mm/slab.c

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This source file includes following definitions.
obj_offset
dbg_redzone1
dbg_redzone2
dbg_userword
index_to_obj
cpu_cache_get
cache_estimate
__slab_error
noaliencache_setup
slab_max_order_setup
init_reap_node
next_reap_node
start_cpu_timer
init_arraycache
alloc_arraycache
cache_free_pfmemalloc
transfer_objects
alloc_alien_cache
free_alien_cache
cache_free_alien
alternate_node_alloc
____cache_alloc_node
gfp_exact_node
__alloc_alien_cache
alloc_alien_cache
free_alien_cache
__drain_alien_cache
reap_alien
drain_alien_cache
__cache_free_alien
cache_free_alien
gfp_exact_node
init_cache_node
init_cache_node_node
setup_kmem_cache_node
cpuup_canceled
cpuup_prepare
slab_prepare_cpu
slab_dead_cpu
slab_online_cpu
slab_offline_cpu
drain_cache_node_node
slab_memory_callback
init_list
set_up_node
kmem_cache_init
kmem_cache_init_late
cpucache_init
slab_out_of_memory
kmem_getpages
kmem_freepages
kmem_rcu_free
is_debug_pagealloc_cache
slab_kernel_map
slab_kernel_map
poison_obj
dump_line
print_objinfo
check_poison_obj
slab_destroy_debugcheck
slab_destroy_debugcheck
slab_destroy
slabs_destroy
calculate_slab_order
alloc_kmem_cache_cpus
setup_cpu_cache
kmem_cache_flags
__kmem_cache_alias
set_objfreelist_slab_cache
set_off_slab_cache
set_on_slab_cache
__kmem_cache_create
check_irq_off
check_irq_on
check_mutex_acquired
check_spinlock_acquired
check_spinlock_acquired_node
drain_array_locked
do_drain
drain_cpu_caches
drain_freelist
__kmem_cache_empty
__kmem_cache_shrink
__kmemcg_cache_deactivate
__kmemcg_cache_deactivate_after_rcu
__kmem_cache_shutdown
__kmem_cache_release
alloc_slabmgmt
get_free_obj
set_free_obj
cache_init_objs_debug
freelist_state_initialize
next_random_slot
swap_free_obj
shuffle_freelist
shuffle_freelist
cache_init_objs
slab_get_obj
slab_put_obj
slab_map_pages
cache_grow_begin
cache_grow_end
kfree_debugcheck
verify_redzone_free
cache_free_debugcheck
fixup_objfreelist_debug
fixup_slab_list
get_valid_first_slab
get_first_slab
cache_alloc_pfmemalloc
alloc_block
cache_alloc_refill
cache_alloc_debugcheck_before
cache_alloc_debugcheck_after
____cache_alloc
alternate_node_alloc
fallback_alloc
____cache_alloc_node
slab_alloc_node
__do_cache_alloc
__do_cache_alloc
slab_alloc
free_block
cache_flusharray
__cache_free
___cache_free
kmem_cache_alloc
cache_alloc_debugcheck_after_bulk
kmem_cache_alloc_bulk
kmem_cache_alloc_trace
kmem_cache_alloc_node
kmem_cache_alloc_node_trace
__do_kmalloc_node
__kmalloc_node
__kmalloc_node_track_caller
__do_kmalloc
__kmalloc
__kmalloc_track_caller
kmem_cache_free
kmem_cache_free_bulk
kfree
setup_kmem_cache_nodes
__do_tune_cpucache
do_tune_cpucache
enable_cpucache
drain_array
cache_reap
get_slabinfo
slabinfo_show_stats
slabinfo_write
__check_heap_object
__ksize
   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * linux/mm/slab.c
   4  * Written by Mark Hemment, 1996/97.
   5  * (markhe@nextd.demon.co.uk)
   6  *
   7  * kmem_cache_destroy() + some cleanup - 1999 Andrea Arcangeli
   8  *
   9  * Major cleanup, different bufctl logic, per-cpu arrays
  10  *      (c) 2000 Manfred Spraul
  11  *
  12  * Cleanup, make the head arrays unconditional, preparation for NUMA
  13  *      (c) 2002 Manfred Spraul
  14  *
  15  * An implementation of the Slab Allocator as described in outline in;
  16  *      UNIX Internals: The New Frontiers by Uresh Vahalia
  17  *      Pub: Prentice Hall      ISBN 0-13-101908-2
  18  * or with a little more detail in;
  19  *      The Slab Allocator: An Object-Caching Kernel Memory Allocator
  20  *      Jeff Bonwick (Sun Microsystems).
  21  *      Presented at: USENIX Summer 1994 Technical Conference
  22  *
  23  * The memory is organized in caches, one cache for each object type.
  24  * (e.g. inode_cache, dentry_cache, buffer_head, vm_area_struct)
  25  * Each cache consists out of many slabs (they are small (usually one
  26  * page long) and always contiguous), and each slab contains multiple
  27  * initialized objects.
  28  *
  29  * This means, that your constructor is used only for newly allocated
  30  * slabs and you must pass objects with the same initializations to
  31  * kmem_cache_free.
  32  *
  33  * Each cache can only support one memory type (GFP_DMA, GFP_HIGHMEM,
  34  * normal). If you need a special memory type, then must create a new
  35  * cache for that memory type.
  36  *
  37  * In order to reduce fragmentation, the slabs are sorted in 3 groups:
  38  *   full slabs with 0 free objects
  39  *   partial slabs
  40  *   empty slabs with no allocated objects
  41  *
  42  * If partial slabs exist, then new allocations come from these slabs,
  43  * otherwise from empty slabs or new slabs are allocated.
  44  *
  45  * kmem_cache_destroy() CAN CRASH if you try to allocate from the cache
  46  * during kmem_cache_destroy(). The caller must prevent concurrent allocs.
  47  *
  48  * Each cache has a short per-cpu head array, most allocs
  49  * and frees go into that array, and if that array overflows, then 1/2
  50  * of the entries in the array are given back into the global cache.
  51  * The head array is strictly LIFO and should improve the cache hit rates.
  52  * On SMP, it additionally reduces the spinlock operations.
  53  *
  54  * The c_cpuarray may not be read with enabled local interrupts -
  55  * it's changed with a smp_call_function().
  56  *
  57  * SMP synchronization:
  58  *  constructors and destructors are called without any locking.
  59  *  Several members in struct kmem_cache and struct slab never change, they
  60  *      are accessed without any locking.
  61  *  The per-cpu arrays are never accessed from the wrong cpu, no locking,
  62  *      and local interrupts are disabled so slab code is preempt-safe.
  63  *  The non-constant members are protected with a per-cache irq spinlock.
  64  *
  65  * Many thanks to Mark Hemment, who wrote another per-cpu slab patch
  66  * in 2000 - many ideas in the current implementation are derived from
  67  * his patch.
  68  *
  69  * Further notes from the original documentation:
  70  *
  71  * 11 April '97.  Started multi-threading - markhe
  72  *      The global cache-chain is protected by the mutex 'slab_mutex'.
  73  *      The sem is only needed when accessing/extending the cache-chain, which
  74  *      can never happen inside an interrupt (kmem_cache_create(),
  75  *      kmem_cache_shrink() and kmem_cache_reap()).
  76  *
  77  *      At present, each engine can be growing a cache.  This should be blocked.
  78  *
  79  * 15 March 2005. NUMA slab allocator.
  80  *      Shai Fultheim <shai@scalex86.org>.
  81  *      Shobhit Dayal <shobhit@calsoftinc.com>
  82  *      Alok N Kataria <alokk@calsoftinc.com>
  83  *      Christoph Lameter <christoph@lameter.com>
  84  *
  85  *      Modified the slab allocator to be node aware on NUMA systems.
  86  *      Each node has its own list of partial, free and full slabs.
  87  *      All object allocations for a node occur from node specific slab lists.
  88  */
  89 
  90 #include        <linux/slab.h>
  91 #include        <linux/mm.h>
  92 #include        <linux/poison.h>
  93 #include        <linux/swap.h>
  94 #include        <linux/cache.h>
  95 #include        <linux/interrupt.h>
  96 #include        <linux/init.h>
  97 #include        <linux/compiler.h>
  98 #include        <linux/cpuset.h>
  99 #include        <linux/proc_fs.h>
 100 #include        <linux/seq_file.h>
 101 #include        <linux/notifier.h>
 102 #include        <linux/kallsyms.h>
 103 #include        <linux/cpu.h>
 104 #include        <linux/sysctl.h>
 105 #include        <linux/module.h>
 106 #include        <linux/rcupdate.h>
 107 #include        <linux/string.h>
 108 #include        <linux/uaccess.h>
 109 #include        <linux/nodemask.h>
 110 #include        <linux/kmemleak.h>
 111 #include        <linux/mempolicy.h>
 112 #include        <linux/mutex.h>
 113 #include        <linux/fault-inject.h>
 114 #include        <linux/rtmutex.h>
 115 #include        <linux/reciprocal_div.h>
 116 #include        <linux/debugobjects.h>
 117 #include        <linux/memory.h>
 118 #include        <linux/prefetch.h>
 119 #include        <linux/sched/task_stack.h>
 120 
 121 #include        <net/sock.h>
 122 
 123 #include        <asm/cacheflush.h>
 124 #include        <asm/tlbflush.h>
 125 #include        <asm/page.h>
 126 
 127 #include <trace/events/kmem.h>
 128 
 129 #include        "internal.h"
 130 
 131 #include        "slab.h"
 132 
 133 /*
 134  * DEBUG        - 1 for kmem_cache_create() to honour; SLAB_RED_ZONE & SLAB_POISON.
 135  *                0 for faster, smaller code (especially in the critical paths).
 136  *
 137  * STATS        - 1 to collect stats for /proc/slabinfo.
 138  *                0 for faster, smaller code (especially in the critical paths).
 139  *
 140  * FORCED_DEBUG - 1 enables SLAB_RED_ZONE and SLAB_POISON (if possible)
 141  */
 142 
 143 #ifdef CONFIG_DEBUG_SLAB
 144 #define DEBUG           1
 145 #define STATS           1
 146 #define FORCED_DEBUG    1
 147 #else
 148 #define DEBUG           0
 149 #define STATS           0
 150 #define FORCED_DEBUG    0
 151 #endif
 152 
 153 /* Shouldn't this be in a header file somewhere? */
 154 #define BYTES_PER_WORD          sizeof(void *)
 155 #define REDZONE_ALIGN           max(BYTES_PER_WORD, __alignof__(unsigned long long))
 156 
 157 #ifndef ARCH_KMALLOC_FLAGS
 158 #define ARCH_KMALLOC_FLAGS SLAB_HWCACHE_ALIGN
 159 #endif
 160 
 161 #define FREELIST_BYTE_INDEX (((PAGE_SIZE >> BITS_PER_BYTE) \
 162                                 <= SLAB_OBJ_MIN_SIZE) ? 1 : 0)
 163 
 164 #if FREELIST_BYTE_INDEX
 165 typedef unsigned char freelist_idx_t;
 166 #else
 167 typedef unsigned short freelist_idx_t;
 168 #endif
 169 
 170 #define SLAB_OBJ_MAX_NUM ((1 << sizeof(freelist_idx_t) * BITS_PER_BYTE) - 1)
 171 
 172 /*
 173  * struct array_cache
 174  *
 175  * Purpose:
 176  * - LIFO ordering, to hand out cache-warm objects from _alloc
 177  * - reduce the number of linked list operations
 178  * - reduce spinlock operations
 179  *
 180  * The limit is stored in the per-cpu structure to reduce the data cache
 181  * footprint.
 182  *
 183  */
 184 struct array_cache {
 185         unsigned int avail;
 186         unsigned int limit;
 187         unsigned int batchcount;
 188         unsigned int touched;
 189         void *entry[];  /*
 190                          * Must have this definition in here for the proper
 191                          * alignment of array_cache. Also simplifies accessing
 192                          * the entries.
 193                          */
 194 };
 195 
 196 struct alien_cache {
 197         spinlock_t lock;
 198         struct array_cache ac;
 199 };
 200 
 201 /*
 202  * Need this for bootstrapping a per node allocator.
 203  */
 204 #define NUM_INIT_LISTS (2 * MAX_NUMNODES)
 205 static struct kmem_cache_node __initdata init_kmem_cache_node[NUM_INIT_LISTS];
 206 #define CACHE_CACHE 0
 207 #define SIZE_NODE (MAX_NUMNODES)
 208 
 209 static int drain_freelist(struct kmem_cache *cache,
 210                         struct kmem_cache_node *n, int tofree);
 211 static void free_block(struct kmem_cache *cachep, void **objpp, int len,
 212                         int node, struct list_head *list);
 213 static void slabs_destroy(struct kmem_cache *cachep, struct list_head *list);
 214 static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp);
 215 static void cache_reap(struct work_struct *unused);
 216 
 217 static inline void fixup_objfreelist_debug(struct kmem_cache *cachep,
 218                                                 void **list);
 219 static inline void fixup_slab_list(struct kmem_cache *cachep,
 220                                 struct kmem_cache_node *n, struct page *page,
 221                                 void **list);
 222 static int slab_early_init = 1;
 223 
 224 #define INDEX_NODE kmalloc_index(sizeof(struct kmem_cache_node))
 225 
 226 static void kmem_cache_node_init(struct kmem_cache_node *parent)
 227 {
 228         INIT_LIST_HEAD(&parent->slabs_full);
 229         INIT_LIST_HEAD(&parent->slabs_partial);
 230         INIT_LIST_HEAD(&parent->slabs_free);
 231         parent->total_slabs = 0;
 232         parent->free_slabs = 0;
 233         parent->shared = NULL;
 234         parent->alien = NULL;
 235         parent->colour_next = 0;
 236         spin_lock_init(&parent->list_lock);
 237         parent->free_objects = 0;
 238         parent->free_touched = 0;
 239 }
 240 
 241 #define MAKE_LIST(cachep, listp, slab, nodeid)                          \
 242         do {                                                            \
 243                 INIT_LIST_HEAD(listp);                                  \
 244                 list_splice(&get_node(cachep, nodeid)->slab, listp);    \
 245         } while (0)
 246 
 247 #define MAKE_ALL_LISTS(cachep, ptr, nodeid)                             \
 248         do {                                                            \
 249         MAKE_LIST((cachep), (&(ptr)->slabs_full), slabs_full, nodeid);  \
 250         MAKE_LIST((cachep), (&(ptr)->slabs_partial), slabs_partial, nodeid); \
 251         MAKE_LIST((cachep), (&(ptr)->slabs_free), slabs_free, nodeid);  \
 252         } while (0)
 253 
 254 #define CFLGS_OBJFREELIST_SLAB  ((slab_flags_t __force)0x40000000U)
 255 #define CFLGS_OFF_SLAB          ((slab_flags_t __force)0x80000000U)
 256 #define OBJFREELIST_SLAB(x)     ((x)->flags & CFLGS_OBJFREELIST_SLAB)
 257 #define OFF_SLAB(x)     ((x)->flags & CFLGS_OFF_SLAB)
 258 
 259 #define BATCHREFILL_LIMIT       16
 260 /*
 261  * Optimization question: fewer reaps means less probability for unnessary
 262  * cpucache drain/refill cycles.
 263  *
 264  * OTOH the cpuarrays can contain lots of objects,
 265  * which could lock up otherwise freeable slabs.
 266  */
 267 #define REAPTIMEOUT_AC          (2*HZ)
 268 #define REAPTIMEOUT_NODE        (4*HZ)
 269 
 270 #if STATS
 271 #define STATS_INC_ACTIVE(x)     ((x)->num_active++)
 272 #define STATS_DEC_ACTIVE(x)     ((x)->num_active--)
 273 #define STATS_INC_ALLOCED(x)    ((x)->num_allocations++)
 274 #define STATS_INC_GROWN(x)      ((x)->grown++)
 275 #define STATS_ADD_REAPED(x,y)   ((x)->reaped += (y))
 276 #define STATS_SET_HIGH(x)                                               \
 277         do {                                                            \
 278                 if ((x)->num_active > (x)->high_mark)                   \
 279                         (x)->high_mark = (x)->num_active;               \
 280         } while (0)
 281 #define STATS_INC_ERR(x)        ((x)->errors++)
 282 #define STATS_INC_NODEALLOCS(x) ((x)->node_allocs++)
 283 #define STATS_INC_NODEFREES(x)  ((x)->node_frees++)
 284 #define STATS_INC_ACOVERFLOW(x)   ((x)->node_overflow++)
 285 #define STATS_SET_FREEABLE(x, i)                                        \
 286         do {                                                            \
 287                 if ((x)->max_freeable < i)                              \
 288                         (x)->max_freeable = i;                          \
 289         } while (0)
 290 #define STATS_INC_ALLOCHIT(x)   atomic_inc(&(x)->allochit)
 291 #define STATS_INC_ALLOCMISS(x)  atomic_inc(&(x)->allocmiss)
 292 #define STATS_INC_FREEHIT(x)    atomic_inc(&(x)->freehit)
 293 #define STATS_INC_FREEMISS(x)   atomic_inc(&(x)->freemiss)
 294 #else
 295 #define STATS_INC_ACTIVE(x)     do { } while (0)
 296 #define STATS_DEC_ACTIVE(x)     do { } while (0)
 297 #define STATS_INC_ALLOCED(x)    do { } while (0)
 298 #define STATS_INC_GROWN(x)      do { } while (0)
 299 #define STATS_ADD_REAPED(x,y)   do { (void)(y); } while (0)
 300 #define STATS_SET_HIGH(x)       do { } while (0)
 301 #define STATS_INC_ERR(x)        do { } while (0)
 302 #define STATS_INC_NODEALLOCS(x) do { } while (0)
 303 #define STATS_INC_NODEFREES(x)  do { } while (0)
 304 #define STATS_INC_ACOVERFLOW(x)   do { } while (0)
 305 #define STATS_SET_FREEABLE(x, i) do { } while (0)
 306 #define STATS_INC_ALLOCHIT(x)   do { } while (0)
 307 #define STATS_INC_ALLOCMISS(x)  do { } while (0)
 308 #define STATS_INC_FREEHIT(x)    do { } while (0)
 309 #define STATS_INC_FREEMISS(x)   do { } while (0)
 310 #endif
 311 
 312 #if DEBUG
 313 
 314 /*
 315  * memory layout of objects:
 316  * 0            : objp
 317  * 0 .. cachep->obj_offset - BYTES_PER_WORD - 1: padding. This ensures that
 318  *              the end of an object is aligned with the end of the real
 319  *              allocation. Catches writes behind the end of the allocation.
 320  * cachep->obj_offset - BYTES_PER_WORD .. cachep->obj_offset - 1:
 321  *              redzone word.
 322  * cachep->obj_offset: The real object.
 323  * cachep->size - 2* BYTES_PER_WORD: redzone word [BYTES_PER_WORD long]
 324  * cachep->size - 1* BYTES_PER_WORD: last caller address
 325  *                                      [BYTES_PER_WORD long]
 326  */
 327 static int obj_offset(struct kmem_cache *cachep)
 328 {
 329         return cachep->obj_offset;
 330 }
 331 
 332 static unsigned long long *dbg_redzone1(struct kmem_cache *cachep, void *objp)
 333 {
 334         BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
 335         return (unsigned long long*) (objp + obj_offset(cachep) -
 336                                       sizeof(unsigned long long));
 337 }
 338 
 339 static unsigned long long *dbg_redzone2(struct kmem_cache *cachep, void *objp)
 340 {
 341         BUG_ON(!(cachep->flags & SLAB_RED_ZONE));
 342         if (cachep->flags & SLAB_STORE_USER)
 343                 return (unsigned long long *)(objp + cachep->size -
 344                                               sizeof(unsigned long long) -
 345                                               REDZONE_ALIGN);
 346         return (unsigned long long *) (objp + cachep->size -
 347                                        sizeof(unsigned long long));
 348 }
 349 
 350 static void **dbg_userword(struct kmem_cache *cachep, void *objp)
 351 {
 352         BUG_ON(!(cachep->flags & SLAB_STORE_USER));
 353         return (void **)(objp + cachep->size - BYTES_PER_WORD);
 354 }
 355 
 356 #else
 357 
 358 #define obj_offset(x)                   0
 359 #define dbg_redzone1(cachep, objp)      ({BUG(); (unsigned long long *)NULL;})
 360 #define dbg_redzone2(cachep, objp)      ({BUG(); (unsigned long long *)NULL;})
 361 #define dbg_userword(cachep, objp)      ({BUG(); (void **)NULL;})
 362 
 363 #endif
 364 
 365 /*
 366  * Do not go above this order unless 0 objects fit into the slab or
 367  * overridden on the command line.
 368  */
 369 #define SLAB_MAX_ORDER_HI       1
 370 #define SLAB_MAX_ORDER_LO       0
 371 static int slab_max_order = SLAB_MAX_ORDER_LO;
 372 static bool slab_max_order_set __initdata;
 373 
 374 static inline void *index_to_obj(struct kmem_cache *cache, struct page *page,
 375                                  unsigned int idx)
 376 {
 377         return page->s_mem + cache->size * idx;
 378 }
 379 
 380 #define BOOT_CPUCACHE_ENTRIES   1
 381 /* internal cache of cache description objs */
 382 static struct kmem_cache kmem_cache_boot = {
 383         .batchcount = 1,
 384         .limit = BOOT_CPUCACHE_ENTRIES,
 385         .shared = 1,
 386         .size = sizeof(struct kmem_cache),
 387         .name = "kmem_cache",
 388 };
 389 
 390 static DEFINE_PER_CPU(struct delayed_work, slab_reap_work);
 391 
 392 static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
 393 {
 394         return this_cpu_ptr(cachep->cpu_cache);
 395 }
 396 
 397 /*
 398  * Calculate the number of objects and left-over bytes for a given buffer size.
 399  */
 400 static unsigned int cache_estimate(unsigned long gfporder, size_t buffer_size,
 401                 slab_flags_t flags, size_t *left_over)
 402 {
 403         unsigned int num;
 404         size_t slab_size = PAGE_SIZE << gfporder;
 405 
 406         /*
 407          * The slab management structure can be either off the slab or
 408          * on it. For the latter case, the memory allocated for a
 409          * slab is used for:
 410          *
 411          * - @buffer_size bytes for each object
 412          * - One freelist_idx_t for each object
 413          *
 414          * We don't need to consider alignment of freelist because
 415          * freelist will be at the end of slab page. The objects will be
 416          * at the correct alignment.
 417          *
 418          * If the slab management structure is off the slab, then the
 419          * alignment will already be calculated into the size. Because
 420          * the slabs are all pages aligned, the objects will be at the
 421          * correct alignment when allocated.
 422          */
 423         if (flags & (CFLGS_OBJFREELIST_SLAB | CFLGS_OFF_SLAB)) {
 424                 num = slab_size / buffer_size;
 425                 *left_over = slab_size % buffer_size;
 426         } else {
 427                 num = slab_size / (buffer_size + sizeof(freelist_idx_t));
 428                 *left_over = slab_size %
 429                         (buffer_size + sizeof(freelist_idx_t));
 430         }
 431 
 432         return num;
 433 }
 434 
 435 #if DEBUG
 436 #define slab_error(cachep, msg) __slab_error(__func__, cachep, msg)
 437 
 438 static void __slab_error(const char *function, struct kmem_cache *cachep,
 439                         char *msg)
 440 {
 441         pr_err("slab error in %s(): cache `%s': %s\n",
 442                function, cachep->name, msg);
 443         dump_stack();
 444         add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 445 }
 446 #endif
 447 
 448 /*
 449  * By default on NUMA we use alien caches to stage the freeing of
 450  * objects allocated from other nodes. This causes massive memory
 451  * inefficiencies when using fake NUMA setup to split memory into a
 452  * large number of small nodes, so it can be disabled on the command
 453  * line
 454   */
 455 
 456 static int use_alien_caches __read_mostly = 1;
 457 static int __init noaliencache_setup(char *s)
 458 {
 459         use_alien_caches = 0;
 460         return 1;
 461 }
 462 __setup("noaliencache", noaliencache_setup);
 463 
 464 static int __init slab_max_order_setup(char *str)
 465 {
 466         get_option(&str, &slab_max_order);
 467         slab_max_order = slab_max_order < 0 ? 0 :
 468                                 min(slab_max_order, MAX_ORDER - 1);
 469         slab_max_order_set = true;
 470 
 471         return 1;
 472 }
 473 __setup("slab_max_order=", slab_max_order_setup);
 474 
 475 #ifdef CONFIG_NUMA
 476 /*
 477  * Special reaping functions for NUMA systems called from cache_reap().
 478  * These take care of doing round robin flushing of alien caches (containing
 479  * objects freed on different nodes from which they were allocated) and the
 480  * flushing of remote pcps by calling drain_node_pages.
 481  */
 482 static DEFINE_PER_CPU(unsigned long, slab_reap_node);
 483 
 484 static void init_reap_node(int cpu)
 485 {
 486         per_cpu(slab_reap_node, cpu) = next_node_in(cpu_to_mem(cpu),
 487                                                     node_online_map);
 488 }
 489 
 490 static void next_reap_node(void)
 491 {
 492         int node = __this_cpu_read(slab_reap_node);
 493 
 494         node = next_node_in(node, node_online_map);
 495         __this_cpu_write(slab_reap_node, node);
 496 }
 497 
 498 #else
 499 #define init_reap_node(cpu) do { } while (0)
 500 #define next_reap_node(void) do { } while (0)
 501 #endif
 502 
 503 /*
 504  * Initiate the reap timer running on the target CPU.  We run at around 1 to 2Hz
 505  * via the workqueue/eventd.
 506  * Add the CPU number into the expiration time to minimize the possibility of
 507  * the CPUs getting into lockstep and contending for the global cache chain
 508  * lock.
 509  */
 510 static void start_cpu_timer(int cpu)
 511 {
 512         struct delayed_work *reap_work = &per_cpu(slab_reap_work, cpu);
 513 
 514         if (reap_work->work.func == NULL) {
 515                 init_reap_node(cpu);
 516                 INIT_DEFERRABLE_WORK(reap_work, cache_reap);
 517                 schedule_delayed_work_on(cpu, reap_work,
 518                                         __round_jiffies_relative(HZ, cpu));
 519         }
 520 }
 521 
 522 static void init_arraycache(struct array_cache *ac, int limit, int batch)
 523 {
 524         if (ac) {
 525                 ac->avail = 0;
 526                 ac->limit = limit;
 527                 ac->batchcount = batch;
 528                 ac->touched = 0;
 529         }
 530 }
 531 
 532 static struct array_cache *alloc_arraycache(int node, int entries,
 533                                             int batchcount, gfp_t gfp)
 534 {
 535         size_t memsize = sizeof(void *) * entries + sizeof(struct array_cache);
 536         struct array_cache *ac = NULL;
 537 
 538         ac = kmalloc_node(memsize, gfp, node);
 539         /*
 540          * The array_cache structures contain pointers to free object.
 541          * However, when such objects are allocated or transferred to another
 542          * cache the pointers are not cleared and they could be counted as
 543          * valid references during a kmemleak scan. Therefore, kmemleak must
 544          * not scan such objects.
 545          */
 546         kmemleak_no_scan(ac);
 547         init_arraycache(ac, entries, batchcount);
 548         return ac;
 549 }
 550 
 551 static noinline void cache_free_pfmemalloc(struct kmem_cache *cachep,
 552                                         struct page *page, void *objp)
 553 {
 554         struct kmem_cache_node *n;
 555         int page_node;
 556         LIST_HEAD(list);
 557 
 558         page_node = page_to_nid(page);
 559         n = get_node(cachep, page_node);
 560 
 561         spin_lock(&n->list_lock);
 562         free_block(cachep, &objp, 1, page_node, &list);
 563         spin_unlock(&n->list_lock);
 564 
 565         slabs_destroy(cachep, &list);
 566 }
 567 
 568 /*
 569  * Transfer objects in one arraycache to another.
 570  * Locking must be handled by the caller.
 571  *
 572  * Return the number of entries transferred.
 573  */
 574 static int transfer_objects(struct array_cache *to,
 575                 struct array_cache *from, unsigned int max)
 576 {
 577         /* Figure out how many entries to transfer */
 578         int nr = min3(from->avail, max, to->limit - to->avail);
 579 
 580         if (!nr)
 581                 return 0;
 582 
 583         memcpy(to->entry + to->avail, from->entry + from->avail -nr,
 584                         sizeof(void *) *nr);
 585 
 586         from->avail -= nr;
 587         to->avail += nr;
 588         return nr;
 589 }
 590 
 591 #ifndef CONFIG_NUMA
 592 
 593 #define drain_alien_cache(cachep, alien) do { } while (0)
 594 #define reap_alien(cachep, n) do { } while (0)
 595 
 596 static inline struct alien_cache **alloc_alien_cache(int node,
 597                                                 int limit, gfp_t gfp)
 598 {
 599         return NULL;
 600 }
 601 
 602 static inline void free_alien_cache(struct alien_cache **ac_ptr)
 603 {
 604 }
 605 
 606 static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
 607 {
 608         return 0;
 609 }
 610 
 611 static inline void *alternate_node_alloc(struct kmem_cache *cachep,
 612                 gfp_t flags)
 613 {
 614         return NULL;
 615 }
 616 
 617 static inline void *____cache_alloc_node(struct kmem_cache *cachep,
 618                  gfp_t flags, int nodeid)
 619 {
 620         return NULL;
 621 }
 622 
 623 static inline gfp_t gfp_exact_node(gfp_t flags)
 624 {
 625         return flags & ~__GFP_NOFAIL;
 626 }
 627 
 628 #else   /* CONFIG_NUMA */
 629 
 630 static void *____cache_alloc_node(struct kmem_cache *, gfp_t, int);
 631 static void *alternate_node_alloc(struct kmem_cache *, gfp_t);
 632 
 633 static struct alien_cache *__alloc_alien_cache(int node, int entries,
 634                                                 int batch, gfp_t gfp)
 635 {
 636         size_t memsize = sizeof(void *) * entries + sizeof(struct alien_cache);
 637         struct alien_cache *alc = NULL;
 638 
 639         alc = kmalloc_node(memsize, gfp, node);
 640         if (alc) {
 641                 kmemleak_no_scan(alc);
 642                 init_arraycache(&alc->ac, entries, batch);
 643                 spin_lock_init(&alc->lock);
 644         }
 645         return alc;
 646 }
 647 
 648 static struct alien_cache **alloc_alien_cache(int node, int limit, gfp_t gfp)
 649 {
 650         struct alien_cache **alc_ptr;
 651         int i;
 652 
 653         if (limit > 1)
 654                 limit = 12;
 655         alc_ptr = kcalloc_node(nr_node_ids, sizeof(void *), gfp, node);
 656         if (!alc_ptr)
 657                 return NULL;
 658 
 659         for_each_node(i) {
 660                 if (i == node || !node_online(i))
 661                         continue;
 662                 alc_ptr[i] = __alloc_alien_cache(node, limit, 0xbaadf00d, gfp);
 663                 if (!alc_ptr[i]) {
 664                         for (i--; i >= 0; i--)
 665                                 kfree(alc_ptr[i]);
 666                         kfree(alc_ptr);
 667                         return NULL;
 668                 }
 669         }
 670         return alc_ptr;
 671 }
 672 
 673 static void free_alien_cache(struct alien_cache **alc_ptr)
 674 {
 675         int i;
 676 
 677         if (!alc_ptr)
 678                 return;
 679         for_each_node(i)
 680             kfree(alc_ptr[i]);
 681         kfree(alc_ptr);
 682 }
 683 
 684 static void __drain_alien_cache(struct kmem_cache *cachep,
 685                                 struct array_cache *ac, int node,
 686                                 struct list_head *list)
 687 {
 688         struct kmem_cache_node *n = get_node(cachep, node);
 689 
 690         if (ac->avail) {
 691                 spin_lock(&n->list_lock);
 692                 /*
 693                  * Stuff objects into the remote nodes shared array first.
 694                  * That way we could avoid the overhead of putting the objects
 695                  * into the free lists and getting them back later.
 696                  */
 697                 if (n->shared)
 698                         transfer_objects(n->shared, ac, ac->limit);
 699 
 700                 free_block(cachep, ac->entry, ac->avail, node, list);
 701                 ac->avail = 0;
 702                 spin_unlock(&n->list_lock);
 703         }
 704 }
 705 
 706 /*
 707  * Called from cache_reap() to regularly drain alien caches round robin.
 708  */
 709 static void reap_alien(struct kmem_cache *cachep, struct kmem_cache_node *n)
 710 {
 711         int node = __this_cpu_read(slab_reap_node);
 712 
 713         if (n->alien) {
 714                 struct alien_cache *alc = n->alien[node];
 715                 struct array_cache *ac;
 716 
 717                 if (alc) {
 718                         ac = &alc->ac;
 719                         if (ac->avail && spin_trylock_irq(&alc->lock)) {
 720                                 LIST_HEAD(list);
 721 
 722                                 __drain_alien_cache(cachep, ac, node, &list);
 723                                 spin_unlock_irq(&alc->lock);
 724                                 slabs_destroy(cachep, &list);
 725                         }
 726                 }
 727         }
 728 }
 729 
 730 static void drain_alien_cache(struct kmem_cache *cachep,
 731                                 struct alien_cache **alien)
 732 {
 733         int i = 0;
 734         struct alien_cache *alc;
 735         struct array_cache *ac;
 736         unsigned long flags;
 737 
 738         for_each_online_node(i) {
 739                 alc = alien[i];
 740                 if (alc) {
 741                         LIST_HEAD(list);
 742 
 743                         ac = &alc->ac;
 744                         spin_lock_irqsave(&alc->lock, flags);
 745                         __drain_alien_cache(cachep, ac, i, &list);
 746                         spin_unlock_irqrestore(&alc->lock, flags);
 747                         slabs_destroy(cachep, &list);
 748                 }
 749         }
 750 }
 751 
 752 static int __cache_free_alien(struct kmem_cache *cachep, void *objp,
 753                                 int node, int page_node)
 754 {
 755         struct kmem_cache_node *n;
 756         struct alien_cache *alien = NULL;
 757         struct array_cache *ac;
 758         LIST_HEAD(list);
 759 
 760         n = get_node(cachep, node);
 761         STATS_INC_NODEFREES(cachep);
 762         if (n->alien && n->alien[page_node]) {
 763                 alien = n->alien[page_node];
 764                 ac = &alien->ac;
 765                 spin_lock(&alien->lock);
 766                 if (unlikely(ac->avail == ac->limit)) {
 767                         STATS_INC_ACOVERFLOW(cachep);
 768                         __drain_alien_cache(cachep, ac, page_node, &list);
 769                 }
 770                 ac->entry[ac->avail++] = objp;
 771                 spin_unlock(&alien->lock);
 772                 slabs_destroy(cachep, &list);
 773         } else {
 774                 n = get_node(cachep, page_node);
 775                 spin_lock(&n->list_lock);
 776                 free_block(cachep, &objp, 1, page_node, &list);
 777                 spin_unlock(&n->list_lock);
 778                 slabs_destroy(cachep, &list);
 779         }
 780         return 1;
 781 }
 782 
 783 static inline int cache_free_alien(struct kmem_cache *cachep, void *objp)
 784 {
 785         int page_node = page_to_nid(virt_to_page(objp));
 786         int node = numa_mem_id();
 787         /*
 788          * Make sure we are not freeing a object from another node to the array
 789          * cache on this cpu.
 790          */
 791         if (likely(node == page_node))
 792                 return 0;
 793 
 794         return __cache_free_alien(cachep, objp, node, page_node);
 795 }
 796 
 797 /*
 798  * Construct gfp mask to allocate from a specific node but do not reclaim or
 799  * warn about failures.
 800  */
 801 static inline gfp_t gfp_exact_node(gfp_t flags)
 802 {
 803         return (flags | __GFP_THISNODE | __GFP_NOWARN) & ~(__GFP_RECLAIM|__GFP_NOFAIL);
 804 }
 805 #endif
 806 
 807 static int init_cache_node(struct kmem_cache *cachep, int node, gfp_t gfp)
 808 {
 809         struct kmem_cache_node *n;
 810 
 811         /*
 812          * Set up the kmem_cache_node for cpu before we can
 813          * begin anything. Make sure some other cpu on this
 814          * node has not already allocated this
 815          */
 816         n = get_node(cachep, node);
 817         if (n) {
 818                 spin_lock_irq(&n->list_lock);
 819                 n->free_limit = (1 + nr_cpus_node(node)) * cachep->batchcount +
 820                                 cachep->num;
 821                 spin_unlock_irq(&n->list_lock);
 822 
 823                 return 0;
 824         }
 825 
 826         n = kmalloc_node(sizeof(struct kmem_cache_node), gfp, node);
 827         if (!n)
 828                 return -ENOMEM;
 829 
 830         kmem_cache_node_init(n);
 831         n->next_reap = jiffies + REAPTIMEOUT_NODE +
 832                     ((unsigned long)cachep) % REAPTIMEOUT_NODE;
 833 
 834         n->free_limit =
 835                 (1 + nr_cpus_node(node)) * cachep->batchcount + cachep->num;
 836 
 837         /*
 838          * The kmem_cache_nodes don't come and go as CPUs
 839          * come and go.  slab_mutex is sufficient
 840          * protection here.
 841          */
 842         cachep->node[node] = n;
 843 
 844         return 0;
 845 }
 846 
 847 #if (defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG)) || defined(CONFIG_SMP)
 848 /*
 849  * Allocates and initializes node for a node on each slab cache, used for
 850  * either memory or cpu hotplug.  If memory is being hot-added, the kmem_cache_node
 851  * will be allocated off-node since memory is not yet online for the new node.
 852  * When hotplugging memory or a cpu, existing node are not replaced if
 853  * already in use.
 854  *
 855  * Must hold slab_mutex.
 856  */
 857 static int init_cache_node_node(int node)
 858 {
 859         int ret;
 860         struct kmem_cache *cachep;
 861 
 862         list_for_each_entry(cachep, &slab_caches, list) {
 863                 ret = init_cache_node(cachep, node, GFP_KERNEL);
 864                 if (ret)
 865                         return ret;
 866         }
 867 
 868         return 0;
 869 }
 870 #endif
 871 
 872 static int setup_kmem_cache_node(struct kmem_cache *cachep,
 873                                 int node, gfp_t gfp, bool force_change)
 874 {
 875         int ret = -ENOMEM;
 876         struct kmem_cache_node *n;
 877         struct array_cache *old_shared = NULL;
 878         struct array_cache *new_shared = NULL;
 879         struct alien_cache **new_alien = NULL;
 880         LIST_HEAD(list);
 881 
 882         if (use_alien_caches) {
 883                 new_alien = alloc_alien_cache(node, cachep->limit, gfp);
 884                 if (!new_alien)
 885                         goto fail;
 886         }
 887 
 888         if (cachep->shared) {
 889                 new_shared = alloc_arraycache(node,
 890                         cachep->shared * cachep->batchcount, 0xbaadf00d, gfp);
 891                 if (!new_shared)
 892                         goto fail;
 893         }
 894 
 895         ret = init_cache_node(cachep, node, gfp);
 896         if (ret)
 897                 goto fail;
 898 
 899         n = get_node(cachep, node);
 900         spin_lock_irq(&n->list_lock);
 901         if (n->shared && force_change) {
 902                 free_block(cachep, n->shared->entry,
 903                                 n->shared->avail, node, &list);
 904                 n->shared->avail = 0;
 905         }
 906 
 907         if (!n->shared || force_change) {
 908                 old_shared = n->shared;
 909                 n->shared = new_shared;
 910                 new_shared = NULL;
 911         }
 912 
 913         if (!n->alien) {
 914                 n->alien = new_alien;
 915                 new_alien = NULL;
 916         }
 917 
 918         spin_unlock_irq(&n->list_lock);
 919         slabs_destroy(cachep, &list);
 920 
 921         /*
 922          * To protect lockless access to n->shared during irq disabled context.
 923          * If n->shared isn't NULL in irq disabled context, accessing to it is
 924          * guaranteed to be valid until irq is re-enabled, because it will be
 925          * freed after synchronize_rcu().
 926          */
 927         if (old_shared && force_change)
 928                 synchronize_rcu();
 929 
 930 fail:
 931         kfree(old_shared);
 932         kfree(new_shared);
 933         free_alien_cache(new_alien);
 934 
 935         return ret;
 936 }
 937 
 938 #ifdef CONFIG_SMP
 939 
 940 static void cpuup_canceled(long cpu)
 941 {
 942         struct kmem_cache *cachep;
 943         struct kmem_cache_node *n = NULL;
 944         int node = cpu_to_mem(cpu);
 945         const struct cpumask *mask = cpumask_of_node(node);
 946 
 947         list_for_each_entry(cachep, &slab_caches, list) {
 948                 struct array_cache *nc;
 949                 struct array_cache *shared;
 950                 struct alien_cache **alien;
 951                 LIST_HEAD(list);
 952 
 953                 n = get_node(cachep, node);
 954                 if (!n)
 955                         continue;
 956 
 957                 spin_lock_irq(&n->list_lock);
 958 
 959                 /* Free limit for this kmem_cache_node */
 960                 n->free_limit -= cachep->batchcount;
 961 
 962                 /* cpu is dead; no one can alloc from it. */
 963                 nc = per_cpu_ptr(cachep->cpu_cache, cpu);
 964                 free_block(cachep, nc->entry, nc->avail, node, &list);
 965                 nc->avail = 0;
 966 
 967                 if (!cpumask_empty(mask)) {
 968                         spin_unlock_irq(&n->list_lock);
 969                         goto free_slab;
 970                 }
 971 
 972                 shared = n->shared;
 973                 if (shared) {
 974                         free_block(cachep, shared->entry,
 975                                    shared->avail, node, &list);
 976                         n->shared = NULL;
 977                 }
 978 
 979                 alien = n->alien;
 980                 n->alien = NULL;
 981 
 982                 spin_unlock_irq(&n->list_lock);
 983 
 984                 kfree(shared);
 985                 if (alien) {
 986                         drain_alien_cache(cachep, alien);
 987                         free_alien_cache(alien);
 988                 }
 989 
 990 free_slab:
 991                 slabs_destroy(cachep, &list);
 992         }
 993         /*
 994          * In the previous loop, all the objects were freed to
 995          * the respective cache's slabs,  now we can go ahead and
 996          * shrink each nodelist to its limit.
 997          */
 998         list_for_each_entry(cachep, &slab_caches, list) {
 999                 n = get_node(cachep, node);
1000                 if (!n)
1001                         continue;
1002                 drain_freelist(cachep, n, INT_MAX);
1003         }
1004 }
1005 
1006 static int cpuup_prepare(long cpu)
1007 {
1008         struct kmem_cache *cachep;
1009         int node = cpu_to_mem(cpu);
1010         int err;
1011 
1012         /*
1013          * We need to do this right in the beginning since
1014          * alloc_arraycache's are going to use this list.
1015          * kmalloc_node allows us to add the slab to the right
1016          * kmem_cache_node and not this cpu's kmem_cache_node
1017          */
1018         err = init_cache_node_node(node);
1019         if (err < 0)
1020                 goto bad;
1021 
1022         /*
1023          * Now we can go ahead with allocating the shared arrays and
1024          * array caches
1025          */
1026         list_for_each_entry(cachep, &slab_caches, list) {
1027                 err = setup_kmem_cache_node(cachep, node, GFP_KERNEL, false);
1028                 if (err)
1029                         goto bad;
1030         }
1031 
1032         return 0;
1033 bad:
1034         cpuup_canceled(cpu);
1035         return -ENOMEM;
1036 }
1037 
1038 int slab_prepare_cpu(unsigned int cpu)
1039 {
1040         int err;
1041 
1042         mutex_lock(&slab_mutex);
1043         err = cpuup_prepare(cpu);
1044         mutex_unlock(&slab_mutex);
1045         return err;
1046 }
1047 
1048 /*
1049  * This is called for a failed online attempt and for a successful
1050  * offline.
1051  *
1052  * Even if all the cpus of a node are down, we don't free the
1053  * kmem_list3 of any cache. This to avoid a race between cpu_down, and
1054  * a kmalloc allocation from another cpu for memory from the node of
1055  * the cpu going down.  The list3 structure is usually allocated from
1056  * kmem_cache_create() and gets destroyed at kmem_cache_destroy().
1057  */
1058 int slab_dead_cpu(unsigned int cpu)
1059 {
1060         mutex_lock(&slab_mutex);
1061         cpuup_canceled(cpu);
1062         mutex_unlock(&slab_mutex);
1063         return 0;
1064 }
1065 #endif
1066 
1067 static int slab_online_cpu(unsigned int cpu)
1068 {
1069         start_cpu_timer(cpu);
1070         return 0;
1071 }
1072 
1073 static int slab_offline_cpu(unsigned int cpu)
1074 {
1075         /*
1076          * Shutdown cache reaper. Note that the slab_mutex is held so
1077          * that if cache_reap() is invoked it cannot do anything
1078          * expensive but will only modify reap_work and reschedule the
1079          * timer.
1080          */
1081         cancel_delayed_work_sync(&per_cpu(slab_reap_work, cpu));
1082         /* Now the cache_reaper is guaranteed to be not running. */
1083         per_cpu(slab_reap_work, cpu).work.func = NULL;
1084         return 0;
1085 }
1086 
1087 #if defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG)
1088 /*
1089  * Drains freelist for a node on each slab cache, used for memory hot-remove.
1090  * Returns -EBUSY if all objects cannot be drained so that the node is not
1091  * removed.
1092  *
1093  * Must hold slab_mutex.
1094  */
1095 static int __meminit drain_cache_node_node(int node)
1096 {
1097         struct kmem_cache *cachep;
1098         int ret = 0;
1099 
1100         list_for_each_entry(cachep, &slab_caches, list) {
1101                 struct kmem_cache_node *n;
1102 
1103                 n = get_node(cachep, node);
1104                 if (!n)
1105                         continue;
1106 
1107                 drain_freelist(cachep, n, INT_MAX);
1108 
1109                 if (!list_empty(&n->slabs_full) ||
1110                     !list_empty(&n->slabs_partial)) {
1111                         ret = -EBUSY;
1112                         break;
1113                 }
1114         }
1115         return ret;
1116 }
1117 
1118 static int __meminit slab_memory_callback(struct notifier_block *self,
1119                                         unsigned long action, void *arg)
1120 {
1121         struct memory_notify *mnb = arg;
1122         int ret = 0;
1123         int nid;
1124 
1125         nid = mnb->status_change_nid;
1126         if (nid < 0)
1127                 goto out;
1128 
1129         switch (action) {
1130         case MEM_GOING_ONLINE:
1131                 mutex_lock(&slab_mutex);
1132                 ret = init_cache_node_node(nid);
1133                 mutex_unlock(&slab_mutex);
1134                 break;
1135         case MEM_GOING_OFFLINE:
1136                 mutex_lock(&slab_mutex);
1137                 ret = drain_cache_node_node(nid);
1138                 mutex_unlock(&slab_mutex);
1139                 break;
1140         case MEM_ONLINE:
1141         case MEM_OFFLINE:
1142         case MEM_CANCEL_ONLINE:
1143         case MEM_CANCEL_OFFLINE:
1144                 break;
1145         }
1146 out:
1147         return notifier_from_errno(ret);
1148 }
1149 #endif /* CONFIG_NUMA && CONFIG_MEMORY_HOTPLUG */
1150 
1151 /*
1152  * swap the static kmem_cache_node with kmalloced memory
1153  */
1154 static void __init init_list(struct kmem_cache *cachep, struct kmem_cache_node *list,
1155                                 int nodeid)
1156 {
1157         struct kmem_cache_node *ptr;
1158 
1159         ptr = kmalloc_node(sizeof(struct kmem_cache_node), GFP_NOWAIT, nodeid);
1160         BUG_ON(!ptr);
1161 
1162         memcpy(ptr, list, sizeof(struct kmem_cache_node));
1163         /*
1164          * Do not assume that spinlocks can be initialized via memcpy:
1165          */
1166         spin_lock_init(&ptr->list_lock);
1167 
1168         MAKE_ALL_LISTS(cachep, ptr, nodeid);
1169         cachep->node[nodeid] = ptr;
1170 }
1171 
1172 /*
1173  * For setting up all the kmem_cache_node for cache whose buffer_size is same as
1174  * size of kmem_cache_node.
1175  */
1176 static void __init set_up_node(struct kmem_cache *cachep, int index)
1177 {
1178         int node;
1179 
1180         for_each_online_node(node) {
1181                 cachep->node[node] = &init_kmem_cache_node[index + node];
1182                 cachep->node[node]->next_reap = jiffies +
1183                     REAPTIMEOUT_NODE +
1184                     ((unsigned long)cachep) % REAPTIMEOUT_NODE;
1185         }
1186 }
1187 
1188 /*
1189  * Initialisation.  Called after the page allocator have been initialised and
1190  * before smp_init().
1191  */
1192 void __init kmem_cache_init(void)
1193 {
1194         int i;
1195 
1196         kmem_cache = &kmem_cache_boot;
1197 
1198         if (!IS_ENABLED(CONFIG_NUMA) || num_possible_nodes() == 1)
1199                 use_alien_caches = 0;
1200 
1201         for (i = 0; i < NUM_INIT_LISTS; i++)
1202                 kmem_cache_node_init(&init_kmem_cache_node[i]);
1203 
1204         /*
1205          * Fragmentation resistance on low memory - only use bigger
1206          * page orders on machines with more than 32MB of memory if
1207          * not overridden on the command line.
1208          */
1209         if (!slab_max_order_set && totalram_pages() > (32 << 20) >> PAGE_SHIFT)
1210                 slab_max_order = SLAB_MAX_ORDER_HI;
1211 
1212         /* Bootstrap is tricky, because several objects are allocated
1213          * from caches that do not exist yet:
1214          * 1) initialize the kmem_cache cache: it contains the struct
1215          *    kmem_cache structures of all caches, except kmem_cache itself:
1216          *    kmem_cache is statically allocated.
1217          *    Initially an __init data area is used for the head array and the
1218          *    kmem_cache_node structures, it's replaced with a kmalloc allocated
1219          *    array at the end of the bootstrap.
1220          * 2) Create the first kmalloc cache.
1221          *    The struct kmem_cache for the new cache is allocated normally.
1222          *    An __init data area is used for the head array.
1223          * 3) Create the remaining kmalloc caches, with minimally sized
1224          *    head arrays.
1225          * 4) Replace the __init data head arrays for kmem_cache and the first
1226          *    kmalloc cache with kmalloc allocated arrays.
1227          * 5) Replace the __init data for kmem_cache_node for kmem_cache and
1228          *    the other cache's with kmalloc allocated memory.
1229          * 6) Resize the head arrays of the kmalloc caches to their final sizes.
1230          */
1231 
1232         /* 1) create the kmem_cache */
1233 
1234         /*
1235          * struct kmem_cache size depends on nr_node_ids & nr_cpu_ids
1236          */
1237         create_boot_cache(kmem_cache, "kmem_cache",
1238                 offsetof(struct kmem_cache, node) +
1239                                   nr_node_ids * sizeof(struct kmem_cache_node *),
1240                                   SLAB_HWCACHE_ALIGN, 0, 0);
1241         list_add(&kmem_cache->list, &slab_caches);
1242         memcg_link_cache(kmem_cache, NULL);
1243         slab_state = PARTIAL;
1244 
1245         /*
1246          * Initialize the caches that provide memory for the  kmem_cache_node
1247          * structures first.  Without this, further allocations will bug.
1248          */
1249         kmalloc_caches[KMALLOC_NORMAL][INDEX_NODE] = create_kmalloc_cache(
1250                                 kmalloc_info[INDEX_NODE].name,
1251                                 kmalloc_size(INDEX_NODE), ARCH_KMALLOC_FLAGS,
1252                                 0, kmalloc_size(INDEX_NODE));
1253         slab_state = PARTIAL_NODE;
1254         setup_kmalloc_cache_index_table();
1255 
1256         slab_early_init = 0;
1257 
1258         /* 5) Replace the bootstrap kmem_cache_node */
1259         {
1260                 int nid;
1261 
1262                 for_each_online_node(nid) {
1263                         init_list(kmem_cache, &init_kmem_cache_node[CACHE_CACHE + nid], nid);
1264 
1265                         init_list(kmalloc_caches[KMALLOC_NORMAL][INDEX_NODE],
1266                                           &init_kmem_cache_node[SIZE_NODE + nid], nid);
1267                 }
1268         }
1269 
1270         create_kmalloc_caches(ARCH_KMALLOC_FLAGS);
1271 }
1272 
1273 void __init kmem_cache_init_late(void)
1274 {
1275         struct kmem_cache *cachep;
1276 
1277         /* 6) resize the head arrays to their final sizes */
1278         mutex_lock(&slab_mutex);
1279         list_for_each_entry(cachep, &slab_caches, list)
1280                 if (enable_cpucache(cachep, GFP_NOWAIT))
1281                         BUG();
1282         mutex_unlock(&slab_mutex);
1283 
1284         /* Done! */
1285         slab_state = FULL;
1286 
1287 #ifdef CONFIG_NUMA
1288         /*
1289          * Register a memory hotplug callback that initializes and frees
1290          * node.
1291          */
1292         hotplug_memory_notifier(slab_memory_callback, SLAB_CALLBACK_PRI);
1293 #endif
1294 
1295         /*
1296          * The reap timers are started later, with a module init call: That part
1297          * of the kernel is not yet operational.
1298          */
1299 }
1300 
1301 static int __init cpucache_init(void)
1302 {
1303         int ret;
1304 
1305         /*
1306          * Register the timers that return unneeded pages to the page allocator
1307          */
1308         ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "SLAB online",
1309                                 slab_online_cpu, slab_offline_cpu);
1310         WARN_ON(ret < 0);
1311 
1312         return 0;
1313 }
1314 __initcall(cpucache_init);
1315 
1316 static noinline void
1317 slab_out_of_memory(struct kmem_cache *cachep, gfp_t gfpflags, int nodeid)
1318 {
1319 #if DEBUG
1320         struct kmem_cache_node *n;
1321         unsigned long flags;
1322         int node;
1323         static DEFINE_RATELIMIT_STATE(slab_oom_rs, DEFAULT_RATELIMIT_INTERVAL,
1324                                       DEFAULT_RATELIMIT_BURST);
1325 
1326         if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slab_oom_rs))
1327                 return;
1328 
1329         pr_warn("SLAB: Unable to allocate memory on node %d, gfp=%#x(%pGg)\n",
1330                 nodeid, gfpflags, &gfpflags);
1331         pr_warn("  cache: %s, object size: %d, order: %d\n",
1332                 cachep->name, cachep->size, cachep->gfporder);
1333 
1334         for_each_kmem_cache_node(cachep, node, n) {
1335                 unsigned long total_slabs, free_slabs, free_objs;
1336 
1337                 spin_lock_irqsave(&n->list_lock, flags);
1338                 total_slabs = n->total_slabs;
1339                 free_slabs = n->free_slabs;
1340                 free_objs = n->free_objects;
1341                 spin_unlock_irqrestore(&n->list_lock, flags);
1342 
1343                 pr_warn("  node %d: slabs: %ld/%ld, objs: %ld/%ld\n",
1344                         node, total_slabs - free_slabs, total_slabs,
1345                         (total_slabs * cachep->num) - free_objs,
1346                         total_slabs * cachep->num);
1347         }
1348 #endif
1349 }
1350 
1351 /*
1352  * Interface to system's page allocator. No need to hold the
1353  * kmem_cache_node ->list_lock.
1354  *
1355  * If we requested dmaable memory, we will get it. Even if we
1356  * did not request dmaable memory, we might get it, but that
1357  * would be relatively rare and ignorable.
1358  */
1359 static struct page *kmem_getpages(struct kmem_cache *cachep, gfp_t flags,
1360                                                                 int nodeid)
1361 {
1362         struct page *page;
1363 
1364         flags |= cachep->allocflags;
1365 
1366         page = __alloc_pages_node(nodeid, flags, cachep->gfporder);
1367         if (!page) {
1368                 slab_out_of_memory(cachep, flags, nodeid);
1369                 return NULL;
1370         }
1371 
1372         if (charge_slab_page(page, flags, cachep->gfporder, cachep)) {
1373                 __free_pages(page, cachep->gfporder);
1374                 return NULL;
1375         }
1376 
1377         __SetPageSlab(page);
1378         /* Record if ALLOC_NO_WATERMARKS was set when allocating the slab */
1379         if (sk_memalloc_socks() && page_is_pfmemalloc(page))
1380                 SetPageSlabPfmemalloc(page);
1381 
1382         return page;
1383 }
1384 
1385 /*
1386  * Interface to system's page release.
1387  */
1388 static void kmem_freepages(struct kmem_cache *cachep, struct page *page)
1389 {
1390         int order = cachep->gfporder;
1391 
1392         BUG_ON(!PageSlab(page));
1393         __ClearPageSlabPfmemalloc(page);
1394         __ClearPageSlab(page);
1395         page_mapcount_reset(page);
1396         page->mapping = NULL;
1397 
1398         if (current->reclaim_state)
1399                 current->reclaim_state->reclaimed_slab += 1 << order;
1400         uncharge_slab_page(page, order, cachep);
1401         __free_pages(page, order);
1402 }
1403 
1404 static void kmem_rcu_free(struct rcu_head *head)
1405 {
1406         struct kmem_cache *cachep;
1407         struct page *page;
1408 
1409         page = container_of(head, struct page, rcu_head);
1410         cachep = page->slab_cache;
1411 
1412         kmem_freepages(cachep, page);
1413 }
1414 
1415 #if DEBUG
1416 static bool is_debug_pagealloc_cache(struct kmem_cache *cachep)
1417 {
1418         if (debug_pagealloc_enabled_static() && OFF_SLAB(cachep) &&
1419                 (cachep->size % PAGE_SIZE) == 0)
1420                 return true;
1421 
1422         return false;
1423 }
1424 
1425 #ifdef CONFIG_DEBUG_PAGEALLOC
1426 static void slab_kernel_map(struct kmem_cache *cachep, void *objp, int map)
1427 {
1428         if (!is_debug_pagealloc_cache(cachep))
1429                 return;
1430 
1431         kernel_map_pages(virt_to_page(objp), cachep->size / PAGE_SIZE, map);
1432 }
1433 
1434 #else
1435 static inline void slab_kernel_map(struct kmem_cache *cachep, void *objp,
1436                                 int map) {}
1437 
1438 #endif
1439 
1440 static void poison_obj(struct kmem_cache *cachep, void *addr, unsigned char val)
1441 {
1442         int size = cachep->object_size;
1443         addr = &((char *)addr)[obj_offset(cachep)];
1444 
1445         memset(addr, val, size);
1446         *(unsigned char *)(addr + size - 1) = POISON_END;
1447 }
1448 
1449 static void dump_line(char *data, int offset, int limit)
1450 {
1451         int i;
1452         unsigned char error = 0;
1453         int bad_count = 0;
1454 
1455         pr_err("%03x: ", offset);
1456         for (i = 0; i < limit; i++) {
1457                 if (data[offset + i] != POISON_FREE) {
1458                         error = data[offset + i];
1459                         bad_count++;
1460                 }
1461         }
1462         print_hex_dump(KERN_CONT, "", 0, 16, 1,
1463                         &data[offset], limit, 1);
1464 
1465         if (bad_count == 1) {
1466                 error ^= POISON_FREE;
1467                 if (!(error & (error - 1))) {
1468                         pr_err("Single bit error detected. Probably bad RAM.\n");
1469 #ifdef CONFIG_X86
1470                         pr_err("Run memtest86+ or a similar memory test tool.\n");
1471 #else
1472                         pr_err("Run a memory test tool.\n");
1473 #endif
1474                 }
1475         }
1476 }
1477 #endif
1478 
1479 #if DEBUG
1480 
1481 static void print_objinfo(struct kmem_cache *cachep, void *objp, int lines)
1482 {
1483         int i, size;
1484         char *realobj;
1485 
1486         if (cachep->flags & SLAB_RED_ZONE) {
1487                 pr_err("Redzone: 0x%llx/0x%llx\n",
1488                        *dbg_redzone1(cachep, objp),
1489                        *dbg_redzone2(cachep, objp));
1490         }
1491 
1492         if (cachep->flags & SLAB_STORE_USER)
1493                 pr_err("Last user: (%pSR)\n", *dbg_userword(cachep, objp));
1494         realobj = (char *)objp + obj_offset(cachep);
1495         size = cachep->object_size;
1496         for (i = 0; i < size && lines; i += 16, lines--) {
1497                 int limit;
1498                 limit = 16;
1499                 if (i + limit > size)
1500                         limit = size - i;
1501                 dump_line(realobj, i, limit);
1502         }
1503 }
1504 
1505 static void check_poison_obj(struct kmem_cache *cachep, void *objp)
1506 {
1507         char *realobj;
1508         int size, i;
1509         int lines = 0;
1510 
1511         if (is_debug_pagealloc_cache(cachep))
1512                 return;
1513 
1514         realobj = (char *)objp + obj_offset(cachep);
1515         size = cachep->object_size;
1516 
1517         for (i = 0; i < size; i++) {
1518                 char exp = POISON_FREE;
1519                 if (i == size - 1)
1520                         exp = POISON_END;
1521                 if (realobj[i] != exp) {
1522                         int limit;
1523                         /* Mismatch ! */
1524                         /* Print header */
1525                         if (lines == 0) {
1526                                 pr_err("Slab corruption (%s): %s start=%px, len=%d\n",
1527                                        print_tainted(), cachep->name,
1528                                        realobj, size);
1529                                 print_objinfo(cachep, objp, 0);
1530                         }
1531                         /* Hexdump the affected line */
1532                         i = (i / 16) * 16;
1533                         limit = 16;
1534                         if (i + limit > size)
1535                                 limit = size - i;
1536                         dump_line(realobj, i, limit);
1537                         i += 16;
1538                         lines++;
1539                         /* Limit to 5 lines */
1540                         if (lines > 5)
1541                                 break;
1542                 }
1543         }
1544         if (lines != 0) {
1545                 /* Print some data about the neighboring objects, if they
1546                  * exist:
1547                  */
1548                 struct page *page = virt_to_head_page(objp);
1549                 unsigned int objnr;
1550 
1551                 objnr = obj_to_index(cachep, page, objp);
1552                 if (objnr) {
1553                         objp = index_to_obj(cachep, page, objnr - 1);
1554                         realobj = (char *)objp + obj_offset(cachep);
1555                         pr_err("Prev obj: start=%px, len=%d\n", realobj, size);
1556                         print_objinfo(cachep, objp, 2);
1557                 }
1558                 if (objnr + 1 < cachep->num) {
1559                         objp = index_to_obj(cachep, page, objnr + 1);
1560                         realobj = (char *)objp + obj_offset(cachep);
1561                         pr_err("Next obj: start=%px, len=%d\n", realobj, size);
1562                         print_objinfo(cachep, objp, 2);
1563                 }
1564         }
1565 }
1566 #endif
1567 
1568 #if DEBUG
1569 static void slab_destroy_debugcheck(struct kmem_cache *cachep,
1570                                                 struct page *page)
1571 {
1572         int i;
1573 
1574         if (OBJFREELIST_SLAB(cachep) && cachep->flags & SLAB_POISON) {
1575                 poison_obj(cachep, page->freelist - obj_offset(cachep),
1576                         POISON_FREE);
1577         }
1578 
1579         for (i = 0; i < cachep->num; i++) {
1580                 void *objp = index_to_obj(cachep, page, i);
1581 
1582                 if (cachep->flags & SLAB_POISON) {
1583                         check_poison_obj(cachep, objp);
1584                         slab_kernel_map(cachep, objp, 1);
1585                 }
1586                 if (cachep->flags & SLAB_RED_ZONE) {
1587                         if (*dbg_redzone1(cachep, objp) != RED_INACTIVE)
1588                                 slab_error(cachep, "start of a freed object was overwritten");
1589                         if (*dbg_redzone2(cachep, objp) != RED_INACTIVE)
1590                                 slab_error(cachep, "end of a freed object was overwritten");
1591                 }
1592         }
1593 }
1594 #else
1595 static void slab_destroy_debugcheck(struct kmem_cache *cachep,
1596                                                 struct page *page)
1597 {
1598 }
1599 #endif
1600 
1601 /**
1602  * slab_destroy - destroy and release all objects in a slab
1603  * @cachep: cache pointer being destroyed
1604  * @page: page pointer being destroyed
1605  *
1606  * Destroy all the objs in a slab page, and release the mem back to the system.
1607  * Before calling the slab page must have been unlinked from the cache. The
1608  * kmem_cache_node ->list_lock is not held/needed.
1609  */
1610 static void slab_destroy(struct kmem_cache *cachep, struct page *page)
1611 {
1612         void *freelist;
1613 
1614         freelist = page->freelist;
1615         slab_destroy_debugcheck(cachep, page);
1616         if (unlikely(cachep->flags & SLAB_TYPESAFE_BY_RCU))
1617                 call_rcu(&page->rcu_head, kmem_rcu_free);
1618         else
1619                 kmem_freepages(cachep, page);
1620 
1621         /*
1622          * From now on, we don't use freelist
1623          * although actual page can be freed in rcu context
1624          */
1625         if (OFF_SLAB(cachep))
1626                 kmem_cache_free(cachep->freelist_cache, freelist);
1627 }
1628 
1629 static void slabs_destroy(struct kmem_cache *cachep, struct list_head *list)
1630 {
1631         struct page *page, *n;
1632 
1633         list_for_each_entry_safe(page, n, list, slab_list) {
1634                 list_del(&page->slab_list);
1635                 slab_destroy(cachep, page);
1636         }
1637 }
1638 
1639 /**
1640  * calculate_slab_order - calculate size (page order) of slabs
1641  * @cachep: pointer to the cache that is being created
1642  * @size: size of objects to be created in this cache.
1643  * @flags: slab allocation flags
1644  *
1645  * Also calculates the number of objects per slab.
1646  *
1647  * This could be made much more intelligent.  For now, try to avoid using
1648  * high order pages for slabs.  When the gfp() functions are more friendly
1649  * towards high-order requests, this should be changed.
1650  *
1651  * Return: number of left-over bytes in a slab
1652  */
1653 static size_t calculate_slab_order(struct kmem_cache *cachep,
1654                                 size_t size, slab_flags_t flags)
1655 {
1656         size_t left_over = 0;
1657         int gfporder;
1658 
1659         for (gfporder = 0; gfporder <= KMALLOC_MAX_ORDER; gfporder++) {
1660                 unsigned int num;
1661                 size_t remainder;
1662 
1663                 num = cache_estimate(gfporder, size, flags, &remainder);
1664                 if (!num)
1665                         continue;
1666 
1667                 /* Can't handle number of objects more than SLAB_OBJ_MAX_NUM */
1668                 if (num > SLAB_OBJ_MAX_NUM)
1669                         break;
1670 
1671                 if (flags & CFLGS_OFF_SLAB) {
1672                         struct kmem_cache *freelist_cache;
1673                         size_t freelist_size;
1674 
1675                         freelist_size = num * sizeof(freelist_idx_t);
1676                         freelist_cache = kmalloc_slab(freelist_size, 0u);
1677                         if (!freelist_cache)
1678                                 continue;
1679 
1680                         /*
1681                          * Needed to avoid possible looping condition
1682                          * in cache_grow_begin()
1683                          */
1684                         if (OFF_SLAB(freelist_cache))
1685                                 continue;
1686 
1687                         /* check if off slab has enough benefit */
1688                         if (freelist_cache->size > cachep->size / 2)
1689                                 continue;
1690                 }
1691 
1692                 /* Found something acceptable - save it away */
1693                 cachep->num = num;
1694                 cachep->gfporder = gfporder;
1695                 left_over = remainder;
1696 
1697                 /*
1698                  * A VFS-reclaimable slab tends to have most allocations
1699                  * as GFP_NOFS and we really don't want to have to be allocating
1700                  * higher-order pages when we are unable to shrink dcache.
1701                  */
1702                 if (flags & SLAB_RECLAIM_ACCOUNT)
1703                         break;
1704 
1705                 /*
1706                  * Large number of objects is good, but very large slabs are
1707                  * currently bad for the gfp()s.
1708                  */
1709                 if (gfporder >= slab_max_order)
1710                         break;
1711 
1712                 /*
1713                  * Acceptable internal fragmentation?
1714                  */
1715                 if (left_over * 8 <= (PAGE_SIZE << gfporder))
1716                         break;
1717         }
1718         return left_over;
1719 }
1720 
1721 static struct array_cache __percpu *alloc_kmem_cache_cpus(
1722                 struct kmem_cache *cachep, int entries, int batchcount)
1723 {
1724         int cpu;
1725         size_t size;
1726         struct array_cache __percpu *cpu_cache;
1727 
1728         size = sizeof(void *) * entries + sizeof(struct array_cache);
1729         cpu_cache = __alloc_percpu(size, sizeof(void *));
1730 
1731         if (!cpu_cache)
1732                 return NULL;
1733 
1734         for_each_possible_cpu(cpu) {
1735                 init_arraycache(per_cpu_ptr(cpu_cache, cpu),
1736                                 entries, batchcount);
1737         }
1738 
1739         return cpu_cache;
1740 }
1741 
1742 static int __ref setup_cpu_cache(struct kmem_cache *cachep, gfp_t gfp)
1743 {
1744         if (slab_state >= FULL)
1745                 return enable_cpucache(cachep, gfp);
1746 
1747         cachep->cpu_cache = alloc_kmem_cache_cpus(cachep, 1, 1);
1748         if (!cachep->cpu_cache)
1749                 return 1;
1750 
1751         if (slab_state == DOWN) {
1752                 /* Creation of first cache (kmem_cache). */
1753                 set_up_node(kmem_cache, CACHE_CACHE);
1754         } else if (slab_state == PARTIAL) {
1755                 /* For kmem_cache_node */
1756                 set_up_node(cachep, SIZE_NODE);
1757         } else {
1758                 int node;
1759 
1760                 for_each_online_node(node) {
1761                         cachep->node[node] = kmalloc_node(
1762                                 sizeof(struct kmem_cache_node), gfp, node);
1763                         BUG_ON(!cachep->node[node]);
1764                         kmem_cache_node_init(cachep->node[node]);
1765                 }
1766         }
1767 
1768         cachep->node[numa_mem_id()]->next_reap =
1769                         jiffies + REAPTIMEOUT_NODE +
1770                         ((unsigned long)cachep) % REAPTIMEOUT_NODE;
1771 
1772         cpu_cache_get(cachep)->avail = 0;
1773         cpu_cache_get(cachep)->limit = BOOT_CPUCACHE_ENTRIES;
1774         cpu_cache_get(cachep)->batchcount = 1;
1775         cpu_cache_get(cachep)->touched = 0;
1776         cachep->batchcount = 1;
1777         cachep->limit = BOOT_CPUCACHE_ENTRIES;
1778         return 0;
1779 }
1780 
1781 slab_flags_t kmem_cache_flags(unsigned int object_size,
1782         slab_flags_t flags, const char *name,
1783         void (*ctor)(void *))
1784 {
1785         return flags;
1786 }
1787 
1788 struct kmem_cache *
1789 __kmem_cache_alias(const char *name, unsigned int size, unsigned int align,
1790                    slab_flags_t flags, void (*ctor)(void *))
1791 {
1792         struct kmem_cache *cachep;
1793 
1794         cachep = find_mergeable(size, align, flags, name, ctor);
1795         if (cachep) {
1796                 cachep->refcount++;
1797 
1798                 /*
1799                  * Adjust the object sizes so that we clear
1800                  * the complete object on kzalloc.
1801                  */
1802                 cachep->object_size = max_t(int, cachep->object_size, size);
1803         }
1804         return cachep;
1805 }
1806 
1807 static bool set_objfreelist_slab_cache(struct kmem_cache *cachep,
1808                         size_t size, slab_flags_t flags)
1809 {
1810         size_t left;
1811 
1812         cachep->num = 0;
1813 
1814         /*
1815          * If slab auto-initialization on free is enabled, store the freelist
1816          * off-slab, so that its contents don't end up in one of the allocated
1817          * objects.
1818          */
1819         if (unlikely(slab_want_init_on_free(cachep)))
1820                 return false;
1821 
1822         if (cachep->ctor || flags & SLAB_TYPESAFE_BY_RCU)
1823                 return false;
1824 
1825         left = calculate_slab_order(cachep, size,
1826                         flags | CFLGS_OBJFREELIST_SLAB);
1827         if (!cachep->num)
1828                 return false;
1829 
1830         if (cachep->num * sizeof(freelist_idx_t) > cachep->object_size)
1831                 return false;
1832 
1833         cachep->colour = left / cachep->colour_off;
1834 
1835         return true;
1836 }
1837 
1838 static bool set_off_slab_cache(struct kmem_cache *cachep,
1839                         size_t size, slab_flags_t flags)
1840 {
1841         size_t left;
1842 
1843         cachep->num = 0;
1844 
1845         /*
1846          * Always use on-slab management when SLAB_NOLEAKTRACE
1847          * to avoid recursive calls into kmemleak.
1848          */
1849         if (flags & SLAB_NOLEAKTRACE)
1850                 return false;
1851 
1852         /*
1853          * Size is large, assume best to place the slab management obj
1854          * off-slab (should allow better packing of objs).
1855          */
1856         left = calculate_slab_order(cachep, size, flags | CFLGS_OFF_SLAB);
1857         if (!cachep->num)
1858                 return false;
1859 
1860         /*
1861          * If the slab has been placed off-slab, and we have enough space then
1862          * move it on-slab. This is at the expense of any extra colouring.
1863          */
1864         if (left >= cachep->num * sizeof(freelist_idx_t))
1865                 return false;
1866 
1867         cachep->colour = left / cachep->colour_off;
1868 
1869         return true;
1870 }
1871 
1872 static bool set_on_slab_cache(struct kmem_cache *cachep,
1873                         size_t size, slab_flags_t flags)
1874 {
1875         size_t left;
1876 
1877         cachep->num = 0;
1878 
1879         left = calculate_slab_order(cachep, size, flags);
1880         if (!cachep->num)
1881                 return false;
1882 
1883         cachep->colour = left / cachep->colour_off;
1884 
1885         return true;
1886 }
1887 
1888 /**
1889  * __kmem_cache_create - Create a cache.
1890  * @cachep: cache management descriptor
1891  * @flags: SLAB flags
1892  *
1893  * Returns a ptr to the cache on success, NULL on failure.
1894  * Cannot be called within a int, but can be interrupted.
1895  * The @ctor is run when new pages are allocated by the cache.
1896  *
1897  * The flags are
1898  *
1899  * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
1900  * to catch references to uninitialised memory.
1901  *
1902  * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
1903  * for buffer overruns.
1904  *
1905  * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
1906  * cacheline.  This can be beneficial if you're counting cycles as closely
1907  * as davem.
1908  *
1909  * Return: a pointer to the created cache or %NULL in case of error
1910  */
1911 int __kmem_cache_create(struct kmem_cache *cachep, slab_flags_t flags)
1912 {
1913         size_t ralign = BYTES_PER_WORD;
1914         gfp_t gfp;
1915         int err;
1916         unsigned int size = cachep->size;
1917 
1918 #if DEBUG
1919 #if FORCED_DEBUG
1920         /*
1921          * Enable redzoning and last user accounting, except for caches with
1922          * large objects, if the increased size would increase the object size
1923          * above the next power of two: caches with object sizes just above a
1924          * power of two have a significant amount of internal fragmentation.
1925          */
1926         if (size < 4096 || fls(size - 1) == fls(size-1 + REDZONE_ALIGN +
1927                                                 2 * sizeof(unsigned long long)))
1928                 flags |= SLAB_RED_ZONE | SLAB_STORE_USER;
1929         if (!(flags & SLAB_TYPESAFE_BY_RCU))
1930                 flags |= SLAB_POISON;
1931 #endif
1932 #endif
1933 
1934         /*
1935          * Check that size is in terms of words.  This is needed to avoid
1936          * unaligned accesses for some archs when redzoning is used, and makes
1937          * sure any on-slab bufctl's are also correctly aligned.
1938          */
1939         size = ALIGN(size, BYTES_PER_WORD);
1940 
1941         if (flags & SLAB_RED_ZONE) {
1942                 ralign = REDZONE_ALIGN;
1943                 /* If redzoning, ensure that the second redzone is suitably
1944                  * aligned, by adjusting the object size accordingly. */
1945                 size = ALIGN(size, REDZONE_ALIGN);
1946         }
1947 
1948         /* 3) caller mandated alignment */
1949         if (ralign < cachep->align) {
1950                 ralign = cachep->align;
1951         }
1952         /* disable debug if necessary */
1953         if (ralign > __alignof__(unsigned long long))
1954                 flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
1955         /*
1956          * 4) Store it.
1957          */
1958         cachep->align = ralign;
1959         cachep->colour_off = cache_line_size();
1960         /* Offset must be a multiple of the alignment. */
1961         if (cachep->colour_off < cachep->align)
1962                 cachep->colour_off = cachep->align;
1963 
1964         if (slab_is_available())
1965                 gfp = GFP_KERNEL;
1966         else
1967                 gfp = GFP_NOWAIT;
1968 
1969 #if DEBUG
1970 
1971         /*
1972          * Both debugging options require word-alignment which is calculated
1973          * into align above.
1974          */
1975         if (flags & SLAB_RED_ZONE) {
1976                 /* add space for red zone words */
1977                 cachep->obj_offset += sizeof(unsigned long long);
1978                 size += 2 * sizeof(unsigned long long);
1979         }
1980         if (flags & SLAB_STORE_USER) {
1981                 /* user store requires one word storage behind the end of
1982                  * the real object. But if the second red zone needs to be
1983                  * aligned to 64 bits, we must allow that much space.
1984                  */
1985                 if (flags & SLAB_RED_ZONE)
1986                         size += REDZONE_ALIGN;
1987                 else
1988                         size += BYTES_PER_WORD;
1989         }
1990 #endif
1991 
1992         kasan_cache_create(cachep, &size, &flags);
1993 
1994         size = ALIGN(size, cachep->align);
1995         /*
1996          * We should restrict the number of objects in a slab to implement
1997          * byte sized index. Refer comment on SLAB_OBJ_MIN_SIZE definition.
1998          */
1999         if (FREELIST_BYTE_INDEX && size < SLAB_OBJ_MIN_SIZE)
2000                 size = ALIGN(SLAB_OBJ_MIN_SIZE, cachep->align);
2001 
2002 #if DEBUG
2003         /*
2004          * To activate debug pagealloc, off-slab management is necessary
2005          * requirement. In early phase of initialization, small sized slab
2006          * doesn't get initialized so it would not be possible. So, we need
2007          * to check size >= 256. It guarantees that all necessary small
2008          * sized slab is initialized in current slab initialization sequence.
2009          */
2010         if (debug_pagealloc_enabled_static() && (flags & SLAB_POISON) &&
2011                 size >= 256 && cachep->object_size > cache_line_size()) {
2012                 if (size < PAGE_SIZE || size % PAGE_SIZE == 0) {
2013                         size_t tmp_size = ALIGN(size, PAGE_SIZE);
2014 
2015                         if (set_off_slab_cache(cachep, tmp_size, flags)) {
2016                                 flags |= CFLGS_OFF_SLAB;
2017                                 cachep->obj_offset += tmp_size - size;
2018                                 size = tmp_size;
2019                                 goto done;
2020                         }
2021                 }
2022         }
2023 #endif
2024 
2025         if (set_objfreelist_slab_cache(cachep, size, flags)) {
2026                 flags |= CFLGS_OBJFREELIST_SLAB;
2027                 goto done;
2028         }
2029 
2030         if (set_off_slab_cache(cachep, size, flags)) {
2031                 flags |= CFLGS_OFF_SLAB;
2032                 goto done;
2033         }
2034 
2035         if (set_on_slab_cache(cachep, size, flags))
2036                 goto done;
2037 
2038         return -E2BIG;
2039 
2040 done:
2041         cachep->freelist_size = cachep->num * sizeof(freelist_idx_t);
2042         cachep->flags = flags;
2043         cachep->allocflags = __GFP_COMP;
2044         if (flags & SLAB_CACHE_DMA)
2045                 cachep->allocflags |= GFP_DMA;
2046         if (flags & SLAB_CACHE_DMA32)
2047                 cachep->allocflags |= GFP_DMA32;
2048         if (flags & SLAB_RECLAIM_ACCOUNT)
2049                 cachep->allocflags |= __GFP_RECLAIMABLE;
2050         cachep->size = size;
2051         cachep->reciprocal_buffer_size = reciprocal_value(size);
2052 
2053 #if DEBUG
2054         /*
2055          * If we're going to use the generic kernel_map_pages()
2056          * poisoning, then it's going to smash the contents of
2057          * the redzone and userword anyhow, so switch them off.
2058          */
2059         if (IS_ENABLED(CONFIG_PAGE_POISONING) &&
2060                 (cachep->flags & SLAB_POISON) &&
2061                 is_debug_pagealloc_cache(cachep))
2062                 cachep->flags &= ~(SLAB_RED_ZONE | SLAB_STORE_USER);
2063 #endif
2064 
2065         if (OFF_SLAB(cachep)) {
2066                 cachep->freelist_cache =
2067                         kmalloc_slab(cachep->freelist_size, 0u);
2068         }
2069 
2070         err = setup_cpu_cache(cachep, gfp);
2071         if (err) {
2072                 __kmem_cache_release(cachep);
2073                 return err;
2074         }
2075 
2076         return 0;
2077 }
2078 
2079 #if DEBUG
2080 static void check_irq_off(void)
2081 {
2082         BUG_ON(!irqs_disabled());
2083 }
2084 
2085 static void check_irq_on(void)
2086 {
2087         BUG_ON(irqs_disabled());
2088 }
2089 
2090 static void check_mutex_acquired(void)
2091 {
2092         BUG_ON(!mutex_is_locked(&slab_mutex));
2093 }
2094 
2095 static void check_spinlock_acquired(struct kmem_cache *cachep)
2096 {
2097 #ifdef CONFIG_SMP
2098         check_irq_off();
2099         assert_spin_locked(&get_node(cachep, numa_mem_id())->list_lock);
2100 #endif
2101 }
2102 
2103 static void check_spinlock_acquired_node(struct kmem_cache *cachep, int node)
2104 {
2105 #ifdef CONFIG_SMP
2106         check_irq_off();
2107         assert_spin_locked(&get_node(cachep, node)->list_lock);
2108 #endif
2109 }
2110 
2111 #else
2112 #define check_irq_off() do { } while(0)
2113 #define check_irq_on()  do { } while(0)
2114 #define check_mutex_acquired()  do { } while(0)
2115 #define check_spinlock_acquired(x) do { } while(0)
2116 #define check_spinlock_acquired_node(x, y) do { } while(0)
2117 #endif
2118 
2119 static void drain_array_locked(struct kmem_cache *cachep, struct array_cache *ac,
2120                                 int node, bool free_all, struct list_head *list)
2121 {
2122         int tofree;
2123 
2124         if (!ac || !ac->avail)
2125                 return;
2126 
2127         tofree = free_all ? ac->avail : (ac->limit + 4) / 5;
2128         if (tofree > ac->avail)
2129                 tofree = (ac->avail + 1) / 2;
2130 
2131         free_block(cachep, ac->entry, tofree, node, list);
2132         ac->avail -= tofree;
2133         memmove(ac->entry, &(ac->entry[tofree]), sizeof(void *) * ac->avail);
2134 }
2135 
2136 static void do_drain(void *arg)
2137 {
2138         struct kmem_cache *cachep = arg;
2139         struct array_cache *ac;
2140         int node = numa_mem_id();
2141         struct kmem_cache_node *n;
2142         LIST_HEAD(list);
2143 
2144         check_irq_off();
2145         ac = cpu_cache_get(cachep);
2146         n = get_node(cachep, node);
2147         spin_lock(&n->list_lock);
2148         free_block(cachep, ac->entry, ac->avail, node, &list);
2149         spin_unlock(&n->list_lock);
2150         slabs_destroy(cachep, &list);
2151         ac->avail = 0;
2152 }
2153 
2154 static void drain_cpu_caches(struct kmem_cache *cachep)
2155 {
2156         struct kmem_cache_node *n;
2157         int node;
2158         LIST_HEAD(list);
2159 
2160         on_each_cpu(do_drain, cachep, 1);
2161         check_irq_on();
2162         for_each_kmem_cache_node(cachep, node, n)
2163                 if (n->alien)
2164                         drain_alien_cache(cachep, n->alien);
2165 
2166         for_each_kmem_cache_node(cachep, node, n) {
2167                 spin_lock_irq(&n->list_lock);
2168                 drain_array_locked(cachep, n->shared, node, true, &list);
2169                 spin_unlock_irq(&n->list_lock);
2170 
2171                 slabs_destroy(cachep, &list);
2172         }
2173 }
2174 
2175 /*
2176  * Remove slabs from the list of free slabs.
2177  * Specify the number of slabs to drain in tofree.
2178  *
2179  * Returns the actual number of slabs released.
2180  */
2181 static int drain_freelist(struct kmem_cache *cache,
2182                         struct kmem_cache_node *n, int tofree)
2183 {
2184         struct list_head *p;
2185         int nr_freed;
2186         struct page *page;
2187 
2188         nr_freed = 0;
2189         while (nr_freed < tofree && !list_empty(&n->slabs_free)) {
2190 
2191                 spin_lock_irq(&n->list_lock);
2192                 p = n->slabs_free.prev;
2193                 if (p == &n->slabs_free) {
2194                         spin_unlock_irq(&n->list_lock);
2195                         goto out;
2196                 }
2197 
2198                 page = list_entry(p, struct page, slab_list);
2199                 list_del(&page->slab_list);
2200                 n->free_slabs--;
2201                 n->total_slabs--;
2202                 /*
2203                  * Safe to drop the lock. The slab is no longer linked
2204                  * to the cache.
2205                  */
2206                 n->free_objects -= cache->num;
2207                 spin_unlock_irq(&n->list_lock);
2208                 slab_destroy(cache, page);
2209                 nr_freed++;
2210         }
2211 out:
2212         return nr_freed;
2213 }
2214 
2215 bool __kmem_cache_empty(struct kmem_cache *s)
2216 {
2217         int node;
2218         struct kmem_cache_node *n;
2219 
2220         for_each_kmem_cache_node(s, node, n)
2221                 if (!list_empty(&n->slabs_full) ||
2222                     !list_empty(&n->slabs_partial))
2223                         return false;
2224         return true;
2225 }
2226 
2227 int __kmem_cache_shrink(struct kmem_cache *cachep)
2228 {
2229         int ret = 0;
2230         int node;
2231         struct kmem_cache_node *n;
2232 
2233         drain_cpu_caches(cachep);
2234 
2235         check_irq_on();
2236         for_each_kmem_cache_node(cachep, node, n) {
2237                 drain_freelist(cachep, n, INT_MAX);
2238 
2239                 ret += !list_empty(&n->slabs_full) ||
2240                         !list_empty(&n->slabs_partial);
2241         }
2242         return (ret ? 1 : 0);
2243 }
2244 
2245 #ifdef CONFIG_MEMCG
2246 void __kmemcg_cache_deactivate(struct kmem_cache *cachep)
2247 {
2248         __kmem_cache_shrink(cachep);
2249 }
2250 
2251 void __kmemcg_cache_deactivate_after_rcu(struct kmem_cache *s)
2252 {
2253 }
2254 #endif
2255 
2256 int __kmem_cache_shutdown(struct kmem_cache *cachep)
2257 {
2258         return __kmem_cache_shrink(cachep);
2259 }
2260 
2261 void __kmem_cache_release(struct kmem_cache *cachep)
2262 {
2263         int i;
2264         struct kmem_cache_node *n;
2265 
2266         cache_random_seq_destroy(cachep);
2267 
2268         free_percpu(cachep->cpu_cache);
2269 
2270         /* NUMA: free the node structures */
2271         for_each_kmem_cache_node(cachep, i, n) {
2272                 kfree(n->shared);
2273                 free_alien_cache(n->alien);
2274                 kfree(n);
2275                 cachep->node[i] = NULL;
2276         }
2277 }
2278 
2279 /*
2280  * Get the memory for a slab management obj.
2281  *
2282  * For a slab cache when the slab descriptor is off-slab, the
2283  * slab descriptor can't come from the same cache which is being created,
2284  * Because if it is the case, that means we defer the creation of
2285  * the kmalloc_{dma,}_cache of size sizeof(slab descriptor) to this point.
2286  * And we eventually call down to __kmem_cache_create(), which
2287  * in turn looks up in the kmalloc_{dma,}_caches for the disired-size one.
2288  * This is a "chicken-and-egg" problem.
2289  *
2290  * So the off-slab slab descriptor shall come from the kmalloc_{dma,}_caches,
2291  * which are all initialized during kmem_cache_init().
2292  */
2293 static void *alloc_slabmgmt(struct kmem_cache *cachep,
2294                                    struct page *page, int colour_off,
2295                                    gfp_t local_flags, int nodeid)
2296 {
2297         void *freelist;
2298         void *addr = page_address(page);
2299 
2300         page->s_mem = addr + colour_off;
2301         page->active = 0;
2302 
2303         if (OBJFREELIST_SLAB(cachep))
2304                 freelist = NULL;
2305         else if (OFF_SLAB(cachep)) {
2306                 /* Slab management obj is off-slab. */
2307                 freelist = kmem_cache_alloc_node(cachep->freelist_cache,
2308                                               local_flags, nodeid);
2309                 if (!freelist)
2310                         return NULL;
2311         } else {
2312                 /* We will use last bytes at the slab for freelist */
2313                 freelist = addr + (PAGE_SIZE << cachep->gfporder) -
2314                                 cachep->freelist_size;
2315         }
2316 
2317         return freelist;
2318 }
2319 
2320 static inline freelist_idx_t get_free_obj(struct page *page, unsigned int idx)
2321 {
2322         return ((freelist_idx_t *)page->freelist)[idx];
2323 }
2324 
2325 static inline void set_free_obj(struct page *page,
2326                                         unsigned int idx, freelist_idx_t val)
2327 {
2328         ((freelist_idx_t *)(page->freelist))[idx] = val;
2329 }
2330 
2331 static void cache_init_objs_debug(struct kmem_cache *cachep, struct page *page)
2332 {
2333 #if DEBUG
2334         int i;
2335 
2336         for (i = 0; i < cachep->num; i++) {
2337                 void *objp = index_to_obj(cachep, page, i);
2338 
2339                 if (cachep->flags & SLAB_STORE_USER)
2340                         *dbg_userword(cachep, objp) = NULL;
2341 
2342                 if (cachep->flags & SLAB_RED_ZONE) {
2343                         *dbg_redzone1(cachep, objp) = RED_INACTIVE;
2344                         *dbg_redzone2(cachep, objp) = RED_INACTIVE;
2345                 }
2346                 /*
2347                  * Constructors are not allowed to allocate memory from the same
2348                  * cache which they are a constructor for.  Otherwise, deadlock.
2349                  * They must also be threaded.
2350                  */
2351                 if (cachep->ctor && !(cachep->flags & SLAB_POISON)) {
2352                         kasan_unpoison_object_data(cachep,
2353                                                    objp + obj_offset(cachep));
2354                         cachep->ctor(objp + obj_offset(cachep));
2355                         kasan_poison_object_data(
2356                                 cachep, objp + obj_offset(cachep));
2357                 }
2358 
2359                 if (cachep->flags & SLAB_RED_ZONE) {
2360                         if (*dbg_redzone2(cachep, objp) != RED_INACTIVE)
2361                                 slab_error(cachep, "constructor overwrote the end of an object");
2362                         if (*dbg_redzone1(cachep, objp) != RED_INACTIVE)
2363                                 slab_error(cachep, "constructor overwrote the start of an object");
2364                 }
2365                 /* need to poison the objs? */
2366                 if (cachep->flags & SLAB_POISON) {
2367                         poison_obj(cachep, objp, POISON_FREE);
2368                         slab_kernel_map(cachep, objp, 0);
2369                 }
2370         }
2371 #endif
2372 }
2373 
2374 #ifdef CONFIG_SLAB_FREELIST_RANDOM
2375 /* Hold information during a freelist initialization */
2376 union freelist_init_state {
2377         struct {
2378                 unsigned int pos;
2379                 unsigned int *list;
2380                 unsigned int count;
2381         };
2382         struct rnd_state rnd_state;
2383 };
2384 
2385 /*
2386  * Initialize the state based on the randomization methode available.
2387  * return true if the pre-computed list is available, false otherwize.
2388  */
2389 static bool freelist_state_initialize(union freelist_init_state *state,
2390                                 struct kmem_cache *cachep,
2391                                 unsigned int count)
2392 {
2393         bool ret;
2394         unsigned int rand;
2395 
2396         /* Use best entropy available to define a random shift */
2397         rand = get_random_int();
2398 
2399         /* Use a random state if the pre-computed list is not available */
2400         if (!cachep->random_seq) {
2401                 prandom_seed_state(&state->rnd_state, rand);
2402                 ret = false;
2403         } else {
2404                 state->list = cachep->random_seq;
2405                 state->count = count;
2406                 state->pos = rand % count;
2407                 ret = true;
2408         }
2409         return ret;
2410 }
2411 
2412 /* Get the next entry on the list and randomize it using a random shift */
2413 static freelist_idx_t next_random_slot(union freelist_init_state *state)
2414 {
2415         if (state->pos >= state->count)
2416                 state->pos = 0;
2417         return state->list[state->pos++];
2418 }
2419 
2420 /* Swap two freelist entries */
2421 static void swap_free_obj(struct page *page, unsigned int a, unsigned int b)
2422 {
2423         swap(((freelist_idx_t *)page->freelist)[a],
2424                 ((freelist_idx_t *)page->freelist)[b]);
2425 }
2426 
2427 /*
2428  * Shuffle the freelist initialization state based on pre-computed lists.
2429  * return true if the list was successfully shuffled, false otherwise.
2430  */
2431 static bool shuffle_freelist(struct kmem_cache *cachep, struct page *page)
2432 {
2433         unsigned int objfreelist = 0, i, rand, count = cachep->num;
2434         union freelist_init_state state;
2435         bool precomputed;
2436 
2437         if (count < 2)
2438                 return false;
2439 
2440         precomputed = freelist_state_initialize(&state, cachep, count);
2441 
2442         /* Take a random entry as the objfreelist */
2443         if (OBJFREELIST_SLAB(cachep)) {
2444                 if (!precomputed)
2445                         objfreelist = count - 1;
2446                 else
2447                         objfreelist = next_random_slot(&state);
2448                 page->freelist = index_to_obj(cachep, page, objfreelist) +
2449                                                 obj_offset(cachep);
2450                 count--;
2451         }
2452 
2453         /*
2454          * On early boot, generate the list dynamically.
2455          * Later use a pre-computed list for speed.
2456          */
2457         if (!precomputed) {
2458                 for (i = 0; i < count; i++)
2459                         set_free_obj(page, i, i);
2460 
2461                 /* Fisher-Yates shuffle */
2462                 for (i = count - 1; i > 0; i--) {
2463                         rand = prandom_u32_state(&state.rnd_state);
2464                         rand %= (i + 1);
2465                         swap_free_obj(page, i, rand);
2466                 }
2467         } else {
2468                 for (i = 0; i < count; i++)
2469                         set_free_obj(page, i, next_random_slot(&state));
2470         }
2471 
2472         if (OBJFREELIST_SLAB(cachep))
2473                 set_free_obj(page, cachep->num - 1, objfreelist);
2474 
2475         return true;
2476 }
2477 #else
2478 static inline bool shuffle_freelist(struct kmem_cache *cachep,
2479                                 struct page *page)
2480 {
2481         return false;
2482 }
2483 #endif /* CONFIG_SLAB_FREELIST_RANDOM */
2484 
2485 static void cache_init_objs(struct kmem_cache *cachep,
2486                             struct page *page)
2487 {
2488         int i;
2489         void *objp;
2490         bool shuffled;
2491 
2492         cache_init_objs_debug(cachep, page);
2493 
2494         /* Try to randomize the freelist if enabled */
2495         shuffled = shuffle_freelist(cachep, page);
2496 
2497         if (!shuffled && OBJFREELIST_SLAB(cachep)) {
2498                 page->freelist = index_to_obj(cachep, page, cachep->num - 1) +
2499                                                 obj_offset(cachep);
2500         }
2501 
2502         for (i = 0; i < cachep->num; i++) {
2503                 objp = index_to_obj(cachep, page, i);
2504                 objp = kasan_init_slab_obj(cachep, objp);
2505 
2506                 /* constructor could break poison info */
2507                 if (DEBUG == 0 && cachep->ctor) {
2508                         kasan_unpoison_object_data(cachep, objp);
2509                         cachep->ctor(objp);
2510                         kasan_poison_object_data(cachep, objp);
2511                 }
2512 
2513                 if (!shuffled)
2514                         set_free_obj(page, i, i);
2515         }
2516 }
2517 
2518 static void *slab_get_obj(struct kmem_cache *cachep, struct page *page)
2519 {
2520         void *objp;
2521 
2522         objp = index_to_obj(cachep, page, get_free_obj(page, page->active));
2523         page->active++;
2524 
2525         return objp;
2526 }
2527 
2528 static void slab_put_obj(struct kmem_cache *cachep,
2529                         struct page *page, void *objp)
2530 {
2531         unsigned int objnr = obj_to_index(cachep, page, objp);
2532 #if DEBUG
2533         unsigned int i;
2534 
2535         /* Verify double free bug */
2536         for (i = page->active; i < cachep->num; i++) {
2537                 if (get_free_obj(page, i) == objnr) {
2538                         pr_err("slab: double free detected in cache '%s', objp %px\n",
2539                                cachep->name, objp);
2540                         BUG();
2541                 }
2542         }
2543 #endif
2544         page->active--;
2545         if (!page->freelist)
2546                 page->freelist = objp + obj_offset(cachep);
2547 
2548         set_free_obj(page, page->active, objnr);
2549 }
2550 
2551 /*
2552  * Map pages beginning at addr to the given cache and slab. This is required
2553  * for the slab allocator to be able to lookup the cache and slab of a
2554  * virtual address for kfree, ksize, and slab debugging.
2555  */
2556 static void slab_map_pages(struct kmem_cache *cache, struct page *page,
2557                            void *freelist)
2558 {
2559         page->slab_cache = cache;
2560         page->freelist = freelist;
2561 }
2562 
2563 /*
2564  * Grow (by 1) the number of slabs within a cache.  This is called by
2565  * kmem_cache_alloc() when there are no active objs left in a cache.
2566  */
2567 static struct page *cache_grow_begin(struct kmem_cache *cachep,
2568                                 gfp_t flags, int nodeid)
2569 {
2570         void *freelist;
2571         size_t offset;
2572         gfp_t local_flags;
2573         int page_node;
2574         struct kmem_cache_node *n;
2575         struct page *page;
2576 
2577         /*
2578          * Be lazy and only check for valid flags here,  keeping it out of the
2579          * critical path in kmem_cache_alloc().
2580          */
2581         if (unlikely(flags & GFP_SLAB_BUG_MASK)) {
2582                 gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK;
2583                 flags &= ~GFP_SLAB_BUG_MASK;
2584                 pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n",
2585                                 invalid_mask, &invalid_mask, flags, &flags);
2586                 dump_stack();
2587         }
2588         WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO));
2589         local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
2590 
2591         check_irq_off();
2592         if (gfpflags_allow_blocking(local_flags))
2593                 local_irq_enable();
2594 
2595         /*
2596          * Get mem for the objs.  Attempt to allocate a physical page from
2597          * 'nodeid'.
2598          */
2599         page = kmem_getpages(cachep, local_flags, nodeid);
2600         if (!page)
2601                 goto failed;
2602 
2603         page_node = page_to_nid(page);
2604         n = get_node(cachep, page_node);
2605 
2606         /* Get colour for the slab, and cal the next value. */
2607         n->colour_next++;
2608         if (n->colour_next >= cachep->colour)
2609                 n->colour_next = 0;
2610 
2611         offset = n->colour_next;
2612         if (offset >= cachep->colour)
2613                 offset = 0;
2614 
2615         offset *= cachep->colour_off;
2616 
2617         /*
2618          * Call kasan_poison_slab() before calling alloc_slabmgmt(), so
2619          * page_address() in the latter returns a non-tagged pointer,
2620          * as it should be for slab pages.
2621          */
2622         kasan_poison_slab(page);
2623 
2624         /* Get slab management. */
2625         freelist = alloc_slabmgmt(cachep, page, offset,
2626                         local_flags & ~GFP_CONSTRAINT_MASK, page_node);
2627         if (OFF_SLAB(cachep) && !freelist)
2628                 goto opps1;
2629 
2630         slab_map_pages(cachep, page, freelist);
2631 
2632         cache_init_objs(cachep, page);
2633 
2634         if (gfpflags_allow_blocking(local_flags))
2635                 local_irq_disable();
2636 
2637         return page;
2638 
2639 opps1:
2640         kmem_freepages(cachep, page);
2641 failed:
2642         if (gfpflags_allow_blocking(local_flags))
2643                 local_irq_disable();
2644         return NULL;
2645 }
2646 
2647 static void cache_grow_end(struct kmem_cache *cachep, struct page *page)
2648 {
2649         struct kmem_cache_node *n;
2650         void *list = NULL;
2651 
2652         check_irq_off();
2653 
2654         if (!page)
2655                 return;
2656 
2657         INIT_LIST_HEAD(&page->slab_list);
2658         n = get_node(cachep, page_to_nid(page));
2659 
2660         spin_lock(&n->list_lock);
2661         n->total_slabs++;
2662         if (!page->active) {
2663                 list_add_tail(&page->slab_list, &n->slabs_free);
2664                 n->free_slabs++;
2665         } else
2666                 fixup_slab_list(cachep, n, page, &list);
2667 
2668         STATS_INC_GROWN(cachep);
2669         n->free_objects += cachep->num - page->active;
2670         spin_unlock(&n->list_lock);
2671 
2672         fixup_objfreelist_debug(cachep, &list);
2673 }
2674 
2675 #if DEBUG
2676 
2677 /*
2678  * Perform extra freeing checks:
2679  * - detect bad pointers.
2680  * - POISON/RED_ZONE checking
2681  */
2682 static void kfree_debugcheck(const void *objp)
2683 {
2684         if (!virt_addr_valid(objp)) {
2685                 pr_err("kfree_debugcheck: out of range ptr %lxh\n",
2686                        (unsigned long)objp);
2687                 BUG();
2688         }
2689 }
2690 
2691 static inline void verify_redzone_free(struct kmem_cache *cache, void *obj)
2692 {
2693         unsigned long long redzone1, redzone2;
2694 
2695         redzone1 = *dbg_redzone1(cache, obj);
2696         redzone2 = *dbg_redzone2(cache, obj);
2697 
2698         /*
2699          * Redzone is ok.
2700          */
2701         if (redzone1 == RED_ACTIVE && redzone2 == RED_ACTIVE)
2702                 return;
2703 
2704         if (redzone1 == RED_INACTIVE && redzone2 == RED_INACTIVE)
2705                 slab_error(cache, "double free detected");
2706         else
2707                 slab_error(cache, "memory outside object was overwritten");
2708 
2709         pr_err("%px: redzone 1:0x%llx, redzone 2:0x%llx\n",
2710                obj, redzone1, redzone2);
2711 }
2712 
2713 static void *cache_free_debugcheck(struct kmem_cache *cachep, void *objp,
2714                                    unsigned long caller)
2715 {
2716         unsigned int objnr;
2717         struct page *page;
2718 
2719         BUG_ON(virt_to_cache(objp) != cachep);
2720 
2721         objp -= obj_offset(cachep);
2722         kfree_debugcheck(objp);
2723         page = virt_to_head_page(objp);
2724 
2725         if (cachep->flags & SLAB_RED_ZONE) {
2726                 verify_redzone_free(cachep, objp);
2727                 *dbg_redzone1(cachep, objp) = RED_INACTIVE;
2728                 *dbg_redzone2(cachep, objp) = RED_INACTIVE;
2729         }
2730         if (cachep->flags & SLAB_STORE_USER)
2731                 *dbg_userword(cachep, objp) = (void *)caller;
2732 
2733         objnr = obj_to_index(cachep, page, objp);
2734 
2735         BUG_ON(objnr >= cachep->num);
2736         BUG_ON(objp != index_to_obj(cachep, page, objnr));
2737 
2738         if (cachep->flags & SLAB_POISON) {
2739                 poison_obj(cachep, objp, POISON_FREE);
2740                 slab_kernel_map(cachep, objp, 0);
2741         }
2742         return objp;
2743 }
2744 
2745 #else
2746 #define kfree_debugcheck(x) do { } while(0)
2747 #define cache_free_debugcheck(x,objp,z) (objp)
2748 #endif
2749 
2750 static inline void fixup_objfreelist_debug(struct kmem_cache *cachep,
2751                                                 void **list)
2752 {
2753 #if DEBUG
2754         void *next = *list;
2755         void *objp;
2756 
2757         while (next) {
2758                 objp = next - obj_offset(cachep);
2759                 next = *(void **)next;
2760                 poison_obj(cachep, objp, POISON_FREE);
2761         }
2762 #endif
2763 }
2764 
2765 static inline void fixup_slab_list(struct kmem_cache *cachep,
2766                                 struct kmem_cache_node *n, struct page *page,
2767                                 void **list)
2768 {
2769         /* move slabp to correct slabp list: */
2770         list_del(&page->slab_list);
2771         if (page->active == cachep->num) {
2772                 list_add(&page->slab_list, &n->slabs_full);
2773                 if (OBJFREELIST_SLAB(cachep)) {
2774 #if DEBUG
2775                         /* Poisoning will be done without holding the lock */
2776                         if (cachep->flags & SLAB_POISON) {
2777                                 void **objp = page->freelist;
2778 
2779                                 *objp = *list;
2780                                 *list = objp;
2781                         }
2782 #endif
2783                         page->freelist = NULL;
2784                 }
2785         } else
2786                 list_add(&page->slab_list, &n->slabs_partial);
2787 }
2788 
2789 /* Try to find non-pfmemalloc slab if needed */
2790 static noinline struct page *get_valid_first_slab(struct kmem_cache_node *n,
2791                                         struct page *page, bool pfmemalloc)
2792 {
2793         if (!page)
2794                 return NULL;
2795 
2796         if (pfmemalloc)
2797                 return page;
2798 
2799         if (!PageSlabPfmemalloc(page))
2800                 return page;
2801 
2802         /* No need to keep pfmemalloc slab if we have enough free objects */
2803         if (n->free_objects > n->free_limit) {
2804                 ClearPageSlabPfmemalloc(page);
2805                 return page;
2806         }
2807 
2808         /* Move pfmemalloc slab to the end of list to speed up next search */
2809         list_del(&page->slab_list);
2810         if (!page->active) {
2811                 list_add_tail(&page->slab_list, &n->slabs_free);
2812                 n->free_slabs++;
2813         } else
2814                 list_add_tail(&page->slab_list, &n->slabs_partial);
2815 
2816         list_for_each_entry(page, &n->slabs_partial, slab_list) {
2817                 if (!PageSlabPfmemalloc(page))
2818                         return page;
2819         }
2820 
2821         n->free_touched = 1;
2822         list_for_each_entry(page, &n->slabs_free, slab_list) {
2823                 if (!PageSlabPfmemalloc(page)) {
2824                         n->free_slabs--;
2825                         return page;
2826                 }
2827         }
2828 
2829         return NULL;
2830 }
2831 
2832 static struct page *get_first_slab(struct kmem_cache_node *n, bool pfmemalloc)
2833 {
2834         struct page *page;
2835 
2836         assert_spin_locked(&n->list_lock);
2837         page = list_first_entry_or_null(&n->slabs_partial, struct page,
2838                                         slab_list);
2839         if (!page) {
2840                 n->free_touched = 1;
2841                 page = list_first_entry_or_null(&n->slabs_free, struct page,
2842                                                 slab_list);
2843                 if (page)
2844                         n->free_slabs--;
2845         }
2846 
2847         if (sk_memalloc_socks())
2848                 page = get_valid_first_slab(n, page, pfmemalloc);
2849 
2850         return page;
2851 }
2852 
2853 static noinline void *cache_alloc_pfmemalloc(struct kmem_cache *cachep,
2854                                 struct kmem_cache_node *n, gfp_t flags)
2855 {
2856         struct page *page;
2857         void *obj;
2858         void *list = NULL;
2859 
2860         if (!gfp_pfmemalloc_allowed(flags))
2861                 return NULL;
2862 
2863         spin_lock(&n->list_lock);
2864         page = get_first_slab(n, true);
2865         if (!page) {
2866                 spin_unlock(&n->list_lock);
2867                 return NULL;
2868         }
2869 
2870         obj = slab_get_obj(cachep, page);
2871         n->free_objects--;
2872 
2873         fixup_slab_list(cachep, n, page, &list);
2874 
2875         spin_unlock(&n->list_lock);
2876         fixup_objfreelist_debug(cachep, &list);
2877 
2878         return obj;
2879 }
2880 
2881 /*
2882  * Slab list should be fixed up by fixup_slab_list() for existing slab
2883  * or cache_grow_end() for new slab
2884  */
2885 static __always_inline int alloc_block(struct kmem_cache *cachep,
2886                 struct array_cache *ac, struct page *page, int batchcount)
2887 {
2888         /*
2889          * There must be at least one object available for
2890          * allocation.
2891          */
2892         BUG_ON(page->active >= cachep->num);
2893 
2894         while (page->active < cachep->num && batchcount--) {
2895                 STATS_INC_ALLOCED(cachep);
2896                 STATS_INC_ACTIVE(cachep);
2897                 STATS_SET_HIGH(cachep);
2898 
2899                 ac->entry[ac->avail++] = slab_get_obj(cachep, page);
2900         }
2901 
2902         return batchcount;
2903 }
2904 
2905 static void *cache_alloc_refill(struct kmem_cache *cachep, gfp_t flags)
2906 {
2907         int batchcount;
2908         struct kmem_cache_node *n;
2909         struct array_cache *ac, *shared;
2910         int node;
2911         void *list = NULL;
2912         struct page *page;
2913 
2914         check_irq_off();
2915         node = numa_mem_id();
2916 
2917         ac = cpu_cache_get(cachep);
2918         batchcount = ac->batchcount;
2919         if (!ac->touched && batchcount > BATCHREFILL_LIMIT) {
2920                 /*
2921                  * If there was little recent activity on this cache, then
2922                  * perform only a partial refill.  Otherwise we could generate
2923                  * refill bouncing.
2924                  */
2925                 batchcount = BATCHREFILL_LIMIT;
2926         }
2927         n = get_node(cachep, node);
2928 
2929         BUG_ON(ac->avail > 0 || !n);
2930         shared = READ_ONCE(n->shared);
2931         if (!n->free_objects && (!shared || !shared->avail))
2932                 goto direct_grow;
2933 
2934         spin_lock(&n->list_lock);
2935         shared = READ_ONCE(n->shared);
2936 
2937         /* See if we can refill from the shared array */
2938         if (shared && transfer_objects(ac, shared, batchcount)) {
2939                 shared->touched = 1;
2940                 goto alloc_done;
2941         }
2942 
2943         while (batchcount > 0) {
2944                 /* Get slab alloc is to come from. */
2945                 page = get_first_slab(n, false);
2946                 if (!page)
2947                         goto must_grow;
2948 
2949                 check_spinlock_acquired(cachep);
2950 
2951                 batchcount = alloc_block(cachep, ac, page, batchcount);
2952                 fixup_slab_list(cachep, n, page, &list);
2953         }
2954 
2955 must_grow:
2956         n->free_objects -= ac->avail;
2957 alloc_done:
2958         spin_unlock(&n->list_lock);
2959         fixup_objfreelist_debug(cachep, &list);
2960 
2961 direct_grow:
2962         if (unlikely(!ac->avail)) {
2963                 /* Check if we can use obj in pfmemalloc slab */
2964                 if (sk_memalloc_socks()) {
2965                         void *obj = cache_alloc_pfmemalloc(cachep, n, flags);
2966 
2967                         if (obj)
2968                                 return obj;
2969                 }
2970 
2971                 page = cache_grow_begin(cachep, gfp_exact_node(flags), node);
2972 
2973                 /*
2974                  * cache_grow_begin() can reenable interrupts,
2975                  * then ac could change.
2976                  */
2977                 ac = cpu_cache_get(cachep);
2978                 if (!ac->avail && page)
2979                         alloc_block(cachep, ac, page, batchcount);
2980                 cache_grow_end(cachep, page);
2981 
2982                 if (!ac->avail)
2983                         return NULL;
2984         }
2985         ac->touched = 1;
2986 
2987         return ac->entry[--ac->avail];
2988 }
2989 
2990 static inline void cache_alloc_debugcheck_before(struct kmem_cache *cachep,
2991                                                 gfp_t flags)
2992 {
2993         might_sleep_if(gfpflags_allow_blocking(flags));
2994 }
2995 
2996 #if DEBUG
2997 static void *cache_alloc_debugcheck_after(struct kmem_cache *cachep,
2998                                 gfp_t flags, void *objp, unsigned long caller)
2999 {
3000         WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO));
3001         if (!objp)
3002                 return objp;
3003         if (cachep->flags & SLAB_POISON) {
3004                 check_poison_obj(cachep, objp);
3005                 slab_kernel_map(cachep, objp, 1);
3006                 poison_obj(cachep, objp, POISON_INUSE);
3007         }
3008         if (cachep->flags & SLAB_STORE_USER)
3009                 *dbg_userword(cachep, objp) = (void *)caller;
3010 
3011         if (cachep->flags & SLAB_RED_ZONE) {
3012                 if (*dbg_redzone1(cachep, objp) != RED_INACTIVE ||
3013                                 *dbg_redzone2(cachep, objp) != RED_INACTIVE) {
3014                         slab_error(cachep, "double free, or memory outside object was overwritten");
3015                         pr_err("%px: redzone 1:0x%llx, redzone 2:0x%llx\n",
3016                                objp, *dbg_redzone1(cachep, objp),
3017                                *dbg_redzone2(cachep, objp));
3018                 }
3019                 *dbg_redzone1(cachep, objp) = RED_ACTIVE;
3020                 *dbg_redzone2(cachep, objp) = RED_ACTIVE;
3021         }
3022 
3023         objp += obj_offset(cachep);
3024         if (cachep->ctor && cachep->flags & SLAB_POISON)
3025                 cachep->ctor(objp);
3026         if (ARCH_SLAB_MINALIGN &&
3027             ((unsigned long)objp & (ARCH_SLAB_MINALIGN-1))) {
3028                 pr_err("0x%px: not aligned to ARCH_SLAB_MINALIGN=%d\n",
3029                        objp, (int)ARCH_SLAB_MINALIGN);
3030         }
3031         return objp;
3032 }
3033 #else
3034 #define cache_alloc_debugcheck_after(a,b,objp,d) (objp)
3035 #endif
3036 
3037 static inline void *____cache_alloc(struct kmem_cache *cachep, gfp_t flags)
3038 {
3039         void *objp;
3040         struct array_cache *ac;
3041 
3042         check_irq_off();
3043 
3044         ac = cpu_cache_get(cachep);
3045         if (likely(ac->avail)) {
3046                 ac->touched = 1;
3047                 objp = ac->entry[--ac->avail];
3048 
3049                 STATS_INC_ALLOCHIT(cachep);
3050                 goto out;
3051         }
3052 
3053         STATS_INC_ALLOCMISS(cachep);
3054         objp = cache_alloc_refill(cachep, flags);
3055         /*
3056          * the 'ac' may be updated by cache_alloc_refill(),
3057          * and kmemleak_erase() requires its correct value.
3058          */
3059         ac = cpu_cache_get(cachep);
3060 
3061 out:
3062         /*
3063          * To avoid a false negative, if an object that is in one of the
3064          * per-CPU caches is leaked, we need to make sure kmemleak doesn't
3065          * treat the array pointers as a reference to the object.
3066          */
3067         if (objp)
3068                 kmemleak_erase(&ac->entry[ac->avail]);
3069         return objp;
3070 }
3071 
3072 #ifdef CONFIG_NUMA
3073 /*
3074  * Try allocating on another node if PFA_SPREAD_SLAB is a mempolicy is set.
3075  *
3076  * If we are in_interrupt, then process context, including cpusets and
3077  * mempolicy, may not apply and should not be used for allocation policy.
3078  */
3079 static void *alternate_node_alloc(struct kmem_cache *cachep, gfp_t flags)
3080 {
3081         int nid_alloc, nid_here;
3082 
3083         if (in_interrupt() || (flags & __GFP_THISNODE))
3084                 return NULL;
3085         nid_alloc = nid_here = numa_mem_id();
3086         if (cpuset_do_slab_mem_spread() && (cachep->flags & SLAB_MEM_SPREAD))
3087                 nid_alloc = cpuset_slab_spread_node();
3088         else if (current->mempolicy)
3089                 nid_alloc = mempolicy_slab_node();
3090         if (nid_alloc != nid_here)
3091                 return ____cache_alloc_node(cachep, flags, nid_alloc);
3092         return NULL;
3093 }
3094 
3095 /*
3096  * Fallback function if there was no memory available and no objects on a
3097  * certain node and fall back is permitted. First we scan all the
3098  * available node for available objects. If that fails then we
3099  * perform an allocation without specifying a node. This allows the page
3100  * allocator to do its reclaim / fallback magic. We then insert the
3101  * slab into the proper nodelist and then allocate from it.
3102  */
3103 static void *fallback_alloc(struct kmem_cache *cache, gfp_t flags)
3104 {
3105         struct zonelist *zonelist;
3106         struct zoneref *z;
3107         struct zone *zone;
3108         enum zone_type high_zoneidx = gfp_zone(flags);
3109         void *obj = NULL;
3110         struct page *page;
3111         int nid;
3112         unsigned int cpuset_mems_cookie;
3113 
3114         if (flags & __GFP_THISNODE)
3115                 return NULL;
3116 
3117 retry_cpuset:
3118         cpuset_mems_cookie = read_mems_allowed_begin();
3119         zonelist = node_zonelist(mempolicy_slab_node(), flags);
3120 
3121 retry:
3122         /*
3123          * Look through allowed nodes for objects available
3124          * from existing per node queues.
3125          */
3126         for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
3127                 nid = zone_to_nid(zone);
3128 
3129                 if (cpuset_zone_allowed(zone, flags) &&
3130                         get_node(cache, nid) &&
3131                         get_node(cache, nid)->free_objects) {
3132                                 obj = ____cache_alloc_node(cache,
3133                                         gfp_exact_node(flags), nid);
3134                                 if (obj)
3135                                         break;
3136                 }
3137         }
3138 
3139         if (!obj) {
3140                 /*
3141                  * This allocation will be performed within the constraints
3142                  * of the current cpuset / memory policy requirements.
3143                  * We may trigger various forms of reclaim on the allowed
3144                  * set and go into memory reserves if necessary.
3145                  */
3146                 page = cache_grow_begin(cache, flags, numa_mem_id());
3147                 cache_grow_end(cache, page);
3148                 if (page) {
3149                         nid = page_to_nid(page);
3150                         obj = ____cache_alloc_node(cache,
3151                                 gfp_exact_node(flags), nid);
3152 
3153                         /*
3154                          * Another processor may allocate the objects in
3155                          * the slab since we are not holding any locks.
3156                          */
3157                         if (!obj)
3158                                 goto retry;
3159                 }
3160         }
3161 
3162         if (unlikely(!obj && read_mems_allowed_retry(cpuset_mems_cookie)))
3163                 goto retry_cpuset;
3164         return obj;
3165 }
3166 
3167 /*
3168  * A interface to enable slab creation on nodeid
3169  */
3170 static void *____cache_alloc_node(struct kmem_cache *cachep, gfp_t flags,
3171                                 int nodeid)
3172 {
3173         struct page *page;
3174         struct kmem_cache_node *n;
3175         void *obj = NULL;
3176         void *list = NULL;
3177 
3178         VM_BUG_ON(nodeid < 0 || nodeid >= MAX_NUMNODES);
3179         n = get_node(cachep, nodeid);
3180         BUG_ON(!n);
3181 
3182         check_irq_off();
3183         spin_lock(&n->list_lock);
3184         page = get_first_slab(n, false);
3185         if (!page)
3186                 goto must_grow;
3187 
3188         check_spinlock_acquired_node(cachep, nodeid);
3189 
3190         STATS_INC_NODEALLOCS(cachep);
3191         STATS_INC_ACTIVE(cachep);
3192         STATS_SET_HIGH(cachep);
3193 
3194         BUG_ON(page->active == cachep->num);
3195 
3196         obj = slab_get_obj(cachep, page);
3197         n->free_objects--;
3198 
3199         fixup_slab_list(cachep, n, page, &list);
3200 
3201         spin_unlock(&n->list_lock);
3202         fixup_objfreelist_debug(cachep, &list);
3203         return obj;
3204 
3205 must_grow:
3206         spin_unlock(&n->list_lock);
3207         page = cache_grow_begin(cachep, gfp_exact_node(flags), nodeid);
3208         if (page) {
3209                 /* This slab isn't counted yet so don't update free_objects */
3210                 obj = slab_get_obj(cachep, page);
3211         }
3212         cache_grow_end(cachep, page);
3213 
3214         return obj ? obj : fallback_alloc(cachep, flags);
3215 }
3216 
3217 static __always_inline void *
3218 slab_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid,
3219                    unsigned long caller)
3220 {
3221         unsigned long save_flags;
3222         void *ptr;
3223         int slab_node = numa_mem_id();
3224 
3225         flags &= gfp_allowed_mask;
3226         cachep = slab_pre_alloc_hook(cachep, flags);
3227         if (unlikely(!cachep))
3228                 return NULL;
3229 
3230         cache_alloc_debugcheck_before(cachep, flags);
3231         local_irq_save(save_flags);
3232 
3233         if (nodeid == NUMA_NO_NODE)
3234                 nodeid = slab_node;
3235 
3236         if (unlikely(!get_node(cachep, nodeid))) {
3237                 /* Node not bootstrapped yet */
3238                 ptr = fallback_alloc(cachep, flags);
3239                 goto out;
3240         }
3241 
3242         if (nodeid == slab_node) {
3243                 /*
3244                  * Use the locally cached objects if possible.
3245                  * However ____cache_alloc does not allow fallback
3246                  * to other nodes. It may fail while we still have
3247                  * objects on other nodes available.
3248                  */
3249                 ptr = ____cache_alloc(cachep, flags);
3250                 if (ptr)
3251                         goto out;
3252         }
3253         /* ___cache_alloc_node can fall back to other nodes */
3254         ptr = ____cache_alloc_node(cachep, flags, nodeid);
3255   out:
3256         local_irq_restore(save_flags);
3257         ptr = cache_alloc_debugcheck_after(cachep, flags, ptr, caller);
3258 
3259         if (unlikely(slab_want_init_on_alloc(flags, cachep)) && ptr)
3260                 memset(ptr, 0, cachep->object_size);
3261 
3262         slab_post_alloc_hook(cachep, flags, 1, &ptr);
3263         return ptr;
3264 }
3265 
3266 static __always_inline void *
3267 __do_cache_alloc(struct kmem_cache *cache, gfp_t flags)
3268 {
3269         void *objp;
3270 
3271         if (current->mempolicy || cpuset_do_slab_mem_spread()) {
3272                 objp = alternate_node_alloc(cache, flags);
3273                 if (objp)
3274                         goto out;
3275         }
3276         objp = ____cache_alloc(cache, flags);
3277 
3278         /*
3279          * We may just have run out of memory on the local node.
3280          * ____cache_alloc_node() knows how to locate memory on other nodes
3281          */
3282         if (!objp)
3283                 objp = ____cache_alloc_node(cache, flags, numa_mem_id());
3284 
3285   out:
3286         return objp;
3287 }
3288 #else
3289 
3290 static __always_inline void *
3291 __do_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
3292 {
3293         return ____cache_alloc(cachep, flags);
3294 }
3295 
3296 #endif /* CONFIG_NUMA */
3297 
3298 static __always_inline void *
3299 slab_alloc(struct kmem_cache *cachep, gfp_t flags, unsigned long caller)
3300 {
3301         unsigned long save_flags;
3302         void *objp;
3303 
3304         flags &= gfp_allowed_mask;
3305         cachep = slab_pre_alloc_hook(cachep, flags);
3306         if (unlikely(!cachep))
3307                 return NULL;
3308 
3309         cache_alloc_debugcheck_before(cachep, flags);
3310         local_irq_save(save_flags);
3311         objp = __do_cache_alloc(cachep, flags);
3312         local_irq_restore(save_flags);
3313         objp = cache_alloc_debugcheck_after(cachep, flags, objp, caller);
3314         prefetchw(objp);
3315 
3316         if (unlikely(slab_want_init_on_alloc(flags, cachep)) && objp)
3317                 memset(objp, 0, cachep->object_size);
3318 
3319         slab_post_alloc_hook(cachep, flags, 1, &objp);
3320         return objp;
3321 }
3322 
3323 /*
3324  * Caller needs to acquire correct kmem_cache_node's list_lock
3325  * @list: List of detached free slabs should be freed by caller
3326  */
3327 static void free_block(struct kmem_cache *cachep, void **objpp,
3328                         int nr_objects, int node, struct list_head *list)
3329 {
3330         int i;
3331         struct kmem_cache_node *n = get_node(cachep, node);
3332         struct page *page;
3333 
3334         n->free_objects += nr_objects;
3335 
3336         for (i = 0; i < nr_objects; i++) {
3337                 void *objp;
3338                 struct page *page;
3339 
3340                 objp = objpp[i];
3341 
3342                 page = virt_to_head_page(objp);
3343                 list_del(&page->slab_list);
3344                 check_spinlock_acquired_node(cachep, node);
3345                 slab_put_obj(cachep, page, objp);
3346                 STATS_DEC_ACTIVE(cachep);
3347 
3348                 /* fixup slab chains */
3349                 if (page->active == 0) {
3350                         list_add(&page->slab_list, &n->slabs_free);
3351                         n->free_slabs++;
3352                 } else {
3353                         /* Unconditionally move a slab to the end of the
3354                          * partial list on free - maximum time for the
3355                          * other objects to be freed, too.
3356                          */
3357                         list_add_tail(&page->slab_list, &n->slabs_partial);
3358                 }
3359         }
3360 
3361         while (n->free_objects > n->free_limit && !list_empty(&n->slabs_free)) {
3362                 n->free_objects -= cachep->num;
3363 
3364                 page = list_last_entry(&n->slabs_free, struct page, slab_list);
3365                 list_move(&page->slab_list, list);
3366                 n->free_slabs--;
3367                 n->total_slabs--;
3368         }
3369 }
3370 
3371 static void cache_flusharray(struct kmem_cache *cachep, struct array_cache *ac)
3372 {
3373         int batchcount;
3374         struct kmem_cache_node *n;
3375         int node = numa_mem_id();
3376         LIST_HEAD(list);
3377 
3378         batchcount = ac->batchcount;
3379 
3380         check_irq_off();
3381         n = get_node(cachep, node);
3382         spin_lock(&n->list_lock);
3383         if (n->shared) {
3384                 struct array_cache *shared_array = n->shared;
3385                 int max = shared_array->limit - shared_array->avail;
3386                 if (max) {
3387                         if (batchcount > max)
3388                                 batchcount = max;
3389                         memcpy(&(shared_array->entry[shared_array->avail]),
3390                                ac->entry, sizeof(void *) * batchcount);
3391                         shared_array->avail += batchcount;
3392                         goto free_done;
3393                 }
3394         }
3395 
3396         free_block(cachep, ac->entry, batchcount, node, &list);
3397 free_done:
3398 #if STATS
3399         {
3400                 int i = 0;
3401                 struct page *page;
3402 
3403                 list_for_each_entry(page, &n->slabs_free, slab_list) {
3404                         BUG_ON(page->active);
3405 
3406                         i++;
3407                 }
3408                 STATS_SET_FREEABLE(cachep, i);
3409         }
3410 #endif
3411         spin_unlock(&n->list_lock);
3412         slabs_destroy(cachep, &list);
3413         ac->avail -= batchcount;
3414         memmove(ac->entry, &(ac->entry[batchcount]), sizeof(void *)*ac->avail);
3415 }
3416 
3417 /*
3418  * Release an obj back to its cache. If the obj has a constructed state, it must
3419  * be in this state _before_ it is released.  Called with disabled ints.
3420  */
3421 static __always_inline void __cache_free(struct kmem_cache *cachep, void *objp,
3422                                          unsigned long caller)
3423 {
3424         /* Put the object into the quarantine, don't touch it for now. */
3425         if (kasan_slab_free(cachep, objp, _RET_IP_))
3426                 return;
3427 
3428         ___cache_free(cachep, objp, caller);
3429 }
3430 
3431 void ___cache_free(struct kmem_cache *cachep, void *objp,
3432                 unsigned long caller)
3433 {
3434         struct array_cache *ac = cpu_cache_get(cachep);
3435 
3436         check_irq_off();
3437         if (unlikely(slab_want_init_on_free(cachep)))
3438                 memset(objp, 0, cachep->object_size);
3439         kmemleak_free_recursive(objp, cachep->flags);
3440         objp = cache_free_debugcheck(cachep, objp, caller);
3441 
3442         /*
3443          * Skip calling cache_free_alien() when the platform is not numa.
3444          * This will avoid cache misses that happen while accessing slabp (which
3445          * is per page memory  reference) to get nodeid. Instead use a global
3446          * variable to skip the call, which is mostly likely to be present in
3447          * the cache.
3448          */
3449         if (nr_online_nodes > 1 && cache_free_alien(cachep, objp))
3450                 return;
3451 
3452         if (ac->avail < ac->limit) {
3453                 STATS_INC_FREEHIT(cachep);
3454         } else {
3455                 STATS_INC_FREEMISS(cachep);
3456                 cache_flusharray(cachep, ac);
3457         }
3458 
3459         if (sk_memalloc_socks()) {
3460                 struct page *page = virt_to_head_page(objp);
3461 
3462                 if (unlikely(PageSlabPfmemalloc(page))) {
3463                         cache_free_pfmemalloc(cachep, page, objp);
3464                         return;
3465                 }
3466         }
3467 
3468         ac->entry[ac->avail++] = objp;
3469 }
3470 
3471 /**
3472  * kmem_cache_alloc - Allocate an object
3473  * @cachep: The cache to allocate from.
3474  * @flags: See kmalloc().
3475  *
3476  * Allocate an object from this cache.  The flags are only relevant
3477  * if the cache has no available objects.
3478  *
3479  * Return: pointer to the new object or %NULL in case of error
3480  */
3481 void *kmem_cache_alloc(struct kmem_cache *cachep, gfp_t flags)
3482 {
3483         void *ret = slab_alloc(cachep, flags, _RET_IP_);
3484 
3485         trace_kmem_cache_alloc(_RET_IP_, ret,
3486                                cachep->object_size, cachep->size, flags);
3487 
3488         return ret;
3489 }
3490 EXPORT_SYMBOL(kmem_cache_alloc);
3491 
3492 static __always_inline void
3493 cache_alloc_debugcheck_after_bulk(struct kmem_cache *s, gfp_t flags,
3494                                   size_t size, void **p, unsigned long caller)
3495 {
3496         size_t i;
3497 
3498         for (i = 0; i < size; i++)
3499                 p[i] = cache_alloc_debugcheck_after(s, flags, p[i], caller);
3500 }
3501 
3502 int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
3503                           void **p)
3504 {
3505         size_t i;
3506 
3507         s = slab_pre_alloc_hook(s, flags);
3508         if (!s)
3509                 return 0;
3510 
3511         cache_alloc_debugcheck_before(s, flags);
3512 
3513         local_irq_disable();
3514         for (i = 0; i < size; i++) {
3515                 void *objp = __do_cache_alloc(s, flags);
3516 
3517                 if (unlikely(!objp))
3518                         goto error;
3519                 p[i] = objp;
3520         }
3521         local_irq_enable();
3522 
3523         cache_alloc_debugcheck_after_bulk(s, flags, size, p, _RET_IP_);
3524 
3525         /* Clear memory outside IRQ disabled section */
3526         if (unlikely(slab_want_init_on_alloc(flags, s)))
3527                 for (i = 0; i < size; i++)
3528                         memset(p[i], 0, s->object_size);
3529 
3530         slab_post_alloc_hook(s, flags, size, p);
3531         /* FIXME: Trace call missing. Christoph would like a bulk variant */
3532         return size;
3533 error:
3534         local_irq_enable();
3535         cache_alloc_debugcheck_after_bulk(s, flags, i, p, _RET_IP_);
3536         slab_post_alloc_hook(s, flags, i, p);
3537         __kmem_cache_free_bulk(s, i, p);
3538         return 0;
3539 }
3540 EXPORT_SYMBOL(kmem_cache_alloc_bulk);
3541 
3542 #ifdef CONFIG_TRACING
3543 void *
3544 kmem_cache_alloc_trace(struct kmem_cache *cachep, gfp_t flags, size_t size)
3545 {
3546         void *ret;
3547 
3548         ret = slab_alloc(cachep, flags, _RET_IP_);
3549 
3550         ret = kasan_kmalloc(cachep, ret, size, flags);
3551         trace_kmalloc(_RET_IP_, ret,
3552                       size, cachep->size, flags);
3553         return ret;
3554 }
3555 EXPORT_SYMBOL(kmem_cache_alloc_trace);
3556 #endif
3557 
3558 #ifdef CONFIG_NUMA
3559 /**
3560  * kmem_cache_alloc_node - Allocate an object on the specified node
3561  * @cachep: The cache to allocate from.
3562  * @flags: See kmalloc().
3563  * @nodeid: node number of the target node.
3564  *
3565  * Identical to kmem_cache_alloc but it will allocate memory on the given
3566  * node, which can improve the performance for cpu bound structures.
3567  *
3568  * Fallback to other node is possible if __GFP_THISNODE is not set.
3569  *
3570  * Return: pointer to the new object or %NULL in case of error
3571  */
3572 void *kmem_cache_alloc_node(struct kmem_cache *cachep, gfp_t flags, int nodeid)
3573 {
3574         void *ret = slab_alloc_node(cachep, flags, nodeid, _RET_IP_);
3575 
3576         trace_kmem_cache_alloc_node(_RET_IP_, ret,
3577                                     cachep->object_size, cachep->size,
3578                                     flags, nodeid);
3579 
3580         return ret;
3581 }
3582 EXPORT_SYMBOL(kmem_cache_alloc_node);
3583 
3584 #ifdef CONFIG_TRACING
3585 void *kmem_cache_alloc_node_trace(struct kmem_cache *cachep,
3586                                   gfp_t flags,
3587                                   int nodeid,
3588                                   size_t size)
3589 {
3590         void *ret;
3591 
3592         ret = slab_alloc_node(cachep, flags, nodeid, _RET_IP_);
3593 
3594         ret = kasan_kmalloc(cachep, ret, size, flags);
3595         trace_kmalloc_node(_RET_IP_, ret,
3596                            size, cachep->size,
3597                            flags, nodeid);
3598         return ret;
3599 }
3600 EXPORT_SYMBOL(kmem_cache_alloc_node_trace);
3601 #endif
3602 
3603 static __always_inline void *
3604 __do_kmalloc_node(size_t size, gfp_t flags, int node, unsigned long caller)
3605 {
3606         struct kmem_cache *cachep;
3607         void *ret;
3608 
3609         if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
3610                 return NULL;
3611         cachep = kmalloc_slab(size, flags);
3612         if (unlikely(ZERO_OR_NULL_PTR(cachep)))
3613                 return cachep;
3614         ret = kmem_cache_alloc_node_trace(cachep, flags, node, size);
3615         ret = kasan_kmalloc(cachep, ret, size, flags);
3616 
3617         return ret;
3618 }
3619 
3620 void *__kmalloc_node(size_t size, gfp_t flags, int node)
3621 {
3622         return __do_kmalloc_node(size, flags, node, _RET_IP_);
3623 }
3624 EXPORT_SYMBOL(__kmalloc_node);
3625 
3626 void *__kmalloc_node_track_caller(size_t size, gfp_t flags,
3627                 int node, unsigned long caller)
3628 {
3629         return __do_kmalloc_node(size, flags, node, caller);
3630 }
3631 EXPORT_SYMBOL(__kmalloc_node_track_caller);
3632 #endif /* CONFIG_NUMA */
3633 
3634 /**
3635  * __do_kmalloc - allocate memory
3636  * @size: how many bytes of memory are required.
3637  * @flags: the type of memory to allocate (see kmalloc).
3638  * @caller: function caller for debug tracking of the caller
3639  *
3640  * Return: pointer to the allocated memory or %NULL in case of error
3641  */
3642 static __always_inline void *__do_kmalloc(size_t size, gfp_t flags,
3643                                           unsigned long caller)
3644 {
3645         struct kmem_cache *cachep;
3646         void *ret;
3647 
3648         if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
3649                 return NULL;
3650         cachep = kmalloc_slab(size, flags);
3651         if (unlikely(ZERO_OR_NULL_PTR(cachep)))
3652                 return cachep;
3653         ret = slab_alloc(cachep, flags, caller);
3654 
3655         ret = kasan_kmalloc(cachep, ret, size, flags);
3656         trace_kmalloc(caller, ret,
3657                       size, cachep->size, flags);
3658 
3659         return ret;
3660 }
3661 
3662 void *__kmalloc(size_t size, gfp_t flags)
3663 {
3664         return __do_kmalloc(size, flags, _RET_IP_);
3665 }
3666 EXPORT_SYMBOL(__kmalloc);
3667 
3668 void *__kmalloc_track_caller(size_t size, gfp_t flags, unsigned long caller)
3669 {
3670         return __do_kmalloc(size, flags, caller);
3671 }
3672 EXPORT_SYMBOL(__kmalloc_track_caller);
3673 
3674 /**
3675  * kmem_cache_free - Deallocate an object
3676  * @cachep: The cache the allocation was from.
3677  * @objp: The previously allocated object.
3678  *
3679  * Free an object which was previously allocated from this
3680  * cache.
3681  */
3682 void kmem_cache_free(struct kmem_cache *cachep, void *objp)
3683 {
3684         unsigned long flags;
3685         cachep = cache_from_obj(cachep, objp);
3686         if (!cachep)
3687                 return;
3688 
3689         local_irq_save(flags);
3690         debug_check_no_locks_freed(objp, cachep->object_size);
3691         if (!(cachep->flags & SLAB_DEBUG_OBJECTS))
3692                 debug_check_no_obj_freed(objp, cachep->object_size);
3693         __cache_free(cachep, objp, _RET_IP_);
3694         local_irq_restore(flags);
3695 
3696         trace_kmem_cache_free(_RET_IP_, objp);
3697 }
3698 EXPORT_SYMBOL(kmem_cache_free);
3699 
3700 void kmem_cache_free_bulk(struct kmem_cache *orig_s, size_t size, void **p)
3701 {
3702         struct kmem_cache *s;
3703         size_t i;
3704 
3705         local_irq_disable();
3706         for (i = 0; i < size; i++) {
3707                 void *objp = p[i];
3708 
3709                 if (!orig_s) /* called via kfree_bulk */
3710                         s = virt_to_cache(objp);
3711                 else
3712                         s = cache_from_obj(orig_s, objp);
3713                 if (!s)
3714                         continue;
3715 
3716                 debug_check_no_locks_freed(objp, s->object_size);
3717                 if (!(s->flags & SLAB_DEBUG_OBJECTS))
3718                         debug_check_no_obj_freed(objp, s->object_size);
3719 
3720                 __cache_free(s, objp, _RET_IP_);
3721         }
3722         local_irq_enable();
3723 
3724         /* FIXME: add tracing */
3725 }
3726 EXPORT_SYMBOL(kmem_cache_free_bulk);
3727 
3728 /**
3729  * kfree - free previously allocated memory
3730  * @objp: pointer returned by kmalloc.
3731  *
3732  * If @objp is NULL, no operation is performed.
3733  *
3734  * Don't free memory not originally allocated by kmalloc()
3735  * or you will run into trouble.
3736  */
3737 void kfree(const void *objp)
3738 {
3739         struct kmem_cache *c;
3740         unsigned long flags;
3741 
3742         trace_kfree(_RET_IP_, objp);
3743 
3744         if (unlikely(ZERO_OR_NULL_PTR(objp)))
3745                 return;
3746         local_irq_save(flags);
3747         kfree_debugcheck(objp);
3748         c = virt_to_cache(objp);
3749         if (!c) {
3750                 local_irq_restore(flags);
3751                 return;
3752         }
3753         debug_check_no_locks_freed(objp, c->object_size);
3754 
3755         debug_check_no_obj_freed(objp, c->object_size);
3756         __cache_free(c, (void *)objp, _RET_IP_);
3757         local_irq_restore(flags);
3758 }
3759 EXPORT_SYMBOL(kfree);
3760 
3761 /*
3762  * This initializes kmem_cache_node or resizes various caches for all nodes.
3763  */
3764 static int setup_kmem_cache_nodes(struct kmem_cache *cachep, gfp_t gfp)
3765 {
3766         int ret;
3767         int node;
3768         struct kmem_cache_node *n;
3769 
3770         for_each_online_node(node) {
3771                 ret = setup_kmem_cache_node(cachep, node, gfp, true);
3772                 if (ret)
3773                         goto fail;
3774 
3775         }
3776 
3777         return 0;
3778 
3779 fail:
3780         if (!cachep->list.next) {
3781                 /* Cache is not active yet. Roll back what we did */
3782                 node--;
3783                 while (node >= 0) {
3784                         n = get_node(cachep, node);
3785                         if (n) {
3786                                 kfree(n->shared);
3787                                 free_alien_cache(n->alien);
3788                                 kfree(n);
3789                                 cachep->node[node] = NULL;
3790                         }
3791                         node--;
3792                 }
3793         }
3794         return -ENOMEM;
3795 }
3796 
3797 /* Always called with the slab_mutex held */
3798 static int __do_tune_cpucache(struct kmem_cache *cachep, int limit,
3799                                 int batchcount, int shared, gfp_t gfp)
3800 {
3801         struct array_cache __percpu *cpu_cache, *prev;
3802         int cpu;
3803 
3804         cpu_cache = alloc_kmem_cache_cpus(cachep, limit, batchcount);
3805         if (!cpu_cache)
3806                 return -ENOMEM;
3807 
3808         prev = cachep->cpu_cache;
3809         cachep->cpu_cache = cpu_cache;
3810         /*
3811          * Without a previous cpu_cache there's no need to synchronize remote
3812          * cpus, so skip the IPIs.
3813          */
3814         if (prev)
3815                 kick_all_cpus_sync();
3816 
3817         check_irq_on();
3818         cachep->batchcount = batchcount;
3819         cachep->limit = limit;
3820         cachep->shared = shared;
3821 
3822         if (!prev)
3823                 goto setup_node;
3824 
3825         for_each_online_cpu(cpu) {
3826                 LIST_HEAD(list);
3827                 int node;
3828                 struct kmem_cache_node *n;
3829                 struct array_cache *ac = per_cpu_ptr(prev, cpu);
3830 
3831                 node = cpu_to_mem(cpu);
3832                 n = get_node(cachep, node);
3833                 spin_lock_irq(&n->list_lock);
3834                 free_block(cachep, ac->entry, ac->avail, node, &list);
3835                 spin_unlock_irq(&n->list_lock);
3836                 slabs_destroy(cachep, &list);
3837         }
3838         free_percpu(prev);
3839 
3840 setup_node:
3841         return setup_kmem_cache_nodes(cachep, gfp);
3842 }
3843 
3844 static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
3845                                 int batchcount, int shared, gfp_t gfp)
3846 {
3847         int ret;
3848         struct kmem_cache *c;
3849 
3850         ret = __do_tune_cpucache(cachep, limit, batchcount, shared, gfp);
3851 
3852         if (slab_state < FULL)
3853                 return ret;
3854 
3855         if ((ret < 0) || !is_root_cache(cachep))
3856                 return ret;
3857 
3858         lockdep_assert_held(&slab_mutex);
3859         for_each_memcg_cache(c, cachep) {
3860                 /* return value determined by the root cache only */
3861                 __do_tune_cpucache(c, limit, batchcount, shared, gfp);
3862         }
3863 
3864         return ret;
3865 }
3866 
3867 /* Called with slab_mutex held always */
3868 static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp)
3869 {
3870         int err;
3871         int limit = 0;
3872         int shared = 0;
3873         int batchcount = 0;
3874 
3875         err = cache_random_seq_create(cachep, cachep->num, gfp);
3876         if (err)
3877                 goto end;
3878 
3879         if (!is_root_cache(cachep)) {
3880                 struct kmem_cache *root = memcg_root_cache(cachep);
3881                 limit = root->limit;
3882                 shared = root->shared;
3883                 batchcount = root->batchcount;
3884         }
3885 
3886         if (limit && shared && batchcount)
3887                 goto skip_setup;
3888         /*
3889          * The head array serves three purposes:
3890          * - create a LIFO ordering, i.e. return objects that are cache-warm
3891          * - reduce the number of spinlock operations.
3892          * - reduce the number of linked list operations on the slab and
3893          *   bufctl chains: array operations are cheaper.
3894          * The numbers are guessed, we should auto-tune as described by
3895          * Bonwick.
3896          */
3897         if (cachep->size > 131072)
3898                 limit = 1;
3899         else if (cachep->size > PAGE_SIZE)
3900                 limit = 8;
3901         else if (cachep->size > 1024)
3902                 limit = 24;
3903         else if (cachep->size > 256)
3904                 limit = 54;
3905         else
3906                 limit = 120;
3907 
3908         /*
3909          * CPU bound tasks (e.g. network routing) can exhibit cpu bound
3910          * allocation behaviour: Most allocs on one cpu, most free operations
3911          * on another cpu. For these cases, an efficient object passing between
3912          * cpus is necessary. This is provided by a shared array. The array
3913          * replaces Bonwick's magazine layer.
3914          * On uniprocessor, it's functionally equivalent (but less efficient)
3915          * to a larger limit. Thus disabled by default.
3916          */
3917         shared = 0;
3918         if (cachep->size <= PAGE_SIZE && num_possible_cpus() > 1)
3919                 shared = 8;
3920 
3921 #if DEBUG
3922         /*
3923          * With debugging enabled, large batchcount lead to excessively long
3924          * periods with disabled local interrupts. Limit the batchcount
3925          */
3926         if (limit > 32)
3927                 limit = 32;
3928 #endif
3929         batchcount = (limit + 1) / 2;
3930 skip_setup:
3931         err = do_tune_cpucache(cachep, limit, batchcount, shared, gfp);
3932 end:
3933         if (err)
3934                 pr_err("enable_cpucache failed for %s, error %d\n",
3935                        cachep->name, -err);
3936         return err;
3937 }
3938 
3939 /*
3940  * Drain an array if it contains any elements taking the node lock only if
3941  * necessary. Note that the node listlock also protects the array_cache
3942  * if drain_array() is used on the shared array.
3943  */
3944 static void drain_array(struct kmem_cache *cachep, struct kmem_cache_node *n,
3945                          struct array_cache *ac, int node)
3946 {
3947         LIST_HEAD(list);
3948 
3949         /* ac from n->shared can be freed if we don't hold the slab_mutex. */
3950         check_mutex_acquired();
3951 
3952         if (!ac || !ac->avail)
3953                 return;
3954 
3955         if (ac->touched) {
3956                 ac->touched = 0;
3957                 return;
3958         }
3959 
3960         spin_lock_irq(&n->list_lock);
3961         drain_array_locked(cachep, ac, node, false, &list);
3962         spin_unlock_irq(&n->list_lock);
3963 
3964         slabs_destroy(cachep, &list);
3965 }
3966 
3967 /**
3968  * cache_reap - Reclaim memory from caches.
3969  * @w: work descriptor
3970  *
3971  * Called from workqueue/eventd every few seconds.
3972  * Purpose:
3973  * - clear the per-cpu caches for this CPU.
3974  * - return freeable pages to the main free memory pool.
3975  *
3976  * If we cannot acquire the cache chain mutex then just give up - we'll try
3977  * again on the next iteration.
3978  */
3979 static void cache_reap(struct work_struct *w)
3980 {
3981         struct kmem_cache *searchp;
3982         struct kmem_cache_node *n;
3983         int node = numa_mem_id();
3984         struct delayed_work *work = to_delayed_work(w);
3985 
3986         if (!mutex_trylock(&slab_mutex))
3987                 /* Give up. Setup the next iteration. */
3988                 goto out;
3989 
3990         list_for_each_entry(searchp, &slab_caches, list) {
3991                 check_irq_on();
3992 
3993                 /*
3994                  * We only take the node lock if absolutely necessary and we
3995                  * have established with reasonable certainty that
3996                  * we can do some work if the lock was obtained.
3997                  */
3998                 n = get_node(searchp, node);
3999 
4000                 reap_alien(searchp, n);
4001 
4002                 drain_array(searchp, n, cpu_cache_get(searchp), node);
4003 
4004                 /*
4005                  * These are racy checks but it does not matter
4006                  * if we skip one check or scan twice.
4007                  */
4008                 if (time_after(n->next_reap, jiffies))
4009                         goto next;
4010 
4011                 n->next_reap = jiffies + REAPTIMEOUT_NODE;
4012 
4013                 drain_array(searchp, n, n->shared, node);
4014 
4015                 if (n->free_touched)
4016                         n->free_touched = 0;
4017                 else {
4018                         int freed;
4019 
4020                         freed = drain_freelist(searchp, n, (n->free_limit +
4021                                 5 * searchp->num - 1) / (5 * searchp->num));
4022                         STATS_ADD_REAPED(searchp, freed);
4023                 }
4024 next:
4025                 cond_resched();
4026         }
4027         check_irq_on();
4028         mutex_unlock(&slab_mutex);
4029         next_reap_node();
4030 out:
4031         /* Set up the next iteration */
4032         schedule_delayed_work_on(smp_processor_id(), work,
4033                                 round_jiffies_relative(REAPTIMEOUT_AC));
4034 }
4035 
4036 void get_slabinfo(struct kmem_cache *cachep, struct slabinfo *sinfo)
4037 {
4038         unsigned long active_objs, num_objs, active_slabs;
4039         unsigned long total_slabs = 0, free_objs = 0, shared_avail = 0;
4040         unsigned long free_slabs = 0;
4041         int node;
4042         struct kmem_cache_node *n;
4043 
4044         for_each_kmem_cache_node(cachep, node, n) {
4045                 check_irq_on();
4046                 spin_lock_irq(&n->list_lock);
4047 
4048                 total_slabs += n->total_slabs;
4049                 free_slabs += n->free_slabs;
4050                 free_objs += n->free_objects;
4051 
4052                 if (n->shared)
4053                         shared_avail += n->shared->avail;
4054 
4055                 spin_unlock_irq(&n->list_lock);
4056         }
4057         num_objs = total_slabs * cachep->num;
4058         active_slabs = total_slabs - free_slabs;
4059         active_objs = num_objs - free_objs;
4060 
4061         sinfo->active_objs = active_objs;
4062         sinfo->num_objs = num_objs;
4063         sinfo->active_slabs = active_slabs;
4064         sinfo->num_slabs = total_slabs;
4065         sinfo->shared_avail = shared_avail;
4066         sinfo->limit = cachep->limit;
4067         sinfo->batchcount = cachep->batchcount;
4068         sinfo->shared = cachep->shared;
4069         sinfo->objects_per_slab = cachep->num;
4070         sinfo->cache_order = cachep->gfporder;
4071 }
4072 
4073 void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *cachep)
4074 {
4075 #if STATS
4076         {                       /* node stats */
4077                 unsigned long high = cachep->high_mark;
4078                 unsigned long allocs = cachep->num_allocations;
4079                 unsigned long grown = cachep->grown;
4080                 unsigned long reaped = cachep->reaped;
4081                 unsigned long errors = cachep->errors;
4082                 unsigned long max_freeable = cachep->max_freeable;
4083                 unsigned long node_allocs = cachep->node_allocs;
4084                 unsigned long node_frees = cachep->node_frees;
4085                 unsigned long overflows = cachep->node_overflow;
4086 
4087                 seq_printf(m, " : globalstat %7lu %6lu %5lu %4lu %4lu %4lu %4lu %4lu %4lu",
4088                            allocs, high, grown,
4089                            reaped, errors, max_freeable, node_allocs,
4090                            node_frees, overflows);
4091         }
4092         /* cpu stats */
4093         {
4094                 unsigned long allochit = atomic_read(&cachep->allochit);
4095                 unsigned long allocmiss = atomic_read(&cachep->allocmiss);
4096                 unsigned long freehit = atomic_read(&cachep->freehit);
4097                 unsigned long freemiss = atomic_read(&cachep->freemiss);
4098 
4099                 seq_printf(m, " : cpustat %6lu %6lu %6lu %6lu",
4100                            allochit, allocmiss, freehit, freemiss);
4101         }
4102 #endif
4103 }
4104 
4105 #define MAX_SLABINFO_WRITE 128
4106 /**
4107  * slabinfo_write - Tuning for the slab allocator
4108  * @file: unused
4109  * @buffer: user buffer
4110  * @count: data length
4111  * @ppos: unused
4112  *
4113  * Return: %0 on success, negative error code otherwise.
4114  */
4115 ssize_t slabinfo_write(struct file *file, const char __user *buffer,
4116                        size_t count, loff_t *ppos)
4117 {
4118         char kbuf[MAX_SLABINFO_WRITE + 1], *tmp;
4119         int limit, batchcount, shared, res;
4120         struct kmem_cache *cachep;
4121 
4122         if (count > MAX_SLABINFO_WRITE)
4123                 return -EINVAL;
4124         if (copy_from_user(&kbuf, buffer, count))
4125                 return -EFAULT;
4126         kbuf[MAX_SLABINFO_WRITE] = '\0';
4127 
4128         tmp = strchr(kbuf, ' ');
4129         if (!tmp)
4130                 return -EINVAL;
4131         *tmp = '\0';
4132         tmp++;
4133         if (sscanf(tmp, " %d %d %d", &limit, &batchcount, &shared) != 3)
4134                 return -EINVAL;
4135 
4136         /* Find the cache in the chain of caches. */
4137         mutex_lock(&slab_mutex);
4138         res = -EINVAL;
4139         list_for_each_entry(cachep, &slab_caches, list) {
4140                 if (!strcmp(cachep->name, kbuf)) {
4141                         if (limit < 1 || batchcount < 1 ||
4142                                         batchcount > limit || shared < 0) {
4143                                 res = 0;
4144                         } else {
4145                                 res = do_tune_cpucache(cachep, limit,
4146                                                        batchcount, shared,
4147                                                        GFP_KERNEL);
4148                         }
4149                         break;
4150                 }
4151         }
4152         mutex_unlock(&slab_mutex);
4153         if (res >= 0)
4154                 res = count;
4155         return res;
4156 }
4157 
4158 #ifdef CONFIG_HARDENED_USERCOPY
4159 /*
4160  * Rejects incorrectly sized objects and objects that are to be copied
4161  * to/from userspace but do not fall entirely within the containing slab
4162  * cache's usercopy region.
4163  *
4164  * Returns NULL if check passes, otherwise const char * to name of cache
4165  * to indicate an error.
4166  */
4167 void __check_heap_object(const void *ptr, unsigned long n, struct page *page,
4168                          bool to_user)
4169 {
4170         struct kmem_cache *cachep;
4171         unsigned int objnr;
4172         unsigned long offset;
4173 
4174         ptr = kasan_reset_tag(ptr);
4175 
4176         /* Find and validate object. */
4177         cachep = page->slab_cache;
4178         objnr = obj_to_index(cachep, page, (void *)ptr);
4179         BUG_ON(objnr >= cachep->num);
4180 
4181         /* Find offset within object. */
4182         offset = ptr - index_to_obj(cachep, page, objnr) - obj_offset(cachep);
4183 
4184         /* Allow address range falling entirely within usercopy region. */
4185         if (offset >= cachep->useroffset &&
4186             offset - cachep->useroffset <= cachep->usersize &&
4187             n <= cachep->useroffset - offset + cachep->usersize)
4188                 return;
4189 
4190         /*
4191          * If the copy is still within the allocated object, produce
4192          * a warning instead of rejecting the copy. This is intended
4193          * to be a temporary method to find any missing usercopy
4194          * whitelists.
4195          */
4196         if (usercopy_fallback &&
4197             offset <= cachep->object_size &&
4198             n <= cachep->object_size - offset) {
4199                 usercopy_warn("SLAB object", cachep->name, to_user, offset, n);
4200                 return;
4201         }
4202 
4203         usercopy_abort("SLAB object", cachep->name, to_user, offset, n);
4204 }
4205 #endif /* CONFIG_HARDENED_USERCOPY */
4206 
4207 /**
4208  * __ksize -- Uninstrumented ksize.
4209  * @objp: pointer to the object
4210  *
4211  * Unlike ksize(), __ksize() is uninstrumented, and does not provide the same
4212  * safety checks as ksize() with KASAN instrumentation enabled.
4213  *
4214  * Return: size of the actual memory used by @objp in bytes
4215  */
4216 size_t __ksize(const void *objp)
4217 {
4218         struct kmem_cache *c;
4219         size_t size;
4220 
4221         BUG_ON(!objp);
4222         if (unlikely(objp == ZERO_SIZE_PTR))
4223                 return 0;
4224 
4225         c = virt_to_cache(objp);
4226         size = c ? c->object_size : 0;
4227 
4228         return size;
4229 }
4230 EXPORT_SYMBOL(__ksize);
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root/mm/slab.c

DEFINITIONS
