Initial import

1 files changed, 1171 insertions, 0 deletions

diff --git a/mm/slab_common.c b/mm/slab_common.c
new file mode 100644
index 000000000..999bb3424
--- /dev/null
+++ b/mm/slab_common.c
@@ -0,0 +1,1171 @@
+/*
+ * Slab allocator functions that are independent of the allocator strategy
+ *
+ * (C) 2012 Christoph Lameter <cl@linux.com>
+ */
+#include <linux/slab.h>
+
+#include <linux/mm.h>
+#include <linux/poison.h>
+#include <linux/interrupt.h>
+#include <linux/memory.h>
+#include <linux/compiler.h>
+#include <linux/module.h>
+#include <linux/cpu.h>
+#include <linux/uaccess.h>
+#include <linux/seq_file.h>
+#include <linux/proc_fs.h>
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+#include <asm/page.h>
+#include <linux/memcontrol.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/kmem.h>
+
+#include "slab.h"
+
+enum slab_state slab_state;
+LIST_HEAD(slab_caches);
+DEFINE_MUTEX(slab_mutex);
+struct kmem_cache *kmem_cache;
+
+/*
+ * Set of flags that will prevent slab merging
+ */
+#define SLAB_NEVER_MERGE (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER | \
+		SLAB_TRACE | SLAB_DESTROY_BY_RCU | SLAB_NOLEAKTRACE | \
+		SLAB_FAILSLAB)
+
+#define SLAB_MERGE_SAME (SLAB_DEBUG_FREE | SLAB_RECLAIM_ACCOUNT | \
+		SLAB_CACHE_DMA | SLAB_NOTRACK)
+
+/*
+ * Merge control. If this is set then no merging of slab caches will occur.
+ * (Could be removed. This was introduced to pacify the merge skeptics.)
+ */
+static int slab_nomerge;
+
+static int __init setup_slab_nomerge(char *str)
+{
+	slab_nomerge = 1;
+	return 1;
+}
+
+#ifdef CONFIG_SLUB
+__setup_param("slub_nomerge", slub_nomerge, setup_slab_nomerge, 0);
+#endif
+
+__setup("slab_nomerge", setup_slab_nomerge);
+
+/*
+ * Determine the size of a slab object
+ */
+unsigned int kmem_cache_size(struct kmem_cache *s)
+{
+	return s->object_size;
+}
+EXPORT_SYMBOL(kmem_cache_size);
+
+#ifdef CONFIG_DEBUG_VM
+static int kmem_cache_sanity_check(const char *name, size_t size)
+{
+	struct kmem_cache *s = NULL;
+
+	if (!name || in_interrupt() || size < sizeof(void *) ||
+		size > KMALLOC_MAX_SIZE) {
+		pr_err("kmem_cache_create(%s) integrity check failed\n", name);
+		return -EINVAL;
+	}
+
+	list_for_each_entry(s, &slab_caches, list) {
+		char tmp;
+		int res;
+
+		/*
+		 * This happens when the module gets unloaded and doesn't
+		 * destroy its slab cache and no-one else reuses the vmalloc
+		 * area of the module.  Print a warning.
+		 */
+		res = probe_kernel_address(s->name, tmp);
+		if (res) {
+			pr_err("Slab cache with size %d has lost its name\n",
+			       s->object_size);
+			continue;
+		}
+	}
+
+	WARN_ON(strchr(name, ' '));	/* It confuses parsers */
+	return 0;
+}
+#else
+static inline int kmem_cache_sanity_check(const char *name, size_t size)
+{
+	return 0;
+}
+#endif
+
+#ifdef CONFIG_MEMCG_KMEM
+void slab_init_memcg_params(struct kmem_cache *s)
+{
+	s->memcg_params.is_root_cache = true;
+	INIT_LIST_HEAD(&s->memcg_params.list);
+	RCU_INIT_POINTER(s->memcg_params.memcg_caches, NULL);
+}
+
+static int init_memcg_params(struct kmem_cache *s,
+		struct mem_cgroup *memcg, struct kmem_cache *root_cache)
+{
+	struct memcg_cache_array *arr;
+
+	if (memcg) {
+		s->memcg_params.is_root_cache = false;
+		s->memcg_params.memcg = memcg;
+		s->memcg_params.root_cache = root_cache;
+		return 0;
+	}
+
+	slab_init_memcg_params(s);
+
+	if (!memcg_nr_cache_ids)
+		return 0;
+
+	arr = kzalloc(sizeof(struct memcg_cache_array) +
+		      memcg_nr_cache_ids * sizeof(void *),
+		      GFP_KERNEL);
+	if (!arr)
+		return -ENOMEM;
+
+	RCU_INIT_POINTER(s->memcg_params.memcg_caches, arr);
+	return 0;
+}
+
+static void destroy_memcg_params(struct kmem_cache *s)
+{
+	if (is_root_cache(s))
+		kfree(rcu_access_pointer(s->memcg_params.memcg_caches));
+}
+
+static int update_memcg_params(struct kmem_cache *s, int new_array_size)
+{
+	struct memcg_cache_array *old, *new;
+
+	if (!is_root_cache(s))
+		return 0;
+
+	new = kzalloc(sizeof(struct memcg_cache_array) +
+		      new_array_size * sizeof(void *), GFP_KERNEL);
+	if (!new)
+		return -ENOMEM;
+
+	old = rcu_dereference_protected(s->memcg_params.memcg_caches,
+					lockdep_is_held(&slab_mutex));
+	if (old)
+		memcpy(new->entries, old->entries,
+		       memcg_nr_cache_ids * sizeof(void *));
+
+	rcu_assign_pointer(s->memcg_params.memcg_caches, new);
+	if (old)
+		kfree_rcu(old, rcu);
+	return 0;
+}
+
+int memcg_update_all_caches(int num_memcgs)
+{
+	struct kmem_cache *s;
+	int ret = 0;
+
+	mutex_lock(&slab_mutex);
+	list_for_each_entry(s, &slab_caches, list) {
+		ret = update_memcg_params(s, num_memcgs);
+		/*
+		 * Instead of freeing the memory, we'll just leave the caches
+		 * up to this point in an updated state.
+		 */
+		if (ret)
+			break;
+	}
+	mutex_unlock(&slab_mutex);
+	return ret;
+}
+#else
+static inline int init_memcg_params(struct kmem_cache *s,
+		struct mem_cgroup *memcg, struct kmem_cache *root_cache)
+{
+	return 0;
+}
+
+static inline void destroy_memcg_params(struct kmem_cache *s)
+{
+}
+#endif /* CONFIG_MEMCG_KMEM */
+
+/*
+ * Find a mergeable slab cache
+ */
+int slab_unmergeable(struct kmem_cache *s)
+{
+	if (slab_nomerge || (s->flags & SLAB_NEVER_MERGE))
+		return 1;
+
+	if (!is_root_cache(s))
+		return 1;
+
+	if (s->ctor)
+		return 1;
+
+	/*
+	 * We may have set a slab to be unmergeable during bootstrap.
+	 */
+	if (s->refcount < 0)
+		return 1;
+
+	return 0;
+}
+
+struct kmem_cache *find_mergeable(size_t size, size_t align,
+		unsigned long flags, const char *name, void (*ctor)(void *))
+{
+	struct kmem_cache *s;
+
+	if (slab_nomerge || (flags & SLAB_NEVER_MERGE))
+		return NULL;
+
+	if (ctor)
+		return NULL;
+
+	size = ALIGN(size, sizeof(void *));
+	align = calculate_alignment(flags, align, size);
+	size = ALIGN(size, align);
+	flags = kmem_cache_flags(size, flags, name, NULL);
+
+	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;
+
+		if (IS_ENABLED(CONFIG_SLAB) && align &&
+			(align > s->align || s->align % align))
+			continue;
+
+		return s;
+	}
+	return NULL;
+}
+
+/*
+ * Figure out what the alignment of the objects will be given a set of
+ * flags, a user specified alignment and the size of the objects.
+ */
+unsigned long calculate_alignment(unsigned long flags,
+		unsigned long align, unsigned long size)
+{
+	/*
+	 * If the user wants hardware cache aligned objects then follow that
+	 * suggestion if the object is sufficiently large.
+	 *
+	 * The hardware cache alignment cannot override the specified
+	 * alignment though. If that is greater then use it.
+	 */
+	if (flags & SLAB_HWCACHE_ALIGN) {
+		unsigned long ralign = cache_line_size();
+		while (size <= ralign / 2)
+			ralign /= 2;
+		align = max(align, ralign);
+	}
+
+	if (align < ARCH_SLAB_MINALIGN)
+		align = ARCH_SLAB_MINALIGN;
+
+	return ALIGN(align, sizeof(void *));
+}
+
+static struct kmem_cache *
+do_kmem_cache_create(const char *name, size_t object_size, size_t size,
+		     size_t align, unsigned long flags, void (*ctor)(void *),
+		     struct mem_cgroup *memcg, struct kmem_cache *root_cache)
+{
+	struct kmem_cache *s;
+	int err;
+
+	err = -ENOMEM;
+	s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
+	if (!s)
+		goto out;
+
+	s->name = name;
+	s->object_size = object_size;
+	s->size = size;
+	s->align = align;
+	s->ctor = ctor;
+
+	err = init_memcg_params(s, memcg, root_cache);
+	if (err)
+		goto out_free_cache;
+
+	err = __kmem_cache_create(s, flags);
+	if (err)
+		goto out_free_cache;
+
+	s->refcount = 1;
+	list_add(&s->list, &slab_caches);
+out:
+	if (err)
+		return ERR_PTR(err);
+	return s;
+
+out_free_cache:
+	destroy_memcg_params(s);
+	kmem_cache_free(kmem_cache, s);
+	goto out;
+}
+
+/*
+ * kmem_cache_create - Create a cache.
+ * @name: A string which is used in /proc/slabinfo to identify this cache.
+ * @size: The size of objects to be created in this cache.
+ * @align: The required alignment for the objects.
+ * @flags: SLAB flags
+ * @ctor: A constructor for the objects.
+ *
+ * Returns a ptr to the cache on success, NULL on failure.
+ * Cannot be called within a interrupt, but can be interrupted.
+ * The @ctor is run when new pages are allocated by the cache.
+ *
+ * The flags are
+ *
+ * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
+ * to catch references to uninitialised memory.
+ *
+ * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
+ * for buffer overruns.
+ *
+ * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
+ * cacheline.  This can be beneficial if you're counting cycles as closely
+ * as davem.
+ */
+struct kmem_cache *
+kmem_cache_create(const char *name, size_t size, size_t align,
+		  unsigned long flags, void (*ctor)(void *))
+{
+	struct kmem_cache *s;
+	const char *cache_name;
+	int err;
+
+	get_online_cpus();
+	get_online_mems();
+	memcg_get_cache_ids();
+
+	mutex_lock(&slab_mutex);
+
+	err = kmem_cache_sanity_check(name, size);
+	if (err) {
+		s = NULL;	/* suppress uninit var warning */
+		goto out_unlock;
+	}
+
+	/*
+	 * Some allocators will constraint the set of valid flags to a subset
+	 * of all flags. We expect them to define CACHE_CREATE_MASK in this
+	 * case, and we'll just provide them with a sanitized version of the
+	 * passed flags.
+	 */
+	flags &= CACHE_CREATE_MASK;
+
+	s = __kmem_cache_alias(name, size, align, flags, ctor);
+	if (s)
+		goto out_unlock;
+
+	cache_name = kstrdup_const(name, GFP_KERNEL);
+	if (!cache_name) {
+		err = -ENOMEM;
+		goto out_unlock;
+	}
+
+	s = do_kmem_cache_create(cache_name, size, size,
+				 calculate_alignment(flags, align, size),
+				 flags, ctor, NULL, NULL);
+	if (IS_ERR(s)) {
+		err = PTR_ERR(s);
+		kfree_const(cache_name);
+	}
+
+out_unlock:
+	mutex_unlock(&slab_mutex);
+
+	memcg_put_cache_ids();
+	put_online_mems();
+	put_online_cpus();
+
+	if (err) {
+		if (flags & SLAB_PANIC)
+			panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
+				name, err);
+		else {
+			printk(KERN_WARNING "kmem_cache_create(%s) failed with error %d",
+				name, err);
+			dump_stack();
+		}
+		return NULL;
+	}
+	return s;
+}
+EXPORT_SYMBOL(kmem_cache_create);
+
+static int do_kmem_cache_shutdown(struct kmem_cache *s,
+		struct list_head *release, bool *need_rcu_barrier)
+{
+	if (__kmem_cache_shutdown(s) != 0) {
+		printk(KERN_ERR "kmem_cache_destroy %s: "
+		       "Slab cache still has objects\n", s->name);
+		dump_stack();
+		return -EBUSY;
+	}
+
+	if (s->flags & SLAB_DESTROY_BY_RCU)
+		*need_rcu_barrier = true;
+
+#ifdef CONFIG_MEMCG_KMEM
+	if (!is_root_cache(s))
+		list_del(&s->memcg_params.list);
+#endif
+	list_move(&s->list, release);
+	return 0;
+}
+
+static void do_kmem_cache_release(struct list_head *release,
+				  bool need_rcu_barrier)
+{
+	struct kmem_cache *s, *s2;
+
+	if (need_rcu_barrier)
+		rcu_barrier();
+
+	list_for_each_entry_safe(s, s2, release, list) {
+#ifdef SLAB_SUPPORTS_SYSFS
+		sysfs_slab_remove(s);
+#else
+		slab_kmem_cache_release(s);
+#endif
+	}
+}
+
+#ifdef CONFIG_MEMCG_KMEM
+/*
+ * memcg_create_kmem_cache - Create a cache for a memory cgroup.
+ * @memcg: The memory cgroup the new cache is for.
+ * @root_cache: The parent of the new cache.
+ *
+ * This function attempts to create a kmem cache that will serve allocation
+ * requests going from @memcg to @root_cache. The new cache inherits properties
+ * from its parent.
+ */
+void memcg_create_kmem_cache(struct mem_cgroup *memcg,
+			     struct kmem_cache *root_cache)
+{
+	static char memcg_name_buf[NAME_MAX + 1]; /* protected by slab_mutex */
+	struct cgroup_subsys_state *css = mem_cgroup_css(memcg);
+	struct memcg_cache_array *arr;
+	struct kmem_cache *s = NULL;
+	char *cache_name;
+	int idx;
+
+	get_online_cpus();
+	get_online_mems();
+
+	mutex_lock(&slab_mutex);
+
+	/*
+	 * The memory cgroup could have been deactivated while the cache
+	 * creation work was pending.
+	 */
+	if (!memcg_kmem_is_active(memcg))
+		goto out_unlock;
+
+	idx = memcg_cache_id(memcg);
+	arr = rcu_dereference_protected(root_cache->memcg_params.memcg_caches,
+					lockdep_is_held(&slab_mutex));
+
+	/*
+	 * Since per-memcg caches are created asynchronously on first
+	 * allocation (see memcg_kmem_get_cache()), several threads can try to
+	 * create the same cache, but only one of them may succeed.
+	 */
+	if (arr->entries[idx])
+		goto out_unlock;
+
+	cgroup_name(css->cgroup, memcg_name_buf, sizeof(memcg_name_buf));
+	cache_name = kasprintf(GFP_KERNEL, "%s(%d:%s)", root_cache->name,
+			       css->id, memcg_name_buf);
+	if (!cache_name)
+		goto out_unlock;
+
+	s = do_kmem_cache_create(cache_name, root_cache->object_size,
+				 root_cache->size, root_cache->align,
+				 root_cache->flags, root_cache->ctor,
+				 memcg, root_cache);
+	/*
+	 * If we could not create a memcg cache, do not complain, because
+	 * that's not critical at all as we can always proceed with the root
+	 * cache.
+	 */
+	if (IS_ERR(s)) {
+		kfree(cache_name);
+		goto out_unlock;
+	}
+
+	list_add(&s->memcg_params.list, &root_cache->memcg_params.list);
+
+	/*
+	 * Since readers won't lock (see cache_from_memcg_idx()), we need a
+	 * barrier here to ensure nobody will see the kmem_cache partially
+	 * initialized.
+	 */
+	smp_wmb();
+	arr->entries[idx] = s;
+
+out_unlock:
+	mutex_unlock(&slab_mutex);
+
+	put_online_mems();
+	put_online_cpus();
+}
+
+void memcg_deactivate_kmem_caches(struct mem_cgroup *memcg)
+{
+	int idx;
+	struct memcg_cache_array *arr;
+	struct kmem_cache *s, *c;
+
+	idx = memcg_cache_id(memcg);
+
+	get_online_cpus();
+	get_online_mems();
+
+	mutex_lock(&slab_mutex);
+	list_for_each_entry(s, &slab_caches, list) {
+		if (!is_root_cache(s))
+			continue;
+
+		arr = rcu_dereference_protected(s->memcg_params.memcg_caches,
+						lockdep_is_held(&slab_mutex));
+		c = arr->entries[idx];
+		if (!c)
+			continue;
+
+		__kmem_cache_shrink(c, true);
+		arr->entries[idx] = NULL;
+	}
+	mutex_unlock(&slab_mutex);
+
+	put_online_mems();
+	put_online_cpus();
+}
+
+void memcg_destroy_kmem_caches(struct mem_cgroup *memcg)
+{
+	LIST_HEAD(release);
+	bool need_rcu_barrier = false;
+	struct kmem_cache *s, *s2;
+
+	get_online_cpus();
+	get_online_mems();
+
+	mutex_lock(&slab_mutex);
+	list_for_each_entry_safe(s, s2, &slab_caches, list) {
+		if (is_root_cache(s) || s->memcg_params.memcg != memcg)
+			continue;
+		/*
+		 * The cgroup is about to be freed and therefore has no charges
+		 * left. Hence, all its caches must be empty by now.
+		 */
+		BUG_ON(do_kmem_cache_shutdown(s, &release, &need_rcu_barrier));
+	}
+	mutex_unlock(&slab_mutex);
+
+	put_online_mems();
+	put_online_cpus();
+
+	do_kmem_cache_release(&release, need_rcu_barrier);
+}
+#endif /* CONFIG_MEMCG_KMEM */
+
+void slab_kmem_cache_release(struct kmem_cache *s)
+{
+	destroy_memcg_params(s);
+	kfree_const(s->name);
+	kmem_cache_free(kmem_cache, s);
+}
+
+void kmem_cache_destroy(struct kmem_cache *s)
+{
+	struct kmem_cache *c, *c2;
+	LIST_HEAD(release);
+	bool need_rcu_barrier = false;
+	bool busy = false;
+
+	BUG_ON(!is_root_cache(s));
+
+	get_online_cpus();
+	get_online_mems();
+
+	mutex_lock(&slab_mutex);
+
+	s->refcount--;
+	if (s->refcount)
+		goto out_unlock;
+
+	for_each_memcg_cache_safe(c, c2, s) {
+		if (do_kmem_cache_shutdown(c, &release, &need_rcu_barrier))
+			busy = true;
+	}
+
+	if (!busy)
+		do_kmem_cache_shutdown(s, &release, &need_rcu_barrier);
+
+out_unlock:
+	mutex_unlock(&slab_mutex);
+
+	put_online_mems();
+	put_online_cpus();
+
+	do_kmem_cache_release(&release, need_rcu_barrier);
+}
+EXPORT_SYMBOL(kmem_cache_destroy);
+
+/**
+ * kmem_cache_shrink - Shrink a cache.
+ * @cachep: The cache to shrink.
+ *
+ * Releases as many slabs as possible for a cache.
+ * To help debugging, a zero exit status indicates all slabs were released.
+ */
+int kmem_cache_shrink(struct kmem_cache *cachep)
+{
+	int ret;
+
+	get_online_cpus();
+	get_online_mems();
+	ret = __kmem_cache_shrink(cachep, false);
+	put_online_mems();
+	put_online_cpus();
+	return ret;
+}
+EXPORT_SYMBOL(kmem_cache_shrink);
+
+int slab_is_available(void)
+{
+	return slab_state >= UP;
+}
+
+#ifndef CONFIG_SLOB
+/* Create a cache during boot when no slab services are available yet */
+void __init create_boot_cache(struct kmem_cache *s, const char *name, size_t size,
+		unsigned long flags)
+{
+	int err;
+
+	s->name = name;
+	s->size = s->object_size = size;
+	s->align = calculate_alignment(flags, ARCH_KMALLOC_MINALIGN, size);
+
+	slab_init_memcg_params(s);
+
+	err = __kmem_cache_create(s, flags);
+
+	if (err)
+		panic("Creation of kmalloc slab %s size=%zu failed. Reason %d\n",
+					name, size, err);
+
+	s->refcount = -1;	/* Exempt from merging for now */
+}
+
+struct kmem_cache *__init create_kmalloc_cache(const char *name, size_t size,
+				unsigned long flags)
+{
+	struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
+
+	if (!s)
+		panic("Out of memory when creating slab %s\n", name);
+
+	create_boot_cache(s, name, size, flags);
+	list_add(&s->list, &slab_caches);
+	s->refcount = 1;
+	return s;
+}
+
+struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
+EXPORT_SYMBOL(kmalloc_caches);
+
+#ifdef CONFIG_ZONE_DMA
+struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
+EXPORT_SYMBOL(kmalloc_dma_caches);
+#endif
+
+/*
+ * Conversion table for small slabs sizes / 8 to the index in the
+ * kmalloc array. This is necessary for slabs < 192 since we have non power
+ * of two cache sizes there. The size of larger slabs can be determined using
+ * fls.
+ */
+static s8 size_index[24] = {
+	3,	/* 8 */
+	4,	/* 16 */
+	5,	/* 24 */
+	5,	/* 32 */
+	6,	/* 40 */
+	6,	/* 48 */
+	6,	/* 56 */
+	6,	/* 64 */
+	1,	/* 72 */
+	1,	/* 80 */
+	1,	/* 88 */
+	1,	/* 96 */
+	7,	/* 104 */
+	7,	/* 112 */
+	7,	/* 120 */
+	7,	/* 128 */
+	2,	/* 136 */
+	2,	/* 144 */
+	2,	/* 152 */
+	2,	/* 160 */
+	2,	/* 168 */
+	2,	/* 176 */
+	2,	/* 184 */
+	2	/* 192 */
+};
+
+static inline int size_index_elem(size_t bytes)
+{
+	return (bytes - 1) / 8;
+}
+
+/*
+ * Find the kmem_cache structure that serves a given size of
+ * allocation
+ */
+struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
+{
+	int index;
+
+	if (unlikely(size > KMALLOC_MAX_SIZE)) {
+		WARN_ON_ONCE(!(flags & __GFP_NOWARN));
+		return NULL;
+	}
+
+	if (size <= 192) {
+		if (!size)
+			return ZERO_SIZE_PTR;
+
+		index = size_index[size_index_elem(size)];
+	} else
+		index = fls(size - 1);
+
+#ifdef CONFIG_ZONE_DMA
+	if (unlikely((flags & GFP_DMA)))
+		return kmalloc_dma_caches[index];
+
+#endif
+	return kmalloc_caches[index];
+}
+
+/*
+ * Create the kmalloc array. Some of the regular kmalloc arrays
+ * may already have been created because they were needed to
+ * enable allocations for slab creation.
+ */
+void __init create_kmalloc_caches(unsigned long flags)
+{
+	int i;
+
+	/*
+	 * 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
+	 */
+	BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
+		(KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
+
+	for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
+		int elem = size_index_elem(i);
+
+		if (elem >= ARRAY_SIZE(size_index))
+			break;
+		size_index[elem] = KMALLOC_SHIFT_LOW;
+	}
+
+	if (KMALLOC_MIN_SIZE >= 64) {
+		/*
+		 * The 96 byte size cache is not used if the alignment
+		 * is 64 byte.
+		 */
+		for (i = 64 + 8; i <= 96; i += 8)
+			size_index[size_index_elem(i)] = 7;
+
+	}
+
+	if (KMALLOC_MIN_SIZE >= 128) {
+		/*
+		 * The 192 byte sized cache is not used if the alignment
+		 * is 128 byte. Redirect kmalloc to use the 256 byte cache
+		 * instead.
+		 */
+		for (i = 128 + 8; i <= 192; i += 8)
+			size_index[size_index_elem(i)] = 8;
+	}
+	for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
+		if (!kmalloc_caches[i]) {
+			kmalloc_caches[i] = create_kmalloc_cache(NULL,
+							1 << i, flags);
+		}
+
+		/*
+		 * Caches that are not of the two-to-the-power-of size.
+		 * These have to be created immediately after the
+		 * earlier power of two caches
+		 */
+		if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1] && i == 6)
+			kmalloc_caches[1] = create_kmalloc_cache(NULL, 96, flags);
+
+		if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2] && i == 7)
+			kmalloc_caches[2] = create_kmalloc_cache(NULL, 192, flags);
+	}
+
+	/* Kmalloc array is now usable */
+	slab_state = UP;
+
+	for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
+		struct kmem_cache *s = kmalloc_caches[i];
+		char *n;
+
+		if (s) {
+			n = kasprintf(GFP_NOWAIT, "kmalloc-%d", kmalloc_size(i));
+
+			BUG_ON(!n);
+			s->name = n;
+		}
+	}
+
+#ifdef CONFIG_ZONE_DMA
+	for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
+		struct kmem_cache *s = kmalloc_caches[i];
+
+		if (s) {
+			int size = kmalloc_size(i);
+			char *n = kasprintf(GFP_NOWAIT,
+				 "dma-kmalloc-%d", size);
+
+			BUG_ON(!n);
+			kmalloc_dma_caches[i] = create_kmalloc_cache(n,
+				size, SLAB_CACHE_DMA | flags);
+		}
+	}
+#endif
+}
+#endif /* !CONFIG_SLOB */
+
+/*
+ * To avoid unnecessary overhead, we pass through large allocation requests
+ * directly to the page allocator. We use __GFP_COMP, because we will need to
+ * know the allocation order to free the pages properly in kfree.
+ */
+void *kmalloc_order(size_t size, gfp_t flags, unsigned int order)
+{
+	void *ret;
+	struct page *page;
+
+	flags |= __GFP_COMP;
+	page = alloc_kmem_pages(flags, order);
+	ret = page ? page_address(page) : NULL;
+	kmemleak_alloc(ret, size, 1, flags);
+	kasan_kmalloc_large(ret, size);
+	return ret;
+}
+EXPORT_SYMBOL(kmalloc_order);
+
+#ifdef CONFIG_TRACING
+void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
+{
+	void *ret = kmalloc_order(size, flags, order);
+	trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags);
+	return ret;
+}
+EXPORT_SYMBOL(kmalloc_order_trace);
+#endif
+
+#ifdef CONFIG_SLABINFO
+
+#ifdef CONFIG_SLAB
+#define SLABINFO_RIGHTS (S_IWUSR | S_IRUSR)
+#else
+#define SLABINFO_RIGHTS S_IRUSR
+#endif
+
+static void print_slabinfo_header(struct seq_file *m)
+{
+	/*
+	 * Output format version, so at least we can change it
+	 * without _too_ many complaints.
+	 */
+#ifdef CONFIG_DEBUG_SLAB
+	seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
+#else
+	seq_puts(m, "slabinfo - version: 2.1\n");
+#endif
+	seq_puts(m, "# name            <active_objs> <num_objs> <objsize> "
+		 "<objperslab> <pagesperslab>");
+	seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
+	seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
+#ifdef CONFIG_DEBUG_SLAB
+	seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> "
+		 "<error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
+	seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
+#endif
+	seq_putc(m, '\n');
+}
+
+void *slab_start(struct seq_file *m, loff_t *pos)
+{
+	mutex_lock(&slab_mutex);
+	return seq_list_start(&slab_caches, *pos);
+}
+
+void *slab_next(struct seq_file *m, void *p, loff_t *pos)
+{
+	return seq_list_next(p, &slab_caches, pos);
+}
+
+void slab_stop(struct seq_file *m, void *p)
+{
+	mutex_unlock(&slab_mutex);
+}
+
+static void
+memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info)
+{
+	struct kmem_cache *c;
+	struct slabinfo sinfo;
+
+	if (!is_root_cache(s))
+		return;
+
+	for_each_memcg_cache(c, s) {
+		memset(&sinfo, 0, sizeof(sinfo));
+		get_slabinfo(c, &sinfo);
+
+		info->active_slabs += sinfo.active_slabs;
+		info->num_slabs += sinfo.num_slabs;
+		info->shared_avail += sinfo.shared_avail;
+		info->active_objs += sinfo.active_objs;
+		info->num_objs += sinfo.num_objs;
+	}
+}
+
+static void cache_show(struct kmem_cache *s, struct seq_file *m)
+{
+	struct slabinfo sinfo;
+
+	memset(&sinfo, 0, sizeof(sinfo));
+	get_slabinfo(s, &sinfo);
+
+	memcg_accumulate_slabinfo(s, &sinfo);
+
+	seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
+		   cache_name(s), sinfo.active_objs, sinfo.num_objs, s->size,
+		   sinfo.objects_per_slab, (1 << sinfo.cache_order));
+
+	seq_printf(m, " : tunables %4u %4u %4u",
+		   sinfo.limit, sinfo.batchcount, sinfo.shared);
+	seq_printf(m, " : slabdata %6lu %6lu %6lu",
+		   sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
+	slabinfo_show_stats(m, s);
+	seq_putc(m, '\n');
+}
+
+static int slab_show(struct seq_file *m, void *p)
+{
+	struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
+
+	if (p == slab_caches.next)
+		print_slabinfo_header(m);
+	if (is_root_cache(s))
+		cache_show(s, m);
+	return 0;
+}
+
+#ifdef CONFIG_MEMCG_KMEM
+int memcg_slab_show(struct seq_file *m, void *p)
+{
+	struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
+	struct mem_cgroup *memcg = mem_cgroup_from_css(seq_css(m));
+
+	if (p == slab_caches.next)
+		print_slabinfo_header(m);
+	if (!is_root_cache(s) && s->memcg_params.memcg == memcg)
+		cache_show(s, m);
+	return 0;
+}
+#endif
+
+/*
+ * slabinfo_op - iterator that generates /proc/slabinfo
+ *
+ * Output layout:
+ * cache-name
+ * num-active-objs
+ * total-objs
+ * object size
+ * num-active-slabs
+ * total-slabs
+ * num-pages-per-slab
+ * + further values on SMP and with statistics enabled
+ */
+static const struct seq_operations slabinfo_op = {
+	.start = slab_start,
+	.next = slab_next,
+	.stop = slab_stop,
+	.show = slab_show,
+};
+
+static int slabinfo_open(struct inode *inode, struct file *file)
+{
+	return seq_open(file, &slabinfo_op);
+}
+
+static const struct file_operations proc_slabinfo_operations = {
+	.open		= slabinfo_open,
+	.read		= seq_read,
+	.write          = slabinfo_write,
+	.llseek		= seq_lseek,
+	.release	= seq_release,
+};
+
+static int __init slab_proc_init(void)
+{
+	proc_create("slabinfo", SLABINFO_RIGHTS, NULL,
+						&proc_slabinfo_operations);
+	return 0;
+}
+module_init(slab_proc_init);
+#endif /* CONFIG_SLABINFO */
+
+static __always_inline void *__do_krealloc(const void *p, size_t new_size,
+					   gfp_t flags)
+{
+	void *ret;
+	size_t ks = 0;
+
+	if (p)
+		ks = ksize(p);
+
+	if (ks >= new_size) {
+		kasan_krealloc((void *)p, new_size);
+		return (void *)p;
+	}
+
+	ret = kmalloc_track_caller(new_size, flags);
+	if (ret && p)
+		memcpy(ret, p, ks);
+
+	return ret;
+}
+
+/**
+ * __krealloc - like krealloc() but don't free @p.
+ * @p: object to reallocate memory for.
+ * @new_size: how many bytes of memory are required.
+ * @flags: the type of memory to allocate.
+ *
+ * This function is like krealloc() except it never frees the originally
+ * allocated buffer. Use this if you don't want to free the buffer immediately
+ * like, for example, with RCU.
+ */
+void *__krealloc(const void *p, size_t new_size, gfp_t flags)
+{
+	if (unlikely(!new_size))
+		return ZERO_SIZE_PTR;
+
+	return __do_krealloc(p, new_size, flags);
+
+}
+EXPORT_SYMBOL(__krealloc);
+
+/**
+ * krealloc - reallocate memory. The contents will remain unchanged.
+ * @p: object to reallocate memory for.
+ * @new_size: how many bytes of memory are required.
+ * @flags: the type of memory to allocate.
+ *
+ * The contents of the object pointed to are preserved up to the
+ * lesser of the new and old sizes.  If @p is %NULL, krealloc()
+ * behaves exactly like kmalloc().  If @new_size is 0 and @p is not a
+ * %NULL pointer, the object pointed to is freed.
+ */
+void *krealloc(const void *p, size_t new_size, gfp_t flags)
+{
+	void *ret;
+
+	if (unlikely(!new_size)) {
+		kfree(p);
+		return ZERO_SIZE_PTR;
+	}
+
+	ret = __do_krealloc(p, new_size, flags);
+	if (ret && p != ret)
+		kfree(p);
+
+	return ret;
+}
+EXPORT_SYMBOL(krealloc);
+
+/**
+ * kzfree - like kfree but zero memory
+ * @p: object to free memory of
+ *
+ * The memory of the object @p points to is zeroed before freed.
+ * If @p is %NULL, kzfree() does nothing.
+ *
+ * Note: this function zeroes the whole allocated buffer which can be a good
+ * deal bigger than the requested buffer size passed to kmalloc(). So be
+ * careful when using this function in performance sensitive code.
+ */
+void kzfree(const void *p)
+{
+	size_t ks;
+	void *mem = (void *)p;
+
+	if (unlikely(ZERO_OR_NULL_PTR(mem)))
+		return;
+	ks = ksize(mem);
+	memset(mem, 0, ks);
+	kfree(mem);
+}
+EXPORT_SYMBOL(kzfree);
+
+/* Tracepoints definitions. */
+EXPORT_TRACEPOINT_SYMBOL(kmalloc);
+EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc);
+EXPORT_TRACEPOINT_SYMBOL(kmalloc_node);
+EXPORT_TRACEPOINT_SYMBOL(kmem_cache_alloc_node);
+EXPORT_TRACEPOINT_SYMBOL(kfree);
+EXPORT_TRACEPOINT_SYMBOL(kmem_cache_free);