text: // SPDX-License-Identifier: GPL-2.0
  /*
   * SLUB: A slab allocator that limits cache line use instead of queuing
   * objects in per cpu and per node lists.
   *
   * The allocator synchronizes using per slab locks or atomic operatios
   * and only uses a centralized lock to manage a pool of partial slabs.
   *
   * (C) 2007 SGI, Christoph Lameter
   * (C) 2011 Linux Foundation, Christoph Lameter
   */
  
  #include <linux/mm.h>
  #include <linux/swap.h> /* struct reclaim_state */
  #include <linux/module.h>
  #include <linux/bit_spinlock.h>
  #include <linux/interrupt.h>
  #include <linux/bitops.h>
  #include <linux/slab.h>
  #include "slab.h"
  #include <linux/proc_fs.h>
  #include <linux/notifier.h>
  #include <linux/seq_file.h>
  #include <linux/kasan.h>
  #include <linux/cpu.h>
  #include <linux/cpuset.h>
  #include <linux/mempolicy.h>
  #include <linux/ctype.h>
  #include <linux/debugobjects.h>
  #include <linux/kallsyms.h>
  #include <linux/memory.h>
  #include <linux/math64.h>
  #include <linux/fault-inject.h>
  #include <linux/stacktrace.h>
  #include <linux/prefetch.h>
  #include <linux/memcontrol.h>
  #include <linux/random.h>
  
  #include <trace/events/kmem.h>
  
  #include "internal.h"
  
  /*
   * Lock order:
   *   1. slab_mutex (Global Mutex)
   *   2. node->list_lock
   *   3. slab_lock(page) (Only on some arches and for debugging)
   *
   *   slab_mutex
   *
   *   The role of the slab_mutex is to protect the list of all the slabs
   *   and to synchronize major metadata changes to slab cache structures.
   *
   *   The slab_lock is only used for debugging and on arches that do not
   *   have the ability to do a cmpxchg_double. It only protects the second
   *   double word in the page struct. Meaning
   *	A. page->freelist	-> List of object free in a page
   *	B. page->counters	-> Counters of objects
   *	C. page->frozen		-> frozen state
   *
   *   If a slab is frozen then it is exempt from list management. It is not
   *   on any list. The processor that froze the slab is the one who can
   *   perform list operations on the page. Other processors may put objects
   *   onto the freelist but the processor that froze the slab is the only
   *   one that can retrieve the objects from the page's freelist.
   *
   *   The list_lock protects the partial and full list on each node and
   *   the partial slab counter. If taken then no new slabs may be added or
   *   removed from the lists nor make the number of partial slabs be modified.
   *   (Note that the total number of slabs is an atomic value that may be
   *   modified without taking the list lock).
   *
   *   The list_lock is a centralized lock and thus we avoid taking it as
   *   much as possible. As long as SLUB does not have to handle partial
   *   slabs, operations can continue without any centralized lock. F.e.
   *   allocating a long series of objects that fill up slabs does not require
   *   the list lock.
   *   Interrupts are disabled during allocation and deallocation in order to
   *   make the slab allocator safe to use in the context of an irq. In addition
   *   interrupts are disabled to ensure that the processor does not change
   *   while handling per_cpu slabs, due to kernel preemption.
   *
   * SLUB assigns one slab for allocation to each processor.
   * Allocations only occur from these slabs called cpu slabs.
   *
   * Slabs with free elements are kept on a partial list and during regular
   * operations no list for full slabs is used. If an object in a full slab is
   * freed then the slab will show up again on the partial lists.
   * We track full slabs for debugging purposes though because otherwise we
   * cannot scan all objects.
   *
   * Slabs are freed when they become empty. Teardown and setup is
   * minimal so we rely on the page allocators per cpu caches for
   * fast frees and allocs.
   *
   * Overloading of page flags that are otherwise used for LRU management.
   *
   * PageActive 		The slab is frozen and exempt from list processing.
   * 			This means that the slab is dedicated to a purpose
   * 			such as satisfying allocations for a specific
   * 			processor. Objects may be freed in the slab while
   * 			it is frozen but slab_free will then skip the usual
   * 			list operations. It is up to the processor holding
   * 			the slab to integrate the slab into the slab lists
   * 			when the slab is no longer needed.
   *
   * 			One use of this flag is to mark slabs that are
   * 			used for allocations. Then such a slab becomes a cpu
   * 			slab. The cpu slab may be equipped with an additional
   * 			freelist that allows lockless access to
   * 			free objects in addition to the regular freelist
   * 			that requires the slab lock.
   *
   * PageError		Slab requires special handling due to debug
   * 			options set. This moves	slab handling out of
   * 			the fast path and disables lockless freelists.
   */
  
  static inline int kmem_cache_debug(struct kmem_cache *s)
  {
  #ifdef CONFIG_SLUB_DEBUG
  	return unlikely(s->flags & SLAB_DEBUG_FLAGS);
  #else
  	return 0;
  #endif
  }
  
  void *fixup_red_left(struct kmem_cache *s, void *p)
  {
  	if (kmem_cache_debug(s) && s->flags & SLAB_RED_ZONE)
  		p += s->red_left_pad;
  
  	return p;
  }
  
  static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s)
  {
  #ifdef CONFIG_SLUB_CPU_PARTIAL
  	return !kmem_cache_debug(s);
  #else
  	return false;
  #endif
  }
  
  /*
   * Issues still to be resolved:
   *
   * - Support PAGE_ALLOC_DEBUG. Should be easy to do.
   *
   * - Variable sizing of the per node arrays
   */
  
  /* Enable to test recovery from slab corruption on boot */
  #undef SLUB_RESILIENCY_TEST
  
  /* Enable to log cmpxchg failures */
  #undef SLUB_DEBUG_CMPXCHG
  
  /*
   * Mininum number of partial slabs. These will be left on the partial
   * lists even if they are empty. kmem_cache_shrink may reclaim them.
   */
  #define MIN_PARTIAL 5
  
  /*
   * Maximum number of desirable partial slabs.
   * The existence of more partial slabs makes kmem_cache_shrink
   * sort the partial list by the number of objects in use.
   */
  #define MAX_PARTIAL 10
  
  #define DEBUG_DEFAULT_FLAGS (SLAB_CONSISTENCY_CHECKS | SLAB_RED_ZONE | \
  				SLAB_POISON | SLAB_STORE_USER)
  
  /*
   * These debug flags cannot use CMPXCHG because there might be consistency
   * issues when checking or reading debug information
   */
  #define SLAB_NO_CMPXCHG (SLAB_CONSISTENCY_CHECKS | SLAB_STORE_USER | \
  				SLAB_TRACE)
  
  
  /*
   * Debugging flags that require metadata to be stored in the slab.  These get
   * disabled when slub_debug=O is used and a cache's min order increases with
   * metadata.
   */
  #define DEBUG_METADATA_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)
  
  #define OO_SHIFT	16
  #define OO_MASK		((1 << OO_SHIFT) - 1)
  #define MAX_OBJS_PER_PAGE	32767 /* since page.objects is u15 */
  
  /* Internal SLUB flags */
  /* Poison object */
  #define __OBJECT_POISON		((slab_flags_t __force)0x80000000U)
  /* Use cmpxchg_double */
  #define __CMPXCHG_DOUBLE	((slab_flags_t __force)0x40000000U)
  
  /*
   * Tracking user of a slab.
   */
  #define TRACK_ADDRS_COUNT 16
  struct track {
  	unsigned long addr;	/* Called from address */
  #ifdef CONFIG_STACKTRACE
  	unsigned long addrs[TRACK_ADDRS_COUNT];	/* Called from address */
  #endif
  	int cpu;		/* Was running on cpu */
  	int pid;		/* Pid context */
  	unsigned long when;	/* When did the operation occur */
  };
  
  enum track_item { TRACK_ALLOC, TRACK_FREE };
  
  #ifdef CONFIG_SYSFS
  static int sysfs_slab_add(struct kmem_cache *);
  static int sysfs_slab_alias(struct kmem_cache *, const char *);
  static void memcg_propagate_slab_attrs(struct kmem_cache *s);
  static void sysfs_slab_remove(struct kmem_cache *s);
  #else
  static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; }
  static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p)
  							{ return 0; }
  static inline void memcg_propagate_slab_attrs(struct kmem_cache *s) { }
  static inline void sysfs_slab_remove(struct kmem_cache *s) { }
  #endif
  
  static inline void stat(const struct kmem_cache *s, enum stat_item si)
  {
  #ifdef CONFIG_SLUB_STATS
  	/*
  	 * The rmw is racy on a preemptible kernel but this is acceptable, so
  	 * avoid this_cpu_add()'s irq-disable overhead.
  	 */
  	raw_cpu_inc(s->cpu_slab->stat[si]);
  #endif
  }
  
  /********************************************************************
   * 			Core slab cache functions
   *******************************************************************/
  
  /*
   * Returns freelist pointer (ptr). With hardening, this is obfuscated
   * with an XOR of the address where the pointer is held and a per-cache
   * random number.
   */
  static inline void *freelist_ptr(const struct kmem_cache *s, void *ptr,
  				 unsigned long ptr_addr)
  {
  #ifdef CONFIG_SLAB_FREELIST_HARDENED
  	return (void *)((unsigned long)ptr ^ s->random ^ ptr_addr);
  #else
  	return ptr;
  #endif
  }
  
  /* Returns the freelist pointer recorded at location ptr_addr. */
  static inline void *freelist_dereference(const struct kmem_cache *s,
  					 void *ptr_addr)
  {
  	return freelist_ptr(s, (void *)*(unsigned long *)(ptr_addr),
  			    (unsigned long)ptr_addr);
  }
  
  static inline void *get_freepointer(struct kmem_cache *s, void *object)
  {
  	return freelist_dereference(s, object + s->offset);
  }
  
  static void prefetch_freepointer(const struct kmem_cache *s, void *object)
  {
  	if (object)
  		prefetch(freelist_dereference(s, object + s->offset));
  }
  
  static inline void *get_freepointer_safe(struct kmem_cache *s, void *object)
  {
  	unsigned long freepointer_addr;
  	void *p;
  
  	if (!debug_pagealloc_enabled())
  		return get_freepointer(s, object);
  
  	freepointer_addr = (unsigned long)object + s->offset;
  	probe_kernel_read(&p, (void **)freepointer_addr, sizeof(p));
  	return freelist_ptr(s, p, freepointer_addr);
  }
  
  static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp)
  {
  	unsigned long freeptr_addr = (unsigned long)object + s->offset;
  
  #ifdef CONFIG_SLAB_FREELIST_HARDENED
  	BUG_ON(object == fp); /* naive detection of double free or corruption */
  #endif
  
  	*(void **)freeptr_addr = freelist_ptr(s, fp, freeptr_addr);
  }
  
  /* Loop over all objects in a slab */
  #define for_each_object(__p, __s, __addr, __objects) \
  	for (__p = fixup_red_left(__s, __addr); \
  		__p < (__addr) + (__objects) * (__s)->size; \
  		__p += (__s)->size)
  
  #define for_each_object_idx(__p, __idx, __s, __addr, __objects) \
  	for (__p = fixup_red_left(__s, __addr), __idx = 1; \
  		__idx <= __objects; \
  		__p += (__s)->size, __idx++)
  
  /* Determine object index from a given position */
  static inline unsigned int slab_index(void *p, struct kmem_cache *s, void *addr)
  {
  	return (p - addr) / s->size;
  }
  
  static inline unsigned int order_objects(unsigned int order, unsigned int size, unsigned int reserved)
  {
  	return (((unsigned int)PAGE_SIZE << order) - reserved) / size;
  }
  
  static inline struct kmem_cache_order_objects oo_make(unsigned int order,
  		unsigned int size, unsigned int reserved)
  {
  	struct kmem_cache_order_objects x = {
  		(order << OO_SHIFT) + order_objects(order, size, reserved)
  	};
  
  	return x;
  }
  
  static inline unsigned int oo_order(struct kmem_cache_order_objects x)
  {
  	return x.x >> OO_SHIFT;
  }
  
  static inline unsigned int oo_objects(struct kmem_cache_order_objects x)
  {
  	return x.x & OO_MASK;
  }
  
  /*
   * Per slab locking using the pagelock
   */
  static __always_inline void slab_lock(struct page *page)
  {
  	VM_BUG_ON_PAGE(PageTail(page), page);
  	bit_spin_lock(PG_locked, &page->flags);
  }
  
  static __always_inline void slab_unlock(struct page *page)
  {
  	VM_BUG_ON_PAGE(PageTail(page), page);
  	__bit_spin_unlock(PG_locked, &page->flags);
  }
  
  static inline void set_page_slub_counters(struct page *page, unsigned long counters_new)
  {
  	struct page tmp;
  	tmp.counters = counters_new;
  	/*
  	 * page->counters can cover frozen/inuse/objects as well
  	 * as page->_refcount.  If we assign to ->counters directly
  	 * we run the risk of losing updates to page->_refcount, so
  	 * be careful and only assign to the fields we need.
  	 */
  	page->frozen  = tmp.frozen;
  	page->inuse   = tmp.inuse;
  	page->objects = tmp.objects;
  }
  
  /* Interrupts must be disabled (for the fallback code to work right) */
  static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
  		void *freelist_old, unsigned long counters_old,
  		void *freelist_new, unsigned long counters_new,
  		const char *n)
  {
  	VM_BUG_ON(!irqs_disabled());
  #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
      defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
  	if (s->flags & __CMPXCHG_DOUBLE) {
  		if (cmpxchg_double(&page->freelist, &page->counters,
  				   freelist_old, counters_old,
  				   freelist_new, counters_new))
  			return true;
  	} else
  #endif
  	{
  		slab_lock(page);
  		if (page->freelist == freelist_old &&
  					page->counters == counters_old) {
  			page->freelist = freelist_new;
  			set_page_slub_counters(page, counters_new);
  			slab_unlock(page);
  			return true;
  		}
  		slab_unlock(page);
  	}
  
  	cpu_relax();
  	stat(s, CMPXCHG_DOUBLE_FAIL);
  
  #ifdef SLUB_DEBUG_CMPXCHG
  	pr_info("%s %s: cmpxchg double redo ", n, s->name);
  #endif
  
  	return false;
  }
  
  static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
  		void *freelist_old, unsigned long counters_old,
  		void *freelist_new, unsigned long counters_new,
  		const char *n)
  {
  #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
      defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
  	if (s->flags & __CMPXCHG_DOUBLE) {
  		if (cmpxchg_double(&page->freelist, &page->counters,
  				   freelist_old, counters_old,
  				   freelist_new, counters_new))
  			return true;
  	} else
  #endif
  	{
  		unsigned long flags;
  
  		local_irq_save(flags);
  		slab_lock(page);
  		if (page->freelist == freelist_old &&
  					page->counters == counters_old) {
  			page->freelist = freelist_new;
  			set_page_slub_counters(page, counters_new);
  			slab_unlock(page);
  			local_irq_restore(flags);
  			return true;
  		}
  		slab_unlock(page);
  		local_irq_restore(flags);
  	}
  
  	cpu_relax();
  	stat(s, CMPXCHG_DOUBLE_FAIL);
  
  #ifdef SLUB_DEBUG_CMPXCHG
  	pr_info("%s %s: cmpxchg double redo ", n, s->name);
  #endif
  
  	return false;
  }
  
  #ifdef CONFIG_SLUB_DEBUG
  /*
   * Determine a map of object in use on a page.
   *
   * Node listlock must be held to guarantee that the page does
   * not vanish from under us.
   */
  static void get_map(struct kmem_cache *s, struct page *page, unsigned long *map)
  {
  	void *p;
  	void *addr = page_address(page);
  
  	for (p = page->freelist; p; p = get_freepointer(s, p))
  		set_bit(slab_index(p, s, addr), map);
  }
  
  static inline unsigned int size_from_object(struct kmem_cache *s)
  {
  	if (s->flags & SLAB_RED_ZONE)
  		return s->size - s->red_left_pad;
  
  	return s->size;
  }
  
  static inline void *restore_red_left(struct kmem_cache *s, void *p)
  {
  	if (s->flags & SLAB_RED_ZONE)
  		p -= s->red_left_pad;
  
  	return p;
  }
  
  /*
   * Debug settings:
   */
  #if defined(CONFIG_SLUB_DEBUG_ON)
  static slab_flags_t slub_debug = DEBUG_DEFAULT_FLAGS;
  #else
  static slab_flags_t slub_debug;
  #endif
  
  static char *slub_debug_slabs;
  static int disable_higher_order_debug;
  
  /*
   * slub is about to manipulate internal object metadata.  This memory lies
   * outside the range of the allocated object, so accessing it would normally
   * be reported by kasan as a bounds error.  metadata_access_enable() is used
   * to tell kasan that these accesses are OK.
   */
  static inline void metadata_access_enable(void)
  {
  	kasan_disable_current();
  }
  
  static inline void metadata_access_disable(void)
  {
  	kasan_enable_current();
  }
  
  /*
   * Object debugging
   */
  
  /* Verify that a pointer has an address that is valid within a slab page */
  static inline int check_valid_pointer(struct kmem_cache *s,
  				struct page *page, void *object)
  {
  	void *base;
  
  	if (!object)
  		return 1;
  
  	base = page_address(page);
  	object = restore_red_left(s, object);
  	if (object < base || object >= base + page->objects * s->size ||
  		(object - base) % s->size) {
  		return 0;
  	}
  
  	return 1;
  }
  
  static void print_section(char *level, char *text, u8 *addr,
  			  unsigned int length)
  {
  	metadata_access_enable();
  	print_hex_dump(level, text, DUMP_PREFIX_ADDRESS, 16, 1, addr,
  			length, 1);
  	metadata_access_disable();
  }
  
  static struct track *get_track(struct kmem_cache *s, void *object,
  	enum track_item alloc)
  {
  	struct track *p;
  
  	if (s->offset)
  		p = object + s->offset + sizeof(void *);
  	else
  		p = object + s->inuse;
  
  	return p + alloc;
  }
  
  static void set_track(struct kmem_cache *s, void *object,
  			enum track_item alloc, unsigned long addr)
  {
  	struct track *p = get_track(s, object, alloc);
  
  	if (addr) {
  #ifdef CONFIG_STACKTRACE
  		struct stack_trace trace;
  		int i;
  
  		trace.nr_entries = 0;
  		trace.max_entries = TRACK_ADDRS_COUNT;
  		trace.entries = p->addrs;
  		trace.skip = 3;
  		metadata_access_enable();
  		save_stack_trace(&trace);
  		metadata_access_disable();
  
  		/* See rant in lockdep.c */
  		if (trace.nr_entries != 0 &&
  		    trace.entries[trace.nr_entries - 1] == ULONG_MAX)
  			trace.nr_entries--;
  
  		for (i = trace.nr_entries; i < TRACK_ADDRS_COUNT; i++)
  			p->addrs[i] = 0;
  #endif
  		p->addr = addr;
  		p->cpu = smp_processor_id();
  		p->pid = current->pid;
  		p->when = jiffies;
  	} else
  		memset(p, 0, sizeof(struct track));
  }
  
  static void init_tracking(struct kmem_cache *s, void *object)
  {
  	if (!(s->flags & SLAB_STORE_USER))
  		return;
  
  	set_track(s, object, TRACK_FREE, 0UL);
  	set_track(s, object, TRACK_ALLOC, 0UL);
  }
  
  static void print_track(const char *s, struct track *t, unsigned long pr_time)
  {
  	if (!t->addr)
  		return;
  
  	pr_err("INFO: %s in %pS age=%lu cpu=%u pid=%d\n",
  	       s, (void *)t->addr, pr_time - t->when, t->cpu, t->pid);
  #ifdef CONFIG_STACKTRACE
  	{
  		int i;
  		for (i = 0; i < TRACK_ADDRS_COUNT; i++)
  			if (t->addrs[i])
  				pr_err("\t%pS\n", (void *)t->addrs[i]);
  			else
  				break;
  	}
  #endif
  }
  
  static void print_tracking(struct kmem_cache *s, void *object)
  {
  	unsigned long pr_time = jiffies;
  	if (!(s->flags & SLAB_STORE_USER))
  		return;
  
  	print_track("Allocated", get_track(s, object, TRACK_ALLOC), pr_time);
  	print_track("Freed", get_track(s, object, TRACK_FREE), pr_time);
  }
  
  static void print_page_info(struct page *page)
  {
  	pr_err("INFO: Slab 0x%p objects=%u used=%u fp=0x%p flags=0x%04lx\n",
  	       page, page->objects, page->inuse, page->freelist, page->flags);
  
  }
  
  static void slab_bug(struct kmem_cache *s, char *fmt, ...)
  {
  	struct va_format vaf;
  	va_list args;
  
  	va_start(args, fmt);
  	vaf.fmt = fmt;
  	vaf.va = &args;
  	pr_err("=============================================================================\n");
  	pr_err("BUG %s (%s): %pV\n", s->name, print_tainted(), &vaf);
  	pr_err("-----------------------------------------------------------------------------\n\n");
  
  	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
  	va_end(args);
  }
  
  static void slab_fix(struct kmem_cache *s, char *fmt, ...)
  {
  	struct va_format vaf;
  	va_list args;
  
  	va_start(args, fmt);
  	vaf.fmt = fmt;
  	vaf.va = &args;
  	pr_err("FIX %s: %pV\n", s->name, &vaf);
  	va_end(args);
  }
  
  static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
  {
  	unsigned int off;	/* Offset of last byte */
  	u8 *addr = page_address(page);
  
  	print_tracking(s, p);
  
  	print_page_info(page);
  
  	pr_err("INFO: Object 0x%p @offset=%tu fp=0x%p\n\n",
  	       p, p - addr, get_freepointer(s, p));
  
  	if (s->flags & SLAB_RED_ZONE)
  		print_section(KERN_ERR, "Redzone ", p - s->red_left_pad,
  			      s->red_left_pad);
  	else if (p > addr + 16)
  		print_section(KERN_ERR, "Bytes b4 ", p - 16, 16);
  
  	print_section(KERN_ERR, "Object ", p,
  		      min_t(unsigned int, s->object_size, PAGE_SIZE));
  	if (s->flags & SLAB_RED_ZONE)
  		print_section(KERN_ERR, "Redzone ", p + s->object_size,
  			s->inuse - s->object_size);
  
  	if (s->offset)
  		off = s->offset + sizeof(void *);
  	else
  		off = s->inuse;
  
  	if (s->flags & SLAB_STORE_USER)
  		off += 2 * sizeof(struct track);
  
  	off += kasan_metadata_size(s);
  
  	if (off != size_from_object(s))
  		/* Beginning of the filler is the free pointer */
  		print_section(KERN_ERR, "Padding ", p + off,
  			      size_from_object(s) - off);
  
  	dump_stack();
  }
  
  void object_err(struct kmem_cache *s, struct page *page,
  			u8 *object, char *reason)
  {
  	slab_bug(s, "%s", reason);
  	print_trailer(s, page, object);
  }
  
  static void slab_err(struct kmem_cache *s, struct page *page,
  			const char *fmt, ...)
  {
  	va_list args;
  	char buf[100];
  
  	va_start(args, fmt);
  	vsnprintf(buf, sizeof(buf), fmt, args);
  	va_end(args);
  	slab_bug(s, "%s", buf);
  	print_page_info(page);
  	dump_stack();
  }
  
  static void init_object(struct kmem_cache *s, void *object, u8 val)
  {
  	u8 *p = object;
  
  	if (s->flags & SLAB_RED_ZONE)
  		memset(p - s->red_left_pad, val, s->red_left_pad);
  
  	if (s->flags & __OBJECT_POISON) {
  		memset(p, POISON_FREE, s->object_size - 1);
  		p[s->object_size - 1] = POISON_END;
  	}
  
  	if (s->flags & SLAB_RED_ZONE)
  		memset(p + s->object_size, val, s->inuse - s->object_size);
  }
  
  static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
  						void *from, void *to)
  {
  	slab_fix(s, "Restoring 0x%p-0x%p=0x%x\n", from, to - 1, data);
  	memset(from, data, to - from);
  }
  
  static int check_bytes_and_report(struct kmem_cache *s, struct page *page,
  			u8 *object, char *what,
  			u8 *start, unsigned int value, unsigned int bytes)
  {
  	u8 *fault;
  	u8 *end;
  
  	metadata_access_enable();
  	fault = memchr_inv(start, value, bytes);
  	metadata_access_disable();
  	if (!fault)
  		return 1;
  
  	end = start + bytes;
  	while (end > fault && end[-1] == value)
  		end--;
  
  	slab_bug(s, "%s overwritten", what);
  	pr_err("INFO: 0x%p-0x%p. First byte 0x%x instead of 0x%x\n",
  					fault, end - 1, fault[0], value);
  	print_trailer(s, page, object);
  
  	restore_bytes(s, what, value, fault, end);
  	return 0;
  }
  
  /*
   * Object layout:
   *
   * object address
   * 	Bytes of the object to be managed.
   * 	If the freepointer may overlay the object then the free
   * 	pointer is the first word of the object.
   *
   * 	Poisoning uses 0x6b (POISON_FREE) and the last byte is
   * 	0xa5 (POISON_END)
   *
   * object + s->object_size
   * 	Padding to reach word boundary. This is also used for Redzoning.
   * 	Padding is extended by another word if Redzoning is enabled and
   * 	object_size == inuse.
   *
   * 	We fill with 0xbb (RED_INACTIVE) for inactive objects and with
   * 	0xcc (RED_ACTIVE) for objects in use.
   *
   * object + s->inuse
   * 	Meta data starts here.
   *
   * 	A. Free pointer (if we cannot overwrite object on free)
   * 	B. Tracking data for SLAB_STORE_USER
   * 	C. Padding to reach required alignment boundary or at mininum
   * 		one word if debugging is on to be able to detect writes
   * 		before the word boundary.
   *
   *	Padding is done using 0x5a (POISON_INUSE)
   *
   * object + s->size
   * 	Nothing is used beyond s->size.
   *
   * If slabcaches are merged then the object_size and inuse boundaries are mostly
   * ignored. And therefore no slab options that rely on these boundaries
   * may be used with merged slabcaches.
   */
  
  static int check_pad_bytes(struct kmem_cache *s, struct page *page, u8 *p)
  {
  	unsigned long off = s->inuse;	/* The end of info */
  
  	if (s->offset)
  		/* Freepointer is placed after the object. */
  		off += sizeof(void *);
  
  	if (s->flags & SLAB_STORE_USER)
  		/* We also have user information there */
  		off += 2 * sizeof(struct track);
  
  	off += kasan_metadata_size(s);
  
  	if (size_from_object(s) == off)
  		return 1;
  
  	return check_bytes_and_report(s, page, p, "Object padding",
  			p + off, POISON_INUSE, size_from_object(s) - off);
  }
  
  /* Check the pad bytes at the end of a slab page */
  static int slab_pad_check(struct kmem_cache *s, struct page *page)
  {
  	u8 *start;
  	u8 *fault;
  	u8 *end;
  	u8 *pad;
  	int length;
  	int remainder;
  
  	if (!(s->flags & SLAB_POISON))
  		return 1;
  
  	start = page_address(page);
  	length = (PAGE_SIZE << compound_order(page)) - s->reserved;
  	end = start + length;
  	remainder = length % s->size;
  	if (!remainder)
  		return 1;
  
  	pad = end - remainder;
  	metadata_access_enable();
  	fault = memchr_inv(pad, POISON_INUSE, remainder);
  	metadata_access_disable();
  	if (!fault)
  		return 1;
  	while (end > fault && end[-1] == POISON_INUSE)
  		end--;
  
  	slab_err(s, page, "Padding overwritten. 0x%p-0x%p", fault, end - 1);
  	print_section(KERN_ERR, "Padding ", pad, remainder);
  
  	restore_bytes(s, "slab padding", POISON_INUSE, fault, end);
  	return 0;
  }
  
  static int check_object(struct kmem_cache *s, struct page *page,
  					void *object, u8 val)
  {
  	u8 *p = object;
  	u8 *endobject = object + s->object_size;
  
  	if (s->flags & SLAB_RED_ZONE) {
  		if (!check_bytes_and_report(s, page, object, "Redzone",
  			object - s->red_left_pad, val, s->red_left_pad))
  			return 0;
  
  		if (!check_bytes_and_report(s, page, object, "Redzone",
  			endobject, val, s->inuse - s->object_size))
  			return 0;
  	} else {
  		if ((s->flags & SLAB_POISON) && s->object_size < s->inuse) {
  			check_bytes_and_report(s, page, p, "Alignment padding",
  				endobject, POISON_INUSE,
  				s->inuse - s->object_size);
  		}
  	}
  
  	if (s->flags & SLAB_POISON) {
  		if (val != SLUB_RED_ACTIVE && (s->flags & __OBJECT_POISON) &&
  			(!check_bytes_and_report(s, page, p, "Poison", p,
  					POISON_FREE, s->object_size - 1) ||
  			 !check_bytes_and_report(s, page, p, "Poison",
  				p + s->object_size - 1, POISON_END, 1)))
  			return 0;
  		/*
  		 * check_pad_bytes cleans up on its own.
  		 */
  		check_pad_bytes(s, page, p);
  	}
  
  	if (!s->offset && val == SLUB_RED_ACTIVE)
  		/*
  		 * Object and freepointer overlap. Cannot check
  		 * freepointer while object is allocated.
  		 */
  		return 1;
  
  	/* Check free pointer validity */
  	if (!check_valid_pointer(s, page, get_freepointer(s, p))) {
  		object_err(s, page, p, "Freepointer corrupt");
  		/*
  		 * No choice but to zap it and thus lose the remainder
  		 * of the free objects in this slab. May cause
  		 * another error because the object count is now wrong.
  		 */
  		set_freepointer(s, p, NULL);
  		return 0;
  	}
  	return 1;
  }
  
  static int check_slab(struct kmem_cache *s, struct page *page)
  {
  	int maxobj;
  
  	VM_BUG_ON(!irqs_disabled());
  
  	if (!PageSlab(page)) {
  		slab_err(s, page, "Not a valid slab page");
  		return 0;
  	}
  
  	maxobj = order_objects(compound_order(page), s->size, s->reserved);
  	if (page->objects > maxobj) {
  		slab_err(s, page, "objects %u > max %u",
  			page->objects, maxobj);
  		return 0;
  	}
  	if (page->inuse > page->objects) {
  		slab_err(s, page, "inuse %u > max %u",
  			page->inuse, page->objects);
  		return 0;
  	}
  	/* Slab_pad_check fixes things up after itself */
  	slab_pad_check(s, page);
  	return 1;
  }
  
  /*
   * Determine if a certain object on a page is on the freelist. Must hold the
   * slab lock to guarantee that the chains are in a consistent state.
   */
  static int on_freelist(struct kmem_cache *s, struct page *page, void *search)
  {
  	int nr = 0;
  	void *fp;
  	void *object = NULL;
  	int max_objects;
  
  	fp = page->freelist;
  	while (fp && nr <= page->objects) {
  		if (fp == search)
  			return 1;
  		if (!check_valid_pointer(s, page, fp)) {
  			if (object) {
  				object_err(s, page, object,
  					"Freechain corrupt");
  				set_freepointer(s, object, NULL);
  			} else {
  				slab_err(s, page, "Freepointer corrupt");
  				page->freelist = NULL;
  				page->inuse = page->objects;
  				slab_fix(s, "Freelist cleared");
  				return 0;
  			}
  			break;
  		}
  		object = fp;
  		fp = get_freepointer(s, object);
  		nr++;
  	}
  
  	max_objects = order_objects(compound_order(page), s->size, s->reserved);
  	if (max_objects > MAX_OBJS_PER_PAGE)
  		max_objects = MAX_OBJS_PER_PAGE;
  
  	if (page->objects != max_objects) {
  		slab_err(s, page, "Wrong number of objects. Found %d but should be %d",
  			 page->objects, max_objects);
  		page->objects = max_objects;
  		slab_fix(s, "Number of objects adjusted.");
  	}
  	if (page->inuse != page->objects - nr) {
  		slab_err(s, page, "Wrong object count. Counter is %d but counted were %d",
  			 page->inuse, page->objects - nr);
  		page->inuse = page->objects - nr;
  		slab_fix(s, "Object count adjusted.");
  	}
  	return search == NULL;
  }
  
  static void trace(struct kmem_cache *s, struct page *page, void *object,
  								int alloc)
  {
  	if (s->flags & SLAB_TRACE) {
  		pr_info("TRACE %s %s 0x%p inuse=%d fp=0x%p\n",
  			s->name,
  			alloc ? "alloc" : "free",
  			object, page->inuse,
  			page->freelist);
  
  		if (!alloc)
  			print_section(KERN_INFO, "Object ", (void *)object,
  					s->object_size);
  
  		dump_stack();
  	}
  }
  
  /*
   * Tracking of fully allocated slabs for debugging purposes.
   */
  static void add_full(struct kmem_cache *s,
  	struct kmem_cache_node *n, struct page *page)
  {
  	if (!(s->flags & SLAB_STORE_USER))
  		return;
  
  	lockdep_assert_held(&n->list_lock);
  	list_add(&page->lru, &n->full);
  }
  
  static void remove_full(struct kmem_cache *s, struct kmem_cache_node *n, struct page *page)
  {
  	if (!(s->flags & SLAB_STORE_USER))
  		return;
  
  	lockdep_assert_held(&n->list_lock);
  	list_del(&page->lru);
  }
  
  /* Tracking of the number of slabs for debugging purposes */
  static inline unsigned long slabs_node(struct kmem_cache *s, int node)
  {
  	struct kmem_cache_node *n = get_node(s, node);
  
  	return atomic_long_read(&n->nr_slabs);
  }
  
  static inline unsigned long node_nr_slabs(struct kmem_cache_node *n)
  {
  	return atomic_long_read(&n->nr_slabs);
  }
  
  static inline void inc_slabs_node(struct kmem_cache *s, int node, int objects)
  {
  	struct kmem_cache_node *n = get_node(s, node);
  
  	/*
  	 * May be called early in order to allocate a slab for the
  	 * kmem_cache_node structure. Solve the chicken-egg
  	 * dilemma by deferring the increment of the count during
  	 * bootstrap (see early_kmem_cache_node_alloc).
  	 */
  	if (likely(n)) {
  		atomic_long_inc(&n->nr_slabs);
  		atomic_long_add(objects, &n->total_objects);
  	}
  }
  static inline void dec_slabs_node(struct kmem_cache *s, int node, int objects)
  {
  	struct kmem_cache_node *n = get_node(s, node);
  
  	atomic_long_dec(&n->nr_slabs);
  	atomic_long_sub(objects, &n->total_objects);
  }
  
  /* Object debug checks for alloc/free paths */
  static void setup_object_debug(struct kmem_cache *s, struct page *page,
  								void *object)
  {
  	if (!(s->flags & (SLAB_STORE_USER|SLAB_RED_ZONE|__OBJECT_POISON)))
  		return;
  
  	init_object(s, object, SLUB_RED_INACTIVE);
  	init_tracking(s, object);
  }
  
  static inline int alloc_consistency_checks(struct kmem_cache *s,
  					struct page *page,
  					void *object, unsigned long addr)
  {
  	if (!check_slab(s, page))
  		return 0;
  
  	if (!check_valid_pointer(s, page, object)) {
  		object_err(s, page, object, "Freelist Pointer check fails");
  		return 0;
  	}
  
  	if (!check_object(s, page, object, SLUB_RED_INACTIVE))
  		return 0;
  
  	return 1;
  }
  
  static noinline int alloc_debug_processing(struct kmem_cache *s,
  					struct page *page,
  					void *object, unsigned long addr)
  {
  	if (s->flags & SLAB_CONSISTENCY_CHECKS) {
  		if (!alloc_consistency_checks(s, page, object, addr))
  			goto bad;
  	}
  
  	/* Success perform special debug activities for allocs */
  	if (s->flags & SLAB_STORE_USER)
  		set_track(s, object, TRACK_ALLOC, addr);
  	trace(s, page, object, 1);
  	init_object(s, object, SLUB_RED_ACTIVE);
  	return 1;
  
  bad:
  	if (PageSlab(page)) {
  		/*
  		 * If this is a slab page then lets do the best we can
  		 * to avoid issues in the future. Marking all objects
  		 * as used avoids touching the remaining objects.
  		 */
  		slab_fix(s, "Marking all objects used");
  		page->inuse = page->objects;
  		page->freelist = NULL;
  	}
  	return 0;
  }
  
  static inline int free_consistency_checks(struct kmem_cache *s,
  		struct page *page, void *object, unsigned long addr)
  {
  	if (!check_valid_pointer(s, page, object)) {
  		slab_err(s, page, "Invalid object pointer 0x%p", object);
  		return 0;
  	}
  
  	if (on_freelist(s, page, object)) {
  		object_err(s, page, object, "Object already free");
  		return 0;
  	}
  
  	if (!check_object(s, page, object, SLUB_RED_ACTIVE))
  		return 0;
  
  	if (unlikely(s != page->slab_cache)) {
  		if (!PageSlab(page)) {
  			slab_err(s, page, "Attempt to free object(0x%p) outside of slab",
  				 object);
  		} else if (!page->slab_cache) {
  			pr_err("SLUB <none>: no slab for object 0x%p.\n",
  			       object);
  			dump_stack();
  		} else
  			object_err(s, page, object,
  					"page slab pointer corrupt.");
  		return 0;
  	}
  	return 1;
  }
  
  /* Supports checking bulk free of a constructed freelist */
  static noinline int free_debug_processing(
  	struct kmem_cache *s, struct page *page,
  	void *head, void *tail, int bulk_cnt,
  	unsigned long addr)
  {
  	struct kmem_cache_node *n = get_node(s, page_to_nid(page));
  	void *object = head;
  	int cnt = 0;
  	unsigned long uninitialized_var(flags);
  	int ret = 0;
  
  	spin_lock_irqsave(&n->list_lock, flags);
  	slab_lock(page);
  
  	if (s->flags & SLAB_CONSISTENCY_CHECKS) {
  		if (!check_slab(s, page))
  			goto out;
  	}
  
  next_object:
  	cnt++;
  
  	if (s->flags & SLAB_CONSISTENCY_CHECKS) {
  		if (!free_consistency_checks(s, page, object, addr))
  			goto out;
  	}
  
  	if (s->flags & SLAB_STORE_USER)
  		set_track(s, object, TRACK_FREE, addr);
  	trace(s, page, object, 0);
  	/* Freepointer not overwritten by init_object(), SLAB_POISON moved it */
  	init_object(s, object, SLUB_RED_INACTIVE);
  
  	/* Reached end of constructed freelist yet? */
  	if (object != tail) {
  		object = get_freepointer(s, object);
  		goto next_object;
  	}
  	ret = 1;
  
  out:
  	if (cnt != bulk_cnt)
  		slab_err(s, page, "Bulk freelist count(%d) invalid(%d)\n",
  			 bulk_cnt, cnt);
  
  	slab_unlock(page);
  	spin_unlock_irqrestore(&n->list_lock, flags);
  	if (!ret)
  		slab_fix(s, "Object at 0x%p not freed", object);
  	return ret;
  }
  
  static int __init setup_slub_debug(char *str)
  {
  	slub_debug = DEBUG_DEFAULT_FLAGS;
  	if (*str++ != '=' || !*str)
  		/*
  		 * No options specified. Switch on full debugging.
  		 */
  		goto out;
  
  	if (*str == ',')
  		/*
  		 * No options but restriction on slabs. This means full
  		 * debugging for slabs matching a pattern.
  		 */
  		goto check_slabs;
  
  	slub_debug = 0;
  	if (*str == '-')
  		/*
  		 * Switch off all debugging measures.
  		 */
  		goto out;
  
  	/*
  	 * Determine which debug features should be switched on
  	 */
  	for (; *str && *str != ','; str++) {
  		switch (tolower(*str)) {
  		case 'f':
  			slub_debug |= SLAB_CONSISTENCY_CHECKS;
  			break;
  		case 'z':
  			slub_debug |= SLAB_RED_ZONE;
  			break;
  		case 'p':
  			slub_debug |= SLAB_POISON;
  			break;
  		case 'u':
  			slub_debug |= SLAB_STORE_USER;
  			break;
  		case 't':
  			slub_debug |= SLAB_TRACE;
  			break;
  		case 'a':
  			slub_debug |= SLAB_FAILSLAB;
  			break;
  		case 'o':
  			/*
  			 * Avoid enabling debugging on caches if its minimum
  			 * order would increase as a result.
  			 */
  			disable_higher_order_debug = 1;
  			break;
  		default:
  			pr_err("slub_debug option '%c' unknown. skipped\n",
  			       *str);
  		}
  	}
  
  check_slabs:
  	if (*str == ',')
  		slub_debug_slabs = str + 1;
  out:
  	return 1;
  }
  
  __setup("slub_debug", setup_slub_debug);
  
  slab_flags_t kmem_cache_flags(unsigned int object_size,
  	slab_flags_t flags, const char *name,
  	void (*ctor)(void *))
  {
  	/*
  	 * Enable debugging if selected on the kernel commandline.
  	 */
  	if (slub_debug && (!slub_debug_slabs || (name &&
  		!strncmp(slub_debug_slabs, name, strlen(slub_debug_slabs)))))
  		flags |= slub_debug;
  
  	return flags;
  }
  #else /* !CONFIG_SLUB_DEBUG */
  static inline void setup_object_debug(struct kmem_cache *s,
  			struct page *page, void *object) {}
  
  static inline int alloc_debug_processing(struct kmem_cache *s,
  	struct page *page, void *object, unsigned long addr) { return 0; }
  
  static inline int free_debug_processing(
  	struct kmem_cache *s, struct page *page,
  	void *head, void *tail, int bulk_cnt,
  	unsigned long addr) { return 0; }
  
  static inline int slab_pad_check(struct kmem_cache *s, struct page *page)
  			{ return 1; }
  static inline int check_object(struct kmem_cache *s, struct page *page,
  			void *object, u8 val) { return 1; }
  static inline void add_full(struct kmem_cache *s, struct kmem_cache_node *n,
  					struct page *page) {}
  static inline void remove_full(struct kmem_cache *s, struct kmem_cache_node *n,
  					struct page *page) {}
  slab_flags_t kmem_cache_flags(unsigned int object_size,
  	slab_flags_t flags, const char *name,
  	void (*ctor)(void *))
  {
  	return flags;
  }
  #define slub_debug 0
  
  #define disable_higher_order_debug 0
  
  static inline unsigned long slabs_node(struct kmem_cache *s, int node)
  							{ return 0; }
  static inline unsigned long node_nr_slabs(struct kmem_cache_node *n)
  							{ return 0; }
  static inline void inc_slabs_node(struct kmem_cache *s, int node,
  							int objects) {}
  static inline void dec_slabs_node(struct kmem_cache *s, int node,
  							int objects) {}
  
  #endif /* CONFIG_SLUB_DEBUG */
  
  /*
   * Hooks for other subsystems that check memory allocations. In a typical
   * production configuration these hooks all should produce no code at all.
   */
  static inline void kmalloc_large_node_hook(void *ptr, size_t size, gfp_t flags)
  {
  	kmemleak_alloc(ptr, size, 1, flags);
  	kasan_kmalloc_large(ptr, size, flags);
  }
  
  static __always_inline void kfree_hook(void *x)
  {
  	kmemleak_free(x);
  	kasan_kfree_large(x, _RET_IP_);
  }
  
  static __always_inline bool slab_free_hook(struct kmem_cache *s, void *x)
  {
  	kmemleak_free_recursive(x, s->flags);
  
  	/*
  	 * Trouble is that we may no longer disable interrupts in the fast path
  	 * So in order to make the debug calls that expect irqs to be
  	 * disabled we need to disable interrupts temporarily.
  	 */
  #ifdef CONFIG_LOCKDEP
  	{
  		unsigned long flags;
  
  		local_irq_save(flags);
  		debug_check_no_locks_freed(x, s->object_size);
  		local_irq_restore(flags);
  	}
  #endif
  	if (!(s->flags & SLAB_DEBUG_OBJECTS))
  		debug_check_no_obj_freed(x, s->object_size);
  
  	/* KASAN might put x into memory quarantine, delaying its reuse */
  	return kasan_slab_free(s, x, _RET_IP_);
  }
  
  static inline bool slab_free_freelist_hook(struct kmem_cache *s,
  					   void **head, void **tail)
  {
  /*
   * Compiler cannot detect this function can be removed if slab_free_hook()
   * evaluates to nothing.  Thus, catch all relevant config debug options here.
   */
  #if defined(CONFIG_LOCKDEP)	||		\
  	defined(CONFIG_DEBUG_KMEMLEAK) ||	\
  	defined(CONFIG_DEBUG_OBJECTS_FREE) ||	\
  	defined(CONFIG_KASAN)
  
  	void *object;
  	void *next = *head;
  	void *old_tail = *tail ? *tail : *head;
  
  	/* Head and tail of the reconstructed freelist */
  	*head = NULL;
  	*tail = NULL;
  
  	do {
  		object = next;
  		next = get_freepointer(s, object);
  		/* If object's reuse doesn't have to be delayed */
  		if (!slab_free_hook(s, object)) {
  			/* Move object to the new freelist */
  			set_freepointer(s, object, *head);
  			*head = object;
  			if (!*tail)
  				*tail = object;
  		}
  	} while (object != old_tail);
  
  	if (*head == *tail)
  		*tail = NULL;
  
  	return *head != NULL;
  #else
  	return true;
  #endif
  }
  
  static void setup_object(struct kmem_cache *s, struct page *page,
  				void *object)
  {
  	setup_object_debug(s, page, object);
  	kasan_init_slab_obj(s, object);
  	if (unlikely(s->ctor)) {
  		kasan_unpoison_object_data(s, object);
  		s->ctor(object);
  		kasan_poison_object_data(s, object);
  	}
  }
  
  /*
   * Slab allocation and freeing
   */
  static inline struct page *alloc_slab_page(struct kmem_cache *s,
  		gfp_t flags, int node, struct kmem_cache_order_objects oo)
  {
  	struct page *page;
  	unsigned int order = oo_order(oo);
  
  	if (node == NUMA_NO_NODE)
  		page = alloc_pages(flags, order);
  	else
  		page = __alloc_pages_node(node, flags, order);
  
  	if (page && memcg_charge_slab(page, flags, order, s)) {
  		__free_pages(page, order);
  		page = NULL;
  	}
  
  	return page;
  }
  
  #ifdef CONFIG_SLAB_FREELIST_RANDOM
  /* Pre-initialize the random sequence cache */
  static int init_cache_random_seq(struct kmem_cache *s)
  {
  	unsigned int count = oo_objects(s->oo);
  	int err;
  
  	/* Bailout if already initialised */
  	if (s->random_seq)
  		return 0;
  
  	err = cache_random_seq_create(s, count, GFP_KERNEL);
  	if (err) {
  		pr_err("SLUB: Unable to initialize free list for %s\n",
  			s->name);
  		return err;
  	}
  
  	/* Transform to an offset on the set of pages */
  	if (s->random_seq) {
  		unsigned int i;
  
  		for (i = 0; i < count; i++)
  			s->random_seq[i] *= s->size;
  	}
  	return 0;
  }
  
  /* Initialize each random sequence freelist per cache */
  static void __init init_freelist_randomization(void)
  {
  	struct kmem_cache *s;
  
  	mutex_lock(&slab_mutex);
  
  	list_for_each_entry(s, &slab_caches, list)
  		init_cache_random_seq(s);
  
  	mutex_unlock(&slab_mutex);
  }
  
  /* Get the next entry on the pre-computed freelist randomized */
  static void *next_freelist_entry(struct kmem_cache *s, struct page *page,
  				unsigned long *pos, void *start,
  				unsigned long page_limit,
  				unsigned long freelist_count)
  {
  	unsigned int idx;
  
  	/*
  	 * If the target page allocation failed, the number of objects on the
  	 * page might be smaller than the usual size defined by the cache.
  	 */
  	do {
  		idx = s->random_seq[*pos];
  		*pos += 1;
  		if (*pos >= freelist_count)
  			*pos = 0;
  	} while (unlikely(idx >= page_limit));
  
  	return (char *)start + idx;
  }
  
  /* Shuffle the single linked freelist based on a random pre-computed sequence */
  static bool shuffle_freelist(struct kmem_cache *s, struct page *page)
  {
  	void *start;
  	void *cur;
  	void *next;
  	unsigned long idx, pos, page_limit, freelist_count;
  
  	if (page->objects < 2 || !s->random_seq)
  		return false;
  
  	freelist_count = oo_objects(s->oo);
  	pos = get_random_int() % freelist_count;
  
  	page_limit = page->objects * s->size;
  	start = fixup_red_left(s, page_address(page));
  
  	/* First entry is used as the base of the freelist */
  	cur = next_freelist_entry(s, page, &pos, start, page_limit,
  				freelist_count);
  	page->freelist = cur;
  
  	for (idx = 1; idx < page->objects; idx++) {
  		setup_object(s, page, cur);
  		next = next_freelist_entry(s, page, &pos, start, page_limit,
  			freelist_count);
  		set_freepointer(s, cur, next);
  		cur = next;
  	}
  	setup_object(s, page, cur);
  	set_freepointer(s, cur, NULL);
  
  	return true;
  }
  #else
  static inline int init_cache_random_seq(struct kmem_cache *s)
  {
  	return 0;
  }
  static inline void init_freelist_randomization(void) { }
  static inline bool shuffle_freelist(struct kmem_cache *s, struct page *page)
  {
  	return false;
  }
  #endif /* CONFIG_SLAB_FREELIST_RANDOM */
  
  static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
  {
  	struct page *page;
  	struct kmem_cache_order_objects oo = s->oo;
  	gfp_t alloc_gfp;
  	void *start, *p;
  	int idx, order;
  	bool shuffle;
  
  	flags &= gfp_allowed_mask;
  
  	if (gfpflags_allow_blocking(flags))
  		local_irq_enable();
  
  	flags |= s->allocflags;
  
  	/*
  	 * Let the initial higher-order allocation fail under memory pressure
  	 * so we fall-back to the minimum order allocation.
  	 */
  	alloc_gfp = (flags | __GFP_NOWARN | __GFP_NORETRY) & ~__GFP_NOFAIL;
  	if ((alloc_gfp & __GFP_DIRECT_RECLAIM) && oo_order(oo) > oo_order(s->min))
  		alloc_gfp = (alloc_gfp | __GFP_NOMEMALLOC) & ~(__GFP_RECLAIM|__GFP_NOFAIL);
  
  	page = alloc_slab_page(s, alloc_gfp, node, oo);
  	if (unlikely(!page)) {
  		oo = s->min;
  		alloc_gfp = flags;
  		/*
  		 * Allocation may have failed due to fragmentation.
  		 * Try a lower order alloc if possible
  		 */
  		page = alloc_slab_page(s, alloc_gfp, node, oo);
  		if (unlikely(!page))
  			goto out;
  		stat(s, ORDER_FALLBACK);
  	}
  
  	page->objects = oo_objects(oo);
  
  	order = compound_order(page);
  	page->slab_cache = s;
  	__SetPageSlab(page);
  	if (page_is_pfmemalloc(page))
  		SetPageSlabPfmemalloc(page);
  
  	start = page_address(page);
  
  	if (unlikely(s->flags & SLAB_POISON))
  		memset(start, POISON_INUSE, PAGE_SIZE << order);
  
  	kasan_poison_slab(page);
  
  	shuffle = shuffle_freelist(s, page);
  
  	if (!shuffle) {
  		for_each_object_idx(p, idx, s, start, page->objects) {
  			setup_object(s, page, p);
  			if (likely(idx < page->objects))
  				set_freepointer(s, p, p + s->size);
  			else
  				set_freepointer(s, p, NULL);
  		}
  		page->freelist = fixup_red_left(s, start);
  	}
  
  	page->inuse = page->objects;
  	page->frozen = 1;
  
  out:
  	if (gfpflags_allow_blocking(flags))
  		local_irq_disable();
  	if (!page)
  		return NULL;
  
  	mod_lruvec_page_state(page,
  		(s->flags & SLAB_RECLAIM_ACCOUNT) ?
  		NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
  		1 << oo_order(oo));
  
  	inc_slabs_node(s, page_to_nid(page), page->objects);
  
  	return page;
  }
  
  static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
  {
  	if (unlikely(flags & GFP_SLAB_BUG_MASK)) {
  		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 allocate_slab(s,
  		flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
  }
  
  static void __free_slab(struct kmem_cache *s, struct page *page)
  {
  	int order = compound_order(page);
  	int pages = 1 << order;
  
  	if (s->flags & SLAB_CONSISTENCY_CHECKS) {
  		void *p;
  
  		slab_pad_check(s, page);
  		for_each_object(p, s, page_address(page),
  						page->objects)
  			check_object(s, page, p, SLUB_RED_INACTIVE);
  	}
  
  	mod_lruvec_page_state(page,
  		(s->flags & SLAB_RECLAIM_ACCOUNT) ?
  		NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
  		-pages);
  
  	__ClearPageSlabPfmemalloc(page);
  	__ClearPageSlab(page);
  
  	page_mapcount_reset(page);
  	if (current->reclaim_state)
  		current->reclaim_state->reclaimed_slab += pages;
  	memcg_uncharge_slab(page, order, s);
  	__free_pages(page, order);
  }
  
  #define need_reserve_slab_rcu						\
  	(sizeof(((struct page *)NULL)->lru) < sizeof(struct rcu_head))
  
  static void rcu_free_slab(struct rcu_head *h)
  {
  	struct page *page;
  
  	if (need_reserve_slab_rcu)
  		page = virt_to_head_page(h);
  	else
  		page = container_of((struct list_head *)h, struct page, lru);
  
  	__free_slab(page->slab_cache, page);
  }
  
  static void free_slab(struct kmem_cache *s, struct page *page)
  {
  	if (unlikely(s->flags & SLAB_TYPESAFE_BY_RCU)) {
  		struct rcu_head *head;
  
  		if (need_reserve_slab_rcu) {
  			int order = compound_order(page);
  			int offset = (PAGE_SIZE << order) - s->reserved;
  
  			VM_BUG_ON(s->reserved != sizeof(*head));
  			head = page_address(page) + offset;
  		} else {
  			head = &page->rcu_head;
  		}
  
  		call_rcu(head, rcu_free_slab);
  	} else
  		__free_slab(s, page);
  }
  
  static void discard_slab(struct kmem_cache *s, struct page *page)
  {
  	dec_slabs_node(s, page_to_nid(page), page->objects);
  	free_slab(s, page);
  }
  
  /*
   * Management of partially allocated slabs.
   */
  static inline void
  __add_partial(struct kmem_cache_node *n, struct page *page, int tail)
  {
  	n->nr_partial++;
  	if (tail == DEACTIVATE_TO_TAIL)
  		list_add_tail(&page->lru, &n->partial);
  	else
  		list_add(&page->lru, &n->partial);
  }
  
  static inline void add_partial(struct kmem_cache_node *n,
  				struct page *page, int tail)
  {
  	lockdep_assert_held(&n->list_lock);
  	__add_partial(n, page, tail);
  }
  
  static inline void remove_partial(struct kmem_cache_node *n,
  					struct page *page)
  {
  	lockdep_assert_held(&n->list_lock);
  	list_del(&page->lru);
  	n->nr_partial--;
  }
  
  /*
   * Remove slab from the partial list, freeze it and
   * return the pointer to the freelist.
   *
   * Returns a list of objects or NULL if it fails.
   */
  static inline void *acquire_slab(struct kmem_cache *s,
  		struct kmem_cache_node *n, struct page *page,
  		int mode, int *objects)
  {
  	void *freelist;
  	unsigned long counters;
  	struct page new;
  
  	lockdep_assert_held(&n->list_lock);
  
  	/*
  	 * Zap the freelist and set the frozen bit.
  	 * The old freelist is the list of objects for the
  	 * per cpu allocation list.
  	 */
  	freelist = page->freelist;
  	counters = page->counters;
  	new.counters = counters;
  	*objects = new.objects - new.inuse;
  	if (mode) {
  		new.inuse = page->objects;
  		new.freelist = NULL;
  	} else {
  		new.freelist = freelist;
  	}
  
  	VM_BUG_ON(new.frozen);
  	new.frozen = 1;
  
  	if (!__cmpxchg_double_slab(s, page,
  			freelist, counters,
  			new.freelist, new.counters,
  			"acquire_slab"))
  		return NULL;
  
  	remove_partial(n, page);
  	WARN_ON(!freelist);
  	return freelist;
  }
  
  static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain);
  static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags);
  
  /*
   * Try to allocate a partial slab from a specific node.
   */
  static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n,
  				struct kmem_cache_cpu *c, gfp_t flags)
  {
  	struct page *page, *page2;
  	void *object = NULL;
  	unsigned int available = 0;
  	int objects;
  
  	/*
  	 * Racy check. If we mistakenly see no partial slabs then we
  	 * just allocate an empty slab. If we mistakenly try to get a
  	 * partial slab and there is none available then get_partials()
  	 * will return NULL.
  	 */
  	if (!n || !n->nr_partial)
  		return NULL;
  
  	spin_lock(&n->list_lock);
  	list_for_each_entry_safe(page, page2, &n->partial, lru) {
  		void *t;
  
  		if (!pfmemalloc_match(page, flags))
  			continue;
  
  		t = acquire_slab(s, n, page, object == NULL, &objects);
  		if (!t)
  			break;
  
  		available += objects;
  		if (!object) {
  			c->page = page;
  			stat(s, ALLOC_FROM_PARTIAL);
  			object = t;
  		} else {
  			put_cpu_partial(s, page, 0);
  			stat(s, CPU_PARTIAL_NODE);
  		}
  		if (!kmem_cache_has_cpu_partial(s)
  			|| available > slub_cpu_partial(s) / 2)
  			break;
  
  	}
  	spin_unlock(&n->list_lock);
  	return object;
  }
  
  /*
   * Get a page from somewhere. Search in increasing NUMA distances.
   */
  static void *get_any_partial(struct kmem_cache *s, gfp_t flags,
  		struct kmem_cache_cpu *c)
  {
  #ifdef CONFIG_NUMA
  	struct zonelist *zonelist;
  	struct zoneref *z;
  	struct zone *zone;
  	enum zone_type high_zoneidx = gfp_zone(flags);
  	void *object;
  	unsigned int cpuset_mems_cookie;
  
  	/*
  	 * The defrag ratio allows a configuration of the tradeoffs between
  	 * inter node defragmentation and node local allocations. A lower
  	 * defrag_ratio increases the tendency to do local allocations
  	 * instead of attempting to obtain partial slabs from other nodes.
  	 *
  	 * If the defrag_ratio is set to 0 then kmalloc() always
  	 * returns node local objects. If the ratio is higher then kmalloc()
  	 * may return off node objects because partial slabs are obtained
  	 * from other nodes and filled up.
  	 *
  	 * If /sys/kernel/slab/xx/remote_node_defrag_ratio is set to 100
  	 * (which makes defrag_ratio = 1000) then every (well almost)
  	 * allocation will first attempt to defrag slab caches on other nodes.
  	 * This means scanning over all nodes to look for partial slabs which
  	 * may be expensive if we do it every time we are trying to find a slab
  	 * with available objects.
  	 */
  	if (!s->remote_node_defrag_ratio ||
  			get_cycles() % 1024 > s->remote_node_defrag_ratio)
  		return NULL;
  
  	do {
  		cpuset_mems_cookie = read_mems_allowed_begin();
  		zonelist = node_zonelist(mempolicy_slab_node(), flags);
  		for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
  			struct kmem_cache_node *n;
  
  			n = get_node(s, zone_to_nid(zone));
  
  			if (n && cpuset_zone_allowed(zone, flags) &&
  					n->nr_partial > s->min_partial) {
  				object = get_partial_node(s, n, c, flags);
  				if (object) {
  					/*
  					 * Don't check read_mems_allowed_retry()
  					 * here - if mems_allowed was updated in
  					 * parallel, that was a harmless race
  					 * between allocation and the cpuset
  					 * update
  					 */
  					return object;
  				}
  			}
  		}
  	} while (read_mems_allowed_retry(cpuset_mems_cookie));
  #endif
  	return NULL;
  }
  
  /*
   * Get a partial page, lock it and return it.
   */
  static void *get_partial(struct kmem_cache *s, gfp_t flags, int node,
  		struct kmem_cache_cpu *c)
  {
  	void *object;
  	int searchnode = node;
  
  	if (node == NUMA_NO_NODE)
  		searchnode = numa_mem_id();
  	else if (!node_present_pages(node))
  		searchnode = node_to_mem_node(node);
  
  	object = get_partial_node(s, get_node(s, searchnode), c, flags);
  	if (object || node != NUMA_NO_NODE)
  		return object;
  
  	return get_any_partial(s, flags, c);
  }
  
  #ifdef CONFIG_PREEMPT
  /*
   * Calculate the next globally unique transaction for disambiguiation
   * during cmpxchg. The transactions start with the cpu number and are then
   * incremented by CONFIG_NR_CPUS.
   */
  #define TID_STEP  roundup_pow_of_two(CONFIG_NR_CPUS)
  #else
  /*
   * No preemption supported therefore also no need to check for
   * different cpus.
   */
  #define TID_STEP 1
  #endif
  
  static inline unsigned long next_tid(unsigned long tid)
  {
  	return tid + TID_STEP;
  }
  
  static inline unsigned int tid_to_cpu(unsigned long tid)
  {
  	return tid % TID_STEP;
  }
  
  static inline unsigned long tid_to_event(unsigned long tid)
  {
  	return tid / TID_STEP;
  }
  
  static inline unsigned int init_tid(int cpu)
  {
  	return cpu;
  }
  
  static inline void note_cmpxchg_failure(const char *n,
  		const struct kmem_cache *s, unsigned long tid)
  {
  #ifdef SLUB_DEBUG_CMPXCHG
  	unsigned long actual_tid = __this_cpu_read(s->cpu_slab->tid);
  
  	pr_info("%s %s: cmpxchg redo ", n, s->name);
  
  #ifdef CONFIG_PREEMPT
  	if (tid_to_cpu(tid) != tid_to_cpu(actual_tid))
  		pr_warn("due to cpu change %d -> %d\n",
  			tid_to_cpu(tid), tid_to_cpu(actual_tid));
  	else
  #endif
  	if (tid_to_event(tid) != tid_to_event(actual_tid))
  		pr_warn("due to cpu running other code. Event %ld->%ld\n",
  			tid_to_event(tid), tid_to_event(actual_tid));
  	else
  		pr_warn("for unknown reason: actual=%lx was=%lx target=%lx\n",
  			actual_tid, tid, next_tid(tid));
  #endif
  	stat(s, CMPXCHG_DOUBLE_CPU_FAIL);
  }
  
  static void init_kmem_cache_cpus(struct kmem_cache *s)
  {
  	int cpu;
  
  	for_each_possible_cpu(cpu)
  		per_cpu_ptr(s->cpu_slab, cpu)->tid = init_tid(cpu);
  }
  
  /*
   * Remove the cpu slab
   */
  static void deactivate_slab(struct kmem_cache *s, struct page *page,
  				void *freelist, struct kmem_cache_cpu *c)
  {
  	enum slab_modes { M_NONE, M_PARTIAL, M_FULL, M_FREE };
  	struct kmem_cache_node *n = get_node(s, page_to_nid(page));
  	int lock = 0;
  	enum slab_modes l = M_NONE, m = M_NONE;
  	void *nextfree;
  	int tail = DEACTIVATE_TO_HEAD;
  	struct page new;
  	struct page old;
  
  	if (page->freelist) {
  		stat(s, DEACTIVATE_REMOTE_FREES);
  		tail = DEACTIVATE_TO_TAIL;
  	}
  
  	/*
  	 * Stage one: Free all available per cpu objects back
  	 * to the page freelist while it is still frozen. Leave the
  	 * last one.
  	 *
  	 * There is no need to take the list->lock because the page
  	 * is still frozen.
  	 */
  	while (freelist && (nextfree = get_freepointer(s, freelist))) {
  		void *prior;
  		unsigned long counters;
  
  		do {
  			prior = page->freelist;
  			counters = page->counters;
  			set_freepointer(s, freelist, prior);
  			new.counters = counters;
  			new.inuse--;
  			VM_BUG_ON(!new.frozen);
  
  		} while (!__cmpxchg_double_slab(s, page,
  			prior, counters,
  			freelist, new.counters,
  			"drain percpu freelist"));
  
  		freelist = nextfree;
  	}
  
  	/*
  	 * Stage two: Ensure that the page is unfrozen while the
  	 * list presence reflects the actual number of objects
  	 * during unfreeze.
  	 *
  	 * We setup the list membership and then perform a cmpxchg
  	 * with the count. If there is a mismatch then the page
  	 * is not unfrozen but the page is on the wrong list.
  	 *
  	 * Then we restart the process which may have to remove
  	 * the page from the list that we just put it on again
  	 * because the number of objects in the slab may have
  	 * changed.
  	 */
  redo:
  
  	old.freelist = page->freelist;
  	old.counters = page->counters;
  	VM_BUG_ON(!old.frozen);
  
  	/* Determine target state of the slab */
  	new.counters = old.counters;
  	if (freelist) {
  		new.inuse--;
  		set_freepointer(s, freelist, old.freelist);
  		new.freelist = freelist;
  	} else
  		new.freelist = old.freelist;
  
  	new.frozen = 0;
  
  	if (!new.inuse && n->nr_partial >= s->min_partial)
  		m = M_FREE;
  	else if (new.freelist) {
  		m = M_PARTIAL;
  		if (!lock) {
  			lock = 1;
  			/*
  			 * Taking the spinlock removes the possiblity
  			 * that acquire_slab() will see a slab page that
  			 * is frozen
  			 */
  			spin_lock(&n->list_lock);
  		}
  	} else {
  		m = M_FULL;
  		if (kmem_cache_debug(s) && !lock) {
  			lock = 1;
  			/*
  			 * This also ensures that the scanning of full
  			 * slabs from diagnostic functions will not see
  			 * any frozen slabs.
  			 */
  			spin_lock(&n->list_lock);
  		}
  	}
  
  	if (l != m) {
  
  		if (l == M_PARTIAL)
  
  			remove_partial(n, page);
  
  		else if (l == M_FULL)
  
  			remove_full(s, n, page);
  
  		if (m == M_PARTIAL) {
  
  			add_partial(n, page, tail);
  			stat(s, tail);
  
  		} else if (m == M_FULL) {
  
  			stat(s, DEACTIVATE_FULL);
  			add_full(s, n, page);
  
  		}
  	}
  
  	l = m;
  	if (!__cmpxchg_double_slab(s, page,
  				old.freelist, old.counters,
  				new.freelist, new.counters,
  				"unfreezing slab"))
  		goto redo;
  
  	if (lock)
  		spin_unlock(&n->list_lock);
  
  	if (m == M_FREE) {
  		stat(s, DEACTIVATE_EMPTY);
  		discard_slab(s, page);
  		stat(s, FREE_SLAB);
  	}
  
  	c->page = NULL;
  	c->freelist = NULL;
  }
  
  /*
   * Unfreeze all the cpu partial slabs.
   *
   * This function must be called with interrupts disabled
   * for the cpu using c (or some other guarantee must be there
   * to guarantee no concurrent accesses).
   */
  static void unfreeze_partials(struct kmem_cache *s,
  		struct kmem_cache_cpu *c)
  {
  #ifdef CONFIG_SLUB_CPU_PARTIAL
  	struct kmem_cache_node *n = NULL, *n2 = NULL;
  	struct page *page, *discard_page = NULL;
  
  	while ((page = c->partial)) {
  		struct page new;
  		struct page old;
  
  		c->partial = page->next;
  
  		n2 = get_node(s, page_to_nid(page));
  		if (n != n2) {
  			if (n)
  				spin_unlock(&n->list_lock);
  
  			n = n2;
  			spin_lock(&n->list_lock);
  		}
  
  		do {
  
  			old.freelist = page->freelist;
  			old.counters = page->counters;
  			VM_BUG_ON(!old.frozen);
  
  			new.counters = old.counters;
  			new.freelist = old.freelist;
  
  			new.frozen = 0;
  
  		} while (!__cmpxchg_double_slab(s, page,
  				old.freelist, old.counters,
  				new.freelist, new.counters,
  				"unfreezing slab"));
  
  		if (unlikely(!new.inuse && n->nr_partial >= s->min_partial)) {
  			page->next = discard_page;
  			discard_page = page;
  		} else {
  			add_partial(n, page, DEACTIVATE_TO_TAIL);
  			stat(s, FREE_ADD_PARTIAL);
  		}
  	}
  
  	if (n)
  		spin_unlock(&n->list_lock);
  
  	while (discard_page) {
  		page = discard_page;
  		discard_page = discard_page->next;
  
  		stat(s, DEACTIVATE_EMPTY);
  		discard_slab(s, page);
  		stat(s, FREE_SLAB);
  	}
  #endif
  }
  
  /*
   * Put a page that was just frozen (in __slab_free) into a partial page
   * slot if available.
   *
   * If we did not find a slot then simply move all the partials to the
   * per node partial list.
   */
  static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain)
  {
  #ifdef CONFIG_SLUB_CPU_PARTIAL
  	struct page *oldpage;
  	int pages;
  	int pobjects;
  
  	preempt_disable();
  	do {
  		pages = 0;
  		pobjects = 0;
  		oldpage = this_cpu_read(s->cpu_slab->partial);
  
  		if (oldpage) {
  			pobjects = oldpage->pobjects;
  			pages = oldpage->pages;
  			if (drain && pobjects > s->cpu_partial) {
  				unsigned long flags;
  				/*
  				 * partial array is full. Move the existing
  				 * set to the per node partial list.
  				 */
  				local_irq_save(flags);
  				unfreeze_partials(s, this_cpu_ptr(s->cpu_slab));
  				local_irq_restore(flags);
  				oldpage = NULL;
  				pobjects = 0;
  				pages = 0;
  				stat(s, CPU_PARTIAL_DRAIN);
  			}
  		}
  
  		pages++;
  		pobjects += page->objects - page->inuse;
  
  		page->pages = pages;
  		page->pobjects = pobjects;
  		page->next = oldpage;
  
  	} while (this_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page)
  								!= oldpage);
  	if (unlikely(!s->cpu_partial)) {
  		unsigned long flags;
  
  		local_irq_save(flags);
  		unfreeze_partials(s, this_cpu_ptr(s->cpu_slab));
  		local_irq_restore(flags);
  	}
  	preempt_enable();
  #endif
  }
  
  static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
  {
  	stat(s, CPUSLAB_FLUSH);
  	deactivate_slab(s, c->page, c->freelist, c);
  
  	c->tid = next_tid(c->tid);
  }
  
  /*
   * Flush cpu slab.
   *
   * Called from IPI handler with interrupts disabled.
   */
  static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu)
  {
  	struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
  
  	if (likely(c)) {
  		if (c->page)
  			flush_slab(s, c);
  
  		unfreeze_partials(s, c);
  	}
  }
  
  static void flush_cpu_slab(void *d)
  {
  	struct kmem_cache *s = d;
  
  	__flush_cpu_slab(s, smp_processor_id());
  }
  
  static bool has_cpu_slab(int cpu, void *info)
  {
  	struct kmem_cache *s = info;
  	struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
  
  	return c->page || slub_percpu_partial(c);
  }
  
  static void flush_all(struct kmem_cache *s)
  {
  	on_each_cpu_cond(has_cpu_slab, flush_cpu_slab, s, 1, GFP_ATOMIC);
  }
  
  /*
   * Use the cpu notifier to insure that the cpu slabs are flushed when
   * necessary.
   */
  static int slub_cpu_dead(unsigned int cpu)
  {
  	struct kmem_cache *s;
  	unsigned long flags;
  
  	mutex_lock(&slab_mutex);
  	list_for_each_entry(s, &slab_caches, list) {
  		local_irq_save(flags);
  		__flush_cpu_slab(s, cpu);
  		local_irq_restore(flags);
  	}
  	mutex_unlock(&slab_mutex);
  	return 0;
  }
  
  /*
   * Check if the objects in a per cpu structure fit numa
   * locality expectations.
   */
  static inline int node_match(struct page *page, int node)
  {
  #ifdef CONFIG_NUMA
  	if (!page || (node != NUMA_NO_NODE && page_to_nid(page) != node))
  		return 0;
  #endif
  	return 1;
  }
  
  #ifdef CONFIG_SLUB_DEBUG
  static int count_free(struct page *page)
  {
  	return page->objects - page->inuse;
  }
  
  static inline unsigned long node_nr_objs(struct kmem_cache_node *n)
  {
  	return atomic_long_read(&n->total_objects);
  }
  #endif /* CONFIG_SLUB_DEBUG */
  
  #if defined(CONFIG_SLUB_DEBUG) || defined(CONFIG_SYSFS)
  static unsigned long count_partial(struct kmem_cache_node *n,
  					int (*get_count)(struct page *))
  {
  	unsigned long flags;
  	unsigned long x = 0;
  	struct page *page;
  
  	spin_lock_irqsave(&n->list_lock, flags);
  	list_for_each_entry(page, &n->partial, lru)
  		x += get_count(page);
  	spin_unlock_irqrestore(&n->list_lock, flags);
  	return x;
  }
  #endif /* CONFIG_SLUB_DEBUG || CONFIG_SYSFS */
  
  static noinline void
  slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid)
  {
  #ifdef CONFIG_SLUB_DEBUG
  	static DEFINE_RATELIMIT_STATE(slub_oom_rs, DEFAULT_RATELIMIT_INTERVAL,
  				      DEFAULT_RATELIMIT_BURST);
  	int node;
  	struct kmem_cache_node *n;
  
  	if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slub_oom_rs))
  		return;
  
  	pr_warn("SLUB: Unable to allocate memory on node %d, gfp=%#x(%pGg)\n",
  		nid, gfpflags, &gfpflags);
  	pr_warn("  cache: %s, object size: %u, buffer size: %u, default order: %u, min order: %u\n",
  		s->name, s->object_size, s->size, oo_order(s->oo),
  		oo_order(s->min));
  
  	if (oo_order(s->min) > get_order(s->object_size))
  		pr_warn("  %s debugging increased min order, use slub_debug=O to disable.\n",
  			s->name);
  
  	for_each_kmem_cache_node(s, node, n) {
  		unsigned long nr_slabs;
  		unsigned long nr_objs;
  		unsigned long nr_free;
  
  		nr_free  = count_partial(n, count_free);
  		nr_slabs = node_nr_slabs(n);
  		nr_objs  = node_nr_objs(n);
  
  		pr_warn("  node %d: slabs: %ld, objs: %ld, free: %ld\n",
  			node, nr_slabs, nr_objs, nr_free);
  	}
  #endif
  }
  
  static inline void *new_slab_objects(struct kmem_cache *s, gfp_t flags,
  			int node, struct kmem_cache_cpu **pc)
  {
  	void *freelist;
  	struct kmem_cache_cpu *c = *pc;
  	struct page *page;
  
  	freelist = get_partial(s, flags, node, c);
  
  	if (freelist)
  		return freelist;
  
  	page = new_slab(s, flags, node);
  	if (page) {
  		c = raw_cpu_ptr(s->cpu_slab);
  		if (c->page)
  			flush_slab(s, c);
  
  		/*
  		 * No other reference to the page yet so we can
  		 * muck around with it freely without cmpxchg
  		 */
  		freelist = page->freelist;
  		page->freelist = NULL;
  
  		stat(s, ALLOC_SLAB);
  		c->page = page;
  		*pc = c;
  	} else
  		freelist = NULL;
  
  	return freelist;
  }
  
  static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags)
  {
  	if (unlikely(PageSlabPfmemalloc(page)))
  		return gfp_pfmemalloc_allowed(gfpflags);
  
  	return true;
  }
  
  /*
   * Check the page->freelist of a page and either transfer the freelist to the
   * per cpu freelist or deactivate the page.
   *
   * The page is still frozen if the return value is not NULL.
   *
   * If this function returns NULL then the page has been unfrozen.
   *
   * This function must be called with interrupt disabled.
   */
  static inline void *get_freelist(struct kmem_cache *s, struct page *page)
  {
  	struct page new;
  	unsigned long counters;
  	void *freelist;
  
  	do {
  		freelist = page->freelist;
  		counters = page->counters;
  
  		new.counters = counters;
  		VM_BUG_ON(!new.frozen);
  
  		new.inuse = page->objects;
  		new.frozen = freelist != NULL;
  
  	} while (!__cmpxchg_double_slab(s, page,
  		freelist, counters,
  		NULL, new.counters,
  		"get_freelist"));
  
  	return freelist;
  }
  
  /*
   * Slow path. The lockless freelist is empty or we need to perform
   * debugging duties.
   *
   * Processing is still very fast if new objects have been freed to the
   * regular freelist. In that case we simply take over the regular freelist
   * as the lockless freelist and zap the regular freelist.
   *
   * If that is not working then we fall back to the partial lists. We take the
   * first element of the freelist as the object to allocate now and move the
   * rest of the freelist to the lockless freelist.
   *
   * And if we were unable to get a new slab from the partial slab lists then
   * we need to allocate a new slab. This is the slowest path since it involves
   * a call to the page allocator and the setup of a new slab.
   *
   * Version of __slab_alloc to use when we know that interrupts are
   * already disabled (which is the case for bulk allocation).
   */
  static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
  			  unsigned long addr, struct kmem_cache_cpu *c)
  {
  	void *freelist;
  	struct page *page;
  
  	page = c->page;
  	if (!page)
  		goto new_slab;
  redo:
  
  	if (unlikely(!node_match(page, node))) {
  		int searchnode = node;
  
  		if (node != NUMA_NO_NODE && !node_present_pages(node))
  			searchnode = node_to_mem_node(node);
  
  		if (unlikely(!node_match(page, searchnode))) {
  			stat(s, ALLOC_NODE_MISMATCH);
  			deactivate_slab(s, page, c->freelist, c);
  			goto new_slab;
  		}
  	}
  
  	/*
  	 * By rights, we should be searching for a slab page that was
  	 * PFMEMALLOC but right now, we are losing the pfmemalloc
  	 * information when the page leaves the per-cpu allocator
  	 */
  	if (unlikely(!pfmemalloc_match(page, gfpflags))) {
  		deactivate_slab(s, page, c->freelist, c);
  		goto new_slab;
  	}
  
  	/* must check again c->freelist in case of cpu migration or IRQ */
  	freelist = c->freelist;
  	if (freelist)
  		goto load_freelist;
  
  	freelist = get_freelist(s, page);
  
  	if (!freelist) {
  		c->page = NULL;
  		stat(s, DEACTIVATE_BYPASS);
  		goto new_slab;
  	}
  
  	stat(s, ALLOC_REFILL);
  
  load_freelist:
  	/*
  	 * freelist is pointing to the list of objects to be used.
  	 * page is pointing to the page from which the objects are obtained.
  	 * That page must be frozen for per cpu allocations to work.
  	 */
  	VM_BUG_ON(!c->page->frozen);
  	c->freelist = get_freepointer(s, freelist);
  	c->tid = next_tid(c->tid);
  	return freelist;
  
  new_slab:
  
  	if (slub_percpu_partial(c)) {
  		page = c->page = slub_percpu_partial(c);
  		slub_set_percpu_partial(c, page);
  		stat(s, CPU_PARTIAL_ALLOC);
  		goto redo;
  	}
  
  	freelist = new_slab_objects(s, gfpflags, node, &c);
  
  	if (unlikely(!freelist)) {
  		slab_out_of_memory(s, gfpflags, node);
  		return NULL;
  	}
  
  	page = c->page;
  	if (likely(!kmem_cache_debug(s) && pfmemalloc_match(page, gfpflags)))
  		goto load_freelist;
  
  	/* Only entered in the debug case */
  	if (kmem_cache_debug(s) &&
  			!alloc_debug_processing(s, page, freelist, addr))
  		goto new_slab;	/* Slab failed checks. Next slab needed */
  
  	deactivate_slab(s, page, get_freepointer(s, freelist), c);
  	return freelist;
  }
  
  /*
   * Another one that disabled interrupt and compensates for possible
   * cpu changes by refetching the per cpu area pointer.
   */
  static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
  			  unsigned long addr, struct kmem_cache_cpu *c)
  {
  	void *p;
  	unsigned long flags;
  
  	local_irq_save(flags);
  #ifdef CONFIG_PREEMPT
  	/*
  	 * We may have been preempted and rescheduled on a different
  	 * cpu before disabling interrupts. Need to reload cpu area
  	 * pointer.
  	 */
  	c = this_cpu_ptr(s->cpu_slab);
  #endif
  
  	p = ___slab_alloc(s, gfpflags, node, addr, c);
  	local_irq_restore(flags);
  	return p;
  }
  
  /*
   * Inlined fastpath so that allocation functions (kmalloc, kmem_cache_alloc)
   * have the fastpath folded into their functions. So no function call
   * overhead for requests that can be satisfied on the fastpath.
   *
   * The fastpath works by first checking if the lockless freelist can be used.
   * If not then __slab_alloc is called for slow processing.
   *
   * Otherwise we can simply pick the next object from the lockless free list.
   */
  static __always_inline void *slab_alloc_node(struct kmem_cache *s,
  		gfp_t gfpflags, int node, unsigned long addr)
  {
  	void *object;
  	struct kmem_cache_cpu *c;
  	struct page *page;
  	unsigned long tid;
  
  	s = slab_pre_alloc_hook(s, gfpflags);
  	if (!s)
  		return NULL;
  redo:
  	/*
  	 * Must read kmem_cache cpu data via this cpu ptr. Preemption is
  	 * enabled. We may switch back and forth between cpus while
  	 * reading from one cpu area. That does not matter as long
  	 * as we end up on the original cpu again when doing the cmpxchg.
  	 *
  	 * We should guarantee that tid and kmem_cache are retrieved on
  	 * the same cpu. It could be different if CONFIG_PREEMPT so we need
  	 * to check if it is matched or not.
  	 */
  	do {
  		tid = this_cpu_read(s->cpu_slab->tid);
  		c = raw_cpu_ptr(s->cpu_slab);
  	} while (IS_ENABLED(CONFIG_PREEMPT) &&
  		 unlikely(tid != READ_ONCE(c->tid)));
  
  	/*
  	 * Irqless object alloc/free algorithm used here depends on sequence
  	 * of fetching cpu_slab's data. tid should be fetched before anything
  	 * on c to guarantee that object and page associated with previous tid
  	 * won't be used with current tid. If we fetch tid first, object and
  	 * page could be one associated with next tid and our alloc/free
  	 * request will be failed. In this case, we will retry. So, no problem.
  	 */
  	barrier();
  
  	/*
  	 * The transaction ids are globally unique per cpu and per operation on
  	 * a per cpu queue. Thus they can be guarantee that the cmpxchg_double
  	 * occurs on the right processor and that there was no operation on the
  	 * linked list in between.
  	 */
  
  	object = c->freelist;
  	page = c->page;
  	if (unlikely(!object || !node_match(page, node))) {
  		object = __slab_alloc(s, gfpflags, node, addr, c);
  		stat(s, ALLOC_SLOWPATH);
  	} else {
  		void *next_object = get_freepointer_safe(s, object);
  
  		/*
  		 * The cmpxchg will only match if there was no additional
  		 * operation and if we are on the right processor.
  		 *
  		 * The cmpxchg does the following atomically (without lock
  		 * semantics!)
  		 * 1. Relocate first pointer to the current per cpu area.
  		 * 2. Verify that tid and freelist have not been changed
  		 * 3. If they were not changed replace tid and freelist
  		 *
  		 * Since this is without lock semantics the protection is only
  		 * against code executing on this cpu *not* from access by
  		 * other cpus.
  		 */
  		if (unlikely(!this_cpu_cmpxchg_double(
  				s->cpu_slab->freelist, s->cpu_slab->tid,
  				object, tid,
  				next_object, next_tid(tid)))) {
  
  			note_cmpxchg_failure("slab_alloc", s, tid);
  			goto redo;
  		}
  		prefetch_freepointer(s, next_object);
  		stat(s, ALLOC_FASTPATH);
  	}
  
  	if (unlikely(gfpflags & __GFP_ZERO) && object)
  		memset(object, 0, s->object_size);
  
  	slab_post_alloc_hook(s, gfpflags, 1, &object);
  
  	return object;
  }
  
  static __always_inline void *slab_alloc(struct kmem_cache *s,
  		gfp_t gfpflags, unsigned long addr)
  {
  	return slab_alloc_node(s, gfpflags, NUMA_NO_NODE, addr);
  }
  
  void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags)
  {
  	void *ret = slab_alloc(s, gfpflags, _RET_IP_);
  
  	trace_kmem_cache_alloc(_RET_IP_, ret, s->object_size,
  				s->size, gfpflags);
  
  	return ret;
  }
  EXPORT_SYMBOL(kmem_cache_alloc);
  
  #ifdef CONFIG_TRACING
  void *kmem_cache_alloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size)
  {
  	void *ret = slab_alloc(s, gfpflags, _RET_IP_);
  	trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags);
  	kasan_kmalloc(s, ret, size, gfpflags);
  	return ret;
  }
  EXPORT_SYMBOL(kmem_cache_alloc_trace);
  #endif
  
  #ifdef CONFIG_NUMA
  void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node)
  {
  	void *ret = slab_alloc_node(s, gfpflags, node, _RET_IP_);
  
  	trace_kmem_cache_alloc_node(_RET_IP_, ret,
  				    s->object_size, s->size, gfpflags, node);
  
  	return ret;
  }
  EXPORT_SYMBOL(kmem_cache_alloc_node);
  
  #ifdef CONFIG_TRACING
  void *kmem_cache_alloc_node_trace(struct kmem_cache *s,
  				    gfp_t gfpflags,
  				    int node, size_t size)
  {
  	void *ret = slab_alloc_node(s, gfpflags, node, _RET_IP_);
  
  	trace_kmalloc_node(_RET_IP_, ret,
  			   size, s->size, gfpflags, node);
  
  	kasan_kmalloc(s, ret, size, gfpflags);
  	return ret;
  }
  EXPORT_SYMBOL(kmem_cache_alloc_node_trace);
  #endif
  #endif
  
  /*
   * Slow path handling. This may still be called frequently since objects
   * have a longer lifetime than the cpu slabs in most processing loads.
   *
   * So we still attempt to reduce cache line usage. Just take the slab
   * lock and free the item. If there is no additional partial page
   * handling required then we can return immediately.
   */
  static void __slab_free(struct kmem_cache *s, struct page *page,
  			void *head, void *tail, int cnt,
  			unsigned long addr)
  
  {
  	void *prior;
  	int was_frozen;
  	struct page new;
  	unsigned long counters;
  	struct kmem_cache_node *n = NULL;
  	unsigned long uninitialized_var(flags);
  
  	stat(s, FREE_SLOWPATH);
  
  	if (kmem_cache_debug(s) &&
  	    !free_debug_processing(s, page, head, tail, cnt, addr))
  		return;
  
  	do {
  		if (unlikely(n)) {
  			spin_unlock_irqrestore(&n->list_lock, flags);
  			n = NULL;
  		}
  		prior = page->freelist;
  		counters = page->counters;
  		set_freepointer(s, tail, prior);
  		new.counters = counters;
  		was_frozen = new.frozen;
  		new.inuse -= cnt;
  		if ((!new.inuse || !prior) && !was_frozen) {
  
  			if (kmem_cache_has_cpu_partial(s) && !prior) {
  
  				/*
  				 * Slab was on no list before and will be
  				 * partially empty
  				 * We can defer the list move and instead
  				 * freeze it.
  				 */
  				new.frozen = 1;
  
  			} else { /* Needs to be taken off a list */
  
  				n = get_node(s, page_to_nid(page));
  				/*
  				 * Speculatively acquire the list_lock.
  				 * If the cmpxchg does not succeed then we may
  				 * drop the list_lock without any processing.
  				 *
  				 * Otherwise the list_lock will synchronize with
  				 * other processors updating the list of slabs.
  				 */
  				spin_lock_irqsave(&n->list_lock, flags);
  
  			}
  		}
  
  	} while (!cmpxchg_double_slab(s, page,
  		prior, counters,
  		head, new.counters,
  		"__slab_free"));
  
  	if (likely(!n)) {
  
  		/*
  		 * If we just froze the page then put it onto the
  		 * per cpu partial list.
  		 */
  		if (new.frozen && !was_frozen) {
  			put_cpu_partial(s, page, 1);
  			stat(s, CPU_PARTIAL_FREE);
  		}
  		/*
  		 * The list lock was not taken therefore no list
  		 * activity can be necessary.
  		 */
  		if (was_frozen)
  			stat(s, FREE_FROZEN);
  		return;
  	}
  
  	if (unlikely(!new.inuse && n->nr_partial >= s->min_partial))
  		goto slab_empty;
  
  	/*
  	 * Objects left in the slab. If it was not on the partial list before
  	 * then add it.
  	 */
  	if (!kmem_cache_has_cpu_partial(s) && unlikely(!prior)) {
  		if (kmem_cache_debug(s))
  			remove_full(s, n, page);
  		add_partial(n, page, DEACTIVATE_TO_TAIL);
  		stat(s, FREE_ADD_PARTIAL);
  	}
  	spin_unlock_irqrestore(&n->list_lock, flags);
  	return;
  
  slab_empty:
  	if (prior) {
  		/*
  		 * Slab on the partial list.
  		 */
  		remove_partial(n, page);
  		stat(s, FREE_REMOVE_PARTIAL);
  	} else {
  		/* Slab must be on the full list */
  		remove_full(s, n, page);
  	}
  
  	spin_unlock_irqrestore(&n->list_lock, flags);
  	stat(s, FREE_SLAB);
  	discard_slab(s, page);
  }
  
  /*
   * Fastpath with forced inlining to produce a kfree and kmem_cache_free that
   * can perform fastpath freeing without additional function calls.
   *
   * The fastpath is only possible if we are freeing to the current cpu slab
   * of this processor. This typically the case if we have just allocated
   * the item before.
   *
   * If fastpath is not possible then fall back to __slab_free where we deal
   * with all sorts of special processing.
   *
   * Bulk free of a freelist with several objects (all pointing to the
   * same page) possible by specifying head and tail ptr, plus objects
   * count (cnt). Bulk free indicated by tail pointer being set.
   */
  static __always_inline void do_slab_free(struct kmem_cache *s,
  				struct page *page, void *head, void *tail,
  				int cnt, unsigned long addr)
  {
  	void *tail_obj = tail ? : head;
  	struct kmem_cache_cpu *c;
  	unsigned long tid;
  redo:
  	/*
  	 * Determine the currently cpus per cpu slab.
  	 * The cpu may change afterward. However that does not matter since
  	 * data is retrieved via this pointer. If we are on the same cpu
  	 * during the cmpxchg then the free will succeed.
  	 */
  	do {
  		tid = this_cpu_read(s->cpu_slab->tid);
  		c = raw_cpu_ptr(s->cpu_slab);
  	} while (IS_ENABLED(CONFIG_PREEMPT) &&
  		 unlikely(tid != READ_ONCE(c->tid)));
  
  	/* Same with comment on barrier() in slab_alloc_node() */
  	barrier();
  
  	if (likely(page == c->page)) {
  		set_freepointer(s, tail_obj, c->freelist);
  
  		if (unlikely(!this_cpu_cmpxchg_double(
  				s->cpu_slab->freelist, s->cpu_slab->tid,
  				c->freelist, tid,
  				head, next_tid(tid)))) {
  
  			note_cmpxchg_failure("slab_free", s, tid);
  			goto redo;
  		}
  		stat(s, FREE_FASTPATH);
  	} else
  		__slab_free(s, page, head, tail_obj, cnt, addr);
  
  }
  
  static __always_inline void slab_free(struct kmem_cache *s, struct page *page,
  				      void *head, void *tail, int cnt,
  				      unsigned long addr)
  {
  	/*
  	 * With KASAN enabled slab_free_freelist_hook modifies the freelist
  	 * to remove objects, whose reuse must be delayed.
  	 */
  	if (slab_free_freelist_hook(s, &head, &tail))
  		do_slab_free(s, page, head, tail, cnt, addr);
  }
  
  #ifdef CONFIG_KASAN
  void ___cache_free(struct kmem_cache *cache, void *x, unsigned long addr)
  {
  	do_slab_free(cache, virt_to_head_page(x), x, NULL, 1, addr);
  }
  #endif
  
  void kmem_cache_free(struct kmem_cache *s, void *x)
  {
  	s = cache_from_obj(s, x);
  	if (!s)
  		return;
  	slab_free(s, virt_to_head_page(x), x, NULL, 1, _RET_IP_);
  	trace_kmem_cache_free(_RET_IP_, x);
  }
  EXPORT_SYMBOL(kmem_cache_free);
  
  struct detached_freelist {
  	struct page *page;
  	void *tail;
  	void *freelist;
  	int cnt;
  	struct kmem_cache *s;
  };
  
  /*
   * This function progressively scans the array with free objects (with
   * a limited look ahead) and extract objects belonging to the same
   * page.  It builds a detached freelist directly within the given
   * page/objects.  This can happen without any need for
   * synchronization, because the objects are owned by running process.
   * The freelist is build up as a single linked list in the objects.
   * The idea is, that this detached freelist can then be bulk
   * transferred to the real freelist(s), but only requiring a single
   * synchronization primitive.  Look ahead in the array is limited due
   * to performance reasons.
   */
  static inline
  int build_detached_freelist(struct kmem_cache *s, size_t size,
  			    void **p, struct detached_freelist *df)
  {
  	size_t first_skipped_index = 0;
  	int lookahead = 3;
  	void *object;
  	struct page *page;
  
  	/* Always re-init detached_freelist */
  	df->page = NULL;
  
  	do {
  		object = p[--size];
  		/* Do we need !ZERO_OR_NULL_PTR(object) here? (for kfree) */
  	} while (!object && size);
  
  	if (!object)
  		return 0;
  
  	page = virt_to_head_page(object);
  	if (!s) {
  		/* Handle kalloc'ed objects */
  		if (unlikely(!PageSlab(page))) {
  			BUG_ON(!PageCompound(page));
  			kfree_hook(object);
  			__free_pages(page, compound_order(page));
  			p[size] = NULL; /* mark object processed */
  			return size;
  		}
  		/* Derive kmem_cache from object */
  		df->s = page->slab_cache;
  	} else {
  		df->s = cache_from_obj(s, object); /* Support for memcg */
  	}
  
  	/* Start new detached freelist */
  	df->page = page;
  	set_freepointer(df->s, object, NULL);
  	df->tail = object;
  	df->freelist = object;
  	p[size] = NULL; /* mark object processed */
  	df->cnt = 1;
  
  	while (size) {
  		object = p[--size];
  		if (!object)
  			continue; /* Skip processed objects */
  
  		/* df->page is always set at this point */
  		if (df->page == virt_to_head_page(object)) {
  			/* Opportunity build freelist */
  			set_freepointer(df->s, object, df->freelist);
  			df->freelist = object;
  			df->cnt++;
  			p[size] = NULL; /* mark object processed */
  
  			continue;
  		}
  
  		/* Limit look ahead search */
  		if (!--lookahead)
  			break;
  
  		if (!first_skipped_index)
  			first_skipped_index = size + 1;
  	}
  
  	return first_skipped_index;
  }
  
  /* Note that interrupts must be enabled when calling this function. */
  void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p)
  {
  	if (WARN_ON(!size))
  		return;
  
  	do {
  		struct detached_freelist df;
  
  		size = build_detached_freelist(s, size, p, &df);
  		if (!df.page)
  			continue;
  
  		slab_free(df.s, df.page, df.freelist, df.tail, df.cnt,_RET_IP_);
  	} while (likely(size));
  }
  EXPORT_SYMBOL(kmem_cache_free_bulk);
  
  /* Note that interrupts must be enabled when calling this function. */
  int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
  			  void **p)
  {
  	struct kmem_cache_cpu *c;
  	int i;
  
  	/* memcg and kmem_cache debug support */
  	s = slab_pre_alloc_hook(s, flags);
  	if (unlikely(!s))
  		return false;
  	/*
  	 * Drain objects in the per cpu slab, while disabling local
  	 * IRQs, which protects against PREEMPT and interrupts
  	 * handlers invoking normal fastpath.
  	 */
  	local_irq_disable();
  	c = this_cpu_ptr(s->cpu_slab);
  
  	for (i = 0; i < size; i++) {
  		void *object = c->freelist;
  
  		if (unlikely(!object)) {
  			/*
  			 * Invoking slow path likely have side-effect
  			 * of re-populating per CPU c->freelist
  			 */
  			p[i] = ___slab_alloc(s, flags, NUMA_NO_NODE,
  					    _RET_IP_, c);
  			if (unlikely(!p[i]))
  				goto error;
  
  			c = this_cpu_ptr(s->cpu_slab);
  			continue; /* goto for-loop */
  		}
  		c->freelist = get_freepointer(s, object);
  		p[i] = object;
  	}
  	c->tid = next_tid(c->tid);
  	local_irq_enable();
  
  	/* Clear memory outside IRQ disabled fastpath loop */
  	if (unlikely(flags & __GFP_ZERO)) {
  		int j;
  
  		for (j = 0; j < i; j++)
  			memset(p[j], 0, s->object_size);
  	}
  
  	/* memcg and kmem_cache debug support */
  	slab_post_alloc_hook(s, flags, size, p);
  	return i;
  error:
  	local_irq_enable();
  	slab_post_alloc_hook(s, flags, i, p);
  	__kmem_cache_free_bulk(s, i, p);
  	return 0;
  }
  EXPORT_SYMBOL(kmem_cache_alloc_bulk);
  
  
  /*
   * Object placement in a slab is made very easy because we always start at
   * offset 0. If we tune the size of the object to the alignment then we can
   * get the required alignment by putting one properly sized object after
   * another.
   *
   * Notice that the allocation order determines the sizes of the per cpu
   * caches. Each processor has always one slab available for allocations.
   * Increasing the allocation order reduces the number of times that slabs
   * must be moved on and off the partial lists and is therefore a factor in
   * locking overhead.
   */
  
  /*
   * Mininum / Maximum order of slab pages. This influences locking overhead
   * and slab fragmentation. A higher order reduces the number of partial slabs
   * and increases the number of allocations possible without having to
   * take the list_lock.
   */
  static unsigned int slub_min_order;
  static unsigned int slub_max_order = PAGE_ALLOC_COSTLY_ORDER;
  static unsigned int slub_min_objects;
  
  /*
   * Calculate the order of allocation given an slab object size.
   *
   * The order of allocation has significant impact on performance and other
   * system components. Generally order 0 allocations should be preferred since
   * order 0 does not cause fragmentation in the page allocator. Larger objects
   * be problematic to put into order 0 slabs because there may be too much
   * unused space left. We go to a higher order if more than 1/16th of the slab
   * would be wasted.
   *
   * In order to reach satisfactory performance we must ensure that a minimum
   * number of objects is in one slab. Otherwise we may generate too much
   * activity on the partial lists which requires taking the list_lock. This is
   * less a concern for large slabs though which are rarely used.
   *
   * slub_max_order specifies the order where we begin to stop considering the
   * number of objects in a slab as critical. If we reach slub_max_order then
   * we try to keep the page order as low as possible. So we accept more waste
   * of space in favor of a small page order.
   *
   * Higher order allocations also allow the placement of more objects in a
   * slab and thereby reduce object handling overhead. If the user has
   * requested a higher mininum order then we start with that one instead of
   * the smallest order which will fit the object.
   */
  static inline unsigned int slab_order(unsigned int size,
  		unsigned int min_objects, unsigned int max_order,
  		unsigned int fract_leftover, unsigned int reserved)
  {
  	unsigned int min_order = slub_min_order;
  	unsigned int order;
  
  	if (order_objects(min_order, size, reserved) > MAX_OBJS_PER_PAGE)
  		return get_order(size * MAX_OBJS_PER_PAGE) - 1;
  
  	for (order = max(min_order, (unsigned int)get_order(min_objects * size + reserved));
  			order <= max_order; order++) {
  
  		unsigned int slab_size = (unsigned int)PAGE_SIZE << order;
  		unsigned int rem;
  
  		rem = (slab_size - reserved) % size;
  
  		if (rem <= slab_size / fract_leftover)
  			break;
  	}
  
  	return order;
  }
  
  static inline int calculate_order(unsigned int size, unsigned int reserved)
  {
  	unsigned int order;
  	unsigned int min_objects;
  	unsigned int max_objects;
  
  	/*
  	 * Attempt to find best configuration for a slab. This
  	 * works by first attempting to generate a layout with
  	 * the best configuration and backing off gradually.
  	 *
  	 * First we increase the acceptable waste in a slab. Then
  	 * we reduce the minimum objects required in a slab.
  	 */
  	min_objects = slub_min_objects;
  	if (!min_objects)
  		min_objects = 4 * (fls(nr_cpu_ids) + 1);
  	max_objects = order_objects(slub_max_order, size, reserved);
  	min_objects = min(min_objects, max_objects);
  
  	while (min_objects > 1) {
  		unsigned int fraction;
  
  		fraction = 16;
  		while (fraction >= 4) {
  			order = slab_order(size, min_objects,
  					slub_max_order, fraction, reserved);
  			if (order <= slub_max_order)
  				return order;
  			fraction /= 2;
  		}
  		min_objects--;
  	}
  
  	/*
  	 * We were unable to place multiple objects in a slab. Now
  	 * lets see if we can place a single object there.
  	 */
  	order = slab_order(size, 1, slub_max_order, 1, reserved);
  	if (order <= slub_max_order)
  		return order;
  
  	/*
  	 * Doh this slab cannot be placed using slub_max_order.
  	 */
  	order = slab_order(size, 1, MAX_ORDER, 1, reserved);
  	if (order < MAX_ORDER)
  		return order;
  	return -ENOSYS;
  }
  
  static void
  init_kmem_cache_node(struct kmem_cache_node *n)
  {
  	n->nr_partial = 0;
  	spin_lock_init(&n->list_lock);
  	INIT_LIST_HEAD(&n->partial);
  #ifdef CONFIG_SLUB_DEBUG
  	atomic_long_set(&n->nr_slabs, 0);
  	atomic_long_set(&n->total_objects, 0);
  	INIT_LIST_HEAD(&n->full);
  #endif
  }
  
  static inline int alloc_kmem_cache_cpus(struct kmem_cache *s)
  {
  	BUILD_BUG_ON(PERCPU_DYNAMIC_EARLY_SIZE <
  			KMALLOC_SHIFT_HIGH * sizeof(struct kmem_cache_cpu));
  
  	/*
  	 * Must align to double word boundary for the double cmpxchg
  	 * instructions to work; see __pcpu_double_call_return_bool().
  	 */
  	s->cpu_slab = __alloc_percpu(sizeof(struct kmem_cache_cpu),
  				     2 * sizeof(void *));
  
  	if (!s->cpu_slab)
  		return 0;
  
  	init_kmem_cache_cpus(s);
  
  	return 1;
  }
  
  static struct kmem_cache *kmem_cache_node;
  
  /*
   * No kmalloc_node yet so do it by hand. We know that this is the first
   * slab on the node for this slabcache. There are no concurrent accesses
   * possible.
   *
   * Note that this function only works on the kmem_cache_node
   * when allocating for the kmem_cache_node. This is used for bootstrapping
   * memory on a fresh node that has no slab structures yet.
   */
  static void early_kmem_cache_node_alloc(int node)
  {
  	struct page *page;
  	struct kmem_cache_node *n;
  
  	BUG_ON(kmem_cache_node->size < sizeof(struct kmem_cache_node));
  
  	page = new_slab(kmem_cache_node, GFP_NOWAIT, node);
  
  	BUG_ON(!page);
  	if (page_to_nid(page) != node) {
  		pr_err("SLUB: Unable to allocate memory from node %d\n", node);
  		pr_err("SLUB: Allocating a useless per node structure in order to be able to continue\n");
  	}
  
  	n = page->freelist;
  	BUG_ON(!n);
  	page->freelist = get_freepointer(kmem_cache_node, n);
  	page->inuse = 1;
  	page->frozen = 0;
  	kmem_cache_node->node[node] = n;
  #ifdef CONFIG_SLUB_DEBUG
  	init_object(kmem_cache_node, n, SLUB_RED_ACTIVE);
  	init_tracking(kmem_cache_node, n);
  #endif
  	kasan_kmalloc(kmem_cache_node, n, sizeof(struct kmem_cache_node),
  		      GFP_KERNEL);
  	init_kmem_cache_node(n);
  	inc_slabs_node(kmem_cache_node, node, page->objects);
  
  	/*
  	 * No locks need to be taken here as it has just been
  	 * initialized and there is no concurrent access.
  	 */
  	__add_partial(n, page, DEACTIVATE_TO_HEAD);
  }
  
  static void free_kmem_cache_nodes(struct kmem_cache *s)
  {
  	int node;
  	struct kmem_cache_node *n;
  
  	for_each_kmem_cache_node(s, node, n) {
  		s->node[node] = NULL;
  		kmem_cache_free(kmem_cache_node, n);
  	}
  }
  
  void __kmem_cache_release(struct kmem_cache *s)
  {
  	cache_random_seq_destroy(s);
  	free_percpu(s->cpu_slab);
  	free_kmem_cache_nodes(s);
  }
  
  static int init_kmem_cache_nodes(struct kmem_cache *s)
  {
  	int node;
  
  	for_each_node_state(node, N_NORMAL_MEMORY) {
  		struct kmem_cache_node *n;
  
  		if (slab_state == DOWN) {
  			early_kmem_cache_node_alloc(node);
  			continue;
  		}
  		n = kmem_cache_alloc_node(kmem_cache_node,
  						GFP_KERNEL, node);
  
  		if (!n) {
  			free_kmem_cache_nodes(s);
  			return 0;
  		}
  
  		init_kmem_cache_node(n);
  		s->node[node] = n;
  	}
  	return 1;
  }
  
  static void set_min_partial(struct kmem_cache *s, unsigned long min)
  {
  	if (min < MIN_PARTIAL)
  		min = MIN_PARTIAL;
  	else if (min > MAX_PARTIAL)
  		min = MAX_PARTIAL;
  	s->min_partial = min;
  }
  
  static void set_cpu_partial(struct kmem_cache *s)
  {
  #ifdef CONFIG_SLUB_CPU_PARTIAL
  	/*
  	 * cpu_partial determined the maximum number of objects kept in the
  	 * per cpu partial lists of a processor.
  	 *
  	 * Per cpu partial lists mainly contain slabs that just have one
  	 * object freed. If they are used for allocation then they can be
  	 * filled up again with minimal effort. The slab will never hit the
  	 * per node partial lists and therefore no locking will be required.
  	 *
  	 * This setting also determines
  	 *
  	 * A) The number of objects from per cpu partial slabs dumped to the
  	 *    per node list when we reach the limit.
  	 * B) The number of objects in cpu partial slabs to extract from the
  	 *    per node list when we run out of per cpu objects. We only fetch
  	 *    50% to keep some capacity around for frees.
  	 */
  	if (!kmem_cache_has_cpu_partial(s))
  		s->cpu_partial = 0;
  	else if (s->size >= PAGE_SIZE)
  		s->cpu_partial = 2;
  	else if (s->size >= 1024)
  		s->cpu_partial = 6;
  	else if (s->size >= 256)
  		s->cpu_partial = 13;
  	else
  		s->cpu_partial = 30;
  #endif
  }
  
  /*
   * calculate_sizes() determines the order and the distribution of data within
   * a slab object.
   */
  static int calculate_sizes(struct kmem_cache *s, int forced_order)
  {
  	slab_flags_t flags = s->flags;
  	unsigned int size = s->object_size;
  	unsigned int order;
  
  	/*
  	 * Round up object size to the next word boundary. We can only
  	 * place the free pointer at word boundaries and this determines
  	 * the possible location of the free pointer.
  	 */
  	size = ALIGN(size, sizeof(void *));
  
  #ifdef CONFIG_SLUB_DEBUG
  	/*
  	 * Determine if we can poison the object itself. If the user of
  	 * the slab may touch the object after free or before allocation
  	 * then we should never poison the object itself.
  	 */
  	if ((flags & SLAB_POISON) && !(flags & SLAB_TYPESAFE_BY_RCU) &&
  			!s->ctor)
  		s->flags |= __OBJECT_POISON;
  	else
  		s->flags &= ~__OBJECT_POISON;
  
  
  	/*
  	 * If we are Redzoning then check if there is some space between the
  	 * end of the object and the free pointer. If not then add an
  	 * additional word to have some bytes to store Redzone information.
  	 */
  	if ((flags & SLAB_RED_ZONE) && size == s->object_size)
  		size += sizeof(void *);
  #endif
  
  	/*
  	 * With that we have determined the number of bytes in actual use
  	 * by the object. This is the potential offset to the free pointer.
  	 */
  	s->inuse = size;
  
  	if (((flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)) ||
  		s->ctor)) {
  		/*
  		 * Relocate free pointer after the object if it is not
  		 * permitted to overwrite the first word of the object on
  		 * kmem_cache_free.
  		 *
  		 * This is the case if we do RCU, have a constructor or
  		 * destructor or are poisoning the objects.
  		 */
  		s->offset = size;
  		size += sizeof(void *);
  	}
  
  #ifdef CONFIG_SLUB_DEBUG
  	if (flags & SLAB_STORE_USER)
  		/*
  		 * Need to store information about allocs and frees after
  		 * the object.
  		 */
  		size += 2 * sizeof(struct track);
  #endif
  
  	kasan_cache_create(s, &size, &s->flags);
  #ifdef CONFIG_SLUB_DEBUG
  	if (flags & SLAB_RED_ZONE) {
  		/*
  		 * Add some empty padding so that we can catch
  		 * overwrites from earlier objects rather than let
  		 * tracking information or the free pointer be
  		 * corrupted if a user writes before the start
  		 * of the object.
  		 */
  		size += sizeof(void *);
  
  		s->red_left_pad = sizeof(void *);
  		s->red_left_pad = ALIGN(s->red_left_pad, s->align);
  		size += s->red_left_pad;
  	}
  #endif
  
  	/*
  	 * SLUB stores one object immediately after another beginning from
  	 * offset 0. In order to align the objects we have to simply size
  	 * each object to conform to the alignment.
  	 */
  	size = ALIGN(size, s->align);
  	s->size = size;
  	if (forced_order >= 0)
  		order = forced_order;
  	else
  		order = calculate_order(size, s->reserved);
  
  	if ((int)order < 0)
  		return 0;
  
  	s->allocflags = 0;
  	if (order)
  		s->allocflags |= __GFP_COMP;
  
  	if (s->flags & SLAB_CACHE_DMA)
  		s->allocflags |= GFP_DMA;
  
  	if (s->flags & SLAB_RECLAIM_ACCOUNT)
  		s->allocflags |= __GFP_RECLAIMABLE;
  
  	/*
  	 * Determine the number of objects per slab
  	 */
  	s->oo = oo_make(order, size, s->reserved);
  	s->min = oo_make(get_order(size), size, s->reserved);
  	if (oo_objects(s->oo) > oo_objects(s->max))
  		s->max = s->oo;
  
  	return !!oo_objects(s->oo);
  }
  
  static int kmem_cache_open(struct kmem_cache *s, slab_flags_t flags)
  {
  	s->flags = kmem_cache_flags(s->size, flags, s->name, s->ctor);
  	s->reserved = 0;
  #ifdef CONFIG_SLAB_FREELIST_HARDENED
  	s->random = get_random_long();
  #endif
  
  	if (need_reserve_slab_rcu && (s->flags & SLAB_TYPESAFE_BY_RCU))
  		s->reserved = sizeof(struct rcu_head);
  
  	if (!calculate_sizes(s, -1))
  		goto error;
  	if (disable_higher_order_debug) {
  		/*
  		 * Disable debugging flags that store metadata if the min slab
  		 * order increased.
  		 */
  		if (get_order(s->size) > get_order(s->object_size)) {
  			s->flags &= ~DEBUG_METADATA_FLAGS;
  			s->offset = 0;
  			if (!calculate_sizes(s, -1))
  				goto error;
  		}
  	}
  
  #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
      defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
  	if (system_has_cmpxchg_double() && (s->flags & SLAB_NO_CMPXCHG) == 0)
  		/* Enable fast mode */
  		s->flags |= __CMPXCHG_DOUBLE;
  #endif
  
  	/*
  	 * The larger the object size is, the more pages we want on the partial
  	 * list to avoid pounding the page allocator excessively.
  	 */
  	set_min_partial(s, ilog2(s->size) / 2);
  
  	set_cpu_partial(s);
  
  #ifdef CONFIG_NUMA
  	s->remote_node_defrag_ratio = 1000;
  #endif
  
  	/* Initialize the pre-computed randomized freelist if slab is up */
  	if (slab_state >= UP) {
  		if (init_cache_random_seq(s))
  			goto error;
  	}
  
  	if (!init_kmem_cache_nodes(s))
  		goto error;
  
  	if (alloc_kmem_cache_cpus(s))
  		return 0;
  
  	free_kmem_cache_nodes(s);
  error:
  	if (flags & SLAB_PANIC)
  		panic("Cannot create slab %s size=%u realsize=%u order=%u offset=%u flags=%lx\n",
  		      s->name, s->size, s->size,
  		      oo_order(s->oo), s->offset, (unsigned long)flags);
  	return -EINVAL;
  }
  
  static void list_slab_objects(struct kmem_cache *s, struct page *page,
  							const char *text)
  {
  #ifdef CONFIG_SLUB_DEBUG
  	void *addr = page_address(page);
  	void *p;
  	unsigned long *map = kzalloc(BITS_TO_LONGS(page->objects) *
  				     sizeof(long), GFP_ATOMIC);
  	if (!map)
  		return;
  	slab_err(s, page, text, s->name);
  	slab_lock(page);
  
  	get_map(s, page, map);
  	for_each_object(p, s, addr, page->objects) {
  
  		if (!test_bit(slab_index(p, s, addr), map)) {
  			pr_err("INFO: Object 0x%p @offset=%tu\n", p, p - addr);
  			print_tracking(s, p);
  		}
  	}
  	slab_unlock(page);
  	kfree(map);
  #endif
  }
  
  /*
   * Attempt to free all partial slabs on a node.
   * This is called from __kmem_cache_shutdown(). We must take list_lock
   * because sysfs file might still access partial list after the shutdowning.
   */
  static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n)
  {
  	LIST_HEAD(discard);
  	struct page *page, *h;
  
  	BUG_ON(irqs_disabled());
  	spin_lock_irq(&n->list_lock);
  	list_for_each_entry_safe(page, h, &n->partial, lru) {
  		if (!page->inuse) {
  			remove_partial(n, page);
  			list_add(&page->lru, &discard);
  		} else {
  			list_slab_objects(s, page,
  			"Objects remaining in %s on __kmem_cache_shutdown()");
  		}
  	}
  	spin_unlock_irq(&n->list_lock);
  
  	list_for_each_entry_safe(page, h, &discard, lru)
  		discard_slab(s, page);
  }
  
  bool __kmem_cache_empty(struct kmem_cache *s)
  {
  	int node;
  	struct kmem_cache_node *n;
  
  	for_each_kmem_cache_node(s, node, n)
  		if (n->nr_partial || slabs_node(s, node))
  			return false;
  	return true;
  }
  
  /*
   * Release all resources used by a slab cache.
   */
  int __kmem_cache_shutdown(struct kmem_cache *s)
  {
  	int node;
  	struct kmem_cache_node *n;
  
  	flush_all(s);
  	/* Attempt to free all objects */
  	for_each_kmem_cache_node(s, node, n) {
  		free_partial(s, n);
  		if (n->nr_partial || slabs_node(s, node))
  			return 1;
  	}
  	sysfs_slab_remove(s);
  	return 0;
  }
  
  /********************************************************************
   *		Kmalloc subsystem
   *******************************************************************/
  
  static int __init setup_slub_min_order(char *str)
  {
  	get_option(&str, (int *)&slub_min_order);
  
  	return 1;
  }
  
  __setup("slub_min_order=", setup_slub_min_order);
  
  static int __init setup_slub_max_order(char *str)
  {
  	get_option(&str, (int *)&slub_max_order);
  	slub_max_order = min(slub_max_order, (unsigned int)MAX_ORDER - 1);
  
  	return 1;
  }
  
  __setup("slub_max_order=", setup_slub_max_order);
  
  static int __init setup_slub_min_objects(char *str)
  {
  	get_option(&str, (int *)&slub_min_objects);
  
  	return 1;
  }
  
  __setup("slub_min_objects=", setup_slub_min_objects);
  
  void *__kmalloc(size_t size, gfp_t flags)
  {
  	struct kmem_cache *s;
  	void *ret;
  
  	if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
  		return kmalloc_large(size, flags);
  
  	s = kmalloc_slab(size, flags);
  
  	if (unlikely(ZERO_OR_NULL_PTR(s)))
  		return s;
  
  	ret = slab_alloc(s, flags, _RET_IP_);
  
  	trace_kmalloc(_RET_IP_, ret, size, s->size, flags);
  
  	kasan_kmalloc(s, ret, size, flags);
  
  	return ret;
  }
  EXPORT_SYMBOL(__kmalloc);
  
  #ifdef CONFIG_NUMA
  static void *kmalloc_large_node(size_t size, gfp_t flags, int node)
  {
  	struct page *page;
  	void *ptr = NULL;
  
  	flags |= __GFP_COMP;
  	page = alloc_pages_node(node, flags, get_order(size));
  	if (page)
  		ptr = page_address(page);
  
  	kmalloc_large_node_hook(ptr, size, flags);
  	return ptr;
  }
  
  void *__kmalloc_node(size_t size, gfp_t flags, int node)
  {
  	struct kmem_cache *s;
  	void *ret;
  
  	if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
  		ret = kmalloc_large_node(size, flags, node);
  
  		trace_kmalloc_node(_RET_IP_, ret,
  				   size, PAGE_SIZE << get_order(size),
  				   flags, node);
  
  		return ret;
  	}
  
  	s = kmalloc_slab(size, flags);
  
  	if (unlikely(ZERO_OR_NULL_PTR(s)))
  		return s;
  
  	ret = slab_alloc_node(s, flags, node, _RET_IP_);
  
  	trace_kmalloc_node(_RET_IP_, ret, size, s->size, flags, node);
  
  	kasan_kmalloc(s, ret, size, flags);
  
  	return ret;
  }
  EXPORT_SYMBOL(__kmalloc_node);
  #endif
  
  #ifdef CONFIG_HARDENED_USERCOPY
  /*
   * Rejects incorrectly sized objects and objects that are to be copied
   * to/from userspace but do not fall entirely within the containing slab
   * cache's usercopy region.
   *
   * Returns NULL if check passes, otherwise const char * to name of cache
   * to indicate an error.
   */
  void __check_heap_object(const void *ptr, unsigned long n, struct page *page,
  			 bool to_user)
  {
  	struct kmem_cache *s;
  	unsigned int offset;
  	size_t object_size;
  
  	/* Find object and usable object size. */
  	s = page->slab_cache;
  
  	/* Reject impossible pointers. */
  	if (ptr < page_address(page))
  		usercopy_abort("SLUB object not in SLUB page?!", NULL,
  			       to_user, 0, n);
  
  	/* Find offset within object. */
  	offset = (ptr - page_address(page)) % s->size;
  
  	/* Adjust for redzone and reject if within the redzone. */
  	if (kmem_cache_debug(s) && s->flags & SLAB_RED_ZONE) {
  		if (offset < s->red_left_pad)
  			usercopy_abort("SLUB object in left red zone",
  				       s->name, to_user, offset, n);
  		offset -= s->red_left_pad;
  	}
  
  	/* Allow address range falling entirely within usercopy region. */
  	if (offset >= s->useroffset &&
  	    offset - s->useroffset <= s->usersize &&
  	    n <= s->useroffset - offset + s->usersize)
  		return;
  
  	/*
  	 * If the copy is still within the allocated object, produce
  	 * a warning instead of rejecting the copy. This is intended
  	 * to be a temporary method to find any missing usercopy
  	 * whitelists.
  	 */
  	object_size = slab_ksize(s);
  	if (usercopy_fallback &&
  	    offset <= object_size && n <= object_size - offset) {
  		usercopy_warn("SLUB object", s->name, to_user, offset, n);
  		return;
  	}
  
  	usercopy_abort("SLUB object", s->name, to_user, offset, n);
  }
  #endif /* CONFIG_HARDENED_USERCOPY */
  
  static size_t __ksize(const void *object)
  {
  	struct page *page;
  
  	if (unlikely(object == ZERO_SIZE_PTR))
  		return 0;
  
  	page = virt_to_head_page(object);
  
  	if (unlikely(!PageSlab(page))) {
  		WARN_ON(!PageCompound(page));
  		return PAGE_SIZE << compound_order(page);
  	}
  
  	return slab_ksize(page->slab_cache);
  }
  
  size_t ksize(const void *object)
  {
  	size_t size = __ksize(object);
  	/* We assume that ksize callers could use whole allocated area,
  	 * so we need to unpoison this area.
  	 */
  	kasan_unpoison_shadow(object, size);
  	return size;
  }
  EXPORT_SYMBOL(ksize);
  
  void kfree(const void *x)
  {
  	struct page *page;
  	void *object = (void *)x;
  
  	trace_kfree(_RET_IP_, x);
  
  	if (unlikely(ZERO_OR_NULL_PTR(x)))
  		return;
  
  	page = virt_to_head_page(x);
  	if (unlikely(!PageSlab(page))) {
  		BUG_ON(!PageCompound(page));
  		kfree_hook(object);
  		__free_pages(page, compound_order(page));
  		return;
  	}
  	slab_free(page->slab_cache, page, object, NULL, 1, _RET_IP_);
  }
  EXPORT_SYMBOL(kfree);
  
  #define SHRINK_PROMOTE_MAX 32
  
  /*
   * kmem_cache_shrink discards empty slabs and promotes the slabs filled
   * up most to the head of the partial lists. New allocations will then
   * fill those up and thus they can be removed from the partial lists.
   *
   * The slabs with the least items are placed last. This results in them
   * being allocated from last increasing the chance that the last objects
   * are freed in them.
   */
  int __kmem_cache_shrink(struct kmem_cache *s)
  {
  	int node;
  	int i;
  	struct kmem_cache_node *n;
  	struct page *page;
  	struct page *t;
  	struct list_head discard;
  	struct list_head promote[SHRINK_PROMOTE_MAX];
  	unsigned long flags;
  	int ret = 0;
  
  	flush_all(s);
  	for_each_kmem_cache_node(s, node, n) {
  		INIT_LIST_HEAD(&discard);
  		for (i = 0; i < SHRINK_PROMOTE_MAX; i++)
  			INIT_LIST_HEAD(promote + i);
  
  		spin_lock_irqsave(&n->list_lock, flags);
  
  		/*
  		 * Build lists of slabs to discard or promote.
  		 *
  		 * Note that concurrent frees may occur while we hold the
  		 * list_lock. page->inuse here is the upper limit.
  		 */
  		list_for_each_entry_safe(page, t, &n->partial, lru) {
  			int free = page->objects - page->inuse;
  
  			/* Do not reread page->inuse */
  			barrier();
  
  			/* We do not keep full slabs on the list */
  			BUG_ON(free <= 0);
  
  			if (free == page->objects) {
  				list_move(&page->lru, &discard);
  				n->nr_partial--;
  			} else if (free <= SHRINK_PROMOTE_MAX)
  				list_move(&page->lru, promote + free - 1);
  		}
  
  		/*
  		 * Promote the slabs filled up most to the head of the
  		 * partial list.
  		 */
  		for (i = SHRINK_PROMOTE_MAX - 1; i >= 0; i--)
  			list_splice(promote + i, &n->partial);
  
  		spin_unlock_irqrestore(&n->list_lock, flags);
  
  		/* Release empty slabs */
  		list_for_each_entry_safe(page, t, &discard, lru)
  			discard_slab(s, page);
  
  		if (slabs_node(s, node))
  			ret = 1;
  	}
  
  	return ret;
  }
  
  #ifdef CONFIG_MEMCG
  static void kmemcg_cache_deact_after_rcu(struct kmem_cache *s)
  {
  	/*
  	 * Called with all the locks held after a sched RCU grace period.
  	 * Even if @s becomes empty after shrinking, we can't know that @s
  	 * doesn't have allocations already in-flight and thus can't
  	 * destroy @s until the associated memcg is released.
  	 *
  	 * However, let's remove the sysfs files for empty caches here.
  	 * Each cache has a lot of interface files which aren't
  	 * particularly useful for empty draining caches; otherwise, we can
  	 * easily end up with millions of unnecessary sysfs files on
  	 * systems which have a lot of memory and transient cgroups.
  	 */
  	if (!__kmem_cache_shrink(s))
  		sysfs_slab_remove(s);
  }
  
  void __kmemcg_cache_deactivate(struct kmem_cache *s)
  {
  	/*
  	 * Disable empty slabs caching. Used to avoid pinning offline
  	 * memory cgroups by kmem pages that can be freed.
  	 */
  	slub_set_cpu_partial(s, 0);
  	s->min_partial = 0;
  
  	/*
  	 * s->cpu_partial is checked locklessly (see put_cpu_partial), so
  	 * we have to make sure the change is visible before shrinking.
  	 */
  	slab_deactivate_memcg_cache_rcu_sched(s, kmemcg_cache_deact_after_rcu);
  }
  #endif
  
  static int slab_mem_going_offline_callback(void *arg)
  {
  	struct kmem_cache *s;
  
  	mutex_lock(&slab_mutex);
  	list_for_each_entry(s, &slab_caches, list)
  		__kmem_cache_shrink(s);
  	mutex_unlock(&slab_mutex);
  
  	return 0;
  }
  
  static void slab_mem_offline_callback(void *arg)
  {
  	struct kmem_cache_node *n;
  	struct kmem_cache *s;
  	struct memory_notify *marg = arg;
  	int offline_node;
  
  	offline_node = marg->status_change_nid_normal;
  
  	/*
  	 * If the node still has available memory. we need kmem_cache_node
  	 * for it yet.
  	 */
  	if (offline_node < 0)
  		return;
  
  	mutex_lock(&slab_mutex);
  	list_for_each_entry(s, &slab_caches, list) {
  		n = get_node(s, offline_node);
  		if (n) {
  			/*
  			 * if n->nr_slabs > 0, slabs still exist on the node
  			 * that is going down. We were unable to free them,
  			 * and offline_pages() function shouldn't call this
  			 * callback. So, we must fail.
  			 */
  			BUG_ON(slabs_node(s, offline_node));
  
  			s->node[offline_node] = NULL;
  			kmem_cache_free(kmem_cache_node, n);
  		}
  	}
  	mutex_unlock(&slab_mutex);
  }
  
  static int slab_mem_going_online_callback(void *arg)
  {
  	struct kmem_cache_node *n;
  	struct kmem_cache *s;
  	struct memory_notify *marg = arg;
  	int nid = marg->status_change_nid_normal;
  	int ret = 0;
  
  	/*
  	 * If the node's memory is already available, then kmem_cache_node is
  	 * already created. Nothing to do.
  	 */
  	if (nid < 0)
  		return 0;
  
  	/*
  	 * We are bringing a node online. No memory is available yet. We must
  	 * allocate a kmem_cache_node structure in order to bring the node
  	 * online.
  	 */
  	mutex_lock(&slab_mutex);
  	list_for_each_entry(s, &slab_caches, list) {
  		/*
  		 * XXX: kmem_cache_alloc_node will fallback to other nodes
  		 *      since memory is not yet available from the node that
  		 *      is brought up.
  		 */
  		n = kmem_cache_alloc(kmem_cache_node, GFP_KERNEL);
  		if (!n) {
  			ret = -ENOMEM;
  			goto out;
  		}
  		init_kmem_cache_node(n);
  		s->node[nid] = n;
  	}
  out:
  	mutex_unlock(&slab_mutex);
  	return ret;
  }
  
  static int slab_memory_callback(struct notifier_block *self,
  				unsigned long action, void *arg)
  {
  	int ret = 0;
  
  	switch (action) {
  	case MEM_GOING_ONLINE:
  		ret = slab_mem_going_online_callback(arg);
  		break;
  	case MEM_GOING_OFFLINE:
  		ret = slab_mem_going_offline_callback(arg);
  		break;
  	case MEM_OFFLINE:
  	case MEM_CANCEL_ONLINE:
  		slab_mem_offline_callback(arg);
  		break;
  	case MEM_ONLINE:
  	case MEM_CANCEL_OFFLINE:
  		break;
  	}
  	if (ret)
  		ret = notifier_from_errno(ret);
  	else
  		ret = NOTIFY_OK;
  	return ret;
  }
  
  static struct notifier_block slab_memory_callback_nb = {
  	.notifier_call = slab_memory_callback,
  	.priority = SLAB_CALLBACK_PRI,
  };
  
  /********************************************************************
   *			Basic setup of slabs
   *******************************************************************/
  
  /*
   * Used for early kmem_cache structures that were allocated using
   * the page allocator. Allocate them properly then fix up the pointers
   * that may be pointing to the wrong kmem_cache structure.
   */
  
  static struct kmem_cache * __init bootstrap(struct kmem_cache *static_cache)
  {
  	int node;
  	struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
  	struct kmem_cache_node *n;
  
  	memcpy(s, static_cache, kmem_cache->object_size);
  
  	/*
  	 * This runs very early, and only the boot processor is supposed to be
  	 * up.  Even if it weren't true, IRQs are not up so we couldn't fire
  	 * IPIs around.
  	 */
  	__flush_cpu_slab(s, smp_processor_id());
  	for_each_kmem_cache_node(s, node, n) {
  		struct page *p;
  
  		list_for_each_entry(p, &n->partial, lru)
  			p->slab_cache = s;
  
  #ifdef CONFIG_SLUB_DEBUG
  		list_for_each_entry(p, &n->full, lru)
  			p->slab_cache = s;
  #endif
  	}
  	slab_init_memcg_params(s);
  	list_add(&s->list, &slab_caches);
  	memcg_link_cache(s);
  	return s;
  }
  
  void __init kmem_cache_init(void)
  {
  	static __initdata struct kmem_cache boot_kmem_cache,
  		boot_kmem_cache_node;
  
  	if (debug_guardpage_minorder())
  		slub_max_order = 0;
  
  	kmem_cache_node = &boot_kmem_cache_node;
  	kmem_cache = &boot_kmem_cache;
  
  	create_boot_cache(kmem_cache_node, "kmem_cache_node",
  		sizeof(struct kmem_cache_node), SLAB_HWCACHE_ALIGN, 0, 0);
  
  	register_hotmemory_notifier(&slab_memory_callback_nb);
  
  	/* Able to allocate the per node structures */
  	slab_state = PARTIAL;
  
  	create_boot_cache(kmem_cache, "kmem_cache",
  			offsetof(struct kmem_cache, node) +
  				nr_node_ids * sizeof(struct kmem_cache_node *),
  		       SLAB_HWCACHE_ALIGN, 0, 0);
  
  	kmem_cache = bootstrap(&boot_kmem_cache);
  
  	/*
  	 * Allocate kmem_cache_node properly from the kmem_cache slab.
  	 * kmem_cache_node is separately allocated so no need to
  	 * update any list pointers.
  	 */
  	kmem_cache_node = bootstrap(&boot_kmem_cache_node);
  
  	/* Now we can use the kmem_cache to allocate kmalloc slabs */
  	setup_kmalloc_cache_index_table();
  	create_kmalloc_caches(0);
  
  	/* Setup random freelists for each cache */
  	init_freelist_randomization();
  
  	cpuhp_setup_state_nocalls(CPUHP_SLUB_DEAD, "slub:dead", NULL,
  				  slub_cpu_dead);
  
  	pr_info("SLUB: HWalign=%d, Order=%u-%u, MinObjects=%u, CPUs=%u, Nodes=%d\n",
  		cache_line_size(),
  		slub_min_order, slub_max_order, slub_min_objects,
  		nr_cpu_ids, nr_node_ids);
  }
  
  void __init kmem_cache_init_late(void)
  {
  }
  
  struct kmem_cache *
  __kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
  		   slab_flags_t flags, void (*ctor)(void *))
  {
  	struct kmem_cache *s, *c;
  
  	s = find_mergeable(size, align, flags, name, ctor);
  	if (s) {
  		s->refcount++;
  
  		/*
  		 * Adjust the object sizes so that we clear
  		 * the complete object on kzalloc.
  		 */
  		s->object_size = max(s->object_size, size);
  		s->inuse = max(s->inuse, ALIGN(size, sizeof(void *)));
  
  		for_each_memcg_cache(c, s) {
  			c->object_size = s->object_size;
  			c->inuse = max(c->inuse, ALIGN(size, sizeof(void *)));
  		}
  
  		if (sysfs_slab_alias(s, name)) {
  			s->refcount--;
  			s = NULL;
  		}
  	}
  
  	return s;
  }
  
  int __kmem_cache_create(struct kmem_cache *s, slab_flags_t flags)
  {
  	int err;
  
  	err = kmem_cache_open(s, flags);
  	if (err)
  		return err;
  
  	/* Mutex is not taken during early boot */
  	if (slab_state <= UP)
  		return 0;
  
  	memcg_propagate_slab_attrs(s);
  	err = sysfs_slab_add(s);
  	if (err)
  		__kmem_cache_release(s);
  
  	return err;
  }
  
  void *__kmalloc_track_caller(size_t size, gfp_t gfpflags, unsigned long caller)
  {
  	struct kmem_cache *s;
  	void *ret;
  
  	if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
  		return kmalloc_large(size, gfpflags);
  
  	s = kmalloc_slab(size, gfpflags);
  
  	if (unlikely(ZERO_OR_NULL_PTR(s)))
  		return s;
  
  	ret = slab_alloc(s, gfpflags, caller);
  
  	/* Honor the call site pointer we received. */
  	trace_kmalloc(caller, ret, size, s->size, gfpflags);
  
  	return ret;
  }
  
  #ifdef CONFIG_NUMA
  void *__kmalloc_node_track_caller(size_t size, gfp_t gfpflags,
  					int node, unsigned long caller)
  {
  	struct kmem_cache *s;
  	void *ret;
  
  	if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
  		ret = kmalloc_large_node(size, gfpflags, node);
  
  		trace_kmalloc_node(caller, ret,
  				   size, PAGE_SIZE << get_order(size),
  				   gfpflags, node);
  
  		return ret;
  	}
  
  	s = kmalloc_slab(size, gfpflags);
  
  	if (unlikely(ZERO_OR_NULL_PTR(s)))
  		return s;
  
  	ret = slab_alloc_node(s, gfpflags, node, caller);
  
  	/* Honor the call site pointer we received. */
  	trace_kmalloc_node(caller, ret, size, s->size, gfpflags, node);
  
  	return ret;
  }
  #endif
  
  #ifdef CONFIG_SYSFS
  static int count_inuse(struct page *page)
  {
  	return page->inuse;
  }
  
  static int count_total(struct page *page)
  {
  	return page->objects;
  }
  #endif
  
  #ifdef CONFIG_SLUB_DEBUG
  static int validate_slab(struct kmem_cache *s, struct page *page,
  						unsigned long *map)
  {
  	void *p;
  	void *addr = page_address(page);
  
  	if (!check_slab(s, page) ||
  			!on_freelist(s, page, NULL))
  		return 0;
  
  	/* Now we know that a valid freelist exists */
  	bitmap_zero(map, page->objects);
  
  	get_map(s, page, map);
  	for_each_object(p, s, addr, page->objects) {
  		if (test_bit(slab_index(p, s, addr), map))
  			if (!check_object(s, page, p, SLUB_RED_INACTIVE))
  				return 0;
  	}
  
  	for_each_object(p, s, addr, page->objects)
  		if (!test_bit(slab_index(p, s, addr), map))
  			if (!check_object(s, page, p, SLUB_RED_ACTIVE))
  				return 0;
  	return 1;
  }
  
  static void validate_slab_slab(struct kmem_cache *s, struct page *page,
  						unsigned long *map)
  {
  	slab_lock(page);
  	validate_slab(s, page, map);
  	slab_unlock(page);
  }
  
  static int validate_slab_node(struct kmem_cache *s,
  		struct kmem_cache_node *n, unsigned long *map)
  {
  	unsigned long count = 0;
  	struct page *page;
  	unsigned long flags;
  
  	spin_lock_irqsave(&n->list_lock, flags);
  
  	list_for_each_entry(page, &n->partial, lru) {
  		validate_slab_slab(s, page, map);
  		count++;
  	}
  	if (count != n->nr_partial)
  		pr_err("SLUB %s: %ld partial slabs counted but counter=%ld\n",
  		       s->name, count, n->nr_partial);
  
  	if (!(s->flags & SLAB_STORE_USER))
  		goto out;
  
  	list_for_each_entry(page, &n->full, lru) {
  		validate_slab_slab(s, page, map);
  		count++;
  	}
  	if (count != atomic_long_read(&n->nr_slabs))
  		pr_err("SLUB: %s %ld slabs counted but counter=%ld\n",
  		       s->name, count, atomic_long_read(&n->nr_slabs));
  
  out:
  	spin_unlock_irqrestore(&n->list_lock, flags);
  	return count;
  }
  
  static long validate_slab_cache(struct kmem_cache *s)
  {
  	int node;
  	unsigned long count = 0;
  	unsigned long *map = kmalloc(BITS_TO_LONGS(oo_objects(s->max)) *
  				sizeof(unsigned long), GFP_KERNEL);
  	struct kmem_cache_node *n;
  
  	if (!map)
  		return -ENOMEM;
  
  	flush_all(s);
  	for_each_kmem_cache_node(s, node, n)
  		count += validate_slab_node(s, n, map);
  	kfree(map);
  	return count;
  }
  /*
   * Generate lists of code addresses where slabcache objects are allocated
   * and freed.
   */
  
  struct location {
  	unsigned long count;
  	unsigned long addr;
  	long long sum_time;
  	long min_time;
  	long max_time;
  	long min_pid;
  	long max_pid;
  	DECLARE_BITMAP(cpus, NR_CPUS);
  	nodemask_t nodes;
  };
  
  struct loc_track {
  	unsigned long max;
  	unsigned long count;
  	struct location *loc;
  };
  
  static void free_loc_track(struct loc_track *t)
  {
  	if (t->max)
  		free_pages((unsigned long)t->loc,
  			get_order(sizeof(struct location) * t->max));
  }
  
  static int alloc_loc_track(struct loc_track *t, unsigned long max, gfp_t flags)
  {
  	struct location *l;
  	int order;
  
  	order = get_order(sizeof(struct location) * max);
  
  	l = (void *)__get_free_pages(flags, order);
  	if (!l)
  		return 0;
  
  	if (t->count) {
  		memcpy(l, t->loc, sizeof(struct location) * t->count);
  		free_loc_track(t);
  	}
  	t->max = max;
  	t->loc = l;
  	return 1;
  }
  
  static int add_location(struct loc_track *t, struct kmem_cache *s,
  				const struct track *track)
  {
  	long start, end, pos;
  	struct location *l;
  	unsigned long caddr;
  	unsigned long age = jiffies - track->when;
  
  	start = -1;
  	end = t->count;
  
  	for ( ; ; ) {
  		pos = start + (end - start + 1) / 2;
  
  		/*
  		 * There is nothing at "end". If we end up there
  		 * we need to add something to before end.
  		 */
  		if (pos == end)
  			break;
  
  		caddr = t->loc[pos].addr;
  		if (track->addr == caddr) {
  
  			l = &t->loc[pos];
  			l->count++;
  			if (track->when) {
  				l->sum_time += age;
  				if (age < l->min_time)
  					l->min_time = age;
  				if (age > l->max_time)
  					l->max_time = age;
  
  				if (track->pid < l->min_pid)
  					l->min_pid = track->pid;
  				if (track->pid > l->max_pid)
  					l->max_pid = track->pid;
  
  				cpumask_set_cpu(track->cpu,
  						to_cpumask(l->cpus));
  			}
  			node_set(page_to_nid(virt_to_page(track)), l->nodes);
  			return 1;
  		}
  
  		if (track->addr < caddr)
  			end = pos;
  		else
  			start = pos;
  	}
  
  	/*
  	 * Not found. Insert new tracking element.
  	 */
  	if (t->count >= t->max && !alloc_loc_track(t, 2 * t->max, GFP_ATOMIC))
  		return 0;
  
  	l = t->loc + pos;
  	if (pos < t->count)
  		memmove(l + 1, l,
  			(t->count - pos) * sizeof(struct location));
  	t->count++;
  	l->count = 1;
  	l->addr = track->addr;
  	l->sum_time = age;
  	l->min_time = age;
  	l->max_time = age;
  	l->min_pid = track->pid;
  	l->max_pid = track->pid;
  	cpumask_clear(to_cpumask(l->cpus));
  	cpumask_set_cpu(track->cpu, to_cpumask(l->cpus));
  	nodes_clear(l->nodes);
  	node_set(page_to_nid(virt_to_page(track)), l->nodes);
  	return 1;
  }
  
  static void process_slab(struct loc_track *t, struct kmem_cache *s,
  		struct page *page, enum track_item alloc,
  		unsigned long *map)
  {
  	void *addr = page_address(page);
  	void *p;
  
  	bitmap_zero(map, page->objects);
  	get_map(s, page, map);
  
  	for_each_object(p, s, addr, page->objects)
  		if (!test_bit(slab_index(p, s, addr), map))
  			add_location(t, s, get_track(s, p, alloc));
  }
  
  static int list_locations(struct kmem_cache *s, char *buf,
  					enum track_item alloc)
  {
  	int len = 0;
  	unsigned long i;
  	struct loc_track t = { 0, 0, NULL };
  	int node;
  	unsigned long *map = kmalloc(BITS_TO_LONGS(oo_objects(s->max)) *
  				     sizeof(unsigned long), GFP_KERNEL);
  	struct kmem_cache_node *n;
  
  	if (!map || !alloc_loc_track(&t, PAGE_SIZE / sizeof(struct location),
  				     GFP_KERNEL)) {
  		kfree(map);
  		return sprintf(buf, "Out of memory\n");
  	}
  	/* Push back cpu slabs */
  	flush_all(s);
  
  	for_each_kmem_cache_node(s, node, n) {
  		unsigned long flags;
  		struct page *page;
  
  		if (!atomic_long_read(&n->nr_slabs))
  			continue;
  
  		spin_lock_irqsave(&n->list_lock, flags);
  		list_for_each_entry(page, &n->partial, lru)
  			process_slab(&t, s, page, alloc, map);
  		list_for_each_entry(page, &n->full, lru)
  			process_slab(&t, s, page, alloc, map);
  		spin_unlock_irqrestore(&n->list_lock, flags);
  	}
  
  	for (i = 0; i < t.count; i++) {
  		struct location *l = &t.loc[i];
  
  		if (len > PAGE_SIZE - KSYM_SYMBOL_LEN - 100)
  			break;
  		len += sprintf(buf + len, "%7ld ", l->count);
  
  		if (l->addr)
  			len += sprintf(buf + len, "%pS", (void *)l->addr);
  		else
  			len += sprintf(buf + len, "<not-available>");
  
  		if (l->sum_time != l->min_time) {
  			len += sprintf(buf + len, " age=%ld/%ld/%ld",
  				l->min_time,
  				(long)div_u64(l->sum_time, l->count),
  				l->max_time);
  		} else
  			len += sprintf(buf + len, " age=%ld",
  				l->min_time);
  
  		if (l->min_pid != l->max_pid)
  			len += sprintf(buf + len, " pid=%ld-%ld",
  				l->min_pid, l->max_pid);
  		else
  			len += sprintf(buf + len, " pid=%ld",
  				l->min_pid);
  
  		if (num_online_cpus() > 1 &&
  				!cpumask_empty(to_cpumask(l->cpus)) &&
  				len < PAGE_SIZE - 60)
  			len += scnprintf(buf + len, PAGE_SIZE - len - 50,
  					 " cpus=%*pbl",
  					 cpumask_pr_args(to_cpumask(l->cpus)));
  
  		if (nr_online_nodes > 1 && !nodes_empty(l->nodes) &&
  				len < PAGE_SIZE - 60)
  			len += scnprintf(buf + len, PAGE_SIZE - len - 50,
  					 " nodes=%*pbl",
  					 nodemask_pr_args(&l->nodes));
  
  		len += sprintf(buf + len, "\n");
  	}
  
  	free_loc_track(&t);
  	kfree(map);
  	if (!t.count)
  		len += sprintf(buf, "No data\n");
  	return len;
  }
  #endif
  
  #ifdef SLUB_RESILIENCY_TEST
  static void __init resiliency_test(void)
  {
  	u8 *p;
  
  	BUILD_BUG_ON(KMALLOC_MIN_SIZE > 16 || KMALLOC_SHIFT_HIGH < 10);
  
  	pr_err("SLUB resiliency testing\n");
  	pr_err("-----------------------\n");
  	pr_err("A. Corruption after allocation\n");
  
  	p = kzalloc(16, GFP_KERNEL);
  	p[16] = 0x12;
  	pr_err("\n1. kmalloc-16: Clobber Redzone/next pointer 0x12->0x%p\n\n",
  	       p + 16);
  
  	validate_slab_cache(kmalloc_caches[4]);
  
  	/* Hmmm... The next two are dangerous */
  	p = kzalloc(32, GFP_KERNEL);
  	p[32 + sizeof(void *)] = 0x34;
  	pr_err("\n2. kmalloc-32: Clobber next pointer/next slab 0x34 -> -0x%p\n",
  	       p);
  	pr_err("If allocated object is overwritten then not detectable\n\n");
  
  	validate_slab_cache(kmalloc_caches[5]);
  	p = kzalloc(64, GFP_KERNEL);
  	p += 64 + (get_cycles() & 0xff) * sizeof(void *);
  	*p = 0x56;
  	pr_err("\n3. kmalloc-64: corrupting random byte 0x56->0x%p\n",
  	       p);
  	pr_err("If allocated object is overwritten then not detectable\n\n");
  	validate_slab_cache(kmalloc_caches[6]);
  
  	pr_err("\nB. Corruption after free\n");
  	p = kzalloc(128, GFP_KERNEL);
  	kfree(p);
  	*p = 0x78;
  	pr_err("1. kmalloc-128: Clobber first word 0x78->0x%p\n\n", p);
  	validate_slab_cache(kmalloc_caches[7]);
  
  	p = kzalloc(256, GFP_KERNEL);
  	kfree(p);
  	p[50] = 0x9a;
  	pr_err("\n2. kmalloc-256: Clobber 50th byte 0x9a->0x%p\n\n", p);
  	validate_slab_cache(kmalloc_caches[8]);
  
  	p = kzalloc(512, GFP_KERNEL);
  	kfree(p);
  	p[512] = 0xab;
  	pr_err("\n3. kmalloc-512: Clobber redzone 0xab->0x%p\n\n", p);
  	validate_slab_cache(kmalloc_caches[9]);
  }
  #else
  #ifdef CONFIG_SYSFS
  static void resiliency_test(void) {};
  #endif
  #endif
  
  #ifdef CONFIG_SYSFS
  enum slab_stat_type {
  	SL_ALL,			/* All slabs */
  	SL_PARTIAL,		/* Only partially allocated slabs */
  	SL_CPU,			/* Only slabs used for cpu caches */
  	SL_OBJECTS,		/* Determine allocated objects not slabs */
  	SL_TOTAL		/* Determine object capacity not slabs */
  };
  
  #define SO_ALL		(1 << SL_ALL)
  #define SO_PARTIAL	(1 << SL_PARTIAL)
  #define SO_CPU		(1 << SL_CPU)
  #define SO_OBJECTS	(1 << SL_OBJECTS)
  #define SO_TOTAL	(1 << SL_TOTAL)
  
  #ifdef CONFIG_MEMCG
  static bool memcg_sysfs_enabled = IS_ENABLED(CONFIG_SLUB_MEMCG_SYSFS_ON);
  
  static int __init setup_slub_memcg_sysfs(char *str)
  {
  	int v;
  
  	if (get_option(&str, &v) > 0)
  		memcg_sysfs_enabled = v;
  
  	return 1;
  }
  
  __setup("slub_memcg_sysfs=", setup_slub_memcg_sysfs);
  #endif
  
  static ssize_t show_slab_objects(struct kmem_cache *s,
  			    char *buf, unsigned long flags)
  {
  	unsigned long total = 0;
  	int node;
  	int x;
  	unsigned long *nodes;
  
  	nodes = kzalloc(sizeof(unsigned long) * nr_node_ids, GFP_KERNEL);
  	if (!nodes)
  		return -ENOMEM;
  
  	if (flags & SO_CPU) {
  		int cpu;
  
  		for_each_possible_cpu(cpu) {
  			struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab,
  							       cpu);
  			int node;
  			struct page *page;
  
  			page = READ_ONCE(c->page);
  			if (!page)
  				continue;
  
  			node = page_to_nid(page);
  			if (flags & SO_TOTAL)
  				x = page->objects;
  			else if (flags & SO_OBJECTS)
  				x = page->inuse;
  			else
  				x = 1;
  
  			total += x;
  			nodes[node] += x;
  
  			page = slub_percpu_partial_read_once(c);
  			if (page) {
  				node = page_to_nid(page);
  				if (flags & SO_TOTAL)
  					WARN_ON_ONCE(1);
  				else if (flags & SO_OBJECTS)
  					WARN_ON_ONCE(1);
  				else
  					x = page->pages;
  				total += x;
  				nodes[node] += x;
  			}
  		}
  	}
  
  	get_online_mems();
  #ifdef CONFIG_SLUB_DEBUG
  	if (flags & SO_ALL) {
  		struct kmem_cache_node *n;
  
  		for_each_kmem_cache_node(s, node, n) {
  
  			if (flags & SO_TOTAL)
  				x = atomic_long_read(&n->total_objects);
  			else if (flags & SO_OBJECTS)
  				x = atomic_long_read(&n->total_objects) -
  					count_partial(n, count_free);
  			else
  				x = atomic_long_read(&n->nr_slabs);
  			total += x;
  			nodes[node] += x;
  		}
  
  	} else
  #endif
  	if (flags & SO_PARTIAL) {
  		struct kmem_cache_node *n;
  
  		for_each_kmem_cache_node(s, node, n) {
  			if (flags & SO_TOTAL)
  				x = count_partial(n, count_total);
  			else if (flags & SO_OBJECTS)
  				x = count_partial(n, count_inuse);
  			else
  				x = n->nr_partial;
  			total += x;
  			nodes[node] += x;
  		}
  	}
  	x = sprintf(buf, "%lu", total);
  #ifdef CONFIG_NUMA
  	for (node = 0; node < nr_node_ids; node++)
  		if (nodes[node])
  			x += sprintf(buf + x, " N%d=%lu",
  					node, nodes[node]);
  #endif
  	put_online_mems();
  	kfree(nodes);
  	return x + sprintf(buf + x, "\n");
  }
  
  #ifdef CONFIG_SLUB_DEBUG
  static int any_slab_objects(struct kmem_cache *s)
  {
  	int node;
  	struct kmem_cache_node *n;
  
  	for_each_kmem_cache_node(s, node, n)
  		if (atomic_long_read(&n->total_objects))
  			return 1;
  
  	return 0;
  }
  #endif
  
  #define to_slab_attr(n) container_of(n, struct slab_attribute, attr)
  #define to_slab(n) container_of(n, struct kmem_cache, kobj)
  
  struct slab_attribute {
  	struct attribute attr;
  	ssize_t (*show)(struct kmem_cache *s, char *buf);
  	ssize_t (*store)(struct kmem_cache *s, const char *x, size_t count);
  };
  
  #define SLAB_ATTR_RO(_name) \
  	static struct slab_attribute _name##_attr = \
  	__ATTR(_name, 0400, _name##_show, NULL)
  
  #define SLAB_ATTR(_name) \
  	static struct slab_attribute _name##_attr =  \
  	__ATTR(_name, 0600, _name##_show, _name##_store)
  
  static ssize_t slab_size_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%u\n", s->size);
  }
  SLAB_ATTR_RO(slab_size);
  
  static ssize_t align_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%u\n", s->align);
  }
  SLAB_ATTR_RO(align);
  
  static ssize_t object_size_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%u\n", s->object_size);
  }
  SLAB_ATTR_RO(object_size);
  
  static ssize_t objs_per_slab_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%u\n", oo_objects(s->oo));
  }
  SLAB_ATTR_RO(objs_per_slab);
  
  static ssize_t order_store(struct kmem_cache *s,
  				const char *buf, size_t length)
  {
  	unsigned int order;
  	int err;
  
  	err = kstrtouint(buf, 10, &order);
  	if (err)
  		return err;
  
  	if (order > slub_max_order || order < slub_min_order)
  		return -EINVAL;
  
  	calculate_sizes(s, order);
  	return length;
  }
  
  static ssize_t order_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%u\n", oo_order(s->oo));
  }
  SLAB_ATTR(order);
  
  static ssize_t min_partial_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%lu\n", s->min_partial);
  }
  
  static ssize_t min_partial_store(struct kmem_cache *s, const char *buf,
  				 size_t length)
  {
  	unsigned long min;
  	int err;
  
  	err = kstrtoul(buf, 10, &min);
  	if (err)
  		return err;
  
  	set_min_partial(s, min);
  	return length;
  }
  SLAB_ATTR(min_partial);
  
  static ssize_t cpu_partial_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%u\n", slub_cpu_partial(s));
  }
  
  static ssize_t cpu_partial_store(struct kmem_cache *s, const char *buf,
  				 size_t length)
  {
  	unsigned int objects;
  	int err;
  
  	err = kstrtouint(buf, 10, &objects);
  	if (err)
  		return err;
  	if (objects && !kmem_cache_has_cpu_partial(s))
  		return -EINVAL;
  
  	slub_set_cpu_partial(s, objects);
  	flush_all(s);
  	return length;
  }
  SLAB_ATTR(cpu_partial);
  
  static ssize_t ctor_show(struct kmem_cache *s, char *buf)
  {
  	if (!s->ctor)
  		return 0;
  	return sprintf(buf, "%pS\n", s->ctor);
  }
  SLAB_ATTR_RO(ctor);
  
  static ssize_t aliases_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%d\n", s->refcount < 0 ? 0 : s->refcount - 1);
  }
  SLAB_ATTR_RO(aliases);
  
  static ssize_t partial_show(struct kmem_cache *s, char *buf)
  {
  	return show_slab_objects(s, buf, SO_PARTIAL);
  }
  SLAB_ATTR_RO(partial);
  
  static ssize_t cpu_slabs_show(struct kmem_cache *s, char *buf)
  {
  	return show_slab_objects(s, buf, SO_CPU);
  }
  SLAB_ATTR_RO(cpu_slabs);
  
  static ssize_t objects_show(struct kmem_cache *s, char *buf)
  {
  	return show_slab_objects(s, buf, SO_ALL|SO_OBJECTS);
  }
  SLAB_ATTR_RO(objects);
  
  static ssize_t objects_partial_show(struct kmem_cache *s, char *buf)
  {
  	return show_slab_objects(s, buf, SO_PARTIAL|SO_OBJECTS);
  }
  SLAB_ATTR_RO(objects_partial);
  
  static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
  {
  	int objects = 0;
  	int pages = 0;
  	int cpu;
  	int len;
  
  	for_each_online_cpu(cpu) {
  		struct page *page;
  
  		page = slub_percpu_partial(per_cpu_ptr(s->cpu_slab, cpu));
  
  		if (page) {
  			pages += page->pages;
  			objects += page->pobjects;
  		}
  	}
  
  	len = sprintf(buf, "%d(%d)", objects, pages);
  
  #ifdef CONFIG_SMP
  	for_each_online_cpu(cpu) {
  		struct page *page;
  
  		page = slub_percpu_partial(per_cpu_ptr(s->cpu_slab, cpu));
  
  		if (page && len < PAGE_SIZE - 20)
  			len += sprintf(buf + len, " C%d=%d(%d)", cpu,
  				page->pobjects, page->pages);
  	}
  #endif
  	return len + sprintf(buf + len, "\n");
  }
  SLAB_ATTR_RO(slabs_cpu_partial);
  
  static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%d\n", !!(s->flags & SLAB_RECLAIM_ACCOUNT));
  }
  
  static ssize_t reclaim_account_store(struct kmem_cache *s,
  				const char *buf, size_t length)
  {
  	s->flags &= ~SLAB_RECLAIM_ACCOUNT;
  	if (buf[0] == '1')
  		s->flags |= SLAB_RECLAIM_ACCOUNT;
  	return length;
  }
  SLAB_ATTR(reclaim_account);
  
  static ssize_t hwcache_align_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%d\n", !!(s->flags & SLAB_HWCACHE_ALIGN));
  }
  SLAB_ATTR_RO(hwcache_align);
  
  #ifdef CONFIG_ZONE_DMA
  static ssize_t cache_dma_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%d\n", !!(s->flags & SLAB_CACHE_DMA));
  }
  SLAB_ATTR_RO(cache_dma);
  #endif
  
  static ssize_t usersize_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%u\n", s->usersize);
  }
  SLAB_ATTR_RO(usersize);
  
  static ssize_t destroy_by_rcu_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%d\n", !!(s->flags & SLAB_TYPESAFE_BY_RCU));
  }
  SLAB_ATTR_RO(destroy_by_rcu);
  
  static ssize_t reserved_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%u\n", s->reserved);
  }
  SLAB_ATTR_RO(reserved);
  
  #ifdef CONFIG_SLUB_DEBUG
  static ssize_t slabs_show(struct kmem_cache *s, char *buf)
  {
  	return show_slab_objects(s, buf, SO_ALL);
  }
  SLAB_ATTR_RO(slabs);
  
  static ssize_t total_objects_show(struct kmem_cache *s, char *buf)
  {
  	return show_slab_objects(s, buf, SO_ALL|SO_TOTAL);
  }
  SLAB_ATTR_RO(total_objects);
  
  static ssize_t sanity_checks_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%d\n", !!(s->flags & SLAB_CONSISTENCY_CHECKS));
  }
  
  static ssize_t sanity_checks_store(struct kmem_cache *s,
  				const char *buf, size_t length)
  {
  	s->flags &= ~SLAB_CONSISTENCY_CHECKS;
  	if (buf[0] == '1') {
  		s->flags &= ~__CMPXCHG_DOUBLE;
  		s->flags |= SLAB_CONSISTENCY_CHECKS;
  	}
  	return length;
  }
  SLAB_ATTR(sanity_checks);
  
  static ssize_t trace_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%d\n", !!(s->flags & SLAB_TRACE));
  }
  
  static ssize_t trace_store(struct kmem_cache *s, const char *buf,
  							size_t length)
  {
  	/*
  	 * Tracing a merged cache is going to give confusing results
  	 * as well as cause other issues like converting a mergeable
  	 * cache into an umergeable one.
  	 */
  	if (s->refcount > 1)
  		return -EINVAL;
  
  	s->flags &= ~SLAB_TRACE;
  	if (buf[0] == '1') {
  		s->flags &= ~__CMPXCHG_DOUBLE;
  		s->flags |= SLAB_TRACE;
  	}
  	return length;
  }
  SLAB_ATTR(trace);
  
  static ssize_t red_zone_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%d\n", !!(s->flags & SLAB_RED_ZONE));
  }
  
  static ssize_t red_zone_store(struct kmem_cache *s,
  				const char *buf, size_t length)
  {
  	if (any_slab_objects(s))
  		return -EBUSY;
  
  	s->flags &= ~SLAB_RED_ZONE;
  	if (buf[0] == '1') {
  		s->flags |= SLAB_RED_ZONE;
  	}
  	calculate_sizes(s, -1);
  	return length;
  }
  SLAB_ATTR(red_zone);
  
  static ssize_t poison_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%d\n", !!(s->flags & SLAB_POISON));
  }
  
  static ssize_t poison_store(struct kmem_cache *s,
  				const char *buf, size_t length)
  {
  	if (any_slab_objects(s))
  		return -EBUSY;
  
  	s->flags &= ~SLAB_POISON;
  	if (buf[0] == '1') {
  		s->flags |= SLAB_POISON;
  	}
  	calculate_sizes(s, -1);
  	return length;
  }
  SLAB_ATTR(poison);
  
  static ssize_t store_user_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%d\n", !!(s->flags & SLAB_STORE_USER));
  }
  
  static ssize_t store_user_store(struct kmem_cache *s,
  				const char *buf, size_t length)
  {
  	if (any_slab_objects(s))
  		return -EBUSY;
  
  	s->flags &= ~SLAB_STORE_USER;
  	if (buf[0] == '1') {
  		s->flags &= ~__CMPXCHG_DOUBLE;
  		s->flags |= SLAB_STORE_USER;
  	}
  	calculate_sizes(s, -1);
  	return length;
  }
  SLAB_ATTR(store_user);
  
  static ssize_t validate_show(struct kmem_cache *s, char *buf)
  {
  	return 0;
  }
  
  static ssize_t validate_store(struct kmem_cache *s,
  			const char *buf, size_t length)
  {
  	int ret = -EINVAL;
  
  	if (buf[0] == '1') {
  		ret = validate_slab_cache(s);
  		if (ret >= 0)
  			ret = length;
  	}
  	return ret;
  }
  SLAB_ATTR(validate);
  
  static ssize_t alloc_calls_show(struct kmem_cache *s, char *buf)
  {
  	if (!(s->flags & SLAB_STORE_USER))
  		return -ENOSYS;
  	return list_locations(s, buf, TRACK_ALLOC);
  }
  SLAB_ATTR_RO(alloc_calls);
  
  static ssize_t free_calls_show(struct kmem_cache *s, char *buf)
  {
  	if (!(s->flags & SLAB_STORE_USER))
  		return -ENOSYS;
  	return list_locations(s, buf, TRACK_FREE);
  }
  SLAB_ATTR_RO(free_calls);
  #endif /* CONFIG_SLUB_DEBUG */
  
  #ifdef CONFIG_FAILSLAB
  static ssize_t failslab_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%d\n", !!(s->flags & SLAB_FAILSLAB));
  }
  
  static ssize_t failslab_store(struct kmem_cache *s, const char *buf,
  							size_t length)
  {
  	if (s->refcount > 1)
  		return -EINVAL;
  
  	s->flags &= ~SLAB_FAILSLAB;
  	if (buf[0] == '1')
  		s->flags |= SLAB_FAILSLAB;
  	return length;
  }
  SLAB_ATTR(failslab);
  #endif
  
  static ssize_t shrink_show(struct kmem_cache *s, char *buf)
  {
  	return 0;
  }
  
  static ssize_t shrink_store(struct kmem_cache *s,
  			const char *buf, size_t length)
  {
  	if (buf[0] == '1')
  		kmem_cache_shrink(s);
  	else
  		return -EINVAL;
  	return length;
  }
  SLAB_ATTR(shrink);
  
  #ifdef CONFIG_NUMA
  static ssize_t remote_node_defrag_ratio_show(struct kmem_cache *s, char *buf)
  {
  	return sprintf(buf, "%u\n", s->remote_node_defrag_ratio / 10);
  }
  
  static ssize_t remote_node_defrag_ratio_store(struct kmem_cache *s,
  				const char *buf, size_t length)
  {
  	unsigned int ratio;
  	int err;
  
  	err = kstrtouint(buf, 10, &ratio);
  	if (err)
  		return err;
  	if (ratio > 100)
  		return -ERANGE;
  
  	s->remote_node_defrag_ratio = ratio * 10;
  
  	return length;
  }
  SLAB_ATTR(remote_node_defrag_ratio);
  #endif
  
  #ifdef CONFIG_SLUB_STATS
  static int show_stat(struct kmem_cache *s, char *buf, enum stat_item si)
  {
  	unsigned long sum  = 0;
  	int cpu;
  	int len;
  	int *data = kmalloc(nr_cpu_ids * sizeof(int), GFP_KERNEL);
  
  	if (!data)
  		return -ENOMEM;
  
  	for_each_online_cpu(cpu) {
  		unsigned x = per_cpu_ptr(s->cpu_slab, cpu)->stat[si];
  
  		data[cpu] = x;
  		sum += x;
  	}
  
  	len = sprintf(buf, "%lu", sum);
  
  #ifdef CONFIG_SMP
  	for_each_online_cpu(cpu) {
  		if (data[cpu] && len < PAGE_SIZE - 20)
  			len += sprintf(buf + len, " C%d=%u", cpu, data[cpu]);
  	}
  #endif
  	kfree(data);
  	return len + sprintf(buf + len, "\n");
  }
  
  static void clear_stat(struct kmem_cache *s, enum stat_item si)
  {
  	int cpu;
  
  	for_each_online_cpu(cpu)
  		per_cpu_ptr(s->cpu_slab, cpu)->stat[si] = 0;
  }
  
  #define STAT_ATTR(si, text) 					\
  static ssize_t text##_show(struct kmem_cache *s, char *buf)	\
  {								\
  	return show_stat(s, buf, si);				\
  }								\
  static ssize_t text##_store(struct kmem_cache *s,		\
  				const char *buf, size_t length)	\
  {								\
  	if (buf[0] != '0')					\
  		return -EINVAL;					\
  	clear_stat(s, si);					\
  	return length;						\
  }								\
  SLAB_ATTR(text);						\
  
  STAT_ATTR(ALLOC_FASTPATH, alloc_fastpath);
  STAT_ATTR(ALLOC_SLOWPATH, alloc_slowpath);
  STAT_ATTR(FREE_FASTPATH, free_fastpath);
  STAT_ATTR(FREE_SLOWPATH, free_slowpath);
  STAT_ATTR(FREE_FROZEN, free_frozen);
  STAT_ATTR(FREE_ADD_PARTIAL, free_add_partial);
  STAT_ATTR(FREE_REMOVE_PARTIAL, free_remove_partial);
  STAT_ATTR(ALLOC_FROM_PARTIAL, alloc_from_partial);
  STAT_ATTR(ALLOC_SLAB, alloc_slab);
  STAT_ATTR(ALLOC_REFILL, alloc_refill);
  STAT_ATTR(ALLOC_NODE_MISMATCH, alloc_node_mismatch);
  STAT_ATTR(FREE_SLAB, free_slab);
  STAT_ATTR(CPUSLAB_FLUSH, cpuslab_flush);
  STAT_ATTR(DEACTIVATE_FULL, deactivate_full);
  STAT_ATTR(DEACTIVATE_EMPTY, deactivate_empty);
  STAT_ATTR(DEACTIVATE_TO_HEAD, deactivate_to_head);
  STAT_ATTR(DEACTIVATE_TO_TAIL, deactivate_to_tail);
  STAT_ATTR(DEACTIVATE_REMOTE_FREES, deactivate_remote_frees);
  STAT_ATTR(DEACTIVATE_BYPASS, deactivate_bypass);
  STAT_ATTR(ORDER_FALLBACK, order_fallback);
  STAT_ATTR(CMPXCHG_DOUBLE_CPU_FAIL, cmpxchg_double_cpu_fail);
  STAT_ATTR(CMPXCHG_DOUBLE_FAIL, cmpxchg_double_fail);
  STAT_ATTR(CPU_PARTIAL_ALLOC, cpu_partial_alloc);
  STAT_ATTR(CPU_PARTIAL_FREE, cpu_partial_free);
  STAT_ATTR(CPU_PARTIAL_NODE, cpu_partial_node);
  STAT_ATTR(CPU_PARTIAL_DRAIN, cpu_partial_drain);
  #endif
  
  static struct attribute *slab_attrs[] = {
  	&slab_size_attr.attr,
  	&object_size_attr.attr,
  	&objs_per_slab_attr.attr,
  	&order_attr.attr,
  	&min_partial_attr.attr,
  	&cpu_partial_attr.attr,
  	&objects_attr.attr,
  	&objects_partial_attr.attr,
  	&partial_attr.attr,
  	&cpu_slabs_attr.attr,
  	&ctor_attr.attr,
  	&aliases_attr.attr,
  	&align_attr.attr,
  	&hwcache_align_attr.attr,
  	&reclaim_account_attr.attr,
  	&destroy_by_rcu_attr.attr,
  	&shrink_attr.attr,
  	&reserved_attr.attr,
  	&slabs_cpu_partial_attr.attr,
  #ifdef CONFIG_SLUB_DEBUG
  	&total_objects_attr.attr,
  	&slabs_attr.attr,
  	&sanity_checks_attr.attr,
  	&trace_attr.attr,
  	&red_zone_attr.attr,
  	&poison_attr.attr,
  	&store_user_attr.attr,
  	&validate_attr.attr,
  	&alloc_calls_attr.attr,
  	&free_calls_attr.attr,
  #endif
  #ifdef CONFIG_ZONE_DMA
  	&cache_dma_attr.attr,
  #endif
  #ifdef CONFIG_NUMA
  	&remote_node_defrag_ratio_attr.attr,
  #endif
  #ifdef CONFIG_SLUB_STATS
  	&alloc_fastpath_attr.attr,
  	&alloc_slowpath_attr.attr,
  	&free_fastpath_attr.attr,
  	&free_slowpath_attr.attr,
  	&free_frozen_attr.attr,
  	&free_add_partial_attr.attr,
  	&free_remove_partial_attr.attr,
  	&alloc_from_partial_attr.attr,
  	&alloc_slab_attr.attr,
  	&alloc_refill_attr.attr,
  	&alloc_node_mismatch_attr.attr,
  	&free_slab_attr.attr,
  	&cpuslab_flush_attr.attr,
  	&deactivate_full_attr.attr,
  	&deactivate_empty_attr.attr,
  	&deactivate_to_head_attr.attr,
  	&deactivate_to_tail_attr.attr,
  	&deactivate_remote_frees_attr.attr,
  	&deactivate_bypass_attr.attr,
  	&order_fallback_attr.attr,
  	&cmpxchg_double_fail_attr.attr,
  	&cmpxchg_double_cpu_fail_attr.attr,
  	&cpu_partial_alloc_attr.attr,
  	&cpu_partial_free_attr.attr,
  	&cpu_partial_node_attr.attr,
  	&cpu_partial_drain_attr.attr,
  #endif
  #ifdef CONFIG_FAILSLAB
  	&failslab_attr.attr,
  #endif
  	&usersize_attr.attr,
  
  	NULL
  };
  
  static const struct attribute_group slab_attr_group = {
  	.attrs = slab_attrs,
  };
  
  static ssize_t slab_attr_show(struct kobject *kobj,
  				struct attribute *attr,
  				char *buf)
  {
  	struct slab_attribute *attribute;
  	struct kmem_cache *s;
  	int err;
  
  	attribute = to_slab_attr(attr);
  	s = to_slab(kobj);
  
  	if (!attribute->show)
  		return -EIO;
  
  	err = attribute->show(s, buf);
  
  	return err;
  }
  
  static ssize_t slab_attr_store(struct kobject *kobj,
  				struct attribute *attr,
  				const char *buf, size_t len)
  {
  	struct slab_attribute *attribute;
  	struct kmem_cache *s;
  	int err;
  
  	attribute = to_slab_attr(attr);
  	s = to_slab(kobj);
  
  	if (!attribute->store)
  		return -EIO;
  
  	err = attribute->store(s, buf, len);
  #ifdef CONFIG_MEMCG
  	if (slab_state >= FULL && err >= 0 && is_root_cache(s)) {
  		struct kmem_cache *c;
  
  		mutex_lock(&slab_mutex);
  		if (s->max_attr_size < len)
  			s->max_attr_size = len;
  
  		/*
  		 * This is a best effort propagation, so this function's return
  		 * value will be determined by the parent cache only. This is
  		 * basically because not all attributes will have a well
  		 * defined semantics for rollbacks - most of the actions will
  		 * have permanent effects.
  		 *
  		 * Returning the error value of any of the children that fail
  		 * is not 100 % defined, in the sense that users seeing the
  		 * error code won't be able to know anything about the state of
  		 * the cache.
  		 *
  		 * Only returning the error code for the parent cache at least
  		 * has well defined semantics. The cache being written to
  		 * directly either failed or succeeded, in which case we loop
  		 * through the descendants with best-effort propagation.
  		 */
  		for_each_memcg_cache(c, s)
  			attribute->store(c, buf, len);
  		mutex_unlock(&slab_mutex);
  	}
  #endif
  	return err;
  }
  
  static void memcg_propagate_slab_attrs(struct kmem_cache *s)
  {
  #ifdef CONFIG_MEMCG
  	int i;
  	char *buffer = NULL;
  	struct kmem_cache *root_cache;
  
  	if (is_root_cache(s))
  		return;
  
  	root_cache = s->memcg_params.root_cache;
  
  	/*
  	 * This mean this cache had no attribute written. Therefore, no point
  	 * in copying default values around
  	 */
  	if (!root_cache->max_attr_size)
  		return;
  
  	for (i = 0; i < ARRAY_SIZE(slab_attrs); i++) {
  		char mbuf[64];
  		char *buf;
  		struct slab_attribute *attr = to_slab_attr(slab_attrs[i]);
  		ssize_t len;
  
  		if (!attr || !attr->store || !attr->show)
  			continue;
  
  		/*
  		 * It is really bad that we have to allocate here, so we will
  		 * do it only as a fallback. If we actually allocate, though,
  		 * we can just use the allocated buffer until the end.
  		 *
  		 * Most of the slub attributes will tend to be very small in
  		 * size, but sysfs allows buffers up to a page, so they can
  		 * theoretically happen.
  		 */
  		if (buffer)
  			buf = buffer;
  		else if (root_cache->max_attr_size < ARRAY_SIZE(mbuf))
  			buf = mbuf;
  		else {
  			buffer = (char *) get_zeroed_page(GFP_KERNEL);
  			if (WARN_ON(!buffer))
  				continue;
  			buf = buffer;
  		}
  
  		len = attr->show(root_cache, buf);
  		if (len > 0)
  			attr->store(s, buf, len);
  	}
  
  	if (buffer)
  		free_page((unsigned long)buffer);
  #endif
  }
  
  static void kmem_cache_release(struct kobject *k)
  {
  	slab_kmem_cache_release(to_slab(k));
  }
  
  static const struct sysfs_ops slab_sysfs_ops = {
  	.show = slab_attr_show,
  	.store = slab_attr_store,
  };
  
  static struct kobj_type slab_ktype = {
  	.sysfs_ops = &slab_sysfs_ops,
  	.release = kmem_cache_release,
  };
  
  static int uevent_filter(struct kset *kset, struct kobject *kobj)
  {
  	struct kobj_type *ktype = get_ktype(kobj);
  
  	if (ktype == &slab_ktype)
  		return 1;
  	return 0;
  }
  
  static const struct kset_uevent_ops slab_uevent_ops = {
  	.filter = uevent_filter,
  };
  
  static struct kset *slab_kset;
  
  static inline struct kset *cache_kset(struct kmem_cache *s)
  {
  #ifdef CONFIG_MEMCG
  	if (!is_root_cache(s))
  		return s->memcg_params.root_cache->memcg_kset;
  #endif
  	return slab_kset;
  }
  
  #define ID_STR_LENGTH 64
  
  /* Create a unique string id for a slab cache:
   *
   * Format	:[flags-]size
   */
  static char *create_unique_id(struct kmem_cache *s)
  {
  	char *name = kmalloc(ID_STR_LENGTH, GFP_KERNEL);
  	char *p = name;
  
  	BUG_ON(!name);
  
  	*p++ = ':';
  	/*
  	 * First flags affecting slabcache operations. We will only
  	 * get here for aliasable slabs so we do not need to support
  	 * too many flags. The flags here must cover all flags that
  	 * are matched during merging to guarantee that the id is
  	 * unique.
  	 */
  	if (s->flags & SLAB_CACHE_DMA)
  		*p++ = 'd';
  	if (s->flags & SLAB_RECLAIM_ACCOUNT)
  		*p++ = 'a';
  	if (s->flags & SLAB_CONSISTENCY_CHECKS)
  		*p++ = 'F';
  	if (s->flags & SLAB_ACCOUNT)
  		*p++ = 'A';
  	if (p != name + 1)
  		*p++ = '-';
  	p += sprintf(p, "%07u", s->size);
  
  	BUG_ON(p > name + ID_STR_LENGTH - 1);
  	return name;
  }
  
  static void sysfs_slab_remove_workfn(struct work_struct *work)
  {
  	struct kmem_cache *s =
  		container_of(work, struct kmem_cache, kobj_remove_work);
  
  	if (!s->kobj.state_in_sysfs)
  		/*
  		 * For a memcg cache, this may be called during
  		 * deactivation and again on shutdown.  Remove only once.
  		 * A cache is never shut down before deactivation is
  		 * complete, so no need to worry about synchronization.
  		 */
  		goto out;
  
  #ifdef CONFIG_MEMCG
  	kset_unregister(s->memcg_kset);
  #endif
  	kobject_uevent(&s->kobj, KOBJ_REMOVE);
  	kobject_del(&s->kobj);
  out:
  	kobject_put(&s->kobj);
  }
  
  static int sysfs_slab_add(struct kmem_cache *s)
  {
  	int err;
  	const char *name;
  	struct kset *kset = cache_kset(s);
  	int unmergeable = slab_unmergeable(s);
  
  	INIT_WORK(&s->kobj_remove_work, sysfs_slab_remove_workfn);
  
  	if (!kset) {
  		kobject_init(&s->kobj, &slab_ktype);
  		return 0;
  	}
  
  	if (!unmergeable && disable_higher_order_debug &&
  			(slub_debug & DEBUG_METADATA_FLAGS))
  		unmergeable = 1;
  
  	if (unmergeable) {
  		/*
  		 * Slabcache can never be merged so we can use the name proper.
  		 * This is typically the case for debug situations. In that
  		 * case we can catch duplicate names easily.
  		 */
  		sysfs_remove_link(&slab_kset->kobj, s->name);
  		name = s->name;
  	} else {
  		/*
  		 * Create a unique name for the slab as a target
  		 * for the symlinks.
  		 */
  		name = create_unique_id(s);
  	}
  
  	s->kobj.kset = kset;
  	err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name);
  	if (err)
  		goto out;
  
  	err = sysfs_create_group(&s->kobj, &slab_attr_group);
  	if (err)
  		goto out_del_kobj;
  
  #ifdef CONFIG_MEMCG
  	if (is_root_cache(s) && memcg_sysfs_enabled) {
  		s->memcg_kset = kset_create_and_add("cgroup", NULL, &s->kobj);
  		if (!s->memcg_kset) {
  			err = -ENOMEM;
  			goto out_del_kobj;
  		}
  	}
  #endif
  
  	kobject_uevent(&s->kobj, KOBJ_ADD);
  	if (!unmergeable) {
  		/* Setup first alias */
  		sysfs_slab_alias(s, s->name);
  	}
  out:
  	if (!unmergeable)
  		kfree(name);
  	return err;
  out_del_kobj:
  	kobject_del(&s->kobj);
  	goto out;
  }
  
  static void sysfs_slab_remove(struct kmem_cache *s)
  {
  	if (slab_state < FULL)
  		/*
  		 * Sysfs has not been setup yet so no need to remove the
  		 * cache from sysfs.
  		 */
  		return;
  
  	kobject_get(&s->kobj);
  	schedule_work(&s->kobj_remove_work);
  }
  
  void sysfs_slab_release(struct kmem_cache *s)
  {
  	if (slab_state >= FULL)
  		kobject_put(&s->kobj);
  }
  
  /*
   * Need to buffer aliases during bootup until sysfs becomes
   * available lest we lose that information.
   */
  struct saved_alias {
  	struct kmem_cache *s;
  	const char *name;
  	struct saved_alias *next;
  };
  
  static struct saved_alias *alias_list;
  
  static int sysfs_slab_alias(struct kmem_cache *s, const char *name)
  {
  	struct saved_alias *al;
  
  	if (slab_state == FULL) {
  		/*
  		 * If we have a leftover link then remove it.
  		 */
  		sysfs_remove_link(&slab_kset->kobj, name);
  		return sysfs_create_link(&slab_kset->kobj, &s->kobj, name);
  	}
  
  	al = kmalloc(sizeof(struct saved_alias), GFP_KERNEL);
  	if (!al)
  		return -ENOMEM;
  
  	al->s = s;
  	al->name = name;
  	al->next = alias_list;
  	alias_list = al;
  	return 0;
  }
  
  static int __init slab_sysfs_init(void)
  {
  	struct kmem_cache *s;
  	int err;
  
  	mutex_lock(&slab_mutex);
  
  	slab_kset = kset_create_and_add("slab", &slab_uevent_ops, kernel_kobj);
  	if (!slab_kset) {
  		mutex_unlock(&slab_mutex);
  		pr_err("Cannot register slab subsystem.\n");
  		return -ENOSYS;
  	}
  
  	slab_state = FULL;
  
  	list_for_each_entry(s, &slab_caches, list) {
  		err = sysfs_slab_add(s);
  		if (err)
  			pr_err("SLUB: Unable to add boot slab %s to sysfs\n",
  			       s->name);
  	}
  
  	while (alias_list) {
  		struct saved_alias *al = alias_list;
  
  		alias_list = alias_list->next;
  		err = sysfs_slab_alias(al->s, al->name);
  		if (err)
  			pr_err("SLUB: Unable to add boot slab alias %s to sysfs\n",
  			       al->name);
  		kfree(al);
  	}
  
  	mutex_unlock(&slab_mutex);
  	resiliency_test();
  	return 0;
  }
  
  __initcall(slab_sysfs_init);
  #endif /* CONFIG_SYSFS */
  
  /*
   * The /proc/slabinfo ABI
   */
  #ifdef CONFIG_SLUB_DEBUG
  void get_slabinfo(struct kmem_cache *s, struct slabinfo *sinfo)
  {
  	unsigned long nr_slabs = 0;
  	unsigned long nr_objs = 0;
  	unsigned long nr_free = 0;
  	int node;
  	struct kmem_cache_node *n;
  
  	for_each_kmem_cache_node(s, node, n) {
  		nr_slabs += node_nr_slabs(n);
  		nr_objs += node_nr_objs(n);
  		nr_free += count_partial(n, count_free);
  	}
  
  	sinfo->active_objs = nr_objs - nr_free;
  	sinfo->num_objs = nr_objs;
  	sinfo->active_slabs = nr_slabs;
  	sinfo->num_slabs = nr_slabs;
  	sinfo->objects_per_slab = oo_objects(s->oo);
  	sinfo->cache_order = oo_order(s->oo);
  }
  
  void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s)
  {
  }
  
  ssize_t slabinfo_write(struct file *file, const char __user *buffer,
  		       size_t count, loff_t *ppos)
  {
  	return -EIO;
  }
  #endif /* CONFIG_SLUB_DEBUG */
  