/* * Slab allocator functions that are independent of the allocator strategy * * (C) 2012 Christoph Lameter <cl@linux.com> */ #include <linux/slab.h> #include <linux/mm.h> #include <linux/poison.h> #include <linux/interrupt.h> #include <linux/memory.h> #include <linux/compiler.h> #include <linux/module.h> #include <linux/cpu.h> #include <linux/uaccess.h> #include <linux/seq_file.h> #include <linux/proc_fs.h> #include <asm/cacheflush.h> #include <asm/tlbflush.h> #include <asm/page.h> #include <linux/memcontrol.h> #include "slab.h" enum slab_state slab_state; LIST_HEAD(slab_caches); DEFINE_MUTEX(slab_mutex); struct kmem_cache *kmem_cache; #ifdef CONFIG_DEBUG_VM static int kmem_cache_sanity_check(struct mem_cgroup *memcg, const char *name, size_t size) { struct kmem_cache *s = NULL; if (!name || in_interrupt() || size < sizeof(void *) || size > KMALLOC_MAX_SIZE) { pr_err("kmem_cache_create(%s) integrity check failed\n", name); return -EINVAL; } list_for_each_entry(s, &slab_caches, list) { char tmp; int res; /* * This happens when the module gets unloaded and doesn't * destroy its slab cache and no-one else reuses the vmalloc * area of the module. Print a warning. */ res = probe_kernel_address(s->name, tmp); if (res) { pr_err("Slab cache with size %d has lost its name\n", s->object_size); continue; } /* * For simplicity, we won't check this in the list of memcg * caches. We have control over memcg naming, and if there * aren't duplicates in the global list, there won't be any * duplicates in the memcg lists as well. */ if (!memcg && !strcmp(s->name, name)) { pr_err("%s (%s): Cache name already exists.\n", __func__, name); dump_stack(); s = NULL; return -EINVAL; } } WARN_ON(strchr(name, ' ')); /* It confuses parsers */ return 0; } #else static inline int kmem_cache_sanity_check(struct mem_cgroup *memcg, const char *name, size_t size) { return 0; } #endif #ifdef CONFIG_MEMCG_KMEM int memcg_update_all_caches(int num_memcgs) { struct kmem_cache *s; int ret = 0; mutex_lock(&slab_mutex); list_for_each_entry(s, &slab_caches, list) { if (!is_root_cache(s)) continue; ret = memcg_update_cache_size(s, num_memcgs); /* * See comment in memcontrol.c, memcg_update_cache_size: * Instead of freeing the memory, we'll just leave the caches * up to this point in an updated state. */ if (ret) goto out; } memcg_update_array_size(num_memcgs); out: mutex_unlock(&slab_mutex); return ret; } #endif /* * Figure out what the alignment of the objects will be given a set of * flags, a user specified alignment and the size of the objects. */ unsigned long calculate_alignment(unsigned long flags, unsigned long align, unsigned long size) { /* * If the user wants hardware cache aligned objects then follow that * suggestion if the object is sufficiently large. * * The hardware cache alignment cannot override the specified * alignment though. If that is greater then use it. */ if (flags & SLAB_HWCACHE_ALIGN) { unsigned long ralign = cache_line_size(); while (size <= ralign / 2) ralign /= 2; align = max(align, ralign); } if (align < ARCH_SLAB_MINALIGN) align = ARCH_SLAB_MINALIGN; return ALIGN(align, sizeof(void *)); } /* * kmem_cache_create - Create a cache. * @name: A string which is used in /proc/slabinfo to identify this cache. * @size: The size of objects to be created in this cache. * @align: The required alignment for the objects. * @flags: SLAB flags * @ctor: A constructor for the objects. * * Returns a ptr to the cache on success, NULL on failure. * Cannot be called within a interrupt, but can be interrupted. * The @ctor is run when new pages are allocated by the cache. * * The flags are * * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5) * to catch references to uninitialised memory. * * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check * for buffer overruns. * * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware * cacheline. This can be beneficial if you're counting cycles as closely * as davem. */ struct kmem_cache * kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size, size_t align, unsigned long flags, void (*ctor)(void *), struct kmem_cache *parent_cache) { struct kmem_cache *s = NULL; int err = 0; get_online_cpus(); mutex_lock(&slab_mutex); if (!kmem_cache_sanity_check(memcg, name, size) == 0) goto out_locked; /* * Some allocators will constraint the set of valid flags to a subset * of all flags. We expect them to define CACHE_CREATE_MASK in this * case, and we'll just provide them with a sanitized version of the * passed flags. */ flags &= CACHE_CREATE_MASK; s = __kmem_cache_alias(memcg, name, size, align, flags, ctor); if (s) goto out_locked; s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL); if (s) { s->object_size = s->size = size; s->align = calculate_alignment(flags, align, size); s->ctor = ctor; if (memcg_register_cache(memcg, s, parent_cache)) { kmem_cache_free(kmem_cache, s); err = -ENOMEM; goto out_locked; } s->name = kstrdup(name, GFP_KERNEL); if (!s->name) { kmem_cache_free(kmem_cache, s); err = -ENOMEM; goto out_locked; } err = __kmem_cache_create(s, flags); if (!err) { s->refcount = 1; list_add(&s->list, &slab_caches); memcg_cache_list_add(memcg, s); } else { kfree(s->name); kmem_cache_free(kmem_cache, s); } } else err = -ENOMEM; out_locked: mutex_unlock(&slab_mutex); put_online_cpus(); if (err) { if (flags & SLAB_PANIC) panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n", name, err); else { printk(KERN_WARNING "kmem_cache_create(%s) failed with error %d", name, err); dump_stack(); } return NULL; } return s; } struct kmem_cache * kmem_cache_create(const char *name, size_t size, size_t align, unsigned long flags, void (*ctor)(void *)) { return kmem_cache_create_memcg(NULL, name, size, align, flags, ctor, NULL); } EXPORT_SYMBOL(kmem_cache_create); void kmem_cache_destroy(struct kmem_cache *s) { /* Destroy all the children caches if we aren't a memcg cache */ kmem_cache_destroy_memcg_children(s); get_online_cpus(); mutex_lock(&slab_mutex); s->refcount--; if (!s->refcount) { list_del(&s->list); if (!__kmem_cache_shutdown(s)) { mutex_unlock(&slab_mutex); if (s->flags & SLAB_DESTROY_BY_RCU) rcu_barrier(); memcg_release_cache(s); kfree(s->name); kmem_cache_free(kmem_cache, s); } else { list_add(&s->list, &slab_caches); mutex_unlock(&slab_mutex); printk(KERN_ERR "kmem_cache_destroy %s: Slab cache still has objects\n", s->name); dump_stack(); } } else { mutex_unlock(&slab_mutex); } put_online_cpus(); } EXPORT_SYMBOL(kmem_cache_destroy); int slab_is_available(void) { return slab_state >= UP; } #ifndef CONFIG_SLOB /* Create a cache during boot when no slab services are available yet */ void __init create_boot_cache(struct kmem_cache *s, const char *name, size_t size, unsigned long flags) { int err; s->name = name; s->size = s->object_size = size; s->align = calculate_alignment(flags, ARCH_KMALLOC_MINALIGN, size); err = __kmem_cache_create(s, flags); if (err) panic("Creation of kmalloc slab %s size=%zu failed. Reason %d\n", name, size, err); s->refcount = -1; /* Exempt from merging for now */ } struct kmem_cache *__init create_kmalloc_cache(const char *name, size_t size, unsigned long flags) { struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT); if (!s) panic("Out of memory when creating slab %s\n", name); create_boot_cache(s, name, size, flags); list_add(&s->list, &slab_caches); s->refcount = 1; return s; } struct kmem_cache *kmalloc_caches[KMALLOC_SHIFT_HIGH + 1]; EXPORT_SYMBOL(kmalloc_caches); #ifdef CONFIG_ZONE_DMA struct kmem_cache *kmalloc_dma_caches[KMALLOC_SHIFT_HIGH + 1]; EXPORT_SYMBOL(kmalloc_dma_caches); #endif /* * Conversion table for small slabs sizes / 8 to the index in the * kmalloc array. This is necessary for slabs < 192 since we have non power * of two cache sizes there. The size of larger slabs can be determined using * fls. */ static s8 size_index[24] = { 3, /* 8 */ 4, /* 16 */ 5, /* 24 */ 5, /* 32 */ 6, /* 40 */ 6, /* 48 */ 6, /* 56 */ 6, /* 64 */ 1, /* 72 */ 1, /* 80 */ 1, /* 88 */ 1, /* 96 */ 7, /* 104 */ 7, /* 112 */ 7, /* 120 */ 7, /* 128 */ 2, /* 136 */ 2, /* 144 */ 2, /* 152 */ 2, /* 160 */ 2, /* 168 */ 2, /* 176 */ 2, /* 184 */ 2 /* 192 */ }; static inline int size_index_elem(size_t bytes) { return (bytes - 1) / 8; } /* * Find the kmem_cache structure that serves a given size of * allocation */ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags) { int index; if (WARN_ON_ONCE(size > KMALLOC_MAX_SIZE)) return NULL; if (size <= 192) { if (!size) return ZERO_SIZE_PTR; index = size_index[size_index_elem(size)]; } else index = fls(size - 1); #ifdef CONFIG_ZONE_DMA if (unlikely((flags & GFP_DMA))) return kmalloc_dma_caches[index]; #endif return kmalloc_caches[index]; } /* * Create the kmalloc array. Some of the regular kmalloc arrays * may already have been created because they were needed to * enable allocations for slab creation. */ void __init create_kmalloc_caches(unsigned long flags) { int i; /* * Patch up the size_index table if we have strange large alignment * requirements for the kmalloc array. This is only the case for * MIPS it seems. The standard arches will not generate any code here. * * Largest permitted alignment is 256 bytes due to the way we * handle the index determination for the smaller caches. * * Make sure that nothing crazy happens if someone starts tinkering * around with ARCH_KMALLOC_MINALIGN */ BUILD_BUG_ON(KMALLOC_MIN_SIZE > 256 || (KMALLOC_MIN_SIZE & (KMALLOC_MIN_SIZE - 1))); for (i = 8; i < KMALLOC_MIN_SIZE; i += 8) { int elem = size_index_elem(i); if (elem >= ARRAY_SIZE(size_index)) break; size_index[elem] = KMALLOC_SHIFT_LOW; } if (KMALLOC_MIN_SIZE >= 64) { /* * The 96 byte size cache is not used if the alignment * is 64 byte. */ for (i = 64 + 8; i <= 96; i += 8) size_index[size_index_elem(i)] = 7; } if (KMALLOC_MIN_SIZE >= 128) { /* * The 192 byte sized cache is not used if the alignment * is 128 byte. Redirect kmalloc to use the 256 byte cache * instead. */ for (i = 128 + 8; i <= 192; i += 8) size_index[size_index_elem(i)] = 8; } for (i = KMALLOC_SHIFT_LOW; i <= KMALLOC_SHIFT_HIGH; i++) { if (!kmalloc_caches[i]) { kmalloc_caches[i] = create_kmalloc_cache(NULL, 1 << i, flags); } /* * Caches that are not of the two-to-the-power-of size. * These have to be created immediately after the * earlier power of two caches */ if (KMALLOC_MIN_SIZE <= 32 && !kmalloc_caches[1] && i == 6) kmalloc_caches[1] = create_kmalloc_cache(NULL, 96, flags); if (KMALLOC_MIN_SIZE <= 64 && !kmalloc_caches[2] && i == 7) kmalloc_caches[2] = create_kmalloc_cache(NULL, 192, flags); } /* Kmalloc array is now usable */ slab_state = UP; for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) { struct kmem_cache *s = kmalloc_caches[i]; char *n; if (s) { n = kasprintf(GFP_NOWAIT, "kmalloc-%d", kmalloc_size(i)); BUG_ON(!n); s->name = n; } } #ifdef CONFIG_ZONE_DMA for (i = 0; i <= KMALLOC_SHIFT_HIGH; i++) { struct kmem_cache *s = kmalloc_caches[i]; if (s) { int size = kmalloc_size(i); char *n = kasprintf(GFP_NOWAIT, "dma-kmalloc-%d", size); BUG_ON(!n); kmalloc_dma_caches[i] = create_kmalloc_cache(n, size, SLAB_CACHE_DMA | flags); } } #endif } #endif /* !CONFIG_SLOB */ #ifdef CONFIG_SLABINFO void print_slabinfo_header(struct seq_file *m) { /* * Output format version, so at least we can change it * without _too_ many complaints. */ #ifdef CONFIG_DEBUG_SLAB seq_puts(m, "slabinfo - version: 2.1 (statistics)\n"); #else seq_puts(m, "slabinfo - version: 2.1\n"); #endif seq_puts(m, "# name <active_objs> <num_objs> <objsize> " "<objperslab> <pagesperslab>"); seq_puts(m, " : tunables <limit> <batchcount> <sharedfactor>"); seq_puts(m, " : slabdata <active_slabs> <num_slabs> <sharedavail>"); #ifdef CONFIG_DEBUG_SLAB seq_puts(m, " : globalstat <listallocs> <maxobjs> <grown> <reaped> " "<error> <maxfreeable> <nodeallocs> <remotefrees> <alienoverflow>"); seq_puts(m, " : cpustat <allochit> <allocmiss> <freehit> <freemiss>"); #endif seq_putc(m, '\n'); } static void *s_start(struct seq_file *m, loff_t *pos) { loff_t n = *pos; mutex_lock(&slab_mutex); if (!n) print_slabinfo_header(m); return seq_list_start(&slab_caches, *pos); } static void *s_next(struct seq_file *m, void *p, loff_t *pos) { return seq_list_next(p, &slab_caches, pos); } static void s_stop(struct seq_file *m, void *p) { mutex_unlock(&slab_mutex); } static void memcg_accumulate_slabinfo(struct kmem_cache *s, struct slabinfo *info) { struct kmem_cache *c; struct slabinfo sinfo; int i; if (!is_root_cache(s)) return; for_each_memcg_cache_index(i) { c = cache_from_memcg(s, i); if (!c) continue; memset(&sinfo, 0, sizeof(sinfo)); get_slabinfo(c, &sinfo); info->active_slabs += sinfo.active_slabs; info->num_slabs += sinfo.num_slabs; info->shared_avail += sinfo.shared_avail; info->active_objs += sinfo.active_objs; info->num_objs += sinfo.num_objs; } } int cache_show(struct kmem_cache *s, struct seq_file *m) { struct slabinfo sinfo; memset(&sinfo, 0, sizeof(sinfo)); get_slabinfo(s, &sinfo); memcg_accumulate_slabinfo(s, &sinfo); seq_printf(m, "%-17s %6lu %6lu %6u %4u %4d", cache_name(s), sinfo.active_objs, sinfo.num_objs, s->size, sinfo.objects_per_slab, (1 << sinfo.cache_order)); seq_printf(m, " : tunables %4u %4u %4u", sinfo.limit, sinfo.batchcount, sinfo.shared); seq_printf(m, " : slabdata %6lu %6lu %6lu", sinfo.active_slabs, sinfo.num_slabs, sinfo.shared_avail); slabinfo_show_stats(m, s); seq_putc(m, '\n'); return 0; } static int s_show(struct seq_file *m, void *p) { struct kmem_cache *s = list_entry(p, struct kmem_cache, list); if (!is_root_cache(s)) return 0; return cache_show(s, m); } /* * slabinfo_op - iterator that generates /proc/slabinfo * * Output layout: * cache-name * num-active-objs * total-objs * object size * num-active-slabs * total-slabs * num-pages-per-slab * + further values on SMP and with statistics enabled */ static const struct seq_operations slabinfo_op = { .start = s_start, .next = s_next, .stop = s_stop, .show = s_show, }; static int slabinfo_open(struct inode *inode, struct file *file) { return seq_open(file, &slabinfo_op); } static const struct file_operations proc_slabinfo_operations = { .open = slabinfo_open, .read = seq_read, .write = slabinfo_write, .llseek = seq_lseek, .release = seq_release, }; static int __init slab_proc_init(void) { proc_create("slabinfo", S_IRUSR, NULL, &proc_slabinfo_operations); return 0; } module_init(slab_proc_init); #endif /* CONFIG_SLABINFO */