 * by the caller.
 */
static void deactivate_slab(struct kmem_cache *s, struct slab *slab,
                            void *freelist)
{
        enum slab_modes { M_NONE, M_PARTIAL, M_FULL, M_FREE, M_FULL_NOLIST };
        struct kmem_cache_node *n = get_node(s, slab_nid(slab));
        int free_delta = 0;
        enum slab_modes mode = M_NONE;
        void *nextfree, *freelist_iter, *freelist_tail;
        int tail = DEACTIVATE_TO_HEAD;
        unsigned long flags = 0;
        struct slab new;
        struct slab old;

        if (slab->freelist) {
                stat(s, DEACTIVATE_REMOTE_FREES);
                tail = DEACTIVATE_TO_TAIL;
        }

        /*
         * Stage one: Count the objects on cpu's freelist as free_delta and
         * remember the last object in freelist_tail for later splicing.
         */
        freelist_tail = NULL;
        freelist_iter = freelist;
        while (freelist_iter) {
                nextfree = get_freepointer(s, freelist_iter);

                /*
                 * If 'nextfree' is invalid, it is possible that the object at
                 * 'freelist_iter' is already corrupted.  So isolate all objects
                 * starting at 'freelist_iter' by skipping them.
                 */
                if (freelist_corrupted(s, slab, &freelist_iter, nextfree))
                        break;

                freelist_tail = freelist_iter;
                free_delta++;

                freelist_iter = nextfree;
        }

        /*
         * Stage two: Unfreeze the slab while splicing the per-cpu
         * freelist to the head of slab's freelist.
         *
         * Ensure that the slab is unfrozen while the list presence
         * reflects the actual number of objects during unfreeze.
         *
         * We first perform cmpxchg holding lock and insert to list
         * when it succeed. If there is mismatch then the slab is not
         * unfrozen and number of objects in the slab may have changed.
         * Then release lock and retry cmpxchg again.
         */
redo:

        old.freelist = READ_ONCE(slab->freelist);
        old.counters = READ_ONCE(slab->counters);
        VM_BUG_ON(!old.frozen);

        /* Determine target state of the slab */
        new.counters = old.counters;
        if (freelist_tail) {
                new.inuse -= free_delta;
                set_freepointer(s, freelist_tail, old.freelist);
                new.freelist = freelist;
        } else
                new.freelist = old.freelist;

        new.frozen = 0;

        if (!new.inuse && n->nr_partial >= s->min_partial) {
                mode = M_FREE;
        } else if (new.freelist) {
                mode = M_PARTIAL;
                /*
                 * Taking the spinlock removes the possibility that
                 * acquire_slab() will see a slab that is frozen
                 */
                spin_lock_irqsave(&n->list_lock, flags);
        } else if (kmem_cache_debug_flags(s, SLAB_STORE_USER)) {
                mode = M_FULL;
                /*
                 * This also ensures that the scanning of full
                 * slabs from diagnostic functions will not see
                 * any frozen slabs.
                 */
                spin_lock_irqsave(&n->list_lock, flags);
        } else {
                mode = M_FULL_NOLIST;
        }


        if (!cmpxchg_double_slab(s, slab,
                                old.freelist, old.counters,
                                new.freelist, new.counters,
                                "unfreezing slab")) {
                if (mode == M_PARTIAL || mode == M_FULL)
                        spin_unlock_irqrestore(&n->list_lock, flags);
                goto redo;
        }


        if (mode == M_PARTIAL) {
                add_partial(n, slab, tail);
                spin_unlock_irqrestore(&n->list_lock, flags);
                stat(s, tail);
        } else if (mode == M_FREE) {
                stat(s, DEACTIVATE_EMPTY);
                discard_slab(s, slab);
                stat(s, FREE_SLAB);
        } else if (mode == M_FULL) {
                add_full(s, n, slab);
                spin_unlock_irqrestore(&n->list_lock, flags);
                stat(s, DEACTIVATE_FULL);
        } else if (mode == M_FULL_NOLIST) {
                stat(s, DEACTIVATE_FULL);
        }
}

#ifdef CONFIG_SLUB_CPU_PARTIAL
static void __unfreeze_partials(struct kmem_cache *s, struct slab *partial_slab)
{
        struct kmem_cache_node *n = NULL, *n2 = NULL;
        struct slab *slab, *slab_to_discard = NULL;
        unsigned long flags = 0;

        while (partial_slab) {
                struct slab new;
                struct slab old;

                slab = partial_slab;
                partial_slab = slab->next;

                n2 = get_node(s, slab_nid(slab));
                if (n != n2) {
                        if (n)
                                spin_unlock_irqrestore(&n->list_lock, flags);

                        n = n2;
                        spin_lock_irqsave(&n->list_lock, flags);
                }

                do {

                        old.freelist = slab->freelist;
                        old.counters = slab->counters;
                        VM_BUG_ON(!old.frozen);

                        new.counters = old.counters;
                        new.freelist = old.freelist;

                        new.frozen = 0;

                } while (!__cmpxchg_double_slab(s, slab,
                                old.freelist, old.counters,
                                new.freelist, new.counters,
                                "unfreezing slab"));

                if (unlikely(!new.inuse && n->nr_partial >= s->min_partial)) {
                        slab->next = slab_to_discard;
                        slab_to_discard = slab;
                } else {
                        add_partial(n, slab, DEACTIVATE_TO_TAIL);
                        stat(s, FREE_ADD_PARTIAL);
                }
        }

        if (n)
                spin_unlock_irqrestore(&n->list_lock, flags);

        while (slab_to_discard) {
                slab = slab_to_discard;
                slab_to_discard = slab_to_discard->next;

                stat(s, DEACTIVATE_EMPTY);
                discard_slab(s, slab);
                stat(s, FREE_SLAB);
        }
}

/*
 * Unfreeze all the cpu partial slabs.
 */
static void unfreeze_partials(struct kmem_cache *s)
{
        struct slab *partial_slab;
        unsigned long flags;

        local_lock_irqsave(&s->cpu_slab->lock, flags);
        partial_slab = this_cpu_read(s->cpu_slab->partial);
        this_cpu_write(s->cpu_slab->partial, NULL);
        local_unlock_irqrestore(&s->cpu_slab->lock, flags);

        if (partial_slab)
                __unfreeze_partials(s, partial_slab);
}

static void unfreeze_partials_cpu(struct kmem_cache *s,
                                  struct kmem_cache_cpu *c)
{
        struct slab *partial_slab;

        partial_slab = slub_percpu_partial(c);
        c->partial = NULL;

        if (partial_slab)
                __unfreeze_partials(s, partial_slab);
}

/*
 * Put a slab that was just frozen (in __slab_free|get_partial_node) into a
 * partial slab slot if available.
 *
 * If we did not find a slot then simply move all the partials to the
 * per node partial list.
 */
static void put_cpu_partial(struct kmem_cache *s, struct slab *slab, int drain)
{
        struct slab *oldslab;
        struct slab *slab_to_unfreeze = NULL;
        unsigned long flags;
        int slabs = 0;

        local_lock_irqsave(&s->cpu_slab->lock, flags);

        oldslab = this_cpu_read(s->cpu_slab->partial);

        if (oldslab) {
                if (drain && oldslab->slabs >= s->cpu_partial_slabs) {
                        /*
                         * Partial array is full. Move the existing set to the
                         * per node partial list. Postpone the actual unfreezing
                         * outside of the critical section.
                         */
                        slab_to_unfreeze = oldslab;
                        oldslab = NULL;
                } else {
                        slabs = oldslab->slabs;
                }
        }

        slabs++;

        slab->slabs = slabs;
        slab->next = oldslab;

        this_cpu_write(s->cpu_slab->partial, slab);

        local_unlock_irqrestore(&s->cpu_slab->lock, flags);

        if (slab_to_unfreeze) {
                __unfreeze_partials(s, slab_to_unfreeze);
                stat(s, CPU_PARTIAL_DRAIN);
        }
}

#else   /* CONFIG_SLUB_CPU_PARTIAL */

static inline void unfreeze_partials(struct kmem_cache *s) { }
static inline void unfreeze_partials_cpu(struct kmem_cache *s,
                                  struct kmem_cache_cpu *c) { }

#endif  /* CONFIG_SLUB_CPU_PARTIAL */

static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
{
        unsigned long flags;
        struct slab *slab;
        void *freelist;

        local_lock_irqsave(&s->cpu_slab->lock, flags);

        slab = c->slab;
        freelist = c->freelist;

        c->slab = NULL;
        c->freelist = NULL;
        c->tid = next_tid(c->tid);

        local_unlock_irqrestore(&s->cpu_slab->lock, flags);

        if (slab) {
                deactivate_slab(s, slab, freelist);
                stat(s, CPUSLAB_FLUSH);
        }
}

static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu)
{
        struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
        void *freelist = c->freelist;
        struct slab *slab = c->slab;

        c->slab = NULL;
        c->freelist = NULL;
        c->tid = next_tid(c->tid);

        if (slab) {
                deactivate_slab(s, slab, freelist);
                stat(s, CPUSLAB_FLUSH);
        }

        unfreeze_partials_cpu(s, c);
}

struct slub_flush_work {
        struct work_struct work;
        struct kmem_cache *s;
        bool skip;
};

/*
 * Flush cpu slab.
 *
 * Called from CPU work handler with migration disabled.
 */
static void flush_cpu_slab(struct work_struct *w)
{
        struct kmem_cache *s;
        struct kmem_cache_cpu *c;
        struct slub_flush_work *sfw;

        sfw = container_of(w, struct slub_flush_work, work);

        s = sfw->s;
        c = this_cpu_ptr(s->cpu_slab);

        if (c->slab)
                flush_slab(s, c);

        unfreeze_partials(s);
}

static bool has_cpu_slab(int cpu, struct kmem_cache *s)
{
        struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);

        return c->slab || slub_percpu_partial(c);
}

static DEFINE_MUTEX(flush_lock);
static DEFINE_PER_CPU(struct slub_flush_work, slub_flush);

static void flush_all_cpus_locked(struct kmem_cache *s)
{
        struct slub_flush_work *sfw;
        unsigned int cpu;

        lockdep_assert_cpus_held();
        mutex_lock(&flush_lock);

        for_each_online_cpu(cpu) {
                sfw = &per_cpu(slub_flush, cpu);
                if (!has_cpu_slab(cpu, s)) {
                        sfw->skip = true;
                        continue;
                }
                INIT_WORK(&sfw->work, flush_cpu_slab);
                sfw->skip = false;
                sfw->s = s;
                queue_work_on(cpu, flushwq, &sfw->work);
        }

        for_each_online_cpu(cpu) {
                sfw = &per_cpu(slub_flush, cpu);
                if (sfw->skip)
                        continue;
                flush_work(&sfw->work);
        }

        mutex_unlock(&flush_lock);
}

static void flush_all(struct kmem_cache *s)
{
        cpus_read_lock();
        flush_all_cpus_locked(s);
        cpus_read_unlock();
}

/*
 * Use the cpu notifier to insure that the cpu slabs are flushed when
 * necessary.
 */
static int slub_cpu_dead(unsigned int cpu)
{
        struct kmem_cache *s;

        mutex_lock(&slab_mutex);
        list_for_each_entry(s, &slab_caches, list)
                __flush_cpu_slab(s, cpu);
        mutex_unlock(&slab_mutex);
        return 0;
}

/*
 * Check if the objects in a per cpu structure fit numa
 * locality expectations.
 */
static inline int node_match(struct slab *slab, int node)
{
#ifdef CONFIG_NUMA
        if (node != NUMA_NO_NODE && slab_nid(slab) != node)
                return 0;
#endif
        return 1;
}

#ifdef CONFIG_SLUB_DEBUG
static int count_free(struct slab *slab)
{
        return slab->objects - slab->inuse;
}

static inline unsigned long node_nr_objs(struct kmem_cache_node *n)
{
        return atomic_long_read(&n->total_objects);
}

/* Supports checking bulk free of a constructed freelist */
static noinline void free_debug_processing(
        struct kmem_cache *s, struct slab *slab,
        void *head, void *tail, int bulk_cnt,
        unsigned long addr)
{
        struct kmem_cache_node *n = get_node(s, slab_nid(slab));
        struct slab *slab_free = NULL;
        void *object = head;
        int cnt = 0;
        unsigned long flags;
        bool checks_ok = false;
        depot_stack_handle_t handle = 0;

        if (s->flags & SLAB_STORE_USER)
                handle = set_track_prepare();

        spin_lock_irqsave(&n->list_lock, flags);

        if (s->flags & SLAB_CONSISTENCY_CHECKS) {
                if (!check_slab(s, slab))
                        goto out;
        }

        if (slab->inuse < bulk_cnt) {
                slab_err(s, slab, "Slab has %d allocated objects but %d are to be freed\n",
                         slab->inuse, bulk_cnt);
                goto out;
        }

next_object:

        if (++cnt > bulk_cnt)
                goto out_cnt;

        if (s->flags & SLAB_CONSISTENCY_CHECKS) {
                if (!free_consistency_checks(s, slab, object, addr))
                        goto out;
        }

        if (s->flags & SLAB_STORE_USER)
                set_track_update(s, object, TRACK_FREE, addr, handle);
        trace(s, slab, object, 0);
        /* Freepointer not overwritten by init_object(), SLAB_POISON moved it */
        init_object(s, object, SLUB_RED_INACTIVE);

        /* Reached end of constructed freelist yet? */
        if (object != tail) {
                object = get_freepointer(s, object);
                goto next_object;
        }
        checks_ok = true;

out_cnt:
        if (cnt != bulk_cnt)
                slab_err(s, slab, "Bulk free expected %d objects but found %d\n",
                         bulk_cnt, cnt);

out:
        if (checks_ok) {
                void *prior = slab->freelist;

                /* Perform the actual freeing while we still hold the locks */
                slab->inuse -= cnt;
                set_freepointer(s, tail, prior);
                slab->freelist = head;

                /*
                 * If the slab is empty, and node's partial list is full,
                 * it should be discarded anyway no matter it's on full or
                 * partial list.
                 */
                if (slab->inuse == 0 && n->nr_partial >= s->min_partial)
                        slab_free = slab;

                if (!prior) {
                        /* was on full list */
                        remove_full(s, n, slab);
                        if (!slab_free) {
                                add_partial(n, slab, DEACTIVATE_TO_TAIL);
                                stat(s, FREE_ADD_PARTIAL);
                        }
                } else if (slab_free) {
                        remove_partial(n, slab);
                        stat(s, FREE_REMOVE_PARTIAL);
                }
        }

        if (slab_free) {
                /*
                 * Update the counters while still holding n->list_lock to
                 * prevent spurious validation warnings
                 */
                dec_slabs_node(s, slab_nid(slab_free), slab_free->objects);
        }

        spin_unlock_irqrestore(&n->list_lock, flags);

        if (!checks_ok)
                slab_fix(s, "Object at 0x%p not freed", object);

        if (slab_free) {
                stat(s, FREE_SLAB);
                free_slab(s, slab_free);
        }
}
#endif /* CONFIG_SLUB_DEBUG */

#if defined(CONFIG_SLUB_DEBUG) || defined(CONFIG_SYSFS)
static unsigned long count_partial(struct kmem_cache_node *n,
                                        int (*get_count)(struct slab *))
{
        unsigned long flags;
        unsigned long x = 0;
        struct slab *slab;

        spin_lock_irqsave(&n->list_lock, flags);
        list_for_each_entry(slab, &n->partial, slab_list)
                x += get_count(slab);
        spin_unlock_irqrestore(&n->list_lock, flags);
        return x;
}
#endif /* CONFIG_SLUB_DEBUG || CONFIG_SYSFS */

static noinline void
slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid)
{
#ifdef CONFIG_SLUB_DEBUG
        static DEFINE_RATELIMIT_STATE(slub_oom_rs, DEFAULT_RATELIMIT_INTERVAL,
                                      DEFAULT_RATELIMIT_BURST);
        int node;
        struct kmem_cache_node *n;

        if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slub_oom_rs))
                return;

        pr_warn("SLUB: Unable to allocate memory on node %d, gfp=%#x(%pGg)\n",
                nid, gfpflags, &gfpflags);
        pr_warn("  cache: %s, object size: %u, buffer size: %u, default order: %u, min order: %u\n",
                s->name, s->object_size, s->size, oo_order(s->oo),
                oo_order(s->min));

        if (oo_order(s->min) > get_order(s->object_size))
                pr_warn("  %s debugging increased min order, use slub_debug=O to disable.\n",
                        s->name);

        for_each_kmem_cache_node(s, node, n) {
                unsigned long nr_slabs;
                unsigned long nr_objs;
                unsigned long nr_free;

                nr_free  = count_partial(n, count_free);
                nr_slabs = node_nr_slabs(n);
                nr_objs  = node_nr_objs(n);

                pr_warn("  node %d: slabs: %ld, objs: %ld, free: %ld\n",
                        node, nr_slabs, nr_objs, nr_free);
        }
#endif
}

static inline bool pfmemalloc_match(struct slab *slab, gfp_t gfpflags)
{
        if (unlikely(slab_test_pfmemalloc(slab)))
                return gfp_pfmemalloc_allowed(gfpflags);

        return true;
}

/*
 * Check the slab->freelist and either transfer the freelist to the
 * per cpu freelist or deactivate the slab.
 *
 * The slab is still frozen if the return value is not NULL.
 *
 * If this function returns NULL then the slab has been unfrozen.
 */
static inline void *get_freelist(struct kmem_cache *s, struct slab *slab)
{
        struct slab new;
        unsigned long counters;
        void *freelist;

        lockdep_assert_held(this_cpu_ptr(&s->cpu_slab->lock));

        do {
                freelist = slab->freelist;
                counters = slab->counters;

                new.counters = counters;
                VM_BUG_ON(!new.frozen);

                new.inuse = slab->objects;
                new.frozen = freelist != NULL;

        } while (!__cmpxchg_double_slab(s, slab,
                freelist, counters,
                NULL, new.counters,
                "get_freelist"));

        return freelist;
}

/*
 * Slow path. The lockless freelist is empty or we need to perform
 * debugging duties.
 *
 * Processing is still very fast if new objects have been freed to the
 * regular freelist. In that case we simply take over the regular freelist
 * as the lockless freelist and zap the regular freelist.
 *
 * If that is not working then we fall back to the partial lists. We take the
 * first element of the freelist as the object to allocate now and move the
 * rest of the freelist to the lockless freelist.
 *
 * And if we were unable to get a new slab from the partial slab lists then
 * we need to allocate a new slab. This is the slowest path since it involves
 * a call to the page allocator and the setup of a new slab.
 *
 * Version of __slab_alloc to use when we know that preemption is
 * already disabled (which is the case for bulk allocation).
 */
static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
                          unsigned long addr, struct kmem_cache_cpu *c, unsigned int orig_size)
{
        void *freelist;
        struct slab *slab;
        unsigned long flags;
        struct partial_context pc;

        stat(s, ALLOC_SLOWPATH);

reread_slab:

        slab = READ_ONCE(c->slab);
        if (!slab) {
                /*
                 * if the node is not online or has no normal memory, just
                 * ignore the node constraint
                 */
                if (unlikely(node != NUMA_NO_NODE &&
                             !node_isset(node, slab_nodes)))
                        node = NUMA_NO_NODE;
                goto new_slab;
        }
redo:

        if (unlikely(!node_match(slab, node))) {
                /*
                 * same as above but node_match() being false already
                 * implies node != NUMA_NO_NODE
                 */
                if (!node_isset(node, slab_nodes)) {
                        node = NUMA_NO_NODE;
                } else {
                        stat(s, ALLOC_NODE_MISMATCH);
                        goto deactivate_slab;
                }
        }

        /*
         * By rights, we should be searching for a slab page that was
         * PFMEMALLOC but right now, we are losing the pfmemalloc
         * information when the page leaves the per-cpu allocator
         */
        if (unlikely(!pfmemalloc_match(slab, gfpflags)))
                goto deactivate_slab;

        /* must check again c->slab in case we got preempted and it changed */
        local_lock_irqsave(&s->cpu_slab->lock, flags);
        if (unlikely(slab != c->slab)) {
                local_unlock_irqrestore(&s->cpu_slab->lock, flags);
                goto reread_slab;
        }
        freelist = c->freelist;
        if (freelist)
                goto load_freelist;

        freelist = get_freelist(s, slab);

        if (!freelist) {
                c->slab = NULL;
                c->tid = next_tid(c->tid);
                local_unlock_irqrestore(&s->cpu_slab->lock, flags);
                stat(s, DEACTIVATE_BYPASS);
                goto new_slab;
        }

        stat(s, ALLOC_REFILL);

load_freelist:

        lockdep_assert_held(this_cpu_ptr(&s->cpu_slab->lock));

        /*
         * freelist is pointing to the list of objects to be used.
         * slab is pointing to the slab from which the objects are obtained.
         * That slab must be frozen for per cpu allocations to work.
         */
        VM_BUG_ON(!c->slab->frozen);
        c->freelist = get_freepointer(s, freelist);
        c->tid = next_tid(c->tid);
        local_unlock_irqrestore(&s->cpu_slab->lock, flags);
        return freelist;

deactivate_slab:

        local_lock_irqsave(&s->cpu_slab->lock, flags);
        if (slab != c->slab) {
                local_unlock_irqrestore(&s->cpu_slab->lock, flags);
                goto reread_slab;
        }
        freelist = c->freelist;
        c->slab = NULL;
        c->freelist = NULL;
        c->tid = next_tid(c->tid);
        local_unlock_irqrestore(&s->cpu_slab->lock, flags);
        deactivate_slab(s, slab, freelist);

new_slab:

        if (slub_percpu_partial(c)) {
                local_lock_irqsave(&s->cpu_slab->lock, flags);
                if (unlikely(c->slab)) {
                        local_unlock_irqrestore(&s->cpu_slab->lock, flags);
                        goto reread_slab;
                }
                if (unlikely(!slub_percpu_partial(c))) {
                        local_unlock_irqrestore(&s->cpu_slab->lock, flags);
                        /* we were preempted and partial list got empty */
                        goto new_objects;
                }

                slab = c->slab = slub_percpu_partial(c);
                slub_set_percpu_partial(c, slab);
                local_unlock_irqrestore(&s->cpu_slab->lock, flags);
                stat(s, CPU_PARTIAL_ALLOC);
                goto redo;
        }

new_objects:

        pc.flags = gfpflags;
        pc.slab = &slab;
        pc.orig_size = orig_size;
        freelist = get_partial(s, node, &pc);
        if (freelist)
                goto check_new_slab;

        slub_put_cpu_ptr(s->cpu_slab);
        slab = new_slab(s, gfpflags, node);
        c = slub_get_cpu_ptr(s->cpu_slab);

        if (unlikely(!slab)) {
                slab_out_of_memory(s, gfpflags, node);
                return NULL;
        }

        stat(s, ALLOC_SLAB);

        if (kmem_cache_debug(s)) {
                freelist = alloc_single_from_new_slab(s, slab, orig_size);

                if (unlikely(!freelist))
                        goto new_objects;

                if (s->flags & SLAB_STORE_USER)
                        set_track(s, freelist, TRACK_ALLOC, addr);

                return freelist;
        }

        /*
         * No other reference to the slab yet so we can
         * muck around with it freely without cmpxchg
         */
        freelist = slab->freelist;
        slab->freelist = NULL;
        slab->inuse = slab->objects;
        slab->frozen = 1;

        inc_slabs_node(s, slab_nid(slab), slab->objects);

check_new_slab:

        if (kmem_cache_debug(s)) {
                /*
                 * For debug caches here we had to go through
                 * alloc_single_from_partial() so just store the tracking info
                 * and return the object
                 */
                if (s->flags & SLAB_STORE_USER)
                        set_track(s, freelist, TRACK_ALLOC, addr);

                return freelist;
        }

        if (unlikely(!pfmemalloc_match(slab, gfpflags))) {
                /*
                 * For !pfmemalloc_match() case we don't load freelist so that
                 * we don't make further mismatched allocations easier.
                 */
                deactivate_slab(s, slab, get_freepointer(s, freelist));
                return freelist;
        }

retry_load_slab:

        local_lock_irqsave(&s->cpu_slab->lock, flags);
        if (unlikely(c->slab)) {
                void *flush_freelist = c->freelist;
                struct slab *flush_slab = c->slab;

                c->slab = NULL;
                c->freelist = NULL;
                c->tid = next_tid(c->tid);

                local_unlock_irqrestore(&s->cpu_slab->lock, flags);

                deactivate_slab(s, flush_slab, flush_freelist);

                stat(s, CPUSLAB_FLUSH);

                goto retry_load_slab;
        }
        c->slab = slab;

        goto load_freelist;
}

/*
 * A wrapper for ___slab_alloc() for contexts where preemption is not yet
 * disabled. Compensates for possible cpu changes by refetching the per cpu area
 * pointer.
 */
static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
                          unsigned long addr, struct kmem_cache_cpu *c, unsigned int orig_size)
{
        void *p;

#ifdef CONFIG_PREEMPT_COUNT
        /*
         * We may have been preempted and rescheduled on a different
         * cpu before disabling preemption. Need to reload cpu area
         * pointer.
         */
        c = slub_get_cpu_ptr(s->cpu_slab);
#endif

        p = ___slab_alloc(s, gfpflags, node, addr, c, orig_size);
#ifdef CONFIG_PREEMPT_COUNT
        slub_put_cpu_ptr(s->cpu_slab);
#endif
        return p;
}

/*
 * If the object has been wiped upon free, make sure it's fully initialized by
 * zeroing out freelist pointer.
 */
static __always_inline void maybe_wipe_obj_freeptr(struct kmem_cache *s,
                                                   void *obj)
{
        if (unlikely(slab_want_init_on_free(s)) && obj)
                memset((void *)((char *)kasan_reset_tag(obj) + s->offset),
                        0, sizeof(void *));
}

/*
 * Inlined fastpath so that allocation functions (kmalloc, kmem_cache_alloc)
 * have the fastpath folded into their functions. So no function call
 * overhead for requests that can be satisfied on the fastpath.
 *
 * The fastpath works by first checking if the lockless freelist can be used.
 * If not then __slab_alloc is called for slow processing.
 *
 * Otherwise we can simply pick the next object from the lockless free list.
 */
static __always_inline void *slab_alloc_node(struct kmem_cache *s, struct list_lru *lru,
                gfp_t gfpflags, int node, unsigned long addr, size_t orig_size)
{
        void *object;
        struct kmem_cache_cpu *c;
        struct slab *slab;
        unsigned long tid;
        struct obj_cgroup *objcg = NULL;
        bool init = false;

        s = slab_pre_alloc_hook(s, lru, &objcg, 1, gfpflags);
        if (!s)
                return NULL;

        object = kfence_alloc(s, orig_size, gfpflags);
        if (unlikely(object))
                goto out;

redo:
        /*
         * Must read kmem_cache cpu data via this cpu ptr. Preemption is
         * enabled. We may switch back and forth between cpus while
         * reading from one cpu area. That does not matter as long
         * as we end up on the original cpu again when doing the cmpxchg.
         *
         * We must guarantee that tid and kmem_cache_cpu are retrieved on the
         * same cpu. We read first the kmem_cache_cpu pointer and use it to read
         * the tid. If we are preempted and switched to another cpu between the
         * two reads, it's OK as the two are still associated with the same cpu
         * and cmpxchg later will validate the cpu.
         */
        c = raw_cpu_ptr(s->cpu_slab);
        tid = READ_ONCE(c->tid);

        /*
         * Irqless object alloc/free algorithm used here depends on sequence
         * of fetching cpu_slab's data. tid should be fetched before anything
         * on c to guarantee that object and slab associated with previous tid
         * won't be used with current tid. If we fetch tid first, object and
         * slab could be one associated with next tid and our alloc/free
         * request will be failed. In this case, we will retry. So, no problem.
         */
        barrier();

        /*
         * The transaction ids are globally unique per cpu and per operation on
         * a per cpu queue. Thus they can be guarantee that the cmpxchg_double
         * occurs on the right processor and that there was no operation on the
         * linked list in between.
         */

        object = c->freelist;
        slab = c->slab;

        if (!USE_LOCKLESS_FAST_PATH() ||
            unlikely(!object || !slab || !node_match(slab, node))) {
                object = __slab_alloc(s, gfpflags, node, addr, c, orig_size);
        } else {
                void *next_object = get_freepointer_safe(s, object);

                /*
                 * The cmpxchg will only match if there was no additional
                 * operation and if we are on the right processor.
                 *
                 * The cmpxchg does the following atomically (without lock
                 * semantics!)
                 * 1. Relocate first pointer to the current per cpu area.
                 * 2. Verify that tid and freelist have not been changed
                 * 3. If they were not changed replace tid and freelist
                 *
                 * Since this is without lock semantics the protection is only
                 * against code executing on this cpu *not* from access by
                 * other cpus.
                 */
                if (unlikely(!this_cpu_cmpxchg_double(
                                s->cpu_slab->freelist, s->cpu_slab->tid,
                                object, tid,
                                next_object, next_tid(tid)))) {

                        note_cmpxchg_failure("slab_alloc", s, tid);
                        goto redo;
                }
                prefetch_freepointer(s, next_object);
                stat(s, ALLOC_FASTPATH);
        }

        maybe_wipe_obj_freeptr(s, object);
        init = slab_want_init_on_alloc(gfpflags, s);

out:
        slab_post_alloc_hook(s, objcg, gfpflags, 1, &object, init);

        return object;
}

static __always_inline void *slab_alloc(struct kmem_cache *s, struct list_lru *lru,
                gfp_t gfpflags, unsigned long addr, size_t orig_size)
{
        return slab_alloc_node(s, lru, gfpflags, NUMA_NO_NODE, addr, orig_size);
}

static __always_inline
void *__kmem_cache_alloc_lru(struct kmem_cache *s, struct list_lru *lru,
                             gfp_t gfpflags)
{
        void *ret = slab_alloc(s, lru, gfpflags, _RET_IP_, s->object_size);

        trace_kmem_cache_alloc(_RET_IP_, ret, s, gfpflags, NUMA_NO_NODE);

        return ret;
}

void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags)
{
        return __kmem_cache_alloc_lru(s, NULL, gfpflags);
}
EXPORT_SYMBOL(kmem_cache_alloc);

void *kmem_cache_alloc_lru(struct kmem_cache *s, struct list_lru *lru,
                           gfp_t gfpflags)
{
        return __kmem_cache_alloc_lru(s, lru, gfpflags);
}
EXPORT_SYMBOL(kmem_cache_alloc_lru);

void *__kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags,
                              int node, size_t orig_size,
                              unsigned long caller)
{
        return slab_alloc_node(s, NULL, gfpflags, node,
                               caller, orig_size);
}

void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node)
{
        void *ret = slab_alloc_node(s, NULL, gfpflags, node, _RET_IP_, s->object_size);

        trace_kmem_cache_alloc(_RET_IP_, ret, s, gfpflags, node);

        return ret;
}
EXPORT_SYMBOL(kmem_cache_alloc_node);

/*
 * Slow path handling. This may still be called frequently since objects
 * have a longer lifetime than the cpu slabs in most processing loads.
 *
 * So we still attempt to reduce cache line usage. Just take the slab
 * lock and free the item. If there is no additional partial slab
 * handling required then we can return immediately.
 */
static void __slab_free(struct kmem_cache *s, struct slab *slab,
                        void *head, void *tail, int cnt,
                        unsigned long addr)

{
        void *prior;
        int was_frozen;
        struct slab new;
        unsigned long counters;
        struct kmem_cache_node *n = NULL;
        unsigned long flags;

        stat(s, FREE_SLOWPATH);

        if (kfence_free(head))
                return;

        if (kmem_cache_debug(s)) {
                free_debug_processing(s, slab, head, tail, cnt, addr);
                return;
        }

        do {
                if (unlikely(n)) {
                        spin_unlock_irqrestore(&n->list_lock, flags);
                        n = NULL;
                }
                prior = slab->freelist;
                counters = slab->counters;
                set_freepointer(s, tail, prior);
                new.counters = counters;
                was_frozen = new.frozen;
                new.inuse -= cnt;
                if ((!new.inuse || !prior) && !was_frozen) {

                        if (kmem_cache_has_cpu_partial(s) && !prior) {

                                /*
                                 * Slab was on no list before and will be
                                 * partially empty
                                 * We can defer the list move and instead
                                 * freeze it.
                                 */
                                new.frozen = 1;

                        } else { /* Needs to be taken off a list */

                                n = get_node(s, slab_nid(slab));
                                /*
                                 * Speculatively acquire the list_lock.
                                 * If the cmpxchg does not succeed then we may
                                 * drop the list_lock without any processing.
                                 *
                                 * Otherwise the list_lock will synchronize with
                                 * other processors updating the list of slabs.
                                 */
                                spin_lock_irqsave(&n->list_lock, flags);

                        }
                }

        } while (!cmpxchg_double_slab(s, slab,
                prior, counters,
                head, new.counters,
                "__slab_free"));

        if (likely(!n)) {

                if (likely(was_frozen)) {
                        /*
                         * The list lock was not taken therefore no list
                         * activity can be necessary.
                         */
                        stat(s, FREE_FROZEN);
                } else if (new.frozen) {
                        /*
                         * If we just froze the slab then put it onto the
                         * per cpu partial list.
                         */
                        put_cpu_partial(s, slab, 1);
                        stat(s, CPU_PARTIAL_FREE);
                }

                return;
        }

        if (unlikely(!new.inuse && n->nr_partial >= s->min_partial))
                goto slab_empty;

        /*
         * Objects left in the slab. If it was not on the partial list before
         * then add it.
         */
        if (!kmem_cache_has_cpu_partial(s) && unlikely(!prior)) {
                remove_full(s, n, slab);
                add_partial(n, slab, DEACTIVATE_TO_TAIL);
                stat(s, FREE_ADD_PARTIAL);
        }
        spin_unlock_irqrestore(&n->list_lock, flags);
        return;

slab_empty:
        if (prior) {
                /*
                 * Slab on the partial list.
                 */
                remove_partial(n, slab);
                stat(s, FREE_REMOVE_PARTIAL);
        } else {
                /* Slab must be on the full list */
                remove_full(s, n, slab);
        }

        spin_unlock_irqrestore(&n->list_lock, flags);
        stat(s, FREE_SLAB);
        discard_slab(s, slab);
}

/*
 * Fastpath with forced inlining to produce a kfree and kmem_cache_free that
 * can perform fastpath freeing without additional function calls.
 *
 * The fastpath is only possible if we are freeing to the current cpu slab
 * of this processor. This typically the case if we have just allocated
 * the item before.
 *
 * If fastpath is not possible then fall back to __slab_free where we deal
 * with all sorts of special processing.
 *
 * Bulk free of a freelist with several objects (all pointing to the
 * same slab) possible by specifying head and tail ptr, plus objects
 * count (cnt). Bulk free indicated by tail pointer being set.
 */
static __always_inline void do_slab_free(struct kmem_cache *s,
                                struct slab *slab, void *head, void *tail,
                                int cnt, unsigned long addr)
{
        void *tail_obj = tail ? : head;
        struct kmem_cache_cpu *c;
        unsigned long tid;
        void **freelist;

redo:
        /*
         * Determine the currently cpus per cpu slab.
         * The cpu may change afterward. However that does not matter since
         * data is retrieved via this pointer. If we are on the same cpu
         * during the cmpxchg then the free will succeed.
         */
        c = raw_cpu_ptr(s->cpu_slab);
        tid = READ_ONCE(c->tid);

        /* Same with comment on barrier() in slab_alloc_node() */
        barrier();

        if (unlikely(slab != c->slab)) {
                __slab_free(s, slab, head, tail_obj, cnt, addr);
                return;
        }

        if (USE_LOCKLESS_FAST_PATH()) {
                freelist = READ_ONCE(c->freelist);

                set_freepointer(s, tail_obj, freelist);

                if (unlikely(!this_cpu_cmpxchg_double(
                                s->cpu_slab->freelist, s->cpu_slab->tid,
                                freelist, tid,
                                head, next_tid(tid)))) {

                        note_cmpxchg_failure("slab_free", s, tid);
                        goto redo;
                }
        } else {
                /* Update the free list under the local lock */
                local_lock(&s->cpu_slab->lock);
                c = this_cpu_ptr(s->cpu_slab);
                if (unlikely(slab != c->slab)) {
                        local_unlock(&s->cpu_slab->lock);
                        goto redo;
                }
                tid = c->tid;
                freelist = c->freelist;

                set_freepointer(s, tail_obj, freelist);
                c->freelist = head;
                c->tid = next_tid(tid);

                local_unlock(&s->cpu_slab->lock);
        }
        stat(s, FREE_FASTPATH);
}

static __always_inline void slab_free(struct kmem_cache *s, struct slab *slab,
                                      void *head, void *tail, void **p, int cnt,
                                      unsigned long addr)
{
        memcg_slab_free_hook(s, slab, p, cnt);
        /*
         * With KASAN enabled slab_free_freelist_hook modifies the freelist
         * to remove objects, whose reuse must be delayed.
         */
        if (slab_free_freelist_hook(s, &head, &tail, &cnt))
                do_slab_free(s, slab, head, tail, cnt, addr);
}

#ifdef CONFIG_KASAN_GENERIC
void ___cache_free(struct kmem_cache *cache, void *x, unsigned long addr)
{
        do_slab_free(cache, virt_to_slab(x), x, NULL, 1, addr);
}
#endif

void __kmem_cache_free(struct kmem_cache *s, void *x, unsigned long caller)
{
        slab_free(s, virt_to_slab(x), x, NULL, &x, 1, caller);
}

void kmem_cache_free(struct kmem_cache *s, void *x)
{
        s = cache_from_obj(s, x);
        if (!s)
                return;
        trace_kmem_cache_free(_RET_IP_, x, s);
        slab_free(s, virt_to_slab(x), x, NULL, &x, 1, _RET_IP_);
}
EXPORT_SYMBOL(kmem_cache_free);

struct detached_freelist {
        struct slab *slab;
        void *tail;
        void *freelist;
        int cnt;
        struct kmem_cache *s;
};

/*
 * This function progressively scans the array with free objects (with
 * a limited look ahead) and extract objects belonging to the same
 * slab.  It builds a detached freelist directly within the given
 * slab/objects.  This can happen without any need for
 * synchronization, because the objects are owned by running process.
 * The freelist is build up as a single linked list in the objects.
 * The idea is, that this detached freelist can then be bulk
 * transferred to the real freelist(s), but only requiring a single
 * synchronization primitive.  Look ahead in the array is limited due
 * to performance reasons.
 */
static inline
int build_detached_freelist(struct kmem_cache *s, size_t size,
                            void **p, struct detached_freelist *df)
{
        int lookahead = 3;
        void *object;
        struct folio *folio;
        size_t same;

        object = p[--size];
        folio = virt_to_folio(object);
        if (!s) {
                /* Handle kalloc'ed objects */
                if (unlikely(!folio_test_slab(folio))) {
                        free_large_kmalloc(folio, object);
                        df->slab = NULL;
                        return size;
                }
                /* Derive kmem_cache from object */
                df->slab = folio_slab(folio);
                df->s = df->slab->slab_cache;
        } else {
                df->slab = folio_slab(folio);
                df->s = cache_from_obj(s, object); /* Support for memcg */
        }

        /* Start new detached freelist */
        df->tail = object;
        df->freelist = object;
        df->cnt = 1;

        if (is_kfence_address(object))
                return size;

        set_freepointer(df->s, object, NULL);

        same = size;
        while (size) {
                object = p[--size];
                /* df->slab is always set at this point */
                if (df->slab == virt_to_slab(object)) {
                        /* Opportunity build freelist */
                        set_freepointer(df->s, object, df->freelist);
                        df->freelist = object;
                        df->cnt++;
                        same--;
                        if (size != same)
                                swap(p[size], p[same]);
                        continue;
                }

                /* Limit look ahead search */
                if (!--lookahead)
                        break;
        }

        return same;
}

/* Note that interrupts must be enabled when calling this function. */
void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p)
{
        if (!size)
                return;

        do {
                struct detached_freelist df;

                size = build_detached_freelist(s, size, p, &df);
                if (!df.slab)
                        continue;

                slab_free(df.s, df.slab, df.freelist, df.tail, &p[size], df.cnt,
                          _RET_IP_);
        } while (likely(size));
}
EXPORT_SYMBOL(kmem_cache_free_bulk);

/* Note that interrupts must be enabled when calling this function. */
int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
                          void **p)
{
        struct kmem_cache_cpu *c;
        int i;
        struct obj_cgroup *objcg = NULL;

        /* memcg and kmem_cache debug support */
        s = slab_pre_alloc_hook(s, NULL, &objcg, size, flags);
        if (unlikely(!s))
                return false;
        /*
         * Drain objects in the per cpu slab, while disabling local
         * IRQs, which protects against PREEMPT and interrupts
         * handlers invoking normal fastpath.
         */
        c = slub_get_cpu_ptr(s->cpu_slab);
        local_lock_irq(&s->cpu_slab->lock);

        for (i = 0; i < size; i++) {
                void *object = kfence_alloc(s, s->object_size, flags);

                if (unlikely(object)) {
                        p[i] = object;
                        continue;
                }

                object = c->freelist;
                if (unlikely(!object)) {
                        /*
                         * We may have removed an object from c->freelist using
                         * the fastpath in the previous iteration; in that case,
                         * c->tid has not been bumped yet.
                         * Since ___slab_alloc() may reenable interrupts while
                         * allocating memory, we should bump c->tid now.
                         */
                        c->tid = next_tid(c->tid);

                        local_unlock_irq(&s->cpu_slab->lock);

                        /*
                         * Invoking slow path likely have side-effect
                         * of re-populating per CPU c->freelist
                         */
                        p[i] = ___slab_alloc(s, flags, NUMA_NO_NODE,
                                            _RET_IP_, c, s->object_size);
                        if (unlikely(!p[i]))
                                goto error;

                        c = this_cpu_ptr(s->cpu_slab);
                        maybe_wipe_obj_freeptr(s, p[i]);

                        local_lock_irq(&s->cpu_slab->lock);

                        continue; /* goto for-loop */
                }
                c->freelist = get_freepointer(s, object);
                p[i] = object;
                maybe_wipe_obj_freeptr(s, p[i]);
        }
        c->tid = next_tid(c->tid);
        local_unlock_irq(&s->cpu_slab->lock);
        slub_put_cpu_ptr(s->cpu_slab);

        /*
         * memcg and kmem_cache debug support and memory initialization.
         * Done outside of the IRQ disabled fastpath loop.
         */
        slab_post_alloc_hook(s, objcg, flags, size, p,
                                slab_want_init_on_alloc(flags, s));
        return i;
error:
        slub_put_cpu_ptr(s->cpu_slab);
        slab_post_alloc_hook(s, objcg, flags, i, p, false);
        kmem_cache_free_bulk(s, i, p);
        return 0;
}
EXPORT_SYMBOL(kmem_cache_alloc_bulk);


/*
 * Object placement in a slab is made very easy because we always start at
 * offset 0. If we tune the size of the object to the alignment then we can
 * get the required alignment by putting one properly sized object after
 * another.
 *
 * Notice that the allocation order determines the sizes of the per cpu
 * caches. Each processor has always one slab available for allocations.
 * Increasing the allocation order reduces the number of times that slabs
 * must be moved on and off the partial lists and is therefore a factor in
 * locking overhead.
 */

/*
 * Minimum / Maximum order of slab pages. This influences locking overhead
 * and slab fragmentation. A higher order reduces the number of partial slabs
 * and increases the number of allocations possible without having to
 * take the list_lock.
 */
static unsigned int slub_min_order;
static unsigned int slub_max_order = PAGE_ALLOC_COSTLY_ORDER;
static unsigned int slub_min_objects;

/*
 * Calculate the order of allocation given an slab object size.
 *
 * The order of allocation has significant impact on performance and other
 * system components. Generally order 0 allocations should be preferred since
 * order 0 does not cause fragmentation in the page allocator. Larger objects
 * be problematic to put into order 0 slabs because there may be too much
 * unused space left. We go to a higher order if more than 1/16th of the slab
 * would be wasted.
 *
 * In order to reach satisfactory performance we must ensure that a minimum
 * number of objects is in one slab. Otherwise we may generate too much
 * activity on the partial lists which requires taking the list_lock. This is
 * less a concern for large slabs though which are rarely used.
 *
 * slub_max_order specifies the order where we begin to stop considering the
 * number of objects in a slab as critical. If we reach slub_max_order then
 * we try to keep the page order as low as possible. So we accept more waste
 * of space in favor of a small page order.
 *
 * Higher order allocations also allow the placement of more objects in a
 * slab and thereby reduce object handling overhead. If the user has
 * requested a higher minimum order then we start with that one instead of
 * the smallest order which will fit the object.
 */
static inline unsigned int calc_slab_order(unsigned int size,
                unsigned int min_objects, unsigned int max_order,
                unsigned int fract_leftover)
{
        unsigned int min_order = slub_min_order;
        unsigned int order;

        if (order_objects(min_order, size) > MAX_OBJS_PER_PAGE)
                return get_order(size * MAX_OBJS_PER_PAGE) - 1;

        for (order = max(min_order, (unsigned int)get_order(min_objects * size));
                        order <= max_order; order++) {

                unsigned int slab_size = (unsigned int)PAGE_SIZE << order;
                unsigned int rem;

                rem = slab_size % size;

                if (rem <= slab_size / fract_leftover)
                        break;
        }

        return order;
}

static inline int calculate_order(unsigned int size)
{
        unsigned int order;
        unsigned int min_objects;
        unsigned int max_objects;
        unsigned int nr_cpus;

        /*
         * Attempt to find best configuration for a slab. This
         * works by first attempting to generate a layout with
         * the best configuration and backing off gradually.
         *
         * First we increase the acceptable waste in a slab. Then
         * we reduce the minimum objects required in a slab.
         */
        min_objects = slub_min_objects;
        if (!min_objects) {
                /*
                 * Some architectures will only update present cpus when
                 * onlining them, so don't trust the number if it's just 1. But
                 * we also don't want to use nr_cpu_ids always, as on some other
                 * architectures, there can be many possible cpus, but never
                 * onlined. Here we compromise between trying to avoid too high
                 * order on systems that appear larger than they are, and too
                 * low order on systems that appear smaller than they are.
                 */
                nr_cpus = num_present_cpus();
                if (nr_cpus <= 1)
                        nr_cpus = nr_cpu_ids;
                min_objects = 4 * (fls(nr_cpus) + 1);
        }
        max_objects = order_objects(slub_max_order, size);
        min_objects = min(min_objects, max_objects);

        while (min_objects > 1) {
                unsigned int fraction;

                fraction = 16;
                while (fraction >= 4) {
                        order = calc_slab_order(size, min_objects,
                                        slub_max_order, fraction);
                        if (order <= slub_max_order)
                                return order;
                        fraction /= 2;
                }
                min_objects--;
        }

        /*
         * We were unable to place multiple objects in a slab. Now
         * lets see if we can place a single object there.
         */
        order = calc_slab_order(size, 1, slub_max_order, 1);
        if (order <= slub_max_order)
                return order;

        /*
         * Doh this slab cannot be placed using slub_max_order.
         */
        order = calc_slab_order(size, 1, MAX_ORDER, 1);
        if (order < MAX_ORDER)
                return order;
        return -ENOSYS;
}

static void
init_kmem_cache_node(struct kmem_cache_node *n)
{
        n->nr_partial = 0;
        spin_lock_init(&n->list_lock);
        INIT_LIST_HEAD(&n->partial);
#ifdef CONFIG_SLUB_DEBUG
        atomic_long_set(&n->nr_slabs, 0);
        atomic_long_set(&n->total_objects, 0);
        INIT_LIST_HEAD(&n->full);
#endif
}

static inline int alloc_kmem_cache_cpus(struct kmem_cache *s)
{
        BUILD_BUG_ON(PERCPU_DYNAMIC_EARLY_SIZE <
                        KMALLOC_SHIFT_HIGH * sizeof(struct kmem_cache_cpu));

        /*
         * Must align to double word boundary for the double cmpxchg
         * instructions to work; see __pcpu_double_call_return_bool().
         */
        s->cpu_slab = __alloc_percpu(sizeof(struct kmem_cache_cpu),
                                     2 * sizeof(void *));

        if (!s->cpu_slab)
                return 0;

        init_kmem_cache_cpus(s);

        return 1;
}

static struct kmem_cache *kmem_cache_node;

/*
 * No kmalloc_node yet so do it by hand. We know that this is the first
 * slab on the node for this slabcache. There are no concurrent accesses
 * possible.
 *
 * Note that this function only works on the kmem_cache_node
 * when allocating for the kmem_cache_node. This is used for bootstrapping
 * memory on a fresh node that has no slab structures yet.
 */
static void early_kmem_cache_node_alloc(int node)
{
        struct slab *slab;
        struct kmem_cache_node *n;

        BUG_ON(kmem_cache_node->size < sizeof(struct kmem_cache_node));

        slab = new_slab(kmem_cache_node, GFP_NOWAIT, node);

        BUG_ON(!slab);
        inc_slabs_node(kmem_cache_node, slab_nid(slab), slab->objects);
        if (slab_nid(slab) != node) {
                pr_err("SLUB: Unable to allocate memory from node %d\n", node);
                pr_err("SLUB: Allocating a useless per node structure in order to be able to continue\n");
        }

        n = slab->freelist;
        BUG_ON(!n);
#ifdef CONFIG_SLUB_DEBUG
        init_object(kmem_cache_node, n, SLUB_RED_ACTIVE);
        init_tracking(kmem_cache_node, n);
#endif
        n = kasan_slab_alloc(kmem_cache_node, n, GFP_KERNEL, false);
        slab->freelist = get_freepointer(kmem_cache_node, n);
        slab->inuse = 1;
        kmem_cache_node->node[node] = n;
        init_kmem_cache_node(n);
        inc_slabs_node(kmem_cache_node, node, slab->objects);

        /*
         * No locks need to be taken here as it has just been
         * initialized and there is no concurrent access.
         */
        __add_partial(n, slab, DEACTIVATE_TO_HEAD);
}

static void free_kmem_cache_nodes(struct kmem_cache *s)
{
        int node;
        struct kmem_cache_node *n;

        for_each_kmem_cache_node(s, node, n) {
                s->node[node] = NULL;
                kmem_cache_free(kmem_cache_node, n);
        }
}

void __kmem_cache_release(struct kmem_cache *s)
{
        cache_random_seq_destroy(s);
        free_percpu(s->cpu_slab);
        free_kmem_cache_nodes(s);
}

static int init_kmem_cache_nodes(struct kmem_cache *s)
{
        int node;

        for_each_node_mask(node, slab_nodes) {
                struct kmem_cache_node *n;

                if (slab_state == DOWN) {
                        early_kmem_cache_node_alloc(node);
                        continue;
                }
                n = kmem_cache_alloc_node(kmem_cache_node,
                                                GFP_KERNEL, node);

                if (!n) {
                        free_kmem_cache_nodes(s);
                        return 0;
                }

                init_kmem_cache_node(n);
                s->node[node] = n;
        }
        return 1;
}

static void set_cpu_partial(struct kmem_cache *s)
{
#ifdef CONFIG_SLUB_CPU_PARTIAL
        unsigned int nr_objects;

        /*
         * cpu_partial determined the maximum number of objects kept in the
         * per cpu partial lists of a processor.
         *
         * Per cpu partial lists mainly contain slabs that just have one
         * object freed. If they are used for allocation then they can be
         * filled up again with minimal effort. The slab will never hit the
         * per node partial lists and therefore no locking will be required.
         *
         * For backwards compatibility reasons, this is determined as number
         * of objects, even though we now limit maximum number of pages, see
         * slub_set_cpu_partial()
         */
        if (!kmem_cache_has_cpu_partial(s))
                nr_objects = 0;
        else if (s->size >= PAGE_SIZE)
                nr_objects = 6;
        else if (s->size >= 1024)
                nr_objects = 24;
        else if (s->size >= 256)
                nr_objects = 52;
        else
                nr_objects = 120;

        slub_set_cpu_partial(s, nr_objects);
#endif
}

/*
 * calculate_sizes() determines the order and the distribution of data within
 * a slab object.
 */
static int calculate_sizes(struct kmem_cache *s)
{
        slab_flags_t flags = s->flags;
        unsigned int size = s->object_size;
        unsigned int order;

        /*
         * Round up object size to the next word boundary. We can only
         * place the free pointer at word boundaries and this determines
         * the possible location of the free pointer.
         */
        size = ALIGN(size, sizeof(void *));

#ifdef CONFIG_SLUB_DEBUG
        /*
         * Determine if we can poison the object itself. If the user of
         * the slab may touch the object after free or before allocation
         * then we should never poison the object itself.
         */
        if ((flags & SLAB_POISON) && !(flags & SLAB_TYPESAFE_BY_RCU) &&
                        !s->ctor)
                s->flags |= __OBJECT_POISON;
        else
                s->flags &= ~__OBJECT_POISON;


        /*
         * If we are Redzoning then check if there is some space between the
         * end of the object and the free pointer. If not then add an
         * additional word to have some bytes to store Redzone information.
         */
        if ((flags & SLAB_RED_ZONE) && size == s->object_size)
                size += sizeof(void *);
#endif

        /*
         * With that we have determined the number of bytes in actual use
         * by the object and redzoning.
         */
        s->inuse = size;

        if ((flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)) ||
            ((flags & SLAB_RED_ZONE) && s->object_size < sizeof(void *)) ||
            s->ctor) {
                /*
                 * Relocate free pointer after the object if it is not
                 * permitted to overwrite the first word of the object on
                 * kmem_cache_free.
                 *
                 * This is the case if we do RCU, have a constructor or
                 * destructor, are poisoning the objects, or are
                 * redzoning an object smaller than sizeof(void *).
                 *
                 * The assumption that s->offset >= s->inuse means free
                 * pointer is outside of the object is used in the
                 * freeptr_outside_object() function. If that is no
                 * longer true, the function needs to be modified.
                 */
                s->offset = size;
                size += sizeof(void *);
        } else {
                /*
                 * Store freelist pointer near middle of object to keep
                 * it away from the edges of the object to avoid small
                 * sized over/underflows from neighboring allocations.
                 */
                s->offset = ALIGN_DOWN(s->object_size / 2, sizeof(void *));
        }

#ifdef CONFIG_SLUB_DEBUG
        if (flags & SLAB_STORE_USER) {
                /*
                 * Need to store information about allocs and frees after
                 * the object.
                 */
                size += 2 * sizeof(struct track);

                /* Save the original kmalloc request size */
                if (flags & SLAB_KMALLOC)
                        size += sizeof(unsigned int);
        }
#endif

        kasan_cache_create(s, &size, &s->flags);
#ifdef CONFIG_SLUB_DEBUG
        if (flags & SLAB_RED_ZONE) {
                /*
                 * Add some empty padding so that we can catch
                 * overwrites from earlier objects rather than let
                 * tracking information or the free pointer be
                 * corrupted if a user writes before the start
                 * of the object.
                 */
                size += sizeof(void *);

                s->red_left_pad = sizeof(void *);
                s->red_left_pad = ALIGN(s->red_left_pad, s->align);
                size += s->red_left_pad;
        }
#endif

        /*
         * SLUB stores one object immediately after another beginning from
         * offset 0. In order to align the objects we have to simply size
         * each object to conform to the alignment.
         */
        size = ALIGN(size, s->align);
        s->size = size;
        s->reciprocal_size = reciprocal_value(size);
        order = calculate_order(size);

        if ((int)order < 0)
                return 0;

        s->allocflags = 0;
        if (order)
                s->allocflags |= __GFP_COMP;

        if (s->flags & SLAB_CACHE_DMA)
                s->allocflags |= GFP_DMA;

        if (s->flags & SLAB_CACHE_DMA32)
                s->allocflags |= GFP_DMA32;

        if (s->flags & SLAB_RECLAIM_ACCOUNT)
                s->allocflags |= __GFP_RECLAIMABLE;

        /*
         * Determine the number of objects per slab
         */
        s->oo = oo_make(order, size);
        s->min = oo_make(get_order(size), size);

        return !!oo_objects(s->oo);
}

static int kmem_cache_open(struct kmem_cache *s, slab_flags_t flags)
{
        s->flags = kmem_cache_flags(s->size, flags, s->name);
#ifdef CONFIG_SLAB_FREELIST_HARDENED
        s->random = get_random_long();
#endif

        if (!calculate_sizes(s))
                goto error;
        if (disable_higher_order_debug) {
                /*
                 * Disable debugging flags that store metadata if the min slab
                 * order increased.
                 */
                if (get_order(s->size) > get_order(s->object_size)) {
                        s->flags &= ~DEBUG_METADATA_FLAGS;
                        s->offset = 0;
                        if (!calculate_sizes(s))
                                goto error;
                }
        }

#if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
    defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
        if (system_has_cmpxchg_double() && (s->flags & SLAB_NO_CMPXCHG) == 0)
                /* Enable fast mode */
                s->flags |= __CMPXCHG_DOUBLE;
#endif

        /*
         * The larger the object size is, the more slabs we want on the partial
         * list to avoid pounding the page allocator excessively.
         */
        s->min_partial = min_t(unsigned long, MAX_PARTIAL, ilog2(s->size) / 2);
        s->min_partial = max_t(unsigned long, MIN_PARTIAL, s->min_partial);

        set_cpu_partial(s);

#ifdef CONFIG_NUMA
        s->remote_node_defrag_ratio = 1000;
#endif

        /* Initialize the pre-computed randomized freelist if slab is up */
        if (slab_state >= UP) {
                if (init_cache_random_seq(s))
                        goto error;
        }

        if (!init_kmem_cache_nodes(s))
                goto error;

        if (alloc_kmem_cache_cpus(s))
                return 0;

error:
        __kmem_cache_release(s);
        return -EINVAL;
}

static void list_slab_objects(struct kmem_cache *s, struct slab *slab,
                              const char *text)
{
#ifdef CONFIG_SLUB_DEBUG
        void *addr = slab_address(slab);
        void *p;

        slab_err(s, slab, text, s->name);

        spin_lock(&object_map_lock);
        __fill_map(object_map, s, slab);

        for_each_object(p, s, addr, slab->objects) {

                if (!test_bit(__obj_to_index(s, addr, p), object_map)) {
                        pr_err("Object 0x%p @offset=%tu\n", p, p - addr);
                        print_tracking(s, p);
                }
        }
        spin_unlock(&object_map_lock);
#endif
}

/*
 * Attempt to free all partial slabs on a node.
 * This is called from __kmem_cache_shutdown(). We must take list_lock
 * because sysfs file might still access partial list after the shutdowning.
 */
static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n)
{
        LIST_HEAD(discard);
        struct slab *slab, *h;

        BUG_ON(irqs_disabled());
        spin_lock_irq(&n->list_lock);
        list_for_each_entry_safe(slab, h, &n->partial, slab_list) {
                if (!slab->inuse) {
                        remove_partial(n, slab);
                        list_add(&slab->slab_list, &discard);
                } else {
                        list_slab_objects(s, slab,
                          "Objects remaining in %s on __kmem_cache_shutdown()");
                }
        }
        spin_unlock_irq(&n->list_lock);

        list_for_each_entry_safe(slab, h, &discard, slab_list)
                discard_slab(s, slab);
}

bool __kmem_cache_empty(struct kmem_cache *s)
{
        int node;
        struct kmem_cache_node *n;

        for_each_kmem_cache_node(s, node, n)
                if (n->nr_partial || slabs_node(s, node))
                        return false;
        return true;
}

/*
 * Release all resources used by a slab cache.
 */
int __kmem_cache_shutdown(struct kmem_cache *s)
{
        int node;
        struct kmem_cache_node *n;

        flush_all_cpus_locked(s);
        /* Attempt to free all objects */
        for_each_kmem_cache_node(s, node, n) {
                free_partial(s, n);
                if (n->nr_partial || slabs_node(s, node))
                        return 1;
        }
        return 0;
}

#ifdef CONFIG_PRINTK
void __kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab)
{
        void *base;
        int __maybe_unused i;
        unsigned int objnr;
        void *objp;
        void *objp0;
        struct kmem_cache *s = slab->slab_cache;
        struct track __maybe_unused *trackp;

        kpp->kp_ptr = object;
        kpp->kp_slab = slab;
        kpp->kp_slab_cache = s;
        base = slab_address(slab);
        objp0 = kasan_reset_tag(object);
#ifdef CONFIG_SLUB_DEBUG
        objp = restore_red_left(s, objp0);
#else
        objp = objp0;
#endif
        objnr = obj_to_index(s, slab, objp);
        kpp->kp_data_offset = (unsigned long)((char *)objp0 - (char *)objp);
        objp = base + s->size * objnr;
        kpp->kp_objp = objp;
        if (WARN_ON_ONCE(objp < base || objp >= base + slab->objects * s->size
                         || (objp - base) % s->size) ||
            !(s->flags & SLAB_STORE_USER))
                return;
#ifdef CONFIG_SLUB_DEBUG
        objp = fixup_red_left(s, objp);
        trackp = get_track(s, objp, TRACK_ALLOC);
        kpp->kp_ret = (void *)trackp->addr;
#ifdef CONFIG_STACKDEPOT
        {
                depot_stack_handle_t handle;
                unsigned long *entries;
                unsigned int nr_entries;

                handle = READ_ONCE(trackp->handle);
                if (handle) {
                        nr_entries = stack_depot_fetch(handle, &entries);
                        for (i = 0; i < KS_ADDRS_COUNT && i < nr_entries; i++)
                                kpp->kp_stack[i] = (void *)entries[i];
                }

                trackp = get_track(s, objp, TRACK_FREE);
                handle = READ_ONCE(trackp->handle);
                if (handle) {
                        nr_entries = stack_depot_fetch(handle, &entries);
                        for (i = 0; i < KS_ADDRS_COUNT && i < nr_entries; i++)
                                kpp->kp_free_stack[i] = (void *)entries[i];
                }
        }
#endif
#endif
}
#endif

/********************************************************************
 *              Kmalloc subsystem
 *******************************************************************/

static int __init setup_slub_min_order(char *str)
{
        get_option(&str, (int *)&slub_min_order);

        return 1;
}

__setup("slub_min_order=", setup_slub_min_order);

static int __init setup_slub_max_order(char *str)
{
        get_option(&str, (int *)&slub_max_order);
        slub_max_order = min(slub_max_order, (unsigned int)MAX_ORDER - 1);

        return 1;
}

__setup("slub_max_order=", setup_slub_max_order);

static int __init setup_slub_min_objects(char *str)
{
        get_option(&str, (int *)&slub_min_objects);

        return 1;
}

__setup("slub_min_objects=", setup_slub_min_objects);

#ifdef CONFIG_HARDENED_USERCOPY
/*
 * Rejects incorrectly sized objects and objects that are to be copied
 * to/from userspace but do not fall entirely within the containing slab
 * cache's usercopy region.
 *
 * Returns NULL if check passes, otherwise const char * to name of cache
 * to indicate an error.
 */
void __check_heap_object(const void *ptr, unsigned long n,
                         const struct slab *slab, bool to_user)
{
        struct kmem_cache *s;
        unsigned int offset;
        bool is_kfence = is_kfence_address(ptr);

        ptr = kasan_reset_tag(ptr);

        /* Find object and usable object size. */
        s = slab->slab_cache;

        /* Reject impossible pointers. */
        if (ptr < slab_address(slab))
                usercopy_abort("SLUB object not in SLUB page?!", NULL,
                               to_user, 0, n);

        /* Find offset within object. */
        if (is_kfence)
                offset = ptr - kfence_object_start(ptr);
        else
                offset = (ptr - slab_address(slab)) % s->size;

        /* Adjust for redzone and reject if within the redzone. */
        if (!is_kfence && kmem_cache_debug_flags(s, SLAB_RED_ZONE)) {
                if (offset < s->red_left_pad)
                        usercopy_abort("SLUB object in left red zone",
                                       s->name, to_user, offset, n);
                offset -= s->red_left_pad;
        }

        /* Allow address range falling entirely within usercopy region. */
        if (offset >= s->useroffset &&
            offset - s->useroffset <= s->usersize &&
            n <= s->useroffset - offset + s->usersize)
                return;

        usercopy_abort("SLUB object", s->name, to_user, offset, n);
}
#endif /* CONFIG_HARDENED_USERCOPY */

#define SHRINK_PROMOTE_MAX 32

/*
 * kmem_cache_shrink discards empty slabs and promotes the slabs filled
 * up most to the head of the partial lists. New allocations will then
 * fill those up and thus they can be removed from the partial lists.
 *
 * The slabs with the least items are placed last. This results in them
 * being allocated from last increasing the chance that the last objects
 * are freed in them.
 */
static int __kmem_cache_do_shrink(struct kmem_cache *s)
{
        int node;
        int i;
        struct kmem_cache_node *n;
        struct slab *slab;
        struct slab *t;
        struct list_head discard;
        struct list_head promote[SHRINK_PROMOTE_MAX];
        unsigned long flags;
        int ret = 0;

        for_each_kmem_cache_node(s, node, n) {
                INIT_LIST_HEAD(&discard);
                for (i = 0; i < SHRINK_PROMOTE_MAX; i++)
                        INIT_LIST_HEAD(promote + i);

                spin_lock_irqsave(&n->list_lock, flags);

                /*
                 * Build lists of slabs to discard or promote.
                 *
                 * Note that concurrent frees may occur while we hold the
                 * list_lock. slab->inuse here is the upper limit.
                 */
                list_for_each_entry_safe(slab, t, &n->partial, slab_list) {
                        int free = slab->objects - slab->inuse;

                        /* Do not reread slab->inuse */
                        barrier();

                        /* We do not keep full slabs on the list */
                        BUG_ON(free <= 0);

                        if (free == slab->objects) {
                                list_move(&slab->slab_list, &discard);
                                n->nr_partial--;
                                dec_slabs_node(s, node, slab->objects);
                        } else if (free <= SHRINK_PROMOTE_MAX)
                                list_move(&slab->slab_list, promote + free - 1);
                }

                /*
                 * Promote the slabs filled up most to the head of the
                 * partial list.
                 */
                for (i = SHRINK_PROMOTE_MAX - 1; i >= 0; i--)
                        list_splice(promote + i, &n->partial);

                spin_unlock_irqrestore(&n->list_lock, flags);

                /* Release empty slabs */
                list_for_each_entry_safe(slab, t, &discard, slab_list)
                        free_slab(s, slab);

                if (slabs_node(s, node))
                        ret = 1;
        }

        return ret;
}

int __kmem_cache_shrink(struct kmem_cache *s)
{
        flush_all(s);
        return __kmem_cache_do_shrink(s);
}

static int slab_mem_going_offline_callback(void *arg)
{
        struct kmem_cache *s;

        mutex_lock(&slab_mutex);
        list_for_each_entry(s, &slab_caches, list) {
                flush_all_cpus_locked(s);
                __kmem_cache_do_shrink(s);
        }
        mutex_unlock(&slab_mutex);

        return 0;
}

static void slab_mem_offline_callback(void *arg)
{
        struct memory_notify *marg = arg;
        int offline_node;

        offline_node = marg->status_change_nid_normal;

        /*
         * If the node still has available memory. we need kmem_cache_node
         * for it yet.
         */
        if (offline_node < 0)
                return;

        mutex_lock(&slab_mutex);
        node_clear(offline_node, slab_nodes);
        /*
         * We no longer free kmem_cache_node structures here, as it would be
         * racy with all get_node() users, and infeasible to protect them with
         * slab_mutex.
         */
        mutex_unlock(&slab_mutex);
}

static int slab_mem_going_online_callback(void *arg)
{
        struct kmem_cache_node *n;
        struct kmem_cache *s;
        struct memory_notify *marg = arg;
        int nid = marg->status_change_nid_normal;
        int ret = 0;

        /*
         * If the node's memory is already available, then kmem_cache_node is
         * already created. Nothing to do.
         */
        if (nid < 0)
                return 0;

        /*
         * We are bringing a node online. No memory is available yet. We must
         * allocate a kmem_cache_node structure in order to bring the node
         * online.
         */
        mutex_lock(&slab_mutex);
        list_for_each_entry(s, &slab_caches, list) {
                /*
                 * The structure may already exist if the node was previously
                 * onlined and offlined.
                 */
                if (get_node(s, nid))
                        continue;
                /*
                 * XXX: kmem_cache_alloc_node will fallback to other nodes
                 *      since memory is not yet available from the node that
                 *      is brought up.
                 */
                n = kmem_cache_alloc(kmem_cache_node, GFP_KERNEL);
                if (!n) {
                        ret = -ENOMEM;
                        goto out;
                }
                init_kmem_cache_node(n);
                s->node[nid] = n;
        }
        /*
         * Any cache created after this point will also have kmem_cache_node
         * initialized for the new node.
         */
        node_set(nid, slab_nodes);
out:
        mutex_unlock(&slab_mutex);
        return ret;
}

static int slab_memory_callback(struct notifier_block *self,
                                unsigned long action, void *arg)
{
        int ret = 0;

        switch (action) {
        case MEM_GOING_ONLINE:
                ret = slab_mem_going_online_callback(arg);
                break;
        case MEM_GOING_OFFLINE:
                ret = slab_mem_going_offline_callback(arg);
                break;
        case MEM_OFFLINE:
        case MEM_CANCEL_ONLINE:
                slab_mem_offline_callback(arg);
                break;
        case MEM_ONLINE:
        case MEM_CANCEL_OFFLINE:
                break;
        }
        if (ret)
                ret = notifier_from_errno(ret);
        else
                ret = NOTIFY_OK;
        return ret;
}

static struct notifier_block slab_memory_callback_nb = {
        .notifier_call = slab_memory_callback,
        .priority = SLAB_CALLBACK_PRI,
};

/********************************************************************
 *                      Basic setup of slabs
 *******************************************************************/

/*
 * Used for early kmem_cache structures that were allocated using
 * the page allocator. Allocate them properly then fix up the pointers
 * that may be pointing to the wrong kmem_cache structure.
 */

static struct kmem_cache * __init bootstrap(struct kmem_cache *static_cache)
{
        int node;
        struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
        struct kmem_cache_node *n;

        memcpy(s, static_cache, kmem_cache->object_size);

        /*
         * This runs very early, and only the boot processor is supposed to be
         * up.  Even if it weren't true, IRQs are not up so we couldn't fire
         * IPIs around.
         */
        __flush_cpu_slab(s, smp_processor_id());
        for_each_kmem_cache_node(s, node, n) {
                struct slab *p;

                list_for_each_entry(p, &n->partial, slab_list)
                        p->slab_cache = s;

#ifdef CONFIG_SLUB_DEBUG
                list_for_each_entry(p, &n->full, slab_list)
                        p->slab_cache = s;
#endif
        }
        list_add(&s->list, &slab_caches);
        return s;
}

void __init kmem_cache_init(void)
{
        static __initdata struct kmem_cache boot_kmem_cache,
                boot_kmem_cache_node;
        int node;

        if (debug_guardpage_minorder())
                slub_max_order = 0;

        /* Print slub debugging pointers without hashing */
        if (__slub_debug_enabled())
                no_hash_pointers_enable(NULL);

        kmem_cache_node = &boot_kmem_cache_node;
        kmem_cache = &boot_kmem_cache;

        /*
         * Initialize the nodemask for which we will allocate per node
         * structures. Here we don't need taking slab_mutex yet.
         */
        for_each_node_state(node, N_NORMAL_MEMORY)
                node_set(node, slab_nodes);

        create_boot_cache(kmem_cache_node, "kmem_cache_node",
                sizeof(struct kmem_cache_node), SLAB_HWCACHE_ALIGN, 0, 0);

        register_hotmemory_notifier(&slab_memory_callback_nb);

        /* Able to allocate the per node structures */
        slab_state = PARTIAL;

        create_boot_cache(kmem_cache, "kmem_cache",
                        offsetof(struct kmem_cache, node) +
                                nr_node_ids * sizeof(struct kmem_cache_node *),
                       SLAB_HWCACHE_ALIGN, 0, 0);

        kmem_cache = bootstrap(&boot_kmem_cache);
        kmem_cache_node = bootstrap(&boot_kmem_cache_node);

        /* Now we can use the kmem_cache to allocate kmalloc slabs */
        setup_kmalloc_cache_index_table();
        create_kmalloc_caches(0);

        /* Setup random freelists for each cache */
        init_freelist_randomization();

        cpuhp_setup_state_nocalls(CPUHP_SLUB_DEAD, "slub:dead", NULL,
                                  slub_cpu_dead);

        pr_info("SLUB: HWalign=%d, Order=%u-%u, MinObjects=%u, CPUs=%u, Nodes=%u\n",
                cache_line_size(),
                slub_min_order, slub_max_order, slub_min_objects,
                nr_cpu_ids, nr_node_ids);
}

void __init kmem_cache_init_late(void)
{
        flushwq = alloc_workqueue("slub_flushwq", WQ_MEM_RECLAIM, 0);
        WARN_ON(!flushwq);
}

struct kmem_cache *
__kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
                   slab_flags_t flags, void (*ctor)(void *))
{
        struct kmem_cache *s;

        s = find_mergeable(size, align, flags, name, ctor);
        if (s) {
                if (sysfs_slab_alias(s, name))
                        return NULL;

                s->refcount++;

                /*
                 * Adjust the object sizes so that we clear
                 * the complete object on kzalloc.
                 */
                s->object_size = max(s->object_size, size);
                s->inuse = max(s->inuse, ALIGN(size, sizeof(void *)));
        }

        return s;
}

int __kmem_cache_create(struct kmem_cache *s, slab_flags_t flags)
{
        int err;

        err = kmem_cache_open(s, flags);
        if (err)
                return err;

        /* Mutex is not taken during early boot */
        if (slab_state <= UP)
                return 0;

        err = sysfs_slab_add(s);
        if (err) {
                __kmem_cache_release(s);
                return err;
        }

        if (s->flags & SLAB_STORE_USER)
                debugfs_slab_add(s);

        return 0;
}

#ifdef CONFIG_SYSFS
static int count_inuse(struct slab *slab)
{
        return slab->inuse;
}

static int count_total(struct slab *slab)
{
        return slab->objects;
}
#endif

#ifdef CONFIG_SLUB_DEBUG
static void validate_slab(struct kmem_cache *s, struct slab *slab,
                          unsigned long *obj_map)
{
        void *p;
        void *addr = slab_address(slab);

        if (!check_slab(s, slab) || !on_freelist(s, slab, NULL))
                return;

        /* Now we know that a valid freelist exists */
        __fill_map(obj_map, s, slab);
        for_each_object(p, s, addr, slab->objects) {
                u8 val = test_bit(__obj_to_index(s, addr, p), obj_map) ?
                         SLUB_RED_INACTIVE : SLUB_RED_ACTIVE;

                if (!check_object(s, slab, p, val))
                        break;
        }
}

static int validate_slab_node(struct kmem_cache *s,
                struct kmem_cache_node *n, unsigned long *obj_map)
{
        unsigned long count = 0;
        struct slab *slab;
        unsigned long flags;

        spin_lock_irqsave(&n->list_lock, flags);

        list_for_each_entry(slab, &n->partial, slab_list) {
                validate_slab(s, slab, obj_map);
                count++;
        }
        if (count != n->nr_partial) {
                pr_err("SLUB %s: %ld partial slabs counted but counter=%ld\n",
                       s->name, count, n->nr_partial);
                slab_add_kunit_errors();
        }

        if (!(s->flags & SLAB_STORE_USER))
                goto out;

        list_for_each_entry(slab, &n->full, slab_list) {
                validate_slab(s, slab, obj_map);
                count++;
        }
        if (count != atomic_long_read(&n->nr_slabs)) {
                pr_err("SLUB: %s %ld slabs counted but counter=%ld\n",
                       s->name, count, atomic_long_read(&n->nr_slabs));
                slab_add_kunit_errors();
        }

out:
        spin_unlock_irqrestore(&n->list_lock, flags);
        return count;
}

long validate_slab_cache(struct kmem_cache *s)
{
        int node;
        unsigned long count = 0;
        struct kmem_cache_node *n;
        unsigned long *obj_map;

        obj_map = bitmap_alloc(oo_objects(s->oo), GFP_KERNEL);
        if (!obj_map)
                return -ENOMEM;

        flush_all(s);
        for_each_kmem_cache_node(s, node, n)
                count += validate_slab_node(s, n, obj_map);

        bitmap_free(obj_map);

        return count;
}
EXPORT_SYMBOL(validate_slab_cache);

#ifdef CONFIG_DEBUG_FS
/*
 * Generate lists of code addresses where slabcache objects are allocated
 * and freed.
 */

struct location {
        depot_stack_handle_t handle;
        unsigned long count;
        unsigned long addr;
        unsigned long waste;
        long long sum_time;
        long min_time;
        long max_time;
        long min_pid;
        long max_pid;
        DECLARE_BITMAP(cpus, NR_CPUS);
        nodemask_t nodes;
};

struct loc_track {
        unsigned long max;
        unsigned long count;
        struct location *loc;
        loff_t idx;
};

static struct dentry *slab_debugfs_root;

static void free_loc_track(struct loc_track *t)
{
        if (t->max)
                free_pages((unsigned long)t->loc,
                        get_order(sizeof(struct location) * t->max));
}

static int alloc_loc_track(struct loc_track *t, unsigned long max, gfp_t flags)
{
        struct location *l;
        int order;

        order = get_order(sizeof(struct location) * max);

        l = (void *)__get_free_pages(flags, order);
        if (!l)
                return 0;

        if (t->count) {
                memcpy(l, t->loc, sizeof(struct location) * t->count);
                free_loc_track(t);
        }
        t->max = max;
        t->loc = l;
        return 1;
}

static int add_location(struct loc_track *t, struct kmem_cache *s,
                                const struct track *track,
                                unsigned int orig_size)
{
        long start, end, pos;
        struct location *l;
        unsigned long caddr, chandle, cwaste;
        unsigned long age = jiffies - track->when;
        depot_stack_handle_t handle = 0;
        unsigned int waste = s->object_size - orig_size;

#ifdef CONFIG_STACKDEPOT
        handle = READ_ONCE(track->handle);
#endif
        start = -1;
        end = t->count;

        for ( ; ; ) {
                pos = start + (end - start + 1) / 2;

                /*
                 * There is nothing at "end". If we end up there
                 * we need to add something to before end.
                 */
                if (pos == end)
                        break;

                l = &t->loc[pos];
                caddr = l->addr;
                chandle = l->handle;
                cwaste = l->waste;
                if ((track->addr == caddr) && (handle == chandle) &&
                        (waste == cwaste)) {

                        l->count++;
                        if (track->when) {
                                l->sum_time += age;
                                if (age < l->min_time)
                                        l->min_time = age;
                                if (age > l->max_time)
                                        l->max_time = age;

                                if (track->pid < l->min_pid)
                                        l->min_pid = track->pid;
                                if (track->pid > l->max_pid)
                                        l->max_pid = track->pid;

                                cpumask_set_cpu(track->cpu,
                                                to_cpumask(l->cpus));
                        }
                        node_set(page_to_nid(virt_to_page(track)), l->nodes);
                        return 1;
                }

                if (track->addr < caddr)
                        end = pos;
                else if (track->addr == caddr && handle < chandle)
                        end = pos;
                else if (track->addr == caddr && handle == chandle &&
                                waste < cwaste)
                        end = pos;
                else
                        start = pos;
        }

        /*
         * Not found. Insert new tracking element.
         */
        if (t->count >= t->max && !alloc_loc_track(t, 2 * t->max, GFP_ATOMIC))
                return 0;

        l = t->loc + pos;
        if (pos < t->count)
                memmove(l + 1, l,
                        (t->count - pos) * sizeof(struct location));
        t->count++;
        l->count = 1;
        l->addr = track->addr;
        l->sum_time = age;
        l->min_time = age;
        l->max_time = age;
        l->min_pid = track->pid;
        l->max_pid = track->pid;
        l->handle = handle;
        l->waste = waste;
        cpumask_clear(to_cpumask(l->cpus));
        cpumask_set_cpu(track->cpu, to_cpumask(l->cpus));
        nodes_clear(l->nodes);
        node_set(page_to_nid(virt_to_page(track)), l->nodes);
        return 1;
}

static void process_slab(struct loc_track *t, struct kmem_cache *s,
                struct slab *slab, enum track_item alloc,
                unsigned long *obj_map)
{
        void *addr = slab_address(slab);
        bool is_alloc = (alloc == TRACK_ALLOC);
        void *p;

        __fill_map(obj_map, s, slab);

        for_each_object(p, s, addr, slab->objects)
                if (!test_bit(__obj_to_index(s, addr, p), obj_map))
                        add_location(t, s, get_track(s, p, alloc),
                                     is_alloc ? get_orig_size(s, p) :
                                                s->object_size);
}
#endif  /* CONFIG_DEBUG_FS   */
#endif  /* CONFIG_SLUB_DEBUG */

#ifdef CONFIG_SYSFS
enum slab_stat_type {
        SL_ALL,                 /* All slabs */
        SL_PARTIAL,             /* Only partially allocated slabs */
        SL_CPU,                 /* Only slabs used for cpu caches */
        SL_OBJECTS,             /* Determine allocated objects not slabs */
        SL_TOTAL                /* Determine object capacity not slabs */
};

#define SO_ALL          (1 << SL_ALL)
#define SO_PARTIAL      (1 << SL_PARTIAL)
#define SO_CPU          (1 << SL_CPU)
#define SO_OBJECTS      (1 << SL_OBJECTS)
#define SO_TOTAL        (1 << SL_TOTAL)

static ssize_t show_slab_objects(struct kmem_cache *s,
                                 char *buf, unsigned long flags)
{
        unsigned long total = 0;
        int node;
        int x;
        unsigned long *nodes;
        int len = 0;

        nodes = kcalloc(nr_node_ids, sizeof(unsigned long), GFP_KERNEL);
        if (!nodes)
                return -ENOMEM;

        if (flags & SO_CPU) {
                int cpu;

                for_each_possible_cpu(cpu) {
                        struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab,
                                                               cpu);
                        int node;
                        struct slab *slab;

                        slab = READ_ONCE(c->slab);
                        if (!slab)
                                continue;

                        node = slab_nid(slab);
                        if (flags & SO_TOTAL)
                                x = slab->objects;
                        else if (flags & SO_OBJECTS)
                                x = slab->inuse;
                        else
                                x = 1;

                        total += x;
                        nodes[node] += x;

#ifdef CONFIG_SLUB_CPU_PARTIAL
                        slab = slub_percpu_partial_read_once(c);
                        if (slab) {
                                node = slab_nid(slab);
                                if (flags & SO_TOTAL)
                                        WARN_ON_ONCE(1);
                                else if (flags & SO_OBJECTS)
                                        WARN_ON_ONCE(1);
                                else
                                        x = slab->slabs;
                                total += x;
                                nodes[node] += x;
                        }
#endif
                }
        }

        /*
         * It is impossible to take "mem_hotplug_lock" here with "kernfs_mutex"
         * already held which will conflict with an existing lock order:
         *
         * mem_hotplug_lock->slab_mutex->kernfs_mutex
         *
         * We don't really need mem_hotplug_lock (to hold off
         * slab_mem_going_offline_callback) here because slab's memory hot
         * unplug code doesn't destroy the kmem_cache->node[] data.
         */

#ifdef CONFIG_SLUB_DEBUG
        if (flags & SO_ALL) {
                struct kmem_cache_node *n;

                for_each_kmem_cache_node(s, node, n) {

                        if (flags & SO_TOTAL)
                                x = atomic_long_read(&n->total_objects);
                        else if (flags & SO_OBJECTS)
                                x = atomic_long_read(&n->total_objects) -
                                        count_partial(n, count_free);
                        else
                                x = atomic_long_read(&n->nr_slabs);
                        total += x;
                        nodes[node] += x;
                }

        } else
#endif
        if (flags & SO_PARTIAL) {
                struct kmem_cache_node *n;

                for_each_kmem_cache_node(s, node, n) {
                        if (flags & SO_TOTAL)
                                x = count_partial(n, count_total);
                        else if (flags & SO_OBJECTS)
                                x = count_partial(n, count_inuse);
                        else
                                x = n->nr_partial;
                        total += x;
                        nodes[node] += x;
                }
        }

        len += sysfs_emit_at(buf, len, "%lu", total);
#ifdef CONFIG_NUMA
        for (node = 0; node < nr_node_ids; node++) {
                if (nodes[node])
                        len += sysfs_emit_at(buf, len, " N%d=%lu",
                                             node, nodes[node]);
        }
#endif
        len += sysfs_emit_at(buf, len, "\n");
        kfree(nodes);

        return len;
}

#define to_slab_attr(n) container_of(n, struct slab_attribute, attr)
#define to_slab(n) container_of(n, struct kmem_cache, kobj)

struct slab_attribute {
        struct attribute attr;
        ssize_t (*show)(struct kmem_cache *s, char *buf);
        ssize_t (*store)(struct kmem_cache *s, const char *x, size_t count);
};

#define SLAB_ATTR_RO(_name) \
        static struct slab_attribute _name##_attr = __ATTR_RO_MODE(_name, 0400)

#define SLAB_ATTR(_name) \
        static struct slab_attribute _name##_attr = __ATTR_RW_MODE(_name, 0600)

static ssize_t slab_size_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%u\n", s->size);
}
SLAB_ATTR_RO(slab_size);

static ssize_t align_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%u\n", s->align);
}
SLAB_ATTR_RO(align);

static ssize_t object_size_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%u\n", s->object_size);
}
SLAB_ATTR_RO(object_size);

static ssize_t objs_per_slab_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%u\n", oo_objects(s->oo));
}
SLAB_ATTR_RO(objs_per_slab);

static ssize_t order_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%u\n", oo_order(s->oo));
}
SLAB_ATTR_RO(order);

static ssize_t min_partial_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%lu\n", s->min_partial);
}

static ssize_t min_partial_store(struct kmem_cache *s, const char *buf,
                                 size_t length)
{
        unsigned long min;
        int err;

        err = kstrtoul(buf, 10, &min);
        if (err)
                return err;

        s->min_partial = min;
        return length;
}
SLAB_ATTR(min_partial);

static ssize_t cpu_partial_show(struct kmem_cache *s, char *buf)
{
        unsigned int nr_partial = 0;
#ifdef CONFIG_SLUB_CPU_PARTIAL
        nr_partial = s->cpu_partial;
#endif

        return sysfs_emit(buf, "%u\n", nr_partial);
}

static ssize_t cpu_partial_store(struct kmem_cache *s, const char *buf,
                                 size_t length)
{
        unsigned int objects;
        int err;

        err = kstrtouint(buf, 10, &objects);
        if (err)
                return err;
        if (objects && !kmem_cache_has_cpu_partial(s))
                return -EINVAL;

        slub_set_cpu_partial(s, objects);
        flush_all(s);
        return length;
}
SLAB_ATTR(cpu_partial);

static ssize_t ctor_show(struct kmem_cache *s, char *buf)
{
        if (!s->ctor)
                return 0;
        return sysfs_emit(buf, "%pS\n", s->ctor);
}
SLAB_ATTR_RO(ctor);

static ssize_t aliases_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%d\n", s->refcount < 0 ? 0 : s->refcount - 1);
}
SLAB_ATTR_RO(aliases);

static ssize_t partial_show(struct kmem_cache *s, char *buf)
{
        return show_slab_objects(s, buf, SO_PARTIAL);
}
SLAB_ATTR_RO(partial);

static ssize_t cpu_slabs_show(struct kmem_cache *s, char *buf)
{
        return show_slab_objects(s, buf, SO_CPU);
}
SLAB_ATTR_RO(cpu_slabs);

static ssize_t objects_show(struct kmem_cache *s, char *buf)
{
        return show_slab_objects(s, buf, SO_ALL|SO_OBJECTS);
}
SLAB_ATTR_RO(objects);

static ssize_t objects_partial_show(struct kmem_cache *s, char *buf)
{
        return show_slab_objects(s, buf, SO_PARTIAL|SO_OBJECTS);
}
SLAB_ATTR_RO(objects_partial);

static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
{
        int objects = 0;
        int slabs = 0;
        int cpu __maybe_unused;
        int len = 0;

#ifdef CONFIG_SLUB_CPU_PARTIAL
        for_each_online_cpu(cpu) {
                struct slab *slab;

                slab = slub_percpu_partial(per_cpu_ptr(s->cpu_slab, cpu));

                if (slab)
                        slabs += slab->slabs;
        }
#endif

        /* Approximate half-full slabs, see slub_set_cpu_partial() */
        objects = (slabs * oo_objects(s->oo)) / 2;
        len += sysfs_emit_at(buf, len, "%d(%d)", objects, slabs);

#if defined(CONFIG_SLUB_CPU_PARTIAL) && defined(CONFIG_SMP)
        for_each_online_cpu(cpu) {
                struct slab *slab;

                slab = slub_percpu_partial(per_cpu_ptr(s->cpu_slab, cpu));
                if (slab) {
                        slabs = READ_ONCE(slab->slabs);
                        objects = (slabs * oo_objects(s->oo)) / 2;
                        len += sysfs_emit_at(buf, len, " C%d=%d(%d)",
                                             cpu, objects, slabs);
                }
        }
#endif
        len += sysfs_emit_at(buf, len, "\n");

        return len;
}
SLAB_ATTR_RO(slabs_cpu_partial);

static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_RECLAIM_ACCOUNT));
}
SLAB_ATTR_RO(reclaim_account);

static ssize_t hwcache_align_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_HWCACHE_ALIGN));
}
SLAB_ATTR_RO(hwcache_align);

#ifdef CONFIG_ZONE_DMA
static ssize_t cache_dma_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_CACHE_DMA));
}
SLAB_ATTR_RO(cache_dma);
#endif

static ssize_t usersize_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%u\n", s->usersize);
}
SLAB_ATTR_RO(usersize);

static ssize_t destroy_by_rcu_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_TYPESAFE_BY_RCU));
}
SLAB_ATTR_RO(destroy_by_rcu);

#ifdef CONFIG_SLUB_DEBUG
static ssize_t slabs_show(struct kmem_cache *s, char *buf)
{
        return show_slab_objects(s, buf, SO_ALL);
}
SLAB_ATTR_RO(slabs);

static ssize_t total_objects_show(struct kmem_cache *s, char *buf)
{
        return show_slab_objects(s, buf, SO_ALL|SO_TOTAL);
}
SLAB_ATTR_RO(total_objects);

static ssize_t sanity_checks_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_CONSISTENCY_CHECKS));
}
SLAB_ATTR_RO(sanity_checks);

static ssize_t trace_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_TRACE));
}
SLAB_ATTR_RO(trace);

static ssize_t red_zone_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_RED_ZONE));
}

SLAB_ATTR_RO(red_zone);

static ssize_t poison_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_POISON));
}

SLAB_ATTR_RO(poison);

static ssize_t store_user_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_STORE_USER));
}

SLAB_ATTR_RO(store_user);

static ssize_t validate_show(struct kmem_cache *s, char *buf)
{
        return 0;
}

static ssize_t validate_store(struct kmem_cache *s,
                        const char *buf, size_t length)
{
        int ret = -EINVAL;

        if (buf[0] == '1' && kmem_cache_debug(s)) {
                ret = validate_slab_cache(s);
                if (ret >= 0)
                        ret = length;
        }
        return ret;
}
SLAB_ATTR(validate);

#endif /* CONFIG_SLUB_DEBUG */

#ifdef CONFIG_FAILSLAB
static ssize_t failslab_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_FAILSLAB));
}
SLAB_ATTR_RO(failslab);
#endif

static ssize_t shrink_show(struct kmem_cache *s, char *buf)
{
        return 0;
}

static ssize_t shrink_store(struct kmem_cache *s,
                        const char *buf, size_t length)
{
        if (buf[0] == '1')
                kmem_cache_shrink(s);
        else
                return -EINVAL;
        return length;
}
SLAB_ATTR(shrink);

#ifdef CONFIG_NUMA
static ssize_t remote_node_defrag_ratio_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%u\n", s->remote_node_defrag_ratio / 10);
}

static ssize_t remote_node_defrag_ratio_store(struct kmem_cache *s,
                                const char *buf, size_t length)
{
        unsigned int ratio;
        int err;

        err = kstrtouint(buf, 10, &ratio);
        if (err)
                return err;
        if (ratio > 100)
                return -ERANGE;

        s->remote_node_defrag_ratio = ratio * 10;

        return length;
}
SLAB_ATTR(remote_node_defrag_ratio);
#endif

#ifdef CONFIG_SLUB_STATS
static int show_stat(struct kmem_cache *s, char *buf, enum stat_item si)
{
        unsigned long sum  = 0;
        int cpu;
        int len = 0;
        int *data = kmalloc_array(nr_cpu_ids, sizeof(int), GFP_KERNEL);

        if (!data)
                return -ENOMEM;

        for_each_online_cpu(cpu) {
                unsigned x = per_cpu_ptr(s->cpu_slab, cpu)->stat[si];

                data[cpu] = x;
                sum += x;
        }

        len += sysfs_emit_at(buf, len, "%lu", sum);

#ifdef CONFIG_SMP
        for_each_online_cpu(cpu) {
                if (data[cpu])
                        len += sysfs_emit_at(buf, len, " C%d=%u",
                                             cpu, data[cpu]);
        }
#endif
        kfree(data);
        len += sysfs_emit_at(buf, len, "\n");

        return len;
}

static void clear_stat(struct kmem_cache *s, enum stat_item si)
{
        int cpu;

        for_each_online_cpu(cpu)
                per_cpu_ptr(s->cpu_slab, cpu)->stat[si] = 0;
}

#define STAT_ATTR(si, text)                                     \
static ssize_t text##_show(struct kmem_cache *s, char *buf)     \
{                                                               \
        return show_stat(s, buf, si);                           \
}                                                               \
static ssize_t text##_store(struct kmem_cache *s,               \
                                const char *buf, size_t length) \
{                                                               \
        if (buf[0] != '0')                                      \
                return -EINVAL;                                 \
        clear_stat(s, si);                                      \
        return length;                                          \
}                                                               \
SLAB_ATTR(text);                                                \

STAT_ATTR(ALLOC_FASTPATH, alloc_fastpath);
STAT_ATTR(ALLOC_SLOWPATH, alloc_slowpath);
STAT_ATTR(FREE_FASTPATH, free_fastpath);
STAT_ATTR(FREE_SLOWPATH, free_slowpath);
STAT_ATTR(FREE_FROZEN, free_frozen);
STAT_ATTR(FREE_ADD_PARTIAL, free_add_partial);
STAT_ATTR(FREE_REMOVE_PARTIAL, free_remove_partial);
STAT_ATTR(ALLOC_FROM_PARTIAL, alloc_from_partial);
STAT_ATTR(ALLOC_SLAB, alloc_slab);
STAT_ATTR(ALLOC_REFILL, alloc_refill);
STAT_ATTR(ALLOC_NODE_MISMATCH, alloc_node_mismatch);
STAT_ATTR(FREE_SLAB, free_slab);
STAT_ATTR(CPUSLAB_FLUSH, cpuslab_flush);
STAT_ATTR(DEACTIVATE_FULL, deactivate_full);
STAT_ATTR(DEACTIVATE_EMPTY, deactivate_empty);
STAT_ATTR(DEACTIVATE_TO_HEAD, deactivate_to_head);
STAT_ATTR(DEACTIVATE_TO_TAIL, deactivate_to_tail);
STAT_ATTR(DEACTIVATE_REMOTE_FREES, deactivate_remote_frees);
STAT_ATTR(DEACTIVATE_BYPASS, deactivate_bypass);
STAT_ATTR(ORDER_FALLBACK, order_fallback);
STAT_ATTR(CMPXCHG_DOUBLE_CPU_FAIL, cmpxchg_double_cpu_fail);
STAT_ATTR(CMPXCHG_DOUBLE_FAIL, cmpxchg_double_fail);
STAT_ATTR(CPU_PARTIAL_ALLOC, cpu_partial_alloc);
STAT_ATTR(CPU_PARTIAL_FREE, cpu_partial_free);
STAT_ATTR(CPU_PARTIAL_NODE, cpu_partial_node);
STAT_ATTR(CPU_PARTIAL_DRAIN, cpu_partial_drain);
#endif  /* CONFIG_SLUB_STATS */

#ifdef CONFIG_KFENCE
static ssize_t skip_kfence_show(struct kmem_cache *s, char *buf)
{
        return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_SKIP_KFENCE));
}

static ssize_t skip_kfence_store(struct kmem_cache *s,
                        const char *buf, size_t length)
{
        int ret = length;

        if (buf[0] == '0')
                s->flags &= ~SLAB_SKIP_KFENCE;
        else if (buf[0] == '1')
                s->flags |= SLAB_SKIP_KFENCE;
        else
                ret = -EINVAL;

        return ret;
}
SLAB_ATTR(skip_kfence);
#endif

static struct attribute *slab_attrs[] = {
        &slab_size_attr.attr,
        &object_size_attr.attr,
        &objs_per_slab_attr.attr,
        &order_attr.attr,
        &min_partial_attr.attr,
        &cpu_partial_attr.attr,
        &objects_attr.attr,
        &objects_partial_attr.attr,
        &partial_attr.attr,
        &cpu_slabs_attr.attr,
        &ctor_attr.attr,
        &aliases_attr.attr,
        &align_attr.attr,
        &hwcache_align_attr.attr,
        &reclaim_account_attr.attr,
        &destroy_by_rcu_attr.attr,
        &shrink_attr.attr,
        &slabs_cpu_partial_attr.attr,
#ifdef CONFIG_SLUB_DEBUG
        &total_objects_attr.attr,
        &slabs_attr.attr,
        &sanity_checks_attr.attr,
        &trace_attr.attr,
        &red_zone_attr.attr,
        &poison_attr.attr,
        &store_user_attr.attr,
        &validate_attr.attr,
#endif
#ifdef CONFIG_ZONE_DMA
        &cache_dma_attr.attr,
#endif
#ifdef CONFIG_NUMA
        &remote_node_defrag_ratio_attr.attr,
#endif
#ifdef CONFIG_SLUB_STATS
        &alloc_fastpath_attr.attr,
        &alloc_slowpath_attr.attr,
        &free_fastpath_attr.attr,
        &free_slowpath_attr.attr,
        &free_frozen_attr.attr,
        &free_add_partial_attr.attr,
        &free_remove_partial_attr.attr,
        &alloc_from_partial_attr.attr,
        &alloc_slab_attr.attr,
        &alloc_refill_attr.attr,
        &alloc_node_mismatch_attr.attr,
        &free_slab_attr.attr,
        &cpuslab_flush_attr.attr,
        &deactivate_full_attr.attr,
        &deactivate_empty_attr.attr,
        &deactivate_to_head_attr.attr,
        &deactivate_to_tail_attr.attr,
        &deactivate_remote_frees_attr.attr,
        &deactivate_bypass_attr.attr,
        &order_fallback_attr.attr,
        &cmpxchg_double_fail_attr.attr,
        &cmpxchg_double_cpu_fail_attr.attr,
        &cpu_partial_alloc_attr.attr,
        &cpu_partial_free_attr.attr,
        &cpu_partial_node_attr.attr,
        &cpu_partial_drain_attr.attr,
#endif
#ifdef CONFIG_FAILSLAB
        &failslab_attr.attr,
#endif
        &usersize_attr.attr,
#ifdef CONFIG_KFENCE
        &skip_kfence_attr.attr,
#endif

        NULL
};

static const struct attribute_group slab_attr_group = {
        .attrs = slab_attrs,
};

static ssize_t slab_attr_show(struct kobject *kobj,
                                struct attribute *attr,
                                char *buf)
{
        struct slab_attribute *attribute;
        struct kmem_cache *s;

        attribute = to_slab_attr(attr);
        s = to_slab(kobj);

        if (!attribute->show)
                return -EIO;

        return attribute->show(s, buf);
}

static ssize_t slab_attr_store(struct kobject *kobj,
                                struct attribute *attr,
                                const char *buf, size_t len)
{
        struct slab_attribute *attribute;
        struct kmem_cache *s;

        attribute = to_slab_attr(attr);
        s = to_slab(kobj);

        if (!attribute->store)
                return -EIO;

        return attribute->store(s, buf, len);
}

static void kmem_cache_release(struct kobject *k)
{
        slab_kmem_cache_release(to_slab(k));
}

static const struct sysfs_ops slab_sysfs_ops = {
        .show = slab_attr_show,
        .store = slab_attr_store,
};

static struct kobj_type slab_ktype = {
        .sysfs_ops = &slab_sysfs_ops,
        .release = kmem_cache_release,
};

static struct kset *slab_kset;

static inline struct kset *cache_kset(struct kmem_cache *s)
{
        return slab_kset;
}

#define ID_STR_LENGTH 32

/* Create a unique string id for a slab cache:
 *
 * Format       :[flags-]size
 */
static char *create_unique_id(struct kmem_cache *s)
{
        char *name = kmalloc(ID_STR_LENGTH, GFP_KERNEL);
        char *p = name;

        if (!name)
                return ERR_PTR(-ENOMEM);

        *p++ = ':';
        /*
         * First flags affecting slabcache operations. We will only
         * get here for aliasable slabs so we do not need to support
         * too many flags. The flags here must cover all flags that
         * are matched during merging to guarantee that the id is
         * unique.
         */
        if (s->flags & SLAB_CACHE_DMA)
                *p++ = 'd';
        if (s->flags & SLAB_CACHE_DMA32)
                *p++ = 'D';
        if (s->flags & SLAB_RECLAIM_ACCOUNT)
                *p++ = 'a';
        if (s->flags & SLAB_CONSISTENCY_CHECKS)
                *p++ = 'F';
        if (s->flags & SLAB_ACCOUNT)
                *p++ = 'A';
        if (p != name + 1)
                *p++ = '-';
        p += snprintf(p, ID_STR_LENGTH - (p - name), "%07u", s->size);

        if (WARN_ON(p > name + ID_STR_LENGTH - 1)) {
                kfree(name);
                return ERR_PTR(-EINVAL);
        }
        kmsan_unpoison_memory(name, p - name);
        return name;
}

static int sysfs_slab_add(struct kmem_cache *s)
{
        int err;
        const char *name;
        struct kset *kset = cache_kset(s);
        int unmergeable = slab_unmergeable(s);

        if (!kset) {
                kobject_init(&s->kobj, &slab_ktype);
                return 0;
        }

        if (!unmergeable && disable_higher_order_debug &&
                        (slub_debug & DEBUG_METADATA_FLAGS))
                unmergeable = 1;

        if (unmergeable) {
                /*
                 * Slabcache can never be merged so we can use the name proper.
                 * This is typically the case for debug situations. In that
                 * case we can catch duplicate names easily.
                 */
                sysfs_remove_link(&slab_kset->kobj, s->name);
                name = s->name;
        } else {
                /*
                 * Create a unique name for the slab as a target
                 * for the symlinks.
                 */
                name = create_unique_id(s);
                if (IS_ERR(name))
                        return PTR_ERR(name);
        }

        s->kobj.kset = kset;
        err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name);
        if (err)
                goto out;

        err = sysfs_create_group(&s->kobj, &slab_attr_group);
        if (err)
                goto out_del_kobj;

        if (!unmergeable) {
                /* Setup first alias */
                sysfs_slab_alias(s, s->name);
        }
out:
        if (!unmergeable)
                kfree(name);
        return err;
out_del_kobj:
        kobject_del(&s->kobj);
        goto out;
}

void sysfs_slab_unlink(struct kmem_cache *s)
{
        if (slab_state >= FULL)
                kobject_del(&s->kobj);
}

void sysfs_slab_release(struct kmem_cache *s)
{
        if (slab_state >= FULL)
                kobject_put(&s->kobj);
}

/*
 * Need to buffer aliases during bootup until sysfs becomes
 * available lest we lose that information.
 */
struct saved_alias {
        struct kmem_cache *s;
        const char *name;
        struct saved_alias *next;
};

static struct saved_alias *alias_list;

static int sysfs_slab_alias(struct kmem_cache *s, const char *name)
{
        struct saved_alias *al;

        if (slab_state == FULL) {
                /*
                 * If we have a leftover link then remove it.
                 */
                sysfs_remove_link(&slab_kset->kobj, name);
                return sysfs_create_link(&slab_kset->kobj, &s->kobj, name);
        }

        al = kmalloc(sizeof(struct saved_alias), GFP_KERNEL);
        if (!al)
                return -ENOMEM;

        al->s = s;
        al->name = name;
        al->next = alias_list;
        alias_list = al;
        kmsan_unpoison_memory(al, sizeof(*al));
        return 0;
}

static int __init slab_sysfs_init(void)
{
        struct kmem_cache *s;
        int err;

        mutex_lock(&slab_mutex);

        slab_kset = kset_create_and_add("slab", NULL, kernel_kobj);
        if (!slab_kset) {
                mutex_unlock(&slab_mutex);
                pr_err("Cannot register slab subsystem.\n");
                return -ENOSYS;
        }

        slab_state = FULL;

        list_for_each_entry(s, &slab_caches, list) {
                err = sysfs_slab_add(s);
                if (err)
                        pr_err("SLUB: Unable to add boot slab %s to sysfs\n",
                               s->name);
        }

        while (alias_list) {
                struct saved_alias *al = alias_list;

                alias_list = alias_list->next;
                err = sysfs_slab_alias(al->s, al->name);
                if (err)
                        pr_err("SLUB: Unable to add boot slab alias %s to sysfs\n",
                               al->name);
                kfree(al);
        }

        mutex_unlock(&slab_mutex);
        return 0;
}

__initcall(slab_sysfs_init);
#endif /* CONFIG_SYSFS */

#if defined(CONFIG_SLUB_DEBUG) && defined(CONFIG_DEBUG_FS)
static int slab_debugfs_show(struct seq_file *seq, void *v)
{
        struct loc_track *t = seq->private;
        struct location *l;
        unsigned long idx;

        idx = (unsigned long) t->idx;
        if (idx < t->count) {
                l = &t->loc[idx];

                seq_printf(seq, "%7ld ", l->count);

                if (l->addr)
                        seq_printf(seq, "%pS", (void *)l->addr);
                else
                        seq_puts(seq, "<not-available>");

                if (l->waste)
                        seq_printf(seq, " waste=%lu/%lu",
                                l->count * l->waste, l->waste);

                if (l->sum_time != l->min_time) {
                        seq_printf(seq, " age=%ld/%llu/%ld",
                                l->min_time, div_u64(l->sum_time, l->count),
                                l->max_time);
                } else
                        seq_printf(seq, " age=%ld", l->min_time);

                if (l->min_pid != l->max_pid)
                        seq_printf(seq, " pid=%ld-%ld", l->min_pid, l->max_pid);
                else
                        seq_printf(seq, " pid=%ld",
                                l->min_pid);

                if (num_online_cpus() > 1 && !cpumask_empty(to_cpumask(l->cpus)))
                        seq_printf(seq, " cpus=%*pbl",
                                 cpumask_pr_args(to_cpumask(l->cpus)));

                if (nr_online_nodes > 1 && !nodes_empty(l->nodes))
                        seq_printf(seq, " nodes=%*pbl",
                                 nodemask_pr_args(&l->nodes));

#ifdef CONFIG_STACKDEPOT
                {
                        depot_stack_handle_t handle;
                        unsigned long *entries;
                        unsigned int nr_entries, j;

                        handle = READ_ONCE(l->handle);
                        if (handle) {
                                nr_entries = stack_depot_fetch(handle, &entries);
                                seq_puts(seq, "\n");
                                for (j = 0; j < nr_entries; j++)
                                        seq_printf(seq, "        %pS\n", (void *)entries[j]);
                        }
                }
#endif
                seq_puts(seq, "\n");
        }

        if (!idx && !t->count)
                seq_puts(seq, "No data\n");

        return 0;
}

static void slab_debugfs_stop(struct seq_file *seq, void *v)
{
}

static void *slab_debugfs_next(struct seq_file *seq, void *v, loff_t *ppos)
{
        struct loc_track *t = seq->private;

        t->idx = ++(*ppos);
        if (*ppos <= t->count)
                return ppos;

        return NULL;
}

static int cmp_loc_by_count(const void *a, const void *b, const void *data)
{
        struct location *loc1 = (struct location *)a;
        struct location *loc2 = (struct location *)b;

        if (loc1->count > loc2->count)
                return -1;
        else
                return 1;
}

static void *slab_debugfs_start(struct seq_file *seq, loff_t *ppos)
{
        struct loc_track *t = seq->private;

        t->idx = *ppos;
        return ppos;
}

static const struct seq_operations slab_debugfs_sops = {
        .start  = slab_debugfs_start,
        .next   = slab_debugfs_next,
        .stop   = slab_debugfs_stop,
        .show   = slab_debugfs_show,
};

static int slab_debug_trace_open(struct inode *inode, struct file *filep)
{

        struct kmem_cache_node *n;
        enum track_item alloc;
        int node;
        struct loc_track *t = __seq_open_private(filep, &slab_debugfs_sops,
                                                sizeof(struct loc_track));
        struct kmem_cache *s = file_inode(filep)->i_private;
        unsigned long *obj_map;

        if (!t)
                return -ENOMEM;

        obj_map = bitmap_alloc(oo_objects(s->oo), GFP_KERNEL);
        if (!obj_map) {
                seq_release_private(inode, filep);
                return -ENOMEM;
        }

        if (strcmp(filep->f_path.dentry->d_name.name, "alloc_traces") == 0)
                alloc = TRACK_ALLOC;
        else
                alloc = TRACK_FREE;

        if (!alloc_loc_track(t, PAGE_SIZE / sizeof(struct location), GFP_KERNEL)) {
                bitmap_free(obj_map);
                seq_release_private(inode, filep);
                return -ENOMEM;
        }

        for_each_kmem_cache_node(s, node, n) {
                unsigned long flags;
                struct slab *slab;

                if (!atomic_long_read(&n->nr_slabs))
                        continue;

                spin_lock_irqsave(&n->list_lock, flags);
                list_for_each_entry(slab, &n->partial, slab_list)
                        process_slab(t, s, slab, alloc, obj_map);
                list_for_each_entry(slab, &n->full, slab_list)
                        process_slab(t, s, slab, alloc, obj_map);
                spin_unlock_irqrestore(&n->list_lock, flags);
        }

        /* Sort locations by count */
        sort_r(t->loc, t->count, sizeof(struct location),
                cmp_loc_by_count, NULL, NULL);

        bitmap_free(obj_map);
        return 0;
}

static int slab_debug_trace_release(struct inode *inode, struct file *file)
{
        struct seq_file *seq = file->private_data;
        struct loc_track *t = seq->private;

        free_loc_track(t);
        return seq_release_private(inode, file);
}

static const struct file_operations slab_debugfs_fops = {
        .open    = slab_debug_trace_open,
        .read    = seq_read,
        .llseek  = seq_lseek,
        .release = slab_debug_trace_release,
};

static void debugfs_slab_add(struct kmem_cache *s)
{
        struct dentry *slab_cache_dir;

        if (unlikely(!slab_debugfs_root))
                return;

        slab_cache_dir = debugfs_create_dir(s->name, slab_debugfs_root);

        debugfs_create_file("alloc_traces", 0400,
                slab_cache_dir, s, &slab_debugfs_fops);

        debugfs_create_file("free_traces", 0400,
                slab_cache_dir, s, &slab_debugfs_fops);
}

void debugfs_slab_release(struct kmem_cache *s)
{
        debugfs_remove_recursive(debugfs_lookup(s->name, slab_debugfs_root));
}

static int __init slab_debugfs_init(void)
{
        struct kmem_cache *s;

        slab_debugfs_root = debugfs_create_dir("slab", NULL);

        list_for_each_entry(s, &slab_caches, list)
                if (s->flags & SLAB_STORE_USER)
                        debugfs_slab_add(s);

        return 0;

}
__initcall(slab_debugfs_init);
#endif
/*
 * The /proc/slabinfo ABI
 */
#ifdef CONFIG_SLUB_DEBUG
void get_slabinfo(struct kmem_cache *s, struct slabinfo *sinfo)
{
        unsigned long nr_slabs = 0;
        unsigned long nr_objs = 0;
        unsigned long nr_free = 0;
        int node;
        struct kmem_cache_node *n;

        for_each_kmem_cache_node(s, node, n) {
                nr_slabs += node_nr_slabs(n);
                nr_objs += node_nr_objs(n);
                nr_free += count_partial(n, count_free);
        }

        sinfo->active_objs = nr_objs - nr_free;
        sinfo->num_objs = nr_objs;
        sinfo->active_slabs = nr_slabs;
        sinfo->num_slabs = nr_slabs;
        sinfo->objects_per_slab = oo_objects(s->oo);
        sinfo->cache_order = oo_order(s->oo);
}

void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s)
{
}

ssize_t slabinfo_write(struct file *file, const char __user *buffer,
                       size_t count, loff_t *ppos)
{
        return -EIO;
}
#endif /* CONFIG_SLUB_DEBUG */