[thirdparty/linux.git] / mm / slab_common.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Slab allocator functions that are independent of the allocator strategy
 *
 * (C) 2012 Christoph Lameter <cl@gentwo.org>
 */
#include <linux/slab.h>

#include <linux/mm.h>
#include <linux/poison.h>
#include <linux/interrupt.h>
#include <linux/memory.h>
#include <linux/cache.h>
#include <linux/compiler.h>
#include <linux/kfence.h>
#include <linux/module.h>
#include <linux/cpu.h>
#include <linux/uaccess.h>
#include <linux/seq_file.h>
#include <linux/dma-mapping.h>
#include <linux/swiotlb.h>
#include <linux/proc_fs.h>
#include <linux/debugfs.h>
#include <linux/kmemleak.h>
#include <linux/kasan.h>
#include <asm/cacheflush.h>
#include <asm/tlbflush.h>
#include <asm/page.h>
#include <linux/memcontrol.h>
#include <linux/stackdepot.h>
#include <trace/events/rcu.h>

#include "../kernel/rcu/rcu.h"
#include "internal.h"
#include "slab.h"

#define CREATE_TRACE_POINTS
#include <trace/events/kmem.h>

enum slab_state slab_state;
LIST_HEAD(slab_caches);
DEFINE_MUTEX(slab_mutex);
struct kmem_cache *kmem_cache;

/*
 * Set of flags that will prevent slab merging
 */
#define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
                SLAB_TRACE | SLAB_TYPESAFE_BY_RCU | SLAB_NOLEAKTRACE | \
                SLAB_FAILSLAB | SLAB_NO_MERGE)

#define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
                         SLAB_CACHE_DMA32 | SLAB_ACCOUNT)

/*
 * Merge control. If this is set then no merging of slab caches will occur.
 */
static bool slab_nomerge = !IS_ENABLED(CONFIG_SLAB_MERGE_DEFAULT);

static int __init setup_slab_nomerge(char *str)
{
        slab_nomerge = true;
        return 1;
}

static int __init setup_slab_merge(char *str)
{
        slab_nomerge = false;
        return 1;
}

__setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0);
__setup_param("slub_merge", slub_merge, setup_slab_merge, 0);

__setup("slab_nomerge", setup_slab_nomerge);
__setup("slab_merge", setup_slab_merge);

/*
 * Determine the size of a slab object
 */
unsigned int kmem_cache_size(struct kmem_cache *s)
{
        return s->object_size;
}
EXPORT_SYMBOL(kmem_cache_size);

#ifdef CONFIG_DEBUG_VM

static bool kmem_cache_is_duplicate_name(const char *name)
{
        struct kmem_cache *s;

        list_for_each_entry(s, &slab_caches, list) {
                if (!strcmp(s->name, name))
                        return true;
        }

        return false;
}

static int kmem_cache_sanity_check(const char *name, unsigned int size)
{
        if (!name || in_interrupt() || size > KMALLOC_MAX_SIZE) {
                pr_err("kmem_cache_create(%s) integrity check failed\n", name);
                return -EINVAL;
        }

        /* Duplicate names will confuse slabtop, et al */
        WARN(kmem_cache_is_duplicate_name(name),
                        "kmem_cache of name '%s' already exists\n", name);

        WARN_ON(strchr(name, ' '));     /* It confuses parsers */
        return 0;
}
#else
static inline int kmem_cache_sanity_check(const char *name, unsigned int size)
{
        return 0;
}
#endif

/*
 * Figure out what the alignment of the objects will be given a set of
 * flags, a user specified alignment and the size of the objects.
 */
static unsigned int calculate_alignment(slab_flags_t flags,
                unsigned int align, unsigned int size)
{
        /*
         * If the user wants hardware cache aligned objects then follow that
         * suggestion if the object is sufficiently large.
         *
         * The hardware cache alignment cannot override the specified
         * alignment though. If that is greater then use it.
         */
        if (flags & SLAB_HWCACHE_ALIGN) {
                unsigned int ralign;

                ralign = cache_line_size();
                while (size <= ralign / 2)
                        ralign /= 2;
                align = max(align, ralign);
        }

        align = max(align, arch_slab_minalign());

        return ALIGN(align, sizeof(void *));
}

/*
 * Find a mergeable slab cache
 */
int slab_unmergeable(struct kmem_cache *s)
{
        if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE))
                return 1;

        if (s->ctor)
                return 1;

#ifdef CONFIG_HARDENED_USERCOPY
        if (s->usersize)
                return 1;
#endif

        /*
         * We may have set a slab to be unmergeable during bootstrap.
         */
        if (s->refcount < 0)
                return 1;

        return 0;
}

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

        if (slab_nomerge)
                return NULL;

        if (ctor)
                return NULL;

        flags = kmem_cache_flags(flags, name);

        if (flags & SLAB_NEVER_MERGE)
                return NULL;

        size = ALIGN(size, sizeof(void *));
        align = calculate_alignment(flags, align, size);
        size = ALIGN(size, align);

        list_for_each_entry_reverse(s, &slab_caches, list) {
                if (slab_unmergeable(s))
                        continue;

                if (size > s->size)
                        continue;

                if ((flags & SLAB_MERGE_SAME) != (s->flags & SLAB_MERGE_SAME))
                        continue;
                /*
                 * Check if alignment is compatible.
                 * Courtesy of Adrian Drzewiecki
                 */
                if ((s->size & ~(align - 1)) != s->size)
                        continue;

                if (s->size - size >= sizeof(void *))
                        continue;

                return s;
        }
        return NULL;
}

static struct kmem_cache *create_cache(const char *name,
                                       unsigned int object_size,
                                       struct kmem_cache_args *args,
                                       slab_flags_t flags)
{
        struct kmem_cache *s;
        int err;

        /* If a custom freelist pointer is requested make sure it's sane. */
        err = -EINVAL;
        if (args->use_freeptr_offset &&
            (args->freeptr_offset >= object_size ||
             !(flags & SLAB_TYPESAFE_BY_RCU) ||
             !IS_ALIGNED(args->freeptr_offset, __alignof__(freeptr_t))))
                goto out;

        err = -ENOMEM;
        s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
        if (!s)
                goto out;
        err = do_kmem_cache_create(s, name, object_size, args, flags);
        if (err)
                goto out_free_cache;

        s->refcount = 1;
        list_add(&s->list, &slab_caches);
        return s;

out_free_cache:
        kmem_cache_free(kmem_cache, s);
out:
        return ERR_PTR(err);
}

/**
 * __kmem_cache_create_args - Create a kmem cache.
 * @name: A string which is used in /proc/slabinfo to identify this cache.
 * @object_size: The size of objects to be created in this cache.
 * @args: Additional arguments for the cache creation (see
 *        &struct kmem_cache_args).
 * @flags: See the desriptions of individual flags. The common ones are listed
 *         in the description below.
 *
 * Not to be called directly, use the kmem_cache_create() wrapper with the same
 * parameters.
 *
 * Commonly used @flags:
 *
 * &SLAB_ACCOUNT - Account allocations to memcg.
 *
 * &SLAB_HWCACHE_ALIGN - Align objects on cache line boundaries.
 *
 * &SLAB_RECLAIM_ACCOUNT - Objects are reclaimable.
 *
 * &SLAB_TYPESAFE_BY_RCU - Slab page (not individual objects) freeing delayed
 * by a grace period - see the full description before using.
 *
 * Context: Cannot be called within a interrupt, but can be interrupted.
 *
 * Return: a pointer to the cache on success, NULL on failure.
 */
struct kmem_cache *__kmem_cache_create_args(const char *name,
                                            unsigned int object_size,
                                            struct kmem_cache_args *args,
                                            slab_flags_t flags)
{
        struct kmem_cache *s = NULL;
        const char *cache_name;
        int err;

#ifdef CONFIG_SLUB_DEBUG
        /*
         * If no slab_debug was enabled globally, the static key is not yet
         * enabled by setup_slub_debug(). Enable it if the cache is being
         * created with any of the debugging flags passed explicitly.
         * It's also possible that this is the first cache created with
         * SLAB_STORE_USER and we should init stack_depot for it.
         */
        if (flags & SLAB_DEBUG_FLAGS)
                static_branch_enable(&slub_debug_enabled);
        if (flags & SLAB_STORE_USER)
                stack_depot_init();
#else
        flags &= ~SLAB_DEBUG_FLAGS;
#endif

        mutex_lock(&slab_mutex);

        err = kmem_cache_sanity_check(name, object_size);
        if (err) {
                goto out_unlock;
        }

        if (flags & ~SLAB_FLAGS_PERMITTED) {
                err = -EINVAL;
                goto out_unlock;
        }

        /* Fail closed on bad usersize of useroffset values. */
        if (!IS_ENABLED(CONFIG_HARDENED_USERCOPY) ||
            WARN_ON(!args->usersize && args->useroffset) ||
            WARN_ON(object_size < args->usersize ||
                    object_size - args->usersize < args->useroffset))
                args->usersize = args->useroffset = 0;

        if (!args->usersize)
                s = __kmem_cache_alias(name, object_size, args->align, flags,
                                       args->ctor);
        if (s)
                goto out_unlock;

        cache_name = kstrdup_const(name, GFP_KERNEL);
        if (!cache_name) {
                err = -ENOMEM;
                goto out_unlock;
        }

        args->align = calculate_alignment(flags, args->align, object_size);
        s = create_cache(cache_name, object_size, args, flags);
        if (IS_ERR(s)) {
                err = PTR_ERR(s);
                kfree_const(cache_name);
        }

out_unlock:
        mutex_unlock(&slab_mutex);

        if (err) {
                if (flags & SLAB_PANIC)
                        panic("%s: Failed to create slab '%s'. Error %d\n",
                                __func__, name, err);
                else {
                        pr_warn("%s(%s) failed with error %d\n",
                                __func__, name, err);
                        dump_stack();
                }
                return NULL;
        }
        return s;
}
EXPORT_SYMBOL(__kmem_cache_create_args);

static struct kmem_cache *kmem_buckets_cache __ro_after_init;

/**
 * kmem_buckets_create - Create a set of caches that handle dynamic sized
 *                       allocations via kmem_buckets_alloc()
 * @name: A prefix string which is used in /proc/slabinfo to identify this
 *        cache. The individual caches with have their sizes as the suffix.
 * @flags: SLAB flags (see kmem_cache_create() for details).
 * @useroffset: Starting offset within an allocation that may be copied
 *              to/from userspace.
 * @usersize: How many bytes, starting at @useroffset, may be copied
 *              to/from userspace.
 * @ctor: A constructor for the objects, run when new allocations are made.
 *
 * Cannot be called within an interrupt, but can be interrupted.
 *
 * Return: a pointer to the cache on success, NULL on failure. When
 * CONFIG_SLAB_BUCKETS is not enabled, ZERO_SIZE_PTR is returned, and
 * subsequent calls to kmem_buckets_alloc() will fall back to kmalloc().
 * (i.e. callers only need to check for NULL on failure.)
 */
kmem_buckets *kmem_buckets_create(const char *name, slab_flags_t flags,
                                  unsigned int useroffset,
                                  unsigned int usersize,
                                  void (*ctor)(void *))
{
        unsigned long mask = 0;
        unsigned int idx;
        kmem_buckets *b;

        BUILD_BUG_ON(ARRAY_SIZE(kmalloc_caches[KMALLOC_NORMAL]) > BITS_PER_LONG);

        /*
         * When the separate buckets API is not built in, just return
         * a non-NULL value for the kmem_buckets pointer, which will be
         * unused when performing allocations.
         */
        if (!IS_ENABLED(CONFIG_SLAB_BUCKETS))
                return ZERO_SIZE_PTR;

        if (WARN_ON(!kmem_buckets_cache))
                return NULL;

        b = kmem_cache_alloc(kmem_buckets_cache, GFP_KERNEL|__GFP_ZERO);
        if (WARN_ON(!b))
                return NULL;

        flags |= SLAB_NO_MERGE;

        for (idx = 0; idx < ARRAY_SIZE(kmalloc_caches[KMALLOC_NORMAL]); idx++) {
                char *short_size, *cache_name;
                unsigned int cache_useroffset, cache_usersize;
                unsigned int size, aligned_idx;

                if (!kmalloc_caches[KMALLOC_NORMAL][idx])
                        continue;

                size = kmalloc_caches[KMALLOC_NORMAL][idx]->object_size;
                if (!size)
                        continue;

                short_size = strchr(kmalloc_caches[KMALLOC_NORMAL][idx]->name, '-');
                if (WARN_ON(!short_size))
                        goto fail;

                if (useroffset >= size) {
                        cache_useroffset = 0;
                        cache_usersize = 0;
                } else {
                        cache_useroffset = useroffset;
                        cache_usersize = min(size - cache_useroffset, usersize);
                }

                aligned_idx = __kmalloc_index(size, false);
                if (!(*b)[aligned_idx]) {
                        cache_name = kasprintf(GFP_KERNEL, "%s-%s", name, short_size + 1);
                        if (WARN_ON(!cache_name))
                                goto fail;
                        (*b)[aligned_idx] = kmem_cache_create_usercopy(cache_name, size,
                                        0, flags, cache_useroffset,
                                        cache_usersize, ctor);
                        kfree(cache_name);
                        if (WARN_ON(!(*b)[aligned_idx]))
                                goto fail;
                        set_bit(aligned_idx, &mask);
                }
                if (idx != aligned_idx)
                        (*b)[idx] = (*b)[aligned_idx];
        }

        return b;

fail:
        for_each_set_bit(idx, &mask, ARRAY_SIZE(kmalloc_caches[KMALLOC_NORMAL]))
                kmem_cache_destroy((*b)[idx]);
        kmem_cache_free(kmem_buckets_cache, b);

        return NULL;
}
EXPORT_SYMBOL(kmem_buckets_create);

/*
 * For a given kmem_cache, kmem_cache_destroy() should only be called
 * once or there will be a use-after-free problem. The actual deletion
 * and release of the kobject does not need slab_mutex or cpu_hotplug_lock
 * protection. So they are now done without holding those locks.
 */
static void kmem_cache_release(struct kmem_cache *s)
{
        kfence_shutdown_cache(s);
        if (__is_defined(SLAB_SUPPORTS_SYSFS) && slab_state >= FULL)
                sysfs_slab_release(s);
        else
                slab_kmem_cache_release(s);
}

void slab_kmem_cache_release(struct kmem_cache *s)
{
        __kmem_cache_release(s);
        kfree_const(s->name);
        kmem_cache_free(kmem_cache, s);
}

void kmem_cache_destroy(struct kmem_cache *s)
{
        int err;

        if (unlikely(!s) || !kasan_check_byte(s))
                return;

        /* in-flight kfree_rcu()'s may include objects from our cache */
        kvfree_rcu_barrier();

        if (IS_ENABLED(CONFIG_SLUB_RCU_DEBUG) &&
            (s->flags & SLAB_TYPESAFE_BY_RCU)) {
                /*
                 * Under CONFIG_SLUB_RCU_DEBUG, when objects in a
                 * SLAB_TYPESAFE_BY_RCU slab are freed, SLUB will internally
                 * defer their freeing with call_rcu().
                 * Wait for such call_rcu() invocations here before actually
                 * destroying the cache.
                 *
                 * It doesn't matter that we haven't looked at the slab refcount
                 * yet - slabs with SLAB_TYPESAFE_BY_RCU can't be merged, so
                 * the refcount should be 1 here.
                 */
                rcu_barrier();
        }

        cpus_read_lock();
        mutex_lock(&slab_mutex);

        s->refcount--;
        if (s->refcount) {
                mutex_unlock(&slab_mutex);
                cpus_read_unlock();
                return;
        }

        /* free asan quarantined objects */
        kasan_cache_shutdown(s);

        err = __kmem_cache_shutdown(s);
        if (!slab_in_kunit_test())
                WARN(err, "%s %s: Slab cache still has objects when called from %pS",
                     __func__, s->name, (void *)_RET_IP_);

        list_del(&s->list);

        mutex_unlock(&slab_mutex);
        cpus_read_unlock();

        if (slab_state >= FULL)
                sysfs_slab_unlink(s);
        debugfs_slab_release(s);

        if (err)
                return;

        if (s->flags & SLAB_TYPESAFE_BY_RCU)
                rcu_barrier();

        kmem_cache_release(s);
}
EXPORT_SYMBOL(kmem_cache_destroy);

/**
 * kmem_cache_shrink - Shrink a cache.
 * @cachep: The cache to shrink.
 *
 * Releases as many slabs as possible for a cache.
 * To help debugging, a zero exit status indicates all slabs were released.
 *
 * Return: %0 if all slabs were released, non-zero otherwise
 */
int kmem_cache_shrink(struct kmem_cache *cachep)
{
        kasan_cache_shrink(cachep);

        return __kmem_cache_shrink(cachep);
}
EXPORT_SYMBOL(kmem_cache_shrink);

bool slab_is_available(void)
{
        return slab_state >= UP;
}

#ifdef CONFIG_PRINTK
static void kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab)
{
        if (__kfence_obj_info(kpp, object, slab))
                return;
        __kmem_obj_info(kpp, object, slab);
}

/**
 * kmem_dump_obj - Print available slab provenance information
 * @object: slab object for which to find provenance information.
 *
 * This function uses pr_cont(), so that the caller is expected to have
 * printed out whatever preamble is appropriate.  The provenance information
 * depends on the type of object and on how much debugging is enabled.
 * For a slab-cache object, the fact that it is a slab object is printed,
 * and, if available, the slab name, return address, and stack trace from
 * the allocation and last free path of that object.
 *
 * Return: %true if the pointer is to a not-yet-freed object from
 * kmalloc() or kmem_cache_alloc(), either %true or %false if the pointer
 * is to an already-freed object, and %false otherwise.
 */
bool kmem_dump_obj(void *object)
{
        char *cp = IS_ENABLED(CONFIG_MMU) ? "" : "/vmalloc";
        int i;
        struct slab *slab;
        unsigned long ptroffset;
        struct kmem_obj_info kp = { };

        /* Some arches consider ZERO_SIZE_PTR to be a valid address. */
        if (object < (void *)PAGE_SIZE || !virt_addr_valid(object))
                return false;
        slab = virt_to_slab(object);
        if (!slab)
                return false;

        kmem_obj_info(&kp, object, slab);
        if (kp.kp_slab_cache)
                pr_cont(" slab%s %s", cp, kp.kp_slab_cache->name);
        else
                pr_cont(" slab%s", cp);
        if (is_kfence_address(object))
                pr_cont(" (kfence)");
        if (kp.kp_objp)
                pr_cont(" start %px", kp.kp_objp);
        if (kp.kp_data_offset)
                pr_cont(" data offset %lu", kp.kp_data_offset);
        if (kp.kp_objp) {
                ptroffset = ((char *)object - (char *)kp.kp_objp) - kp.kp_data_offset;
                pr_cont(" pointer offset %lu", ptroffset);
        }
        if (kp.kp_slab_cache && kp.kp_slab_cache->object_size)
                pr_cont(" size %u", kp.kp_slab_cache->object_size);
        if (kp.kp_ret)
                pr_cont(" allocated at %pS\n", kp.kp_ret);
        else
                pr_cont("\n");
        for (i = 0; i < ARRAY_SIZE(kp.kp_stack); i++) {
                if (!kp.kp_stack[i])
                        break;
                pr_info("    %pS\n", kp.kp_stack[i]);
        }

        if (kp.kp_free_stack[0])
                pr_cont(" Free path:\n");

        for (i = 0; i < ARRAY_SIZE(kp.kp_free_stack); i++) {
                if (!kp.kp_free_stack[i])
                        break;
                pr_info("    %pS\n", kp.kp_free_stack[i]);
        }

        return true;
}
EXPORT_SYMBOL_GPL(kmem_dump_obj);
#endif

/* Create a cache during boot when no slab services are available yet */
void __init create_boot_cache(struct kmem_cache *s, const char *name,
                unsigned int size, slab_flags_t flags,
                unsigned int useroffset, unsigned int usersize)
{
        int err;
        unsigned int align = ARCH_KMALLOC_MINALIGN;
        struct kmem_cache_args kmem_args = {};

        /*
         * kmalloc caches guarantee alignment of at least the largest
         * power-of-two divisor of the size. For power-of-two sizes,
         * it is the size itself.
         */
        if (flags & SLAB_KMALLOC)
                align = max(align, 1U << (ffs(size) - 1));
        kmem_args.align = calculate_alignment(flags, align, size);

#ifdef CONFIG_HARDENED_USERCOPY
        kmem_args.useroffset = useroffset;
        kmem_args.usersize = usersize;
#endif

        err = do_kmem_cache_create(s, name, size, &kmem_args, flags);

        if (err)
                panic("Creation of kmalloc slab %s size=%u failed. Reason %d\n",
                                        name, size, err);

        s->refcount = -1;       /* Exempt from merging for now */
}

static struct kmem_cache *__init create_kmalloc_cache(const char *name,
                                                      unsigned int size,
                                                      slab_flags_t flags)
{
        struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);

        if (!s)
                panic("Out of memory when creating slab %s\n", name);

        create_boot_cache(s, name, size, flags | SLAB_KMALLOC, 0, size);
        list_add(&s->list, &slab_caches);
        s->refcount = 1;
        return s;
}

kmem_buckets kmalloc_caches[NR_KMALLOC_TYPES] __ro_after_init =
{ /* initialization for https://llvm.org/pr42570 */ };
EXPORT_SYMBOL(kmalloc_caches);

#ifdef CONFIG_RANDOM_KMALLOC_CACHES
unsigned long random_kmalloc_seed __ro_after_init;
EXPORT_SYMBOL(random_kmalloc_seed);
#endif

/*
 * Conversion table for small slabs sizes / 8 to the index in the
 * kmalloc array. This is necessary for slabs < 192 since we have non power
 * of two cache sizes there. The size of larger slabs can be determined using
 * fls.
 */
u8 kmalloc_size_index[24] __ro_after_init = {
        3,      /* 8 */
        4,      /* 16 */
        5,      /* 24 */
        5,      /* 32 */
        6,      /* 40 */
        6,      /* 48 */
        6,      /* 56 */
        6,      /* 64 */
        1,      /* 72 */
        1,      /* 80 */
        1,      /* 88 */
        1,      /* 96 */
        7,      /* 104 */
        7,      /* 112 */
        7,      /* 120 */
        7,      /* 128 */
        2,      /* 136 */
        2,      /* 144 */
        2,      /* 152 */
        2,      /* 160 */
        2,      /* 168 */
        2,      /* 176 */
        2,      /* 184 */
        2       /* 192 */
};

size_t kmalloc_size_roundup(size_t size)
{
        if (size && size <= KMALLOC_MAX_CACHE_SIZE) {
                /*
                 * The flags don't matter since size_index is common to all.
                 * Neither does the caller for just getting ->object_size.
                 */
                return kmalloc_slab(size, NULL, GFP_KERNEL, 0)->object_size;
        }

        /* Above the smaller buckets, size is a multiple of page size. */
        if (size && size <= KMALLOC_MAX_SIZE)
                return PAGE_SIZE << get_order(size);

        /*
         * Return 'size' for 0 - kmalloc() returns ZERO_SIZE_PTR
         * and very large size - kmalloc() may fail.
         */
        return size;

}
EXPORT_SYMBOL(kmalloc_size_roundup);

#ifdef CONFIG_ZONE_DMA
#define KMALLOC_DMA_NAME(sz)    .name[KMALLOC_DMA] = "dma-kmalloc-" #sz,
#else
#define KMALLOC_DMA_NAME(sz)
#endif

#ifdef CONFIG_MEMCG
#define KMALLOC_CGROUP_NAME(sz) .name[KMALLOC_CGROUP] = "kmalloc-cg-" #sz,
#else
#define KMALLOC_CGROUP_NAME(sz)
#endif

#ifndef CONFIG_SLUB_TINY
#define KMALLOC_RCL_NAME(sz)    .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #sz,
#else
#define KMALLOC_RCL_NAME(sz)
#endif

#ifdef CONFIG_RANDOM_KMALLOC_CACHES
#define __KMALLOC_RANDOM_CONCAT(a, b) a ## b
#define KMALLOC_RANDOM_NAME(N, sz) __KMALLOC_RANDOM_CONCAT(KMA_RAND_, N)(sz)
#define KMA_RAND_1(sz)                  .name[KMALLOC_RANDOM_START +  1] = "kmalloc-rnd-01-" #sz,
#define KMA_RAND_2(sz)  KMA_RAND_1(sz)  .name[KMALLOC_RANDOM_START +  2] = "kmalloc-rnd-02-" #sz,
#define KMA_RAND_3(sz)  KMA_RAND_2(sz)  .name[KMALLOC_RANDOM_START +  3] = "kmalloc-rnd-03-" #sz,
#define KMA_RAND_4(sz)  KMA_RAND_3(sz)  .name[KMALLOC_RANDOM_START +  4] = "kmalloc-rnd-04-" #sz,
#define KMA_RAND_5(sz)  KMA_RAND_4(sz)  .name[KMALLOC_RANDOM_START +  5] = "kmalloc-rnd-05-" #sz,
#define KMA_RAND_6(sz)  KMA_RAND_5(sz)  .name[KMALLOC_RANDOM_START +  6] = "kmalloc-rnd-06-" #sz,
#define KMA_RAND_7(sz)  KMA_RAND_6(sz)  .name[KMALLOC_RANDOM_START +  7] = "kmalloc-rnd-07-" #sz,
#define KMA_RAND_8(sz)  KMA_RAND_7(sz)  .name[KMALLOC_RANDOM_START +  8] = "kmalloc-rnd-08-" #sz,
#define KMA_RAND_9(sz)  KMA_RAND_8(sz)  .name[KMALLOC_RANDOM_START +  9] = "kmalloc-rnd-09-" #sz,
#define KMA_RAND_10(sz) KMA_RAND_9(sz)  .name[KMALLOC_RANDOM_START + 10] = "kmalloc-rnd-10-" #sz,
#define KMA_RAND_11(sz) KMA_RAND_10(sz) .name[KMALLOC_RANDOM_START + 11] = "kmalloc-rnd-11-" #sz,
#define KMA_RAND_12(sz) KMA_RAND_11(sz) .name[KMALLOC_RANDOM_START + 12] = "kmalloc-rnd-12-" #sz,
#define KMA_RAND_13(sz) KMA_RAND_12(sz) .name[KMALLOC_RANDOM_START + 13] = "kmalloc-rnd-13-" #sz,
#define KMA_RAND_14(sz) KMA_RAND_13(sz) .name[KMALLOC_RANDOM_START + 14] = "kmalloc-rnd-14-" #sz,
#define KMA_RAND_15(sz) KMA_RAND_14(sz) .name[KMALLOC_RANDOM_START + 15] = "kmalloc-rnd-15-" #sz,
#else // CONFIG_RANDOM_KMALLOC_CACHES
#define KMALLOC_RANDOM_NAME(N, sz)
#endif

#define INIT_KMALLOC_INFO(__size, __short_size)                 \
{                                                               \
        .name[KMALLOC_NORMAL]  = "kmalloc-" #__short_size,      \
        KMALLOC_RCL_NAME(__short_size)                          \
        KMALLOC_CGROUP_NAME(__short_size)                       \
        KMALLOC_DMA_NAME(__short_size)                          \
        KMALLOC_RANDOM_NAME(RANDOM_KMALLOC_CACHES_NR, __short_size)     \
        .size = __size,                                         \
}

/*
 * kmalloc_info[] is to make slab_debug=,kmalloc-xx option work at boot time.
 * kmalloc_index() supports up to 2^21=2MB, so the final entry of the table is
 * kmalloc-2M.
 */
const struct kmalloc_info_struct kmalloc_info[] __initconst = {
        INIT_KMALLOC_INFO(0, 0),
        INIT_KMALLOC_INFO(96, 96),
        INIT_KMALLOC_INFO(192, 192),
        INIT_KMALLOC_INFO(8, 8),
        INIT_KMALLOC_INFO(16, 16),
        INIT_KMALLOC_INFO(32, 32),
        INIT_KMALLOC_INFO(64, 64),
        INIT_KMALLOC_INFO(128, 128),
        INIT_KMALLOC_INFO(256, 256),
        INIT_KMALLOC_INFO(512, 512),
        INIT_KMALLOC_INFO(1024, 1k),
        INIT_KMALLOC_INFO(2048, 2k),
        INIT_KMALLOC_INFO(4096, 4k),
        INIT_KMALLOC_INFO(8192, 8k),
        INIT_KMALLOC_INFO(16384, 16k),
        INIT_KMALLOC_INFO(32768, 32k),
        INIT_KMALLOC_INFO(65536, 64k),
        INIT_KMALLOC_INFO(131072, 128k),
        INIT_KMALLOC_INFO(262144, 256k),
        INIT_KMALLOC_INFO(524288, 512k),
        INIT_KMALLOC_INFO(1048576, 1M),
        INIT_KMALLOC_INFO(2097152, 2M)
};

/*
 * Patch up the size_index table if we have strange large alignment
 * requirements for the kmalloc array. This is only the case for
 * MIPS it seems. The standard arches will not generate any code here.
 *
 * Largest permitted alignment is 256 bytes due to the way we
 * handle the index determination for the smaller caches.
 *
 * Make sure that nothing crazy happens if someone starts tinkering
 * around with ARCH_KMALLOC_MINALIGN
 */
void __init setup_kmalloc_cache_index_table(void)
{
        unsigned int i;

        BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
                !is_power_of_2(KMALLOC_MIN_SIZE));

        for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
                unsigned int elem = size_index_elem(i);

                if (elem >= ARRAY_SIZE(kmalloc_size_index))
                        break;
                kmalloc_size_index[elem] = KMALLOC_SHIFT_LOW;
        }

        if (KMALLOC_MIN_SIZE >= 64) {
                /*
                 * The 96 byte sized cache is not used if the alignment
                 * is 64 byte.
                 */
                for (i = 64 + 8; i <= 96; i += 8)
                        kmalloc_size_index[size_index_elem(i)] = 7;

        }

        if (KMALLOC_MIN_SIZE >= 128) {
                /*
                 * The 192 byte sized cache is not used if the alignment
                 * is 128 byte. Redirect kmalloc to use the 256 byte cache
                 * instead.
                 */
                for (i = 128 + 8; i <= 192; i += 8)
                        kmalloc_size_index[size_index_elem(i)] = 8;
        }
}

static unsigned int __kmalloc_minalign(void)
{
        unsigned int minalign = dma_get_cache_alignment();

        if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) &&
            is_swiotlb_allocated())
                minalign = ARCH_KMALLOC_MINALIGN;

        return max(minalign, arch_slab_minalign());
}

static void __init
new_kmalloc_cache(int idx, enum kmalloc_cache_type type)
{
        slab_flags_t flags = 0;
        unsigned int minalign = __kmalloc_minalign();
        unsigned int aligned_size = kmalloc_info[idx].size;
        int aligned_idx = idx;

        if ((KMALLOC_RECLAIM != KMALLOC_NORMAL) && (type == KMALLOC_RECLAIM)) {
                flags |= SLAB_RECLAIM_ACCOUNT;
        } else if (IS_ENABLED(CONFIG_MEMCG) && (type == KMALLOC_CGROUP)) {
                if (mem_cgroup_kmem_disabled()) {
                        kmalloc_caches[type][idx] = kmalloc_caches[KMALLOC_NORMAL][idx];
                        return;
                }
                flags |= SLAB_ACCOUNT;
        } else if (IS_ENABLED(CONFIG_ZONE_DMA) && (type == KMALLOC_DMA)) {
                flags |= SLAB_CACHE_DMA;
        }

#ifdef CONFIG_RANDOM_KMALLOC_CACHES
        if (type >= KMALLOC_RANDOM_START && type <= KMALLOC_RANDOM_END)
                flags |= SLAB_NO_MERGE;
#endif

        /*
         * If CONFIG_MEMCG is enabled, disable cache merging for
         * KMALLOC_NORMAL caches.
         */
        if (IS_ENABLED(CONFIG_MEMCG) && (type == KMALLOC_NORMAL))
                flags |= SLAB_NO_MERGE;

        if (minalign > ARCH_KMALLOC_MINALIGN) {
                aligned_size = ALIGN(aligned_size, minalign);
                aligned_idx = __kmalloc_index(aligned_size, false);
        }

        if (!kmalloc_caches[type][aligned_idx])
                kmalloc_caches[type][aligned_idx] = create_kmalloc_cache(
                                        kmalloc_info[aligned_idx].name[type],
                                        aligned_size, flags);
        if (idx != aligned_idx)
                kmalloc_caches[type][idx] = kmalloc_caches[type][aligned_idx];
}

/*
 * Create the kmalloc array. Some of the regular kmalloc arrays
 * may already have been created because they were needed to
 * enable allocations for slab creation.
 */
void __init create_kmalloc_caches(void)
{
        int i;
        enum kmalloc_cache_type type;

        /*
         * Including KMALLOC_CGROUP if CONFIG_MEMCG defined
         */
        for (type = KMALLOC_NORMAL; type < NR_KMALLOC_TYPES; type++) {
                /* Caches that are NOT of the two-to-the-power-of size. */
                if (KMALLOC_MIN_SIZE <= 32)
                        new_kmalloc_cache(1, type);
                if (KMALLOC_MIN_SIZE <= 64)
                        new_kmalloc_cache(2, type);

                /* Caches that are of the two-to-the-power-of size. */
                for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++)
                        new_kmalloc_cache(i, type);
        }
#ifdef CONFIG_RANDOM_KMALLOC_CACHES
        random_kmalloc_seed = get_random_u64();
#endif

        /* Kmalloc array is now usable */
        slab_state = UP;

        if (IS_ENABLED(CONFIG_SLAB_BUCKETS))
                kmem_buckets_cache = kmem_cache_create("kmalloc_buckets",
                                                       sizeof(kmem_buckets),
                                                       0, SLAB_NO_MERGE, NULL);
}

/**
 * __ksize -- Report full size of underlying allocation
 * @object: pointer to the object
 *
 * This should only be used internally to query the true size of allocations.
 * It is not meant to be a way to discover the usable size of an allocation
 * after the fact. Instead, use kmalloc_size_roundup(). Using memory beyond
 * the originally requested allocation size may trigger KASAN, UBSAN_BOUNDS,
 * and/or FORTIFY_SOURCE.
 *
 * Return: size of the actual memory used by @object in bytes
 */
size_t __ksize(const void *object)
{
        struct folio *folio;

        if (unlikely(object == ZERO_SIZE_PTR))
                return 0;

        folio = virt_to_folio(object);

        if (unlikely(!folio_test_slab(folio))) {
                if (WARN_ON(folio_size(folio) <= KMALLOC_MAX_CACHE_SIZE))
                        return 0;
                if (WARN_ON(object != folio_address(folio)))
                        return 0;
                return folio_size(folio);
        }

#ifdef CONFIG_SLUB_DEBUG
        skip_orig_size_check(folio_slab(folio)->slab_cache, object);
#endif

        return slab_ksize(folio_slab(folio)->slab_cache);
}

gfp_t kmalloc_fix_flags(gfp_t flags)
{
        gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;

        flags &= ~GFP_SLAB_BUG_MASK;
        pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
                        invalid_mask, &invalid_mask, flags, &flags);
        dump_stack();

        return flags;
}

#ifdef CONFIG_SLAB_FREELIST_RANDOM
/* Randomize a generic freelist */
static void freelist_randomize(unsigned int *list,
                               unsigned int count)
{
        unsigned int rand;
        unsigned int i;

        for (i = 0; i < count; i++)
                list[i] = i;

        /* Fisher-Yates shuffle */
        for (i = count - 1; i > 0; i--) {
                rand = get_random_u32_below(i + 1);
                swap(list[i], list[rand]);
        }
}

/* Create a random sequence per cache */
int cache_random_seq_create(struct kmem_cache *cachep, unsigned int count,
                                    gfp_t gfp)
{

        if (count < 2 || cachep->random_seq)
                return 0;

        cachep->random_seq = kcalloc(count, sizeof(unsigned int), gfp);
        if (!cachep->random_seq)
                return -ENOMEM;

        freelist_randomize(cachep->random_seq, count);
        return 0;
}

/* Destroy the per-cache random freelist sequence */
void cache_random_seq_destroy(struct kmem_cache *cachep)
{
        kfree(cachep->random_seq);
        cachep->random_seq = NULL;
}
#endif /* CONFIG_SLAB_FREELIST_RANDOM */

#ifdef CONFIG_SLUB_DEBUG
#define SLABINFO_RIGHTS (0400)

static void print_slabinfo_header(struct seq_file *m)
{
        /*
         * Output format version, so at least we can change it
         * without _too_ many complaints.
         */
        seq_puts(m, "slabinfo - version: 2.1\n");
        seq_puts(m, "# name            <active_objs> <num_objs> <objsize> <objperslab> <pagesperslab>");
        seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
        seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
        seq_putc(m, '\n');
}

static void *slab_start(struct seq_file *m, loff_t *pos)
{
        mutex_lock(&slab_mutex);
        return seq_list_start(&slab_caches, *pos);
}

static void *slab_next(struct seq_file *m, void *p, loff_t *pos)
{
        return seq_list_next(p, &slab_caches, pos);
}

static void slab_stop(struct seq_file *m, void *p)
{
        mutex_unlock(&slab_mutex);
}

static void cache_show(struct kmem_cache *s, struct seq_file *m)
{
        struct slabinfo sinfo;

        memset(&sinfo, 0, sizeof(sinfo));
        get_slabinfo(s, &sinfo);

        seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
                   s->name, sinfo.active_objs, sinfo.num_objs, s->size,
                   sinfo.objects_per_slab, (1 << sinfo.cache_order));

        seq_printf(m, " : tunables %4u %4u %4u",
                   sinfo.limit, sinfo.batchcount, sinfo.shared);
        seq_printf(m, " : slabdata %6lu %6lu %6lu",
                   sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
        seq_putc(m, '\n');
}

static int slab_show(struct seq_file *m, void *p)
{
        struct kmem_cache *s = list_entry(p, struct kmem_cache, list);

        if (p == slab_caches.next)
                print_slabinfo_header(m);
        cache_show(s, m);
        return 0;
}

void dump_unreclaimable_slab(void)
{
        struct kmem_cache *s;
        struct slabinfo sinfo;

        /*
         * Here acquiring slab_mutex is risky since we don't prefer to get
         * sleep in oom path. But, without mutex hold, it may introduce a
         * risk of crash.
         * Use mutex_trylock to protect the list traverse, dump nothing
         * without acquiring the mutex.
         */
        if (!mutex_trylock(&slab_mutex)) {
                pr_warn("excessive unreclaimable slab but cannot dump stats\n");
                return;
        }

        pr_info("Unreclaimable slab info:\n");
        pr_info("Name                      Used          Total\n");

        list_for_each_entry(s, &slab_caches, list) {
                if (s->flags & SLAB_RECLAIM_ACCOUNT)
                        continue;

                get_slabinfo(s, &sinfo);

                if (sinfo.num_objs > 0)
                        pr_info("%-17s %10luKB %10luKB\n", s->name,
                                (sinfo.active_objs * s->size) / 1024,
                                (sinfo.num_objs * s->size) / 1024);
        }
        mutex_unlock(&slab_mutex);
}

/*
 * slabinfo_op - iterator that generates /proc/slabinfo
 *
 * Output layout:
 * cache-name
 * num-active-objs
 * total-objs
 * object size
 * num-active-slabs
 * total-slabs
 * num-pages-per-slab
 * + further values on SMP and with statistics enabled
 */
static const struct seq_operations slabinfo_op = {
        .start = slab_start,
        .next = slab_next,
        .stop = slab_stop,
        .show = slab_show,
};

static int slabinfo_open(struct inode *inode, struct file *file)
{
        return seq_open(file, &slabinfo_op);
}

static const struct proc_ops slabinfo_proc_ops = {
        .proc_flags     = PROC_ENTRY_PERMANENT,
        .proc_open      = slabinfo_open,
        .proc_read      = seq_read,
        .proc_lseek     = seq_lseek,
        .proc_release   = seq_release,
};

static int __init slab_proc_init(void)
{
        proc_create("slabinfo", SLABINFO_RIGHTS, NULL, &slabinfo_proc_ops);
        return 0;
}
module_init(slab_proc_init);

#endif /* CONFIG_SLUB_DEBUG */

/**
 * kfree_sensitive - Clear sensitive information in memory before freeing
 * @p: object to free memory of
 *
 * The memory of the object @p points to is zeroed before freed.
 * If @p is %NULL, kfree_sensitive() does nothing.
 *
 * Note: this function zeroes the whole allocated buffer which can be a good
 * deal bigger than the requested buffer size passed to kmalloc(). So be
 * careful when using this function in performance sensitive code.
 */
void kfree_sensitive(const void *p)
{
        size_t ks;
        void *mem = (void *)p;

        ks = ksize(mem);
        if (ks) {
                kasan_unpoison_range(mem, ks);
                memzero_explicit(mem, ks);
        }
        kfree(mem);
}
EXPORT_SYMBOL(kfree_sensitive);

size_t ksize(const void *objp)
{
        /*
         * We need to first check that the pointer to the object is valid.
         * The KASAN report printed from ksize() is more useful, then when
         * it's printed later when the behaviour could be undefined due to
         * a potential use-after-free or double-free.
         *
         * We use kasan_check_byte(), which is supported for the hardware
         * tag-based KASAN mode, unlike kasan_check_read/write().
         *
         * If the pointed to memory is invalid, we return 0 to avoid users of
         * ksize() writing to and potentially corrupting the memory region.
         *
         * We want to perform the check before __ksize(), to avoid potentially
         * crashing in __ksize() due to accessing invalid metadata.
         */
        if (unlikely(ZERO_OR_NULL_PTR(objp)) || !kasan_check_byte(objp))
                return 0;

        return kfence_ksize(objp) ?: __ksize(objp);
}
EXPORT_SYMBOL(ksize);

#ifdef CONFIG_BPF_SYSCALL
#include <linux/btf.h>

__bpf_kfunc_start_defs();

__bpf_kfunc struct kmem_cache *bpf_get_kmem_cache(u64 addr)
{
        struct slab *slab;

        if (!virt_addr_valid((void *)(long)addr))
                return NULL;

        slab = virt_to_slab((void *)(long)addr);
        return slab ? slab->slab_cache : NULL;
}

__bpf_kfunc_end_defs();
#endif /* CONFIG_BPF_SYSCALL */

/* Tracepoints definitions. */
EXPORT_TRACEPOINT_SYMBOL(kmalloc);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
EXPORT_TRACEPOINT_SYMBOL(kfree);
EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);

#ifndef CONFIG_KVFREE_RCU_BATCHED

void kvfree_call_rcu(struct rcu_head *head, void *ptr)
{
        if (head) {
                kasan_record_aux_stack(ptr);
                call_rcu(head, kvfree_rcu_cb);
                return;
        }

        // kvfree_rcu(one_arg) call.
        might_sleep();
        synchronize_rcu();
        kvfree(ptr);
}
EXPORT_SYMBOL_GPL(kvfree_call_rcu);

void __init kvfree_rcu_init(void)
{
}

#else /* CONFIG_KVFREE_RCU_BATCHED */

/*
 * This rcu parameter is runtime-read-only. It reflects
 * a minimum allowed number of objects which can be cached
 * per-CPU. Object size is equal to one page. This value
 * can be changed at boot time.
 */
static int rcu_min_cached_objs = 5;
module_param(rcu_min_cached_objs, int, 0444);

// A page shrinker can ask for pages to be freed to make them
// available for other parts of the system. This usually happens
// under low memory conditions, and in that case we should also
// defer page-cache filling for a short time period.
//
// The default value is 5 seconds, which is long enough to reduce
// interference with the shrinker while it asks other systems to
// drain their caches.
static int rcu_delay_page_cache_fill_msec = 5000;
module_param(rcu_delay_page_cache_fill_msec, int, 0444);

static struct workqueue_struct *rcu_reclaim_wq;

/* Maximum number of jiffies to wait before draining a batch. */
#define KFREE_DRAIN_JIFFIES (5 * HZ)
#define KFREE_N_BATCHES 2
#define FREE_N_CHANNELS 2

/**
 * struct kvfree_rcu_bulk_data - single block to store kvfree_rcu() pointers
 * @list: List node. All blocks are linked between each other
 * @gp_snap: Snapshot of RCU state for objects placed to this bulk
 * @nr_records: Number of active pointers in the array
 * @records: Array of the kvfree_rcu() pointers
 */
struct kvfree_rcu_bulk_data {
        struct list_head list;
        struct rcu_gp_oldstate gp_snap;
        unsigned long nr_records;
        void *records[] __counted_by(nr_records);
};

/*
 * This macro defines how many entries the "records" array
 * will contain. It is based on the fact that the size of
 * kvfree_rcu_bulk_data structure becomes exactly one page.
 */
#define KVFREE_BULK_MAX_ENTR \
        ((PAGE_SIZE - sizeof(struct kvfree_rcu_bulk_data)) / sizeof(void *))

/**
 * struct kfree_rcu_cpu_work - single batch of kfree_rcu() requests
 * @rcu_work: Let queue_rcu_work() invoke workqueue handler after grace period
 * @head_free: List of kfree_rcu() objects waiting for a grace period
 * @head_free_gp_snap: Grace-period snapshot to check for attempted premature frees.
 * @bulk_head_free: Bulk-List of kvfree_rcu() objects waiting for a grace period
 * @krcp: Pointer to @kfree_rcu_cpu structure
 */

struct kfree_rcu_cpu_work {
        struct rcu_work rcu_work;
        struct rcu_head *head_free;
        struct rcu_gp_oldstate head_free_gp_snap;
        struct list_head bulk_head_free[FREE_N_CHANNELS];
        struct kfree_rcu_cpu *krcp;
};

/**
 * struct kfree_rcu_cpu - batch up kfree_rcu() requests for RCU grace period
 * @head: List of kfree_rcu() objects not yet waiting for a grace period
 * @head_gp_snap: Snapshot of RCU state for objects placed to "@head"
 * @bulk_head: Bulk-List of kvfree_rcu() objects not yet waiting for a grace period
 * @krw_arr: Array of batches of kfree_rcu() objects waiting for a grace period
 * @lock: Synchronize access to this structure
 * @monitor_work: Promote @head to @head_free after KFREE_DRAIN_JIFFIES
 * @initialized: The @rcu_work fields have been initialized
 * @head_count: Number of objects in rcu_head singular list
 * @bulk_count: Number of objects in bulk-list
 * @bkvcache:
 *      A simple cache list that contains objects for reuse purpose.
 *      In order to save some per-cpu space the list is singular.
 *      Even though it is lockless an access has to be protected by the
 *      per-cpu lock.
 * @page_cache_work: A work to refill the cache when it is empty
 * @backoff_page_cache_fill: Delay cache refills
 * @work_in_progress: Indicates that page_cache_work is running
 * @hrtimer: A hrtimer for scheduling a page_cache_work
 * @nr_bkv_objs: number of allocated objects at @bkvcache.
 *
 * This is a per-CPU structure.  The reason that it is not included in
 * the rcu_data structure is to permit this code to be extracted from
 * the RCU files.  Such extraction could allow further optimization of
 * the interactions with the slab allocators.
 */
struct kfree_rcu_cpu {
        // Objects queued on a linked list
        // through their rcu_head structures.
        struct rcu_head *head;
        unsigned long head_gp_snap;
        atomic_t head_count;

        // Objects queued on a bulk-list.
        struct list_head bulk_head[FREE_N_CHANNELS];
        atomic_t bulk_count[FREE_N_CHANNELS];

        struct kfree_rcu_cpu_work krw_arr[KFREE_N_BATCHES];
        raw_spinlock_t lock;
        struct delayed_work monitor_work;
        bool initialized;

        struct delayed_work page_cache_work;
        atomic_t backoff_page_cache_fill;
        atomic_t work_in_progress;
        struct hrtimer hrtimer;

        struct llist_head bkvcache;
        int nr_bkv_objs;
};

static DEFINE_PER_CPU(struct kfree_rcu_cpu, krc) = {
        .lock = __RAW_SPIN_LOCK_UNLOCKED(krc.lock),
};

static __always_inline void
debug_rcu_bhead_unqueue(struct kvfree_rcu_bulk_data *bhead)
{
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
        int i;

        for (i = 0; i < bhead->nr_records; i++)
                debug_rcu_head_unqueue((struct rcu_head *)(bhead->records[i]));
#endif
}

static inline struct kfree_rcu_cpu *
krc_this_cpu_lock(unsigned long *flags)
{
        struct kfree_rcu_cpu *krcp;

        local_irq_save(*flags); // For safely calling this_cpu_ptr().
        krcp = this_cpu_ptr(&krc);
        raw_spin_lock(&krcp->lock);

        return krcp;
}

static inline void
krc_this_cpu_unlock(struct kfree_rcu_cpu *krcp, unsigned long flags)
{
        raw_spin_unlock_irqrestore(&krcp->lock, flags);
}

static inline struct kvfree_rcu_bulk_data *
get_cached_bnode(struct kfree_rcu_cpu *krcp)
{
        if (!krcp->nr_bkv_objs)
                return NULL;

        WRITE_ONCE(krcp->nr_bkv_objs, krcp->nr_bkv_objs - 1);
        return (struct kvfree_rcu_bulk_data *)
                llist_del_first(&krcp->bkvcache);
}

static inline bool
put_cached_bnode(struct kfree_rcu_cpu *krcp,
        struct kvfree_rcu_bulk_data *bnode)
{
        // Check the limit.
        if (krcp->nr_bkv_objs >= rcu_min_cached_objs)
                return false;

        llist_add((struct llist_node *) bnode, &krcp->bkvcache);
        WRITE_ONCE(krcp->nr_bkv_objs, krcp->nr_bkv_objs + 1);
        return true;
}

static int
drain_page_cache(struct kfree_rcu_cpu *krcp)
{
        unsigned long flags;
        struct llist_node *page_list, *pos, *n;
        int freed = 0;

        if (!rcu_min_cached_objs)
                return 0;

        raw_spin_lock_irqsave(&krcp->lock, flags);
        page_list = llist_del_all(&krcp->bkvcache);
        WRITE_ONCE(krcp->nr_bkv_objs, 0);
        raw_spin_unlock_irqrestore(&krcp->lock, flags);

        llist_for_each_safe(pos, n, page_list) {
                free_page((unsigned long)pos);
                freed++;
        }

        return freed;
}

static void
kvfree_rcu_bulk(struct kfree_rcu_cpu *krcp,
        struct kvfree_rcu_bulk_data *bnode, int idx)
{
        unsigned long flags;
        int i;

        if (!WARN_ON_ONCE(!poll_state_synchronize_rcu_full(&bnode->gp_snap))) {
                debug_rcu_bhead_unqueue(bnode);
                rcu_lock_acquire(&rcu_callback_map);
                if (idx == 0) { // kmalloc() / kfree().
                        trace_rcu_invoke_kfree_bulk_callback(
                                "slab", bnode->nr_records,
                                bnode->records);

                        kfree_bulk(bnode->nr_records, bnode->records);
                } else { // vmalloc() / vfree().
                        for (i = 0; i < bnode->nr_records; i++) {
                                trace_rcu_invoke_kvfree_callback(
                                        "slab", bnode->records[i], 0);

                                vfree(bnode->records[i]);
                        }
                }
                rcu_lock_release(&rcu_callback_map);
        }

        raw_spin_lock_irqsave(&krcp->lock, flags);
        if (put_cached_bnode(krcp, bnode))
                bnode = NULL;
        raw_spin_unlock_irqrestore(&krcp->lock, flags);

        if (bnode)
                free_page((unsigned long) bnode);

        cond_resched_tasks_rcu_qs();
}

static void
kvfree_rcu_list(struct rcu_head *head)
{
        struct rcu_head *next;

        for (; head; head = next) {
                void *ptr = (void *) head->func;
                unsigned long offset = (void *) head - ptr;

                next = head->next;
                debug_rcu_head_unqueue((struct rcu_head *)ptr);
                rcu_lock_acquire(&rcu_callback_map);
                trace_rcu_invoke_kvfree_callback("slab", head, offset);

                kvfree(ptr);

                rcu_lock_release(&rcu_callback_map);
                cond_resched_tasks_rcu_qs();
        }
}

/*
 * This function is invoked in workqueue context after a grace period.
 * It frees all the objects queued on ->bulk_head_free or ->head_free.
 */
static void kfree_rcu_work(struct work_struct *work)
{
        unsigned long flags;
        struct kvfree_rcu_bulk_data *bnode, *n;
        struct list_head bulk_head[FREE_N_CHANNELS];
        struct rcu_head *head;
        struct kfree_rcu_cpu *krcp;
        struct kfree_rcu_cpu_work *krwp;
        struct rcu_gp_oldstate head_gp_snap;
        int i;

        krwp = container_of(to_rcu_work(work),
                struct kfree_rcu_cpu_work, rcu_work);
        krcp = krwp->krcp;

        raw_spin_lock_irqsave(&krcp->lock, flags);
        // Channels 1 and 2.
        for (i = 0; i < FREE_N_CHANNELS; i++)
                list_replace_init(&krwp->bulk_head_free[i], &bulk_head[i]);

        // Channel 3.
        head = krwp->head_free;
        krwp->head_free = NULL;
        head_gp_snap = krwp->head_free_gp_snap;
        raw_spin_unlock_irqrestore(&krcp->lock, flags);

        // Handle the first two channels.
        for (i = 0; i < FREE_N_CHANNELS; i++) {
                // Start from the tail page, so a GP is likely passed for it.
                list_for_each_entry_safe(bnode, n, &bulk_head[i], list)
                        kvfree_rcu_bulk(krcp, bnode, i);
        }

        /*
         * This is used when the "bulk" path can not be used for the
         * double-argument of kvfree_rcu().  This happens when the
         * page-cache is empty, which means that objects are instead
         * queued on a linked list through their rcu_head structures.
         * This list is named "Channel 3".
         */
        if (head && !WARN_ON_ONCE(!poll_state_synchronize_rcu_full(&head_gp_snap)))
                kvfree_rcu_list(head);
}

static bool
need_offload_krc(struct kfree_rcu_cpu *krcp)
{
        int i;

        for (i = 0; i < FREE_N_CHANNELS; i++)
                if (!list_empty(&krcp->bulk_head[i]))
                        return true;

        return !!READ_ONCE(krcp->head);
}

static bool
need_wait_for_krwp_work(struct kfree_rcu_cpu_work *krwp)
{
        int i;

        for (i = 0; i < FREE_N_CHANNELS; i++)
                if (!list_empty(&krwp->bulk_head_free[i]))
                        return true;

        return !!krwp->head_free;
}

static int krc_count(struct kfree_rcu_cpu *krcp)
{
        int sum = atomic_read(&krcp->head_count);
        int i;

        for (i = 0; i < FREE_N_CHANNELS; i++)
                sum += atomic_read(&krcp->bulk_count[i]);

        return sum;
}

static void
__schedule_delayed_monitor_work(struct kfree_rcu_cpu *krcp)
{
        long delay, delay_left;

        delay = krc_count(krcp) >= KVFREE_BULK_MAX_ENTR ? 1:KFREE_DRAIN_JIFFIES;
        if (delayed_work_pending(&krcp->monitor_work)) {
                delay_left = krcp->monitor_work.timer.expires - jiffies;
                if (delay < delay_left)
                        mod_delayed_work(rcu_reclaim_wq, &krcp->monitor_work, delay);
                return;
        }
        queue_delayed_work(rcu_reclaim_wq, &krcp->monitor_work, delay);
}

static void
schedule_delayed_monitor_work(struct kfree_rcu_cpu *krcp)
{
        unsigned long flags;

        raw_spin_lock_irqsave(&krcp->lock, flags);
        __schedule_delayed_monitor_work(krcp);
        raw_spin_unlock_irqrestore(&krcp->lock, flags);
}

static void
kvfree_rcu_drain_ready(struct kfree_rcu_cpu *krcp)
{
        struct list_head bulk_ready[FREE_N_CHANNELS];
        struct kvfree_rcu_bulk_data *bnode, *n;
        struct rcu_head *head_ready = NULL;
        unsigned long flags;
        int i;

        raw_spin_lock_irqsave(&krcp->lock, flags);
        for (i = 0; i < FREE_N_CHANNELS; i++) {
                INIT_LIST_HEAD(&bulk_ready[i]);

                list_for_each_entry_safe_reverse(bnode, n, &krcp->bulk_head[i], list) {
                        if (!poll_state_synchronize_rcu_full(&bnode->gp_snap))
                                break;

                        atomic_sub(bnode->nr_records, &krcp->bulk_count[i]);
                        list_move(&bnode->list, &bulk_ready[i]);
                }
        }

        if (krcp->head && poll_state_synchronize_rcu(krcp->head_gp_snap)) {
                head_ready = krcp->head;
                atomic_set(&krcp->head_count, 0);
                WRITE_ONCE(krcp->head, NULL);
        }
        raw_spin_unlock_irqrestore(&krcp->lock, flags);

        for (i = 0; i < FREE_N_CHANNELS; i++) {
                list_for_each_entry_safe(bnode, n, &bulk_ready[i], list)
                        kvfree_rcu_bulk(krcp, bnode, i);
        }

        if (head_ready)
                kvfree_rcu_list(head_ready);
}

/*
 * Return: %true if a work is queued, %false otherwise.
 */
static bool
kvfree_rcu_queue_batch(struct kfree_rcu_cpu *krcp)
{
        unsigned long flags;
        bool queued = false;
        int i, j;

        raw_spin_lock_irqsave(&krcp->lock, flags);

        // Attempt to start a new batch.
        for (i = 0; i < KFREE_N_BATCHES; i++) {
                struct kfree_rcu_cpu_work *krwp = &(krcp->krw_arr[i]);

                // Try to detach bulk_head or head and attach it, only when
                // all channels are free.  Any channel is not free means at krwp
                // there is on-going rcu work to handle krwp's free business.
                if (need_wait_for_krwp_work(krwp))
                        continue;

                // kvfree_rcu_drain_ready() might handle this krcp, if so give up.
                if (need_offload_krc(krcp)) {
                        // Channel 1 corresponds to the SLAB-pointer bulk path.
                        // Channel 2 corresponds to vmalloc-pointer bulk path.
                        for (j = 0; j < FREE_N_CHANNELS; j++) {
                                if (list_empty(&krwp->bulk_head_free[j])) {
                                        atomic_set(&krcp->bulk_count[j], 0);
                                        list_replace_init(&krcp->bulk_head[j],
                                                &krwp->bulk_head_free[j]);
                                }
                        }

                        // Channel 3 corresponds to both SLAB and vmalloc
                        // objects queued on the linked list.
                        if (!krwp->head_free) {
                                krwp->head_free = krcp->head;
                                get_state_synchronize_rcu_full(&krwp->head_free_gp_snap);
                                atomic_set(&krcp->head_count, 0);
                                WRITE_ONCE(krcp->head, NULL);
                        }

                        // One work is per one batch, so there are three
                        // "free channels", the batch can handle. Break
                        // the loop since it is done with this CPU thus
                        // queuing an RCU work is _always_ success here.
                        queued = queue_rcu_work(rcu_reclaim_wq, &krwp->rcu_work);
                        WARN_ON_ONCE(!queued);
                        break;
                }
        }

        raw_spin_unlock_irqrestore(&krcp->lock, flags);
        return queued;
}

/*
 * This function is invoked after the KFREE_DRAIN_JIFFIES timeout.
 */
static void kfree_rcu_monitor(struct work_struct *work)
{
        struct kfree_rcu_cpu *krcp = container_of(work,
                struct kfree_rcu_cpu, monitor_work.work);

        // Drain ready for reclaim.
        kvfree_rcu_drain_ready(krcp);

        // Queue a batch for a rest.
        kvfree_rcu_queue_batch(krcp);

        // If there is nothing to detach, it means that our job is
        // successfully done here. In case of having at least one
        // of the channels that is still busy we should rearm the
        // work to repeat an attempt. Because previous batches are
        // still in progress.
        if (need_offload_krc(krcp))
                schedule_delayed_monitor_work(krcp);
}

static void fill_page_cache_func(struct work_struct *work)
{
        struct kvfree_rcu_bulk_data *bnode;
        struct kfree_rcu_cpu *krcp =
                container_of(work, struct kfree_rcu_cpu,
                        page_cache_work.work);
        unsigned long flags;
        int nr_pages;
        bool pushed;
        int i;

        nr_pages = atomic_read(&krcp->backoff_page_cache_fill) ?
                1 : rcu_min_cached_objs;

        for (i = READ_ONCE(krcp->nr_bkv_objs); i < nr_pages; i++) {
                bnode = (struct kvfree_rcu_bulk_data *)
                        __get_free_page(GFP_KERNEL | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);

                if (!bnode)
                        break;

                raw_spin_lock_irqsave(&krcp->lock, flags);
                pushed = put_cached_bnode(krcp, bnode);
                raw_spin_unlock_irqrestore(&krcp->lock, flags);

                if (!pushed) {
                        free_page((unsigned long) bnode);
                        break;
                }
        }

        atomic_set(&krcp->work_in_progress, 0);
        atomic_set(&krcp->backoff_page_cache_fill, 0);
}

// Record ptr in a page managed by krcp, with the pre-krc_this_cpu_lock()
// state specified by flags.  If can_alloc is true, the caller must
// be schedulable and not be holding any locks or mutexes that might be
// acquired by the memory allocator or anything that it might invoke.
// Returns true if ptr was successfully recorded, else the caller must
// use a fallback.
static inline bool
add_ptr_to_bulk_krc_lock(struct kfree_rcu_cpu **krcp,
        unsigned long *flags, void *ptr, bool can_alloc)
{
        struct kvfree_rcu_bulk_data *bnode;
        int idx;

        *krcp = krc_this_cpu_lock(flags);
        if (unlikely(!(*krcp)->initialized))
                return false;

        idx = !!is_vmalloc_addr(ptr);
        bnode = list_first_entry_or_null(&(*krcp)->bulk_head[idx],
                struct kvfree_rcu_bulk_data, list);

        /* Check if a new block is required. */
        if (!bnode || bnode->nr_records == KVFREE_BULK_MAX_ENTR) {
                bnode = get_cached_bnode(*krcp);
                if (!bnode && can_alloc) {
                        krc_this_cpu_unlock(*krcp, *flags);

                        // __GFP_NORETRY - allows a light-weight direct reclaim
                        // what is OK from minimizing of fallback hitting point of
                        // view. Apart of that it forbids any OOM invoking what is
                        // also beneficial since we are about to release memory soon.
                        //
                        // __GFP_NOMEMALLOC - prevents from consuming of all the
                        // memory reserves. Please note we have a fallback path.
                        //
                        // __GFP_NOWARN - it is supposed that an allocation can
                        // be failed under low memory or high memory pressure
                        // scenarios.
                        bnode = (struct kvfree_rcu_bulk_data *)
                                __get_free_page(GFP_KERNEL | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN);
                        raw_spin_lock_irqsave(&(*krcp)->lock, *flags);
                }

                if (!bnode)
                        return false;

                // Initialize the new block and attach it.
                bnode->nr_records = 0;
                list_add(&bnode->list, &(*krcp)->bulk_head[idx]);
        }

        // Finally insert and update the GP for this page.
        bnode->nr_records++;
        bnode->records[bnode->nr_records - 1] = ptr;
        get_state_synchronize_rcu_full(&bnode->gp_snap);
        atomic_inc(&(*krcp)->bulk_count[idx]);

        return true;
}

static enum hrtimer_restart
schedule_page_work_fn(struct hrtimer *t)
{
        struct kfree_rcu_cpu *krcp =
                container_of(t, struct kfree_rcu_cpu, hrtimer);

        queue_delayed_work(system_highpri_wq, &krcp->page_cache_work, 0);
        return HRTIMER_NORESTART;
}

static void
run_page_cache_worker(struct kfree_rcu_cpu *krcp)
{
        // If cache disabled, bail out.
        if (!rcu_min_cached_objs)
                return;

        if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING &&
                        !atomic_xchg(&krcp->work_in_progress, 1)) {
                if (atomic_read(&krcp->backoff_page_cache_fill)) {
                        queue_delayed_work(rcu_reclaim_wq,
                                &krcp->page_cache_work,
                                        msecs_to_jiffies(rcu_delay_page_cache_fill_msec));
                } else {
                        hrtimer_setup(&krcp->hrtimer, schedule_page_work_fn, CLOCK_MONOTONIC,
                                      HRTIMER_MODE_REL);
                        hrtimer_start(&krcp->hrtimer, 0, HRTIMER_MODE_REL);
                }
        }
}

void __init kfree_rcu_scheduler_running(void)
{
        int cpu;

        for_each_possible_cpu(cpu) {
                struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);

                if (need_offload_krc(krcp))
                        schedule_delayed_monitor_work(krcp);
        }
}

/*
 * Queue a request for lazy invocation of the appropriate free routine
 * after a grace period.  Please note that three paths are maintained,
 * two for the common case using arrays of pointers and a third one that
 * is used only when the main paths cannot be used, for example, due to
 * memory pressure.
 *
 * Each kvfree_call_rcu() request is added to a batch. The batch will be drained
 * every KFREE_DRAIN_JIFFIES number of jiffies. All the objects in the batch will
 * be free'd in workqueue context. This allows us to: batch requests together to
 * reduce the number of grace periods during heavy kfree_rcu()/kvfree_rcu() load.
 */
void kvfree_call_rcu(struct rcu_head *head, void *ptr)
{
        unsigned long flags;
        struct kfree_rcu_cpu *krcp;
        bool success;

        /*
         * Please note there is a limitation for the head-less
         * variant, that is why there is a clear rule for such
         * objects: it can be used from might_sleep() context
         * only. For other places please embed an rcu_head to
         * your data.
         */
        if (!head)
                might_sleep();

        // Queue the object but don't yet schedule the batch.
        if (debug_rcu_head_queue(ptr)) {
                // Probable double kfree_rcu(), just leak.
                WARN_ONCE(1, "%s(): Double-freed call. rcu_head %p\n",
                          __func__, head);

                // Mark as success and leave.
                return;
        }

        kasan_record_aux_stack(ptr);
        success = add_ptr_to_bulk_krc_lock(&krcp, &flags, ptr, !head);
        if (!success) {
                run_page_cache_worker(krcp);

                if (head == NULL)
                        // Inline if kvfree_rcu(one_arg) call.
                        goto unlock_return;

                head->func = ptr;
                head->next = krcp->head;
                WRITE_ONCE(krcp->head, head);
                atomic_inc(&krcp->head_count);

                // Take a snapshot for this krcp.
                krcp->head_gp_snap = get_state_synchronize_rcu();
                success = true;
        }

        /*
         * The kvfree_rcu() caller considers the pointer freed at this point
         * and likely removes any references to it. Since the actual slab
         * freeing (and kmemleak_free()) is deferred, tell kmemleak to ignore
         * this object (no scanning or false positives reporting).
         */
        kmemleak_ignore(ptr);

        // Set timer to drain after KFREE_DRAIN_JIFFIES.
        if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING)
                __schedule_delayed_monitor_work(krcp);

unlock_return:
        krc_this_cpu_unlock(krcp, flags);

        /*
         * Inline kvfree() after synchronize_rcu(). We can do
         * it from might_sleep() context only, so the current
         * CPU can pass the QS state.
         */
        if (!success) {
                debug_rcu_head_unqueue((struct rcu_head *) ptr);
                synchronize_rcu();
                kvfree(ptr);
        }
}
EXPORT_SYMBOL_GPL(kvfree_call_rcu);

/**
 * kvfree_rcu_barrier - Wait until all in-flight kvfree_rcu() complete.
 *
 * Note that a single argument of kvfree_rcu() call has a slow path that
 * triggers synchronize_rcu() following by freeing a pointer. It is done
 * before the return from the function. Therefore for any single-argument
 * call that will result in a kfree() to a cache that is to be destroyed
 * during module exit, it is developer's responsibility to ensure that all
 * such calls have returned before the call to kmem_cache_destroy().
 */
void kvfree_rcu_barrier(void)
{
        struct kfree_rcu_cpu_work *krwp;
        struct kfree_rcu_cpu *krcp;
        bool queued;
        int i, cpu;

        /*
         * Firstly we detach objects and queue them over an RCU-batch
         * for all CPUs. Finally queued works are flushed for each CPU.
         *
         * Please note. If there are outstanding batches for a particular
         * CPU, those have to be finished first following by queuing a new.
         */
        for_each_possible_cpu(cpu) {
                krcp = per_cpu_ptr(&krc, cpu);

                /*
                 * Check if this CPU has any objects which have been queued for a
                 * new GP completion. If not(means nothing to detach), we are done
                 * with it. If any batch is pending/running for this "krcp", below
                 * per-cpu flush_rcu_work() waits its completion(see last step).
                 */
                if (!need_offload_krc(krcp))
                        continue;

                while (1) {
                        /*
                         * If we are not able to queue a new RCU work it means:
                         * - batches for this CPU are still in flight which should
                         *   be flushed first and then repeat;
                         * - no objects to detach, because of concurrency.
                         */
                        queued = kvfree_rcu_queue_batch(krcp);

                        /*
                         * Bail out, if there is no need to offload this "krcp"
                         * anymore. As noted earlier it can run concurrently.
                         */
                        if (queued || !need_offload_krc(krcp))
                                break;

                        /* There are ongoing batches. */
                        for (i = 0; i < KFREE_N_BATCHES; i++) {
                                krwp = &(krcp->krw_arr[i]);
                                flush_rcu_work(&krwp->rcu_work);
                        }
                }
        }

        /*
         * Now we guarantee that all objects are flushed.
         */
        for_each_possible_cpu(cpu) {
                krcp = per_cpu_ptr(&krc, cpu);

                /*
                 * A monitor work can drain ready to reclaim objects
                 * directly. Wait its completion if running or pending.
                 */
                cancel_delayed_work_sync(&krcp->monitor_work);

                for (i = 0; i < KFREE_N_BATCHES; i++) {
                        krwp = &(krcp->krw_arr[i]);
                        flush_rcu_work(&krwp->rcu_work);
                }
        }
}
EXPORT_SYMBOL_GPL(kvfree_rcu_barrier);

static unsigned long
kfree_rcu_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
{
        int cpu;
        unsigned long count = 0;

        /* Snapshot count of all CPUs */
        for_each_possible_cpu(cpu) {
                struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);

                count += krc_count(krcp);
                count += READ_ONCE(krcp->nr_bkv_objs);
                atomic_set(&krcp->backoff_page_cache_fill, 1);
        }

        return count == 0 ? SHRINK_EMPTY : count;
}

static unsigned long
kfree_rcu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
{
        int cpu, freed = 0;

        for_each_possible_cpu(cpu) {
                int count;
                struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);

                count = krc_count(krcp);
                count += drain_page_cache(krcp);
                kfree_rcu_monitor(&krcp->monitor_work.work);

                sc->nr_to_scan -= count;
                freed += count;

                if (sc->nr_to_scan <= 0)
                        break;
        }

        return freed == 0 ? SHRINK_STOP : freed;
}

void __init kvfree_rcu_init(void)
{
        int cpu;
        int i, j;
        struct shrinker *kfree_rcu_shrinker;

        rcu_reclaim_wq = alloc_workqueue("kvfree_rcu_reclaim",
                        WQ_UNBOUND | WQ_MEM_RECLAIM, 0);
        WARN_ON(!rcu_reclaim_wq);

        /* Clamp it to [0:100] seconds interval. */
        if (rcu_delay_page_cache_fill_msec < 0 ||
                rcu_delay_page_cache_fill_msec > 100 * MSEC_PER_SEC) {

                rcu_delay_page_cache_fill_msec =
                        clamp(rcu_delay_page_cache_fill_msec, 0,
                                (int) (100 * MSEC_PER_SEC));

                pr_info("Adjusting rcutree.rcu_delay_page_cache_fill_msec to %d ms.\n",
                        rcu_delay_page_cache_fill_msec);
        }

        for_each_possible_cpu(cpu) {
                struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu);

                for (i = 0; i < KFREE_N_BATCHES; i++) {
                        INIT_RCU_WORK(&krcp->krw_arr[i].rcu_work, kfree_rcu_work);
                        krcp->krw_arr[i].krcp = krcp;

                        for (j = 0; j < FREE_N_CHANNELS; j++)
                                INIT_LIST_HEAD(&krcp->krw_arr[i].bulk_head_free[j]);
                }

                for (i = 0; i < FREE_N_CHANNELS; i++)
                        INIT_LIST_HEAD(&krcp->bulk_head[i]);

                INIT_DELAYED_WORK(&krcp->monitor_work, kfree_rcu_monitor);
                INIT_DELAYED_WORK(&krcp->page_cache_work, fill_page_cache_func);
                krcp->initialized = true;
        }

        kfree_rcu_shrinker = shrinker_alloc(0, "slab-kvfree-rcu");
        if (!kfree_rcu_shrinker) {
                pr_err("Failed to allocate kfree_rcu() shrinker!\n");
                return;
        }

        kfree_rcu_shrinker->count_objects = kfree_rcu_shrink_count;
        kfree_rcu_shrinker->scan_objects = kfree_rcu_shrink_scan;

        shrinker_register(kfree_rcu_shrinker);
}

#endif /* CONFIG_KVFREE_RCU_BATCHED */