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TOMOYO Linux Cross Reference
Linux/mm/slab_common.c

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  1 /*
  2  * Slab allocator functions that are independent of the allocator strategy
  3  *
  4  * (C) 2012 Christoph Lameter <cl@linux.com>
  5  */
  6 #include <linux/slab.h>
  7 
  8 #include <linux/mm.h>
  9 #include <linux/poison.h>
 10 #include <linux/interrupt.h>
 11 #include <linux/memory.h>
 12 #include <linux/compiler.h>
 13 #include <linux/module.h>
 14 #include <linux/cpu.h>
 15 #include <linux/uaccess.h>
 16 #include <linux/seq_file.h>
 17 #include <linux/proc_fs.h>
 18 #include <asm/cacheflush.h>
 19 #include <asm/tlbflush.h>
 20 #include <asm/page.h>
 21 #include <linux/memcontrol.h>
 22 #include <trace/events/kmem.h>
 23 
 24 #include "slab.h"
 25 
 26 enum slab_state slab_state;
 27 LIST_HEAD(slab_caches);
 28 DEFINE_MUTEX(slab_mutex);
 29 struct kmem_cache *kmem_cache;
 30 
 31 #ifdef CONFIG_DEBUG_VM
 32 static int kmem_cache_sanity_check(const char *name, size_t size)
 33 {
 34         struct kmem_cache *s = NULL;
 35 
 36         if (!name || in_interrupt() || size < sizeof(void *) ||
 37                 size > KMALLOC_MAX_SIZE) {
 38                 pr_err("kmem_cache_create(%s) integrity check failed\n", name);
 39                 return -EINVAL;
 40         }
 41 
 42         list_for_each_entry(s, &slab_caches, list) {
 43                 char tmp;
 44                 int res;
 45 
 46                 /*
 47                  * This happens when the module gets unloaded and doesn't
 48                  * destroy its slab cache and no-one else reuses the vmalloc
 49                  * area of the module.  Print a warning.
 50                  */
 51                 res = probe_kernel_address(s->name, tmp);
 52                 if (res) {
 53                         pr_err("Slab cache with size %d has lost its name\n",
 54                                s->object_size);
 55                         continue;
 56                 }
 57 
 58 #if !defined(CONFIG_SLUB)
 59                 if (!strcmp(s->name, name)) {
 60                         pr_err("%s (%s): Cache name already exists.\n",
 61                                __func__, name);
 62                         dump_stack();
 63                         s = NULL;
 64                         return -EINVAL;
 65                 }
 66 #endif
 67         }
 68 
 69         WARN_ON(strchr(name, ' '));     /* It confuses parsers */
 70         return 0;
 71 }
 72 #else
 73 static inline int kmem_cache_sanity_check(const char *name, size_t size)
 74 {
 75         return 0;
 76 }
 77 #endif
 78 
 79 #ifdef CONFIG_MEMCG_KMEM
 80 int memcg_update_all_caches(int num_memcgs)
 81 {
 82         struct kmem_cache *s;
 83         int ret = 0;
 84         mutex_lock(&slab_mutex);
 85 
 86         list_for_each_entry(s, &slab_caches, list) {
 87                 if (!is_root_cache(s))
 88                         continue;
 89 
 90                 ret = memcg_update_cache_size(s, num_memcgs);
 91                 /*
 92                  * See comment in memcontrol.c, memcg_update_cache_size:
 93                  * Instead of freeing the memory, we'll just leave the caches
 94                  * up to this point in an updated state.
 95                  */
 96                 if (ret)
 97                         goto out;
 98         }
 99 
100         memcg_update_array_size(num_memcgs);
101 out:
102         mutex_unlock(&slab_mutex);
103         return ret;
104 }
105 #endif
106 
107 /*
108  * Figure out what the alignment of the objects will be given a set of
109  * flags, a user specified alignment and the size of the objects.
110  */
111 unsigned long calculate_alignment(unsigned long flags,
112                 unsigned long align, unsigned long size)
113 {
114         /*
115          * If the user wants hardware cache aligned objects then follow that
116          * suggestion if the object is sufficiently large.
117          *
118          * The hardware cache alignment cannot override the specified
119          * alignment though. If that is greater then use it.
120          */
121         if (flags & SLAB_HWCACHE_ALIGN) {
122                 unsigned long ralign = cache_line_size();
123                 while (size <= ralign / 2)
124                         ralign /= 2;
125                 align = max(align, ralign);
126         }
127 
128         if (align < ARCH_SLAB_MINALIGN)
129                 align = ARCH_SLAB_MINALIGN;
130 
131         return ALIGN(align, sizeof(void *));
132 }
133 
134 static struct kmem_cache *
135 do_kmem_cache_create(char *name, size_t object_size, size_t size, size_t align,
136                      unsigned long flags, void (*ctor)(void *),
137                      struct mem_cgroup *memcg, struct kmem_cache *root_cache)
138 {
139         struct kmem_cache *s;
140         int err;
141 
142         err = -ENOMEM;
143         s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
144         if (!s)
145                 goto out;
146 
147         s->name = name;
148         s->object_size = object_size;
149         s->size = size;
150         s->align = align;
151         s->ctor = ctor;
152 
153         err = memcg_alloc_cache_params(memcg, s, root_cache);
154         if (err)
155                 goto out_free_cache;
156 
157         err = __kmem_cache_create(s, flags);
158         if (err)
159                 goto out_free_cache;
160 
161         s->refcount = 1;
162         list_add(&s->list, &slab_caches);
163 out:
164         if (err)
165                 return ERR_PTR(err);
166         return s;
167 
168 out_free_cache:
169         memcg_free_cache_params(s);
170         kfree(s);
171         goto out;
172 }
173 
174 /*
175  * kmem_cache_create - Create a cache.
176  * @name: A string which is used in /proc/slabinfo to identify this cache.
177  * @size: The size of objects to be created in this cache.
178  * @align: The required alignment for the objects.
179  * @flags: SLAB flags
180  * @ctor: A constructor for the objects.
181  *
182  * Returns a ptr to the cache on success, NULL on failure.
183  * Cannot be called within a interrupt, but can be interrupted.
184  * The @ctor is run when new pages are allocated by the cache.
185  *
186  * The flags are
187  *
188  * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
189  * to catch references to uninitialised memory.
190  *
191  * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
192  * for buffer overruns.
193  *
194  * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
195  * cacheline.  This can be beneficial if you're counting cycles as closely
196  * as davem.
197  */
198 struct kmem_cache *
199 kmem_cache_create(const char *name, size_t size, size_t align,
200                   unsigned long flags, void (*ctor)(void *))
201 {
202         struct kmem_cache *s;
203         char *cache_name;
204         int err;
205 
206         get_online_cpus();
207         get_online_mems();
208 
209         mutex_lock(&slab_mutex);
210 
211         err = kmem_cache_sanity_check(name, size);
212         if (err)
213                 goto out_unlock;
214 
215         /*
216          * Some allocators will constraint the set of valid flags to a subset
217          * of all flags. We expect them to define CACHE_CREATE_MASK in this
218          * case, and we'll just provide them with a sanitized version of the
219          * passed flags.
220          */
221         flags &= CACHE_CREATE_MASK;
222 
223         s = __kmem_cache_alias(name, size, align, flags, ctor);
224         if (s)
225                 goto out_unlock;
226 
227         cache_name = kstrdup(name, GFP_KERNEL);
228         if (!cache_name) {
229                 err = -ENOMEM;
230                 goto out_unlock;
231         }
232 
233         s = do_kmem_cache_create(cache_name, size, size,
234                                  calculate_alignment(flags, align, size),
235                                  flags, ctor, NULL, NULL);
236         if (IS_ERR(s)) {
237                 err = PTR_ERR(s);
238                 kfree(cache_name);
239         }
240 
241 out_unlock:
242         mutex_unlock(&slab_mutex);
243 
244         put_online_mems();
245         put_online_cpus();
246 
247         if (err) {
248                 if (flags & SLAB_PANIC)
249                         panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
250                                 name, err);
251                 else {
252                         printk(KERN_WARNING "kmem_cache_create(%s) failed with error %d",
253                                 name, err);
254                         dump_stack();
255                 }
256                 return NULL;
257         }
258         return s;
259 }
260 EXPORT_SYMBOL(kmem_cache_create);
261 
262 #ifdef CONFIG_MEMCG_KMEM
263 /*
264  * memcg_create_kmem_cache - Create a cache for a memory cgroup.
265  * @memcg: The memory cgroup the new cache is for.
266  * @root_cache: The parent of the new cache.
267  * @memcg_name: The name of the memory cgroup (used for naming the new cache).
268  *
269  * This function attempts to create a kmem cache that will serve allocation
270  * requests going from @memcg to @root_cache. The new cache inherits properties
271  * from its parent.
272  */
273 struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
274                                            struct kmem_cache *root_cache,
275                                            const char *memcg_name)
276 {
277         struct kmem_cache *s = NULL;
278         char *cache_name;
279 
280         get_online_cpus();
281         get_online_mems();
282 
283         mutex_lock(&slab_mutex);
284 
285         cache_name = kasprintf(GFP_KERNEL, "%s(%d:%s)", root_cache->name,
286                                memcg_cache_id(memcg), memcg_name);
287         if (!cache_name)
288                 goto out_unlock;
289 
290         s = do_kmem_cache_create(cache_name, root_cache->object_size,
291                                  root_cache->size, root_cache->align,
292                                  root_cache->flags, root_cache->ctor,
293                                  memcg, root_cache);
294         if (IS_ERR(s)) {
295                 kfree(cache_name);
296                 s = NULL;
297         }
298 
299 out_unlock:
300         mutex_unlock(&slab_mutex);
301 
302         put_online_mems();
303         put_online_cpus();
304 
305         return s;
306 }
307 
308 static int memcg_cleanup_cache_params(struct kmem_cache *s)
309 {
310         int rc;
311 
312         if (!s->memcg_params ||
313             !s->memcg_params->is_root_cache)
314                 return 0;
315 
316         mutex_unlock(&slab_mutex);
317         rc = __memcg_cleanup_cache_params(s);
318         mutex_lock(&slab_mutex);
319 
320         return rc;
321 }
322 #else
323 static int memcg_cleanup_cache_params(struct kmem_cache *s)
324 {
325         return 0;
326 }
327 #endif /* CONFIG_MEMCG_KMEM */
328 
329 void slab_kmem_cache_release(struct kmem_cache *s)
330 {
331         kfree(s->name);
332         kmem_cache_free(kmem_cache, s);
333 }
334 
335 void kmem_cache_destroy(struct kmem_cache *s)
336 {
337         get_online_cpus();
338         get_online_mems();
339 
340         mutex_lock(&slab_mutex);
341 
342         s->refcount--;
343         if (s->refcount)
344                 goto out_unlock;
345 
346         if (memcg_cleanup_cache_params(s) != 0)
347                 goto out_unlock;
348 
349         if (__kmem_cache_shutdown(s) != 0) {
350                 printk(KERN_ERR "kmem_cache_destroy %s: "
351                        "Slab cache still has objects\n", s->name);
352                 dump_stack();
353                 goto out_unlock;
354         }
355 
356         list_del(&s->list);
357 
358         mutex_unlock(&slab_mutex);
359         if (s->flags & SLAB_DESTROY_BY_RCU)
360                 rcu_barrier();
361 
362         memcg_free_cache_params(s);
363 #ifdef SLAB_SUPPORTS_SYSFS
364         sysfs_slab_remove(s);
365 #else
366         slab_kmem_cache_release(s);
367 #endif
368         goto out;
369 
370 out_unlock:
371         mutex_unlock(&slab_mutex);
372 out:
373         put_online_mems();
374         put_online_cpus();
375 }
376 EXPORT_SYMBOL(kmem_cache_destroy);
377 
378 /**
379  * kmem_cache_shrink - Shrink a cache.
380  * @cachep: The cache to shrink.
381  *
382  * Releases as many slabs as possible for a cache.
383  * To help debugging, a zero exit status indicates all slabs were released.
384  */
385 int kmem_cache_shrink(struct kmem_cache *cachep)
386 {
387         int ret;
388 
389         get_online_cpus();
390         get_online_mems();
391         ret = __kmem_cache_shrink(cachep);
392         put_online_mems();
393         put_online_cpus();
394         return ret;
395 }
396 EXPORT_SYMBOL(kmem_cache_shrink);
397 
398 int slab_is_available(void)
399 {
400         return slab_state >= UP;
401 }
402 
403 #ifndef CONFIG_SLOB
404 /* Create a cache during boot when no slab services are available yet */
405 void __init create_boot_cache(struct kmem_cache *s, const char *name, size_t size,
406                 unsigned long flags)
407 {
408         int err;
409 
410         s->name = name;
411         s->size = s->object_size = size;
412         s->align = calculate_alignment(flags, ARCH_KMALLOC_MINALIGN, size);
413         err = __kmem_cache_create(s, flags);
414 
415         if (err)
416                 panic("Creation of kmalloc slab %s size=%zu failed. Reason %d\n",
417                                         name, size, err);
418 
419         s->refcount = -1;       /* Exempt from merging for now */
420 }
421 
422 struct kmem_cache *__init create_kmalloc_cache(const char *name, size_t size,
423                                 unsigned long flags)
424 {
425         struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT);
426 
427         if (!s)
428                 panic("Out of memory when creating slab %s\n", name);
429 
430         create_boot_cache(s, name, size, flags);
431         list_add(&s->list, &slab_caches);
432         s->refcount = 1;
433         return s;
434 }
435 
436 struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1];
437 EXPORT_SYMBOL(kmalloc_caches);
438 
439 #ifdef CONFIG_ZONE_DMA
440 struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1];
441 EXPORT_SYMBOL(kmalloc_dma_caches);
442 #endif
443 
444 /*
445  * Conversion table for small slabs sizes / 8 to the index in the
446  * kmalloc array. This is necessary for slabs < 192 since we have non power
447  * of two cache sizes there. The size of larger slabs can be determined using
448  * fls.
449  */
450 static s8 size_index[24] = {
451         3,      /* 8 */
452         4,      /* 16 */
453         5,      /* 24 */
454         5,      /* 32 */
455         6,      /* 40 */
456         6,      /* 48 */
457         6,      /* 56 */
458         6,      /* 64 */
459         1,      /* 72 */
460         1,      /* 80 */
461         1,      /* 88 */
462         1,      /* 96 */
463         7,      /* 104 */
464         7,      /* 112 */
465         7,      /* 120 */
466         7,      /* 128 */
467         2,      /* 136 */
468         2,      /* 144 */
469         2,      /* 152 */
470         2,      /* 160 */
471         2,      /* 168 */
472         2,      /* 176 */
473         2,      /* 184 */
474         2       /* 192 */
475 };
476 
477 static inline int size_index_elem(size_t bytes)
478 {
479         return (bytes - 1) / 8;
480 }
481 
482 /*
483  * Find the kmem_cache structure that serves a given size of
484  * allocation
485  */
486 struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
487 {
488         int index;
489 
490         if (unlikely(size > KMALLOC_MAX_SIZE)) {
491                 WARN_ON_ONCE(!(flags & __GFP_NOWARN));
492                 return NULL;
493         }
494 
495         if (size <= 192) {
496                 if (!size)
497                         return ZERO_SIZE_PTR;
498 
499                 index = size_index[size_index_elem(size)];
500         } else
501                 index = fls(size - 1);
502 
503 #ifdef CONFIG_ZONE_DMA
504         if (unlikely((flags & GFP_DMA)))
505                 return kmalloc_dma_caches[index];
506 
507 #endif
508         return kmalloc_caches[index];
509 }
510 
511 /*
512  * Create the kmalloc array. Some of the regular kmalloc arrays
513  * may already have been created because they were needed to
514  * enable allocations for slab creation.
515  */
516 void __init create_kmalloc_caches(unsigned long flags)
517 {
518         int i;
519 
520         /*
521          * Patch up the size_index table if we have strange large alignment
522          * requirements for the kmalloc array. This is only the case for
523          * MIPS it seems. The standard arches will not generate any code here.
524          *
525          * Largest permitted alignment is 256 bytes due to the way we
526          * handle the index determination for the smaller caches.
527          *
528          * Make sure that nothing crazy happens if someone starts tinkering
529          * around with ARCH_KMALLOC_MINALIGN
530          */
531         BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 ||
532                 (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1)));
533 
534         for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) {
535                 int elem = size_index_elem(i);
536 
537                 if (elem >= ARRAY_SIZE(size_index))
538                         break;
539                 size_index[elem] = KMALLOC_SHIFT_LOW;
540         }
541 
542         if (KMALLOC_MIN_SIZE >= 64) {
543                 /*
544                  * The 96 byte size cache is not used if the alignment
545                  * is 64 byte.
546                  */
547                 for (i = 64 + 8; i <= 96; i += 8)
548                         size_index[size_index_elem(i)] = 7;
549 
550         }
551 
552         if (KMALLOC_MIN_SIZE >= 128) {
553                 /*
554                  * The 192 byte sized cache is not used if the alignment
555                  * is 128 byte. Redirect kmalloc to use the 256 byte cache
556                  * instead.
557                  */
558                 for (i = 128 + 8; i <= 192; i += 8)
559                         size_index[size_index_elem(i)] = 8;
560         }
561         for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) {
562                 if (!kmalloc_caches[i]) {
563                         kmalloc_caches[i] = create_kmalloc_cache(NULL,
564                                                         1 << i, flags);
565                 }
566 
567                 /*
568                  * Caches that are not of the two-to-the-power-of size.
569                  * These have to be created immediately after the
570                  * earlier power of two caches
571                  */
572                 if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1] && i == 6)
573                         kmalloc_caches[1] = create_kmalloc_cache(NULL, 96, flags);
574 
575                 if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2] && i == 7)
576                         kmalloc_caches[2] = create_kmalloc_cache(NULL, 192, flags);
577         }
578 
579         /* Kmalloc array is now usable */
580         slab_state = UP;
581 
582         for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
583                 struct kmem_cache *s = kmalloc_caches[i];
584                 char *n;
585 
586                 if (s) {
587                         n = kasprintf(GFP_NOWAIT, "kmalloc-%d", kmalloc_size(i));
588 
589                         BUG_ON(!n);
590                         s->name = n;
591                 }
592         }
593 
594 #ifdef CONFIG_ZONE_DMA
595         for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) {
596                 struct kmem_cache *s = kmalloc_caches[i];
597 
598                 if (s) {
599                         int size = kmalloc_size(i);
600                         char *n = kasprintf(GFP_NOWAIT,
601                                  "dma-kmalloc-%d", size);
602 
603                         BUG_ON(!n);
604                         kmalloc_dma_caches[i] = create_kmalloc_cache(n,
605                                 size, SLAB_CACHE_DMA | flags);
606                 }
607         }
608 #endif
609 }
610 #endif /* !CONFIG_SLOB */
611 
612 /*
613  * To avoid unnecessary overhead, we pass through large allocation requests
614  * directly to the page allocator. We use __GFP_COMP, because we will need to
615  * know the allocation order to free the pages properly in kfree.
616  */
617 void *kmalloc_order(size_t size, gfp_t flags, unsigned int order)
618 {
619         void *ret;
620         struct page *page;
621 
622         flags |= __GFP_COMP;
623         page = alloc_kmem_pages(flags, order);
624         ret = page ? page_address(page) : NULL;
625         kmemleak_alloc(ret, size, 1, flags);
626         return ret;
627 }
628 EXPORT_SYMBOL(kmalloc_order);
629 
630 #ifdef CONFIG_TRACING
631 void *kmalloc_order_trace(size_t size, gfp_t flags, unsigned int order)
632 {
633         void *ret = kmalloc_order(size, flags, order);
634         trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << order, flags);
635         return ret;
636 }
637 EXPORT_SYMBOL(kmalloc_order_trace);
638 #endif
639 
640 #ifdef CONFIG_SLABINFO
641 
642 #ifdef CONFIG_SLAB
643 #define SLABINFO_RIGHTS (S_IWUSR | S_IRUSR)
644 #else
645 #define SLABINFO_RIGHTS S_IRUSR
646 #endif
647 
648 void print_slabinfo_header(struct seq_file *m)
649 {
650         /*
651          * Output format version, so at least we can change it
652          * without _too_ many complaints.
653          */
654 #ifdef CONFIG_DEBUG_SLAB
655         seq_puts(m, "slabinfo - version: 2.1 (statistics)\n");
656 #else
657         seq_puts(m, "slabinfo - version: 2.1\n");
658 #endif
659         seq_puts(m, "# name            <active_objs> <num_objs> <objsize> "
660                  "<objperslab> <pagesperslab>");
661         seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>");
662         seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>");
663 #ifdef CONFIG_DEBUG_SLAB
664         seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> "
665                  "<error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>");
666         seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>");
667 #endif
668         seq_putc(m, '\n');
669 }
670 
671 static void *s_start(struct seq_file *m, loff_t *pos)
672 {
673         loff_t n = *pos;
674 
675         mutex_lock(&slab_mutex);
676         if (!n)
677                 print_slabinfo_header(m);
678 
679         return seq_list_start(&slab_caches, *pos);
680 }
681 
682 void *slab_next(struct seq_file *m, void *p, loff_t *pos)
683 {
684         return seq_list_next(p, &slab_caches, pos);
685 }
686 
687 void slab_stop(struct seq_file *m, void *p)
688 {
689         mutex_unlock(&slab_mutex);
690 }
691 
692 static void
693 memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info)
694 {
695         struct kmem_cache *c;
696         struct slabinfo sinfo;
697         int i;
698 
699         if (!is_root_cache(s))
700                 return;
701 
702         for_each_memcg_cache_index(i) {
703                 c = cache_from_memcg_idx(s, i);
704                 if (!c)
705                         continue;
706 
707                 memset(&sinfo, 0, sizeof(sinfo));
708                 get_slabinfo(c, &sinfo);
709 
710                 info->active_slabs += sinfo.active_slabs;
711                 info->num_slabs += sinfo.num_slabs;
712                 info->shared_avail += sinfo.shared_avail;
713                 info->active_objs += sinfo.active_objs;
714                 info->num_objs += sinfo.num_objs;
715         }
716 }
717 
718 int cache_show(struct kmem_cache *s, struct seq_file *m)
719 {
720         struct slabinfo sinfo;
721 
722         memset(&sinfo, 0, sizeof(sinfo));
723         get_slabinfo(s, &sinfo);
724 
725         memcg_accumulate_slabinfo(s, &sinfo);
726 
727         seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d",
728                    cache_name(s), sinfo.active_objs, sinfo.num_objs, s->size,
729                    sinfo.objects_per_slab, (1 << sinfo.cache_order));
730 
731         seq_printf(m, " : tunables %4u %4u %4u",
732                    sinfo.limit, sinfo.batchcount, sinfo.shared);
733         seq_printf(m, " : slabdata %6lu %6lu %6lu",
734                    sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail);
735         slabinfo_show_stats(m, s);
736         seq_putc(m, '\n');
737         return 0;
738 }
739 
740 static int s_show(struct seq_file *m, void *p)
741 {
742         struct kmem_cache *s = list_entry(p, struct kmem_cache, list);
743 
744         if (!is_root_cache(s))
745                 return 0;
746         return cache_show(s, m);
747 }
748 
749 /*
750  * slabinfo_op - iterator that generates /proc/slabinfo
751  *
752  * Output layout:
753  * cache-name
754  * num-active-objs
755  * total-objs
756  * object size
757  * num-active-slabs
758  * total-slabs
759  * num-pages-per-slab
760  * + further values on SMP and with statistics enabled
761  */
762 static const struct seq_operations slabinfo_op = {
763         .start = s_start,
764         .next = slab_next,
765         .stop = slab_stop,
766         .show = s_show,
767 };
768 
769 static int slabinfo_open(struct inode *inode, struct file *file)
770 {
771         return seq_open(file, &slabinfo_op);
772 }
773 
774 static const struct file_operations proc_slabinfo_operations = {
775         .open           = slabinfo_open,
776         .read           = seq_read,
777         .write          = slabinfo_write,
778         .llseek         = seq_lseek,
779         .release        = seq_release,
780 };
781 
782 static int __init slab_proc_init(void)
783 {
784         proc_create("slabinfo", SLABINFO_RIGHTS, NULL,
785                                                 &proc_slabinfo_operations);
786         return 0;
787 }
788 module_init(slab_proc_init);
789 #endif /* CONFIG_SLABINFO */
790 

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