TOMOYO Linux Cross Reference
Linux/mm/slub.c

   // SPDX-License-Identifier: GPL-2.0
   /*
    * SLUB: A slab allocator that limits cache line use instead of queuing
    * objects in per cpu and per node lists.
    *
    * The allocator synchronizes using per slab locks or atomic 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 int slab_index(void *p, struct kmem_cache *s, void *addr)
 {
         return (p - addr) / s->size;
 }
 
 static inline int order_objects(int order, unsigned long size, int reserved)
 {
         return ((PAGE_SIZE << order) - reserved) / size;
 }
 
 static inline struct kmem_cache_order_objects oo_make(int order,
                 unsigned long size, int reserved)
 {
         struct kmem_cache_order_objects x = {
                 (order << OO_SHIFT) + order_objects(order, size, reserved)
         };
 
         return x;
 }
 
 static inline int oo_order(struct kmem_cache_order_objects x)
 {
         return x.x >> OO_SHIFT;
 }
 
 static inline 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 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)
 {
         if (!t->addr)
                 return;
 
         pr_err("INFO: %s in %pS age=%lu cpu=%u pid=%d\n",
                s, (void *)t->addr, jiffies - 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)
 {
         if (!(s->flags & SLAB_STORE_USER))
                 return;
 
         print_track("Allocated", get_track(s, object, TRACK_ALLOC));
         print_track("Freed", get_track(s, object, TRACK_FREE));
 }
 
 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 long, 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 long 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 long 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;
         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)
 {
         int err;
         unsigned long i, count = oo_objects(s->oo);
 
         /* 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) {
                 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;
         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: %d, buffer size: %d, default order: %d, min order: %d\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 int slub_min_order;
 static int slub_max_order = PAGE_ALLOC_COSTLY_ORDER;
 static 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 int slab_order(int size, int min_objects,
                                 int max_order, int fract_leftover, int reserved)
 {
         int order;
         int rem;
         int min_order = slub_min_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, get_order(min_objects * size + reserved));
                         order <= max_order; order++) {
 
                 unsigned long slab_size = PAGE_SIZE << order;
 
                 rem = (slab_size - reserved) % size;
 
                 if (rem <= slab_size / fract_leftover)
                         break;
         }
 
         return order;
 }
 
 static inline int calculate_order(int size, int reserved)
 {
         int order;
         int min_objects;
         int fraction;
         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) {
                 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;
         size_t size = s->object_size;
         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 (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=%lu realsize=%u order=%u offset=%u flags=%lx\n",
                       s->name, (unsigned long)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);
 }
 
 /*
  * 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, &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, &slub_max_order);
         slub_max_order = min(slub_max_order, 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, &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 long 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=%d-%d, MinObjects=%d, 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, size_t size, size_t 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, (int)size);
                 s->inuse = max_t(int, s->inuse, ALIGN(size, sizeof(void *)));
 
                 for_each_memcg_cache(c, s) {
                         c->object_size = s->object_size;
                         c->inuse = max_t(int, 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, "%d\n", s->size);
 }
 SLAB_ATTR_RO(slab_size);
 
 static ssize_t align_show(struct kmem_cache *s, char *buf)
 {
         return sprintf(buf, "%d\n", s->align);
 }
 SLAB_ATTR_RO(align);
 
 static ssize_t object_size_show(struct kmem_cache *s, char *buf)
 {
         return sprintf(buf, "%d\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, "%d\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 long order;
         int err;
 
         err = kstrtoul(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, "%d\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 long objects;
         int err;
 
         err = kstrtoul(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, "%zu\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, "%d\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, "%d\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 long ratio;
         int err;
 
         err = kstrtoul(buf, 10, &ratio);
         if (err)
                 return err;
 
         if (ratio <= 100)
                 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] != '')                                      \
                 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, "%07d", 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 */