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TOMOYO Linux Cross Reference
Linux/mm/slub.c

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  1 /*
  2  * SLUB: A slab allocator that limits cache line use instead of queuing
  3  * objects in per cpu and per node lists.
  4  *
  5  * The allocator synchronizes using per slab locks or atomic operatios
  6  * and only uses a centralized lock to manage a pool of partial slabs.
  7  *
  8  * (C) 2007 SGI, Christoph Lameter
  9  * (C) 2011 Linux Foundation, Christoph Lameter
 10  */
 11 
 12 #include <linux/mm.h>
 13 #include <linux/swap.h> /* struct reclaim_state */
 14 #include <linux/module.h>
 15 #include <linux/bit_spinlock.h>
 16 #include <linux/interrupt.h>
 17 #include <linux/bitops.h>
 18 #include <linux/slab.h>
 19 #include "slab.h"
 20 #include <linux/proc_fs.h>
 21 #include <linux/notifier.h>
 22 #include <linux/seq_file.h>
 23 #include <linux/kasan.h>
 24 #include <linux/kmemcheck.h>
 25 #include <linux/cpu.h>
 26 #include <linux/cpuset.h>
 27 #include <linux/mempolicy.h>
 28 #include <linux/ctype.h>
 29 #include <linux/debugobjects.h>
 30 #include <linux/kallsyms.h>
 31 #include <linux/memory.h>
 32 #include <linux/math64.h>
 33 #include <linux/fault-inject.h>
 34 #include <linux/stacktrace.h>
 35 #include <linux/prefetch.h>
 36 #include <linux/memcontrol.h>
 37 
 38 #include <trace/events/kmem.h>
 39 
 40 #include "internal.h"
 41 
 42 /*
 43  * Lock order:
 44  *   1. slab_mutex (Global Mutex)
 45  *   2. node->list_lock
 46  *   3. slab_lock(page) (Only on some arches and for debugging)
 47  *
 48  *   slab_mutex
 49  *
 50  *   The role of the slab_mutex is to protect the list of all the slabs
 51  *   and to synchronize major metadata changes to slab cache structures.
 52  *
 53  *   The slab_lock is only used for debugging and on arches that do not
 54  *   have the ability to do a cmpxchg_double. It only protects the second
 55  *   double word in the page struct. Meaning
 56  *      A. page->freelist       -> List of object free in a page
 57  *      B. page->counters       -> Counters of objects
 58  *      C. page->frozen         -> frozen state
 59  *
 60  *   If a slab is frozen then it is exempt from list management. It is not
 61  *   on any list. The processor that froze the slab is the one who can
 62  *   perform list operations on the page. Other processors may put objects
 63  *   onto the freelist but the processor that froze the slab is the only
 64  *   one that can retrieve the objects from the page's freelist.
 65  *
 66  *   The list_lock protects the partial and full list on each node and
 67  *   the partial slab counter. If taken then no new slabs may be added or
 68  *   removed from the lists nor make the number of partial slabs be modified.
 69  *   (Note that the total number of slabs is an atomic value that may be
 70  *   modified without taking the list lock).
 71  *
 72  *   The list_lock is a centralized lock and thus we avoid taking it as
 73  *   much as possible. As long as SLUB does not have to handle partial
 74  *   slabs, operations can continue without any centralized lock. F.e.
 75  *   allocating a long series of objects that fill up slabs does not require
 76  *   the list lock.
 77  *   Interrupts are disabled during allocation and deallocation in order to
 78  *   make the slab allocator safe to use in the context of an irq. In addition
 79  *   interrupts are disabled to ensure that the processor does not change
 80  *   while handling per_cpu slabs, due to kernel preemption.
 81  *
 82  * SLUB assigns one slab for allocation to each processor.
 83  * Allocations only occur from these slabs called cpu slabs.
 84  *
 85  * Slabs with free elements are kept on a partial list and during regular
 86  * operations no list for full slabs is used. If an object in a full slab is
 87  * freed then the slab will show up again on the partial lists.
 88  * We track full slabs for debugging purposes though because otherwise we
 89  * cannot scan all objects.
 90  *
 91  * Slabs are freed when they become empty. Teardown and setup is
 92  * minimal so we rely on the page allocators per cpu caches for
 93  * fast frees and allocs.
 94  *
 95  * Overloading of page flags that are otherwise used for LRU management.
 96  *
 97  * PageActive           The slab is frozen and exempt from list processing.
 98  *                      This means that the slab is dedicated to a purpose
 99  *                      such as satisfying allocations for a specific
100  *                      processor. Objects may be freed in the slab while
101  *                      it is frozen but slab_free will then skip the usual
102  *                      list operations. It is up to the processor holding
103  *                      the slab to integrate the slab into the slab lists
104  *                      when the slab is no longer needed.
105  *
106  *                      One use of this flag is to mark slabs that are
107  *                      used for allocations. Then such a slab becomes a cpu
108  *                      slab. The cpu slab may be equipped with an additional
109  *                      freelist that allows lockless access to
110  *                      free objects in addition to the regular freelist
111  *                      that requires the slab lock.
112  *
113  * PageError            Slab requires special handling due to debug
114  *                      options set. This moves slab handling out of
115  *                      the fast path and disables lockless freelists.
116  */
117 
118 static inline int kmem_cache_debug(struct kmem_cache *s)
119 {
120 #ifdef CONFIG_SLUB_DEBUG
121         return unlikely(s->flags & SLAB_DEBUG_FLAGS);
122 #else
123         return 0;
124 #endif
125 }
126 
127 static inline void *fixup_red_left(struct kmem_cache *s, void *p)
128 {
129         if (kmem_cache_debug(s) && s->flags & SLAB_RED_ZONE)
130                 p += s->red_left_pad;
131 
132         return p;
133 }
134 
135 static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s)
136 {
137 #ifdef CONFIG_SLUB_CPU_PARTIAL
138         return !kmem_cache_debug(s);
139 #else
140         return false;
141 #endif
142 }
143 
144 /*
145  * Issues still to be resolved:
146  *
147  * - Support PAGE_ALLOC_DEBUG. Should be easy to do.
148  *
149  * - Variable sizing of the per node arrays
150  */
151 
152 /* Enable to test recovery from slab corruption on boot */
153 #undef SLUB_RESILIENCY_TEST
154 
155 /* Enable to log cmpxchg failures */
156 #undef SLUB_DEBUG_CMPXCHG
157 
158 /*
159  * Mininum number of partial slabs. These will be left on the partial
160  * lists even if they are empty. kmem_cache_shrink may reclaim them.
161  */
162 #define MIN_PARTIAL 5
163 
164 /*
165  * Maximum number of desirable partial slabs.
166  * The existence of more partial slabs makes kmem_cache_shrink
167  * sort the partial list by the number of objects in use.
168  */
169 #define MAX_PARTIAL 10
170 
171 #define DEBUG_DEFAULT_FLAGS (SLAB_CONSISTENCY_CHECKS | SLAB_RED_ZONE | \
172                                 SLAB_POISON | SLAB_STORE_USER)
173 
174 /*
175  * These debug flags cannot use CMPXCHG because there might be consistency
176  * issues when checking or reading debug information
177  */
178 #define SLAB_NO_CMPXCHG (SLAB_CONSISTENCY_CHECKS | SLAB_STORE_USER | \
179                                 SLAB_TRACE)
180 
181 
182 /*
183  * Debugging flags that require metadata to be stored in the slab.  These get
184  * disabled when slub_debug=O is used and a cache's min order increases with
185  * metadata.
186  */
187 #define DEBUG_METADATA_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER)
188 
189 #define OO_SHIFT        16
190 #define OO_MASK         ((1 << OO_SHIFT) - 1)
191 #define MAX_OBJS_PER_PAGE       32767 /* since page.objects is u15 */
192 
193 /* Internal SLUB flags */
194 #define __OBJECT_POISON         0x80000000UL /* Poison object */
195 #define __CMPXCHG_DOUBLE        0x40000000UL /* Use cmpxchg_double */
196 
197 #ifdef CONFIG_SMP
198 static struct notifier_block slab_notifier;
199 #endif
200 
201 /*
202  * Tracking user of a slab.
203  */
204 #define TRACK_ADDRS_COUNT 16
205 struct track {
206         unsigned long addr;     /* Called from address */
207 #ifdef CONFIG_STACKTRACE
208         unsigned long addrs[TRACK_ADDRS_COUNT]; /* Called from address */
209 #endif
210         int cpu;                /* Was running on cpu */
211         int pid;                /* Pid context */
212         unsigned long when;     /* When did the operation occur */
213 };
214 
215 enum track_item { TRACK_ALLOC, TRACK_FREE };
216 
217 #ifdef CONFIG_SYSFS
218 static int sysfs_slab_add(struct kmem_cache *);
219 static int sysfs_slab_alias(struct kmem_cache *, const char *);
220 static void memcg_propagate_slab_attrs(struct kmem_cache *s);
221 #else
222 static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; }
223 static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p)
224                                                         { return 0; }
225 static inline void memcg_propagate_slab_attrs(struct kmem_cache *s) { }
226 #endif
227 
228 static inline void stat(const struct kmem_cache *s, enum stat_item si)
229 {
230 #ifdef CONFIG_SLUB_STATS
231         /*
232          * The rmw is racy on a preemptible kernel but this is acceptable, so
233          * avoid this_cpu_add()'s irq-disable overhead.
234          */
235         raw_cpu_inc(s->cpu_slab->stat[si]);
236 #endif
237 }
238 
239 /********************************************************************
240  *                      Core slab cache functions
241  *******************************************************************/
242 
243 static inline void *get_freepointer(struct kmem_cache *s, void *object)
244 {
245         return *(void **)(object + s->offset);
246 }
247 
248 static void prefetch_freepointer(const struct kmem_cache *s, void *object)
249 {
250         prefetch(object + s->offset);
251 }
252 
253 static inline void *get_freepointer_safe(struct kmem_cache *s, void *object)
254 {
255         void *p;
256 
257         if (!debug_pagealloc_enabled())
258                 return get_freepointer(s, object);
259 
260         probe_kernel_read(&p, (void **)(object + s->offset), sizeof(p));
261         return p;
262 }
263 
264 static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp)
265 {
266         *(void **)(object + s->offset) = fp;
267 }
268 
269 /* Loop over all objects in a slab */
270 #define for_each_object(__p, __s, __addr, __objects) \
271         for (__p = fixup_red_left(__s, __addr); \
272                 __p < (__addr) + (__objects) * (__s)->size; \
273                 __p += (__s)->size)
274 
275 #define for_each_object_idx(__p, __idx, __s, __addr, __objects) \
276         for (__p = fixup_red_left(__s, __addr), __idx = 1; \
277                 __idx <= __objects; \
278                 __p += (__s)->size, __idx++)
279 
280 /* Determine object index from a given position */
281 static inline int slab_index(void *p, struct kmem_cache *s, void *addr)
282 {
283         return (p - addr) / s->size;
284 }
285 
286 static inline int order_objects(int order, unsigned long size, int reserved)
287 {
288         return ((PAGE_SIZE << order) - reserved) / size;
289 }
290 
291 static inline struct kmem_cache_order_objects oo_make(int order,
292                 unsigned long size, int reserved)
293 {
294         struct kmem_cache_order_objects x = {
295                 (order << OO_SHIFT) + order_objects(order, size, reserved)
296         };
297 
298         return x;
299 }
300 
301 static inline int oo_order(struct kmem_cache_order_objects x)
302 {
303         return x.x >> OO_SHIFT;
304 }
305 
306 static inline int oo_objects(struct kmem_cache_order_objects x)
307 {
308         return x.x & OO_MASK;
309 }
310 
311 /*
312  * Per slab locking using the pagelock
313  */
314 static __always_inline void slab_lock(struct page *page)
315 {
316         VM_BUG_ON_PAGE(PageTail(page), page);
317         bit_spin_lock(PG_locked, &page->flags);
318 }
319 
320 static __always_inline void slab_unlock(struct page *page)
321 {
322         VM_BUG_ON_PAGE(PageTail(page), page);
323         __bit_spin_unlock(PG_locked, &page->flags);
324 }
325 
326 static inline void set_page_slub_counters(struct page *page, unsigned long counters_new)
327 {
328         struct page tmp;
329         tmp.counters = counters_new;
330         /*
331          * page->counters can cover frozen/inuse/objects as well
332          * as page->_count.  If we assign to ->counters directly
333          * we run the risk of losing updates to page->_count, so
334          * be careful and only assign to the fields we need.
335          */
336         page->frozen  = tmp.frozen;
337         page->inuse   = tmp.inuse;
338         page->objects = tmp.objects;
339 }
340 
341 /* Interrupts must be disabled (for the fallback code to work right) */
342 static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
343                 void *freelist_old, unsigned long counters_old,
344                 void *freelist_new, unsigned long counters_new,
345                 const char *n)
346 {
347         VM_BUG_ON(!irqs_disabled());
348 #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
349     defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
350         if (s->flags & __CMPXCHG_DOUBLE) {
351                 if (cmpxchg_double(&page->freelist, &page->counters,
352                                    freelist_old, counters_old,
353                                    freelist_new, counters_new))
354                         return true;
355         } else
356 #endif
357         {
358                 slab_lock(page);
359                 if (page->freelist == freelist_old &&
360                                         page->counters == counters_old) {
361                         page->freelist = freelist_new;
362                         set_page_slub_counters(page, counters_new);
363                         slab_unlock(page);
364                         return true;
365                 }
366                 slab_unlock(page);
367         }
368 
369         cpu_relax();
370         stat(s, CMPXCHG_DOUBLE_FAIL);
371 
372 #ifdef SLUB_DEBUG_CMPXCHG
373         pr_info("%s %s: cmpxchg double redo ", n, s->name);
374 #endif
375 
376         return false;
377 }
378 
379 static inline bool cmpxchg_double_slab(struct kmem_cache *s, struct page *page,
380                 void *freelist_old, unsigned long counters_old,
381                 void *freelist_new, unsigned long counters_new,
382                 const char *n)
383 {
384 #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
385     defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
386         if (s->flags & __CMPXCHG_DOUBLE) {
387                 if (cmpxchg_double(&page->freelist, &page->counters,
388                                    freelist_old, counters_old,
389                                    freelist_new, counters_new))
390                         return true;
391         } else
392 #endif
393         {
394                 unsigned long flags;
395 
396                 local_irq_save(flags);
397                 slab_lock(page);
398                 if (page->freelist == freelist_old &&
399                                         page->counters == counters_old) {
400                         page->freelist = freelist_new;
401                         set_page_slub_counters(page, counters_new);
402                         slab_unlock(page);
403                         local_irq_restore(flags);
404                         return true;
405                 }
406                 slab_unlock(page);
407                 local_irq_restore(flags);
408         }
409 
410         cpu_relax();
411         stat(s, CMPXCHG_DOUBLE_FAIL);
412 
413 #ifdef SLUB_DEBUG_CMPXCHG
414         pr_info("%s %s: cmpxchg double redo ", n, s->name);
415 #endif
416 
417         return false;
418 }
419 
420 #ifdef CONFIG_SLUB_DEBUG
421 /*
422  * Determine a map of object in use on a page.
423  *
424  * Node listlock must be held to guarantee that the page does
425  * not vanish from under us.
426  */
427 static void get_map(struct kmem_cache *s, struct page *page, unsigned long *map)
428 {
429         void *p;
430         void *addr = page_address(page);
431 
432         for (p = page->freelist; p; p = get_freepointer(s, p))
433                 set_bit(slab_index(p, s, addr), map);
434 }
435 
436 static inline int size_from_object(struct kmem_cache *s)
437 {
438         if (s->flags & SLAB_RED_ZONE)
439                 return s->size - s->red_left_pad;
440 
441         return s->size;
442 }
443 
444 static inline void *restore_red_left(struct kmem_cache *s, void *p)
445 {
446         if (s->flags & SLAB_RED_ZONE)
447                 p -= s->red_left_pad;
448 
449         return p;
450 }
451 
452 /*
453  * Debug settings:
454  */
455 #if defined(CONFIG_SLUB_DEBUG_ON)
456 static int slub_debug = DEBUG_DEFAULT_FLAGS;
457 #elif defined(CONFIG_KASAN)
458 static int slub_debug = SLAB_STORE_USER;
459 #else
460 static int slub_debug;
461 #endif
462 
463 static char *slub_debug_slabs;
464 static int disable_higher_order_debug;
465 
466 /*
467  * slub is about to manipulate internal object metadata.  This memory lies
468  * outside the range of the allocated object, so accessing it would normally
469  * be reported by kasan as a bounds error.  metadata_access_enable() is used
470  * to tell kasan that these accesses are OK.
471  */
472 static inline void metadata_access_enable(void)
473 {
474         kasan_disable_current();
475 }
476 
477 static inline void metadata_access_disable(void)
478 {
479         kasan_enable_current();
480 }
481 
482 /*
483  * Object debugging
484  */
485 
486 /* Verify that a pointer has an address that is valid within a slab page */
487 static inline int check_valid_pointer(struct kmem_cache *s,
488                                 struct page *page, void *object)
489 {
490         void *base;
491 
492         if (!object)
493                 return 1;
494 
495         base = page_address(page);
496         object = restore_red_left(s, object);
497         if (object < base || object >= base + page->objects * s->size ||
498                 (object - base) % s->size) {
499                 return 0;
500         }
501 
502         return 1;
503 }
504 
505 static void print_section(char *text, u8 *addr, unsigned int length)
506 {
507         metadata_access_enable();
508         print_hex_dump(KERN_ERR, text, DUMP_PREFIX_ADDRESS, 16, 1, addr,
509                         length, 1);
510         metadata_access_disable();
511 }
512 
513 static struct track *get_track(struct kmem_cache *s, void *object,
514         enum track_item alloc)
515 {
516         struct track *p;
517 
518         if (s->offset)
519                 p = object + s->offset + sizeof(void *);
520         else
521                 p = object + s->inuse;
522 
523         return p + alloc;
524 }
525 
526 static void set_track(struct kmem_cache *s, void *object,
527                         enum track_item alloc, unsigned long addr)
528 {
529         struct track *p = get_track(s, object, alloc);
530 
531         if (addr) {
532 #ifdef CONFIG_STACKTRACE
533                 struct stack_trace trace;
534                 int i;
535 
536                 trace.nr_entries = 0;
537                 trace.max_entries = TRACK_ADDRS_COUNT;
538                 trace.entries = p->addrs;
539                 trace.skip = 3;
540                 metadata_access_enable();
541                 save_stack_trace(&trace);
542                 metadata_access_disable();
543 
544                 /* See rant in lockdep.c */
545                 if (trace.nr_entries != 0 &&
546                     trace.entries[trace.nr_entries - 1] == ULONG_MAX)
547                         trace.nr_entries--;
548 
549                 for (i = trace.nr_entries; i < TRACK_ADDRS_COUNT; i++)
550                         p->addrs[i] = 0;
551 #endif
552                 p->addr = addr;
553                 p->cpu = smp_processor_id();
554                 p->pid = current->pid;
555                 p->when = jiffies;
556         } else
557                 memset(p, 0, sizeof(struct track));
558 }
559 
560 static void init_tracking(struct kmem_cache *s, void *object)
561 {
562         if (!(s->flags & SLAB_STORE_USER))
563                 return;
564 
565         set_track(s, object, TRACK_FREE, 0UL);
566         set_track(s, object, TRACK_ALLOC, 0UL);
567 }
568 
569 static void print_track(const char *s, struct track *t)
570 {
571         if (!t->addr)
572                 return;
573 
574         pr_err("INFO: %s in %pS age=%lu cpu=%u pid=%d\n",
575                s, (void *)t->addr, jiffies - t->when, t->cpu, t->pid);
576 #ifdef CONFIG_STACKTRACE
577         {
578                 int i;
579                 for (i = 0; i < TRACK_ADDRS_COUNT; i++)
580                         if (t->addrs[i])
581                                 pr_err("\t%pS\n", (void *)t->addrs[i]);
582                         else
583                                 break;
584         }
585 #endif
586 }
587 
588 static void print_tracking(struct kmem_cache *s, void *object)
589 {
590         if (!(s->flags & SLAB_STORE_USER))
591                 return;
592 
593         print_track("Allocated", get_track(s, object, TRACK_ALLOC));
594         print_track("Freed", get_track(s, object, TRACK_FREE));
595 }
596 
597 static void print_page_info(struct page *page)
598 {
599         pr_err("INFO: Slab 0x%p objects=%u used=%u fp=0x%p flags=0x%04lx\n",
600                page, page->objects, page->inuse, page->freelist, page->flags);
601 
602 }
603 
604 static void slab_bug(struct kmem_cache *s, char *fmt, ...)
605 {
606         struct va_format vaf;
607         va_list args;
608 
609         va_start(args, fmt);
610         vaf.fmt = fmt;
611         vaf.va = &args;
612         pr_err("=============================================================================\n");
613         pr_err("BUG %s (%s): %pV\n", s->name, print_tainted(), &vaf);
614         pr_err("-----------------------------------------------------------------------------\n\n");
615 
616         add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
617         va_end(args);
618 }
619 
620 static void slab_fix(struct kmem_cache *s, char *fmt, ...)
621 {
622         struct va_format vaf;
623         va_list args;
624 
625         va_start(args, fmt);
626         vaf.fmt = fmt;
627         vaf.va = &args;
628         pr_err("FIX %s: %pV\n", s->name, &vaf);
629         va_end(args);
630 }
631 
632 static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p)
633 {
634         unsigned int off;       /* Offset of last byte */
635         u8 *addr = page_address(page);
636 
637         print_tracking(s, p);
638 
639         print_page_info(page);
640 
641         pr_err("INFO: Object 0x%p @offset=%tu fp=0x%p\n\n",
642                p, p - addr, get_freepointer(s, p));
643 
644         if (s->flags & SLAB_RED_ZONE)
645                 print_section("Redzone ", p - s->red_left_pad, s->red_left_pad);
646         else if (p > addr + 16)
647                 print_section("Bytes b4 ", p - 16, 16);
648 
649         print_section("Object ", p, min_t(unsigned long, s->object_size,
650                                 PAGE_SIZE));
651         if (s->flags & SLAB_RED_ZONE)
652                 print_section("Redzone ", p + s->object_size,
653                         s->inuse - s->object_size);
654 
655         if (s->offset)
656                 off = s->offset + sizeof(void *);
657         else
658                 off = s->inuse;
659 
660         if (s->flags & SLAB_STORE_USER)
661                 off += 2 * sizeof(struct track);
662 
663         if (off != size_from_object(s))
664                 /* Beginning of the filler is the free pointer */
665                 print_section("Padding ", p + off, size_from_object(s) - off);
666 
667         dump_stack();
668 }
669 
670 void object_err(struct kmem_cache *s, struct page *page,
671                         u8 *object, char *reason)
672 {
673         slab_bug(s, "%s", reason);
674         print_trailer(s, page, object);
675 }
676 
677 static void slab_err(struct kmem_cache *s, struct page *page,
678                         const char *fmt, ...)
679 {
680         va_list args;
681         char buf[100];
682 
683         va_start(args, fmt);
684         vsnprintf(buf, sizeof(buf), fmt, args);
685         va_end(args);
686         slab_bug(s, "%s", buf);
687         print_page_info(page);
688         dump_stack();
689 }
690 
691 static void init_object(struct kmem_cache *s, void *object, u8 val)
692 {
693         u8 *p = object;
694 
695         if (s->flags & SLAB_RED_ZONE)
696                 memset(p - s->red_left_pad, val, s->red_left_pad);
697 
698         if (s->flags & __OBJECT_POISON) {
699                 memset(p, POISON_FREE, s->object_size - 1);
700                 p[s->object_size - 1] = POISON_END;
701         }
702 
703         if (s->flags & SLAB_RED_ZONE)
704                 memset(p + s->object_size, val, s->inuse - s->object_size);
705 }
706 
707 static void restore_bytes(struct kmem_cache *s, char *message, u8 data,
708                                                 void *from, void *to)
709 {
710         slab_fix(s, "Restoring 0x%p-0x%p=0x%x\n", from, to - 1, data);
711         memset(from, data, to - from);
712 }
713 
714 static int check_bytes_and_report(struct kmem_cache *s, struct page *page,
715                         u8 *object, char *what,
716                         u8 *start, unsigned int value, unsigned int bytes)
717 {
718         u8 *fault;
719         u8 *end;
720 
721         metadata_access_enable();
722         fault = memchr_inv(start, value, bytes);
723         metadata_access_disable();
724         if (!fault)
725                 return 1;
726 
727         end = start + bytes;
728         while (end > fault && end[-1] == value)
729                 end--;
730 
731         slab_bug(s, "%s overwritten", what);
732         pr_err("INFO: 0x%p-0x%p. First byte 0x%x instead of 0x%x\n",
733                                         fault, end - 1, fault[0], value);
734         print_trailer(s, page, object);
735 
736         restore_bytes(s, what, value, fault, end);
737         return 0;
738 }
739 
740 /*
741  * Object layout:
742  *
743  * object address
744  *      Bytes of the object to be managed.
745  *      If the freepointer may overlay the object then the free
746  *      pointer is the first word of the object.
747  *
748  *      Poisoning uses 0x6b (POISON_FREE) and the last byte is
749  *      0xa5 (POISON_END)
750  *
751  * object + s->object_size
752  *      Padding to reach word boundary. This is also used for Redzoning.
753  *      Padding is extended by another word if Redzoning is enabled and
754  *      object_size == inuse.
755  *
756  *      We fill with 0xbb (RED_INACTIVE) for inactive objects and with
757  *      0xcc (RED_ACTIVE) for objects in use.
758  *
759  * object + s->inuse
760  *      Meta data starts here.
761  *
762  *      A. Free pointer (if we cannot overwrite object on free)
763  *      B. Tracking data for SLAB_STORE_USER
764  *      C. Padding to reach required alignment boundary or at mininum
765  *              one word if debugging is on to be able to detect writes
766  *              before the word boundary.
767  *
768  *      Padding is done using 0x5a (POISON_INUSE)
769  *
770  * object + s->size
771  *      Nothing is used beyond s->size.
772  *
773  * If slabcaches are merged then the object_size and inuse boundaries are mostly
774  * ignored. And therefore no slab options that rely on these boundaries
775  * may be used with merged slabcaches.
776  */
777 
778 static int check_pad_bytes(struct kmem_cache *s, struct page *page, u8 *p)
779 {
780         unsigned long off = s->inuse;   /* The end of info */
781 
782         if (s->offset)
783                 /* Freepointer is placed after the object. */
784                 off += sizeof(void *);
785 
786         if (s->flags & SLAB_STORE_USER)
787                 /* We also have user information there */
788                 off += 2 * sizeof(struct track);
789 
790         if (size_from_object(s) == off)
791                 return 1;
792 
793         return check_bytes_and_report(s, page, p, "Object padding",
794                         p + off, POISON_INUSE, size_from_object(s) - off);
795 }
796 
797 /* Check the pad bytes at the end of a slab page */
798 static int slab_pad_check(struct kmem_cache *s, struct page *page)
799 {
800         u8 *start;
801         u8 *fault;
802         u8 *end;
803         int length;
804         int remainder;
805 
806         if (!(s->flags & SLAB_POISON))
807                 return 1;
808 
809         start = page_address(page);
810         length = (PAGE_SIZE << compound_order(page)) - s->reserved;
811         end = start + length;
812         remainder = length % s->size;
813         if (!remainder)
814                 return 1;
815 
816         metadata_access_enable();
817         fault = memchr_inv(end - remainder, POISON_INUSE, remainder);
818         metadata_access_disable();
819         if (!fault)
820                 return 1;
821         while (end > fault && end[-1] == POISON_INUSE)
822                 end--;
823 
824         slab_err(s, page, "Padding overwritten. 0x%p-0x%p", fault, end - 1);
825         print_section("Padding ", end - remainder, remainder);
826 
827         restore_bytes(s, "slab padding", POISON_INUSE, end - remainder, end);
828         return 0;
829 }
830 
831 static int check_object(struct kmem_cache *s, struct page *page,
832                                         void *object, u8 val)
833 {
834         u8 *p = object;
835         u8 *endobject = object + s->object_size;
836 
837         if (s->flags & SLAB_RED_ZONE) {
838                 if (!check_bytes_and_report(s, page, object, "Redzone",
839                         object - s->red_left_pad, val, s->red_left_pad))
840                         return 0;
841 
842                 if (!check_bytes_and_report(s, page, object, "Redzone",
843                         endobject, val, s->inuse - s->object_size))
844                         return 0;
845         } else {
846                 if ((s->flags & SLAB_POISON) && s->object_size < s->inuse) {
847                         check_bytes_and_report(s, page, p, "Alignment padding",
848                                 endobject, POISON_INUSE,
849                                 s->inuse - s->object_size);
850                 }
851         }
852 
853         if (s->flags & SLAB_POISON) {
854                 if (val != SLUB_RED_ACTIVE && (s->flags & __OBJECT_POISON) &&
855                         (!check_bytes_and_report(s, page, p, "Poison", p,
856                                         POISON_FREE, s->object_size - 1) ||
857                          !check_bytes_and_report(s, page, p, "Poison",
858                                 p + s->object_size - 1, POISON_END, 1)))
859                         return 0;
860                 /*
861                  * check_pad_bytes cleans up on its own.
862                  */
863                 check_pad_bytes(s, page, p);
864         }
865 
866         if (!s->offset && val == SLUB_RED_ACTIVE)
867                 /*
868                  * Object and freepointer overlap. Cannot check
869                  * freepointer while object is allocated.
870                  */
871                 return 1;
872 
873         /* Check free pointer validity */
874         if (!check_valid_pointer(s, page, get_freepointer(s, p))) {
875                 object_err(s, page, p, "Freepointer corrupt");
876                 /*
877                  * No choice but to zap it and thus lose the remainder
878                  * of the free objects in this slab. May cause
879                  * another error because the object count is now wrong.
880                  */
881                 set_freepointer(s, p, NULL);
882                 return 0;
883         }
884         return 1;
885 }
886 
887 static int check_slab(struct kmem_cache *s, struct page *page)
888 {
889         int maxobj;
890 
891         VM_BUG_ON(!irqs_disabled());
892 
893         if (!PageSlab(page)) {
894                 slab_err(s, page, "Not a valid slab page");
895                 return 0;
896         }
897 
898         maxobj = order_objects(compound_order(page), s->size, s->reserved);
899         if (page->objects > maxobj) {
900                 slab_err(s, page, "objects %u > max %u",
901                         page->objects, maxobj);
902                 return 0;
903         }
904         if (page->inuse > page->objects) {
905                 slab_err(s, page, "inuse %u > max %u",
906                         page->inuse, page->objects);
907                 return 0;
908         }
909         /* Slab_pad_check fixes things up after itself */
910         slab_pad_check(s, page);
911         return 1;
912 }
913 
914 /*
915  * Determine if a certain object on a page is on the freelist. Must hold the
916  * slab lock to guarantee that the chains are in a consistent state.
917  */
918 static int on_freelist(struct kmem_cache *s, struct page *page, void *search)
919 {
920         int nr = 0;
921         void *fp;
922         void *object = NULL;
923         int max_objects;
924 
925         fp = page->freelist;
926         while (fp && nr <= page->objects) {
927                 if (fp == search)
928                         return 1;
929                 if (!check_valid_pointer(s, page, fp)) {
930                         if (object) {
931                                 object_err(s, page, object,
932                                         "Freechain corrupt");
933                                 set_freepointer(s, object, NULL);
934                         } else {
935                                 slab_err(s, page, "Freepointer corrupt");
936                                 page->freelist = NULL;
937                                 page->inuse = page->objects;
938                                 slab_fix(s, "Freelist cleared");
939                                 return 0;
940                         }
941                         break;
942                 }
943                 object = fp;
944                 fp = get_freepointer(s, object);
945                 nr++;
946         }
947 
948         max_objects = order_objects(compound_order(page), s->size, s->reserved);
949         if (max_objects > MAX_OBJS_PER_PAGE)
950                 max_objects = MAX_OBJS_PER_PAGE;
951 
952         if (page->objects != max_objects) {
953                 slab_err(s, page, "Wrong number of objects. Found %d but should be %d",
954                          page->objects, max_objects);
955                 page->objects = max_objects;
956                 slab_fix(s, "Number of objects adjusted.");
957         }
958         if (page->inuse != page->objects - nr) {
959                 slab_err(s, page, "Wrong object count. Counter is %d but counted were %d",
960                          page->inuse, page->objects - nr);
961                 page->inuse = page->objects - nr;
962                 slab_fix(s, "Object count adjusted.");
963         }
964         return search == NULL;
965 }
966 
967 static void trace(struct kmem_cache *s, struct page *page, void *object,
968                                                                 int alloc)
969 {
970         if (s->flags & SLAB_TRACE) {
971                 pr_info("TRACE %s %s 0x%p inuse=%d fp=0x%p\n",
972                         s->name,
973                         alloc ? "alloc" : "free",
974                         object, page->inuse,
975                         page->freelist);
976 
977                 if (!alloc)
978                         print_section("Object ", (void *)object,
979                                         s->object_size);
980 
981                 dump_stack();
982         }
983 }
984 
985 /*
986  * Tracking of fully allocated slabs for debugging purposes.
987  */
988 static void add_full(struct kmem_cache *s,
989         struct kmem_cache_node *n, struct page *page)
990 {
991         if (!(s->flags & SLAB_STORE_USER))
992                 return;
993 
994         lockdep_assert_held(&n->list_lock);
995         list_add(&page->lru, &n->full);
996 }
997 
998 static void remove_full(struct kmem_cache *s, struct kmem_cache_node *n, struct page *page)
999 {
1000         if (!(s->flags & SLAB_STORE_USER))
1001                 return;
1002 
1003         lockdep_assert_held(&n->list_lock);
1004         list_del(&page->lru);
1005 }
1006 
1007 /* Tracking of the number of slabs for debugging purposes */
1008 static inline unsigned long slabs_node(struct kmem_cache *s, int node)
1009 {
1010         struct kmem_cache_node *n = get_node(s, node);
1011 
1012         return atomic_long_read(&n->nr_slabs);
1013 }
1014 
1015 static inline unsigned long node_nr_slabs(struct kmem_cache_node *n)
1016 {
1017         return atomic_long_read(&n->nr_slabs);
1018 }
1019 
1020 static inline void inc_slabs_node(struct kmem_cache *s, int node, int objects)
1021 {
1022         struct kmem_cache_node *n = get_node(s, node);
1023 
1024         /*
1025          * May be called early in order to allocate a slab for the
1026          * kmem_cache_node structure. Solve the chicken-egg
1027          * dilemma by deferring the increment of the count during
1028          * bootstrap (see early_kmem_cache_node_alloc).
1029          */
1030         if (likely(n)) {
1031                 atomic_long_inc(&n->nr_slabs);
1032                 atomic_long_add(objects, &n->total_objects);
1033         }
1034 }
1035 static inline void dec_slabs_node(struct kmem_cache *s, int node, int objects)
1036 {
1037         struct kmem_cache_node *n = get_node(s, node);
1038 
1039         atomic_long_dec(&n->nr_slabs);
1040         atomic_long_sub(objects, &n->total_objects);
1041 }
1042 
1043 /* Object debug checks for alloc/free paths */
1044 static void setup_object_debug(struct kmem_cache *s, struct page *page,
1045                                                                 void *object)
1046 {
1047         if (!(s->flags & (SLAB_STORE_USER|SLAB_RED_ZONE|__OBJECT_POISON)))
1048                 return;
1049 
1050         init_object(s, object, SLUB_RED_INACTIVE);
1051         init_tracking(s, object);
1052 }
1053 
1054 static inline int alloc_consistency_checks(struct kmem_cache *s,
1055                                         struct page *page,
1056                                         void *object, unsigned long addr)
1057 {
1058         if (!check_slab(s, page))
1059                 return 0;
1060 
1061         if (!check_valid_pointer(s, page, object)) {
1062                 object_err(s, page, object, "Freelist Pointer check fails");
1063                 return 0;
1064         }
1065 
1066         if (!check_object(s, page, object, SLUB_RED_INACTIVE))
1067                 return 0;
1068 
1069         return 1;
1070 }
1071 
1072 static noinline int alloc_debug_processing(struct kmem_cache *s,
1073                                         struct page *page,
1074                                         void *object, unsigned long addr)
1075 {
1076         if (s->flags & SLAB_CONSISTENCY_CHECKS) {
1077                 if (!alloc_consistency_checks(s, page, object, addr))
1078                         goto bad;
1079         }
1080 
1081         /* Success perform special debug activities for allocs */
1082         if (s->flags & SLAB_STORE_USER)
1083                 set_track(s, object, TRACK_ALLOC, addr);
1084         trace(s, page, object, 1);
1085         init_object(s, object, SLUB_RED_ACTIVE);
1086         return 1;
1087 
1088 bad:
1089         if (PageSlab(page)) {
1090                 /*
1091                  * If this is a slab page then lets do the best we can
1092                  * to avoid issues in the future. Marking all objects
1093                  * as used avoids touching the remaining objects.
1094                  */
1095                 slab_fix(s, "Marking all objects used");
1096                 page->inuse = page->objects;
1097                 page->freelist = NULL;
1098         }
1099         return 0;
1100 }
1101 
1102 static inline int free_consistency_checks(struct kmem_cache *s,
1103                 struct page *page, void *object, unsigned long addr)
1104 {
1105         if (!check_valid_pointer(s, page, object)) {
1106                 slab_err(s, page, "Invalid object pointer 0x%p", object);
1107                 return 0;
1108         }
1109 
1110         if (on_freelist(s, page, object)) {
1111                 object_err(s, page, object, "Object already free");
1112                 return 0;
1113         }
1114 
1115         if (!check_object(s, page, object, SLUB_RED_ACTIVE))
1116                 return 0;
1117 
1118         if (unlikely(s != page->slab_cache)) {
1119                 if (!PageSlab(page)) {
1120                         slab_err(s, page, "Attempt to free object(0x%p) outside of slab",
1121                                  object);
1122                 } else if (!page->slab_cache) {
1123                         pr_err("SLUB <none>: no slab for object 0x%p.\n",
1124                                object);
1125                         dump_stack();
1126                 } else
1127                         object_err(s, page, object,
1128                                         "page slab pointer corrupt.");
1129                 return 0;
1130         }
1131         return 1;
1132 }
1133 
1134 /* Supports checking bulk free of a constructed freelist */
1135 static noinline int free_debug_processing(
1136         struct kmem_cache *s, struct page *page,
1137         void *head, void *tail, int bulk_cnt,
1138         unsigned long addr)
1139 {
1140         struct kmem_cache_node *n = get_node(s, page_to_nid(page));
1141         void *object = head;
1142         int cnt = 0;
1143         unsigned long uninitialized_var(flags);
1144         int ret = 0;
1145 
1146         spin_lock_irqsave(&n->list_lock, flags);
1147         slab_lock(page);
1148 
1149         if (s->flags & SLAB_CONSISTENCY_CHECKS) {
1150                 if (!check_slab(s, page))
1151                         goto out;
1152         }
1153 
1154 next_object:
1155         cnt++;
1156 
1157         if (s->flags & SLAB_CONSISTENCY_CHECKS) {
1158                 if (!free_consistency_checks(s, page, object, addr))
1159                         goto out;
1160         }
1161 
1162         if (s->flags & SLAB_STORE_USER)
1163                 set_track(s, object, TRACK_FREE, addr);
1164         trace(s, page, object, 0);
1165         /* Freepointer not overwritten by init_object(), SLAB_POISON moved it */
1166         init_object(s, object, SLUB_RED_INACTIVE);
1167 
1168         /* Reached end of constructed freelist yet? */
1169         if (object != tail) {
1170                 object = get_freepointer(s, object);
1171                 goto next_object;
1172         }
1173         ret = 1;
1174 
1175 out:
1176         if (cnt != bulk_cnt)
1177                 slab_err(s, page, "Bulk freelist count(%d) invalid(%d)\n",
1178                          bulk_cnt, cnt);
1179 
1180         slab_unlock(page);
1181         spin_unlock_irqrestore(&n->list_lock, flags);
1182         if (!ret)
1183                 slab_fix(s, "Object at 0x%p not freed", object);
1184         return ret;
1185 }
1186 
1187 static int __init setup_slub_debug(char *str)
1188 {
1189         slub_debug = DEBUG_DEFAULT_FLAGS;
1190         if (*str++ != '=' || !*str)
1191                 /*
1192                  * No options specified. Switch on full debugging.
1193                  */
1194                 goto out;
1195 
1196         if (*str == ',')
1197                 /*
1198                  * No options but restriction on slabs. This means full
1199                  * debugging for slabs matching a pattern.
1200                  */
1201                 goto check_slabs;
1202 
1203         slub_debug = 0;
1204         if (*str == '-')
1205                 /*
1206                  * Switch off all debugging measures.
1207                  */
1208                 goto out;
1209 
1210         /*
1211          * Determine which debug features should be switched on
1212          */
1213         for (; *str && *str != ','; str++) {
1214                 switch (tolower(*str)) {
1215                 case 'f':
1216                         slub_debug |= SLAB_CONSISTENCY_CHECKS;
1217                         break;
1218                 case 'z':
1219                         slub_debug |= SLAB_RED_ZONE;
1220                         break;
1221                 case 'p':
1222                         slub_debug |= SLAB_POISON;
1223                         break;
1224                 case 'u':
1225                         slub_debug |= SLAB_STORE_USER;
1226                         break;
1227                 case 't':
1228                         slub_debug |= SLAB_TRACE;
1229                         break;
1230                 case 'a':
1231                         slub_debug |= SLAB_FAILSLAB;
1232                         break;
1233                 case 'o':
1234                         /*
1235                          * Avoid enabling debugging on caches if its minimum
1236                          * order would increase as a result.
1237                          */
1238                         disable_higher_order_debug = 1;
1239                         break;
1240                 default:
1241                         pr_err("slub_debug option '%c' unknown. skipped\n",
1242                                *str);
1243                 }
1244         }
1245 
1246 check_slabs:
1247         if (*str == ',')
1248                 slub_debug_slabs = str + 1;
1249 out:
1250         return 1;
1251 }
1252 
1253 __setup("slub_debug", setup_slub_debug);
1254 
1255 unsigned long kmem_cache_flags(unsigned long object_size,
1256         unsigned long flags, const char *name,
1257         void (*ctor)(void *))
1258 {
1259         /*
1260          * Enable debugging if selected on the kernel commandline.
1261          */
1262         if (slub_debug && (!slub_debug_slabs || (name &&
1263                 !strncmp(slub_debug_slabs, name, strlen(slub_debug_slabs)))))
1264                 flags |= slub_debug;
1265 
1266         return flags;
1267 }
1268 #else /* !CONFIG_SLUB_DEBUG */
1269 static inline void setup_object_debug(struct kmem_cache *s,
1270                         struct page *page, void *object) {}
1271 
1272 static inline int alloc_debug_processing(struct kmem_cache *s,
1273         struct page *page, void *object, unsigned long addr) { return 0; }
1274 
1275 static inline int free_debug_processing(
1276         struct kmem_cache *s, struct page *page,
1277         void *head, void *tail, int bulk_cnt,
1278         unsigned long addr) { return 0; }
1279 
1280 static inline int slab_pad_check(struct kmem_cache *s, struct page *page)
1281                         { return 1; }
1282 static inline int check_object(struct kmem_cache *s, struct page *page,
1283                         void *object, u8 val) { return 1; }
1284 static inline void add_full(struct kmem_cache *s, struct kmem_cache_node *n,
1285                                         struct page *page) {}
1286 static inline void remove_full(struct kmem_cache *s, struct kmem_cache_node *n,
1287                                         struct page *page) {}
1288 unsigned long kmem_cache_flags(unsigned long object_size,
1289         unsigned long flags, const char *name,
1290         void (*ctor)(void *))
1291 {
1292         return flags;
1293 }
1294 #define slub_debug 0
1295 
1296 #define disable_higher_order_debug 0
1297 
1298 static inline unsigned long slabs_node(struct kmem_cache *s, int node)
1299                                                         { return 0; }
1300 static inline unsigned long node_nr_slabs(struct kmem_cache_node *n)
1301                                                         { return 0; }
1302 static inline void inc_slabs_node(struct kmem_cache *s, int node,
1303                                                         int objects) {}
1304 static inline void dec_slabs_node(struct kmem_cache *s, int node,
1305                                                         int objects) {}
1306 
1307 #endif /* CONFIG_SLUB_DEBUG */
1308 
1309 /*
1310  * Hooks for other subsystems that check memory allocations. In a typical
1311  * production configuration these hooks all should produce no code at all.
1312  */
1313 static inline void kmalloc_large_node_hook(void *ptr, size_t size, gfp_t flags)
1314 {
1315         kmemleak_alloc(ptr, size, 1, flags);
1316         kasan_kmalloc_large(ptr, size, flags);
1317 }
1318 
1319 static inline void kfree_hook(const void *x)
1320 {
1321         kmemleak_free(x);
1322         kasan_kfree_large(x);
1323 }
1324 
1325 static inline void slab_free_hook(struct kmem_cache *s, void *x)
1326 {
1327         kmemleak_free_recursive(x, s->flags);
1328 
1329         /*
1330          * Trouble is that we may no longer disable interrupts in the fast path
1331          * So in order to make the debug calls that expect irqs to be
1332          * disabled we need to disable interrupts temporarily.
1333          */
1334 #if defined(CONFIG_KMEMCHECK) || defined(CONFIG_LOCKDEP)
1335         {
1336                 unsigned long flags;
1337 
1338                 local_irq_save(flags);
1339                 kmemcheck_slab_free(s, x, s->object_size);
1340                 debug_check_no_locks_freed(x, s->object_size);
1341                 local_irq_restore(flags);
1342         }
1343 #endif
1344         if (!(s->flags & SLAB_DEBUG_OBJECTS))
1345                 debug_check_no_obj_freed(x, s->object_size);
1346 
1347         kasan_slab_free(s, x);
1348 }
1349 
1350 static inline void slab_free_freelist_hook(struct kmem_cache *s,
1351                                            void *head, void *tail)
1352 {
1353 /*
1354  * Compiler cannot detect this function can be removed if slab_free_hook()
1355  * evaluates to nothing.  Thus, catch all relevant config debug options here.
1356  */
1357 #if defined(CONFIG_KMEMCHECK) ||                \
1358         defined(CONFIG_LOCKDEP) ||              \
1359         defined(CONFIG_DEBUG_KMEMLEAK) ||       \
1360         defined(CONFIG_DEBUG_OBJECTS_FREE) ||   \
1361         defined(CONFIG_KASAN)
1362 
1363         void *object = head;
1364         void *tail_obj = tail ? : head;
1365 
1366         do {
1367                 slab_free_hook(s, object);
1368         } while ((object != tail_obj) &&
1369                  (object = get_freepointer(s, object)));
1370 #endif
1371 }
1372 
1373 static void setup_object(struct kmem_cache *s, struct page *page,
1374                                 void *object)
1375 {
1376         setup_object_debug(s, page, object);
1377         if (unlikely(s->ctor)) {
1378                 kasan_unpoison_object_data(s, object);
1379                 s->ctor(object);
1380                 kasan_poison_object_data(s, object);
1381         }
1382 }
1383 
1384 /*
1385  * Slab allocation and freeing
1386  */
1387 static inline struct page *alloc_slab_page(struct kmem_cache *s,
1388                 gfp_t flags, int node, struct kmem_cache_order_objects oo)
1389 {
1390         struct page *page;
1391         int order = oo_order(oo);
1392 
1393         flags |= __GFP_NOTRACK;
1394 
1395         if (node == NUMA_NO_NODE)
1396                 page = alloc_pages(flags, order);
1397         else
1398                 page = __alloc_pages_node(node, flags, order);
1399 
1400         if (page && memcg_charge_slab(page, flags, order, s)) {
1401                 __free_pages(page, order);
1402                 page = NULL;
1403         }
1404 
1405         return page;
1406 }
1407 
1408 static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node)
1409 {
1410         struct page *page;
1411         struct kmem_cache_order_objects oo = s->oo;
1412         gfp_t alloc_gfp;
1413         void *start, *p;
1414         int idx, order;
1415 
1416         flags &= gfp_allowed_mask;
1417 
1418         if (gfpflags_allow_blocking(flags))
1419                 local_irq_enable();
1420 
1421         flags |= s->allocflags;
1422 
1423         /*
1424          * Let the initial higher-order allocation fail under memory pressure
1425          * so we fall-back to the minimum order allocation.
1426          */
1427         alloc_gfp = (flags | __GFP_NOWARN | __GFP_NORETRY) & ~__GFP_NOFAIL;
1428         if ((alloc_gfp & __GFP_DIRECT_RECLAIM) && oo_order(oo) > oo_order(s->min))
1429                 alloc_gfp = (alloc_gfp | __GFP_NOMEMALLOC) & ~(__GFP_RECLAIM|__GFP_NOFAIL);
1430 
1431         page = alloc_slab_page(s, alloc_gfp, node, oo);
1432         if (unlikely(!page)) {
1433                 oo = s->min;
1434                 alloc_gfp = flags;
1435                 /*
1436                  * Allocation may have failed due to fragmentation.
1437                  * Try a lower order alloc if possible
1438                  */
1439                 page = alloc_slab_page(s, alloc_gfp, node, oo);
1440                 if (unlikely(!page))
1441                         goto out;
1442                 stat(s, ORDER_FALLBACK);
1443         }
1444 
1445         if (kmemcheck_enabled &&
1446             !(s->flags & (SLAB_NOTRACK | DEBUG_DEFAULT_FLAGS))) {
1447                 int pages = 1 << oo_order(oo);
1448 
1449                 kmemcheck_alloc_shadow(page, oo_order(oo), alloc_gfp, node);
1450 
1451                 /*
1452                  * Objects from caches that have a constructor don't get
1453                  * cleared when they're allocated, so we need to do it here.
1454                  */
1455                 if (s->ctor)
1456                         kmemcheck_mark_uninitialized_pages(page, pages);
1457                 else
1458                         kmemcheck_mark_unallocated_pages(page, pages);
1459         }
1460 
1461         page->objects = oo_objects(oo);
1462 
1463         order = compound_order(page);
1464         page->slab_cache = s;
1465         __SetPageSlab(page);
1466         if (page_is_pfmemalloc(page))
1467                 SetPageSlabPfmemalloc(page);
1468 
1469         start = page_address(page);
1470 
1471         if (unlikely(s->flags & SLAB_POISON))
1472                 memset(start, POISON_INUSE, PAGE_SIZE << order);
1473 
1474         kasan_poison_slab(page);
1475 
1476         for_each_object_idx(p, idx, s, start, page->objects) {
1477                 setup_object(s, page, p);
1478                 if (likely(idx < page->objects))
1479                         set_freepointer(s, p, p + s->size);
1480                 else
1481                         set_freepointer(s, p, NULL);
1482         }
1483 
1484         page->freelist = fixup_red_left(s, start);
1485         page->inuse = page->objects;
1486         page->frozen = 1;
1487 
1488 out:
1489         if (gfpflags_allow_blocking(flags))
1490                 local_irq_disable();
1491         if (!page)
1492                 return NULL;
1493 
1494         mod_zone_page_state(page_zone(page),
1495                 (s->flags & SLAB_RECLAIM_ACCOUNT) ?
1496                 NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
1497                 1 << oo_order(oo));
1498 
1499         inc_slabs_node(s, page_to_nid(page), page->objects);
1500 
1501         return page;
1502 }
1503 
1504 static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node)
1505 {
1506         if (unlikely(flags & GFP_SLAB_BUG_MASK)) {
1507                 pr_emerg("gfp: %u\n", flags & GFP_SLAB_BUG_MASK);
1508                 BUG();
1509         }
1510 
1511         return allocate_slab(s,
1512                 flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
1513 }
1514 
1515 static void __free_slab(struct kmem_cache *s, struct page *page)
1516 {
1517         int order = compound_order(page);
1518         int pages = 1 << order;
1519 
1520         if (s->flags & SLAB_CONSISTENCY_CHECKS) {
1521                 void *p;
1522 
1523                 slab_pad_check(s, page);
1524                 for_each_object(p, s, page_address(page),
1525                                                 page->objects)
1526                         check_object(s, page, p, SLUB_RED_INACTIVE);
1527         }
1528 
1529         kmemcheck_free_shadow(page, compound_order(page));
1530 
1531         mod_zone_page_state(page_zone(page),
1532                 (s->flags & SLAB_RECLAIM_ACCOUNT) ?
1533                 NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE,
1534                 -pages);
1535 
1536         __ClearPageSlabPfmemalloc(page);
1537         __ClearPageSlab(page);
1538 
1539         page_mapcount_reset(page);
1540         if (current->reclaim_state)
1541                 current->reclaim_state->reclaimed_slab += pages;
1542         memcg_uncharge_slab(page, order, s);
1543         __free_pages(page, order);
1544 }
1545 
1546 #define need_reserve_slab_rcu                                           \
1547         (sizeof(((struct page *)NULL)->lru) < sizeof(struct rcu_head))
1548 
1549 static void rcu_free_slab(struct rcu_head *h)
1550 {
1551         struct page *page;
1552 
1553         if (need_reserve_slab_rcu)
1554                 page = virt_to_head_page(h);
1555         else
1556                 page = container_of((struct list_head *)h, struct page, lru);
1557 
1558         __free_slab(page->slab_cache, page);
1559 }
1560 
1561 static void free_slab(struct kmem_cache *s, struct page *page)
1562 {
1563         if (unlikely(s->flags & SLAB_DESTROY_BY_RCU)) {
1564                 struct rcu_head *head;
1565 
1566                 if (need_reserve_slab_rcu) {
1567                         int order = compound_order(page);
1568                         int offset = (PAGE_SIZE << order) - s->reserved;
1569 
1570                         VM_BUG_ON(s->reserved != sizeof(*head));
1571                         head = page_address(page) + offset;
1572                 } else {
1573                         head = &page->rcu_head;
1574                 }
1575 
1576                 call_rcu(head, rcu_free_slab);
1577         } else
1578                 __free_slab(s, page);
1579 }
1580 
1581 static void discard_slab(struct kmem_cache *s, struct page *page)
1582 {
1583         dec_slabs_node(s, page_to_nid(page), page->objects);
1584         free_slab(s, page);
1585 }
1586 
1587 /*
1588  * Management of partially allocated slabs.
1589  */
1590 static inline void
1591 __add_partial(struct kmem_cache_node *n, struct page *page, int tail)
1592 {
1593         n->nr_partial++;
1594         if (tail == DEACTIVATE_TO_TAIL)
1595                 list_add_tail(&page->lru, &n->partial);
1596         else
1597                 list_add(&page->lru, &n->partial);
1598 }
1599 
1600 static inline void add_partial(struct kmem_cache_node *n,
1601                                 struct page *page, int tail)
1602 {
1603         lockdep_assert_held(&n->list_lock);
1604         __add_partial(n, page, tail);
1605 }
1606 
1607 static inline void remove_partial(struct kmem_cache_node *n,
1608                                         struct page *page)
1609 {
1610         lockdep_assert_held(&n->list_lock);
1611         list_del(&page->lru);
1612         n->nr_partial--;
1613 }
1614 
1615 /*
1616  * Remove slab from the partial list, freeze it and
1617  * return the pointer to the freelist.
1618  *
1619  * Returns a list of objects or NULL if it fails.
1620  */
1621 static inline void *acquire_slab(struct kmem_cache *s,
1622                 struct kmem_cache_node *n, struct page *page,
1623                 int mode, int *objects)
1624 {
1625         void *freelist;
1626         unsigned long counters;
1627         struct page new;
1628 
1629         lockdep_assert_held(&n->list_lock);
1630 
1631         /*
1632          * Zap the freelist and set the frozen bit.
1633          * The old freelist is the list of objects for the
1634          * per cpu allocation list.
1635          */
1636         freelist = page->freelist;
1637         counters = page->counters;
1638         new.counters = counters;
1639         *objects = new.objects - new.inuse;
1640         if (mode) {
1641                 new.inuse = page->objects;
1642                 new.freelist = NULL;
1643         } else {
1644                 new.freelist = freelist;
1645         }
1646 
1647         VM_BUG_ON(new.frozen);
1648         new.frozen = 1;
1649 
1650         if (!__cmpxchg_double_slab(s, page,
1651                         freelist, counters,
1652                         new.freelist, new.counters,
1653                         "acquire_slab"))
1654                 return NULL;
1655 
1656         remove_partial(n, page);
1657         WARN_ON(!freelist);
1658         return freelist;
1659 }
1660 
1661 static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain);
1662 static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags);
1663 
1664 /*
1665  * Try to allocate a partial slab from a specific node.
1666  */
1667 static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n,
1668                                 struct kmem_cache_cpu *c, gfp_t flags)
1669 {
1670         struct page *page, *page2;
1671         void *object = NULL;
1672         int available = 0;
1673         int objects;
1674 
1675         /*
1676          * Racy check. If we mistakenly see no partial slabs then we
1677          * just allocate an empty slab. If we mistakenly try to get a
1678          * partial slab and there is none available then get_partials()
1679          * will return NULL.
1680          */
1681         if (!n || !n->nr_partial)
1682                 return NULL;
1683 
1684         spin_lock(&n->list_lock);
1685         list_for_each_entry_safe(page, page2, &n->partial, lru) {
1686                 void *t;
1687 
1688                 if (!pfmemalloc_match(page, flags))
1689                         continue;
1690 
1691                 t = acquire_slab(s, n, page, object == NULL, &objects);
1692                 if (!t)
1693                         break;
1694 
1695                 available += objects;
1696                 if (!object) {
1697                         c->page = page;
1698                         stat(s, ALLOC_FROM_PARTIAL);
1699                         object = t;
1700                 } else {
1701                         put_cpu_partial(s, page, 0);
1702                         stat(s, CPU_PARTIAL_NODE);
1703                 }
1704                 if (!kmem_cache_has_cpu_partial(s)
1705                         || available > s->cpu_partial / 2)
1706                         break;
1707 
1708         }
1709         spin_unlock(&n->list_lock);
1710         return object;
1711 }
1712 
1713 /*
1714  * Get a page from somewhere. Search in increasing NUMA distances.
1715  */
1716 static void *get_any_partial(struct kmem_cache *s, gfp_t flags,
1717                 struct kmem_cache_cpu *c)
1718 {
1719 #ifdef CONFIG_NUMA
1720         struct zonelist *zonelist;
1721         struct zoneref *z;
1722         struct zone *zone;
1723         enum zone_type high_zoneidx = gfp_zone(flags);
1724         void *object;
1725         unsigned int cpuset_mems_cookie;
1726 
1727         /*
1728          * The defrag ratio allows a configuration of the tradeoffs between
1729          * inter node defragmentation and node local allocations. A lower
1730          * defrag_ratio increases the tendency to do local allocations
1731          * instead of attempting to obtain partial slabs from other nodes.
1732          *
1733          * If the defrag_ratio is set to 0 then kmalloc() always
1734          * returns node local objects. If the ratio is higher then kmalloc()
1735          * may return off node objects because partial slabs are obtained
1736          * from other nodes and filled up.
1737          *
1738          * If /sys/kernel/slab/xx/defrag_ratio is set to 100 (which makes
1739          * defrag_ratio = 1000) then every (well almost) allocation will
1740          * first attempt to defrag slab caches on other nodes. This means
1741          * scanning over all nodes to look for partial slabs which may be
1742          * expensive if we do it every time we are trying to find a slab
1743          * with available objects.
1744          */
1745         if (!s->remote_node_defrag_ratio ||
1746                         get_cycles() % 1024 > s->remote_node_defrag_ratio)
1747                 return NULL;
1748 
1749         do {
1750                 cpuset_mems_cookie = read_mems_allowed_begin();
1751                 zonelist = node_zonelist(mempolicy_slab_node(), flags);
1752                 for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) {
1753                         struct kmem_cache_node *n;
1754 
1755                         n = get_node(s, zone_to_nid(zone));
1756 
1757                         if (n && cpuset_zone_allowed(zone, flags) &&
1758                                         n->nr_partial > s->min_partial) {
1759                                 object = get_partial_node(s, n, c, flags);
1760                                 if (object) {
1761                                         /*
1762                                          * Don't check read_mems_allowed_retry()
1763                                          * here - if mems_allowed was updated in
1764                                          * parallel, that was a harmless race
1765                                          * between allocation and the cpuset
1766                                          * update
1767                                          */
1768                                         return object;
1769                                 }
1770                         }
1771                 }
1772         } while (read_mems_allowed_retry(cpuset_mems_cookie));
1773 #endif
1774         return NULL;
1775 }
1776 
1777 /*
1778  * Get a partial page, lock it and return it.
1779  */
1780 static void *get_partial(struct kmem_cache *s, gfp_t flags, int node,
1781                 struct kmem_cache_cpu *c)
1782 {
1783         void *object;
1784         int searchnode = node;
1785 
1786         if (node == NUMA_NO_NODE)
1787                 searchnode = numa_mem_id();
1788         else if (!node_present_pages(node))
1789                 searchnode = node_to_mem_node(node);
1790 
1791         object = get_partial_node(s, get_node(s, searchnode), c, flags);
1792         if (object || node != NUMA_NO_NODE)
1793                 return object;
1794 
1795         return get_any_partial(s, flags, c);
1796 }
1797 
1798 #ifdef CONFIG_PREEMPT
1799 /*
1800  * Calculate the next globally unique transaction for disambiguiation
1801  * during cmpxchg. The transactions start with the cpu number and are then
1802  * incremented by CONFIG_NR_CPUS.
1803  */
1804 #define TID_STEP  roundup_pow_of_two(CONFIG_NR_CPUS)
1805 #else
1806 /*
1807  * No preemption supported therefore also no need to check for
1808  * different cpus.
1809  */
1810 #define TID_STEP 1
1811 #endif
1812 
1813 static inline unsigned long next_tid(unsigned long tid)
1814 {
1815         return tid + TID_STEP;
1816 }
1817 
1818 static inline unsigned int tid_to_cpu(unsigned long tid)
1819 {
1820         return tid % TID_STEP;
1821 }
1822 
1823 static inline unsigned long tid_to_event(unsigned long tid)
1824 {
1825         return tid / TID_STEP;
1826 }
1827 
1828 static inline unsigned int init_tid(int cpu)
1829 {
1830         return cpu;
1831 }
1832 
1833 static inline void note_cmpxchg_failure(const char *n,
1834                 const struct kmem_cache *s, unsigned long tid)
1835 {
1836 #ifdef SLUB_DEBUG_CMPXCHG
1837         unsigned long actual_tid = __this_cpu_read(s->cpu_slab->tid);
1838 
1839         pr_info("%s %s: cmpxchg redo ", n, s->name);
1840 
1841 #ifdef CONFIG_PREEMPT
1842         if (tid_to_cpu(tid) != tid_to_cpu(actual_tid))
1843                 pr_warn("due to cpu change %d -> %d\n",
1844                         tid_to_cpu(tid), tid_to_cpu(actual_tid));
1845         else
1846 #endif
1847         if (tid_to_event(tid) != tid_to_event(actual_tid))
1848                 pr_warn("due to cpu running other code. Event %ld->%ld\n",
1849                         tid_to_event(tid), tid_to_event(actual_tid));
1850         else
1851                 pr_warn("for unknown reason: actual=%lx was=%lx target=%lx\n",
1852                         actual_tid, tid, next_tid(tid));
1853 #endif
1854         stat(s, CMPXCHG_DOUBLE_CPU_FAIL);
1855 }
1856 
1857 static void init_kmem_cache_cpus(struct kmem_cache *s)
1858 {
1859         int cpu;
1860 
1861         for_each_possible_cpu(cpu)
1862                 per_cpu_ptr(s->cpu_slab, cpu)->tid = init_tid(cpu);
1863 }
1864 
1865 /*
1866  * Remove the cpu slab
1867  */
1868 static void deactivate_slab(struct kmem_cache *s, struct page *page,
1869                                 void *freelist)
1870 {
1871         enum slab_modes { M_NONE, M_PARTIAL, M_FULL, M_FREE };
1872         struct kmem_cache_node *n = get_node(s, page_to_nid(page));
1873         int lock = 0;
1874         enum slab_modes l = M_NONE, m = M_NONE;
1875         void *nextfree;
1876         int tail = DEACTIVATE_TO_HEAD;
1877         struct page new;
1878         struct page old;
1879 
1880         if (page->freelist) {
1881                 stat(s, DEACTIVATE_REMOTE_FREES);
1882                 tail = DEACTIVATE_TO_TAIL;
1883         }
1884 
1885         /*
1886          * Stage one: Free all available per cpu objects back
1887          * to the page freelist while it is still frozen. Leave the
1888          * last one.
1889          *
1890          * There is no need to take the list->lock because the page
1891          * is still frozen.
1892          */
1893         while (freelist && (nextfree = get_freepointer(s, freelist))) {
1894                 void *prior;
1895                 unsigned long counters;
1896 
1897                 do {
1898                         prior = page->freelist;
1899                         counters = page->counters;
1900                         set_freepointer(s, freelist, prior);
1901                         new.counters = counters;
1902                         new.inuse--;
1903                         VM_BUG_ON(!new.frozen);
1904 
1905                 } while (!__cmpxchg_double_slab(s, page,
1906                         prior, counters,
1907                         freelist, new.counters,
1908                         "drain percpu freelist"));
1909 
1910                 freelist = nextfree;
1911         }
1912 
1913         /*
1914          * Stage two: Ensure that the page is unfrozen while the
1915          * list presence reflects the actual number of objects
1916          * during unfreeze.
1917          *
1918          * We setup the list membership and then perform a cmpxchg
1919          * with the count. If there is a mismatch then the page
1920          * is not unfrozen but the page is on the wrong list.
1921          *
1922          * Then we restart the process which may have to remove
1923          * the page from the list that we just put it on again
1924          * because the number of objects in the slab may have
1925          * changed.
1926          */
1927 redo:
1928 
1929         old.freelist = page->freelist;
1930         old.counters = page->counters;
1931         VM_BUG_ON(!old.frozen);
1932 
1933         /* Determine target state of the slab */
1934         new.counters = old.counters;
1935         if (freelist) {
1936                 new.inuse--;
1937                 set_freepointer(s, freelist, old.freelist);
1938                 new.freelist = freelist;
1939         } else
1940                 new.freelist = old.freelist;
1941 
1942         new.frozen = 0;
1943 
1944         if (!new.inuse && n->nr_partial >= s->min_partial)
1945                 m = M_FREE;
1946         else if (new.freelist) {
1947                 m = M_PARTIAL;
1948                 if (!lock) {
1949                         lock = 1;
1950                         /*
1951                          * Taking the spinlock removes the possiblity
1952                          * that acquire_slab() will see a slab page that
1953                          * is frozen
1954                          */
1955                         spin_lock(&n->list_lock);
1956                 }
1957         } else {
1958                 m = M_FULL;
1959                 if (kmem_cache_debug(s) && !lock) {
1960                         lock = 1;
1961                         /*
1962                          * This also ensures that the scanning of full
1963                          * slabs from diagnostic functions will not see
1964                          * any frozen slabs.
1965                          */
1966                         spin_lock(&n->list_lock);
1967                 }
1968         }
1969 
1970         if (l != m) {
1971 
1972                 if (l == M_PARTIAL)
1973 
1974                         remove_partial(n, page);
1975 
1976                 else if (l == M_FULL)
1977 
1978                         remove_full(s, n, page);
1979 
1980                 if (m == M_PARTIAL) {
1981 
1982                         add_partial(n, page, tail);
1983                         stat(s, tail);
1984 
1985                 } else if (m == M_FULL) {
1986 
1987                         stat(s, DEACTIVATE_FULL);
1988                         add_full(s, n, page);
1989 
1990                 }
1991         }
1992 
1993         l = m;
1994         if (!__cmpxchg_double_slab(s, page,
1995                                 old.freelist, old.counters,
1996                                 new.freelist, new.counters,
1997                                 "unfreezing slab"))
1998                 goto redo;
1999 
2000         if (lock)
2001                 spin_unlock(&n->list_lock);
2002 
2003         if (m == M_FREE) {
2004                 stat(s, DEACTIVATE_EMPTY);
2005                 discard_slab(s, page);
2006                 stat(s, FREE_SLAB);
2007         }
2008 }
2009 
2010 /*
2011  * Unfreeze all the cpu partial slabs.
2012  *
2013  * This function must be called with interrupts disabled
2014  * for the cpu using c (or some other guarantee must be there
2015  * to guarantee no concurrent accesses).
2016  */
2017 static void unfreeze_partials(struct kmem_cache *s,
2018                 struct kmem_cache_cpu *c)
2019 {
2020 #ifdef CONFIG_SLUB_CPU_PARTIAL
2021         struct kmem_cache_node *n = NULL, *n2 = NULL;
2022         struct page *page, *discard_page = NULL;
2023 
2024         while ((page = c->partial)) {
2025                 struct page new;
2026                 struct page old;
2027 
2028                 c->partial = page->next;
2029 
2030                 n2 = get_node(s, page_to_nid(page));
2031                 if (n != n2) {
2032                         if (n)
2033                                 spin_unlock(&n->list_lock);
2034 
2035                         n = n2;
2036                         spin_lock(&n->list_lock);
2037                 }
2038 
2039                 do {
2040 
2041                         old.freelist = page->freelist;
2042                         old.counters = page->counters;
2043                         VM_BUG_ON(!old.frozen);
2044 
2045                         new.counters = old.counters;
2046                         new.freelist = old.freelist;
2047 
2048                         new.frozen = 0;
2049 
2050                 } while (!__cmpxchg_double_slab(s, page,
2051                                 old.freelist, old.counters,
2052                                 new.freelist, new.counters,
2053                                 "unfreezing slab"));
2054 
2055                 if (unlikely(!new.inuse && n->nr_partial >= s->min_partial)) {
2056                         page->next = discard_page;
2057                         discard_page = page;
2058                 } else {
2059                         add_partial(n, page, DEACTIVATE_TO_TAIL);
2060                         stat(s, FREE_ADD_PARTIAL);
2061                 }
2062         }
2063 
2064         if (n)
2065                 spin_unlock(&n->list_lock);
2066 
2067         while (discard_page) {
2068                 page = discard_page;
2069                 discard_page = discard_page->next;
2070 
2071                 stat(s, DEACTIVATE_EMPTY);
2072                 discard_slab(s, page);
2073                 stat(s, FREE_SLAB);
2074         }
2075 #endif
2076 }
2077 
2078 /*
2079  * Put a page that was just frozen (in __slab_free) into a partial page
2080  * slot if available. This is done without interrupts disabled and without
2081  * preemption disabled. The cmpxchg is racy and may put the partial page
2082  * onto a random cpus partial slot.
2083  *
2084  * If we did not find a slot then simply move all the partials to the
2085  * per node partial list.
2086  */
2087 static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain)
2088 {
2089 #ifdef CONFIG_SLUB_CPU_PARTIAL
2090         struct page *oldpage;
2091         int pages;
2092         int pobjects;
2093 
2094         preempt_disable();
2095         do {
2096                 pages = 0;
2097                 pobjects = 0;
2098                 oldpage = this_cpu_read(s->cpu_slab->partial);
2099 
2100                 if (oldpage) {
2101                         pobjects = oldpage->pobjects;
2102                         pages = oldpage->pages;
2103                         if (drain && pobjects > s->cpu_partial) {
2104                                 unsigned long flags;
2105                                 /*
2106                                  * partial array is full. Move the existing
2107                                  * set to the per node partial list.
2108                                  */
2109                                 local_irq_save(flags);
2110                                 unfreeze_partials(s, this_cpu_ptr(s->cpu_slab));
2111                                 local_irq_restore(flags);
2112                                 oldpage = NULL;
2113                                 pobjects = 0;
2114                                 pages = 0;
2115                                 stat(s, CPU_PARTIAL_DRAIN);
2116                         }
2117                 }
2118 
2119                 pages++;
2120                 pobjects += page->objects - page->inuse;
2121 
2122                 page->pages = pages;
2123                 page->pobjects = pobjects;
2124                 page->next = oldpage;
2125 
2126         } while (this_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page)
2127                                                                 != oldpage);
2128         if (unlikely(!s->cpu_partial)) {
2129                 unsigned long flags;
2130 
2131                 local_irq_save(flags);
2132                 unfreeze_partials(s, this_cpu_ptr(s->cpu_slab));
2133                 local_irq_restore(flags);
2134         }
2135         preempt_enable();
2136 #endif
2137 }
2138 
2139 static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c)
2140 {
2141         stat(s, CPUSLAB_FLUSH);
2142         deactivate_slab(s, c->page, c->freelist);
2143 
2144         c->tid = next_tid(c->tid);
2145         c->page = NULL;
2146         c->freelist = NULL;
2147 }
2148 
2149 /*
2150  * Flush cpu slab.
2151  *
2152  * Called from IPI handler with interrupts disabled.
2153  */
2154 static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu)
2155 {
2156         struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
2157 
2158         if (likely(c)) {
2159                 if (c->page)
2160                         flush_slab(s, c);
2161 
2162                 unfreeze_partials(s, c);
2163         }
2164 }
2165 
2166 static void flush_cpu_slab(void *d)
2167 {
2168         struct kmem_cache *s = d;
2169 
2170         __flush_cpu_slab(s, smp_processor_id());
2171 }
2172 
2173 static bool has_cpu_slab(int cpu, void *info)
2174 {
2175         struct kmem_cache *s = info;
2176         struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu);
2177 
2178         return c->page || c->partial;
2179 }
2180 
2181 static void flush_all(struct kmem_cache *s)
2182 {
2183         on_each_cpu_cond(has_cpu_slab, flush_cpu_slab, s, 1, GFP_ATOMIC);
2184 }
2185 
2186 /*
2187  * Check if the objects in a per cpu structure fit numa
2188  * locality expectations.
2189  */
2190 static inline int node_match(struct page *page, int node)
2191 {
2192 #ifdef CONFIG_NUMA
2193         if (!page || (node != NUMA_NO_NODE && page_to_nid(page) != node))
2194                 return 0;
2195 #endif
2196         return 1;
2197 }
2198 
2199 #ifdef CONFIG_SLUB_DEBUG
2200 static int count_free(struct page *page)
2201 {
2202         return page->objects - page->inuse;
2203 }
2204 
2205 static inline unsigned long node_nr_objs(struct kmem_cache_node *n)
2206 {
2207         return atomic_long_read(&n->total_objects);
2208 }
2209 #endif /* CONFIG_SLUB_DEBUG */
2210 
2211 #if defined(CONFIG_SLUB_DEBUG) || defined(CONFIG_SYSFS)
2212 static unsigned long count_partial(struct kmem_cache_node *n,
2213                                         int (*get_count)(struct page *))
2214 {
2215         unsigned long flags;
2216         unsigned long x = 0;
2217         struct page *page;
2218 
2219         spin_lock_irqsave(&n->list_lock, flags);
2220         list_for_each_entry(page, &n->partial, lru)
2221                 x += get_count(page);
2222         spin_unlock_irqrestore(&n->list_lock, flags);
2223         return x;
2224 }
2225 #endif /* CONFIG_SLUB_DEBUG || CONFIG_SYSFS */
2226 
2227 static noinline void
2228 slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid)
2229 {
2230 #ifdef CONFIG_SLUB_DEBUG
2231         static DEFINE_RATELIMIT_STATE(slub_oom_rs, DEFAULT_RATELIMIT_INTERVAL,
2232                                       DEFAULT_RATELIMIT_BURST);
2233         int node;
2234         struct kmem_cache_node *n;
2235 
2236         if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slub_oom_rs))
2237                 return;
2238 
2239         pr_warn("SLUB: Unable to allocate memory on node %d, gfp=%#x(%pGg)\n",
2240                 nid, gfpflags, &gfpflags);
2241         pr_warn("  cache: %s, object size: %d, buffer size: %d, default order: %d, min order: %d\n",
2242                 s->name, s->object_size, s->size, oo_order(s->oo),
2243                 oo_order(s->min));
2244 
2245         if (oo_order(s->min) > get_order(s->object_size))
2246                 pr_warn("  %s debugging increased min order, use slub_debug=O to disable.\n",
2247                         s->name);
2248 
2249         for_each_kmem_cache_node(s, node, n) {
2250                 unsigned long nr_slabs;
2251                 unsigned long nr_objs;
2252                 unsigned long nr_free;
2253 
2254                 nr_free  = count_partial(n, count_free);
2255                 nr_slabs = node_nr_slabs(n);
2256                 nr_objs  = node_nr_objs(n);
2257 
2258                 pr_warn("  node %d: slabs: %ld, objs: %ld, free: %ld\n",
2259                         node, nr_slabs, nr_objs, nr_free);
2260         }
2261 #endif
2262 }
2263 
2264 static inline void *new_slab_objects(struct kmem_cache *s, gfp_t flags,
2265                         int node, struct kmem_cache_cpu **pc)
2266 {
2267         void *freelist;
2268         struct kmem_cache_cpu *c = *pc;
2269         struct page *page;
2270 
2271         freelist = get_partial(s, flags, node, c);
2272 
2273         if (freelist)
2274                 return freelist;
2275 
2276         page = new_slab(s, flags, node);
2277         if (page) {
2278                 c = raw_cpu_ptr(s->cpu_slab);
2279                 if (c->page)
2280                         flush_slab(s, c);
2281 
2282                 /*
2283                  * No other reference to the page yet so we can
2284                  * muck around with it freely without cmpxchg
2285                  */
2286                 freelist = page->freelist;
2287                 page->freelist = NULL;
2288 
2289                 stat(s, ALLOC_SLAB);
2290                 c->page = page;
2291                 *pc = c;
2292         } else
2293                 freelist = NULL;
2294 
2295         return freelist;
2296 }
2297 
2298 static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags)
2299 {
2300         if (unlikely(PageSlabPfmemalloc(page)))
2301                 return gfp_pfmemalloc_allowed(gfpflags);
2302 
2303         return true;
2304 }
2305 
2306 /*
2307  * Check the page->freelist of a page and either transfer the freelist to the
2308  * per cpu freelist or deactivate the page.
2309  *
2310  * The page is still frozen if the return value is not NULL.
2311  *
2312  * If this function returns NULL then the page has been unfrozen.
2313  *
2314  * This function must be called with interrupt disabled.
2315  */
2316 static inline void *get_freelist(struct kmem_cache *s, struct page *page)
2317 {
2318         struct page new;
2319         unsigned long counters;
2320         void *freelist;
2321 
2322         do {
2323                 freelist = page->freelist;
2324                 counters = page->counters;
2325 
2326                 new.counters = counters;
2327                 VM_BUG_ON(!new.frozen);
2328 
2329                 new.inuse = page->objects;
2330                 new.frozen = freelist != NULL;
2331 
2332         } while (!__cmpxchg_double_slab(s, page,
2333                 freelist, counters,
2334                 NULL, new.counters,
2335                 "get_freelist"));
2336 
2337         return freelist;
2338 }
2339 
2340 /*
2341  * Slow path. The lockless freelist is empty or we need to perform
2342  * debugging duties.
2343  *
2344  * Processing is still very fast if new objects have been freed to the
2345  * regular freelist. In that case we simply take over the regular freelist
2346  * as the lockless freelist and zap the regular freelist.
2347  *
2348  * If that is not working then we fall back to the partial lists. We take the
2349  * first element of the freelist as the object to allocate now and move the
2350  * rest of the freelist to the lockless freelist.
2351  *
2352  * And if we were unable to get a new slab from the partial slab lists then
2353  * we need to allocate a new slab. This is the slowest path since it involves
2354  * a call to the page allocator and the setup of a new slab.
2355  *
2356  * Version of __slab_alloc to use when we know that interrupts are
2357  * already disabled (which is the case for bulk allocation).
2358  */
2359 static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
2360                           unsigned long addr, struct kmem_cache_cpu *c)
2361 {
2362         void *freelist;
2363         struct page *page;
2364 
2365         page = c->page;
2366         if (!page)
2367                 goto new_slab;
2368 redo:
2369 
2370         if (unlikely(!node_match(page, node))) {
2371                 int searchnode = node;
2372 
2373                 if (node != NUMA_NO_NODE && !node_present_pages(node))
2374                         searchnode = node_to_mem_node(node);
2375 
2376                 if (unlikely(!node_match(page, searchnode))) {
2377                         stat(s, ALLOC_NODE_MISMATCH);
2378                         deactivate_slab(s, page, c->freelist);
2379                         c->page = NULL;
2380                         c->freelist = NULL;
2381                         goto new_slab;
2382                 }
2383         }
2384 
2385         /*
2386          * By rights, we should be searching for a slab page that was
2387          * PFMEMALLOC but right now, we are losing the pfmemalloc
2388          * information when the page leaves the per-cpu allocator
2389          */
2390         if (unlikely(!pfmemalloc_match(page, gfpflags))) {
2391                 deactivate_slab(s, page, c->freelist);
2392                 c->page = NULL;
2393                 c->freelist = NULL;
2394                 goto new_slab;
2395         }
2396 
2397         /* must check again c->freelist in case of cpu migration or IRQ */
2398         freelist = c->freelist;
2399         if (freelist)
2400                 goto load_freelist;
2401 
2402         freelist = get_freelist(s, page);
2403 
2404         if (!freelist) {
2405                 c->page = NULL;
2406                 stat(s, DEACTIVATE_BYPASS);
2407                 goto new_slab;
2408         }
2409 
2410         stat(s, ALLOC_REFILL);
2411 
2412 load_freelist:
2413         /*
2414          * freelist is pointing to the list of objects to be used.
2415          * page is pointing to the page from which the objects are obtained.
2416          * That page must be frozen for per cpu allocations to work.
2417          */
2418         VM_BUG_ON(!c->page->frozen);
2419         c->freelist = get_freepointer(s, freelist);
2420         c->tid = next_tid(c->tid);
2421         return freelist;
2422 
2423 new_slab:
2424 
2425         if (c->partial) {
2426                 page = c->page = c->partial;
2427                 c->partial = page->next;
2428                 stat(s, CPU_PARTIAL_ALLOC);
2429                 c->freelist = NULL;
2430                 goto redo;
2431         }
2432 
2433         freelist = new_slab_objects(s, gfpflags, node, &c);
2434 
2435         if (unlikely(!freelist)) {
2436                 slab_out_of_memory(s, gfpflags, node);
2437                 return NULL;
2438         }
2439 
2440         page = c->page;
2441         if (likely(!kmem_cache_debug(s) && pfmemalloc_match(page, gfpflags)))
2442                 goto load_freelist;
2443 
2444         /* Only entered in the debug case */
2445         if (kmem_cache_debug(s) &&
2446                         !alloc_debug_processing(s, page, freelist, addr))
2447                 goto new_slab;  /* Slab failed checks. Next slab needed */
2448 
2449         deactivate_slab(s, page, get_freepointer(s, freelist));
2450         c->page = NULL;
2451         c->freelist = NULL;
2452         return freelist;
2453 }
2454 
2455 /*
2456  * Another one that disabled interrupt and compensates for possible
2457  * cpu changes by refetching the per cpu area pointer.
2458  */
2459 static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node,
2460                           unsigned long addr, struct kmem_cache_cpu *c)
2461 {
2462         void *p;
2463         unsigned long flags;
2464 
2465         local_irq_save(flags);
2466 #ifdef CONFIG_PREEMPT
2467         /*
2468          * We may have been preempted and rescheduled on a different
2469          * cpu before disabling interrupts. Need to reload cpu area
2470          * pointer.
2471          */
2472         c = this_cpu_ptr(s->cpu_slab);
2473 #endif
2474 
2475         p = ___slab_alloc(s, gfpflags, node, addr, c);
2476         local_irq_restore(flags);
2477         return p;
2478 }
2479 
2480 /*
2481  * Inlined fastpath so that allocation functions (kmalloc, kmem_cache_alloc)
2482  * have the fastpath folded into their functions. So no function call
2483  * overhead for requests that can be satisfied on the fastpath.
2484  *
2485  * The fastpath works by first checking if the lockless freelist can be used.
2486  * If not then __slab_alloc is called for slow processing.
2487  *
2488  * Otherwise we can simply pick the next object from the lockless free list.
2489  */
2490 static __always_inline void *slab_alloc_node(struct kmem_cache *s,
2491                 gfp_t gfpflags, int node, unsigned long addr)
2492 {
2493         void *object;
2494         struct kmem_cache_cpu *c;
2495         struct page *page;
2496         unsigned long tid;
2497 
2498         s = slab_pre_alloc_hook(s, gfpflags);
2499         if (!s)
2500                 return NULL;
2501 redo:
2502         /*
2503          * Must read kmem_cache cpu data via this cpu ptr. Preemption is
2504          * enabled. We may switch back and forth between cpus while
2505          * reading from one cpu area. That does not matter as long
2506          * as we end up on the original cpu again when doing the cmpxchg.
2507          *
2508          * We should guarantee that tid and kmem_cache are retrieved on
2509          * the same cpu. It could be different if CONFIG_PREEMPT so we need
2510          * to check if it is matched or not.
2511          */
2512         do {
2513                 tid = this_cpu_read(s->cpu_slab->tid);
2514                 c = raw_cpu_ptr(s->cpu_slab);
2515         } while (IS_ENABLED(CONFIG_PREEMPT) &&
2516                  unlikely(tid != READ_ONCE(c->tid)));
2517 
2518         /*
2519          * Irqless object alloc/free algorithm used here depends on sequence
2520          * of fetching cpu_slab's data. tid should be fetched before anything
2521          * on c to guarantee that object and page associated with previous tid
2522          * won't be used with current tid. If we fetch tid first, object and
2523          * page could be one associated with next tid and our alloc/free
2524          * request will be failed. In this case, we will retry. So, no problem.
2525          */
2526         barrier();
2527 
2528         /*
2529          * The transaction ids are globally unique per cpu and per operation on
2530          * a per cpu queue. Thus they can be guarantee that the cmpxchg_double
2531          * occurs on the right processor and that there was no operation on the
2532          * linked list in between.
2533          */
2534 
2535         object = c->freelist;
2536         page = c->page;
2537         if (unlikely(!object || !node_match(page, node))) {
2538                 object = __slab_alloc(s, gfpflags, node, addr, c);
2539                 stat(s, ALLOC_SLOWPATH);
2540         } else {
2541                 void *next_object = get_freepointer_safe(s, object);
2542 
2543                 /*
2544                  * The cmpxchg will only match if there was no additional
2545                  * operation and if we are on the right processor.
2546                  *
2547                  * The cmpxchg does the following atomically (without lock
2548                  * semantics!)
2549                  * 1. Relocate first pointer to the current per cpu area.
2550                  * 2. Verify that tid and freelist have not been changed
2551                  * 3. If they were not changed replace tid and freelist
2552                  *
2553                  * Since this is without lock semantics the protection is only
2554                  * against code executing on this cpu *not* from access by
2555                  * other cpus.
2556                  */
2557                 if (unlikely(!this_cpu_cmpxchg_double(
2558                                 s->cpu_slab->freelist, s->cpu_slab->tid,
2559                                 object, tid,
2560                                 next_object, next_tid(tid)))) {
2561 
2562                         note_cmpxchg_failure("slab_alloc", s, tid);
2563                         goto redo;
2564                 }
2565                 prefetch_freepointer(s, next_object);
2566                 stat(s, ALLOC_FASTPATH);
2567         }
2568 
2569         if (unlikely(gfpflags & __GFP_ZERO) && object)
2570                 memset(object, 0, s->object_size);
2571 
2572         slab_post_alloc_hook(s, gfpflags, 1, &object);
2573 
2574         return object;
2575 }
2576 
2577 static __always_inline void *slab_alloc(struct kmem_cache *s,
2578                 gfp_t gfpflags, unsigned long addr)
2579 {
2580         return slab_alloc_node(s, gfpflags, NUMA_NO_NODE, addr);
2581 }
2582 
2583 void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags)
2584 {
2585         void *ret = slab_alloc(s, gfpflags, _RET_IP_);
2586 
2587         trace_kmem_cache_alloc(_RET_IP_, ret, s->object_size,
2588                                 s->size, gfpflags);
2589 
2590         return ret;
2591 }
2592 EXPORT_SYMBOL(kmem_cache_alloc);
2593 
2594 #ifdef CONFIG_TRACING
2595 void *kmem_cache_alloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size)
2596 {
2597         void *ret = slab_alloc(s, gfpflags, _RET_IP_);
2598         trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags);
2599         kasan_kmalloc(s, ret, size, gfpflags);
2600         return ret;
2601 }
2602 EXPORT_SYMBOL(kmem_cache_alloc_trace);
2603 #endif
2604 
2605 #ifdef CONFIG_NUMA
2606 void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node)
2607 {
2608         void *ret = slab_alloc_node(s, gfpflags, node, _RET_IP_);
2609 
2610         trace_kmem_cache_alloc_node(_RET_IP_, ret,
2611                                     s->object_size, s->size, gfpflags, node);
2612 
2613         return ret;
2614 }
2615 EXPORT_SYMBOL(kmem_cache_alloc_node);
2616 
2617 #ifdef CONFIG_TRACING
2618 void *kmem_cache_alloc_node_trace(struct kmem_cache *s,
2619                                     gfp_t gfpflags,
2620                                     int node, size_t size)
2621 {
2622         void *ret = slab_alloc_node(s, gfpflags, node, _RET_IP_);
2623 
2624         trace_kmalloc_node(_RET_IP_, ret,
2625                            size, s->size, gfpflags, node);
2626 
2627         kasan_kmalloc(s, ret, size, gfpflags);
2628         return ret;
2629 }
2630 EXPORT_SYMBOL(kmem_cache_alloc_node_trace);
2631 #endif
2632 #endif
2633 
2634 /*
2635  * Slow path handling. This may still be called frequently since objects
2636  * have a longer lifetime than the cpu slabs in most processing loads.
2637  *
2638  * So we still attempt to reduce cache line usage. Just take the slab
2639  * lock and free the item. If there is no additional partial page
2640  * handling required then we can return immediately.
2641  */
2642 static void __slab_free(struct kmem_cache *s, struct page *page,
2643                         void *head, void *tail, int cnt,
2644                         unsigned long addr)
2645 
2646 {
2647         void *prior;
2648         int was_frozen;
2649         struct page new;
2650         unsigned long counters;
2651         struct kmem_cache_node *n = NULL;
2652         unsigned long uninitialized_var(flags);
2653 
2654         stat(s, FREE_SLOWPATH);
2655 
2656         if (kmem_cache_debug(s) &&
2657             !free_debug_processing(s, page, head, tail, cnt, addr))
2658                 return;
2659 
2660         do {
2661                 if (unlikely(n)) {
2662                         spin_unlock_irqrestore(&n->list_lock, flags);
2663                         n = NULL;
2664                 }
2665                 prior = page->freelist;
2666                 counters = page->counters;
2667                 set_freepointer(s, tail, prior);
2668                 new.counters = counters;
2669                 was_frozen = new.frozen;
2670                 new.inuse -= cnt;
2671                 if ((!new.inuse || !prior) && !was_frozen) {
2672 
2673                         if (kmem_cache_has_cpu_partial(s) && !prior) {
2674 
2675                                 /*
2676                                  * Slab was on no list before and will be
2677                                  * partially empty
2678                                  * We can defer the list move and instead
2679                                  * freeze it.
2680                                  */
2681                                 new.frozen = 1;
2682 
2683                         } else { /* Needs to be taken off a list */
2684 
2685                                 n = get_node(s, page_to_nid(page));
2686                                 /*
2687                                  * Speculatively acquire the list_lock.
2688                                  * If the cmpxchg does not succeed then we may
2689                                  * drop the list_lock without any processing.
2690                                  *
2691                                  * Otherwise the list_lock will synchronize with
2692                                  * other processors updating the list of slabs.
2693                                  */
2694                                 spin_lock_irqsave(&n->list_lock, flags);
2695 
2696                         }
2697                 }
2698 
2699         } while (!cmpxchg_double_slab(s, page,
2700                 prior, counters,
2701                 head, new.counters,
2702                 "__slab_free"));
2703 
2704         if (likely(!n)) {
2705 
2706                 /*
2707                  * If we just froze the page then put it onto the
2708                  * per cpu partial list.
2709                  */
2710                 if (new.frozen && !was_frozen) {
2711                         put_cpu_partial(s, page, 1);
2712                         stat(s, CPU_PARTIAL_FREE);
2713                 }
2714                 /*
2715                  * The list lock was not taken therefore no list
2716                  * activity can be necessary.
2717                  */
2718                 if (was_frozen)
2719                         stat(s, FREE_FROZEN);
2720                 return;
2721         }
2722 
2723         if (unlikely(!new.inuse && n->nr_partial >= s->min_partial))
2724                 goto slab_empty;
2725 
2726         /*
2727          * Objects left in the slab. If it was not on the partial list before
2728          * then add it.
2729          */
2730         if (!kmem_cache_has_cpu_partial(s) && unlikely(!prior)) {
2731                 if (kmem_cache_debug(s))
2732                         remove_full(s, n, page);
2733                 add_partial(n, page, DEACTIVATE_TO_TAIL);
2734                 stat(s, FREE_ADD_PARTIAL);
2735         }
2736         spin_unlock_irqrestore(&n->list_lock, flags);
2737         return;
2738 
2739 slab_empty:
2740         if (prior) {
2741                 /*
2742                  * Slab on the partial list.
2743                  */
2744                 remove_partial(n, page);
2745                 stat(s, FREE_REMOVE_PARTIAL);
2746         } else {
2747                 /* Slab must be on the full list */
2748                 remove_full(s, n, page);
2749         }
2750 
2751         spin_unlock_irqrestore(&n->list_lock, flags);
2752         stat(s, FREE_SLAB);
2753         discard_slab(s, page);
2754 }
2755 
2756 /*
2757  * Fastpath with forced inlining to produce a kfree and kmem_cache_free that
2758  * can perform fastpath freeing without additional function calls.
2759  *
2760  * The fastpath is only possible if we are freeing to the current cpu slab
2761  * of this processor. This typically the case if we have just allocated
2762  * the item before.
2763  *
2764  * If fastpath is not possible then fall back to __slab_free where we deal
2765  * with all sorts of special processing.
2766  *
2767  * Bulk free of a freelist with several objects (all pointing to the
2768  * same page) possible by specifying head and tail ptr, plus objects
2769  * count (cnt). Bulk free indicated by tail pointer being set.
2770  */
2771 static __always_inline void slab_free(struct kmem_cache *s, struct page *page,
2772                                       void *head, void *tail, int cnt,
2773                                       unsigned long addr)
2774 {
2775         void *tail_obj = tail ? : head;
2776         struct kmem_cache_cpu *c;
2777         unsigned long tid;
2778 
2779         slab_free_freelist_hook(s, head, tail);
2780 
2781 redo:
2782         /*
2783          * Determine the currently cpus per cpu slab.
2784          * The cpu may change afterward. However that does not matter since
2785          * data is retrieved via this pointer. If we are on the same cpu
2786          * during the cmpxchg then the free will succeed.
2787          */
2788         do {
2789                 tid = this_cpu_read(s->cpu_slab->tid);
2790                 c = raw_cpu_ptr(s->cpu_slab);
2791         } while (IS_ENABLED(CONFIG_PREEMPT) &&
2792                  unlikely(tid != READ_ONCE(c->tid)));
2793 
2794         /* Same with comment on barrier() in slab_alloc_node() */
2795         barrier();
2796 
2797         if (likely(page == c->page)) {
2798                 set_freepointer(s, tail_obj, c->freelist);
2799 
2800                 if (unlikely(!this_cpu_cmpxchg_double(
2801                                 s->cpu_slab->freelist, s->cpu_slab->tid,
2802                                 c->freelist, tid,
2803                                 head, next_tid(tid)))) {
2804 
2805                         note_cmpxchg_failure("slab_free", s, tid);
2806                         goto redo;
2807                 }
2808                 stat(s, FREE_FASTPATH);
2809         } else
2810                 __slab_free(s, page, head, tail_obj, cnt, addr);
2811 
2812 }
2813 
2814 void kmem_cache_free(struct kmem_cache *s, void *x)
2815 {
2816         s = cache_from_obj(s, x);
2817         if (!s)
2818                 return;
2819         slab_free(s, virt_to_head_page(x), x, NULL, 1, _RET_IP_);
2820         trace_kmem_cache_free(_RET_IP_, x);
2821 }
2822 EXPORT_SYMBOL(kmem_cache_free);
2823 
2824 struct detached_freelist {
2825         struct page *page;
2826         void *tail;
2827         void *freelist;
2828         int cnt;
2829         struct kmem_cache *s;
2830 };
2831 
2832 /*
2833  * This function progressively scans the array with free objects (with
2834  * a limited look ahead) and extract objects belonging to the same
2835  * page.  It builds a detached freelist directly within the given
2836  * page/objects.  This can happen without any need for
2837  * synchronization, because the objects are owned by running process.
2838  * The freelist is build up as a single linked list in the objects.
2839  * The idea is, that this detached freelist can then be bulk
2840  * transferred to the real freelist(s), but only requiring a single
2841  * synchronization primitive.  Look ahead in the array is limited due
2842  * to performance reasons.
2843  */
2844 static inline
2845 int build_detached_freelist(struct kmem_cache *s, size_t size,
2846                             void **p, struct detached_freelist *df)
2847 {
2848         size_t first_skipped_index = 0;
2849         int lookahead = 3;
2850         void *object;
2851         struct page *page;
2852 
2853         /* Always re-init detached_freelist */
2854         df->page = NULL;
2855 
2856         do {
2857                 object = p[--size];
2858                 /* Do we need !ZERO_OR_NULL_PTR(object) here? (for kfree) */
2859         } while (!object && size);
2860 
2861         if (!object)
2862                 return 0;
2863 
2864         page = virt_to_head_page(object);
2865         if (!s) {
2866                 /* Handle kalloc'ed objects */
2867                 if (unlikely(!PageSlab(page))) {
2868                         BUG_ON(!PageCompound(page));
2869                         kfree_hook(object);
2870                         __free_kmem_pages(page, compound_order(page));
2871                         p[size] = NULL; /* mark object processed */
2872                         return size;
2873                 }
2874                 /* Derive kmem_cache from object */
2875                 df->s = page->slab_cache;
2876         } else {
2877                 df->s = cache_from_obj(s, object); /* Support for memcg */
2878         }
2879 
2880         /* Start new detached freelist */
2881         df->page = page;
2882         set_freepointer(df->s, object, NULL);
2883         df->tail = object;
2884         df->freelist = object;
2885         p[size] = NULL; /* mark object processed */
2886         df->cnt = 1;
2887 
2888         while (size) {
2889                 object = p[--size];
2890                 if (!object)
2891                         continue; /* Skip processed objects */
2892 
2893                 /* df->page is always set at this point */
2894                 if (df->page == virt_to_head_page(object)) {
2895                         /* Opportunity build freelist */
2896                         set_freepointer(df->s, object, df->freelist);
2897                         df->freelist = object;
2898                         df->cnt++;
2899                         p[size] = NULL; /* mark object processed */
2900 
2901                         continue;
2902                 }
2903 
2904                 /* Limit look ahead search */
2905                 if (!--lookahead)
2906                         break;
2907 
2908                 if (!first_skipped_index)
2909                         first_skipped_index = size + 1;
2910         }
2911 
2912         return first_skipped_index;
2913 }
2914 
2915 /* Note that interrupts must be enabled when calling this function. */
2916 void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p)
2917 {
2918         if (WARN_ON(!size))
2919                 return;
2920 
2921         do {
2922                 struct detached_freelist df;
2923 
2924                 size = build_detached_freelist(s, size, p, &df);
2925                 if (unlikely(!df.page))
2926                         continue;
2927 
2928                 slab_free(df.s, df.page, df.freelist, df.tail, df.cnt,_RET_IP_);
2929         } while (likely(size));
2930 }
2931 EXPORT_SYMBOL(kmem_cache_free_bulk);
2932 
2933 /* Note that interrupts must be enabled when calling this function. */
2934 int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size,
2935                           void **p)
2936 {
2937         struct kmem_cache_cpu *c;
2938         int i;
2939 
2940         /* memcg and kmem_cache debug support */
2941         s = slab_pre_alloc_hook(s, flags);
2942         if (unlikely(!s))
2943                 return false;
2944         /*
2945          * Drain objects in the per cpu slab, while disabling local
2946          * IRQs, which protects against PREEMPT and interrupts
2947          * handlers invoking normal fastpath.
2948          */
2949         local_irq_disable();
2950         c = this_cpu_ptr(s->cpu_slab);
2951 
2952         for (i = 0; i < size; i++) {
2953                 void *object = c->freelist;
2954 
2955                 if (unlikely(!object)) {
2956                         /*
2957                          * Invoking slow path likely have side-effect
2958                          * of re-populating per CPU c->freelist
2959                          */
2960                         p[i] = ___slab_alloc(s, flags, NUMA_NO_NODE,
2961                                             _RET_IP_, c);
2962                         if (unlikely(!p[i]))
2963                                 goto error;
2964 
2965                         c = this_cpu_ptr(s->cpu_slab);
2966                         continue; /* goto for-loop */
2967                 }
2968                 c->freelist = get_freepointer(s, object);
2969                 p[i] = object;
2970         }
2971         c->tid = next_tid(c->tid);
2972         local_irq_enable();
2973 
2974         /* Clear memory outside IRQ disabled fastpath loop */
2975         if (unlikely(flags & __GFP_ZERO)) {
2976                 int j;
2977 
2978                 for (j = 0; j < i; j++)
2979                         memset(p[j], 0, s->object_size);
2980         }
2981 
2982         /* memcg and kmem_cache debug support */
2983         slab_post_alloc_hook(s, flags, size, p);
2984         return i;
2985 error:
2986         local_irq_enable();
2987         slab_post_alloc_hook(s, flags, i, p);
2988         __kmem_cache_free_bulk(s, i, p);
2989         return 0;
2990 }
2991 EXPORT_SYMBOL(kmem_cache_alloc_bulk);
2992 
2993 
2994 /*
2995  * Object placement in a slab is made very easy because we always start at
2996  * offset 0. If we tune the size of the object to the alignment then we can
2997  * get the required alignment by putting one properly sized object after
2998  * another.
2999  *
3000  * Notice that the allocation order determines the sizes of the per cpu
3001  * caches. Each processor has always one slab available for allocations.
3002  * Increasing the allocation order reduces the number of times that slabs
3003  * must be moved on and off the partial lists and is therefore a factor in
3004  * locking overhead.
3005  */
3006 
3007 /*
3008  * Mininum / Maximum order of slab pages. This influences locking overhead
3009  * and slab fragmentation. A higher order reduces the number of partial slabs
3010  * and increases the number of allocations possible without having to
3011  * take the list_lock.
3012  */
3013 static int slub_min_order;
3014 static int slub_max_order = PAGE_ALLOC_COSTLY_ORDER;
3015 static int slub_min_objects;
3016 
3017 /*
3018  * Calculate the order of allocation given an slab object size.
3019  *
3020  * The order of allocation has significant impact on performance and other
3021  * system components. Generally order 0 allocations should be preferred since
3022  * order 0 does not cause fragmentation in the page allocator. Larger objects
3023  * be problematic to put into order 0 slabs because there may be too much
3024  * unused space left. We go to a higher order if more than 1/16th of the slab
3025  * would be wasted.
3026  *
3027  * In order to reach satisfactory performance we must ensure that a minimum
3028  * number of objects is in one slab. Otherwise we may generate too much
3029  * activity on the partial lists which requires taking the list_lock. This is
3030  * less a concern for large slabs though which are rarely used.
3031  *
3032  * slub_max_order specifies the order where we begin to stop considering the
3033  * number of objects in a slab as critical. If we reach slub_max_order then
3034  * we try to keep the page order as low as possible. So we accept more waste
3035  * of space in favor of a small page order.
3036  *
3037  * Higher order allocations also allow the placement of more objects in a
3038  * slab and thereby reduce object handling overhead. If the user has
3039  * requested a higher mininum order then we start with that one instead of
3040  * the smallest order which will fit the object.
3041  */
3042 static inline int slab_order(int size, int min_objects,
3043                                 int max_order, int fract_leftover, int reserved)
3044 {
3045         int order;
3046         int rem;
3047         int min_order = slub_min_order;
3048 
3049         if (order_objects(min_order, size, reserved) > MAX_OBJS_PER_PAGE)
3050                 return get_order(size * MAX_OBJS_PER_PAGE) - 1;
3051 
3052         for (order = max(min_order, get_order(min_objects * size + reserved));
3053                         order <= max_order; order++) {
3054 
3055                 unsigned long slab_size = PAGE_SIZE << order;
3056 
3057                 rem = (slab_size - reserved) % size;
3058 
3059                 if (rem <= slab_size / fract_leftover)
3060                         break;
3061         }
3062 
3063         return order;
3064 }
3065 
3066 static inline int calculate_order(int size, int reserved)
3067 {
3068         int order;
3069         int min_objects;
3070         int fraction;
3071         int max_objects;
3072 
3073         /*
3074          * Attempt to find best configuration for a slab. This
3075          * works by first attempting to generate a layout with
3076          * the best configuration and backing off gradually.
3077          *
3078          * First we increase the acceptable waste in a slab. Then
3079          * we reduce the minimum objects required in a slab.
3080          */
3081         min_objects = slub_min_objects;
3082         if (!min_objects)
3083                 min_objects = 4 * (fls(nr_cpu_ids) + 1);
3084         max_objects = order_objects(slub_max_order, size, reserved);
3085         min_objects = min(min_objects, max_objects);
3086 
3087         while (min_objects > 1) {
3088                 fraction = 16;
3089                 while (fraction >= 4) {
3090                         order = slab_order(size, min_objects,
3091                                         slub_max_order, fraction, reserved);
3092                         if (order <= slub_max_order)
3093                                 return order;
3094                         fraction /= 2;
3095                 }
3096                 min_objects--;
3097         }
3098 
3099         /*
3100          * We were unable to place multiple objects in a slab. Now
3101          * lets see if we can place a single object there.
3102          */
3103         order = slab_order(size, 1, slub_max_order, 1, reserved);
3104         if (order <= slub_max_order)
3105                 return order;
3106 
3107         /*
3108          * Doh this slab cannot be placed using slub_max_order.
3109          */
3110         order = slab_order(size, 1, MAX_ORDER, 1, reserved);
3111         if (order < MAX_ORDER)
3112                 return order;
3113         return -ENOSYS;
3114 }
3115 
3116 static void
3117 init_kmem_cache_node(struct kmem_cache_node *n)
3118 {
3119         n->nr_partial = 0;
3120         spin_lock_init(&n->list_lock);
3121         INIT_LIST_HEAD(&n->partial);
3122 #ifdef CONFIG_SLUB_DEBUG
3123         atomic_long_set(&n->nr_slabs, 0);
3124         atomic_long_set(&n->total_objects, 0);
3125         INIT_LIST_HEAD(&n->full);
3126 #endif
3127 }
3128 
3129 static inline int alloc_kmem_cache_cpus(struct kmem_cache *s)
3130 {
3131         BUILD_BUG_ON(PERCPU_DYNAMIC_EARLY_SIZE <
3132                         KMALLOC_SHIFT_HIGH * sizeof(struct kmem_cache_cpu));
3133 
3134         /*
3135          * Must align to double word boundary for the double cmpxchg
3136          * instructions to work; see __pcpu_double_call_return_bool().
3137          */
3138         s->cpu_slab = __alloc_percpu(sizeof(struct kmem_cache_cpu),
3139                                      2 * sizeof(void *));
3140 
3141         if (!s->cpu_slab)
3142                 return 0;
3143 
3144         init_kmem_cache_cpus(s);
3145 
3146         return 1;
3147 }
3148 
3149 static struct kmem_cache *kmem_cache_node;
3150 
3151 /*
3152  * No kmalloc_node yet so do it by hand. We know that this is the first
3153  * slab on the node for this slabcache. There are no concurrent accesses
3154  * possible.
3155  *
3156  * Note that this function only works on the kmem_cache_node
3157  * when allocating for the kmem_cache_node. This is used for bootstrapping
3158  * memory on a fresh node that has no slab structures yet.
3159  */
3160 static void early_kmem_cache_node_alloc(int node)
3161 {
3162         struct page *page;
3163         struct kmem_cache_node *n;
3164 
3165         BUG_ON(kmem_cache_node->size < sizeof(struct kmem_cache_node));
3166 
3167         page = new_slab(kmem_cache_node, GFP_NOWAIT, node);
3168 
3169         BUG_ON(!page);
3170         if (page_to_nid(page) != node) {
3171                 pr_err("SLUB: Unable to allocate memory from node %d\n", node);
3172                 pr_err("SLUB: Allocating a useless per node structure in order to be able to continue\n");
3173         }
3174 
3175         n = page->freelist;
3176         BUG_ON(!n);
3177         page->freelist = get_freepointer(kmem_cache_node, n);
3178         page->inuse = 1;
3179         page->frozen = 0;
3180         kmem_cache_node->node[node] = n;
3181 #ifdef CONFIG_SLUB_DEBUG
3182         init_object(kmem_cache_node, n, SLUB_RED_ACTIVE);
3183         init_tracking(kmem_cache_node, n);
3184 #endif
3185         kasan_kmalloc(kmem_cache_node, n, sizeof(struct kmem_cache_node),
3186                       GFP_KERNEL);
3187         init_kmem_cache_node(n);
3188         inc_slabs_node(kmem_cache_node, node, page->objects);
3189 
3190         /*
3191          * No locks need to be taken here as it has just been
3192          * initialized and there is no concurrent access.
3193          */
3194         __add_partial(n, page, DEACTIVATE_TO_HEAD);
3195 }
3196 
3197 static void free_kmem_cache_nodes(struct kmem_cache *s)
3198 {
3199         int node;
3200         struct kmem_cache_node *n;
3201 
3202         for_each_kmem_cache_node(s, node, n) {
3203                 kmem_cache_free(kmem_cache_node, n);
3204                 s->node[node] = NULL;
3205         }
3206 }
3207 
3208 void __kmem_cache_release(struct kmem_cache *s)
3209 {
3210         free_percpu(s->cpu_slab);
3211         free_kmem_cache_nodes(s);
3212 }
3213 
3214 static int init_kmem_cache_nodes(struct kmem_cache *s)
3215 {
3216         int node;
3217 
3218         for_each_node_state(node, N_NORMAL_MEMORY) {
3219                 struct kmem_cache_node *n;
3220 
3221                 if (slab_state == DOWN) {
3222                         early_kmem_cache_node_alloc(node);
3223                         continue;
3224                 }
3225                 n = kmem_cache_alloc_node(kmem_cache_node,
3226                                                 GFP_KERNEL, node);
3227 
3228                 if (!n) {
3229                         free_kmem_cache_nodes(s);
3230                         return 0;
3231                 }
3232 
3233                 s->node[node] = n;
3234                 init_kmem_cache_node(n);
3235         }
3236         return 1;
3237 }
3238 
3239 static void set_min_partial(struct kmem_cache *s, unsigned long min)
3240 {
3241         if (min < MIN_PARTIAL)
3242                 min = MIN_PARTIAL;
3243         else if (min > MAX_PARTIAL)
3244                 min = MAX_PARTIAL;
3245         s->min_partial = min;
3246 }
3247 
3248 /*
3249  * calculate_sizes() determines the order and the distribution of data within
3250  * a slab object.
3251  */
3252 static int calculate_sizes(struct kmem_cache *s, int forced_order)
3253 {
3254         unsigned long flags = s->flags;
3255         unsigned long size = s->object_size;
3256         int order;
3257 
3258         /*
3259          * Round up object size to the next word boundary. We can only
3260          * place the free pointer at word boundaries and this determines
3261          * the possible location of the free pointer.
3262          */
3263         size = ALIGN(size, sizeof(void *));
3264 
3265 #ifdef CONFIG_SLUB_DEBUG
3266         /*
3267          * Determine if we can poison the object itself. If the user of
3268          * the slab may touch the object after free or before allocation
3269          * then we should never poison the object itself.
3270          */
3271         if ((flags & SLAB_POISON) && !(flags & SLAB_DESTROY_BY_RCU) &&
3272                         !s->ctor)
3273                 s->flags |= __OBJECT_POISON;
3274         else
3275                 s->flags &= ~__OBJECT_POISON;
3276 
3277 
3278         /*
3279          * If we are Redzoning then check if there is some space between the
3280          * end of the object and the free pointer. If not then add an
3281          * additional word to have some bytes to store Redzone information.
3282          */
3283         if ((flags & SLAB_RED_ZONE) && size == s->object_size)
3284                 size += sizeof(void *);
3285 #endif
3286 
3287         /*
3288          * With that we have determined the number of bytes in actual use
3289          * by the object. This is the potential offset to the free pointer.
3290          */
3291         s->inuse = size;
3292 
3293         if (((flags & (SLAB_DESTROY_BY_RCU | SLAB_POISON)) ||
3294                 s->ctor)) {
3295                 /*
3296                  * Relocate free pointer after the object if it is not
3297                  * permitted to overwrite the first word of the object on
3298                  * kmem_cache_free.
3299                  *
3300                  * This is the case if we do RCU, have a constructor or
3301                  * destructor or are poisoning the objects.
3302                  */
3303                 s->offset = size;
3304                 size += sizeof(void *);
3305         }
3306 
3307 #ifdef CONFIG_SLUB_DEBUG
3308         if (flags & SLAB_STORE_USER)
3309                 /*
3310                  * Need to store information about allocs and frees after
3311                  * the object.
3312                  */
3313                 size += 2 * sizeof(struct track);
3314 
3315         if (flags & SLAB_RED_ZONE) {
3316                 /*
3317                  * Add some empty padding so that we can catch
3318                  * overwrites from earlier objects rather than let
3319                  * tracking information or the free pointer be
3320                  * corrupted if a user writes before the start
3321                  * of the object.
3322                  */
3323                 size += sizeof(void *);
3324 
3325                 s->red_left_pad = sizeof(void *);
3326                 s->red_left_pad = ALIGN(s->red_left_pad, s->align);
3327                 size += s->red_left_pad;
3328         }
3329 #endif
3330 
3331         /*
3332          * SLUB stores one object immediately after another beginning from
3333          * offset 0. In order to align the objects we have to simply size
3334          * each object to conform to the alignment.
3335          */
3336         size = ALIGN(size, s->align);
3337         s->size = size;
3338         if (forced_order >= 0)
3339                 order = forced_order;
3340         else
3341                 order = calculate_order(size, s->reserved);
3342 
3343         if (order < 0)
3344                 return 0;
3345 
3346         s->allocflags = 0;
3347         if (order)
3348                 s->allocflags |= __GFP_COMP;
3349 
3350         if (s->flags & SLAB_CACHE_DMA)
3351                 s->allocflags |= GFP_DMA;
3352 
3353         if (s->flags & SLAB_RECLAIM_ACCOUNT)
3354                 s->allocflags |= __GFP_RECLAIMABLE;
3355 
3356         /*
3357          * Determine the number of objects per slab
3358          */
3359         s->oo = oo_make(order, size, s->reserved);
3360         s->min = oo_make(get_order(size), size, s->reserved);
3361         if (oo_objects(s->oo) > oo_objects(s->max))
3362                 s->max = s->oo;
3363 
3364         return !!oo_objects(s->oo);
3365 }
3366 
3367 static int kmem_cache_open(struct kmem_cache *s, unsigned long flags)
3368 {
3369         s->flags = kmem_cache_flags(s->size, flags, s->name, s->ctor);
3370         s->reserved = 0;
3371 
3372         if (need_reserve_slab_rcu && (s->flags & SLAB_DESTROY_BY_RCU))
3373                 s->reserved = sizeof(struct rcu_head);
3374 
3375         if (!calculate_sizes(s, -1))
3376                 goto error;
3377         if (disable_higher_order_debug) {
3378                 /*
3379                  * Disable debugging flags that store metadata if the min slab
3380                  * order increased.
3381                  */
3382                 if (get_order(s->size) > get_order(s->object_size)) {
3383                         s->flags &= ~DEBUG_METADATA_FLAGS;
3384                         s->offset = 0;
3385                         if (!calculate_sizes(s, -1))
3386                                 goto error;
3387                 }
3388         }
3389 
3390 #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \
3391     defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE)
3392         if (system_has_cmpxchg_double() && (s->flags & SLAB_NO_CMPXCHG) == 0)
3393                 /* Enable fast mode */
3394                 s->flags |= __CMPXCHG_DOUBLE;
3395 #endif
3396 
3397         /*
3398          * The larger the object size is, the more pages we want on the partial
3399          * list to avoid pounding the page allocator excessively.
3400          */
3401         set_min_partial(s, ilog2(s->size) / 2);
3402 
3403         /*
3404          * cpu_partial determined the maximum number of objects kept in the
3405          * per cpu partial lists of a processor.
3406          *
3407          * Per cpu partial lists mainly contain slabs that just have one
3408          * object freed. If they are used for allocation then they can be
3409          * filled up again with minimal effort. The slab will never hit the
3410          * per node partial lists and therefore no locking will be required.
3411          *
3412          * This setting also determines
3413          *
3414          * A) The number of objects from per cpu partial slabs dumped to the
3415          *    per node list when we reach the limit.
3416          * B) The number of objects in cpu partial slabs to extract from the
3417          *    per node list when we run out of per cpu objects. We only fetch
3418          *    50% to keep some capacity around for frees.
3419          */
3420         if (!kmem_cache_has_cpu_partial(s))
3421                 s->cpu_partial = 0;
3422         else if (s->size >= PAGE_SIZE)
3423                 s->cpu_partial = 2;
3424         else if (s->size >= 1024)
3425                 s->cpu_partial = 6;
3426         else if (s->size >= 256)
3427                 s->cpu_partial = 13;
3428         else
3429                 s->cpu_partial = 30;
3430 
3431 #ifdef CONFIG_NUMA
3432         s->remote_node_defrag_ratio = 1000;
3433 #endif
3434         if (!init_kmem_cache_nodes(s))
3435                 goto error;
3436 
3437         if (alloc_kmem_cache_cpus(s))
3438                 return 0;
3439 
3440         free_kmem_cache_nodes(s);
3441 error:
3442         if (flags & SLAB_PANIC)
3443                 panic("Cannot create slab %s size=%lu realsize=%u order=%u offset=%u flags=%lx\n",
3444                       s->name, (unsigned long)s->size, s->size,
3445                       oo_order(s->oo), s->offset, flags);
3446         return -EINVAL;
3447 }
3448 
3449 static void list_slab_objects(struct kmem_cache *s, struct page *page,
3450                                                         const char *text)
3451 {
3452 #ifdef CONFIG_SLUB_DEBUG
3453         void *addr = page_address(page);
3454         void *p;
3455         unsigned long *map = kzalloc(BITS_TO_LONGS(page->objects) *
3456                                      sizeof(long), GFP_ATOMIC);
3457         if (!map)
3458                 return;
3459         slab_err(s, page, text, s->name);
3460         slab_lock(page);
3461 
3462         get_map(s, page, map);
3463         for_each_object(p, s, addr, page->objects) {
3464 
3465                 if (!test_bit(slab_index(p, s, addr), map)) {
3466                         pr_err("INFO: Object 0x%p @offset=%tu\n", p, p - addr);
3467                         print_tracking(s, p);
3468                 }
3469         }
3470         slab_unlock(page);
3471         kfree(map);
3472 #endif
3473 }
3474 
3475 /*
3476  * Attempt to free all partial slabs on a node.
3477  * This is called from __kmem_cache_shutdown(). We must take list_lock
3478  * because sysfs file might still access partial list after the shutdowning.
3479  */
3480 static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n)
3481 {
3482         struct page *page, *h;
3483 
3484         BUG_ON(irqs_disabled());
3485         spin_lock_irq(&n->list_lock);
3486         list_for_each_entry_safe(page, h, &n->partial, lru) {
3487                 if (!page->inuse) {
3488                         remove_partial(n, page);
3489                         discard_slab(s, page);
3490                 } else {
3491                         list_slab_objects(s, page,
3492                         "Objects remaining in %s on __kmem_cache_shutdown()");
3493                 }
3494         }
3495         spin_unlock_irq(&n->list_lock);
3496 }
3497 
3498 /*
3499  * Release all resources used by a slab cache.
3500  */
3501 int __kmem_cache_shutdown(struct kmem_cache *s)
3502 {
3503         int node;
3504         struct kmem_cache_node *n;
3505 
3506         flush_all(s);
3507         /* Attempt to free all objects */
3508         for_each_kmem_cache_node(s, node, n) {
3509                 free_partial(s, n);
3510                 if (n->nr_partial || slabs_node(s, node))
3511                         return 1;
3512         }
3513         return 0;
3514 }
3515 
3516 /********************************************************************
3517  *              Kmalloc subsystem
3518  *******************************************************************/
3519 
3520 static int __init setup_slub_min_order(char *str)
3521 {
3522         get_option(&str, &slub_min_order);
3523 
3524         return 1;
3525 }
3526 
3527 __setup("slub_min_order=", setup_slub_min_order);
3528 
3529 static int __init setup_slub_max_order(char *str)
3530 {
3531         get_option(&str, &slub_max_order);
3532         slub_max_order = min(slub_max_order, MAX_ORDER - 1);
3533 
3534         return 1;
3535 }
3536 
3537 __setup("slub_max_order=", setup_slub_max_order);
3538 
3539 static int __init setup_slub_min_objects(char *str)
3540 {
3541         get_option(&str, &slub_min_objects);
3542 
3543         return 1;
3544 }
3545 
3546 __setup("slub_min_objects=", setup_slub_min_objects);
3547 
3548 void *__kmalloc(size_t size, gfp_t flags)
3549 {
3550         struct kmem_cache *s;
3551         void *ret;
3552 
3553         if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
3554                 return kmalloc_large(size, flags);
3555 
3556         s = kmalloc_slab(size, flags);
3557 
3558         if (unlikely(ZERO_OR_NULL_PTR(s)))
3559                 return s;
3560 
3561         ret = slab_alloc(s, flags, _RET_IP_);
3562 
3563         trace_kmalloc(_RET_IP_, ret, size, s->size, flags);
3564 
3565         kasan_kmalloc(s, ret, size, flags);
3566 
3567         return ret;
3568 }
3569 EXPORT_SYMBOL(__kmalloc);
3570 
3571 #ifdef CONFIG_NUMA
3572 static void *kmalloc_large_node(size_t size, gfp_t flags, int node)
3573 {
3574         struct page *page;
3575         void *ptr = NULL;
3576 
3577         flags |= __GFP_COMP | __GFP_NOTRACK;
3578         page = alloc_kmem_pages_node(node, flags, get_order(size));
3579         if (page)
3580                 ptr = page_address(page);
3581 
3582         kmalloc_large_node_hook(ptr, size, flags);
3583         return ptr;
3584 }
3585 
3586 void *__kmalloc_node(size_t size, gfp_t flags, int node)
3587 {
3588         struct kmem_cache *s;
3589         void *ret;
3590 
3591         if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
3592                 ret = kmalloc_large_node(size, flags, node);
3593 
3594                 trace_kmalloc_node(_RET_IP_, ret,
3595                                    size, PAGE_SIZE << get_order(size),
3596                                    flags, node);
3597 
3598                 return ret;
3599         }
3600 
3601         s = kmalloc_slab(size, flags);
3602 
3603         if (unlikely(ZERO_OR_NULL_PTR(s)))
3604                 return s;
3605 
3606         ret = slab_alloc_node(s, flags, node, _RET_IP_);
3607 
3608         trace_kmalloc_node(_RET_IP_, ret, size, s->size, flags, node);
3609 
3610         kasan_kmalloc(s, ret, size, flags);
3611 
3612         return ret;
3613 }
3614 EXPORT_SYMBOL(__kmalloc_node);
3615 #endif
3616 
3617 static size_t __ksize(const void *object)
3618 {
3619         struct page *page;
3620 
3621         if (unlikely(object == ZERO_SIZE_PTR))
3622                 return 0;
3623 
3624         page = virt_to_head_page(object);
3625 
3626         if (unlikely(!PageSlab(page))) {
3627                 WARN_ON(!PageCompound(page));
3628                 return PAGE_SIZE << compound_order(page);
3629         }
3630 
3631         return slab_ksize(page->slab_cache);
3632 }
3633 
3634 size_t ksize(const void *object)
3635 {
3636         size_t size = __ksize(object);
3637         /* We assume that ksize callers could use whole allocated area,
3638            so we need unpoison this area. */
3639         kasan_krealloc(object, size, GFP_NOWAIT);
3640         return size;
3641 }
3642 EXPORT_SYMBOL(ksize);
3643 
3644 void kfree(const void *x)
3645 {
3646         struct page *page;
3647         void *object = (void *)x;
3648 
3649         trace_kfree(_RET_IP_, x);
3650 
3651         if (unlikely(ZERO_OR_NULL_PTR(x)))
3652                 return;
3653 
3654         page = virt_to_head_page(x);
3655         if (unlikely(!PageSlab(page))) {
3656                 BUG_ON(!PageCompound(page));
3657                 kfree_hook(x);
3658                 __free_kmem_pages(page, compound_order(page));
3659                 return;
3660         }
3661         slab_free(page->slab_cache, page, object, NULL, 1, _RET_IP_);
3662 }
3663 EXPORT_SYMBOL(kfree);
3664 
3665 #define SHRINK_PROMOTE_MAX 32
3666 
3667 /*
3668  * kmem_cache_shrink discards empty slabs and promotes the slabs filled
3669  * up most to the head of the partial lists. New allocations will then
3670  * fill those up and thus they can be removed from the partial lists.
3671  *
3672  * The slabs with the least items are placed last. This results in them
3673  * being allocated from last increasing the chance that the last objects
3674  * are freed in them.
3675  */
3676 int __kmem_cache_shrink(struct kmem_cache *s, bool deactivate)
3677 {
3678         int node;
3679         int i;
3680         struct kmem_cache_node *n;
3681         struct page *page;
3682         struct page *t;
3683         struct list_head discard;
3684         struct list_head promote[SHRINK_PROMOTE_MAX];
3685         unsigned long flags;
3686         int ret = 0;
3687 
3688         if (deactivate) {
3689                 /*
3690                  * Disable empty slabs caching. Used to avoid pinning offline
3691                  * memory cgroups by kmem pages that can be freed.
3692                  */
3693                 s->cpu_partial = 0;
3694                 s->min_partial = 0;
3695 
3696                 /*
3697                  * s->cpu_partial is checked locklessly (see put_cpu_partial),
3698                  * so we have to make sure the change is visible.
3699                  */
3700                 kick_all_cpus_sync();
3701         }
3702 
3703         flush_all(s);
3704         for_each_kmem_cache_node(s, node, n) {
3705                 INIT_LIST_HEAD(&discard);
3706                 for (i = 0; i < SHRINK_PROMOTE_MAX; i++)
3707                         INIT_LIST_HEAD(promote + i);
3708 
3709                 spin_lock_irqsave(&n->list_lock, flags);
3710 
3711                 /*
3712                  * Build lists of slabs to discard or promote.
3713                  *
3714                  * Note that concurrent frees may occur while we hold the
3715                  * list_lock. page->inuse here is the upper limit.
3716                  */
3717                 list_for_each_entry_safe(page, t, &n->partial, lru) {
3718                         int free = page->objects - page->inuse;
3719 
3720                         /* Do not reread page->inuse */
3721                         barrier();
3722 
3723                         /* We do not keep full slabs on the list */
3724                         BUG_ON(free <= 0);
3725 
3726                         if (free == page->objects) {
3727                                 list_move(&page->lru, &discard);
3728                                 n->nr_partial--;
3729                         } else if (free <= SHRINK_PROMOTE_MAX)
3730                                 list_move(&page->lru, promote + free - 1);
3731                 }
3732 
3733                 /*
3734                  * Promote the slabs filled up most to the head of the
3735                  * partial list.
3736                  */
3737                 for (i = SHRINK_PROMOTE_MAX - 1; i >= 0; i--)
3738                         list_splice(promote + i, &n->partial);
3739 
3740                 spin_unlock_irqrestore(&n->list_lock, flags);
3741 
3742                 /* Release empty slabs */
3743                 list_for_each_entry_safe(page, t, &discard, lru)
3744                         discard_slab(s, page);
3745 
3746                 if (slabs_node(s, node))
3747                         ret = 1;
3748         }
3749 
3750         return ret;
3751 }
3752 
3753 static int slab_mem_going_offline_callback(void *arg)
3754 {
3755         struct kmem_cache *s;
3756 
3757         mutex_lock(&slab_mutex);
3758         list_for_each_entry(s, &slab_caches, list)
3759                 __kmem_cache_shrink(s, false);
3760         mutex_unlock(&slab_mutex);
3761 
3762         return 0;
3763 }
3764 
3765 static void slab_mem_offline_callback(void *arg)
3766 {
3767         struct kmem_cache_node *n;
3768         struct kmem_cache *s;
3769         struct memory_notify *marg = arg;
3770         int offline_node;
3771 
3772         offline_node = marg->status_change_nid_normal;
3773 
3774         /*
3775          * If the node still has available memory. we need kmem_cache_node
3776          * for it yet.
3777          */
3778         if (offline_node < 0)
3779                 return;
3780 
3781         mutex_lock(&slab_mutex);
3782         list_for_each_entry(s, &slab_caches, list) {
3783                 n = get_node(s, offline_node);
3784                 if (n) {
3785                         /*
3786                          * if n->nr_slabs > 0, slabs still exist on the node
3787                          * that is going down. We were unable to free them,
3788                          * and offline_pages() function shouldn't call this
3789                          * callback. So, we must fail.
3790                          */
3791                         BUG_ON(slabs_node(s, offline_node));
3792 
3793                         s->node[offline_node] = NULL;
3794                         kmem_cache_free(kmem_cache_node, n);
3795                 }
3796         }
3797         mutex_unlock(&slab_mutex);
3798 }
3799 
3800 static int slab_mem_going_online_callback(void *arg)
3801 {
3802         struct kmem_cache_node *n;
3803         struct kmem_cache *s;
3804         struct memory_notify *marg = arg;
3805         int nid = marg->status_change_nid_normal;
3806         int ret = 0;
3807 
3808         /*
3809          * If the node's memory is already available, then kmem_cache_node is
3810          * already created. Nothing to do.
3811          */
3812         if (nid < 0)
3813                 return 0;
3814 
3815         /*
3816          * We are bringing a node online. No memory is available yet. We must
3817          * allocate a kmem_cache_node structure in order to bring the node
3818          * online.
3819          */
3820         mutex_lock(&slab_mutex);
3821         list_for_each_entry(s, &slab_caches, list) {
3822                 /*
3823                  * XXX: kmem_cache_alloc_node will fallback to other nodes
3824                  *      since memory is not yet available from the node that
3825                  *      is brought up.
3826                  */
3827                 n = kmem_cache_alloc(kmem_cache_node, GFP_KERNEL);
3828                 if (!n) {
3829                         ret = -ENOMEM;
3830                         goto out;
3831                 }
3832                 init_kmem_cache_node(n);
3833                 s->node[nid] = n;
3834         }
3835 out:
3836         mutex_unlock(&slab_mutex);
3837         return ret;
3838 }
3839 
3840 static int slab_memory_callback(struct notifier_block *self,
3841                                 unsigned long action, void *arg)
3842 {
3843         int ret = 0;
3844 
3845         switch (action) {
3846         case MEM_GOING_ONLINE:
3847                 ret = slab_mem_going_online_callback(arg);
3848                 break;
3849         case MEM_GOING_OFFLINE:
3850                 ret = slab_mem_going_offline_callback(arg);
3851                 break;
3852         case MEM_OFFLINE:
3853         case MEM_CANCEL_ONLINE:
3854                 slab_mem_offline_callback(arg);
3855                 break;
3856         case MEM_ONLINE:
3857         case MEM_CANCEL_OFFLINE:
3858                 break;
3859         }
3860         if (ret)
3861                 ret = notifier_from_errno(ret);
3862         else
3863                 ret = NOTIFY_OK;
3864         return ret;
3865 }
3866 
3867 static struct notifier_block slab_memory_callback_nb = {
3868         .notifier_call = slab_memory_callback,
3869         .priority = SLAB_CALLBACK_PRI,
3870 };
3871 
3872 /********************************************************************
3873  *                      Basic setup of slabs
3874  *******************************************************************/
3875 
3876 /*
3877  * Used for early kmem_cache structures that were allocated using
3878  * the page allocator. Allocate them properly then fix up the pointers
3879  * that may be pointing to the wrong kmem_cache structure.
3880  */
3881 
3882 static struct kmem_cache * __init bootstrap(struct kmem_cache *static_cache)
3883 {
3884         int node;
3885         struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
3886         struct kmem_cache_node *n;
3887 
3888         memcpy(s, static_cache, kmem_cache->object_size);
3889 
3890         /*
3891          * This runs very early, and only the boot processor is supposed to be
3892          * up.  Even if it weren't true, IRQs are not up so we couldn't fire
3893          * IPIs around.
3894          */
3895         __flush_cpu_slab(s, smp_processor_id());
3896         for_each_kmem_cache_node(s, node, n) {
3897                 struct page *p;
3898 
3899                 list_for_each_entry(p, &n->partial, lru)
3900                         p->slab_cache = s;
3901 
3902 #ifdef CONFIG_SLUB_DEBUG
3903                 list_for_each_entry(p, &n->full, lru)
3904                         p->slab_cache = s;
3905 #endif
3906         }
3907         slab_init_memcg_params(s);
3908         list_add(&s->list, &slab_caches);
3909         return s;
3910 }
3911 
3912 void __init kmem_cache_init(void)
3913 {
3914         static __initdata struct kmem_cache boot_kmem_cache,
3915                 boot_kmem_cache_node;
3916 
3917         if (debug_guardpage_minorder())
3918                 slub_max_order = 0;
3919 
3920         kmem_cache_node = &boot_kmem_cache_node;
3921         kmem_cache = &boot_kmem_cache;
3922 
3923         create_boot_cache(kmem_cache_node, "kmem_cache_node",
3924                 sizeof(struct kmem_cache_node), SLAB_HWCACHE_ALIGN);
3925 
3926         register_hotmemory_notifier(&slab_memory_callback_nb);
3927 
3928         /* Able to allocate the per node structures */
3929         slab_state = PARTIAL;
3930 
3931         create_boot_cache(kmem_cache, "kmem_cache",
3932                         offsetof(struct kmem_cache, node) +
3933                                 nr_node_ids * sizeof(struct kmem_cache_node *),
3934                        SLAB_HWCACHE_ALIGN);
3935 
3936         kmem_cache = bootstrap(&boot_kmem_cache);
3937 
3938         /*
3939          * Allocate kmem_cache_node properly from the kmem_cache slab.
3940          * kmem_cache_node is separately allocated so no need to
3941          * update any list pointers.
3942          */
3943         kmem_cache_node = bootstrap(&boot_kmem_cache_node);
3944 
3945         /* Now we can use the kmem_cache to allocate kmalloc slabs */
3946         setup_kmalloc_cache_index_table();
3947         create_kmalloc_caches(0);
3948 
3949 #ifdef CONFIG_SMP
3950         register_cpu_notifier(&slab_notifier);
3951 #endif
3952 
3953         pr_info("SLUB: HWalign=%d, Order=%d-%d, MinObjects=%d, CPUs=%d, Nodes=%d\n",
3954                 cache_line_size(),
3955                 slub_min_order, slub_max_order, slub_min_objects,
3956                 nr_cpu_ids, nr_node_ids);
3957 }
3958 
3959 void __init kmem_cache_init_late(void)
3960 {
3961 }
3962 
3963 struct kmem_cache *
3964 __kmem_cache_alias(const char *name, size_t size, size_t align,
3965                    unsigned long flags, void (*ctor)(void *))
3966 {
3967         struct kmem_cache *s, *c;
3968 
3969         s = find_mergeable(size, align, flags, name, ctor);
3970         if (s) {
3971                 s->refcount++;
3972 
3973                 /*
3974                  * Adjust the object sizes so that we clear
3975                  * the complete object on kzalloc.
3976                  */
3977                 s->object_size = max(s->object_size, (int)size);
3978                 s->inuse = max_t(int, s->inuse, ALIGN(size, sizeof(void *)));
3979 
3980                 for_each_memcg_cache(c, s) {
3981                         c->object_size = s->object_size;
3982                         c->inuse = max_t(int, c->inuse,
3983                                          ALIGN(size, sizeof(void *)));
3984                 }
3985 
3986                 if (sysfs_slab_alias(s, name)) {
3987                         s->refcount--;
3988                         s = NULL;
3989                 }
3990         }
3991 
3992         return s;
3993 }
3994 
3995 int __kmem_cache_create(struct kmem_cache *s, unsigned long flags)
3996 {
3997         int err;
3998 
3999         err = kmem_cache_open(s, flags);
4000         if (err)
4001                 return err;
4002 
4003         /* Mutex is not taken during early boot */
4004         if (slab_state <= UP)
4005                 return 0;
4006 
4007         memcg_propagate_slab_attrs(s);
4008         err = sysfs_slab_add(s);
4009         if (err)
4010                 __kmem_cache_release(s);
4011 
4012         return err;
4013 }
4014 
4015 #ifdef CONFIG_SMP
4016 /*
4017  * Use the cpu notifier to insure that the cpu slabs are flushed when
4018  * necessary.
4019  */
4020 static int slab_cpuup_callback(struct notifier_block *nfb,
4021                 unsigned long action, void *hcpu)
4022 {
4023         long cpu = (long)hcpu;
4024         struct kmem_cache *s;
4025         unsigned long flags;
4026 
4027         switch (action) {
4028         case CPU_UP_CANCELED:
4029         case CPU_UP_CANCELED_FROZEN:
4030         case CPU_DEAD:
4031         case CPU_DEAD_FROZEN:
4032                 mutex_lock(&slab_mutex);
4033                 list_for_each_entry(s, &slab_caches, list) {
4034                         local_irq_save(flags);
4035                         __flush_cpu_slab(s, cpu);
4036                         local_irq_restore(flags);
4037                 }
4038                 mutex_unlock(&slab_mutex);
4039                 break;
4040         default:
4041                 break;
4042         }
4043         return NOTIFY_OK;
4044 }
4045 
4046 static struct notifier_block slab_notifier = {
4047         .notifier_call = slab_cpuup_callback
4048 };
4049 
4050 #endif
4051 
4052 void *__kmalloc_track_caller(size_t size, gfp_t gfpflags, unsigned long caller)
4053 {
4054         struct kmem_cache *s;
4055         void *ret;
4056 
4057         if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
4058                 return kmalloc_large(size, gfpflags);
4059 
4060         s = kmalloc_slab(size, gfpflags);
4061 
4062         if (unlikely(ZERO_OR_NULL_PTR(s)))
4063                 return s;
4064 
4065         ret = slab_alloc(s, gfpflags, caller);
4066 
4067         /* Honor the call site pointer we received. */
4068         trace_kmalloc(caller, ret, size, s->size, gfpflags);
4069 
4070         return ret;
4071 }
4072 
4073 #ifdef CONFIG_NUMA
4074 void *__kmalloc_node_track_caller(size_t size, gfp_t gfpflags,
4075                                         int node, unsigned long caller)
4076 {
4077         struct kmem_cache *s;
4078         void *ret;
4079 
4080         if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
4081                 ret = kmalloc_large_node(size, gfpflags, node);
4082 
4083                 trace_kmalloc_node(caller, ret,
4084                                    size, PAGE_SIZE << get_order(size),
4085                                    gfpflags, node);
4086 
4087                 return ret;
4088         }
4089 
4090         s = kmalloc_slab(size, gfpflags);
4091 
4092         if (unlikely(ZERO_OR_NULL_PTR(s)))
4093                 return s;
4094 
4095         ret = slab_alloc_node(s, gfpflags, node, caller);
4096 
4097         /* Honor the call site pointer we received. */
4098         trace_kmalloc_node(caller, ret, size, s->size, gfpflags, node);
4099 
4100         return ret;
4101 }
4102 #endif
4103 
4104 #ifdef CONFIG_SYSFS
4105 static int count_inuse(struct page *page)
4106 {
4107         return page->inuse;
4108 }
4109 
4110 static int count_total(struct page *page)
4111 {
4112         return page->objects;
4113 }
4114 #endif
4115 
4116 #ifdef CONFIG_SLUB_DEBUG
4117 static int validate_slab(struct kmem_cache *s, struct page *page,
4118                                                 unsigned long *map)
4119 {
4120         void *p;
4121         void *addr = page_address(page);
4122 
4123         if (!check_slab(s, page) ||
4124                         !on_freelist(s, page, NULL))
4125                 return 0;
4126 
4127         /* Now we know that a valid freelist exists */
4128         bitmap_zero(map, page->objects);
4129 
4130         get_map(s, page, map);
4131         for_each_object(p, s, addr, page->objects) {
4132                 if (test_bit(slab_index(p, s, addr), map))
4133                         if (!check_object(s, page, p, SLUB_RED_INACTIVE))
4134                                 return 0;
4135         }
4136 
4137         for_each_object(p, s, addr, page->objects)
4138                 if (!test_bit(slab_index(p, s, addr), map))
4139                         if (!check_object(s, page, p, SLUB_RED_ACTIVE))
4140                                 return 0;
4141         return 1;
4142 }
4143 
4144 static void validate_slab_slab(struct kmem_cache *s, struct page *page,
4145                                                 unsigned long *map)
4146 {
4147         slab_lock(page);
4148         validate_slab(s, page, map);
4149         slab_unlock(page);
4150 }
4151 
4152 static int validate_slab_node(struct kmem_cache *s,
4153                 struct kmem_cache_node *n, unsigned long *map)
4154 {
4155         unsigned long count = 0;
4156         struct page *page;
4157         unsigned long flags;
4158 
4159         spin_lock_irqsave(&n->list_lock, flags);
4160 
4161         list_for_each_entry(page, &n->partial, lru) {
4162                 validate_slab_slab(s, page, map);
4163                 count++;
4164         }
4165         if (count != n->nr_partial)
4166                 pr_err("SLUB %s: %ld partial slabs counted but counter=%ld\n",
4167                        s->name, count, n->nr_partial);
4168 
4169         if (!(s->flags & SLAB_STORE_USER))
4170                 goto out;
4171 
4172         list_for_each_entry(page, &n->full, lru) {
4173                 validate_slab_slab(s, page, map);
4174                 count++;
4175         }
4176         if (count != atomic_long_read(&n->nr_slabs))
4177                 pr_err("SLUB: %s %ld slabs counted but counter=%ld\n",
4178                        s->name, count, atomic_long_read(&n->nr_slabs));
4179 
4180 out:
4181         spin_unlock_irqrestore(&n->list_lock, flags);
4182         return count;
4183 }
4184 
4185 static long validate_slab_cache(struct kmem_cache *s)
4186 {
4187         int node;
4188         unsigned long count = 0;
4189         unsigned long *map = kmalloc(BITS_TO_LONGS(oo_objects(s->max)) *
4190                                 sizeof(unsigned long), GFP_KERNEL);
4191         struct kmem_cache_node *n;
4192 
4193         if (!map)
4194                 return -ENOMEM;
4195 
4196         flush_all(s);
4197         for_each_kmem_cache_node(s, node, n)
4198                 count += validate_slab_node(s, n, map);
4199         kfree(map);
4200         return count;
4201 }
4202 /*
4203  * Generate lists of code addresses where slabcache objects are allocated
4204  * and freed.
4205  */
4206 
4207 struct location {
4208         unsigned long count;
4209         unsigned long addr;
4210         long long sum_time;
4211         long min_time;
4212         long max_time;
4213         long min_pid;
4214         long max_pid;
4215         DECLARE_BITMAP(cpus, NR_CPUS);
4216         nodemask_t nodes;
4217 };
4218 
4219 struct loc_track {
4220         unsigned long max;
4221         unsigned long count;
4222         struct location *loc;
4223 };
4224 
4225 static void free_loc_track(struct loc_track *t)
4226 {
4227         if (t->max)
4228                 free_pages((unsigned long)t->loc,
4229                         get_order(sizeof(struct location) * t->max));
4230 }
4231 
4232 static int alloc_loc_track(struct loc_track *t, unsigned long max, gfp_t flags)
4233 {
4234         struct location *l;
4235         int order;
4236 
4237         order = get_order(sizeof(struct location) * max);
4238 
4239         l = (void *)__get_free_pages(flags, order);
4240         if (!l)
4241                 return 0;
4242 
4243         if (t->count) {
4244                 memcpy(l, t->loc, sizeof(struct location) * t->count);
4245                 free_loc_track(t);
4246         }
4247         t->max = max;
4248         t->loc = l;
4249         return 1;
4250 }
4251 
4252 static int add_location(struct loc_track *t, struct kmem_cache *s,
4253                                 const struct track *track)
4254 {
4255         long start, end, pos;
4256         struct location *l;
4257         unsigned long caddr;
4258         unsigned long age = jiffies - track->when;
4259 
4260         start = -1;
4261         end = t->count;
4262 
4263         for ( ; ; ) {
4264                 pos = start + (end - start + 1) / 2;
4265 
4266                 /*
4267                  * There is nothing at "end". If we end up there
4268                  * we need to add something to before end.
4269                  */
4270                 if (pos == end)
4271                         break;
4272 
4273                 caddr = t->loc[pos].addr;
4274                 if (track->addr == caddr) {
4275 
4276                         l = &t->loc[pos];
4277                         l->count++;
4278                         if (track->when) {
4279                                 l->sum_time += age;
4280                                 if (age < l->min_time)
4281                                         l->min_time = age;
4282                                 if (age > l->max_time)
4283                                         l->max_time = age;
4284 
4285                                 if (track->pid < l->min_pid)
4286                                         l->min_pid = track->pid;
4287                                 if (track->pid > l->max_pid)
4288                                         l->max_pid = track->pid;
4289 
4290                                 cpumask_set_cpu(track->cpu,
4291                                                 to_cpumask(l->cpus));
4292                         }
4293                         node_set(page_to_nid(virt_to_page(track)), l->nodes);
4294                         return 1;
4295                 }
4296 
4297                 if (track->addr < caddr)
4298                         end = pos;
4299                 else
4300                         start = pos;
4301         }
4302 
4303         /*
4304          * Not found. Insert new tracking element.
4305          */
4306         if (t->count >= t->max && !alloc_loc_track(t, 2 * t->max, GFP_ATOMIC))
4307                 return 0;
4308 
4309         l = t->loc + pos;
4310         if (pos < t->count)
4311                 memmove(l + 1, l,
4312                         (t->count - pos) * sizeof(struct location));
4313         t->count++;
4314         l->count = 1;
4315         l->addr = track->addr;
4316         l->sum_time = age;
4317         l->min_time = age;
4318         l->max_time = age;
4319         l->min_pid = track->pid;
4320         l->max_pid = track->pid;
4321         cpumask_clear(to_cpumask(l->cpus));
4322         cpumask_set_cpu(track->cpu, to_cpumask(l->cpus));
4323         nodes_clear(l->nodes);
4324         node_set(page_to_nid(virt_to_page(track)), l->nodes);
4325         return 1;
4326 }
4327 
4328 static void process_slab(struct loc_track *t, struct kmem_cache *s,
4329                 struct page *page, enum track_item alloc,
4330                 unsigned long *map)
4331 {
4332         void *addr = page_address(page);
4333         void *p;
4334 
4335         bitmap_zero(map, page->objects);
4336         get_map(s, page, map);
4337 
4338         for_each_object(p, s, addr, page->objects)
4339                 if (!test_bit(slab_index(p, s, addr), map))
4340                         add_location(t, s, get_track(s, p, alloc));
4341 }
4342 
4343 static int list_locations(struct kmem_cache *s, char *buf,
4344                                         enum track_item alloc)
4345 {
4346         int len = 0;
4347         unsigned long i;
4348         struct loc_track t = { 0, 0, NULL };
4349         int node;
4350         unsigned long *map = kmalloc(BITS_TO_LONGS(oo_objects(s->max)) *
4351                                      sizeof(unsigned long), GFP_KERNEL);
4352         struct kmem_cache_node *n;
4353 
4354         if (!map || !alloc_loc_track(&t, PAGE_SIZE / sizeof(struct location),
4355                                      GFP_TEMPORARY)) {
4356                 kfree(map);
4357                 return sprintf(buf, "Out of memory\n");
4358         }
4359         /* Push back cpu slabs */
4360         flush_all(s);
4361 
4362         for_each_kmem_cache_node(s, node, n) {
4363                 unsigned long flags;
4364                 struct page *page;
4365 
4366                 if (!atomic_long_read(&n->nr_slabs))
4367                         continue;
4368 
4369                 spin_lock_irqsave(&n->list_lock, flags);
4370                 list_for_each_entry(page, &n->partial, lru)
4371                         process_slab(&t, s, page, alloc, map);
4372                 list_for_each_entry(page, &n->full, lru)
4373                         process_slab(&t, s, page, alloc, map);
4374                 spin_unlock_irqrestore(&n->list_lock, flags);
4375         }
4376 
4377         for (i = 0; i < t.count; i++) {
4378                 struct location *l = &t.loc[i];
4379 
4380                 if (len > PAGE_SIZE - KSYM_SYMBOL_LEN - 100)
4381                         break;
4382                 len += sprintf(buf + len, "%7ld ", l->count);
4383 
4384                 if (l->addr)
4385                         len += sprintf(buf + len, "%pS", (void *)l->addr);
4386                 else
4387                         len += sprintf(buf + len, "<not-available>");
4388 
4389                 if (l->sum_time != l->min_time) {
4390                         len += sprintf(buf + len, " age=%ld/%ld/%ld",
4391                                 l->min_time,
4392                                 (long)div_u64(l->sum_time, l->count),
4393                                 l->max_time);
4394                 } else
4395                         len += sprintf(buf + len, " age=%ld",
4396                                 l->min_time);
4397 
4398                 if (l->min_pid != l->max_pid)
4399                         len += sprintf(buf + len, " pid=%ld-%ld",
4400                                 l->min_pid, l->max_pid);
4401                 else
4402                         len += sprintf(buf + len, " pid=%ld",
4403                                 l->min_pid);
4404 
4405                 if (num_online_cpus() > 1 &&
4406                                 !cpumask_empty(to_cpumask(l->cpus)) &&
4407                                 len < PAGE_SIZE - 60)
4408                         len += scnprintf(buf + len, PAGE_SIZE - len - 50,
4409                                          " cpus=%*pbl",
4410                                          cpumask_pr_args(to_cpumask(l->cpus)));
4411 
4412                 if (nr_online_nodes > 1 && !nodes_empty(l->nodes) &&
4413                                 len < PAGE_SIZE - 60)
4414                         len += scnprintf(buf + len, PAGE_SIZE - len - 50,
4415                                          " nodes=%*pbl",
4416                                          nodemask_pr_args(&l->nodes));
4417 
4418                 len += sprintf(buf + len, "\n");
4419         }
4420 
4421         free_loc_track(&t);
4422         kfree(map);
4423         if (!t.count)
4424                 len += sprintf(buf, "No data\n");
4425         return len;
4426 }
4427 #endif
4428 
4429 #ifdef SLUB_RESILIENCY_TEST
4430 static void __init resiliency_test(void)
4431 {
4432         u8 *p;
4433 
4434         BUILD_BUG_ON(KMALLOC_MIN_SIZE > 16 || KMALLOC_SHIFT_HIGH < 10);
4435 
4436         pr_err("SLUB resiliency testing\n");
4437         pr_err("-----------------------\n");
4438         pr_err("A. Corruption after allocation\n");
4439 
4440         p = kzalloc(16, GFP_KERNEL);
4441         p[16] = 0x12;
4442         pr_err("\n1. kmalloc-16: Clobber Redzone/next pointer 0x12->0x%p\n\n",
4443                p + 16);
4444 
4445         validate_slab_cache(kmalloc_caches[4]);
4446 
4447         /* Hmmm... The next two are dangerous */
4448         p = kzalloc(32, GFP_KERNEL);
4449         p[32 + sizeof(void *)] = 0x34;
4450         pr_err("\n2. kmalloc-32: Clobber next pointer/next slab 0x34 -> -0x%p\n",
4451                p);
4452         pr_err("If allocated object is overwritten then not detectable\n\n");
4453 
4454         validate_slab_cache(kmalloc_caches[5]);
4455         p = kzalloc(64, GFP_KERNEL);
4456         p += 64 + (get_cycles() & 0xff) * sizeof(void *);
4457         *p = 0x56;
4458         pr_err("\n3. kmalloc-64: corrupting random byte 0x56->0x%p\n",
4459                p);
4460         pr_err("If allocated object is overwritten then not detectable\n\n");
4461         validate_slab_cache(kmalloc_caches[6]);
4462 
4463         pr_err("\nB. Corruption after free\n");
4464         p = kzalloc(128, GFP_KERNEL);
4465         kfree(p);
4466         *p = 0x78;
4467         pr_err("1. kmalloc-128: Clobber first word 0x78->0x%p\n\n", p);
4468         validate_slab_cache(kmalloc_caches[7]);
4469 
4470         p = kzalloc(256, GFP_KERNEL);
4471         kfree(p);
4472         p[50] = 0x9a;
4473         pr_err("\n2. kmalloc-256: Clobber 50th byte 0x9a->0x%p\n\n", p);
4474         validate_slab_cache(kmalloc_caches[8]);
4475 
4476         p = kzalloc(512, GFP_KERNEL);
4477         kfree(p);
4478         p[512] = 0xab;
4479         pr_err("\n3. kmalloc-512: Clobber redzone 0xab->0x%p\n\n", p);
4480         validate_slab_cache(kmalloc_caches[9]);
4481 }
4482 #else
4483 #ifdef CONFIG_SYSFS
4484 static void resiliency_test(void) {};
4485 #endif
4486 #endif
4487 
4488 #ifdef CONFIG_SYSFS
4489 enum slab_stat_type {
4490         SL_ALL,                 /* All slabs */
4491         SL_PARTIAL,             /* Only partially allocated slabs */
4492         SL_CPU,                 /* Only slabs used for cpu caches */
4493         SL_OBJECTS,             /* Determine allocated objects not slabs */
4494         SL_TOTAL                /* Determine object capacity not slabs */
4495 };
4496 
4497 #define SO_ALL          (1 << SL_ALL)
4498 #define SO_PARTIAL      (1 << SL_PARTIAL)
4499 #define SO_CPU          (1 << SL_CPU)
4500 #define SO_OBJECTS      (1 << SL_OBJECTS)
4501 #define SO_TOTAL        (1 << SL_TOTAL)
4502 
4503 static ssize_t show_slab_objects(struct kmem_cache *s,
4504                             char *buf, unsigned long flags)
4505 {
4506         unsigned long total = 0;
4507         int node;
4508         int x;
4509         unsigned long *nodes;
4510 
4511         nodes = kzalloc(sizeof(unsigned long) * nr_node_ids, GFP_KERNEL);
4512         if (!nodes)
4513                 return -ENOMEM;
4514 
4515         if (flags & SO_CPU) {
4516                 int cpu;
4517 
4518                 for_each_possible_cpu(cpu) {
4519                         struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab,
4520                                                                cpu);
4521                         int node;
4522                         struct page *page;
4523 
4524                         page = READ_ONCE(c->page);
4525                         if (!page)
4526                                 continue;
4527 
4528                         node = page_to_nid(page);
4529                         if (flags & SO_TOTAL)
4530                                 x = page->objects;
4531                         else if (flags & SO_OBJECTS)
4532                                 x = page->inuse;
4533                         else
4534                                 x = 1;
4535 
4536                         total += x;
4537                         nodes[node] += x;
4538 
4539                         page = READ_ONCE(c->partial);
4540                         if (page) {
4541                                 node = page_to_nid(page);
4542                                 if (flags & SO_TOTAL)
4543                                         WARN_ON_ONCE(1);
4544                                 else if (flags & SO_OBJECTS)
4545                                         WARN_ON_ONCE(1);
4546                                 else
4547                                         x = page->pages;
4548                                 total += x;
4549                                 nodes[node] += x;
4550                         }
4551                 }
4552         }
4553 
4554         get_online_mems();
4555 #ifdef CONFIG_SLUB_DEBUG
4556         if (flags & SO_ALL) {
4557                 struct kmem_cache_node *n;
4558 
4559                 for_each_kmem_cache_node(s, node, n) {
4560 
4561                         if (flags & SO_TOTAL)
4562                                 x = atomic_long_read(&n->total_objects);
4563                         else if (flags & SO_OBJECTS)
4564                                 x = atomic_long_read(&n->total_objects) -
4565                                         count_partial(n, count_free);
4566                         else
4567                                 x = atomic_long_read(&n->nr_slabs);
4568                         total += x;
4569                         nodes[node] += x;
4570                 }
4571 
4572         } else
4573 #endif
4574         if (flags & SO_PARTIAL) {
4575                 struct kmem_cache_node *n;
4576 
4577                 for_each_kmem_cache_node(s, node, n) {
4578                         if (flags & SO_TOTAL)
4579                                 x = count_partial(n, count_total);
4580                         else if (flags & SO_OBJECTS)
4581                                 x = count_partial(n, count_inuse);
4582                         else
4583                                 x = n->nr_partial;
4584                         total += x;
4585                         nodes[node] += x;
4586                 }
4587         }
4588         x = sprintf(buf, "%lu", total);
4589 #ifdef CONFIG_NUMA
4590         for (node = 0; node < nr_node_ids; node++)
4591                 if (nodes[node])
4592                         x += sprintf(buf + x, " N%d=%lu",
4593                                         node, nodes[node]);
4594 #endif
4595         put_online_mems();
4596         kfree(nodes);
4597         return x + sprintf(buf + x, "\n");
4598 }
4599 
4600 #ifdef CONFIG_SLUB_DEBUG
4601 static int any_slab_objects(struct kmem_cache *s)
4602 {
4603         int node;
4604         struct kmem_cache_node *n;
4605 
4606         for_each_kmem_cache_node(s, node, n)
4607                 if (atomic_long_read(&n->total_objects))
4608                         return 1;
4609 
4610         return 0;
4611 }
4612 #endif
4613 
4614 #define to_slab_attr(n) container_of(n, struct slab_attribute, attr)
4615 #define to_slab(n) container_of(n, struct kmem_cache, kobj)
4616 
4617 struct slab_attribute {
4618         struct attribute attr;
4619         ssize_t (*show)(struct kmem_cache *s, char *buf);
4620         ssize_t (*store)(struct kmem_cache *s, const char *x, size_t count);
4621 };
4622 
4623 #define SLAB_ATTR_RO(_name) \
4624         static struct slab_attribute _name##_attr = \
4625         __ATTR(_name, 0400, _name##_show, NULL)
4626 
4627 #define SLAB_ATTR(_name) \
4628         static struct slab_attribute _name##_attr =  \
4629         __ATTR(_name, 0600, _name##_show, _name##_store)
4630 
4631 static ssize_t slab_size_show(struct kmem_cache *s, char *buf)
4632 {
4633         return sprintf(buf, "%d\n", s->size);
4634 }
4635 SLAB_ATTR_RO(slab_size);
4636 
4637 static ssize_t align_show(struct kmem_cache *s, char *buf)
4638 {
4639         return sprintf(buf, "%d\n", s->align);
4640 }
4641 SLAB_ATTR_RO(align);
4642 
4643 static ssize_t object_size_show(struct kmem_cache *s, char *buf)
4644 {
4645         return sprintf(buf, "%d\n", s->object_size);
4646 }
4647 SLAB_ATTR_RO(object_size);
4648 
4649 static ssize_t objs_per_slab_show(struct kmem_cache *s, char *buf)
4650 {
4651         return sprintf(buf, "%d\n", oo_objects(s->oo));
4652 }
4653 SLAB_ATTR_RO(objs_per_slab);
4654 
4655 static ssize_t order_store(struct kmem_cache *s,
4656                                 const char *buf, size_t length)
4657 {
4658         unsigned long order;
4659         int err;
4660 
4661         err = kstrtoul(buf, 10, &order);
4662         if (err)
4663                 return err;
4664 
4665         if (order > slub_max_order || order < slub_min_order)
4666                 return -EINVAL;
4667 
4668         calculate_sizes(s, order);
4669         return length;
4670 }
4671 
4672 static ssize_t order_show(struct kmem_cache *s, char *buf)
4673 {
4674         return sprintf(buf, "%d\n", oo_order(s->oo));
4675 }
4676 SLAB_ATTR(order);
4677 
4678 static ssize_t min_partial_show(struct kmem_cache *s, char *buf)
4679 {
4680         return sprintf(buf, "%lu\n", s->min_partial);
4681 }
4682 
4683 static ssize_t min_partial_store(struct kmem_cache *s, const char *buf,
4684                                  size_t length)
4685 {
4686         unsigned long min;
4687         int err;
4688 
4689         err = kstrtoul(buf, 10, &min);
4690         if (err)
4691                 return err;
4692 
4693         set_min_partial(s, min);
4694         return length;
4695 }
4696 SLAB_ATTR(min_partial);
4697 
4698 static ssize_t cpu_partial_show(struct kmem_cache *s, char *buf)
4699 {
4700         return sprintf(buf, "%u\n", s->cpu_partial);
4701 }
4702 
4703 static ssize_t cpu_partial_store(struct kmem_cache *s, const char *buf,
4704                                  size_t length)
4705 {
4706         unsigned long objects;
4707         int err;
4708 
4709         err = kstrtoul(buf, 10, &objects);
4710         if (err)
4711                 return err;
4712         if (objects && !kmem_cache_has_cpu_partial(s))
4713                 return -EINVAL;
4714 
4715         s->cpu_partial = objects;
4716         flush_all(s);
4717         return length;
4718 }
4719 SLAB_ATTR(cpu_partial);
4720 
4721 static ssize_t ctor_show(struct kmem_cache *s, char *buf)
4722 {
4723         if (!s->ctor)
4724                 return 0;
4725         return sprintf(buf, "%pS\n", s->ctor);
4726 }
4727 SLAB_ATTR_RO(ctor);
4728 
4729 static ssize_t aliases_show(struct kmem_cache *s, char *buf)
4730 {
4731         return sprintf(buf, "%d\n", s->refcount < 0 ? 0 : s->refcount - 1);
4732 }
4733 SLAB_ATTR_RO(aliases);
4734 
4735 static ssize_t partial_show(struct kmem_cache *s, char *buf)
4736 {
4737         return show_slab_objects(s, buf, SO_PARTIAL);
4738 }
4739 SLAB_ATTR_RO(partial);
4740 
4741 static ssize_t cpu_slabs_show(struct kmem_cache *s, char *buf)
4742 {
4743         return show_slab_objects(s, buf, SO_CPU);
4744 }
4745 SLAB_ATTR_RO(cpu_slabs);
4746 
4747 static ssize_t objects_show(struct kmem_cache *s, char *buf)
4748 {
4749         return show_slab_objects(s, buf, SO_ALL|SO_OBJECTS);
4750 }
4751 SLAB_ATTR_RO(objects);
4752 
4753 static ssize_t objects_partial_show(struct kmem_cache *s, char *buf)
4754 {
4755         return show_slab_objects(s, buf, SO_PARTIAL|SO_OBJECTS);
4756 }
4757 SLAB_ATTR_RO(objects_partial);
4758 
4759 static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf)
4760 {
4761         int objects = 0;
4762         int pages = 0;
4763         int cpu;
4764         int len;
4765 
4766         for_each_online_cpu(cpu) {
4767                 struct page *page = per_cpu_ptr(s->cpu_slab, cpu)->partial;
4768 
4769                 if (page) {
4770                         pages += page->pages;
4771                         objects += page->pobjects;
4772                 }
4773         }
4774 
4775         len = sprintf(buf, "%d(%d)", objects, pages);
4776 
4777 #ifdef CONFIG_SMP
4778         for_each_online_cpu(cpu) {
4779                 struct page *page = per_cpu_ptr(s->cpu_slab, cpu) ->partial;
4780 
4781                 if (page && len < PAGE_SIZE - 20)
4782                         len += sprintf(buf + len, " C%d=%d(%d)", cpu,
4783                                 page->pobjects, page->pages);
4784         }
4785 #endif
4786         return len + sprintf(buf + len, "\n");
4787 }
4788 SLAB_ATTR_RO(slabs_cpu_partial);
4789 
4790 static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf)
4791 {
4792         return sprintf(buf, "%d\n", !!(s->flags & SLAB_RECLAIM_ACCOUNT));
4793 }
4794 
4795 static ssize_t reclaim_account_store(struct kmem_cache *s,
4796                                 const char *buf, size_t length)
4797 {
4798         s->flags &= ~SLAB_RECLAIM_ACCOUNT;
4799         if (buf[0] == '1')
4800                 s->flags |= SLAB_RECLAIM_ACCOUNT;
4801         return length;
4802 }
4803 SLAB_ATTR(reclaim_account);
4804 
4805 static ssize_t hwcache_align_show(struct kmem_cache *s, char *buf)
4806 {
4807         return sprintf(buf, "%d\n", !!(s->flags & SLAB_HWCACHE_ALIGN));
4808 }
4809 SLAB_ATTR_RO(hwcache_align);
4810 
4811 #ifdef CONFIG_ZONE_DMA
4812 static ssize_t cache_dma_show(struct kmem_cache *s, char *buf)
4813 {
4814         return sprintf(buf, "%d\n", !!(s->flags & SLAB_CACHE_DMA));
4815 }
4816 SLAB_ATTR_RO(cache_dma);
4817 #endif
4818 
4819 static ssize_t destroy_by_rcu_show(struct kmem_cache *s, char *buf)
4820 {
4821         return sprintf(buf, "%d\n", !!(s->flags & SLAB_DESTROY_BY_RCU));
4822 }
4823 SLAB_ATTR_RO(destroy_by_rcu);
4824 
4825 static ssize_t reserved_show(struct kmem_cache *s, char *buf)
4826 {
4827         return sprintf(buf, "%d\n", s->reserved);
4828 }
4829 SLAB_ATTR_RO(reserved);
4830 
4831 #ifdef CONFIG_SLUB_DEBUG
4832 static ssize_t slabs_show(struct kmem_cache *s, char *buf)
4833 {
4834         return show_slab_objects(s, buf, SO_ALL);
4835 }
4836 SLAB_ATTR_RO(slabs);
4837 
4838 static ssize_t total_objects_show(struct kmem_cache *s, char *buf)
4839 {
4840         return show_slab_objects(s, buf, SO_ALL|SO_TOTAL);
4841 }
4842 SLAB_ATTR_RO(total_objects);
4843 
4844 static ssize_t sanity_checks_show(struct kmem_cache *s, char *buf)
4845 {
4846         return sprintf(buf, "%d\n", !!(s->flags & SLAB_CONSISTENCY_CHECKS));
4847 }
4848 
4849 static ssize_t sanity_checks_store(struct kmem_cache *s,
4850                                 const char *buf, size_t length)
4851 {
4852         s->flags &= ~SLAB_CONSISTENCY_CHECKS;
4853         if (buf[0] == '1') {
4854                 s->flags &= ~__CMPXCHG_DOUBLE;
4855                 s->flags |= SLAB_CONSISTENCY_CHECKS;
4856         }
4857         return length;
4858 }
4859 SLAB_ATTR(sanity_checks);
4860 
4861 static ssize_t trace_show(struct kmem_cache *s, char *buf)
4862 {
4863         return sprintf(buf, "%d\n", !!(s->flags & SLAB_TRACE));
4864 }
4865 
4866 static ssize_t trace_store(struct kmem_cache *s, const char *buf,
4867                                                         size_t length)
4868 {
4869         /*
4870          * Tracing a merged cache is going to give confusing results
4871          * as well as cause other issues like converting a mergeable
4872          * cache into an umergeable one.
4873          */
4874         if (s->refcount > 1)
4875                 return -EINVAL;
4876 
4877         s->flags &= ~SLAB_TRACE;
4878         if (buf[0] == '1') {
4879                 s->flags &= ~__CMPXCHG_DOUBLE;
4880                 s->flags |= SLAB_TRACE;
4881         }
4882         return length;
4883 }
4884 SLAB_ATTR(trace);
4885 
4886 static ssize_t red_zone_show(struct kmem_cache *s, char *buf)
4887 {
4888         return sprintf(buf, "%d\n", !!(s->flags & SLAB_RED_ZONE));
4889 }
4890 
4891 static ssize_t red_zone_store(struct kmem_cache *s,
4892                                 const char *buf, size_t length)
4893 {
4894         if (any_slab_objects(s))
4895                 return -EBUSY;
4896 
4897         s->flags &= ~SLAB_RED_ZONE;
4898         if (buf[0] == '1') {
4899                 s->flags |= SLAB_RED_ZONE;
4900         }
4901         calculate_sizes(s, -1);
4902         return length;
4903 }
4904 SLAB_ATTR(red_zone);
4905 
4906 static ssize_t poison_show(struct kmem_cache *s, char *buf)
4907 {
4908         return sprintf(buf, "%d\n", !!(s->flags & SLAB_POISON));
4909 }
4910 
4911 static ssize_t poison_store(struct kmem_cache *s,
4912                                 const char *buf, size_t length)
4913 {
4914         if (any_slab_objects(s))
4915                 return -EBUSY;
4916 
4917         s->flags &= ~SLAB_POISON;
4918         if (buf[0] == '1') {
4919                 s->flags |= SLAB_POISON;
4920         }
4921         calculate_sizes(s, -1);
4922         return length;
4923 }
4924 SLAB_ATTR(poison);
4925 
4926 static ssize_t store_user_show(struct kmem_cache *s, char *buf)
4927 {
4928         return sprintf(buf, "%d\n", !!(s->flags & SLAB_STORE_USER));
4929 }
4930 
4931 static ssize_t store_user_store(struct kmem_cache *s,
4932                                 const char *buf, size_t length)
4933 {
4934         if (any_slab_objects(s))
4935                 return -EBUSY;
4936 
4937         s->flags &= ~SLAB_STORE_USER;
4938         if (buf[0] == '1') {
4939                 s->flags &= ~__CMPXCHG_DOUBLE;
4940                 s->flags |= SLAB_STORE_USER;
4941         }
4942         calculate_sizes(s, -1);
4943         return length;
4944 }
4945 SLAB_ATTR(store_user);
4946 
4947 static ssize_t validate_show(struct kmem_cache *s, char *buf)
4948 {
4949         return 0;
4950 }
4951 
4952 static ssize_t validate_store(struct kmem_cache *s,
4953                         const char *buf, size_t length)
4954 {
4955         int ret = -EINVAL;
4956 
4957         if (buf[0] == '1') {
4958                 ret = validate_slab_cache(s);
4959                 if (ret >= 0)
4960                         ret = length;
4961         }
4962         return ret;
4963 }
4964 SLAB_ATTR(validate);
4965 
4966 static ssize_t alloc_calls_show(struct kmem_cache *s, char *buf)
4967 {
4968         if (!(s->flags & SLAB_STORE_USER))
4969                 return -ENOSYS;
4970         return list_locations(s, buf, TRACK_ALLOC);
4971 }
4972 SLAB_ATTR_RO(alloc_calls);
4973 
4974 static ssize_t free_calls_show(struct kmem_cache *s, char *buf)
4975 {
4976         if (!(s->flags & SLAB_STORE_USER))
4977                 return -ENOSYS;
4978         return list_locations(s, buf, TRACK_FREE);
4979 }
4980 SLAB_ATTR_RO(free_calls);
4981 #endif /* CONFIG_SLUB_DEBUG */
4982 
4983 #ifdef CONFIG_FAILSLAB
4984 static ssize_t failslab_show(struct kmem_cache *s, char *buf)
4985 {
4986         return sprintf(buf, "%d\n", !!(s->flags & SLAB_FAILSLAB));
4987 }
4988 
4989 static ssize_t failslab_store(struct kmem_cache *s, const char *buf,
4990                                                         size_t length)
4991 {
4992         if (s->refcount > 1)
4993                 return -EINVAL;
4994 
4995         s->flags &= ~SLAB_FAILSLAB;
4996         if (buf[0] == '1')
4997                 s->flags |= SLAB_FAILSLAB;
4998         return length;
4999 }
5000 SLAB_ATTR(failslab);
5001 #endif
5002 
5003 static ssize_t shrink_show(struct kmem_cache *s, char *buf)
5004 {
5005         return 0;
5006 }
5007 
5008 static ssize_t shrink_store(struct kmem_cache *s,
5009                         const char *buf, size_t length)
5010 {
5011         if (buf[0] == '1')
5012                 kmem_cache_shrink(s);
5013         else
5014                 return -EINVAL;
5015         return length;
5016 }
5017 SLAB_ATTR(shrink);
5018 
5019 #ifdef CONFIG_NUMA
5020 static ssize_t remote_node_defrag_ratio_show(struct kmem_cache *s, char *buf)
5021 {
5022         return sprintf(buf, "%d\n", s->remote_node_defrag_ratio / 10);
5023 }
5024 
5025 static ssize_t remote_node_defrag_ratio_store(struct kmem_cache *s,
5026                                 const char *buf, size_t length)
5027 {
5028         unsigned long ratio;
5029         int err;
5030 
5031         err = kstrtoul(buf, 10, &ratio);
5032         if (err)
5033                 return err;
5034 
5035         if (ratio <= 100)
5036                 s->remote_node_defrag_ratio = ratio * 10;
5037 
5038         return length;
5039 }
5040 SLAB_ATTR(remote_node_defrag_ratio);
5041 #endif
5042 
5043 #ifdef CONFIG_SLUB_STATS
5044 static int show_stat(struct kmem_cache *s, char *buf, enum stat_item si)
5045 {
5046         unsigned long sum  = 0;
5047         int cpu;
5048         int len;
5049         int *data = kmalloc(nr_cpu_ids * sizeof(int), GFP_KERNEL);
5050 
5051         if (!data)
5052                 return -ENOMEM;
5053 
5054         for_each_online_cpu(cpu) {
5055                 unsigned x = per_cpu_ptr(s->cpu_slab, cpu)->stat[si];
5056 
5057                 data[cpu] = x;
5058                 sum += x;
5059         }
5060 
5061         len = sprintf(buf, "%lu", sum);
5062 
5063 #ifdef CONFIG_SMP
5064         for_each_online_cpu(cpu) {
5065                 if (data[cpu] && len < PAGE_SIZE - 20)
5066                         len += sprintf(buf + len, " C%d=%u", cpu, data[cpu]);
5067         }
5068 #endif
5069         kfree(data);
5070         return len + sprintf(buf + len, "\n");
5071 }
5072 
5073 static void clear_stat(struct kmem_cache *s, enum stat_item si)
5074 {
5075         int cpu;
5076 
5077         for_each_online_cpu(cpu)
5078                 per_cpu_ptr(s->cpu_slab, cpu)->stat[si] = 0;
5079 }
5080 
5081 #define STAT_ATTR(si, text)                                     \
5082 static ssize_t text##_show(struct kmem_cache *s, char *buf)     \
5083 {                                                               \
5084         return show_stat(s, buf, si);                           \
5085 }                                                               \
5086 static ssize_t text##_store(struct kmem_cache *s,               \
5087                                 const char *buf, size_t length) \
5088 {                                                               \
5089         if (buf[0] != '')                                      \
5090                 return -EINVAL;                                 \
5091         clear_stat(s, si);                                      \
5092         return length;                                          \
5093 }                                                               \
5094 SLAB_ATTR(text);                                                \
5095 
5096 STAT_ATTR(ALLOC_FASTPATH, alloc_fastpath);
5097 STAT_ATTR(ALLOC_SLOWPATH, alloc_slowpath);
5098 STAT_ATTR(FREE_FASTPATH, free_fastpath);
5099 STAT_ATTR(FREE_SLOWPATH, free_slowpath);
5100 STAT_ATTR(FREE_FROZEN, free_frozen);
5101 STAT_ATTR(FREE_ADD_PARTIAL, free_add_partial);
5102 STAT_ATTR(FREE_REMOVE_PARTIAL, free_remove_partial);
5103 STAT_ATTR(ALLOC_FROM_PARTIAL, alloc_from_partial);
5104 STAT_ATTR(ALLOC_SLAB, alloc_slab);
5105 STAT_ATTR(ALLOC_REFILL, alloc_refill);
5106 STAT_ATTR(ALLOC_NODE_MISMATCH, alloc_node_mismatch);
5107 STAT_ATTR(FREE_SLAB, free_slab);
5108 STAT_ATTR(CPUSLAB_FLUSH, cpuslab_flush);
5109 STAT_ATTR(DEACTIVATE_FULL, deactivate_full);
5110 STAT_ATTR(DEACTIVATE_EMPTY, deactivate_empty);
5111 STAT_ATTR(DEACTIVATE_TO_HEAD, deactivate_to_head);
5112 STAT_ATTR(DEACTIVATE_TO_TAIL, deactivate_to_tail);
5113 STAT_ATTR(DEACTIVATE_REMOTE_FREES, deactivate_remote_frees);
5114 STAT_ATTR(DEACTIVATE_BYPASS, deactivate_bypass);
5115 STAT_ATTR(ORDER_FALLBACK, order_fallback);
5116 STAT_ATTR(CMPXCHG_DOUBLE_CPU_FAIL, cmpxchg_double_cpu_fail);
5117 STAT_ATTR(CMPXCHG_DOUBLE_FAIL, cmpxchg_double_fail);
5118 STAT_ATTR(CPU_PARTIAL_ALLOC, cpu_partial_alloc);
5119 STAT_ATTR(CPU_PARTIAL_FREE, cpu_partial_free);
5120 STAT_ATTR(CPU_PARTIAL_NODE, cpu_partial_node);
5121 STAT_ATTR(CPU_PARTIAL_DRAIN, cpu_partial_drain);
5122 #endif
5123 
5124 static struct attribute *slab_attrs[] = {
5125         &slab_size_attr.attr,
5126         &object_size_attr.attr,
5127         &objs_per_slab_attr.attr,
5128         &order_attr.attr,
5129         &min_partial_attr.attr,
5130         &cpu_partial_attr.attr,
5131         &objects_attr.attr,
5132         &objects_partial_attr.attr,
5133         &partial_attr.attr,
5134         &cpu_slabs_attr.attr,
5135         &ctor_attr.attr,
5136         &aliases_attr.attr,
5137         &align_attr.attr,
5138         &hwcache_align_attr.attr,
5139         &reclaim_account_attr.attr,
5140         &destroy_by_rcu_attr.attr,
5141         &shrink_attr.attr,
5142         &reserved_attr.attr,
5143         &slabs_cpu_partial_attr.attr,
5144 #ifdef CONFIG_SLUB_DEBUG
5145         &total_objects_attr.attr,
5146         &slabs_attr.attr,
5147         &sanity_checks_attr.attr,
5148         &trace_attr.attr,
5149         &red_zone_attr.attr,
5150         &poison_attr.attr,
5151         &store_user_attr.attr,
5152         &validate_attr.attr,
5153         &alloc_calls_attr.attr,
5154         &free_calls_attr.attr,
5155 #endif
5156 #ifdef CONFIG_ZONE_DMA
5157         &cache_dma_attr.attr,
5158 #endif
5159 #ifdef CONFIG_NUMA
5160         &remote_node_defrag_ratio_attr.attr,
5161 #endif
5162 #ifdef CONFIG_SLUB_STATS
5163         &alloc_fastpath_attr.attr,
5164         &alloc_slowpath_attr.attr,
5165         &free_fastpath_attr.attr,
5166         &free_slowpath_attr.attr,
5167         &free_frozen_attr.attr,
5168         &free_add_partial_attr.attr,
5169         &free_remove_partial_attr.attr,
5170         &alloc_from_partial_attr.attr,
5171         &alloc_slab_attr.attr,
5172         &alloc_refill_attr.attr,
5173         &alloc_node_mismatch_attr.attr,
5174         &free_slab_attr.attr,
5175         &cpuslab_flush_attr.attr,
5176         &deactivate_full_attr.attr,
5177         &deactivate_empty_attr.attr,
5178         &deactivate_to_head_attr.attr,
5179         &deactivate_to_tail_attr.attr,
5180         &deactivate_remote_frees_attr.attr,
5181         &deactivate_bypass_attr.attr,
5182         &order_fallback_attr.attr,
5183         &cmpxchg_double_fail_attr.attr,
5184         &cmpxchg_double_cpu_fail_attr.attr,
5185         &cpu_partial_alloc_attr.attr,
5186         &cpu_partial_free_attr.attr,
5187         &cpu_partial_node_attr.attr,
5188         &cpu_partial_drain_attr.attr,
5189 #endif
5190 #ifdef CONFIG_FAILSLAB
5191         &failslab_attr.attr,
5192 #endif
5193 
5194         NULL
5195 };
5196 
5197 static struct attribute_group slab_attr_group = {
5198         .attrs = slab_attrs,
5199 };
5200 
5201 static ssize_t slab_attr_show(struct kobject *kobj,
5202                                 struct attribute *attr,
5203                                 char *buf)
5204 {
5205         struct slab_attribute *attribute;
5206         struct kmem_cache *s;
5207         int err;
5208 
5209         attribute = to_slab_attr(attr);
5210         s = to_slab(kobj);
5211 
5212         if (!attribute->show)
5213                 return -EIO;
5214 
5215         err = attribute->show(s, buf);
5216 
5217         return err;
5218 }
5219 
5220 static ssize_t slab_attr_store(struct kobject *kobj,
5221                                 struct attribute *attr,
5222                                 const char *buf, size_t len)
5223 {
5224         struct slab_attribute *attribute;
5225         struct kmem_cache *s;
5226         int err;
5227 
5228         attribute = to_slab_attr(attr);
5229         s = to_slab(kobj);
5230 
5231         if (!attribute->store)
5232                 return -EIO;
5233 
5234         err = attribute->store(s, buf, len);
5235 #ifdef CONFIG_MEMCG
5236         if (slab_state >= FULL && err >= 0 && is_root_cache(s)) {
5237                 struct kmem_cache *c;
5238 
5239                 mutex_lock(&slab_mutex);
5240                 if (s->max_attr_size < len)
5241                         s->max_attr_size = len;
5242 
5243                 /*
5244                  * This is a best effort propagation, so this function's return
5245                  * value will be determined by the parent cache only. This is
5246                  * basically because not all attributes will have a well
5247                  * defined semantics for rollbacks - most of the actions will
5248                  * have permanent effects.
5249                  *
5250                  * Returning the error value of any of the children that fail
5251                  * is not 100 % defined, in the sense that users seeing the
5252                  * error code won't be able to know anything about the state of
5253                  * the cache.
5254                  *
5255                  * Only returning the error code for the parent cache at least
5256                  * has well defined semantics. The cache being written to
5257                  * directly either failed or succeeded, in which case we loop
5258                  * through the descendants with best-effort propagation.
5259                  */
5260                 for_each_memcg_cache(c, s)
5261                         attribute->store(c, buf, len);
5262                 mutex_unlock(&slab_mutex);
5263         }
5264 #endif
5265         return err;
5266 }
5267 
5268 static void memcg_propagate_slab_attrs(struct kmem_cache *s)
5269 {
5270 #ifdef CONFIG_MEMCG
5271         int i;
5272         char *buffer = NULL;
5273         struct kmem_cache *root_cache;
5274 
5275         if (is_root_cache(s))
5276                 return;
5277 
5278         root_cache = s->memcg_params.root_cache;
5279 
5280         /*
5281          * This mean this cache had no attribute written. Therefore, no point
5282          * in copying default values around
5283          */
5284         if (!root_cache->max_attr_size)
5285                 return;
5286 
5287         for (i = 0; i < ARRAY_SIZE(slab_attrs); i++) {
5288                 char mbuf[64];
5289                 char *buf;
5290                 struct slab_attribute *attr = to_slab_attr(slab_attrs[i]);
5291 
5292                 if (!attr || !attr->store || !attr->show)
5293                         continue;
5294 
5295                 /*
5296                  * It is really bad that we have to allocate here, so we will
5297                  * do it only as a fallback. If we actually allocate, though,
5298                  * we can just use the allocated buffer until the end.
5299                  *
5300                  * Most of the slub attributes will tend to be very small in
5301                  * size, but sysfs allows buffers up to a page, so they can
5302                  * theoretically happen.
5303                  */
5304                 if (buffer)
5305                         buf = buffer;
5306                 else if (root_cache->max_attr_size < ARRAY_SIZE(mbuf))
5307                         buf = mbuf;
5308                 else {
5309                         buffer = (char *) get_zeroed_page(GFP_KERNEL);
5310                         if (WARN_ON(!buffer))
5311                                 continue;
5312                         buf = buffer;
5313                 }
5314 
5315                 attr->show(root_cache, buf);
5316                 attr->store(s, buf, strlen(buf));
5317         }
5318 
5319         if (buffer)
5320                 free_page((unsigned long)buffer);
5321 #endif
5322 }
5323 
5324 static void kmem_cache_release(struct kobject *k)
5325 {
5326         slab_kmem_cache_release(to_slab(k));
5327 }
5328 
5329 static const struct sysfs_ops slab_sysfs_ops = {
5330         .show = slab_attr_show,
5331         .store = slab_attr_store,
5332 };
5333 
5334 static struct kobj_type slab_ktype = {
5335         .sysfs_ops = &slab_sysfs_ops,
5336         .release = kmem_cache_release,
5337 };
5338 
5339 static int uevent_filter(struct kset *kset, struct kobject *kobj)
5340 {
5341         struct kobj_type *ktype = get_ktype(kobj);
5342 
5343         if (ktype == &slab_ktype)
5344                 return 1;
5345         return 0;
5346 }
5347 
5348 static const struct kset_uevent_ops slab_uevent_ops = {
5349         .filter = uevent_filter,
5350 };
5351 
5352 static struct kset *slab_kset;
5353 
5354 static inline struct kset *cache_kset(struct kmem_cache *s)
5355 {
5356 #ifdef CONFIG_MEMCG
5357         if (!is_root_cache(s))
5358                 return s->memcg_params.root_cache->memcg_kset;
5359 #endif
5360         return slab_kset;
5361 }
5362 
5363 #define ID_STR_LENGTH 64
5364 
5365 /* Create a unique string id for a slab cache:
5366  *
5367  * Format       :[flags-]size
5368  */
5369 static char *create_unique_id(struct kmem_cache *s)
5370 {
5371         char *name = kmalloc(ID_STR_LENGTH, GFP_KERNEL);
5372         char *p = name;
5373 
5374         BUG_ON(!name);
5375 
5376         *p++ = ':';
5377         /*
5378          * First flags affecting slabcache operations. We will only
5379          * get here for aliasable slabs so we do not need to support
5380          * too many flags. The flags here must cover all flags that
5381          * are matched during merging to guarantee that the id is
5382          * unique.
5383          */
5384         if (s->flags & SLAB_CACHE_DMA)
5385                 *p++ = 'd';
5386         if (s->flags & SLAB_RECLAIM_ACCOUNT)
5387                 *p++ = 'a';
5388         if (s->flags & SLAB_CONSISTENCY_CHECKS)
5389                 *p++ = 'F';
5390         if (!(s->flags & SLAB_NOTRACK))
5391                 *p++ = 't';
5392         if (s->flags & SLAB_ACCOUNT)
5393                 *p++ = 'A';
5394         if (p != name + 1)
5395                 *p++ = '-';
5396         p += sprintf(p, "%07d", s->size);
5397 
5398         BUG_ON(p > name + ID_STR_LENGTH - 1);
5399         return name;
5400 }
5401 
5402 static int sysfs_slab_add(struct kmem_cache *s)
5403 {
5404         int err;
5405         const char *name;
5406         int unmergeable = slab_unmergeable(s);
5407 
5408         if (unmergeable) {
5409                 /*
5410                  * Slabcache can never be merged so we can use the name proper.
5411                  * This is typically the case for debug situations. In that
5412                  * case we can catch duplicate names easily.
5413                  */
5414                 sysfs_remove_link(&slab_kset->kobj, s->name);
5415                 name = s->name;
5416         } else {
5417                 /*
5418                  * Create a unique name for the slab as a target
5419                  * for the symlinks.
5420                  */
5421                 name = create_unique_id(s);
5422         }
5423 
5424         s->kobj.kset = cache_kset(s);
5425         err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name);
5426         if (err)
5427                 goto out;
5428 
5429         err = sysfs_create_group(&s->kobj, &slab_attr_group);
5430         if (err)
5431                 goto out_del_kobj;
5432 
5433 #ifdef CONFIG_MEMCG
5434         if (is_root_cache(s)) {
5435                 s->memcg_kset = kset_create_and_add("cgroup", NULL, &s->kobj);
5436                 if (!s->memcg_kset) {
5437                         err = -ENOMEM;
5438                         goto out_del_kobj;
5439                 }
5440         }
5441 #endif
5442 
5443         kobject_uevent(&s->kobj, KOBJ_ADD);
5444         if (!unmergeable) {
5445                 /* Setup first alias */
5446                 sysfs_slab_alias(s, s->name);
5447         }
5448 out:
5449         if (!unmergeable)
5450                 kfree(name);
5451         return err;
5452 out_del_kobj:
5453         kobject_del(&s->kobj);
5454         goto out;
5455 }
5456 
5457 void sysfs_slab_remove(struct kmem_cache *s)
5458 {
5459         if (slab_state < FULL)
5460                 /*
5461                  * Sysfs has not been setup yet so no need to remove the
5462                  * cache from sysfs.
5463                  */
5464                 return;
5465 
5466 #ifdef CONFIG_MEMCG
5467         kset_unregister(s->memcg_kset);
5468 #endif
5469         kobject_uevent(&s->kobj, KOBJ_REMOVE);
5470         kobject_del(&s->kobj);
5471         kobject_put(&s->kobj);
5472 }
5473 
5474 /*
5475  * Need to buffer aliases during bootup until sysfs becomes
5476  * available lest we lose that information.
5477  */
5478 struct saved_alias {
5479         struct kmem_cache *s;
5480         const char *name;
5481         struct saved_alias *next;
5482 };
5483 
5484 static struct saved_alias *alias_list;
5485 
5486 static int sysfs_slab_alias(struct kmem_cache *s, const char *name)
5487 {
5488         struct saved_alias *al;
5489 
5490         if (slab_state == FULL) {
5491                 /*
5492                  * If we have a leftover link then remove it.
5493                  */
5494                 sysfs_remove_link(&slab_kset->kobj, name);
5495                 return sysfs_create_link(&slab_kset->kobj, &s->kobj, name);
5496         }
5497 
5498         al = kmalloc(sizeof(struct saved_alias), GFP_KERNEL);
5499         if (!al)
5500                 return -ENOMEM;
5501 
5502         al->s = s;
5503         al->name = name;
5504         al->next = alias_list;
5505         alias_list = al;
5506         return 0;
5507 }
5508 
5509 static int __init slab_sysfs_init(void)
5510 {
5511         struct kmem_cache *s;
5512         int err;
5513 
5514         mutex_lock(&slab_mutex);
5515 
5516         slab_kset = kset_create_and_add("slab", &slab_uevent_ops, kernel_kobj);
5517         if (!slab_kset) {
5518                 mutex_unlock(&slab_mutex);
5519                 pr_err("Cannot register slab subsystem.\n");
5520                 return -ENOSYS;
5521         }
5522 
5523         slab_state = FULL;
5524 
5525         list_for_each_entry(s, &slab_caches, list) {
5526                 err = sysfs_slab_add(s);
5527                 if (err)
5528                         pr_err("SLUB: Unable to add boot slab %s to sysfs\n",
5529                                s->name);
5530         }
5531 
5532         while (alias_list) {
5533                 struct saved_alias *al = alias_list;
5534 
5535                 alias_list = alias_list->next;
5536                 err = sysfs_slab_alias(al->s, al->name);
5537                 if (err)
5538                         pr_err("SLUB: Unable to add boot slab alias %s to sysfs\n",
5539                                al->name);
5540                 kfree(al);
5541         }
5542 
5543         mutex_unlock(&slab_mutex);
5544         resiliency_test();
5545         return 0;
5546 }
5547 
5548 __initcall(slab_sysfs_init);
5549 #endif /* CONFIG_SYSFS */
5550 
5551 /*
5552  * The /proc/slabinfo ABI
5553  */
5554 #ifdef CONFIG_SLABINFO
5555 void get_slabinfo(struct kmem_cache *s, struct slabinfo *sinfo)
5556 {
5557         unsigned long nr_slabs = 0;
5558         unsigned long nr_objs = 0;
5559         unsigned long nr_free = 0;
5560         int node;
5561         struct kmem_cache_node *n;
5562 
5563         for_each_kmem_cache_node(s, node, n) {
5564                 nr_slabs += node_nr_slabs(n);
5565                 nr_objs += node_nr_objs(n);
5566                 nr_free += count_partial(n, count_free);
5567         }
5568 
5569         sinfo->active_objs = nr_objs - nr_free;
5570         sinfo->num_objs = nr_objs;
5571         sinfo->active_slabs = nr_slabs;
5572         sinfo->num_slabs = nr_slabs;
5573         sinfo->objects_per_slab = oo_objects(s->oo);
5574         sinfo->cache_order = oo_order(s->oo);
5575 }
5576 
5577 void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s)
5578 {
5579 }
5580 
5581 ssize_t slabinfo_write(struct file *file, const char __user *buffer,
5582                        size_t count, loff_t *ppos)
5583 {
5584         return -EIO;
5585 }
5586 #endif /* CONFIG_SLABINFO */
5587 

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