// SPDX-License-Identifier: GPL-2.0 /* * SLUB: A slab allocator that limits cache line use instead of queuing * objects in per cpu and per node lists. * * The allocator synchronizes using per slab locks or atomic operations * and only uses a centralized lock to manage a pool of partial slabs. * * (C) 2007 SGI, Christoph Lameter * (C) 2011 Linux Foundation, Christoph Lameter */ #include #include /* mm_account_reclaimed_pages() */ #include #include #include #include #include #include #include "slab.h" #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "internal.h" /* * Lock order: * 1. slab_mutex (Global Mutex) * 2. node->list_lock (Spinlock) * 3. kmem_cache->cpu_slab->lock (Local lock) * 4. slab_lock(slab) (Only on some arches) * 5. object_map_lock (Only for debugging) * * slab_mutex * * The role of the slab_mutex is to protect the list of all the slabs * and to synchronize major metadata changes to slab cache structures. * Also synchronizes memory hotplug callbacks. * * slab_lock * * The slab_lock is a wrapper around the page lock, thus it is a bit * spinlock. * * The slab_lock is only used on arches that do not have the ability * to do a cmpxchg_double. It only protects: * * A. slab->freelist -> List of free objects in a slab * B. slab->inuse -> Number of objects in use * C. slab->objects -> Number of objects in slab * D. slab->frozen -> frozen state * * Frozen slabs * * If a slab is frozen then it is exempt from list management. It is * the cpu slab which is actively allocated from by the processor that * froze it and it is not on any list. The processor that froze the * slab is the one who can perform list operations on the slab. Other * processors may put objects onto the freelist but the processor that * froze the slab is the only one that can retrieve the objects from the * slab's freelist. * * CPU partial slabs * * The partially empty slabs cached on the CPU partial list are used * for performance reasons, which speeds up the allocation process. * These slabs are not frozen, but are also exempt from list management, * by clearing the PG_workingset flag when moving out of the node * partial list. Please see __slab_free() for more details. * * To sum up, the current scheme is: * - node partial slab: PG_Workingset && !frozen * - cpu partial slab: !PG_Workingset && !frozen * - cpu slab: !PG_Workingset && frozen * - full slab: !PG_Workingset && !frozen * * list_lock * * The list_lock protects the partial and full list on each node and * the partial slab counter. If taken then no new slabs may be added or * removed from the lists nor make the number of partial slabs be modified. * (Note that the total number of slabs is an atomic value that may be * modified without taking the list lock). * * The list_lock is a centralized lock and thus we avoid taking it as * much as possible. As long as SLUB does not have to handle partial * slabs, operations can continue without any centralized lock. F.e. * allocating a long series of objects that fill up slabs does not require * the list lock. * * For debug caches, all allocations are forced to go through a list_lock * protected region to serialize against concurrent validation. * * cpu_slab->lock local lock * * This locks protect slowpath manipulation of all kmem_cache_cpu fields * except the stat counters. This is a percpu structure manipulated only by * the local cpu, so the lock protects against being preempted or interrupted * by an irq. Fast path operations rely on lockless operations instead. * * On PREEMPT_RT, the local lock neither disables interrupts nor preemption * which means the lockless fastpath cannot be used as it might interfere with * an in-progress slow path operations. In this case the local lock is always * taken but it still utilizes the freelist for the common operations. * * lockless fastpaths * * The fast path allocation (slab_alloc_node()) and freeing (do_slab_free()) * are fully lockless when satisfied from the percpu slab (and when * cmpxchg_double is possible to use, otherwise slab_lock is taken). * They also don't disable preemption or migration or irqs. They rely on * the transaction id (tid) field to detect being preempted or moved to * another cpu. * * irq, preemption, migration considerations * * Interrupts are disabled as part of list_lock or local_lock operations, or * around the slab_lock operation, in order to make the slab allocator safe * to use in the context of an irq. * * In addition, preemption (or migration on PREEMPT_RT) is disabled in the * allocation slowpath, bulk allocation, and put_cpu_partial(), so that the * local cpu doesn't change in the process and e.g. the kmem_cache_cpu pointer * doesn't have to be revalidated in each section protected by the local lock. * * SLUB assigns one slab for allocation to each processor. * Allocations only occur from these slabs called cpu slabs. * * Slabs with free elements are kept on a partial list and during regular * operations no list for full slabs is used. If an object in a full slab is * freed then the slab will show up again on the partial lists. * We track full slabs for debugging purposes though because otherwise we * cannot scan all objects. * * Slabs are freed when they become empty. Teardown and setup is * minimal so we rely on the page allocators per cpu caches for * fast frees and allocs. * * slab->frozen The slab is frozen and exempt from list processing. * This means that the slab is dedicated to a purpose * such as satisfying allocations for a specific * processor. Objects may be freed in the slab while * it is frozen but slab_free will then skip the usual * list operations. It is up to the processor holding * the slab to integrate the slab into the slab lists * when the slab is no longer needed. * * One use of this flag is to mark slabs that are * used for allocations. Then such a slab becomes a cpu * slab. The cpu slab may be equipped with an additional * freelist that allows lockless access to * free objects in addition to the regular freelist * that requires the slab lock. * * SLAB_DEBUG_FLAGS Slab requires special handling due to debug * options set. This moves slab handling out of * the fast path and disables lockless freelists. */ /* * We could simply use migrate_disable()/enable() but as long as it's a * function call even on !PREEMPT_RT, use inline preempt_disable() there. */ #ifndef CONFIG_PREEMPT_RT #define slub_get_cpu_ptr(var) get_cpu_ptr(var) #define slub_put_cpu_ptr(var) put_cpu_ptr(var) #define USE_LOCKLESS_FAST_PATH() (true) #else #define slub_get_cpu_ptr(var) \ ({ \ migrate_disable(); \ this_cpu_ptr(var); \ }) #define slub_put_cpu_ptr(var) \ do { \ (void)(var); \ migrate_enable(); \ } while (0) #define USE_LOCKLESS_FAST_PATH() (false) #endif #ifndef CONFIG_SLUB_TINY #define __fastpath_inline __always_inline #else #define __fastpath_inline #endif #ifdef CONFIG_SLUB_DEBUG #ifdef CONFIG_SLUB_DEBUG_ON DEFINE_STATIC_KEY_TRUE(slub_debug_enabled); #else DEFINE_STATIC_KEY_FALSE(slub_debug_enabled); #endif #endif /* CONFIG_SLUB_DEBUG */ /* Structure holding parameters for get_partial() call chain */ struct partial_context { gfp_t flags; unsigned int orig_size; void *object; }; static inline bool kmem_cache_debug(struct kmem_cache *s) { return kmem_cache_debug_flags(s, SLAB_DEBUG_FLAGS); } static inline bool slub_debug_orig_size(struct kmem_cache *s) { return (kmem_cache_debug_flags(s, SLAB_STORE_USER) && (s->flags & SLAB_KMALLOC)); } void *fixup_red_left(struct kmem_cache *s, void *p) { if (kmem_cache_debug_flags(s, SLAB_RED_ZONE)) p += s->red_left_pad; return p; } static inline bool kmem_cache_has_cpu_partial(struct kmem_cache *s) { #ifdef CONFIG_SLUB_CPU_PARTIAL return !kmem_cache_debug(s); #else return false; #endif } /* * Issues still to be resolved: * * - Support PAGE_ALLOC_DEBUG. Should be easy to do. * * - Variable sizing of the per node arrays */ /* Enable to log cmpxchg failures */ #undef SLUB_DEBUG_CMPXCHG #ifndef CONFIG_SLUB_TINY /* * Minimum number of partial slabs. These will be left on the partial * lists even if they are empty. kmem_cache_shrink may reclaim them. */ #define MIN_PARTIAL 5 /* * Maximum number of desirable partial slabs. * The existence of more partial slabs makes kmem_cache_shrink * sort the partial list by the number of objects in use. */ #define MAX_PARTIAL 10 #else #define MIN_PARTIAL 0 #define MAX_PARTIAL 0 #endif #define DEBUG_DEFAULT_FLAGS (SLAB_CONSISTENCY_CHECKS | SLAB_RED_ZONE | \ SLAB_POISON | SLAB_STORE_USER) /* * These debug flags cannot use CMPXCHG because there might be consistency * issues when checking or reading debug information */ #define SLAB_NO_CMPXCHG (SLAB_CONSISTENCY_CHECKS | SLAB_STORE_USER | \ SLAB_TRACE) /* * Debugging flags that require metadata to be stored in the slab. These get * disabled when slab_debug=O is used and a cache's min order increases with * metadata. */ #define DEBUG_METADATA_FLAGS (SLAB_RED_ZONE | SLAB_POISON | SLAB_STORE_USER) #define OO_SHIFT 16 #define OO_MASK ((1 << OO_SHIFT) - 1) #define MAX_OBJS_PER_PAGE 32767 /* since slab.objects is u15 */ /* Internal SLUB flags */ /* Poison object */ #define __OBJECT_POISON __SLAB_FLAG_BIT(_SLAB_OBJECT_POISON) /* Use cmpxchg_double */ #ifdef system_has_freelist_aba #define __CMPXCHG_DOUBLE __SLAB_FLAG_BIT(_SLAB_CMPXCHG_DOUBLE) #else #define __CMPXCHG_DOUBLE __SLAB_FLAG_UNUSED #endif /* * Tracking user of a slab. */ #define TRACK_ADDRS_COUNT 16 struct track { unsigned long addr; /* Called from address */ #ifdef CONFIG_STACKDEPOT depot_stack_handle_t handle; #endif int cpu; /* Was running on cpu */ int pid; /* Pid context */ unsigned long when; /* When did the operation occur */ }; enum track_item { TRACK_ALLOC, TRACK_FREE }; #ifdef SLAB_SUPPORTS_SYSFS static int sysfs_slab_add(struct kmem_cache *); static int sysfs_slab_alias(struct kmem_cache *, const char *); #else static inline int sysfs_slab_add(struct kmem_cache *s) { return 0; } static inline int sysfs_slab_alias(struct kmem_cache *s, const char *p) { return 0; } #endif #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_SLUB_DEBUG) static void debugfs_slab_add(struct kmem_cache *); #else static inline void debugfs_slab_add(struct kmem_cache *s) { } #endif enum stat_item { ALLOC_FASTPATH, /* Allocation from cpu slab */ ALLOC_SLOWPATH, /* Allocation by getting a new cpu slab */ FREE_FASTPATH, /* Free to cpu slab */ FREE_SLOWPATH, /* Freeing not to cpu slab */ FREE_FROZEN, /* Freeing to frozen slab */ FREE_ADD_PARTIAL, /* Freeing moves slab to partial list */ FREE_REMOVE_PARTIAL, /* Freeing removes last object */ ALLOC_FROM_PARTIAL, /* Cpu slab acquired from node partial list */ ALLOC_SLAB, /* Cpu slab acquired from page allocator */ ALLOC_REFILL, /* Refill cpu slab from slab freelist */ ALLOC_NODE_MISMATCH, /* Switching cpu slab */ FREE_SLAB, /* Slab freed to the page allocator */ CPUSLAB_FLUSH, /* Abandoning of the cpu slab */ DEACTIVATE_FULL, /* Cpu slab was full when deactivated */ DEACTIVATE_EMPTY, /* Cpu slab was empty when deactivated */ DEACTIVATE_TO_HEAD, /* Cpu slab was moved to the head of partials */ DEACTIVATE_TO_TAIL, /* Cpu slab was moved to the tail of partials */ DEACTIVATE_REMOTE_FREES,/* Slab contained remotely freed objects */ DEACTIVATE_BYPASS, /* Implicit deactivation */ ORDER_FALLBACK, /* Number of times fallback was necessary */ CMPXCHG_DOUBLE_CPU_FAIL,/* Failures of this_cpu_cmpxchg_double */ CMPXCHG_DOUBLE_FAIL, /* Failures of slab freelist update */ CPU_PARTIAL_ALLOC, /* Used cpu partial on alloc */ CPU_PARTIAL_FREE, /* Refill cpu partial on free */ CPU_PARTIAL_NODE, /* Refill cpu partial from node partial */ CPU_PARTIAL_DRAIN, /* Drain cpu partial to node partial */ NR_SLUB_STAT_ITEMS }; #ifndef CONFIG_SLUB_TINY /* * When changing the layout, make sure freelist and tid are still compatible * with this_cpu_cmpxchg_double() alignment requirements. */ struct kmem_cache_cpu { union { struct { void **freelist; /* Pointer to next available object */ unsigned long tid; /* Globally unique transaction id */ }; freelist_aba_t freelist_tid; }; struct slab *slab; /* The slab from which we are allocating */ #ifdef CONFIG_SLUB_CPU_PARTIAL struct slab *partial; /* Partially allocated slabs */ #endif local_lock_t lock; /* Protects the fields above */ #ifdef CONFIG_SLUB_STATS unsigned int stat[NR_SLUB_STAT_ITEMS]; #endif }; #endif /* CONFIG_SLUB_TINY */ static inline void stat(const struct kmem_cache *s, enum stat_item si) { #ifdef CONFIG_SLUB_STATS /* * The rmw is racy on a preemptible kernel but this is acceptable, so * avoid this_cpu_add()'s irq-disable overhead. */ raw_cpu_inc(s->cpu_slab->stat[si]); #endif } static inline void stat_add(const struct kmem_cache *s, enum stat_item si, int v) { #ifdef CONFIG_SLUB_STATS raw_cpu_add(s->cpu_slab->stat[si], v); #endif } /* * The slab lists for all objects. */ struct kmem_cache_node { spinlock_t list_lock; unsigned long nr_partial; struct list_head partial; #ifdef CONFIG_SLUB_DEBUG atomic_long_t nr_slabs; atomic_long_t total_objects; struct list_head full; #endif }; static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node) { return s->node[node]; } /* * Iterator over all nodes. The body will be executed for each node that has * a kmem_cache_node structure allocated (which is true for all online nodes) */ #define for_each_kmem_cache_node(__s, __node, __n) \ for (__node = 0; __node < nr_node_ids; __node++) \ if ((__n = get_node(__s, __node))) /* * Tracks for which NUMA nodes we have kmem_cache_nodes allocated. * Corresponds to node_state[N_NORMAL_MEMORY], but can temporarily * differ during memory hotplug/hotremove operations. * Protected by slab_mutex. */ static nodemask_t slab_nodes; #ifndef CONFIG_SLUB_TINY /* * Workqueue used for flush_cpu_slab(). */ static struct workqueue_struct *flushwq; #endif /******************************************************************** * Core slab cache functions *******************************************************************/ /* * freeptr_t represents a SLUB freelist pointer, which might be encoded * and not dereferenceable if CONFIG_SLAB_FREELIST_HARDENED is enabled. */ typedef struct { unsigned long v; } freeptr_t; /* * Returns freelist pointer (ptr). With hardening, this is obfuscated * with an XOR of the address where the pointer is held and a per-cache * random number. */ static inline freeptr_t freelist_ptr_encode(const struct kmem_cache *s, void *ptr, unsigned long ptr_addr) { unsigned long encoded; #ifdef CONFIG_SLAB_FREELIST_HARDENED encoded = (unsigned long)ptr ^ s->random ^ swab(ptr_addr); #else encoded = (unsigned long)ptr; #endif return (freeptr_t){.v = encoded}; } static inline void *freelist_ptr_decode(const struct kmem_cache *s, freeptr_t ptr, unsigned long ptr_addr) { void *decoded; #ifdef CONFIG_SLAB_FREELIST_HARDENED decoded = (void *)(ptr.v ^ s->random ^ swab(ptr_addr)); #else decoded = (void *)ptr.v; #endif return decoded; } static inline void *get_freepointer(struct kmem_cache *s, void *object) { unsigned long ptr_addr; freeptr_t p; object = kasan_reset_tag(object); ptr_addr = (unsigned long)object + s->offset; p = *(freeptr_t *)(ptr_addr); return freelist_ptr_decode(s, p, ptr_addr); } #ifndef CONFIG_SLUB_TINY static void prefetch_freepointer(const struct kmem_cache *s, void *object) { prefetchw(object + s->offset); } #endif /* * When running under KMSAN, get_freepointer_safe() may return an uninitialized * pointer value in the case the current thread loses the race for the next * memory chunk in the freelist. In that case this_cpu_cmpxchg_double() in * slab_alloc_node() will fail, so the uninitialized value won't be used, but * KMSAN will still check all arguments of cmpxchg because of imperfect * handling of inline assembly. * To work around this problem, we apply __no_kmsan_checks to ensure that * get_freepointer_safe() returns initialized memory. */ __no_kmsan_checks static inline void *get_freepointer_safe(struct kmem_cache *s, void *object) { unsigned long freepointer_addr; freeptr_t p; if (!debug_pagealloc_enabled_static()) return get_freepointer(s, object); object = kasan_reset_tag(object); freepointer_addr = (unsigned long)object + s->offset; copy_from_kernel_nofault(&p, (freeptr_t *)freepointer_addr, sizeof(p)); return freelist_ptr_decode(s, p, freepointer_addr); } static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp) { unsigned long freeptr_addr = (unsigned long)object + s->offset; #ifdef CONFIG_SLAB_FREELIST_HARDENED BUG_ON(object == fp); /* naive detection of double free or corruption */ #endif freeptr_addr = (unsigned long)kasan_reset_tag((void *)freeptr_addr); *(freeptr_t *)freeptr_addr = freelist_ptr_encode(s, fp, freeptr_addr); } /* Loop over all objects in a slab */ #define for_each_object(__p, __s, __addr, __objects) \ for (__p = fixup_red_left(__s, __addr); \ __p < (__addr) + (__objects) * (__s)->size; \ __p += (__s)->size) static inline unsigned int order_objects(unsigned int order, unsigned int size) { return ((unsigned int)PAGE_SIZE << order) / size; } static inline struct kmem_cache_order_objects oo_make(unsigned int order, unsigned int size) { struct kmem_cache_order_objects x = { (order << OO_SHIFT) + order_objects(order, size) }; return x; } static inline unsigned int oo_order(struct kmem_cache_order_objects x) { return x.x >> OO_SHIFT; } static inline unsigned int oo_objects(struct kmem_cache_order_objects x) { return x.x & OO_MASK; } #ifdef CONFIG_SLUB_CPU_PARTIAL static void slub_set_cpu_partial(struct kmem_cache *s, unsigned int nr_objects) { unsigned int nr_slabs; s->cpu_partial = nr_objects; /* * We take the number of objects but actually limit the number of * slabs on the per cpu partial list, in order to limit excessive * growth of the list. For simplicity we assume that the slabs will * be half-full. */ nr_slabs = DIV_ROUND_UP(nr_objects * 2, oo_objects(s->oo)); s->cpu_partial_slabs = nr_slabs; } #else static inline void slub_set_cpu_partial(struct kmem_cache *s, unsigned int nr_objects) { } #endif /* CONFIG_SLUB_CPU_PARTIAL */ /* * Per slab locking using the pagelock */ static __always_inline void slab_lock(struct slab *slab) { struct page *page = slab_page(slab); VM_BUG_ON_PAGE(PageTail(page), page); bit_spin_lock(PG_locked, &page->flags); } static __always_inline void slab_unlock(struct slab *slab) { struct page *page = slab_page(slab); VM_BUG_ON_PAGE(PageTail(page), page); bit_spin_unlock(PG_locked, &page->flags); } static inline bool __update_freelist_fast(struct slab *slab, void *freelist_old, unsigned long counters_old, void *freelist_new, unsigned long counters_new) { #ifdef system_has_freelist_aba freelist_aba_t old = { .freelist = freelist_old, .counter = counters_old }; freelist_aba_t new = { .freelist = freelist_new, .counter = counters_new }; return try_cmpxchg_freelist(&slab->freelist_counter.full, &old.full, new.full); #else return false; #endif } static inline bool __update_freelist_slow(struct slab *slab, void *freelist_old, unsigned long counters_old, void *freelist_new, unsigned long counters_new) { bool ret = false; slab_lock(slab); if (slab->freelist == freelist_old && slab->counters == counters_old) { slab->freelist = freelist_new; slab->counters = counters_new; ret = true; } slab_unlock(slab); return ret; } /* * Interrupts must be disabled (for the fallback code to work right), typically * by an _irqsave() lock variant. On PREEMPT_RT the preempt_disable(), which is * part of bit_spin_lock(), is sufficient because the policy is not to allow any * allocation/ free operation in hardirq context. Therefore nothing can * interrupt the operation. */ static inline bool __slab_update_freelist(struct kmem_cache *s, struct slab *slab, void *freelist_old, unsigned long counters_old, void *freelist_new, unsigned long counters_new, const char *n) { bool ret; if (USE_LOCKLESS_FAST_PATH()) lockdep_assert_irqs_disabled(); if (s->flags & __CMPXCHG_DOUBLE) { ret = __update_freelist_fast(slab, freelist_old, counters_old, freelist_new, counters_new); } else { ret = __update_freelist_slow(slab, freelist_old, counters_old, freelist_new, counters_new); } if (likely(ret)) return true; cpu_relax(); stat(s, CMPXCHG_DOUBLE_FAIL); #ifdef SLUB_DEBUG_CMPXCHG pr_info("%s %s: cmpxchg double redo ", n, s->name); #endif return false; } static inline bool slab_update_freelist(struct kmem_cache *s, struct slab *slab, void *freelist_old, unsigned long counters_old, void *freelist_new, unsigned long counters_new, const char *n) { bool ret; if (s->flags & __CMPXCHG_DOUBLE) { ret = __update_freelist_fast(slab, freelist_old, counters_old, freelist_new, counters_new); } else { unsigned long flags; local_irq_save(flags); ret = __update_freelist_slow(slab, freelist_old, counters_old, freelist_new, counters_new); local_irq_restore(flags); } if (likely(ret)) return true; cpu_relax(); stat(s, CMPXCHG_DOUBLE_FAIL); #ifdef SLUB_DEBUG_CMPXCHG pr_info("%s %s: cmpxchg double redo ", n, s->name); #endif return false; } #ifdef CONFIG_SLUB_DEBUG static unsigned long object_map[BITS_TO_LONGS(MAX_OBJS_PER_PAGE)]; static DEFINE_SPINLOCK(object_map_lock); static void __fill_map(unsigned long *obj_map, struct kmem_cache *s, struct slab *slab) { void *addr = slab_address(slab); void *p; bitmap_zero(obj_map, slab->objects); for (p = slab->freelist; p; p = get_freepointer(s, p)) set_bit(__obj_to_index(s, addr, p), obj_map); } #if IS_ENABLED(CONFIG_KUNIT) static bool slab_add_kunit_errors(void) { struct kunit_resource *resource; if (!kunit_get_current_test()) return false; resource = kunit_find_named_resource(current->kunit_test, "slab_errors"); if (!resource) return false; (*(int *)resource->data)++; kunit_put_resource(resource); return true; } #else static inline bool slab_add_kunit_errors(void) { return false; } #endif static inline unsigned int size_from_object(struct kmem_cache *s) { if (s->flags & SLAB_RED_ZONE) return s->size - s->red_left_pad; return s->size; } static inline void *restore_red_left(struct kmem_cache *s, void *p) { if (s->flags & SLAB_RED_ZONE) p -= s->red_left_pad; return p; } /* * Debug settings: */ #if defined(CONFIG_SLUB_DEBUG_ON) static slab_flags_t slub_debug = DEBUG_DEFAULT_FLAGS; #else static slab_flags_t slub_debug; #endif static char *slub_debug_string; static int disable_higher_order_debug; /* * slub is about to manipulate internal object metadata. This memory lies * outside the range of the allocated object, so accessing it would normally * be reported by kasan as a bounds error. metadata_access_enable() is used * to tell kasan that these accesses are OK. */ static inline void metadata_access_enable(void) { kasan_disable_current(); } static inline void metadata_access_disable(void) { kasan_enable_current(); } /* * Object debugging */ /* Verify that a pointer has an address that is valid within a slab page */ static inline int check_valid_pointer(struct kmem_cache *s, struct slab *slab, void *object) { void *base; if (!object) return 1; base = slab_address(slab); object = kasan_reset_tag(object); object = restore_red_left(s, object); if (object < base || object >= base + slab->objects * s->size || (object - base) % s->size) { return 0; } return 1; } static void print_section(char *level, char *text, u8 *addr, unsigned int length) { metadata_access_enable(); print_hex_dump(level, text, DUMP_PREFIX_ADDRESS, 16, 1, kasan_reset_tag((void *)addr), length, 1); metadata_access_disable(); } /* * See comment in calculate_sizes(). */ static inline bool freeptr_outside_object(struct kmem_cache *s) { return s->offset >= s->inuse; } /* * Return offset of the end of info block which is inuse + free pointer if * not overlapping with object. */ static inline unsigned int get_info_end(struct kmem_cache *s) { if (freeptr_outside_object(s)) return s->inuse + sizeof(void *); else return s->inuse; } static struct track *get_track(struct kmem_cache *s, void *object, enum track_item alloc) { struct track *p; p = object + get_info_end(s); return kasan_reset_tag(p + alloc); } #ifdef CONFIG_STACKDEPOT static noinline depot_stack_handle_t set_track_prepare(void) { depot_stack_handle_t handle; unsigned long entries[TRACK_ADDRS_COUNT]; unsigned int nr_entries; nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 3); handle = stack_depot_save(entries, nr_entries, GFP_NOWAIT); return handle; } #else static inline depot_stack_handle_t set_track_prepare(void) { return 0; } #endif static void set_track_update(struct kmem_cache *s, void *object, enum track_item alloc, unsigned long addr, depot_stack_handle_t handle) { struct track *p = get_track(s, object, alloc); #ifdef CONFIG_STACKDEPOT p->handle = handle; #endif p->addr = addr; p->cpu = smp_processor_id(); p->pid = current->pid; p->when = jiffies; } static __always_inline void set_track(struct kmem_cache *s, void *object, enum track_item alloc, unsigned long addr) { depot_stack_handle_t handle = set_track_prepare(); set_track_update(s, object, alloc, addr, handle); } static void init_tracking(struct kmem_cache *s, void *object) { struct track *p; if (!(s->flags & SLAB_STORE_USER)) return; p = get_track(s, object, TRACK_ALLOC); memset(p, 0, 2*sizeof(struct track)); } static void print_track(const char *s, struct track *t, unsigned long pr_time) { depot_stack_handle_t handle __maybe_unused; if (!t->addr) return; pr_err("%s in %pS age=%lu cpu=%u pid=%d\n", s, (void *)t->addr, pr_time - t->when, t->cpu, t->pid); #ifdef CONFIG_STACKDEPOT handle = READ_ONCE(t->handle); if (handle) stack_depot_print(handle); else pr_err("object allocation/free stack trace missing\n"); #endif } void print_tracking(struct kmem_cache *s, void *object) { unsigned long pr_time = jiffies; if (!(s->flags & SLAB_STORE_USER)) return; print_track("Allocated", get_track(s, object, TRACK_ALLOC), pr_time); print_track("Freed", get_track(s, object, TRACK_FREE), pr_time); } static void print_slab_info(const struct slab *slab) { struct folio *folio = (struct folio *)slab_folio(slab); pr_err("Slab 0x%p objects=%u used=%u fp=0x%p flags=%pGp\n", slab, slab->objects, slab->inuse, slab->freelist, folio_flags(folio, 0)); } /* * kmalloc caches has fixed sizes (mostly power of 2), and kmalloc() API * family will round up the real request size to these fixed ones, so * there could be an extra area than what is requested. Save the original * request size in the meta data area, for better debug and sanity check. */ static inline void set_orig_size(struct kmem_cache *s, void *object, unsigned int orig_size) { void *p = kasan_reset_tag(object); unsigned int kasan_meta_size; if (!slub_debug_orig_size(s)) return; /* * KASAN can save its free meta data inside of the object at offset 0. * If this meta data size is larger than 'orig_size', it will overlap * the data redzone in [orig_size+1, object_size]. Thus, we adjust * 'orig_size' to be as at least as big as KASAN's meta data. */ kasan_meta_size = kasan_metadata_size(s, true); if (kasan_meta_size > orig_size) orig_size = kasan_meta_size; p += get_info_end(s); p += sizeof(struct track) * 2; *(unsigned int *)p = orig_size; } static inline unsigned int get_orig_size(struct kmem_cache *s, void *object) { void *p = kasan_reset_tag(object); if (!slub_debug_orig_size(s)) return s->object_size; p += get_info_end(s); p += sizeof(struct track) * 2; return *(unsigned int *)p; } void skip_orig_size_check(struct kmem_cache *s, const void *object) { set_orig_size(s, (void *)object, s->object_size); } static void slab_bug(struct kmem_cache *s, char *fmt, ...) { struct va_format vaf; va_list args; va_start(args, fmt); vaf.fmt = fmt; vaf.va = &args; pr_err("=============================================================================\n"); pr_err("BUG %s (%s): %pV\n", s->name, print_tainted(), &vaf); pr_err("-----------------------------------------------------------------------------\n\n"); va_end(args); } __printf(2, 3) static void slab_fix(struct kmem_cache *s, char *fmt, ...) { struct va_format vaf; va_list args; if (slab_add_kunit_errors()) return; va_start(args, fmt); vaf.fmt = fmt; vaf.va = &args; pr_err("FIX %s: %pV\n", s->name, &vaf); va_end(args); } static void print_trailer(struct kmem_cache *s, struct slab *slab, u8 *p) { unsigned int off; /* Offset of last byte */ u8 *addr = slab_address(slab); print_tracking(s, p); print_slab_info(slab); pr_err("Object 0x%p @offset=%tu fp=0x%p\n\n", p, p - addr, get_freepointer(s, p)); if (s->flags & SLAB_RED_ZONE) print_section(KERN_ERR, "Redzone ", p - s->red_left_pad, s->red_left_pad); else if (p > addr + 16) print_section(KERN_ERR, "Bytes b4 ", p - 16, 16); print_section(KERN_ERR, "Object ", p, min_t(unsigned int, s->object_size, PAGE_SIZE)); if (s->flags & SLAB_RED_ZONE) print_section(KERN_ERR, "Redzone ", p + s->object_size, s->inuse - s->object_size); off = get_info_end(s); if (s->flags & SLAB_STORE_USER) off += 2 * sizeof(struct track); if (slub_debug_orig_size(s)) off += sizeof(unsigned int); off += kasan_metadata_size(s, false); if (off != size_from_object(s)) /* Beginning of the filler is the free pointer */ print_section(KERN_ERR, "Padding ", p + off, size_from_object(s) - off); dump_stack(); } static void object_err(struct kmem_cache *s, struct slab *slab, u8 *object, char *reason) { if (slab_add_kunit_errors()) return; slab_bug(s, "%s", reason); print_trailer(s, slab, object); add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); } static bool freelist_corrupted(struct kmem_cache *s, struct slab *slab, void **freelist, void *nextfree) { if ((s->flags & SLAB_CONSISTENCY_CHECKS) && !check_valid_pointer(s, slab, nextfree) && freelist) { object_err(s, slab, *freelist, "Freechain corrupt"); *freelist = NULL; slab_fix(s, "Isolate corrupted freechain"); return true; } return false; } static __printf(3, 4) void slab_err(struct kmem_cache *s, struct slab *slab, const char *fmt, ...) { va_list args; char buf[100]; if (slab_add_kunit_errors()) return; va_start(args, fmt); vsnprintf(buf, sizeof(buf), fmt, args); va_end(args); slab_bug(s, "%s", buf); print_slab_info(slab); dump_stack(); add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); } static void init_object(struct kmem_cache *s, void *object, u8 val) { u8 *p = kasan_reset_tag(object); unsigned int poison_size = s->object_size; if (s->flags & SLAB_RED_ZONE) { memset(p - s->red_left_pad, val, s->red_left_pad); if (slub_debug_orig_size(s) && val == SLUB_RED_ACTIVE) { /* * Redzone the extra allocated space by kmalloc than * requested, and the poison size will be limited to * the original request size accordingly. */ poison_size = get_orig_size(s, object); } } if (s->flags & __OBJECT_POISON) { memset(p, POISON_FREE, poison_size - 1); p[poison_size - 1] = POISON_END; } if (s->flags & SLAB_RED_ZONE) memset(p + poison_size, val, s->inuse - poison_size); } static void restore_bytes(struct kmem_cache *s, char *message, u8 data, void *from, void *to) { slab_fix(s, "Restoring %s 0x%p-0x%p=0x%x", message, from, to - 1, data); memset(from, data, to - from); } static int check_bytes_and_report(struct kmem_cache *s, struct slab *slab, u8 *object, char *what, u8 *start, unsigned int value, unsigned int bytes) { u8 *fault; u8 *end; u8 *addr = slab_address(slab); metadata_access_enable(); fault = memchr_inv(kasan_reset_tag(start), value, bytes); metadata_access_disable(); if (!fault) return 1; end = start + bytes; while (end > fault && end[-1] == value) end--; if (slab_add_kunit_errors()) goto skip_bug_print; slab_bug(s, "%s overwritten", what); pr_err("0x%p-0x%p @offset=%tu. First byte 0x%x instead of 0x%x\n", fault, end - 1, fault - addr, fault[0], value); print_trailer(s, slab, object); add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); skip_bug_print: restore_bytes(s, what, value, fault, end); return 0; } /* * Object layout: * * object address * Bytes of the object to be managed. * If the freepointer may overlay the object then the free * pointer is at the middle of the object. * * Poisoning uses 0x6b (POISON_FREE) and the last byte is * 0xa5 (POISON_END) * * object + s->object_size * Padding to reach word boundary. This is also used for Redzoning. * Padding is extended by another word if Redzoning is enabled and * object_size == inuse. * * We fill with 0xbb (RED_INACTIVE) for inactive objects and with * 0xcc (RED_ACTIVE) for objects in use. * * object + s->inuse * Meta data starts here. * * A. Free pointer (if we cannot overwrite object on free) * B. Tracking data for SLAB_STORE_USER * C. Original request size for kmalloc object (SLAB_STORE_USER enabled) * D. Padding to reach required alignment boundary or at minimum * one word if debugging is on to be able to detect writes * before the word boundary. * * Padding is done using 0x5a (POISON_INUSE) * * object + s->size * Nothing is used beyond s->size. * * If slabcaches are merged then the object_size and inuse boundaries are mostly * ignored. And therefore no slab options that rely on these boundaries * may be used with merged slabcaches. */ static int check_pad_bytes(struct kmem_cache *s, struct slab *slab, u8 *p) { unsigned long off = get_info_end(s); /* The end of info */ if (s->flags & SLAB_STORE_USER) { /* We also have user information there */ off += 2 * sizeof(struct track); if (s->flags & SLAB_KMALLOC) off += sizeof(unsigned int); } off += kasan_metadata_size(s, false); if (size_from_object(s) == off) return 1; return check_bytes_and_report(s, slab, p, "Object padding", p + off, POISON_INUSE, size_from_object(s) - off); } /* Check the pad bytes at the end of a slab page */ static void slab_pad_check(struct kmem_cache *s, struct slab *slab) { u8 *start; u8 *fault; u8 *end; u8 *pad; int length; int remainder; if (!(s->flags & SLAB_POISON)) return; start = slab_address(slab); length = slab_size(slab); end = start + length; remainder = length % s->size; if (!remainder) return; pad = end - remainder; metadata_access_enable(); fault = memchr_inv(kasan_reset_tag(pad), POISON_INUSE, remainder); metadata_access_disable(); if (!fault) return; while (end > fault && end[-1] == POISON_INUSE) end--; slab_err(s, slab, "Padding overwritten. 0x%p-0x%p @offset=%tu", fault, end - 1, fault - start); print_section(KERN_ERR, "Padding ", pad, remainder); restore_bytes(s, "slab padding", POISON_INUSE, fault, end); } static int check_object(struct kmem_cache *s, struct slab *slab, void *object, u8 val) { u8 *p = object; u8 *endobject = object + s->object_size; unsigned int orig_size, kasan_meta_size; if (s->flags & SLAB_RED_ZONE) { if (!check_bytes_and_report(s, slab, object, "Left Redzone", object - s->red_left_pad, val, s->red_left_pad)) return 0; if (!check_bytes_and_report(s, slab, object, "Right Redzone", endobject, val, s->inuse - s->object_size)) return 0; if (slub_debug_orig_size(s) && val == SLUB_RED_ACTIVE) { orig_size = get_orig_size(s, object); if (s->object_size > orig_size && !check_bytes_and_report(s, slab, object, "kmalloc Redzone", p + orig_size, val, s->object_size - orig_size)) { return 0; } } } else { if ((s->flags & SLAB_POISON) && s->object_size < s->inuse) { check_bytes_and_report(s, slab, p, "Alignment padding", endobject, POISON_INUSE, s->inuse - s->object_size); } } if (s->flags & SLAB_POISON) { if (val != SLUB_RED_ACTIVE && (s->flags & __OBJECT_POISON)) { /* * KASAN can save its free meta data inside of the * object at offset 0. Thus, skip checking the part of * the redzone that overlaps with the meta data. */ kasan_meta_size = kasan_metadata_size(s, true); if (kasan_meta_size < s->object_size - 1 && !check_bytes_and_report(s, slab, p, "Poison", p + kasan_meta_size, POISON_FREE, s->object_size - kasan_meta_size - 1)) return 0; if (kasan_meta_size < s->object_size && !check_bytes_and_report(s, slab, p, "End Poison", p + s->object_size - 1, POISON_END, 1)) return 0; } /* * check_pad_bytes cleans up on its own. */ check_pad_bytes(s, slab, p); } if (!freeptr_outside_object(s) && val == SLUB_RED_ACTIVE) /* * Object and freepointer overlap. Cannot check * freepointer while object is allocated. */ return 1; /* Check free pointer validity */ if (!check_valid_pointer(s, slab, get_freepointer(s, p))) { object_err(s, slab, p, "Freepointer corrupt"); /* * No choice but to zap it and thus lose the remainder * of the free objects in this slab. May cause * another error because the object count is now wrong. */ set_freepointer(s, p, NULL); return 0; } return 1; } static int check_slab(struct kmem_cache *s, struct slab *slab) { int maxobj; if (!folio_test_slab(slab_folio(slab))) { slab_err(s, slab, "Not a valid slab page"); return 0; } maxobj = order_objects(slab_order(slab), s->size); if (slab->objects > maxobj) { slab_err(s, slab, "objects %u > max %u", slab->objects, maxobj); return 0; } if (slab->inuse > slab->objects) { slab_err(s, slab, "inuse %u > max %u", slab->inuse, slab->objects); return 0; } /* Slab_pad_check fixes things up after itself */ slab_pad_check(s, slab); return 1; } /* * Determine if a certain object in a slab is on the freelist. Must hold the * slab lock to guarantee that the chains are in a consistent state. */ static int on_freelist(struct kmem_cache *s, struct slab *slab, void *search) { int nr = 0; void *fp; void *object = NULL; int max_objects; fp = slab->freelist; while (fp && nr <= slab->objects) { if (fp == search) return 1; if (!check_valid_pointer(s, slab, fp)) { if (object) { object_err(s, slab, object, "Freechain corrupt"); set_freepointer(s, object, NULL); } else { slab_err(s, slab, "Freepointer corrupt"); slab->freelist = NULL; slab->inuse = slab->objects; slab_fix(s, "Freelist cleared"); return 0; } break; } object = fp; fp = get_freepointer(s, object); nr++; } max_objects = order_objects(slab_order(slab), s->size); if (max_objects > MAX_OBJS_PER_PAGE) max_objects = MAX_OBJS_PER_PAGE; if (slab->objects != max_objects) { slab_err(s, slab, "Wrong number of objects. Found %d but should be %d", slab->objects, max_objects); slab->objects = max_objects; slab_fix(s, "Number of objects adjusted"); } if (slab->inuse != slab->objects - nr) { slab_err(s, slab, "Wrong object count. Counter is %d but counted were %d", slab->inuse, slab->objects - nr); slab->inuse = slab->objects - nr; slab_fix(s, "Object count adjusted"); } return search == NULL; } static void trace(struct kmem_cache *s, struct slab *slab, void *object, int alloc) { if (s->flags & SLAB_TRACE) { pr_info("TRACE %s %s 0x%p inuse=%d fp=0x%p\n", s->name, alloc ? "alloc" : "free", object, slab->inuse, slab->freelist); if (!alloc) print_section(KERN_INFO, "Object ", (void *)object, s->object_size); dump_stack(); } } /* * Tracking of fully allocated slabs for debugging purposes. */ static void add_full(struct kmem_cache *s, struct kmem_cache_node *n, struct slab *slab) { if (!(s->flags & SLAB_STORE_USER)) return; lockdep_assert_held(&n->list_lock); list_add(&slab->slab_list, &n->full); } static void remove_full(struct kmem_cache *s, struct kmem_cache_node *n, struct slab *slab) { if (!(s->flags & SLAB_STORE_USER)) return; lockdep_assert_held(&n->list_lock); list_del(&slab->slab_list); } static inline unsigned long node_nr_slabs(struct kmem_cache_node *n) { return atomic_long_read(&n->nr_slabs); } static inline void inc_slabs_node(struct kmem_cache *s, int node, int objects) { struct kmem_cache_node *n = get_node(s, node); atomic_long_inc(&n->nr_slabs); atomic_long_add(objects, &n->total_objects); } static inline void dec_slabs_node(struct kmem_cache *s, int node, int objects) { struct kmem_cache_node *n = get_node(s, node); atomic_long_dec(&n->nr_slabs); atomic_long_sub(objects, &n->total_objects); } /* Object debug checks for alloc/free paths */ static void setup_object_debug(struct kmem_cache *s, void *object) { if (!kmem_cache_debug_flags(s, SLAB_STORE_USER|SLAB_RED_ZONE|__OBJECT_POISON)) return; init_object(s, object, SLUB_RED_INACTIVE); init_tracking(s, object); } static void setup_slab_debug(struct kmem_cache *s, struct slab *slab, void *addr) { if (!kmem_cache_debug_flags(s, SLAB_POISON)) return; metadata_access_enable(); memset(kasan_reset_tag(addr), POISON_INUSE, slab_size(slab)); metadata_access_disable(); } static inline int alloc_consistency_checks(struct kmem_cache *s, struct slab *slab, void *object) { if (!check_slab(s, slab)) return 0; if (!check_valid_pointer(s, slab, object)) { object_err(s, slab, object, "Freelist Pointer check fails"); return 0; } if (!check_object(s, slab, object, SLUB_RED_INACTIVE)) return 0; return 1; } static noinline bool alloc_debug_processing(struct kmem_cache *s, struct slab *slab, void *object, int orig_size) { if (s->flags & SLAB_CONSISTENCY_CHECKS) { if (!alloc_consistency_checks(s, slab, object)) goto bad; } /* Success. Perform special debug activities for allocs */ trace(s, slab, object, 1); set_orig_size(s, object, orig_size); init_object(s, object, SLUB_RED_ACTIVE); return true; bad: if (folio_test_slab(slab_folio(slab))) { /* * If this is a slab page then lets do the best we can * to avoid issues in the future. Marking all objects * as used avoids touching the remaining objects. */ slab_fix(s, "Marking all objects used"); slab->inuse = slab->objects; slab->freelist = NULL; } return false; } static inline int free_consistency_checks(struct kmem_cache *s, struct slab *slab, void *object, unsigned long addr) { if (!check_valid_pointer(s, slab, object)) { slab_err(s, slab, "Invalid object pointer 0x%p", object); return 0; } if (on_freelist(s, slab, object)) { object_err(s, slab, object, "Object already free"); return 0; } if (!check_object(s, slab, object, SLUB_RED_ACTIVE)) return 0; if (unlikely(s != slab->slab_cache)) { if (!folio_test_slab(slab_folio(slab))) { slab_err(s, slab, "Attempt to free object(0x%p) outside of slab", object); } else if (!slab->slab_cache) { pr_err("SLUB : no slab for object 0x%p.\n", object); dump_stack(); } else object_err(s, slab, object, "page slab pointer corrupt."); return 0; } return 1; } /* * Parse a block of slab_debug options. Blocks are delimited by ';' * * @str: start of block * @flags: returns parsed flags, or DEBUG_DEFAULT_FLAGS if none specified * @slabs: return start of list of slabs, or NULL when there's no list * @init: assume this is initial parsing and not per-kmem-create parsing * * returns the start of next block if there's any, or NULL */ static char * parse_slub_debug_flags(char *str, slab_flags_t *flags, char **slabs, bool init) { bool higher_order_disable = false; /* Skip any completely empty blocks */ while (*str && *str == ';') str++; if (*str == ',') { /* * No options but restriction on slabs. This means full * debugging for slabs matching a pattern. */ *flags = DEBUG_DEFAULT_FLAGS; goto check_slabs; } *flags = 0; /* Determine which debug features should be switched on */ for (; *str && *str != ',' && *str != ';'; str++) { switch (tolower(*str)) { case '-': *flags = 0; break; case 'f': *flags |= SLAB_CONSISTENCY_CHECKS; break; case 'z': *flags |= SLAB_RED_ZONE; break; case 'p': *flags |= SLAB_POISON; break; case 'u': *flags |= SLAB_STORE_USER; break; case 't': *flags |= SLAB_TRACE; break; case 'a': *flags |= SLAB_FAILSLAB; break; case 'o': /* * Avoid enabling debugging on caches if its minimum * order would increase as a result. */ higher_order_disable = true; break; default: if (init) pr_err("slab_debug option '%c' unknown. skipped\n", *str); } } check_slabs: if (*str == ',') *slabs = ++str; else *slabs = NULL; /* Skip over the slab list */ while (*str && *str != ';') str++; /* Skip any completely empty blocks */ while (*str && *str == ';') str++; if (init && higher_order_disable) disable_higher_order_debug = 1; if (*str) return str; else return NULL; } static int __init setup_slub_debug(char *str) { slab_flags_t flags; slab_flags_t global_flags; char *saved_str; char *slab_list; bool global_slub_debug_changed = false; bool slab_list_specified = false; global_flags = DEBUG_DEFAULT_FLAGS; if (*str++ != '=' || !*str) /* * No options specified. Switch on full debugging. */ goto out; saved_str = str; while (str) { str = parse_slub_debug_flags(str, &flags, &slab_list, true); if (!slab_list) { global_flags = flags; global_slub_debug_changed = true; } else { slab_list_specified = true; if (flags & SLAB_STORE_USER) stack_depot_request_early_init(); } } /* * For backwards compatibility, a single list of flags with list of * slabs means debugging is only changed for those slabs, so the global * slab_debug should be unchanged (0 or DEBUG_DEFAULT_FLAGS, depending * on CONFIG_SLUB_DEBUG_ON). We can extended that to multiple lists as * long as there is no option specifying flags without a slab list. */ if (slab_list_specified) { if (!global_slub_debug_changed) global_flags = slub_debug; slub_debug_string = saved_str; } out: slub_debug = global_flags; if (slub_debug & SLAB_STORE_USER) stack_depot_request_early_init(); if (slub_debug != 0 || slub_debug_string) static_branch_enable(&slub_debug_enabled); else static_branch_disable(&slub_debug_enabled); if ((static_branch_unlikely(&init_on_alloc) || static_branch_unlikely(&init_on_free)) && (slub_debug & SLAB_POISON)) pr_info("mem auto-init: SLAB_POISON will take precedence over init_on_alloc/init_on_free\n"); return 1; } __setup("slab_debug", setup_slub_debug); __setup_param("slub_debug", slub_debug, setup_slub_debug, 0); /* * kmem_cache_flags - apply debugging options to the cache * @flags: flags to set * @name: name of the cache * * Debug option(s) are applied to @flags. In addition to the debug * option(s), if a slab name (or multiple) is specified i.e. * slab_debug=,, ... * then only the select slabs will receive the debug option(s). */ slab_flags_t kmem_cache_flags(slab_flags_t flags, const char *name) { char *iter; size_t len; char *next_block; slab_flags_t block_flags; slab_flags_t slub_debug_local = slub_debug; if (flags & SLAB_NO_USER_FLAGS) return flags; /* * If the slab cache is for debugging (e.g. kmemleak) then * don't store user (stack trace) information by default, * but let the user enable it via the command line below. */ if (flags & SLAB_NOLEAKTRACE) slub_debug_local &= ~SLAB_STORE_USER; len = strlen(name); next_block = slub_debug_string; /* Go through all blocks of debug options, see if any matches our slab's name */ while (next_block) { next_block = parse_slub_debug_flags(next_block, &block_flags, &iter, false); if (!iter) continue; /* Found a block that has a slab list, search it */ while (*iter) { char *end, *glob; size_t cmplen; end = strchrnul(iter, ','); if (next_block && next_block < end) end = next_block - 1; glob = strnchr(iter, end - iter, '*'); if (glob) cmplen = glob - iter; else cmplen = max_t(size_t, len, (end - iter)); if (!strncmp(name, iter, cmplen)) { flags |= block_flags; return flags; } if (!*end || *end == ';') break; iter = end + 1; } } return flags | slub_debug_local; } #else /* !CONFIG_SLUB_DEBUG */ static inline void setup_object_debug(struct kmem_cache *s, void *object) {} static inline void setup_slab_debug(struct kmem_cache *s, struct slab *slab, void *addr) {} static inline bool alloc_debug_processing(struct kmem_cache *s, struct slab *slab, void *object, int orig_size) { return true; } static inline bool free_debug_processing(struct kmem_cache *s, struct slab *slab, void *head, void *tail, int *bulk_cnt, unsigned long addr, depot_stack_handle_t handle) { return true; } static inline void slab_pad_check(struct kmem_cache *s, struct slab *slab) {} static inline int check_object(struct kmem_cache *s, struct slab *slab, void *object, u8 val) { return 1; } static inline depot_stack_handle_t set_track_prepare(void) { return 0; } static inline void set_track(struct kmem_cache *s, void *object, enum track_item alloc, unsigned long addr) {} static inline void add_full(struct kmem_cache *s, struct kmem_cache_node *n, struct slab *slab) {} static inline void remove_full(struct kmem_cache *s, struct kmem_cache_node *n, struct slab *slab) {} slab_flags_t kmem_cache_flags(slab_flags_t flags, const char *name) { return flags; } #define slub_debug 0 #define disable_higher_order_debug 0 static inline unsigned long node_nr_slabs(struct kmem_cache_node *n) { return 0; } static inline void inc_slabs_node(struct kmem_cache *s, int node, int objects) {} static inline void dec_slabs_node(struct kmem_cache *s, int node, int objects) {} #ifndef CONFIG_SLUB_TINY static bool freelist_corrupted(struct kmem_cache *s, struct slab *slab, void **freelist, void *nextfree) { return false; } #endif #endif /* CONFIG_SLUB_DEBUG */ static inline enum node_stat_item cache_vmstat_idx(struct kmem_cache *s) { return (s->flags & SLAB_RECLAIM_ACCOUNT) ? NR_SLAB_RECLAIMABLE_B : NR_SLAB_UNRECLAIMABLE_B; } #ifdef CONFIG_MEMCG_KMEM static inline void memcg_free_slab_cgroups(struct slab *slab) { kfree(slab_objcgs(slab)); slab->memcg_data = 0; } static inline size_t obj_full_size(struct kmem_cache *s) { /* * For each accounted object there is an extra space which is used * to store obj_cgroup membership. Charge it too. */ return s->size + sizeof(struct obj_cgroup *); } /* * Returns false if the allocation should fail. */ static bool __memcg_slab_pre_alloc_hook(struct kmem_cache *s, struct list_lru *lru, struct obj_cgroup **objcgp, size_t objects, gfp_t flags) { /* * The obtained objcg pointer is safe to use within the current scope, * defined by current task or set_active_memcg() pair. * obj_cgroup_get() is used to get a permanent reference. */ struct obj_cgroup *objcg = current_obj_cgroup(); if (!objcg) return true; if (lru) { int ret; struct mem_cgroup *memcg; memcg = get_mem_cgroup_from_objcg(objcg); ret = memcg_list_lru_alloc(memcg, lru, flags); css_put(&memcg->css); if (ret) return false; } if (obj_cgroup_charge(objcg, flags, objects * obj_full_size(s))) return false; *objcgp = objcg; return true; } /* * Returns false if the allocation should fail. */ static __fastpath_inline bool memcg_slab_pre_alloc_hook(struct kmem_cache *s, struct list_lru *lru, struct obj_cgroup **objcgp, size_t objects, gfp_t flags) { if (!memcg_kmem_online()) return true; if (likely(!(flags & __GFP_ACCOUNT) && !(s->flags & SLAB_ACCOUNT))) return true; return likely(__memcg_slab_pre_alloc_hook(s, lru, objcgp, objects, flags)); } static void __memcg_slab_post_alloc_hook(struct kmem_cache *s, struct obj_cgroup *objcg, gfp_t flags, size_t size, void **p) { struct slab *slab; unsigned long off; size_t i; flags &= gfp_allowed_mask; for (i = 0; i < size; i++) { if (likely(p[i])) { slab = virt_to_slab(p[i]); if (!slab_objcgs(slab) && memcg_alloc_slab_cgroups(slab, s, flags, false)) { obj_cgroup_uncharge(objcg, obj_full_size(s)); continue; } off = obj_to_index(s, slab, p[i]); obj_cgroup_get(objcg); slab_objcgs(slab)[off] = objcg; mod_objcg_state(objcg, slab_pgdat(slab), cache_vmstat_idx(s), obj_full_size(s)); } else { obj_cgroup_uncharge(objcg, obj_full_size(s)); } } } static __fastpath_inline void memcg_slab_post_alloc_hook(struct kmem_cache *s, struct obj_cgroup *objcg, gfp_t flags, size_t size, void **p) { if (likely(!memcg_kmem_online() || !objcg)) return; return __memcg_slab_post_alloc_hook(s, objcg, flags, size, p); } static void __memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab, void **p, int objects, struct obj_cgroup **objcgs) { for (int i = 0; i < objects; i++) { struct obj_cgroup *objcg; unsigned int off; off = obj_to_index(s, slab, p[i]); objcg = objcgs[off]; if (!objcg) continue; objcgs[off] = NULL; obj_cgroup_uncharge(objcg, obj_full_size(s)); mod_objcg_state(objcg, slab_pgdat(slab), cache_vmstat_idx(s), -obj_full_size(s)); obj_cgroup_put(objcg); } } static __fastpath_inline void memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab, void **p, int objects) { struct obj_cgroup **objcgs; if (!memcg_kmem_online()) return; objcgs = slab_objcgs(slab); if (likely(!objcgs)) return; __memcg_slab_free_hook(s, slab, p, objects, objcgs); } static inline void memcg_slab_alloc_error_hook(struct kmem_cache *s, int objects, struct obj_cgroup *objcg) { if (objcg) obj_cgroup_uncharge(objcg, objects * obj_full_size(s)); } #else /* CONFIG_MEMCG_KMEM */ static inline void memcg_free_slab_cgroups(struct slab *slab) { } static inline bool memcg_slab_pre_alloc_hook(struct kmem_cache *s, struct list_lru *lru, struct obj_cgroup **objcgp, size_t objects, gfp_t flags) { return true; } static inline void memcg_slab_post_alloc_hook(struct kmem_cache *s, struct obj_cgroup *objcg, gfp_t flags, size_t size, void **p) { } static inline void memcg_slab_free_hook(struct kmem_cache *s, struct slab *slab, void **p, int objects) { } static inline void memcg_slab_alloc_error_hook(struct kmem_cache *s, int objects, struct obj_cgroup *objcg) { } #endif /* CONFIG_MEMCG_KMEM */ /* * Hooks for other subsystems that check memory allocations. In a typical * production configuration these hooks all should produce no code at all. * * Returns true if freeing of the object can proceed, false if its reuse * was delayed by KASAN quarantine, or it was returned to KFENCE. */ static __always_inline bool slab_free_hook(struct kmem_cache *s, void *x, bool init) { kmemleak_free_recursive(x, s->flags); kmsan_slab_free(s, x); debug_check_no_locks_freed(x, s->object_size); if (!(s->flags & SLAB_DEBUG_OBJECTS)) debug_check_no_obj_freed(x, s->object_size); /* Use KCSAN to help debug racy use-after-free. */ if (!(s->flags & SLAB_TYPESAFE_BY_RCU)) __kcsan_check_access(x, s->object_size, KCSAN_ACCESS_WRITE | KCSAN_ACCESS_ASSERT); if (kfence_free(x)) return false; /* * As memory initialization might be integrated into KASAN, * kasan_slab_free and initialization memset's must be * kept together to avoid discrepancies in behavior. * * The initialization memset's clear the object and the metadata, * but don't touch the SLAB redzone. */ if (unlikely(init)) { int rsize; if (!kasan_has_integrated_init()) memset(kasan_reset_tag(x), 0, s->object_size); rsize = (s->flags & SLAB_RED_ZONE) ? s->red_left_pad : 0; memset((char *)kasan_reset_tag(x) + s->inuse, 0, s->size - s->inuse - rsize); } /* KASAN might put x into memory quarantine, delaying its reuse. */ return !kasan_slab_free(s, x, init); } static inline bool slab_free_freelist_hook(struct kmem_cache *s, void **head, void **tail, int *cnt) { void *object; void *next = *head; void *old_tail = *tail; bool init; if (is_kfence_address(next)) { slab_free_hook(s, next, false); return false; } /* Head and tail of the reconstructed freelist */ *head = NULL; *tail = NULL; init = slab_want_init_on_free(s); do { object = next; next = get_freepointer(s, object); /* If object's reuse doesn't have to be delayed */ if (likely(slab_free_hook(s, object, init))) { /* Move object to the new freelist */ set_freepointer(s, object, *head); *head = object; if (!*tail) *tail = object; } else { /* * Adjust the reconstructed freelist depth * accordingly if object's reuse is delayed. */ --(*cnt); } } while (object != old_tail); return *head != NULL; } static void *setup_object(struct kmem_cache *s, void *object) { setup_object_debug(s, object); object = kasan_init_slab_obj(s, object); if (unlikely(s->ctor)) { kasan_unpoison_new_object(s, object); s->ctor(object); kasan_poison_new_object(s, object); } return object; } /* * Slab allocation and freeing */ static inline struct slab *alloc_slab_page(gfp_t flags, int node, struct kmem_cache_order_objects oo) { struct folio *folio; struct slab *slab; unsigned int order = oo_order(oo); folio = (struct folio *)alloc_pages_node(node, flags, order); if (!folio) return NULL; slab = folio_slab(folio); __folio_set_slab(folio); /* Make the flag visible before any changes to folio->mapping */ smp_wmb(); if (folio_is_pfmemalloc(folio)) slab_set_pfmemalloc(slab); return slab; } #ifdef CONFIG_SLAB_FREELIST_RANDOM /* Pre-initialize the random sequence cache */ static int init_cache_random_seq(struct kmem_cache *s) { unsigned int count = oo_objects(s->oo); int err; /* Bailout if already initialised */ if (s->random_seq) return 0; err = cache_random_seq_create(s, count, GFP_KERNEL); if (err) { pr_err("SLUB: Unable to initialize free list for %s\n", s->name); return err; } /* Transform to an offset on the set of pages */ if (s->random_seq) { unsigned int i; for (i = 0; i < count; i++) s->random_seq[i] *= s->size; } return 0; } /* Initialize each random sequence freelist per cache */ static void __init init_freelist_randomization(void) { struct kmem_cache *s; mutex_lock(&slab_mutex); list_for_each_entry(s, &slab_caches, list) init_cache_random_seq(s); mutex_unlock(&slab_mutex); } /* Get the next entry on the pre-computed freelist randomized */ static void *next_freelist_entry(struct kmem_cache *s, unsigned long *pos, void *start, unsigned long page_limit, unsigned long freelist_count) { unsigned int idx; /* * If the target page allocation failed, the number of objects on the * page might be smaller than the usual size defined by the cache. */ do { idx = s->random_seq[*pos]; *pos += 1; if (*pos >= freelist_count) *pos = 0; } while (unlikely(idx >= page_limit)); return (char *)start + idx; } /* Shuffle the single linked freelist based on a random pre-computed sequence */ static bool shuffle_freelist(struct kmem_cache *s, struct slab *slab) { void *start; void *cur; void *next; unsigned long idx, pos, page_limit, freelist_count; if (slab->objects < 2 || !s->random_seq) return false; freelist_count = oo_objects(s->oo); pos = get_random_u32_below(freelist_count); page_limit = slab->objects * s->size; start = fixup_red_left(s, slab_address(slab)); /* First entry is used as the base of the freelist */ cur = next_freelist_entry(s, &pos, start, page_limit, freelist_count); cur = setup_object(s, cur); slab->freelist = cur; for (idx = 1; idx < slab->objects; idx++) { next = next_freelist_entry(s, &pos, start, page_limit, freelist_count); next = setup_object(s, next); set_freepointer(s, cur, next); cur = next; } set_freepointer(s, cur, NULL); return true; } #else static inline int init_cache_random_seq(struct kmem_cache *s) { return 0; } static inline void init_freelist_randomization(void) { } static inline bool shuffle_freelist(struct kmem_cache *s, struct slab *slab) { return false; } #endif /* CONFIG_SLAB_FREELIST_RANDOM */ static __always_inline void account_slab(struct slab *slab, int order, struct kmem_cache *s, gfp_t gfp) { if (memcg_kmem_online() && (s->flags & SLAB_ACCOUNT)) memcg_alloc_slab_cgroups(slab, s, gfp, true); mod_node_page_state(slab_pgdat(slab), cache_vmstat_idx(s), PAGE_SIZE << order); } static __always_inline void unaccount_slab(struct slab *slab, int order, struct kmem_cache *s) { if (memcg_kmem_online()) memcg_free_slab_cgroups(slab); mod_node_page_state(slab_pgdat(slab), cache_vmstat_idx(s), -(PAGE_SIZE << order)); } static struct slab *allocate_slab(struct kmem_cache *s, gfp_t flags, int node) { struct slab *slab; struct kmem_cache_order_objects oo = s->oo; gfp_t alloc_gfp; void *start, *p, *next; int idx; bool shuffle; flags &= gfp_allowed_mask; flags |= s->allocflags; /* * Let the initial higher-order allocation fail under memory pressure * so we fall-back to the minimum order allocation. */ alloc_gfp = (flags | __GFP_NOWARN | __GFP_NORETRY) & ~__GFP_NOFAIL; if ((alloc_gfp & __GFP_DIRECT_RECLAIM) && oo_order(oo) > oo_order(s->min)) alloc_gfp = (alloc_gfp | __GFP_NOMEMALLOC) & ~__GFP_RECLAIM; slab = alloc_slab_page(alloc_gfp, node, oo); if (unlikely(!slab)) { oo = s->min; alloc_gfp = flags; /* * Allocation may have failed due to fragmentation. * Try a lower order alloc if possible */ slab = alloc_slab_page(alloc_gfp, node, oo); if (unlikely(!slab)) return NULL; stat(s, ORDER_FALLBACK); } slab->objects = oo_objects(oo); slab->inuse = 0; slab->frozen = 0; account_slab(slab, oo_order(oo), s, flags); slab->slab_cache = s; kasan_poison_slab(slab); start = slab_address(slab); setup_slab_debug(s, slab, start); shuffle = shuffle_freelist(s, slab); if (!shuffle) { start = fixup_red_left(s, start); start = setup_object(s, start); slab->freelist = start; for (idx = 0, p = start; idx < slab->objects - 1; idx++) { next = p + s->size; next = setup_object(s, next); set_freepointer(s, p, next); p = next; } set_freepointer(s, p, NULL); } return slab; } static struct slab *new_slab(struct kmem_cache *s, gfp_t flags, int node) { if (unlikely(flags & GFP_SLAB_BUG_MASK)) flags = kmalloc_fix_flags(flags); WARN_ON_ONCE(s->ctor && (flags & __GFP_ZERO)); return allocate_slab(s, flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node); } static void __free_slab(struct kmem_cache *s, struct slab *slab) { struct folio *folio = slab_folio(slab); int order = folio_order(folio); int pages = 1 << order; __slab_clear_pfmemalloc(slab); folio->mapping = NULL; /* Make the mapping reset visible before clearing the flag */ smp_wmb(); __folio_clear_slab(folio); mm_account_reclaimed_pages(pages); unaccount_slab(slab, order, s); __free_pages(&folio->page, order); } static void rcu_free_slab(struct rcu_head *h) { struct slab *slab = container_of(h, struct slab, rcu_head); __free_slab(slab->slab_cache, slab); } static void free_slab(struct kmem_cache *s, struct slab *slab) { if (kmem_cache_debug_flags(s, SLAB_CONSISTENCY_CHECKS)) { void *p; slab_pad_check(s, slab); for_each_object(p, s, slab_address(slab), slab->objects) check_object(s, slab, p, SLUB_RED_INACTIVE); } if (unlikely(s->flags & SLAB_TYPESAFE_BY_RCU)) call_rcu(&slab->rcu_head, rcu_free_slab); else __free_slab(s, slab); } static void discard_slab(struct kmem_cache *s, struct slab *slab) { dec_slabs_node(s, slab_nid(slab), slab->objects); free_slab(s, slab); } /* * SLUB reuses PG_workingset bit to keep track of whether it's on * the per-node partial list. */ static inline bool slab_test_node_partial(const struct slab *slab) { return folio_test_workingset((struct folio *)slab_folio(slab)); } static inline void slab_set_node_partial(struct slab *slab) { set_bit(PG_workingset, folio_flags(slab_folio(slab), 0)); } static inline void slab_clear_node_partial(struct slab *slab) { clear_bit(PG_workingset, folio_flags(slab_folio(slab), 0)); } /* * Management of partially allocated slabs. */ static inline void __add_partial(struct kmem_cache_node *n, struct slab *slab, int tail) { n->nr_partial++; if (tail == DEACTIVATE_TO_TAIL) list_add_tail(&slab->slab_list, &n->partial); else list_add(&slab->slab_list, &n->partial); slab_set_node_partial(slab); } static inline void add_partial(struct kmem_cache_node *n, struct slab *slab, int tail) { lockdep_assert_held(&n->list_lock); __add_partial(n, slab, tail); } static inline void remove_partial(struct kmem_cache_node *n, struct slab *slab) { lockdep_assert_held(&n->list_lock); list_del(&slab->slab_list); slab_clear_node_partial(slab); n->nr_partial--; } /* * Called only for kmem_cache_debug() caches instead of remove_partial(), with a * slab from the n->partial list. Remove only a single object from the slab, do * the alloc_debug_processing() checks and leave the slab on the list, or move * it to full list if it was the last free object. */ static void *alloc_single_from_partial(struct kmem_cache *s, struct kmem_cache_node *n, struct slab *slab, int orig_size) { void *object; lockdep_assert_held(&n->list_lock); object = slab->freelist; slab->freelist = get_freepointer(s, object); slab->inuse++; if (!alloc_debug_processing(s, slab, object, orig_size)) { remove_partial(n, slab); return NULL; } if (slab->inuse == slab->objects) { remove_partial(n, slab); add_full(s, n, slab); } return object; } /* * Called only for kmem_cache_debug() caches to allocate from a freshly * allocated slab. Allocate a single object instead of whole freelist * and put the slab to the partial (or full) list. */ static void *alloc_single_from_new_slab(struct kmem_cache *s, struct slab *slab, int orig_size) { int nid = slab_nid(slab); struct kmem_cache_node *n = get_node(s, nid); unsigned long flags; void *object; object = slab->freelist; slab->freelist = get_freepointer(s, object); slab->inuse = 1; if (!alloc_debug_processing(s, slab, object, orig_size)) /* * It's not really expected that this would fail on a * freshly allocated slab, but a concurrent memory * corruption in theory could cause that. */ return NULL; spin_lock_irqsave(&n->list_lock, flags); if (slab->inuse == slab->objects) add_full(s, n, slab); else add_partial(n, slab, DEACTIVATE_TO_HEAD); inc_slabs_node(s, nid, slab->objects); spin_unlock_irqrestore(&n->list_lock, flags); return object; } #ifdef CONFIG_SLUB_CPU_PARTIAL static void put_cpu_partial(struct kmem_cache *s, struct slab *slab, int drain); #else static inline void put_cpu_partial(struct kmem_cache *s, struct slab *slab, int drain) { } #endif static inline bool pfmemalloc_match(struct slab *slab, gfp_t gfpflags); /* * Try to allocate a partial slab from a specific node. */ static struct slab *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n, struct partial_context *pc) { struct slab *slab, *slab2, *partial = NULL; unsigned long flags; unsigned int partial_slabs = 0; /* * Racy check. If we mistakenly see no partial slabs then we * just allocate an empty slab. If we mistakenly try to get a * partial slab and there is none available then get_partial() * will return NULL. */ if (!n || !n->nr_partial) return NULL; spin_lock_irqsave(&n->list_lock, flags); list_for_each_entry_safe(slab, slab2, &n->partial, slab_list) { if (!pfmemalloc_match(slab, pc->flags)) continue; if (IS_ENABLED(CONFIG_SLUB_TINY) || kmem_cache_debug(s)) { void *object = alloc_single_from_partial(s, n, slab, pc->orig_size); if (object) { partial = slab; pc->object = object; break; } continue; } remove_partial(n, slab); if (!partial) { partial = slab; stat(s, ALLOC_FROM_PARTIAL); } else { put_cpu_partial(s, slab, 0); stat(s, CPU_PARTIAL_NODE); partial_slabs++; } #ifdef CONFIG_SLUB_CPU_PARTIAL if (!kmem_cache_has_cpu_partial(s) || partial_slabs > s->cpu_partial_slabs / 2) break; #else break; #endif } spin_unlock_irqrestore(&n->list_lock, flags); return partial; } /* * Get a slab from somewhere. Search in increasing NUMA distances. */ static struct slab *get_any_partial(struct kmem_cache *s, struct partial_context *pc) { #ifdef CONFIG_NUMA struct zonelist *zonelist; struct zoneref *z; struct zone *zone; enum zone_type highest_zoneidx = gfp_zone(pc->flags); struct slab *slab; unsigned int cpuset_mems_cookie; /* * The defrag ratio allows a configuration of the tradeoffs between * inter node defragmentation and node local allocations. A lower * defrag_ratio increases the tendency to do local allocations * instead of attempting to obtain partial slabs from other nodes. * * If the defrag_ratio is set to 0 then kmalloc() always * returns node local objects. If the ratio is higher then kmalloc() * may return off node objects because partial slabs are obtained * from other nodes and filled up. * * If /sys/kernel/slab/xx/remote_node_defrag_ratio is set to 100 * (which makes defrag_ratio = 1000) then every (well almost) * allocation will first attempt to defrag slab caches on other nodes. * This means scanning over all nodes to look for partial slabs which * may be expensive if we do it every time we are trying to find a slab * with available objects. */ if (!s->remote_node_defrag_ratio || get_cycles() % 1024 > s->remote_node_defrag_ratio) return NULL; do { cpuset_mems_cookie = read_mems_allowed_begin(); zonelist = node_zonelist(mempolicy_slab_node(), pc->flags); for_each_zone_zonelist(zone, z, zonelist, highest_zoneidx) { struct kmem_cache_node *n; n = get_node(s, zone_to_nid(zone)); if (n && cpuset_zone_allowed(zone, pc->flags) && n->nr_partial > s->min_partial) { slab = get_partial_node(s, n, pc); if (slab) { /* * Don't check read_mems_allowed_retry() * here - if mems_allowed was updated in * parallel, that was a harmless race * between allocation and the cpuset * update */ return slab; } } } } while (read_mems_allowed_retry(cpuset_mems_cookie)); #endif /* CONFIG_NUMA */ return NULL; } /* * Get a partial slab, lock it and return it. */ static struct slab *get_partial(struct kmem_cache *s, int node, struct partial_context *pc) { struct slab *slab; int searchnode = node; if (node == NUMA_NO_NODE) searchnode = numa_mem_id(); slab = get_partial_node(s, get_node(s, searchnode), pc); if (slab || node != NUMA_NO_NODE) return slab; return get_any_partial(s, pc); } #ifndef CONFIG_SLUB_TINY #ifdef CONFIG_PREEMPTION /* * Calculate the next globally unique transaction for disambiguation * during cmpxchg. The transactions start with the cpu number and are then * incremented by CONFIG_NR_CPUS. */ #define TID_STEP roundup_pow_of_two(CONFIG_NR_CPUS) #else /* * No preemption supported therefore also no need to check for * different cpus. */ #define TID_STEP 1 #endif /* CONFIG_PREEMPTION */ static inline unsigned long next_tid(unsigned long tid) { return tid + TID_STEP; } #ifdef SLUB_DEBUG_CMPXCHG static inline unsigned int tid_to_cpu(unsigned long tid) { return tid % TID_STEP; } static inline unsigned long tid_to_event(unsigned long tid) { return tid / TID_STEP; } #endif static inline unsigned int init_tid(int cpu) { return cpu; } static inline void note_cmpxchg_failure(const char *n, const struct kmem_cache *s, unsigned long tid) { #ifdef SLUB_DEBUG_CMPXCHG unsigned long actual_tid = __this_cpu_read(s->cpu_slab->tid); pr_info("%s %s: cmpxchg redo ", n, s->name); #ifdef CONFIG_PREEMPTION if (tid_to_cpu(tid) != tid_to_cpu(actual_tid)) pr_warn("due to cpu change %d -> %d\n", tid_to_cpu(tid), tid_to_cpu(actual_tid)); else #endif if (tid_to_event(tid) != tid_to_event(actual_tid)) pr_warn("due to cpu running other code. Event %ld->%ld\n", tid_to_event(tid), tid_to_event(actual_tid)); else pr_warn("for unknown reason: actual=%lx was=%lx target=%lx\n", actual_tid, tid, next_tid(tid)); #endif stat(s, CMPXCHG_DOUBLE_CPU_FAIL); } static void init_kmem_cache_cpus(struct kmem_cache *s) { int cpu; struct kmem_cache_cpu *c; for_each_possible_cpu(cpu) { c = per_cpu_ptr(s->cpu_slab, cpu); local_lock_init(&c->lock); c->tid = init_tid(cpu); } } /* * Finishes removing the cpu slab. Merges cpu's freelist with slab's freelist, * unfreezes the slabs and puts it on the proper list. * Assumes the slab has been already safely taken away from kmem_cache_cpu * by the caller. */ static void deactivate_slab(struct kmem_cache *s, struct slab *slab, void *freelist) { struct kmem_cache_node *n = get_node(s, slab_nid(slab)); int free_delta = 0; void *nextfree, *freelist_iter, *freelist_tail; int tail = DEACTIVATE_TO_HEAD; unsigned long flags = 0; struct slab new; struct slab old; if (slab->freelist) { stat(s, DEACTIVATE_REMOTE_FREES); tail = DEACTIVATE_TO_TAIL; } /* * Stage one: Count the objects on cpu's freelist as free_delta and * remember the last object in freelist_tail for later splicing. */ freelist_tail = NULL; freelist_iter = freelist; while (freelist_iter) { nextfree = get_freepointer(s, freelist_iter); /* * If 'nextfree' is invalid, it is possible that the object at * 'freelist_iter' is already corrupted. So isolate all objects * starting at 'freelist_iter' by skipping them. */ if (freelist_corrupted(s, slab, &freelist_iter, nextfree)) break; freelist_tail = freelist_iter; free_delta++; freelist_iter = nextfree; } /* * Stage two: Unfreeze the slab while splicing the per-cpu * freelist to the head of slab's freelist. */ do { old.freelist = READ_ONCE(slab->freelist); old.counters = READ_ONCE(slab->counters); VM_BUG_ON(!old.frozen); /* Determine target state of the slab */ new.counters = old.counters; new.frozen = 0; if (freelist_tail) { new.inuse -= free_delta; set_freepointer(s, freelist_tail, old.freelist); new.freelist = freelist; } else { new.freelist = old.freelist; } } while (!slab_update_freelist(s, slab, old.freelist, old.counters, new.freelist, new.counters, "unfreezing slab")); /* * Stage three: Manipulate the slab list based on the updated state. */ if (!new.inuse && n->nr_partial >= s->min_partial) { stat(s, DEACTIVATE_EMPTY); discard_slab(s, slab); stat(s, FREE_SLAB); } else if (new.freelist) { spin_lock_irqsave(&n->list_lock, flags); add_partial(n, slab, tail); spin_unlock_irqrestore(&n->list_lock, flags); stat(s, tail); } else { stat(s, DEACTIVATE_FULL); } } #ifdef CONFIG_SLUB_CPU_PARTIAL static void __put_partials(struct kmem_cache *s, struct slab *partial_slab) { struct kmem_cache_node *n = NULL, *n2 = NULL; struct slab *slab, *slab_to_discard = NULL; unsigned long flags = 0; while (partial_slab) { slab = partial_slab; partial_slab = slab->next; n2 = get_node(s, slab_nid(slab)); if (n != n2) { if (n) spin_unlock_irqrestore(&n->list_lock, flags); n = n2; spin_lock_irqsave(&n->list_lock, flags); } if (unlikely(!slab->inuse && n->nr_partial >= s->min_partial)) { slab->next = slab_to_discard; slab_to_discard = slab; } else { add_partial(n, slab, DEACTIVATE_TO_TAIL); stat(s, FREE_ADD_PARTIAL); } } if (n) spin_unlock_irqrestore(&n->list_lock, flags); while (slab_to_discard) { slab = slab_to_discard; slab_to_discard = slab_to_discard->next; stat(s, DEACTIVATE_EMPTY); discard_slab(s, slab); stat(s, FREE_SLAB); } } /* * Put all the cpu partial slabs to the node partial list. */ static void put_partials(struct kmem_cache *s) { struct slab *partial_slab; unsigned long flags; local_lock_irqsave(&s->cpu_slab->lock, flags); partial_slab = this_cpu_read(s->cpu_slab->partial); this_cpu_write(s->cpu_slab->partial, NULL); local_unlock_irqrestore(&s->cpu_slab->lock, flags); if (partial_slab) __put_partials(s, partial_slab); } static void put_partials_cpu(struct kmem_cache *s, struct kmem_cache_cpu *c) { struct slab *partial_slab; partial_slab = slub_percpu_partial(c); c->partial = NULL; if (partial_slab) __put_partials(s, partial_slab); } /* * Put a slab into a partial slab slot if available. * * If we did not find a slot then simply move all the partials to the * per node partial list. */ static void put_cpu_partial(struct kmem_cache *s, struct slab *slab, int drain) { struct slab *oldslab; struct slab *slab_to_put = NULL; unsigned long flags; int slabs = 0; local_lock_irqsave(&s->cpu_slab->lock, flags); oldslab = this_cpu_read(s->cpu_slab->partial); if (oldslab) { if (drain && oldslab->slabs >= s->cpu_partial_slabs) { /* * Partial array is full. Move the existing set to the * per node partial list. Postpone the actual unfreezing * outside of the critical section. */ slab_to_put = oldslab; oldslab = NULL; } else { slabs = oldslab->slabs; } } slabs++; slab->slabs = slabs; slab->next = oldslab; this_cpu_write(s->cpu_slab->partial, slab); local_unlock_irqrestore(&s->cpu_slab->lock, flags); if (slab_to_put) { __put_partials(s, slab_to_put); stat(s, CPU_PARTIAL_DRAIN); } } #else /* CONFIG_SLUB_CPU_PARTIAL */ static inline void put_partials(struct kmem_cache *s) { } static inline void put_partials_cpu(struct kmem_cache *s, struct kmem_cache_cpu *c) { } #endif /* CONFIG_SLUB_CPU_PARTIAL */ static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c) { unsigned long flags; struct slab *slab; void *freelist; local_lock_irqsave(&s->cpu_slab->lock, flags); slab = c->slab; freelist = c->freelist; c->slab = NULL; c->freelist = NULL; c->tid = next_tid(c->tid); local_unlock_irqrestore(&s->cpu_slab->lock, flags); if (slab) { deactivate_slab(s, slab, freelist); stat(s, CPUSLAB_FLUSH); } } static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) { struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu); void *freelist = c->freelist; struct slab *slab = c->slab; c->slab = NULL; c->freelist = NULL; c->tid = next_tid(c->tid); if (slab) { deactivate_slab(s, slab, freelist); stat(s, CPUSLAB_FLUSH); } put_partials_cpu(s, c); } struct slub_flush_work { struct work_struct work; struct kmem_cache *s; bool skip; }; /* * Flush cpu slab. * * Called from CPU work handler with migration disabled. */ static void flush_cpu_slab(struct work_struct *w) { struct kmem_cache *s; struct kmem_cache_cpu *c; struct slub_flush_work *sfw; sfw = container_of(w, struct slub_flush_work, work); s = sfw->s; c = this_cpu_ptr(s->cpu_slab); if (c->slab) flush_slab(s, c); put_partials(s); } static bool has_cpu_slab(int cpu, struct kmem_cache *s) { struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu); return c->slab || slub_percpu_partial(c); } static DEFINE_MUTEX(flush_lock); static DEFINE_PER_CPU(struct slub_flush_work, slub_flush); static void flush_all_cpus_locked(struct kmem_cache *s) { struct slub_flush_work *sfw; unsigned int cpu; lockdep_assert_cpus_held(); mutex_lock(&flush_lock); for_each_online_cpu(cpu) { sfw = &per_cpu(slub_flush, cpu); if (!has_cpu_slab(cpu, s)) { sfw->skip = true; continue; } INIT_WORK(&sfw->work, flush_cpu_slab); sfw->skip = false; sfw->s = s; queue_work_on(cpu, flushwq, &sfw->work); } for_each_online_cpu(cpu) { sfw = &per_cpu(slub_flush, cpu); if (sfw->skip) continue; flush_work(&sfw->work); } mutex_unlock(&flush_lock); } static void flush_all(struct kmem_cache *s) { cpus_read_lock(); flush_all_cpus_locked(s); cpus_read_unlock(); } /* * Use the cpu notifier to insure that the cpu slabs are flushed when * necessary. */ static int slub_cpu_dead(unsigned int cpu) { struct kmem_cache *s; mutex_lock(&slab_mutex); list_for_each_entry(s, &slab_caches, list) __flush_cpu_slab(s, cpu); mutex_unlock(&slab_mutex); return 0; } #else /* CONFIG_SLUB_TINY */ static inline void flush_all_cpus_locked(struct kmem_cache *s) { } static inline void flush_all(struct kmem_cache *s) { } static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) { } static inline int slub_cpu_dead(unsigned int cpu) { return 0; } #endif /* CONFIG_SLUB_TINY */ /* * Check if the objects in a per cpu structure fit numa * locality expectations. */ static inline int node_match(struct slab *slab, int node) { #ifdef CONFIG_NUMA if (node != NUMA_NO_NODE && slab_nid(slab) != node) return 0; #endif return 1; } #ifdef CONFIG_SLUB_DEBUG static int count_free(struct slab *slab) { return slab->objects - slab->inuse; } static inline unsigned long node_nr_objs(struct kmem_cache_node *n) { return atomic_long_read(&n->total_objects); } /* Supports checking bulk free of a constructed freelist */ static inline bool free_debug_processing(struct kmem_cache *s, struct slab *slab, void *head, void *tail, int *bulk_cnt, unsigned long addr, depot_stack_handle_t handle) { bool checks_ok = false; void *object = head; int cnt = 0; if (s->flags & SLAB_CONSISTENCY_CHECKS) { if (!check_slab(s, slab)) goto out; } if (slab->inuse < *bulk_cnt) { slab_err(s, slab, "Slab has %d allocated objects but %d are to be freed\n", slab->inuse, *bulk_cnt); goto out; } next_object: if (++cnt > *bulk_cnt) goto out_cnt; if (s->flags & SLAB_CONSISTENCY_CHECKS) { if (!free_consistency_checks(s, slab, object, addr)) goto out; } if (s->flags & SLAB_STORE_USER) set_track_update(s, object, TRACK_FREE, addr, handle); trace(s, slab, object, 0); /* Freepointer not overwritten by init_object(), SLAB_POISON moved it */ init_object(s, object, SLUB_RED_INACTIVE); /* Reached end of constructed freelist yet? */ if (object != tail) { object = get_freepointer(s, object); goto next_object; } checks_ok = true; out_cnt: if (cnt != *bulk_cnt) { slab_err(s, slab, "Bulk free expected %d objects but found %d\n", *bulk_cnt, cnt); *bulk_cnt = cnt; } out: if (!checks_ok) slab_fix(s, "Object at 0x%p not freed", object); return checks_ok; } #endif /* CONFIG_SLUB_DEBUG */ #if defined(CONFIG_SLUB_DEBUG) || defined(SLAB_SUPPORTS_SYSFS) static unsigned long count_partial(struct kmem_cache_node *n, int (*get_count)(struct slab *)) { unsigned long flags; unsigned long x = 0; struct slab *slab; spin_lock_irqsave(&n->list_lock, flags); list_for_each_entry(slab, &n->partial, slab_list) x += get_count(slab); spin_unlock_irqrestore(&n->list_lock, flags); return x; } #endif /* CONFIG_SLUB_DEBUG || SLAB_SUPPORTS_SYSFS */ #ifdef CONFIG_SLUB_DEBUG static noinline void slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid) { static DEFINE_RATELIMIT_STATE(slub_oom_rs, DEFAULT_RATELIMIT_INTERVAL, DEFAULT_RATELIMIT_BURST); int node; struct kmem_cache_node *n; if ((gfpflags & __GFP_NOWARN) || !__ratelimit(&slub_oom_rs)) return; pr_warn("SLUB: Unable to allocate memory on node %d, gfp=%#x(%pGg)\n", nid, gfpflags, &gfpflags); pr_warn(" cache: %s, object size: %u, buffer size: %u, default order: %u, min order: %u\n", s->name, s->object_size, s->size, oo_order(s->oo), oo_order(s->min)); if (oo_order(s->min) > get_order(s->object_size)) pr_warn(" %s debugging increased min order, use slab_debug=O to disable.\n", s->name); for_each_kmem_cache_node(s, node, n) { unsigned long nr_slabs; unsigned long nr_objs; unsigned long nr_free; nr_free = count_partial(n, count_free); nr_slabs = node_nr_slabs(n); nr_objs = node_nr_objs(n); pr_warn(" node %d: slabs: %ld, objs: %ld, free: %ld\n", node, nr_slabs, nr_objs, nr_free); } } #else /* CONFIG_SLUB_DEBUG */ static inline void slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid) { } #endif static inline bool pfmemalloc_match(struct slab *slab, gfp_t gfpflags) { if (unlikely(slab_test_pfmemalloc(slab))) return gfp_pfmemalloc_allowed(gfpflags); return true; } #ifndef CONFIG_SLUB_TINY static inline bool __update_cpu_freelist_fast(struct kmem_cache *s, void *freelist_old, void *freelist_new, unsigned long tid) { freelist_aba_t old = { .freelist = freelist_old, .counter = tid }; freelist_aba_t new = { .freelist = freelist_new, .counter = next_tid(tid) }; return this_cpu_try_cmpxchg_freelist(s->cpu_slab->freelist_tid.full, &old.full, new.full); } /* * Check the slab->freelist and either transfer the freelist to the * per cpu freelist or deactivate the slab. * * The slab is still frozen if the return value is not NULL. * * If this function returns NULL then the slab has been unfrozen. */ static inline void *get_freelist(struct kmem_cache *s, struct slab *slab) { struct slab new; unsigned long counters; void *freelist; lockdep_assert_held(this_cpu_ptr(&s->cpu_slab->lock)); do { freelist = slab->freelist; counters = slab->counters; new.counters = counters; new.inuse = slab->objects; new.frozen = freelist != NULL; } while (!__slab_update_freelist(s, slab, freelist, counters, NULL, new.counters, "get_freelist")); return freelist; } /* * Freeze the partial slab and return the pointer to the freelist. */ static inline void *freeze_slab(struct kmem_cache *s, struct slab *slab) { struct slab new; unsigned long counters; void *freelist; do { freelist = slab->freelist; counters = slab->counters; new.counters = counters; VM_BUG_ON(new.frozen); new.inuse = slab->objects; new.frozen = 1; } while (!slab_update_freelist(s, slab, freelist, counters, NULL, new.counters, "freeze_slab")); return freelist; } /* * Slow path. The lockless freelist is empty or we need to perform * debugging duties. * * Processing is still very fast if new objects have been freed to the * regular freelist. In that case we simply take over the regular freelist * as the lockless freelist and zap the regular freelist. * * If that is not working then we fall back to the partial lists. We take the * first element of the freelist as the object to allocate now and move the * rest of the freelist to the lockless freelist. * * And if we were unable to get a new slab from the partial slab lists then * we need to allocate a new slab. This is the slowest path since it involves * a call to the page allocator and the setup of a new slab. * * Version of __slab_alloc to use when we know that preemption is * already disabled (which is the case for bulk allocation). */ static void *___slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, unsigned long addr, struct kmem_cache_cpu *c, unsigned int orig_size) { void *freelist; struct slab *slab; unsigned long flags; struct partial_context pc; stat(s, ALLOC_SLOWPATH); reread_slab: slab = READ_ONCE(c->slab); if (!slab) { /* * if the node is not online or has no normal memory, just * ignore the node constraint */ if (unlikely(node != NUMA_NO_NODE && !node_isset(node, slab_nodes))) node = NUMA_NO_NODE; goto new_slab; } if (unlikely(!node_match(slab, node))) { /* * same as above but node_match() being false already * implies node != NUMA_NO_NODE */ if (!node_isset(node, slab_nodes)) { node = NUMA_NO_NODE; } else { stat(s, ALLOC_NODE_MISMATCH); goto deactivate_slab; } } /* * By rights, we should be searching for a slab page that was * PFMEMALLOC but right now, we are losing the pfmemalloc * information when the page leaves the per-cpu allocator */ if (unlikely(!pfmemalloc_match(slab, gfpflags))) goto deactivate_slab; /* must check again c->slab in case we got preempted and it changed */ local_lock_irqsave(&s->cpu_slab->lock, flags); if (unlikely(slab != c->slab)) { local_unlock_irqrestore(&s->cpu_slab->lock, flags); goto reread_slab; } freelist = c->freelist; if (freelist) goto load_freelist; freelist = get_freelist(s, slab); if (!freelist) { c->slab = NULL; c->tid = next_tid(c->tid); local_unlock_irqrestore(&s->cpu_slab->lock, flags); stat(s, DEACTIVATE_BYPASS); goto new_slab; } stat(s, ALLOC_REFILL); load_freelist: lockdep_assert_held(this_cpu_ptr(&s->cpu_slab->lock)); /* * freelist is pointing to the list of objects to be used. * slab is pointing to the slab from which the objects are obtained. * That slab must be frozen for per cpu allocations to work. */ VM_BUG_ON(!c->slab->frozen); c->freelist = get_freepointer(s, freelist); c->tid = next_tid(c->tid); local_unlock_irqrestore(&s->cpu_slab->lock, flags); return freelist; deactivate_slab: local_lock_irqsave(&s->cpu_slab->lock, flags); if (slab != c->slab) { local_unlock_irqrestore(&s->cpu_slab->lock, flags); goto reread_slab; } freelist = c->freelist; c->slab = NULL; c->freelist = NULL; c->tid = next_tid(c->tid); local_unlock_irqrestore(&s->cpu_slab->lock, flags); deactivate_slab(s, slab, freelist); new_slab: #ifdef CONFIG_SLUB_CPU_PARTIAL while (slub_percpu_partial(c)) { local_lock_irqsave(&s->cpu_slab->lock, flags); if (unlikely(c->slab)) { local_unlock_irqrestore(&s->cpu_slab->lock, flags); goto reread_slab; } if (unlikely(!slub_percpu_partial(c))) { local_unlock_irqrestore(&s->cpu_slab->lock, flags); /* we were preempted and partial list got empty */ goto new_objects; } slab = slub_percpu_partial(c); slub_set_percpu_partial(c, slab); if (likely(node_match(slab, node) && pfmemalloc_match(slab, gfpflags))) { c->slab = slab; freelist = get_freelist(s, slab); VM_BUG_ON(!freelist); stat(s, CPU_PARTIAL_ALLOC); goto load_freelist; } local_unlock_irqrestore(&s->cpu_slab->lock, flags); slab->next = NULL; __put_partials(s, slab); } #endif new_objects: pc.flags = gfpflags; pc.orig_size = orig_size; slab = get_partial(s, node, &pc); if (slab) { if (kmem_cache_debug(s)) { freelist = pc.object; /* * For debug caches here we had to go through * alloc_single_from_partial() so just store the * tracking info and return the object. */ if (s->flags & SLAB_STORE_USER) set_track(s, freelist, TRACK_ALLOC, addr); return freelist; } freelist = freeze_slab(s, slab); goto retry_load_slab; } slub_put_cpu_ptr(s->cpu_slab); slab = new_slab(s, gfpflags, node); c = slub_get_cpu_ptr(s->cpu_slab); if (unlikely(!slab)) { slab_out_of_memory(s, gfpflags, node); return NULL; } stat(s, ALLOC_SLAB); if (kmem_cache_debug(s)) { freelist = alloc_single_from_new_slab(s, slab, orig_size); if (unlikely(!freelist)) goto new_objects; if (s->flags & SLAB_STORE_USER) set_track(s, freelist, TRACK_ALLOC, addr); return freelist; } /* * No other reference to the slab yet so we can * muck around with it freely without cmpxchg */ freelist = slab->freelist; slab->freelist = NULL; slab->inuse = slab->objects; slab->frozen = 1; inc_slabs_node(s, slab_nid(slab), slab->objects); if (unlikely(!pfmemalloc_match(slab, gfpflags))) { /* * For !pfmemalloc_match() case we don't load freelist so that * we don't make further mismatched allocations easier. */ deactivate_slab(s, slab, get_freepointer(s, freelist)); return freelist; } retry_load_slab: local_lock_irqsave(&s->cpu_slab->lock, flags); if (unlikely(c->slab)) { void *flush_freelist = c->freelist; struct slab *flush_slab = c->slab; c->slab = NULL; c->freelist = NULL; c->tid = next_tid(c->tid); local_unlock_irqrestore(&s->cpu_slab->lock, flags); deactivate_slab(s, flush_slab, flush_freelist); stat(s, CPUSLAB_FLUSH); goto retry_load_slab; } c->slab = slab; goto load_freelist; } /* * A wrapper for ___slab_alloc() for contexts where preemption is not yet * disabled. Compensates for possible cpu changes by refetching the per cpu area * pointer. */ static void *__slab_alloc(struct kmem_cache *s, gfp_t gfpflags, int node, unsigned long addr, struct kmem_cache_cpu *c, unsigned int orig_size) { void *p; #ifdef CONFIG_PREEMPT_COUNT /* * We may have been preempted and rescheduled on a different * cpu before disabling preemption. Need to reload cpu area * pointer. */ c = slub_get_cpu_ptr(s->cpu_slab); #endif p = ___slab_alloc(s, gfpflags, node, addr, c, orig_size); #ifdef CONFIG_PREEMPT_COUNT slub_put_cpu_ptr(s->cpu_slab); #endif return p; } static __always_inline void *__slab_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node, unsigned long addr, size_t orig_size) { struct kmem_cache_cpu *c; struct slab *slab; unsigned long tid; void *object; redo: /* * Must read kmem_cache cpu data via this cpu ptr. Preemption is * enabled. We may switch back and forth between cpus while * reading from one cpu area. That does not matter as long * as we end up on the original cpu again when doing the cmpxchg. * * We must guarantee that tid and kmem_cache_cpu are retrieved on the * same cpu. We read first the kmem_cache_cpu pointer and use it to read * the tid. If we are preempted and switched to another cpu between the * two reads, it's OK as the two are still associated with the same cpu * and cmpxchg later will validate the cpu. */ c = raw_cpu_ptr(s->cpu_slab); tid = READ_ONCE(c->tid); /* * Irqless object alloc/free algorithm used here depends on sequence * of fetching cpu_slab's data. tid should be fetched before anything * on c to guarantee that object and slab associated with previous tid * won't be used with current tid. If we fetch tid first, object and * slab could be one associated with next tid and our alloc/free * request will be failed. In this case, we will retry. So, no problem. */ barrier(); /* * The transaction ids are globally unique per cpu and per operation on * a per cpu queue. Thus they can be guarantee that the cmpxchg_double * occurs on the right processor and that there was no operation on the * linked list in between. */ object = c->freelist; slab = c->slab; if (!USE_LOCKLESS_FAST_PATH() || unlikely(!object || !slab || !node_match(slab, node))) { object = __slab_alloc(s, gfpflags, node, addr, c, orig_size); } else { void *next_object = get_freepointer_safe(s, object); /* * The cmpxchg will only match if there was no additional * operation and if we are on the right processor. * * The cmpxchg does the following atomically (without lock * semantics!) * 1. Relocate first pointer to the current per cpu area. * 2. Verify that tid and freelist have not been changed * 3. If they were not changed replace tid and freelist * * Since this is without lock semantics the protection is only * against code executing on this cpu *not* from access by * other cpus. */ if (unlikely(!__update_cpu_freelist_fast(s, object, next_object, tid))) { note_cmpxchg_failure("slab_alloc", s, tid); goto redo; } prefetch_freepointer(s, next_object); stat(s, ALLOC_FASTPATH); } return object; } #else /* CONFIG_SLUB_TINY */ static void *__slab_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node, unsigned long addr, size_t orig_size) { struct partial_context pc; struct slab *slab; void *object; pc.flags = gfpflags; pc.orig_size = orig_size; slab = get_partial(s, node, &pc); if (slab) return pc.object; slab = new_slab(s, gfpflags, node); if (unlikely(!slab)) { slab_out_of_memory(s, gfpflags, node); return NULL; } object = alloc_single_from_new_slab(s, slab, orig_size); return object; } #endif /* CONFIG_SLUB_TINY */ /* * If the object has been wiped upon free, make sure it's fully initialized by * zeroing out freelist pointer. */ static __always_inline void maybe_wipe_obj_freeptr(struct kmem_cache *s, void *obj) { if (unlikely(slab_want_init_on_free(s)) && obj) memset((void *)((char *)kasan_reset_tag(obj) + s->offset), 0, sizeof(void *)); } noinline int should_failslab(struct kmem_cache *s, gfp_t gfpflags) { if (__should_failslab(s, gfpflags)) return -ENOMEM; return 0; } ALLOW_ERROR_INJECTION(should_failslab, ERRNO); static __fastpath_inline struct kmem_cache *slab_pre_alloc_hook(struct kmem_cache *s, struct list_lru *lru, struct obj_cgroup **objcgp, size_t size, gfp_t flags) { flags &= gfp_allowed_mask; might_alloc(flags); if (unlikely(should_failslab(s, flags))) return NULL; if (unlikely(!memcg_slab_pre_alloc_hook(s, lru, objcgp, size, flags))) return NULL; return s; } static __fastpath_inline void slab_post_alloc_hook(struct kmem_cache *s, struct obj_cgroup *objcg, gfp_t flags, size_t size, void **p, bool init, unsigned int orig_size) { unsigned int zero_size = s->object_size; bool kasan_init = init; size_t i; gfp_t init_flags = flags & gfp_allowed_mask; /* * For kmalloc object, the allocated memory size(object_size) is likely * larger than the requested size(orig_size). If redzone check is * enabled for the extra space, don't zero it, as it will be redzoned * soon. The redzone operation for this extra space could be seen as a * replacement of current poisoning under certain debug option, and * won't break other sanity checks. */ if (kmem_cache_debug_flags(s, SLAB_STORE_USER | SLAB_RED_ZONE) && (s->flags & SLAB_KMALLOC)) zero_size = orig_size; /* * When slab_debug is enabled, avoid memory initialization integrated * into KASAN and instead zero out the memory via the memset below with * the proper size. Otherwise, KASAN might overwrite SLUB redzones and * cause false-positive reports. This does not lead to a performance * penalty on production builds, as slab_debug is not intended to be * enabled there. */ if (__slub_debug_enabled()) kasan_init = false; /* * As memory initialization might be integrated into KASAN, * kasan_slab_alloc and initialization memset must be * kept together to avoid discrepancies in behavior. * * As p[i] might get tagged, memset and kmemleak hook come after KASAN. */ for (i = 0; i < size; i++) { p[i] = kasan_slab_alloc(s, p[i], init_flags, kasan_init); if (p[i] && init && (!kasan_init || !kasan_has_integrated_init())) memset(p[i], 0, zero_size); kmemleak_alloc_recursive(p[i], s->object_size, 1, s->flags, init_flags); kmsan_slab_alloc(s, p[i], init_flags); } memcg_slab_post_alloc_hook(s, objcg, flags, size, p); } /* * Inlined fastpath so that allocation functions (kmalloc, kmem_cache_alloc) * have the fastpath folded into their functions. So no function call * overhead for requests that can be satisfied on the fastpath. * * The fastpath works by first checking if the lockless freelist can be used. * If not then __slab_alloc is called for slow processing. * * Otherwise we can simply pick the next object from the lockless free list. */ static __fastpath_inline void *slab_alloc_node(struct kmem_cache *s, struct list_lru *lru, gfp_t gfpflags, int node, unsigned long addr, size_t orig_size) { void *object; struct obj_cgroup *objcg = NULL; bool init = false; s = slab_pre_alloc_hook(s, lru, &objcg, 1, gfpflags); if (unlikely(!s)) return NULL; object = kfence_alloc(s, orig_size, gfpflags); if (unlikely(object)) goto out; object = __slab_alloc_node(s, gfpflags, node, addr, orig_size); maybe_wipe_obj_freeptr(s, object); init = slab_want_init_on_alloc(gfpflags, s); out: /* * When init equals 'true', like for kzalloc() family, only * @orig_size bytes might be zeroed instead of s->object_size */ slab_post_alloc_hook(s, objcg, gfpflags, 1, &object, init, orig_size); return object; } void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags) { void *ret = slab_alloc_node(s, NULL, gfpflags, NUMA_NO_NODE, _RET_IP_, s->object_size); trace_kmem_cache_alloc(_RET_IP_, ret, s, gfpflags, NUMA_NO_NODE); return ret; } EXPORT_SYMBOL(kmem_cache_alloc); void *kmem_cache_alloc_lru(struct kmem_cache *s, struct list_lru *lru, gfp_t gfpflags) { void *ret = slab_alloc_node(s, lru, gfpflags, NUMA_NO_NODE, _RET_IP_, s->object_size); trace_kmem_cache_alloc(_RET_IP_, ret, s, gfpflags, NUMA_NO_NODE); return ret; } EXPORT_SYMBOL(kmem_cache_alloc_lru); /** * kmem_cache_alloc_node - Allocate an object on the specified node * @s: The cache to allocate from. * @gfpflags: See kmalloc(). * @node: node number of the target node. * * Identical to kmem_cache_alloc but it will allocate memory on the given * node, which can improve the performance for cpu bound structures. * * Fallback to other node is possible if __GFP_THISNODE is not set. * * Return: pointer to the new object or %NULL in case of error */ void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node) { void *ret = slab_alloc_node(s, NULL, gfpflags, node, _RET_IP_, s->object_size); trace_kmem_cache_alloc(_RET_IP_, ret, s, gfpflags, node); return ret; } EXPORT_SYMBOL(kmem_cache_alloc_node); /* * To avoid unnecessary overhead, we pass through large allocation requests * directly to the page allocator. We use __GFP_COMP, because we will need to * know the allocation order to free the pages properly in kfree. */ static void *__kmalloc_large_node(size_t size, gfp_t flags, int node) { struct folio *folio; void *ptr = NULL; unsigned int order = get_order(size); if (unlikely(flags & GFP_SLAB_BUG_MASK)) flags = kmalloc_fix_flags(flags); flags |= __GFP_COMP; folio = (struct folio *)alloc_pages_node(node, flags, order); if (folio) { ptr = folio_address(folio); lruvec_stat_mod_folio(folio, NR_SLAB_UNRECLAIMABLE_B, PAGE_SIZE << order); } ptr = kasan_kmalloc_large(ptr, size, flags); /* As ptr might get tagged, call kmemleak hook after KASAN. */ kmemleak_alloc(ptr, size, 1, flags); kmsan_kmalloc_large(ptr, size, flags); return ptr; } void *kmalloc_large(size_t size, gfp_t flags) { void *ret = __kmalloc_large_node(size, flags, NUMA_NO_NODE); trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << get_order(size), flags, NUMA_NO_NODE); return ret; } EXPORT_SYMBOL(kmalloc_large); void *kmalloc_large_node(size_t size, gfp_t flags, int node) { void *ret = __kmalloc_large_node(size, flags, node); trace_kmalloc(_RET_IP_, ret, size, PAGE_SIZE << get_order(size), flags, node); return ret; } EXPORT_SYMBOL(kmalloc_large_node); static __always_inline void *__do_kmalloc_node(size_t size, gfp_t flags, int node, unsigned long caller) { struct kmem_cache *s; void *ret; if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) { ret = __kmalloc_large_node(size, flags, node); trace_kmalloc(caller, ret, size, PAGE_SIZE << get_order(size), flags, node); return ret; } if (unlikely(!size)) return ZERO_SIZE_PTR; s = kmalloc_slab(size, flags, caller); ret = slab_alloc_node(s, NULL, flags, node, caller, size); ret = kasan_kmalloc(s, ret, size, flags); trace_kmalloc(caller, ret, size, s->size, flags, node); return ret; } void *__kmalloc_node(size_t size, gfp_t flags, int node) { return __do_kmalloc_node(size, flags, node, _RET_IP_); } EXPORT_SYMBOL(__kmalloc_node); void *__kmalloc(size_t size, gfp_t flags) { return __do_kmalloc_node(size, flags, NUMA_NO_NODE, _RET_IP_); } EXPORT_SYMBOL(__kmalloc); void *__kmalloc_node_track_caller(size_t size, gfp_t flags, int node, unsigned long caller) { return __do_kmalloc_node(size, flags, node, caller); } EXPORT_SYMBOL(__kmalloc_node_track_caller); void *kmalloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size) { void *ret = slab_alloc_node(s, NULL, gfpflags, NUMA_NO_NODE, _RET_IP_, size); trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags, NUMA_NO_NODE); ret = kasan_kmalloc(s, ret, size, gfpflags); return ret; } EXPORT_SYMBOL(kmalloc_trace); void *kmalloc_node_trace(struct kmem_cache *s, gfp_t gfpflags, int node, size_t size) { void *ret = slab_alloc_node(s, NULL, gfpflags, node, _RET_IP_, size); trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags, node); ret = kasan_kmalloc(s, ret, size, gfpflags); return ret; } EXPORT_SYMBOL(kmalloc_node_trace); static noinline void free_to_partial_list( struct kmem_cache *s, struct slab *slab, void *head, void *tail, int bulk_cnt, unsigned long addr) { struct kmem_cache_node *n = get_node(s, slab_nid(slab)); struct slab *slab_free = NULL; int cnt = bulk_cnt; unsigned long flags; depot_stack_handle_t handle = 0; if (s->flags & SLAB_STORE_USER) handle = set_track_prepare(); spin_lock_irqsave(&n->list_lock, flags); if (free_debug_processing(s, slab, head, tail, &cnt, addr, handle)) { void *prior = slab->freelist; /* Perform the actual freeing while we still hold the locks */ slab->inuse -= cnt; set_freepointer(s, tail, prior); slab->freelist = head; /* * If the slab is empty, and node's partial list is full, * it should be discarded anyway no matter it's on full or * partial list. */ if (slab->inuse == 0 && n->nr_partial >= s->min_partial) slab_free = slab; if (!prior) { /* was on full list */ remove_full(s, n, slab); if (!slab_free) { add_partial(n, slab, DEACTIVATE_TO_TAIL); stat(s, FREE_ADD_PARTIAL); } } else if (slab_free) { remove_partial(n, slab); stat(s, FREE_REMOVE_PARTIAL); } } if (slab_free) { /* * Update the counters while still holding n->list_lock to * prevent spurious validation warnings */ dec_slabs_node(s, slab_nid(slab_free), slab_free->objects); } spin_unlock_irqrestore(&n->list_lock, flags); if (slab_free) { stat(s, FREE_SLAB); free_slab(s, slab_free); } } /* * Slow path handling. This may still be called frequently since objects * have a longer lifetime than the cpu slabs in most processing loads. * * So we still attempt to reduce cache line usage. Just take the slab * lock and free the item. If there is no additional partial slab * handling required then we can return immediately. */ static void __slab_free(struct kmem_cache *s, struct slab *slab, void *head, void *tail, int cnt, unsigned long addr) { void *prior; int was_frozen; struct slab new; unsigned long counters; struct kmem_cache_node *n = NULL; unsigned long flags; bool on_node_partial; stat(s, FREE_SLOWPATH); if (IS_ENABLED(CONFIG_SLUB_TINY) || kmem_cache_debug(s)) { free_to_partial_list(s, slab, head, tail, cnt, addr); return; } do { if (unlikely(n)) { spin_unlock_irqrestore(&n->list_lock, flags); n = NULL; } prior = slab->freelist; counters = slab->counters; set_freepointer(s, tail, prior); new.counters = counters; was_frozen = new.frozen; new.inuse -= cnt; if ((!new.inuse || !prior) && !was_frozen) { /* Needs to be taken off a list */ if (!kmem_cache_has_cpu_partial(s) || prior) { n = get_node(s, slab_nid(slab)); /* * Speculatively acquire the list_lock. * If the cmpxchg does not succeed then we may * drop the list_lock without any processing. * * Otherwise the list_lock will synchronize with * other processors updating the list of slabs. */ spin_lock_irqsave(&n->list_lock, flags); on_node_partial = slab_test_node_partial(slab); } } } while (!slab_update_freelist(s, slab, prior, counters, head, new.counters, "__slab_free")); if (likely(!n)) { if (likely(was_frozen)) { /* * The list lock was not taken therefore no list * activity can be necessary. */ stat(s, FREE_FROZEN); } else if (kmem_cache_has_cpu_partial(s) && !prior) { /* * If we started with a full slab then put it onto the * per cpu partial list. */ put_cpu_partial(s, slab, 1); stat(s, CPU_PARTIAL_FREE); } return; } /* * This slab was partially empty but not on the per-node partial list, * in which case we shouldn't manipulate its list, just return. */ if (prior && !on_node_partial) { spin_unlock_irqrestore(&n->list_lock, flags); return; } if (unlikely(!new.inuse && n->nr_partial >= s->min_partial)) goto slab_empty; /* * Objects left in the slab. If it was not on the partial list before * then add it. */ if (!kmem_cache_has_cpu_partial(s) && unlikely(!prior)) { add_partial(n, slab, DEACTIVATE_TO_TAIL); stat(s, FREE_ADD_PARTIAL); } spin_unlock_irqrestore(&n->list_lock, flags); return; slab_empty: if (prior) { /* * Slab on the partial list. */ remove_partial(n, slab); stat(s, FREE_REMOVE_PARTIAL); } spin_unlock_irqrestore(&n->list_lock, flags); stat(s, FREE_SLAB); discard_slab(s, slab); } #ifndef CONFIG_SLUB_TINY /* * Fastpath with forced inlining to produce a kfree and kmem_cache_free that * can perform fastpath freeing without additional function calls. * * The fastpath is only possible if we are freeing to the current cpu slab * of this processor. This typically the case if we have just allocated * the item before. * * If fastpath is not possible then fall back to __slab_free where we deal * with all sorts of special processing. * * Bulk free of a freelist with several objects (all pointing to the * same slab) possible by specifying head and tail ptr, plus objects * count (cnt). Bulk free indicated by tail pointer being set. */ static __always_inline void do_slab_free(struct kmem_cache *s, struct slab *slab, void *head, void *tail, int cnt, unsigned long addr) { struct kmem_cache_cpu *c; unsigned long tid; void **freelist; redo: /* * Determine the currently cpus per cpu slab. * The cpu may change afterward. However that does not matter since * data is retrieved via this pointer. If we are on the same cpu * during the cmpxchg then the free will succeed. */ c = raw_cpu_ptr(s->cpu_slab); tid = READ_ONCE(c->tid); /* Same with comment on barrier() in slab_alloc_node() */ barrier(); if (unlikely(slab != c->slab)) { __slab_free(s, slab, head, tail, cnt, addr); return; } if (USE_LOCKLESS_FAST_PATH()) { freelist = READ_ONCE(c->freelist); set_freepointer(s, tail, freelist); if (unlikely(!__update_cpu_freelist_fast(s, freelist, head, tid))) { note_cmpxchg_failure("slab_free", s, tid); goto redo; } } else { /* Update the free list under the local lock */ local_lock(&s->cpu_slab->lock); c = this_cpu_ptr(s->cpu_slab); if (unlikely(slab != c->slab)) { local_unlock(&s->cpu_slab->lock); goto redo; } tid = c->tid; freelist = c->freelist; set_freepointer(s, tail, freelist); c->freelist = head; c->tid = next_tid(tid); local_unlock(&s->cpu_slab->lock); } stat_add(s, FREE_FASTPATH, cnt); } #else /* CONFIG_SLUB_TINY */ static void do_slab_free(struct kmem_cache *s, struct slab *slab, void *head, void *tail, int cnt, unsigned long addr) { __slab_free(s, slab, head, tail, cnt, addr); } #endif /* CONFIG_SLUB_TINY */ static __fastpath_inline void slab_free(struct kmem_cache *s, struct slab *slab, void *object, unsigned long addr) { memcg_slab_free_hook(s, slab, &object, 1); if (likely(slab_free_hook(s, object, slab_want_init_on_free(s)))) do_slab_free(s, slab, object, object, 1, addr); } static __fastpath_inline void slab_free_bulk(struct kmem_cache *s, struct slab *slab, void *head, void *tail, void **p, int cnt, unsigned long addr) { memcg_slab_free_hook(s, slab, p, cnt); /* * With KASAN enabled slab_free_freelist_hook modifies the freelist * to remove objects, whose reuse must be delayed. */ if (likely(slab_free_freelist_hook(s, &head, &tail, &cnt))) do_slab_free(s, slab, head, tail, cnt, addr); } #ifdef CONFIG_KASAN_GENERIC void ___cache_free(struct kmem_cache *cache, void *x, unsigned long addr) { do_slab_free(cache, virt_to_slab(x), x, x, 1, addr); } #endif static inline struct kmem_cache *virt_to_cache(const void *obj) { struct slab *slab; slab = virt_to_slab(obj); if (WARN_ONCE(!slab, "%s: Object is not a Slab page!\n", __func__)) return NULL; return slab->slab_cache; } static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x) { struct kmem_cache *cachep; if (!IS_ENABLED(CONFIG_SLAB_FREELIST_HARDENED) && !kmem_cache_debug_flags(s, SLAB_CONSISTENCY_CHECKS)) return s; cachep = virt_to_cache(x); if (WARN(cachep && cachep != s, "%s: Wrong slab cache. %s but object is from %s\n", __func__, s->name, cachep->name)) print_tracking(cachep, x); return cachep; } /** * kmem_cache_free - Deallocate an object * @s: The cache the allocation was from. * @x: The previously allocated object. * * Free an object which was previously allocated from this * cache. */ void kmem_cache_free(struct kmem_cache *s, void *x) { s = cache_from_obj(s, x); if (!s) return; trace_kmem_cache_free(_RET_IP_, x, s); slab_free(s, virt_to_slab(x), x, _RET_IP_); } EXPORT_SYMBOL(kmem_cache_free); static void free_large_kmalloc(struct folio *folio, void *object) { unsigned int order = folio_order(folio); if (WARN_ON_ONCE(order == 0)) pr_warn_once("object pointer: 0x%p\n", object); kmemleak_free(object); kasan_kfree_large(object); kmsan_kfree_large(object); lruvec_stat_mod_folio(folio, NR_SLAB_UNRECLAIMABLE_B, -(PAGE_SIZE << order)); folio_put(folio); } /** * kfree - free previously allocated memory * @object: pointer returned by kmalloc() or kmem_cache_alloc() * * If @object is NULL, no operation is performed. */ void kfree(const void *object) { struct folio *folio; struct slab *slab; struct kmem_cache *s; void *x = (void *)object; trace_kfree(_RET_IP_, object); if (unlikely(ZERO_OR_NULL_PTR(object))) return; folio = virt_to_folio(object); if (unlikely(!folio_test_slab(folio))) { free_large_kmalloc(folio, (void *)object); return; } slab = folio_slab(folio); s = slab->slab_cache; slab_free(s, slab, x, _RET_IP_); } EXPORT_SYMBOL(kfree); struct detached_freelist { struct slab *slab; void *tail; void *freelist; int cnt; struct kmem_cache *s; }; /* * This function progressively scans the array with free objects (with * a limited look ahead) and extract objects belonging to the same * slab. It builds a detached freelist directly within the given * slab/objects. This can happen without any need for * synchronization, because the objects are owned by running process. * The freelist is build up as a single linked list in the objects. * The idea is, that this detached freelist can then be bulk * transferred to the real freelist(s), but only requiring a single * synchronization primitive. Look ahead in the array is limited due * to performance reasons. */ static inline int build_detached_freelist(struct kmem_cache *s, size_t size, void **p, struct detached_freelist *df) { int lookahead = 3; void *object; struct folio *folio; size_t same; object = p[--size]; folio = virt_to_folio(object); if (!s) { /* Handle kalloc'ed objects */ if (unlikely(!folio_test_slab(folio))) { free_large_kmalloc(folio, object); df->slab = NULL; return size; } /* Derive kmem_cache from object */ df->slab = folio_slab(folio); df->s = df->slab->slab_cache; } else { df->slab = folio_slab(folio); df->s = cache_from_obj(s, object); /* Support for memcg */ } /* Start new detached freelist */ df->tail = object; df->freelist = object; df->cnt = 1; if (is_kfence_address(object)) return size; set_freepointer(df->s, object, NULL); same = size; while (size) { object = p[--size]; /* df->slab is always set at this point */ if (df->slab == virt_to_slab(object)) { /* Opportunity build freelist */ set_freepointer(df->s, object, df->freelist); df->freelist = object; df->cnt++; same--; if (size != same) swap(p[size], p[same]); continue; } /* Limit look ahead search */ if (!--lookahead) break; } return same; } /* * Internal bulk free of objects that were not initialised by the post alloc * hooks and thus should not be processed by the free hooks */ static void __kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p) { if (!size) return; do { struct detached_freelist df; size = build_detached_freelist(s, size, p, &df); if (!df.slab) continue; do_slab_free(df.s, df.slab, df.freelist, df.tail, df.cnt, _RET_IP_); } while (likely(size)); } /* Note that interrupts must be enabled when calling this function. */ void kmem_cache_free_bulk(struct kmem_cache *s, size_t size, void **p) { if (!size) return; do { struct detached_freelist df; size = build_detached_freelist(s, size, p, &df); if (!df.slab) continue; slab_free_bulk(df.s, df.slab, df.freelist, df.tail, &p[size], df.cnt, _RET_IP_); } while (likely(size)); } EXPORT_SYMBOL(kmem_cache_free_bulk); #ifndef CONFIG_SLUB_TINY static inline int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, void **p) { struct kmem_cache_cpu *c; unsigned long irqflags; int i; /* * Drain objects in the per cpu slab, while disabling local * IRQs, which protects against PREEMPT and interrupts * handlers invoking normal fastpath. */ c = slub_get_cpu_ptr(s->cpu_slab); local_lock_irqsave(&s->cpu_slab->lock, irqflags); for (i = 0; i < size; i++) { void *object = kfence_alloc(s, s->object_size, flags); if (unlikely(object)) { p[i] = object; continue; } object = c->freelist; if (unlikely(!object)) { /* * We may have removed an object from c->freelist using * the fastpath in the previous iteration; in that case, * c->tid has not been bumped yet. * Since ___slab_alloc() may reenable interrupts while * allocating memory, we should bump c->tid now. */ c->tid = next_tid(c->tid); local_unlock_irqrestore(&s->cpu_slab->lock, irqflags); /* * Invoking slow path likely have side-effect * of re-populating per CPU c->freelist */ p[i] = ___slab_alloc(s, flags, NUMA_NO_NODE, _RET_IP_, c, s->object_size); if (unlikely(!p[i])) goto error; c = this_cpu_ptr(s->cpu_slab); maybe_wipe_obj_freeptr(s, p[i]); local_lock_irqsave(&s->cpu_slab->lock, irqflags); continue; /* goto for-loop */ } c->freelist = get_freepointer(s, object); p[i] = object; maybe_wipe_obj_freeptr(s, p[i]); stat(s, ALLOC_FASTPATH); } c->tid = next_tid(c->tid); local_unlock_irqrestore(&s->cpu_slab->lock, irqflags); slub_put_cpu_ptr(s->cpu_slab); return i; error: slub_put_cpu_ptr(s->cpu_slab); __kmem_cache_free_bulk(s, i, p); return 0; } #else /* CONFIG_SLUB_TINY */ static int __kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, void **p) { int i; for (i = 0; i < size; i++) { void *object = kfence_alloc(s, s->object_size, flags); if (unlikely(object)) { p[i] = object; continue; } p[i] = __slab_alloc_node(s, flags, NUMA_NO_NODE, _RET_IP_, s->object_size); if (unlikely(!p[i])) goto error; maybe_wipe_obj_freeptr(s, p[i]); } return i; error: __kmem_cache_free_bulk(s, i, p); return 0; } #endif /* CONFIG_SLUB_TINY */ /* Note that interrupts must be enabled when calling this function. */ int kmem_cache_alloc_bulk(struct kmem_cache *s, gfp_t flags, size_t size, void **p) { int i; struct obj_cgroup *objcg = NULL; if (!size) return 0; /* memcg and kmem_cache debug support */ s = slab_pre_alloc_hook(s, NULL, &objcg, size, flags); if (unlikely(!s)) return 0; i = __kmem_cache_alloc_bulk(s, flags, size, p); /* * memcg and kmem_cache debug support and memory initialization. * Done outside of the IRQ disabled fastpath loop. */ if (likely(i != 0)) { slab_post_alloc_hook(s, objcg, flags, size, p, slab_want_init_on_alloc(flags, s), s->object_size); } else { memcg_slab_alloc_error_hook(s, size, objcg); } return i; } EXPORT_SYMBOL(kmem_cache_alloc_bulk); /* * Object placement in a slab is made very easy because we always start at * offset 0. If we tune the size of the object to the alignment then we can * get the required alignment by putting one properly sized object after * another. * * Notice that the allocation order determines the sizes of the per cpu * caches. Each processor has always one slab available for allocations. * Increasing the allocation order reduces the number of times that slabs * must be moved on and off the partial lists and is therefore a factor in * locking overhead. */ /* * Minimum / Maximum order of slab pages. This influences locking overhead * and slab fragmentation. A higher order reduces the number of partial slabs * and increases the number of allocations possible without having to * take the list_lock. */ static unsigned int slub_min_order; static unsigned int slub_max_order = IS_ENABLED(CONFIG_SLUB_TINY) ? 1 : PAGE_ALLOC_COSTLY_ORDER; static unsigned int slub_min_objects; /* * Calculate the order of allocation given an slab object size. * * The order of allocation has significant impact on performance and other * system components. Generally order 0 allocations should be preferred since * order 0 does not cause fragmentation in the page allocator. Larger objects * be problematic to put into order 0 slabs because there may be too much * unused space left. We go to a higher order if more than 1/16th of the slab * would be wasted. * * In order to reach satisfactory performance we must ensure that a minimum * number of objects is in one slab. Otherwise we may generate too much * activity on the partial lists which requires taking the list_lock. This is * less a concern for large slabs though which are rarely used. * * slab_max_order specifies the order where we begin to stop considering the * number of objects in a slab as critical. If we reach slab_max_order then * we try to keep the page order as low as possible. So we accept more waste * of space in favor of a small page order. * * Higher order allocations also allow the placement of more objects in a * slab and thereby reduce object handling overhead. If the user has * requested a higher minimum order then we start with that one instead of * the smallest order which will fit the object. */ static inline unsigned int calc_slab_order(unsigned int size, unsigned int min_order, unsigned int max_order, unsigned int fract_leftover) { unsigned int order; for (order = min_order; order <= max_order; order++) { unsigned int slab_size = (unsigned int)PAGE_SIZE << order; unsigned int rem; rem = slab_size % size; if (rem <= slab_size / fract_leftover) break; } return order; } static inline int calculate_order(unsigned int size) { unsigned int order; unsigned int min_objects; unsigned int max_objects; unsigned int min_order; min_objects = slub_min_objects; if (!min_objects) { /* * Some architectures will only update present cpus when * onlining them, so don't trust the number if it's just 1. But * we also don't want to use nr_cpu_ids always, as on some other * architectures, there can be many possible cpus, but never * onlined. Here we compromise between trying to avoid too high * order on systems that appear larger than they are, and too * low order on systems that appear smaller than they are. */ unsigned int nr_cpus = num_present_cpus(); if (nr_cpus <= 1) nr_cpus = nr_cpu_ids; min_objects = 4 * (fls(nr_cpus) + 1); } /* min_objects can't be 0 because get_order(0) is undefined */ max_objects = max(order_objects(slub_max_order, size), 1U); min_objects = min(min_objects, max_objects); min_order = max_t(unsigned int, slub_min_order, get_order(min_objects * size)); if (order_objects(min_order, size) > MAX_OBJS_PER_PAGE) return get_order(size * MAX_OBJS_PER_PAGE) - 1; /* * Attempt to find best configuration for a slab. This works by first * attempting to generate a layout with the best possible configuration * and backing off gradually. * * We start with accepting at most 1/16 waste and try to find the * smallest order from min_objects-derived/slab_min_order up to * slab_max_order that will satisfy the constraint. Note that increasing * the order can only result in same or less fractional waste, not more. * * If that fails, we increase the acceptable fraction of waste and try * again. The last iteration with fraction of 1/2 would effectively * accept any waste and give us the order determined by min_objects, as * long as at least single object fits within slab_max_order. */ for (unsigned int fraction = 16; fraction > 1; fraction /= 2) { order = calc_slab_order(size, min_order, slub_max_order, fraction); if (order <= slub_max_order) return order; } /* * Doh this slab cannot be placed using slab_max_order. */ order = get_order(size); if (order <= MAX_PAGE_ORDER) return order; return -ENOSYS; } static void init_kmem_cache_node(struct kmem_cache_node *n) { n->nr_partial = 0; spin_lock_init(&n->list_lock); INIT_LIST_HEAD(&n->partial); #ifdef CONFIG_SLUB_DEBUG atomic_long_set(&n->nr_slabs, 0); atomic_long_set(&n->total_objects, 0); INIT_LIST_HEAD(&n->full); #endif } #ifndef CONFIG_SLUB_TINY static inline int alloc_kmem_cache_cpus(struct kmem_cache *s) { BUILD_BUG_ON(PERCPU_DYNAMIC_EARLY_SIZE < NR_KMALLOC_TYPES * KMALLOC_SHIFT_HIGH * sizeof(struct kmem_cache_cpu)); /* * Must align to double word boundary for the double cmpxchg * instructions to work; see __pcpu_double_call_return_bool(). */ s->cpu_slab = __alloc_percpu(sizeof(struct kmem_cache_cpu), 2 * sizeof(void *)); if (!s->cpu_slab) return 0; init_kmem_cache_cpus(s); return 1; } #else static inline int alloc_kmem_cache_cpus(struct kmem_cache *s) { return 1; } #endif /* CONFIG_SLUB_TINY */ static struct kmem_cache *kmem_cache_node; /* * No kmalloc_node yet so do it by hand. We know that this is the first * slab on the node for this slabcache. There are no concurrent accesses * possible. * * Note that this function only works on the kmem_cache_node * when allocating for the kmem_cache_node. This is used for bootstrapping * memory on a fresh node that has no slab structures yet. */ static void early_kmem_cache_node_alloc(int node) { struct slab *slab; struct kmem_cache_node *n; BUG_ON(kmem_cache_node->size < sizeof(struct kmem_cache_node)); slab = new_slab(kmem_cache_node, GFP_NOWAIT, node); BUG_ON(!slab); if (slab_nid(slab) != node) { pr_err("SLUB: Unable to allocate memory from node %d\n", node); pr_err("SLUB: Allocating a useless per node structure in order to be able to continue\n"); } n = slab->freelist; BUG_ON(!n); #ifdef CONFIG_SLUB_DEBUG init_object(kmem_cache_node, n, SLUB_RED_ACTIVE); init_tracking(kmem_cache_node, n); #endif n = kasan_slab_alloc(kmem_cache_node, n, GFP_KERNEL, false); slab->freelist = get_freepointer(kmem_cache_node, n); slab->inuse = 1; kmem_cache_node->node[node] = n; init_kmem_cache_node(n); inc_slabs_node(kmem_cache_node, node, slab->objects); /* * No locks need to be taken here as it has just been * initialized and there is no concurrent access. */ __add_partial(n, slab, DEACTIVATE_TO_HEAD); } static void free_kmem_cache_nodes(struct kmem_cache *s) { int node; struct kmem_cache_node *n; for_each_kmem_cache_node(s, node, n) { s->node[node] = NULL; kmem_cache_free(kmem_cache_node, n); } } void __kmem_cache_release(struct kmem_cache *s) { cache_random_seq_destroy(s); #ifndef CONFIG_SLUB_TINY free_percpu(s->cpu_slab); #endif free_kmem_cache_nodes(s); } static int init_kmem_cache_nodes(struct kmem_cache *s) { int node; for_each_node_mask(node, slab_nodes) { struct kmem_cache_node *n; if (slab_state == DOWN) { early_kmem_cache_node_alloc(node); continue; } n = kmem_cache_alloc_node(kmem_cache_node, GFP_KERNEL, node); if (!n) { free_kmem_cache_nodes(s); return 0; } init_kmem_cache_node(n); s->node[node] = n; } return 1; } static void set_cpu_partial(struct kmem_cache *s) { #ifdef CONFIG_SLUB_CPU_PARTIAL unsigned int nr_objects; /* * cpu_partial determined the maximum number of objects kept in the * per cpu partial lists of a processor. * * Per cpu partial lists mainly contain slabs that just have one * object freed. If they are used for allocation then they can be * filled up again with minimal effort. The slab will never hit the * per node partial lists and therefore no locking will be required. * * For backwards compatibility reasons, this is determined as number * of objects, even though we now limit maximum number of pages, see * slub_set_cpu_partial() */ if (!kmem_cache_has_cpu_partial(s)) nr_objects = 0; else if (s->size >= PAGE_SIZE) nr_objects = 6; else if (s->size >= 1024) nr_objects = 24; else if (s->size >= 256) nr_objects = 52; else nr_objects = 120; slub_set_cpu_partial(s, nr_objects); #endif } /* * calculate_sizes() determines the order and the distribution of data within * a slab object. */ static int calculate_sizes(struct kmem_cache *s) { slab_flags_t flags = s->flags; unsigned int size = s->object_size; unsigned int order; /* * Round up object size to the next word boundary. We can only * place the free pointer at word boundaries and this determines * the possible location of the free pointer. */ size = ALIGN(size, sizeof(void *)); #ifdef CONFIG_SLUB_DEBUG /* * Determine if we can poison the object itself. If the user of * the slab may touch the object after free or before allocation * then we should never poison the object itself. */ if ((flags & SLAB_POISON) && !(flags & SLAB_TYPESAFE_BY_RCU) && !s->ctor) s->flags |= __OBJECT_POISON; else s->flags &= ~__OBJECT_POISON; /* * If we are Redzoning then check if there is some space between the * end of the object and the free pointer. If not then add an * additional word to have some bytes to store Redzone information. */ if ((flags & SLAB_RED_ZONE) && size == s->object_size) size += sizeof(void *); #endif /* * With that we have determined the number of bytes in actual use * by the object and redzoning. */ s->inuse = size; if (slub_debug_orig_size(s) || (flags & (SLAB_TYPESAFE_BY_RCU | SLAB_POISON)) || ((flags & SLAB_RED_ZONE) && s->object_size < sizeof(void *)) || s->ctor) { /* * Relocate free pointer after the object if it is not * permitted to overwrite the first word of the object on * kmem_cache_free. * * This is the case if we do RCU, have a constructor or * destructor, are poisoning the objects, or are * redzoning an object smaller than sizeof(void *). * * The assumption that s->offset >= s->inuse means free * pointer is outside of the object is used in the * freeptr_outside_object() function. If that is no * longer true, the function needs to be modified. */ s->offset = size; size += sizeof(void *); } else { /* * Store freelist pointer near middle of object to keep * it away from the edges of the object to avoid small * sized over/underflows from neighboring allocations. */ s->offset = ALIGN_DOWN(s->object_size / 2, sizeof(void *)); } #ifdef CONFIG_SLUB_DEBUG if (flags & SLAB_STORE_USER) { /* * Need to store information about allocs and frees after * the object. */ size += 2 * sizeof(struct track); /* Save the original kmalloc request size */ if (flags & SLAB_KMALLOC) size += sizeof(unsigned int); } #endif kasan_cache_create(s, &size, &s->flags); #ifdef CONFIG_SLUB_DEBUG if (flags & SLAB_RED_ZONE) { /* * Add some empty padding so that we can catch * overwrites from earlier objects rather than let * tracking information or the free pointer be * corrupted if a user writes before the start * of the object. */ size += sizeof(void *); s->red_left_pad = sizeof(void *); s->red_left_pad = ALIGN(s->red_left_pad, s->align); size += s->red_left_pad; } #endif /* * SLUB stores one object immediately after another beginning from * offset 0. In order to align the objects we have to simply size * each object to conform to the alignment. */ size = ALIGN(size, s->align); s->size = size; s->reciprocal_size = reciprocal_value(size); order = calculate_order(size); if ((int)order < 0) return 0; s->allocflags = 0; if (order) s->allocflags |= __GFP_COMP; if (s->flags & SLAB_CACHE_DMA) s->allocflags |= GFP_DMA; if (s->flags & SLAB_CACHE_DMA32) s->allocflags |= GFP_DMA32; if (s->flags & SLAB_RECLAIM_ACCOUNT) s->allocflags |= __GFP_RECLAIMABLE; /* * Determine the number of objects per slab */ s->oo = oo_make(order, size); s->min = oo_make(get_order(size), size); return !!oo_objects(s->oo); } static int kmem_cache_open(struct kmem_cache *s, slab_flags_t flags) { s->flags = kmem_cache_flags(flags, s->name); #ifdef CONFIG_SLAB_FREELIST_HARDENED s->random = get_random_long(); #endif if (!calculate_sizes(s)) goto error; if (disable_higher_order_debug) { /* * Disable debugging flags that store metadata if the min slab * order increased. */ if (get_order(s->size) > get_order(s->object_size)) { s->flags &= ~DEBUG_METADATA_FLAGS; s->offset = 0; if (!calculate_sizes(s)) goto error; } } #ifdef system_has_freelist_aba if (system_has_freelist_aba() && !(s->flags & SLAB_NO_CMPXCHG)) { /* Enable fast mode */ s->flags |= __CMPXCHG_DOUBLE; } #endif /* * The larger the object size is, the more slabs we want on the partial * list to avoid pounding the page allocator excessively. */ s->min_partial = min_t(unsigned long, MAX_PARTIAL, ilog2(s->size) / 2); s->min_partial = max_t(unsigned long, MIN_PARTIAL, s->min_partial); set_cpu_partial(s); #ifdef CONFIG_NUMA s->remote_node_defrag_ratio = 1000; #endif /* Initialize the pre-computed randomized freelist if slab is up */ if (slab_state >= UP) { if (init_cache_random_seq(s)) goto error; } if (!init_kmem_cache_nodes(s)) goto error; if (alloc_kmem_cache_cpus(s)) return 0; error: __kmem_cache_release(s); return -EINVAL; } static void list_slab_objects(struct kmem_cache *s, struct slab *slab, const char *text) { #ifdef CONFIG_SLUB_DEBUG void *addr = slab_address(slab); void *p; slab_err(s, slab, text, s->name); spin_lock(&object_map_lock); __fill_map(object_map, s, slab); for_each_object(p, s, addr, slab->objects) { if (!test_bit(__obj_to_index(s, addr, p), object_map)) { pr_err("Object 0x%p @offset=%tu\n", p, p - addr); print_tracking(s, p); } } spin_unlock(&object_map_lock); #endif } /* * Attempt to free all partial slabs on a node. * This is called from __kmem_cache_shutdown(). We must take list_lock * because sysfs file might still access partial list after the shutdowning. */ static void free_partial(struct kmem_cache *s, struct kmem_cache_node *n) { LIST_HEAD(discard); struct slab *slab, *h; BUG_ON(irqs_disabled()); spin_lock_irq(&n->list_lock); list_for_each_entry_safe(slab, h, &n->partial, slab_list) { if (!slab->inuse) { remove_partial(n, slab); list_add(&slab->slab_list, &discard); } else { list_slab_objects(s, slab, "Objects remaining in %s on __kmem_cache_shutdown()"); } } spin_unlock_irq(&n->list_lock); list_for_each_entry_safe(slab, h, &discard, slab_list) discard_slab(s, slab); } bool __kmem_cache_empty(struct kmem_cache *s) { int node; struct kmem_cache_node *n; for_each_kmem_cache_node(s, node, n) if (n->nr_partial || node_nr_slabs(n)) return false; return true; } /* * Release all resources used by a slab cache. */ int __kmem_cache_shutdown(struct kmem_cache *s) { int node; struct kmem_cache_node *n; flush_all_cpus_locked(s); /* Attempt to free all objects */ for_each_kmem_cache_node(s, node, n) { free_partial(s, n); if (n->nr_partial || node_nr_slabs(n)) return 1; } return 0; } #ifdef CONFIG_PRINTK void __kmem_obj_info(struct kmem_obj_info *kpp, void *object, struct slab *slab) { void *base; int __maybe_unused i; unsigned int objnr; void *objp; void *objp0; struct kmem_cache *s = slab->slab_cache; struct track __maybe_unused *trackp; kpp->kp_ptr = object; kpp->kp_slab = slab; kpp->kp_slab_cache = s; base = slab_address(slab); objp0 = kasan_reset_tag(object); #ifdef CONFIG_SLUB_DEBUG objp = restore_red_left(s, objp0); #else objp = objp0; #endif objnr = obj_to_index(s, slab, objp); kpp->kp_data_offset = (unsigned long)((char *)objp0 - (char *)objp); objp = base + s->size * objnr; kpp->kp_objp = objp; if (WARN_ON_ONCE(objp < base || objp >= base + slab->objects * s->size || (objp - base) % s->size) || !(s->flags & SLAB_STORE_USER)) return; #ifdef CONFIG_SLUB_DEBUG objp = fixup_red_left(s, objp); trackp = get_track(s, objp, TRACK_ALLOC); kpp->kp_ret = (void *)trackp->addr; #ifdef CONFIG_STACKDEPOT { depot_stack_handle_t handle; unsigned long *entries; unsigned int nr_entries; handle = READ_ONCE(trackp->handle); if (handle) { nr_entries = stack_depot_fetch(handle, &entries); for (i = 0; i < KS_ADDRS_COUNT && i < nr_entries; i++) kpp->kp_stack[i] = (void *)entries[i]; } trackp = get_track(s, objp, TRACK_FREE); handle = READ_ONCE(trackp->handle); if (handle) { nr_entries = stack_depot_fetch(handle, &entries); for (i = 0; i < KS_ADDRS_COUNT && i < nr_entries; i++) kpp->kp_free_stack[i] = (void *)entries[i]; } } #endif #endif } #endif /******************************************************************** * Kmalloc subsystem *******************************************************************/ static int __init setup_slub_min_order(char *str) { get_option(&str, (int *)&slub_min_order); if (slub_min_order > slub_max_order) slub_max_order = slub_min_order; return 1; } __setup("slab_min_order=", setup_slub_min_order); __setup_param("slub_min_order=", slub_min_order, setup_slub_min_order, 0); static int __init setup_slub_max_order(char *str) { get_option(&str, (int *)&slub_max_order); slub_max_order = min_t(unsigned int, slub_max_order, MAX_PAGE_ORDER); if (slub_min_order > slub_max_order) slub_min_order = slub_max_order; return 1; } __setup("slab_max_order=", setup_slub_max_order); __setup_param("slub_max_order=", slub_max_order, setup_slub_max_order, 0); static int __init setup_slub_min_objects(char *str) { get_option(&str, (int *)&slub_min_objects); return 1; } __setup("slab_min_objects=", setup_slub_min_objects); __setup_param("slub_min_objects=", slub_min_objects, setup_slub_min_objects, 0); #ifdef CONFIG_HARDENED_USERCOPY /* * Rejects incorrectly sized objects and objects that are to be copied * to/from userspace but do not fall entirely within the containing slab * cache's usercopy region. * * Returns NULL if check passes, otherwise const char * to name of cache * to indicate an error. */ void __check_heap_object(const void *ptr, unsigned long n, const struct slab *slab, bool to_user) { struct kmem_cache *s; unsigned int offset; bool is_kfence = is_kfence_address(ptr); ptr = kasan_reset_tag(ptr); /* Find object and usable object size. */ s = slab->slab_cache; /* Reject impossible pointers. */ if (ptr < slab_address(slab)) usercopy_abort("SLUB object not in SLUB page?!", NULL, to_user, 0, n); /* Find offset within object. */ if (is_kfence) offset = ptr - kfence_object_start(ptr); else offset = (ptr - slab_address(slab)) % s->size; /* Adjust for redzone and reject if within the redzone. */ if (!is_kfence && kmem_cache_debug_flags(s, SLAB_RED_ZONE)) { if (offset < s->red_left_pad) usercopy_abort("SLUB object in left red zone", s->name, to_user, offset, n); offset -= s->red_left_pad; } /* Allow address range falling entirely within usercopy region. */ if (offset >= s->useroffset && offset - s->useroffset <= s->usersize && n <= s->useroffset - offset + s->usersize) return; usercopy_abort("SLUB object", s->name, to_user, offset, n); } #endif /* CONFIG_HARDENED_USERCOPY */ #define SHRINK_PROMOTE_MAX 32 /* * kmem_cache_shrink discards empty slabs and promotes the slabs filled * up most to the head of the partial lists. New allocations will then * fill those up and thus they can be removed from the partial lists. * * The slabs with the least items are placed last. This results in them * being allocated from last increasing the chance that the last objects * are freed in them. */ static int __kmem_cache_do_shrink(struct kmem_cache *s) { int node; int i; struct kmem_cache_node *n; struct slab *slab; struct slab *t; struct list_head discard; struct list_head promote[SHRINK_PROMOTE_MAX]; unsigned long flags; int ret = 0; for_each_kmem_cache_node(s, node, n) { INIT_LIST_HEAD(&discard); for (i = 0; i < SHRINK_PROMOTE_MAX; i++) INIT_LIST_HEAD(promote + i); spin_lock_irqsave(&n->list_lock, flags); /* * Build lists of slabs to discard or promote. * * Note that concurrent frees may occur while we hold the * list_lock. slab->inuse here is the upper limit. */ list_for_each_entry_safe(slab, t, &n->partial, slab_list) { int free = slab->objects - slab->inuse; /* Do not reread slab->inuse */ barrier(); /* We do not keep full slabs on the list */ BUG_ON(free <= 0); if (free == slab->objects) { list_move(&slab->slab_list, &discard); slab_clear_node_partial(slab); n->nr_partial--; dec_slabs_node(s, node, slab->objects); } else if (free <= SHRINK_PROMOTE_MAX) list_move(&slab->slab_list, promote + free - 1); } /* * Promote the slabs filled up most to the head of the * partial list. */ for (i = SHRINK_PROMOTE_MAX - 1; i >= 0; i--) list_splice(promote + i, &n->partial); spin_unlock_irqrestore(&n->list_lock, flags); /* Release empty slabs */ list_for_each_entry_safe(slab, t, &discard, slab_list) free_slab(s, slab); if (node_nr_slabs(n)) ret = 1; } return ret; } int __kmem_cache_shrink(struct kmem_cache *s) { flush_all(s); return __kmem_cache_do_shrink(s); } static int slab_mem_going_offline_callback(void *arg) { struct kmem_cache *s; mutex_lock(&slab_mutex); list_for_each_entry(s, &slab_caches, list) { flush_all_cpus_locked(s); __kmem_cache_do_shrink(s); } mutex_unlock(&slab_mutex); return 0; } static void slab_mem_offline_callback(void *arg) { struct memory_notify *marg = arg; int offline_node; offline_node = marg->status_change_nid_normal; /* * If the node still has available memory. we need kmem_cache_node * for it yet. */ if (offline_node < 0) return; mutex_lock(&slab_mutex); node_clear(offline_node, slab_nodes); /* * We no longer free kmem_cache_node structures here, as it would be * racy with all get_node() users, and infeasible to protect them with * slab_mutex. */ mutex_unlock(&slab_mutex); } static int slab_mem_going_online_callback(void *arg) { struct kmem_cache_node *n; struct kmem_cache *s; struct memory_notify *marg = arg; int nid = marg->status_change_nid_normal; int ret = 0; /* * If the node's memory is already available, then kmem_cache_node is * already created. Nothing to do. */ if (nid < 0) return 0; /* * We are bringing a node online. No memory is available yet. We must * allocate a kmem_cache_node structure in order to bring the node * online. */ mutex_lock(&slab_mutex); list_for_each_entry(s, &slab_caches, list) { /* * The structure may already exist if the node was previously * onlined and offlined. */ if (get_node(s, nid)) continue; /* * XXX: kmem_cache_alloc_node will fallback to other nodes * since memory is not yet available from the node that * is brought up. */ n = kmem_cache_alloc(kmem_cache_node, GFP_KERNEL); if (!n) { ret = -ENOMEM; goto out; } init_kmem_cache_node(n); s->node[nid] = n; } /* * Any cache created after this point will also have kmem_cache_node * initialized for the new node. */ node_set(nid, slab_nodes); out: mutex_unlock(&slab_mutex); return ret; } static int slab_memory_callback(struct notifier_block *self, unsigned long action, void *arg) { int ret = 0; switch (action) { case MEM_GOING_ONLINE: ret = slab_mem_going_online_callback(arg); break; case MEM_GOING_OFFLINE: ret = slab_mem_going_offline_callback(arg); break; case MEM_OFFLINE: case MEM_CANCEL_ONLINE: slab_mem_offline_callback(arg); break; case MEM_ONLINE: case MEM_CANCEL_OFFLINE: break; } if (ret) ret = notifier_from_errno(ret); else ret = NOTIFY_OK; return ret; } /******************************************************************** * Basic setup of slabs *******************************************************************/ /* * Used for early kmem_cache structures that were allocated using * the page allocator. Allocate them properly then fix up the pointers * that may be pointing to the wrong kmem_cache structure. */ static struct kmem_cache * __init bootstrap(struct kmem_cache *static_cache) { int node; struct kmem_cache *s = kmem_cache_zalloc(kmem_cache, GFP_NOWAIT); struct kmem_cache_node *n; memcpy(s, static_cache, kmem_cache->object_size); /* * This runs very early, and only the boot processor is supposed to be * up. Even if it weren't true, IRQs are not up so we couldn't fire * IPIs around. */ __flush_cpu_slab(s, smp_processor_id()); for_each_kmem_cache_node(s, node, n) { struct slab *p; list_for_each_entry(p, &n->partial, slab_list) p->slab_cache = s; #ifdef CONFIG_SLUB_DEBUG list_for_each_entry(p, &n->full, slab_list) p->slab_cache = s; #endif } list_add(&s->list, &slab_caches); return s; } void __init kmem_cache_init(void) { static __initdata struct kmem_cache boot_kmem_cache, boot_kmem_cache_node; int node; if (debug_guardpage_minorder()) slub_max_order = 0; /* Print slub debugging pointers without hashing */ if (__slub_debug_enabled()) no_hash_pointers_enable(NULL); kmem_cache_node = &boot_kmem_cache_node; kmem_cache = &boot_kmem_cache; /* * Initialize the nodemask for which we will allocate per node * structures. Here we don't need taking slab_mutex yet. */ for_each_node_state(node, N_NORMAL_MEMORY) node_set(node, slab_nodes); create_boot_cache(kmem_cache_node, "kmem_cache_node", sizeof(struct kmem_cache_node), SLAB_HWCACHE_ALIGN, 0, 0); hotplug_memory_notifier(slab_memory_callback, SLAB_CALLBACK_PRI); /* Able to allocate the per node structures */ slab_state = PARTIAL; create_boot_cache(kmem_cache, "kmem_cache", offsetof(struct kmem_cache, node) + nr_node_ids * sizeof(struct kmem_cache_node *), SLAB_HWCACHE_ALIGN, 0, 0); kmem_cache = bootstrap(&boot_kmem_cache); kmem_cache_node = bootstrap(&boot_kmem_cache_node); /* Now we can use the kmem_cache to allocate kmalloc slabs */ setup_kmalloc_cache_index_table(); create_kmalloc_caches(); /* Setup random freelists for each cache */ init_freelist_randomization(); cpuhp_setup_state_nocalls(CPUHP_SLUB_DEAD, "slub:dead", NULL, slub_cpu_dead); pr_info("SLUB: HWalign=%d, Order=%u-%u, MinObjects=%u, CPUs=%u, Nodes=%u\n", cache_line_size(), slub_min_order, slub_max_order, slub_min_objects, nr_cpu_ids, nr_node_ids); } void __init kmem_cache_init_late(void) { #ifndef CONFIG_SLUB_TINY flushwq = alloc_workqueue("slub_flushwq", WQ_MEM_RECLAIM, 0); WARN_ON(!flushwq); #endif } struct kmem_cache * __kmem_cache_alias(const char *name, unsigned int size, unsigned int align, slab_flags_t flags, void (*ctor)(void *)) { struct kmem_cache *s; s = find_mergeable(size, align, flags, name, ctor); if (s) { if (sysfs_slab_alias(s, name)) return NULL; s->refcount++; /* * Adjust the object sizes so that we clear * the complete object on kzalloc. */ s->object_size = max(s->object_size, size); s->inuse = max(s->inuse, ALIGN(size, sizeof(void *))); } return s; } int __kmem_cache_create(struct kmem_cache *s, slab_flags_t flags) { int err; err = kmem_cache_open(s, flags); if (err) return err; /* Mutex is not taken during early boot */ if (slab_state <= UP) return 0; err = sysfs_slab_add(s); if (err) { __kmem_cache_release(s); return err; } if (s->flags & SLAB_STORE_USER) debugfs_slab_add(s); return 0; } #ifdef SLAB_SUPPORTS_SYSFS static int count_inuse(struct slab *slab) { return slab->inuse; } static int count_total(struct slab *slab) { return slab->objects; } #endif #ifdef CONFIG_SLUB_DEBUG static void validate_slab(struct kmem_cache *s, struct slab *slab, unsigned long *obj_map) { void *p; void *addr = slab_address(slab); if (!check_slab(s, slab) || !on_freelist(s, slab, NULL)) return; /* Now we know that a valid freelist exists */ __fill_map(obj_map, s, slab); for_each_object(p, s, addr, slab->objects) { u8 val = test_bit(__obj_to_index(s, addr, p), obj_map) ? SLUB_RED_INACTIVE : SLUB_RED_ACTIVE; if (!check_object(s, slab, p, val)) break; } } static int validate_slab_node(struct kmem_cache *s, struct kmem_cache_node *n, unsigned long *obj_map) { unsigned long count = 0; struct slab *slab; unsigned long flags; spin_lock_irqsave(&n->list_lock, flags); list_for_each_entry(slab, &n->partial, slab_list) { validate_slab(s, slab, obj_map); count++; } if (count != n->nr_partial) { pr_err("SLUB %s: %ld partial slabs counted but counter=%ld\n", s->name, count, n->nr_partial); slab_add_kunit_errors(); } if (!(s->flags & SLAB_STORE_USER)) goto out; list_for_each_entry(slab, &n->full, slab_list) { validate_slab(s, slab, obj_map); count++; } if (count != node_nr_slabs(n)) { pr_err("SLUB: %s %ld slabs counted but counter=%ld\n", s->name, count, node_nr_slabs(n)); slab_add_kunit_errors(); } out: spin_unlock_irqrestore(&n->list_lock, flags); return count; } long validate_slab_cache(struct kmem_cache *s) { int node; unsigned long count = 0; struct kmem_cache_node *n; unsigned long *obj_map; obj_map = bitmap_alloc(oo_objects(s->oo), GFP_KERNEL); if (!obj_map) return -ENOMEM; flush_all(s); for_each_kmem_cache_node(s, node, n) count += validate_slab_node(s, n, obj_map); bitmap_free(obj_map); return count; } EXPORT_SYMBOL(validate_slab_cache); #ifdef CONFIG_DEBUG_FS /* * Generate lists of code addresses where slabcache objects are allocated * and freed. */ struct location { depot_stack_handle_t handle; unsigned long count; unsigned long addr; unsigned long waste; long long sum_time; long min_time; long max_time; long min_pid; long max_pid; DECLARE_BITMAP(cpus, NR_CPUS); nodemask_t nodes; }; struct loc_track { unsigned long max; unsigned long count; struct location *loc; loff_t idx; }; static struct dentry *slab_debugfs_root; static void free_loc_track(struct loc_track *t) { if (t->max) free_pages((unsigned long)t->loc, get_order(sizeof(struct location) * t->max)); } static int alloc_loc_track(struct loc_track *t, unsigned long max, gfp_t flags) { struct location *l; int order; order = get_order(sizeof(struct location) * max); l = (void *)__get_free_pages(flags, order); if (!l) return 0; if (t->count) { memcpy(l, t->loc, sizeof(struct location) * t->count); free_loc_track(t); } t->max = max; t->loc = l; return 1; } static int add_location(struct loc_track *t, struct kmem_cache *s, const struct track *track, unsigned int orig_size) { long start, end, pos; struct location *l; unsigned long caddr, chandle, cwaste; unsigned long age = jiffies - track->when; depot_stack_handle_t handle = 0; unsigned int waste = s->object_size - orig_size; #ifdef CONFIG_STACKDEPOT handle = READ_ONCE(track->handle); #endif start = -1; end = t->count; for ( ; ; ) { pos = start + (end - start + 1) / 2; /* * There is nothing at "end". If we end up there * we need to add something to before end. */ if (pos == end) break; l = &t->loc[pos]; caddr = l->addr; chandle = l->handle; cwaste = l->waste; if ((track->addr == caddr) && (handle == chandle) && (waste == cwaste)) { l->count++; if (track->when) { l->sum_time += age; if (age < l->min_time) l->min_time = age; if (age > l->max_time) l->max_time = age; if (track->pid < l->min_pid) l->min_pid = track->pid; if (track->pid > l->max_pid) l->max_pid = track->pid; cpumask_set_cpu(track->cpu, to_cpumask(l->cpus)); } node_set(page_to_nid(virt_to_page(track)), l->nodes); return 1; } if (track->addr < caddr) end = pos; else if (track->addr == caddr && handle < chandle) end = pos; else if (track->addr == caddr && handle == chandle && waste < cwaste) end = pos; else start = pos; } /* * Not found. Insert new tracking element. */ if (t->count >= t->max && !alloc_loc_track(t, 2 * t->max, GFP_ATOMIC)) return 0; l = t->loc + pos; if (pos < t->count) memmove(l + 1, l, (t->count - pos) * sizeof(struct location)); t->count++; l->count = 1; l->addr = track->addr; l->sum_time = age; l->min_time = age; l->max_time = age; l->min_pid = track->pid; l->max_pid = track->pid; l->handle = handle; l->waste = waste; cpumask_clear(to_cpumask(l->cpus)); cpumask_set_cpu(track->cpu, to_cpumask(l->cpus)); nodes_clear(l->nodes); node_set(page_to_nid(virt_to_page(track)), l->nodes); return 1; } static void process_slab(struct loc_track *t, struct kmem_cache *s, struct slab *slab, enum track_item alloc, unsigned long *obj_map) { void *addr = slab_address(slab); bool is_alloc = (alloc == TRACK_ALLOC); void *p; __fill_map(obj_map, s, slab); for_each_object(p, s, addr, slab->objects) if (!test_bit(__obj_to_index(s, addr, p), obj_map)) add_location(t, s, get_track(s, p, alloc), is_alloc ? get_orig_size(s, p) : s->object_size); } #endif /* CONFIG_DEBUG_FS */ #endif /* CONFIG_SLUB_DEBUG */ #ifdef SLAB_SUPPORTS_SYSFS enum slab_stat_type { SL_ALL, /* All slabs */ SL_PARTIAL, /* Only partially allocated slabs */ SL_CPU, /* Only slabs used for cpu caches */ SL_OBJECTS, /* Determine allocated objects not slabs */ SL_TOTAL /* Determine object capacity not slabs */ }; #define SO_ALL (1 << SL_ALL) #define SO_PARTIAL (1 << SL_PARTIAL) #define SO_CPU (1 << SL_CPU) #define SO_OBJECTS (1 << SL_OBJECTS) #define SO_TOTAL (1 << SL_TOTAL) static ssize_t show_slab_objects(struct kmem_cache *s, char *buf, unsigned long flags) { unsigned long total = 0; int node; int x; unsigned long *nodes; int len = 0; nodes = kcalloc(nr_node_ids, sizeof(unsigned long), GFP_KERNEL); if (!nodes) return -ENOMEM; if (flags & SO_CPU) { int cpu; for_each_possible_cpu(cpu) { struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu); int node; struct slab *slab; slab = READ_ONCE(c->slab); if (!slab) continue; node = slab_nid(slab); if (flags & SO_TOTAL) x = slab->objects; else if (flags & SO_OBJECTS) x = slab->inuse; else x = 1; total += x; nodes[node] += x; #ifdef CONFIG_SLUB_CPU_PARTIAL slab = slub_percpu_partial_read_once(c); if (slab) { node = slab_nid(slab); if (flags & SO_TOTAL) WARN_ON_ONCE(1); else if (flags & SO_OBJECTS) WARN_ON_ONCE(1); else x = slab->slabs; total += x; nodes[node] += x; } #endif } } /* * It is impossible to take "mem_hotplug_lock" here with "kernfs_mutex" * already held which will conflict with an existing lock order: * * mem_hotplug_lock->slab_mutex->kernfs_mutex * * We don't really need mem_hotplug_lock (to hold off * slab_mem_going_offline_callback) here because slab's memory hot * unplug code doesn't destroy the kmem_cache->node[] data. */ #ifdef CONFIG_SLUB_DEBUG if (flags & SO_ALL) { struct kmem_cache_node *n; for_each_kmem_cache_node(s, node, n) { if (flags & SO_TOTAL) x = node_nr_objs(n); else if (flags & SO_OBJECTS) x = node_nr_objs(n) - count_partial(n, count_free); else x = node_nr_slabs(n); total += x; nodes[node] += x; } } else #endif if (flags & SO_PARTIAL) { struct kmem_cache_node *n; for_each_kmem_cache_node(s, node, n) { if (flags & SO_TOTAL) x = count_partial(n, count_total); else if (flags & SO_OBJECTS) x = count_partial(n, count_inuse); else x = n->nr_partial; total += x; nodes[node] += x; } } len += sysfs_emit_at(buf, len, "%lu", total); #ifdef CONFIG_NUMA for (node = 0; node < nr_node_ids; node++) { if (nodes[node]) len += sysfs_emit_at(buf, len, " N%d=%lu", node, nodes[node]); } #endif len += sysfs_emit_at(buf, len, "\n"); kfree(nodes); return len; } #define to_slab_attr(n) container_of(n, struct slab_attribute, attr) #define to_slab(n) container_of(n, struct kmem_cache, kobj) struct slab_attribute { struct attribute attr; ssize_t (*show)(struct kmem_cache *s, char *buf); ssize_t (*store)(struct kmem_cache *s, const char *x, size_t count); }; #define SLAB_ATTR_RO(_name) \ static struct slab_attribute _name##_attr = __ATTR_RO_MODE(_name, 0400) #define SLAB_ATTR(_name) \ static struct slab_attribute _name##_attr = __ATTR_RW_MODE(_name, 0600) static ssize_t slab_size_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%u\n", s->size); } SLAB_ATTR_RO(slab_size); static ssize_t align_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%u\n", s->align); } SLAB_ATTR_RO(align); static ssize_t object_size_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%u\n", s->object_size); } SLAB_ATTR_RO(object_size); static ssize_t objs_per_slab_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%u\n", oo_objects(s->oo)); } SLAB_ATTR_RO(objs_per_slab); static ssize_t order_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%u\n", oo_order(s->oo)); } SLAB_ATTR_RO(order); static ssize_t min_partial_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%lu\n", s->min_partial); } static ssize_t min_partial_store(struct kmem_cache *s, const char *buf, size_t length) { unsigned long min; int err; err = kstrtoul(buf, 10, &min); if (err) return err; s->min_partial = min; return length; } SLAB_ATTR(min_partial); static ssize_t cpu_partial_show(struct kmem_cache *s, char *buf) { unsigned int nr_partial = 0; #ifdef CONFIG_SLUB_CPU_PARTIAL nr_partial = s->cpu_partial; #endif return sysfs_emit(buf, "%u\n", nr_partial); } static ssize_t cpu_partial_store(struct kmem_cache *s, const char *buf, size_t length) { unsigned int objects; int err; err = kstrtouint(buf, 10, &objects); if (err) return err; if (objects && !kmem_cache_has_cpu_partial(s)) return -EINVAL; slub_set_cpu_partial(s, objects); flush_all(s); return length; } SLAB_ATTR(cpu_partial); static ssize_t ctor_show(struct kmem_cache *s, char *buf) { if (!s->ctor) return 0; return sysfs_emit(buf, "%pS\n", s->ctor); } SLAB_ATTR_RO(ctor); static ssize_t aliases_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%d\n", s->refcount < 0 ? 0 : s->refcount - 1); } SLAB_ATTR_RO(aliases); static ssize_t partial_show(struct kmem_cache *s, char *buf) { return show_slab_objects(s, buf, SO_PARTIAL); } SLAB_ATTR_RO(partial); static ssize_t cpu_slabs_show(struct kmem_cache *s, char *buf) { return show_slab_objects(s, buf, SO_CPU); } SLAB_ATTR_RO(cpu_slabs); static ssize_t objects_partial_show(struct kmem_cache *s, char *buf) { return show_slab_objects(s, buf, SO_PARTIAL|SO_OBJECTS); } SLAB_ATTR_RO(objects_partial); static ssize_t slabs_cpu_partial_show(struct kmem_cache *s, char *buf) { int objects = 0; int slabs = 0; int cpu __maybe_unused; int len = 0; #ifdef CONFIG_SLUB_CPU_PARTIAL for_each_online_cpu(cpu) { struct slab *slab; slab = slub_percpu_partial(per_cpu_ptr(s->cpu_slab, cpu)); if (slab) slabs += slab->slabs; } #endif /* Approximate half-full slabs, see slub_set_cpu_partial() */ objects = (slabs * oo_objects(s->oo)) / 2; len += sysfs_emit_at(buf, len, "%d(%d)", objects, slabs); #ifdef CONFIG_SLUB_CPU_PARTIAL for_each_online_cpu(cpu) { struct slab *slab; slab = slub_percpu_partial(per_cpu_ptr(s->cpu_slab, cpu)); if (slab) { slabs = READ_ONCE(slab->slabs); objects = (slabs * oo_objects(s->oo)) / 2; len += sysfs_emit_at(buf, len, " C%d=%d(%d)", cpu, objects, slabs); } } #endif len += sysfs_emit_at(buf, len, "\n"); return len; } SLAB_ATTR_RO(slabs_cpu_partial); static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_RECLAIM_ACCOUNT)); } SLAB_ATTR_RO(reclaim_account); static ssize_t hwcache_align_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_HWCACHE_ALIGN)); } SLAB_ATTR_RO(hwcache_align); #ifdef CONFIG_ZONE_DMA static ssize_t cache_dma_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_CACHE_DMA)); } SLAB_ATTR_RO(cache_dma); #endif #ifdef CONFIG_HARDENED_USERCOPY static ssize_t usersize_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%u\n", s->usersize); } SLAB_ATTR_RO(usersize); #endif static ssize_t destroy_by_rcu_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_TYPESAFE_BY_RCU)); } SLAB_ATTR_RO(destroy_by_rcu); #ifdef CONFIG_SLUB_DEBUG static ssize_t slabs_show(struct kmem_cache *s, char *buf) { return show_slab_objects(s, buf, SO_ALL); } SLAB_ATTR_RO(slabs); static ssize_t total_objects_show(struct kmem_cache *s, char *buf) { return show_slab_objects(s, buf, SO_ALL|SO_TOTAL); } SLAB_ATTR_RO(total_objects); static ssize_t objects_show(struct kmem_cache *s, char *buf) { return show_slab_objects(s, buf, SO_ALL|SO_OBJECTS); } SLAB_ATTR_RO(objects); static ssize_t sanity_checks_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_CONSISTENCY_CHECKS)); } SLAB_ATTR_RO(sanity_checks); static ssize_t trace_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_TRACE)); } SLAB_ATTR_RO(trace); static ssize_t red_zone_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_RED_ZONE)); } SLAB_ATTR_RO(red_zone); static ssize_t poison_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_POISON)); } SLAB_ATTR_RO(poison); static ssize_t store_user_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_STORE_USER)); } SLAB_ATTR_RO(store_user); static ssize_t validate_show(struct kmem_cache *s, char *buf) { return 0; } static ssize_t validate_store(struct kmem_cache *s, const char *buf, size_t length) { int ret = -EINVAL; if (buf[0] == '1' && kmem_cache_debug(s)) { ret = validate_slab_cache(s); if (ret >= 0) ret = length; } return ret; } SLAB_ATTR(validate); #endif /* CONFIG_SLUB_DEBUG */ #ifdef CONFIG_FAILSLAB static ssize_t failslab_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_FAILSLAB)); } static ssize_t failslab_store(struct kmem_cache *s, const char *buf, size_t length) { if (s->refcount > 1) return -EINVAL; if (buf[0] == '1') WRITE_ONCE(s->flags, s->flags | SLAB_FAILSLAB); else WRITE_ONCE(s->flags, s->flags & ~SLAB_FAILSLAB); return length; } SLAB_ATTR(failslab); #endif static ssize_t shrink_show(struct kmem_cache *s, char *buf) { return 0; } static ssize_t shrink_store(struct kmem_cache *s, const char *buf, size_t length) { if (buf[0] == '1') kmem_cache_shrink(s); else return -EINVAL; return length; } SLAB_ATTR(shrink); #ifdef CONFIG_NUMA static ssize_t remote_node_defrag_ratio_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%u\n", s->remote_node_defrag_ratio / 10); } static ssize_t remote_node_defrag_ratio_store(struct kmem_cache *s, const char *buf, size_t length) { unsigned int ratio; int err; err = kstrtouint(buf, 10, &ratio); if (err) return err; if (ratio > 100) return -ERANGE; s->remote_node_defrag_ratio = ratio * 10; return length; } SLAB_ATTR(remote_node_defrag_ratio); #endif #ifdef CONFIG_SLUB_STATS static int show_stat(struct kmem_cache *s, char *buf, enum stat_item si) { unsigned long sum = 0; int cpu; int len = 0; int *data = kmalloc_array(nr_cpu_ids, sizeof(int), GFP_KERNEL); if (!data) return -ENOMEM; for_each_online_cpu(cpu) { unsigned x = per_cpu_ptr(s->cpu_slab, cpu)->stat[si]; data[cpu] = x; sum += x; } len += sysfs_emit_at(buf, len, "%lu", sum); #ifdef CONFIG_SMP for_each_online_cpu(cpu) { if (data[cpu]) len += sysfs_emit_at(buf, len, " C%d=%u", cpu, data[cpu]); } #endif kfree(data); len += sysfs_emit_at(buf, len, "\n"); return len; } static void clear_stat(struct kmem_cache *s, enum stat_item si) { int cpu; for_each_online_cpu(cpu) per_cpu_ptr(s->cpu_slab, cpu)->stat[si] = 0; } #define STAT_ATTR(si, text) \ static ssize_t text##_show(struct kmem_cache *s, char *buf) \ { \ return show_stat(s, buf, si); \ } \ static ssize_t text##_store(struct kmem_cache *s, \ const char *buf, size_t length) \ { \ if (buf[0] != '0') \ return -EINVAL; \ clear_stat(s, si); \ return length; \ } \ SLAB_ATTR(text); \ STAT_ATTR(ALLOC_FASTPATH, alloc_fastpath); STAT_ATTR(ALLOC_SLOWPATH, alloc_slowpath); STAT_ATTR(FREE_FASTPATH, free_fastpath); STAT_ATTR(FREE_SLOWPATH, free_slowpath); STAT_ATTR(FREE_FROZEN, free_frozen); STAT_ATTR(FREE_ADD_PARTIAL, free_add_partial); STAT_ATTR(FREE_REMOVE_PARTIAL, free_remove_partial); STAT_ATTR(ALLOC_FROM_PARTIAL, alloc_from_partial); STAT_ATTR(ALLOC_SLAB, alloc_slab); STAT_ATTR(ALLOC_REFILL, alloc_refill); STAT_ATTR(ALLOC_NODE_MISMATCH, alloc_node_mismatch); STAT_ATTR(FREE_SLAB, free_slab); STAT_ATTR(CPUSLAB_FLUSH, cpuslab_flush); STAT_ATTR(DEACTIVATE_FULL, deactivate_full); STAT_ATTR(DEACTIVATE_EMPTY, deactivate_empty); STAT_ATTR(DEACTIVATE_TO_HEAD, deactivate_to_head); STAT_ATTR(DEACTIVATE_TO_TAIL, deactivate_to_tail); STAT_ATTR(DEACTIVATE_REMOTE_FREES, deactivate_remote_frees); STAT_ATTR(DEACTIVATE_BYPASS, deactivate_bypass); STAT_ATTR(ORDER_FALLBACK, order_fallback); STAT_ATTR(CMPXCHG_DOUBLE_CPU_FAIL, cmpxchg_double_cpu_fail); STAT_ATTR(CMPXCHG_DOUBLE_FAIL, cmpxchg_double_fail); STAT_ATTR(CPU_PARTIAL_ALLOC, cpu_partial_alloc); STAT_ATTR(CPU_PARTIAL_FREE, cpu_partial_free); STAT_ATTR(CPU_PARTIAL_NODE, cpu_partial_node); STAT_ATTR(CPU_PARTIAL_DRAIN, cpu_partial_drain); #endif /* CONFIG_SLUB_STATS */ #ifdef CONFIG_KFENCE static ssize_t skip_kfence_show(struct kmem_cache *s, char *buf) { return sysfs_emit(buf, "%d\n", !!(s->flags & SLAB_SKIP_KFENCE)); } static ssize_t skip_kfence_store(struct kmem_cache *s, const char *buf, size_t length) { int ret = length; if (buf[0] == '0') s->flags &= ~SLAB_SKIP_KFENCE; else if (buf[0] == '1') s->flags |= SLAB_SKIP_KFENCE; else ret = -EINVAL; return ret; } SLAB_ATTR(skip_kfence); #endif static struct attribute *slab_attrs[] = { &slab_size_attr.attr, &object_size_attr.attr, &objs_per_slab_attr.attr, &order_attr.attr, &min_partial_attr.attr, &cpu_partial_attr.attr, &objects_partial_attr.attr, &partial_attr.attr, &cpu_slabs_attr.attr, &ctor_attr.attr, &aliases_attr.attr, &align_attr.attr, &hwcache_align_attr.attr, &reclaim_account_attr.attr, &destroy_by_rcu_attr.attr, &shrink_attr.attr, &slabs_cpu_partial_attr.attr, #ifdef CONFIG_SLUB_DEBUG &total_objects_attr.attr, &objects_attr.attr, &slabs_attr.attr, &sanity_checks_attr.attr, &trace_attr.attr, &red_zone_attr.attr, &poison_attr.attr, &store_user_attr.attr, &validate_attr.attr, #endif #ifdef CONFIG_ZONE_DMA &cache_dma_attr.attr, #endif #ifdef CONFIG_NUMA &remote_node_defrag_ratio_attr.attr, #endif #ifdef CONFIG_SLUB_STATS &alloc_fastpath_attr.attr, &alloc_slowpath_attr.attr, &free_fastpath_attr.attr, &free_slowpath_attr.attr, &free_frozen_attr.attr, &free_add_partial_attr.attr, &free_remove_partial_attr.attr, &alloc_from_partial_attr.attr, &alloc_slab_attr.attr, &alloc_refill_attr.attr, &alloc_node_mismatch_attr.attr, &free_slab_attr.attr, &cpuslab_flush_attr.attr, &deactivate_full_attr.attr, &deactivate_empty_attr.attr, &deactivate_to_head_attr.attr, &deactivate_to_tail_attr.attr, &deactivate_remote_frees_attr.attr, &deactivate_bypass_attr.attr, &order_fallback_attr.attr, &cmpxchg_double_fail_attr.attr, &cmpxchg_double_cpu_fail_attr.attr, &cpu_partial_alloc_attr.attr, &cpu_partial_free_attr.attr, &cpu_partial_node_attr.attr, &cpu_partial_drain_attr.attr, #endif #ifdef CONFIG_FAILSLAB &failslab_attr.attr, #endif #ifdef CONFIG_HARDENED_USERCOPY &usersize_attr.attr, #endif #ifdef CONFIG_KFENCE &skip_kfence_attr.attr, #endif NULL }; static const struct attribute_group slab_attr_group = { .attrs = slab_attrs, }; static ssize_t slab_attr_show(struct kobject *kobj, struct attribute *attr, char *buf) { struct slab_attribute *attribute; struct kmem_cache *s; attribute = to_slab_attr(attr); s = to_slab(kobj); if (!attribute->show) return -EIO; return attribute->show(s, buf); } static ssize_t slab_attr_store(struct kobject *kobj, struct attribute *attr, const char *buf, size_t len) { struct slab_attribute *attribute; struct kmem_cache *s; attribute = to_slab_attr(attr); s = to_slab(kobj); if (!attribute->store) return -EIO; return attribute->store(s, buf, len); } static void kmem_cache_release(struct kobject *k) { slab_kmem_cache_release(to_slab(k)); } static const struct sysfs_ops slab_sysfs_ops = { .show = slab_attr_show, .store = slab_attr_store, }; static const struct kobj_type slab_ktype = { .sysfs_ops = &slab_sysfs_ops, .release = kmem_cache_release, }; static struct kset *slab_kset; static inline struct kset *cache_kset(struct kmem_cache *s) { return slab_kset; } #define ID_STR_LENGTH 32 /* Create a unique string id for a slab cache: * * Format :[flags-]size */ static char *create_unique_id(struct kmem_cache *s) { char *name = kmalloc(ID_STR_LENGTH, GFP_KERNEL); char *p = name; if (!name) return ERR_PTR(-ENOMEM); *p++ = ':'; /* * First flags affecting slabcache operations. We will only * get here for aliasable slabs so we do not need to support * too many flags. The flags here must cover all flags that * are matched during merging to guarantee that the id is * unique. */ if (s->flags & SLAB_CACHE_DMA) *p++ = 'd'; if (s->flags & SLAB_CACHE_DMA32) *p++ = 'D'; if (s->flags & SLAB_RECLAIM_ACCOUNT) *p++ = 'a'; if (s->flags & SLAB_CONSISTENCY_CHECKS) *p++ = 'F'; if (s->flags & SLAB_ACCOUNT) *p++ = 'A'; if (p != name + 1) *p++ = '-'; p += snprintf(p, ID_STR_LENGTH - (p - name), "%07u", s->size); if (WARN_ON(p > name + ID_STR_LENGTH - 1)) { kfree(name); return ERR_PTR(-EINVAL); } kmsan_unpoison_memory(name, p - name); return name; } static int sysfs_slab_add(struct kmem_cache *s) { int err; const char *name; struct kset *kset = cache_kset(s); int unmergeable = slab_unmergeable(s); if (!unmergeable && disable_higher_order_debug && (slub_debug & DEBUG_METADATA_FLAGS)) unmergeable = 1; if (unmergeable) { /* * Slabcache can never be merged so we can use the name proper. * This is typically the case for debug situations. In that * case we can catch duplicate names easily. */ sysfs_remove_link(&slab_kset->kobj, s->name); name = s->name; } else { /* * Create a unique name for the slab as a target * for the symlinks. */ name = create_unique_id(s); if (IS_ERR(name)) return PTR_ERR(name); } s->kobj.kset = kset; err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name); if (err) goto out; err = sysfs_create_group(&s->kobj, &slab_attr_group); if (err) goto out_del_kobj; if (!unmergeable) { /* Setup first alias */ sysfs_slab_alias(s, s->name); } out: if (!unmergeable) kfree(name); return err; out_del_kobj: kobject_del(&s->kobj); goto out; } void sysfs_slab_unlink(struct kmem_cache *s) { kobject_del(&s->kobj); } void sysfs_slab_release(struct kmem_cache *s) { kobject_put(&s->kobj); } /* * Need to buffer aliases during bootup until sysfs becomes * available lest we lose that information. */ struct saved_alias { struct kmem_cache *s; const char *name; struct saved_alias *next; }; static struct saved_alias *alias_list; static int sysfs_slab_alias(struct kmem_cache *s, const char *name) { struct saved_alias *al; if (slab_state == FULL) { /* * If we have a leftover link then remove it. */ sysfs_remove_link(&slab_kset->kobj, name); return sysfs_create_link(&slab_kset->kobj, &s->kobj, name); } al = kmalloc(sizeof(struct saved_alias), GFP_KERNEL); if (!al) return -ENOMEM; al->s = s; al->name = name; al->next = alias_list; alias_list = al; kmsan_unpoison_memory(al, sizeof(*al)); return 0; } static int __init slab_sysfs_init(void) { struct kmem_cache *s; int err; mutex_lock(&slab_mutex); slab_kset = kset_create_and_add("slab", NULL, kernel_kobj); if (!slab_kset) { mutex_unlock(&slab_mutex); pr_err("Cannot register slab subsystem.\n"); return -ENOMEM; } slab_state = FULL; list_for_each_entry(s, &slab_caches, list) { err = sysfs_slab_add(s); if (err) pr_err("SLUB: Unable to add boot slab %s to sysfs\n", s->name); } while (alias_list) { struct saved_alias *al = alias_list; alias_list = alias_list->next; err = sysfs_slab_alias(al->s, al->name); if (err) pr_err("SLUB: Unable to add boot slab alias %s to sysfs\n", al->name); kfree(al); } mutex_unlock(&slab_mutex); return 0; } late_initcall(slab_sysfs_init); #endif /* SLAB_SUPPORTS_SYSFS */ #if defined(CONFIG_SLUB_DEBUG) && defined(CONFIG_DEBUG_FS) static int slab_debugfs_show(struct seq_file *seq, void *v) { struct loc_track *t = seq->private; struct location *l; unsigned long idx; idx = (unsigned long) t->idx; if (idx < t->count) { l = &t->loc[idx]; seq_printf(seq, "%7ld ", l->count); if (l->addr) seq_printf(seq, "%pS", (void *)l->addr); else seq_puts(seq, ""); if (l->waste) seq_printf(seq, " waste=%lu/%lu", l->count * l->waste, l->waste); if (l->sum_time != l->min_time) { seq_printf(seq, " age=%ld/%llu/%ld", l->min_time, div_u64(l->sum_time, l->count), l->max_time); } else seq_printf(seq, " age=%ld", l->min_time); if (l->min_pid != l->max_pid) seq_printf(seq, " pid=%ld-%ld", l->min_pid, l->max_pid); else seq_printf(seq, " pid=%ld", l->min_pid); if (num_online_cpus() > 1 && !cpumask_empty(to_cpumask(l->cpus))) seq_printf(seq, " cpus=%*pbl", cpumask_pr_args(to_cpumask(l->cpus))); if (nr_online_nodes > 1 && !nodes_empty(l->nodes)) seq_printf(seq, " nodes=%*pbl", nodemask_pr_args(&l->nodes)); #ifdef CONFIG_STACKDEPOT { depot_stack_handle_t handle; unsigned long *entries; unsigned int nr_entries, j; handle = READ_ONCE(l->handle); if (handle) { nr_entries = stack_depot_fetch(handle, &entries); seq_puts(seq, "\n"); for (j = 0; j < nr_entries; j++) seq_printf(seq, " %pS\n", (void *)entries[j]); } } #endif seq_puts(seq, "\n"); } if (!idx && !t->count) seq_puts(seq, "No data\n"); return 0; } static void slab_debugfs_stop(struct seq_file *seq, void *v) { } static void *slab_debugfs_next(struct seq_file *seq, void *v, loff_t *ppos) { struct loc_track *t = seq->private; t->idx = ++(*ppos); if (*ppos <= t->count) return ppos; return NULL; } static int cmp_loc_by_count(const void *a, const void *b, const void *data) { struct location *loc1 = (struct location *)a; struct location *loc2 = (struct location *)b; if (loc1->count > loc2->count) return -1; else return 1; } static void *slab_debugfs_start(struct seq_file *seq, loff_t *ppos) { struct loc_track *t = seq->private; t->idx = *ppos; return ppos; } static const struct seq_operations slab_debugfs_sops = { .start = slab_debugfs_start, .next = slab_debugfs_next, .stop = slab_debugfs_stop, .show = slab_debugfs_show, }; static int slab_debug_trace_open(struct inode *inode, struct file *filep) { struct kmem_cache_node *n; enum track_item alloc; int node; struct loc_track *t = __seq_open_private(filep, &slab_debugfs_sops, sizeof(struct loc_track)); struct kmem_cache *s = file_inode(filep)->i_private; unsigned long *obj_map; if (!t) return -ENOMEM; obj_map = bitmap_alloc(oo_objects(s->oo), GFP_KERNEL); if (!obj_map) { seq_release_private(inode, filep); return -ENOMEM; } if (strcmp(filep->f_path.dentry->d_name.name, "alloc_traces") == 0) alloc = TRACK_ALLOC; else alloc = TRACK_FREE; if (!alloc_loc_track(t, PAGE_SIZE / sizeof(struct location), GFP_KERNEL)) { bitmap_free(obj_map); seq_release_private(inode, filep); return -ENOMEM; } for_each_kmem_cache_node(s, node, n) { unsigned long flags; struct slab *slab; if (!node_nr_slabs(n)) continue; spin_lock_irqsave(&n->list_lock, flags); list_for_each_entry(slab, &n->partial, slab_list) process_slab(t, s, slab, alloc, obj_map); list_for_each_entry(slab, &n->full, slab_list) process_slab(t, s, slab, alloc, obj_map); spin_unlock_irqrestore(&n->list_lock, flags); } /* Sort locations by count */ sort_r(t->loc, t->count, sizeof(struct location), cmp_loc_by_count, NULL, NULL); bitmap_free(obj_map); return 0; } static int slab_debug_trace_release(struct inode *inode, struct file *file) { struct seq_file *seq = file->private_data; struct loc_track *t = seq->private; free_loc_track(t); return seq_release_private(inode, file); } static const struct file_operations slab_debugfs_fops = { .open = slab_debug_trace_open, .read = seq_read, .llseek = seq_lseek, .release = slab_debug_trace_release, }; static void debugfs_slab_add(struct kmem_cache *s) { struct dentry *slab_cache_dir; if (unlikely(!slab_debugfs_root)) return; slab_cache_dir = debugfs_create_dir(s->name, slab_debugfs_root); debugfs_create_file("alloc_traces", 0400, slab_cache_dir, s, &slab_debugfs_fops); debugfs_create_file("free_traces", 0400, slab_cache_dir, s, &slab_debugfs_fops); } void debugfs_slab_release(struct kmem_cache *s) { debugfs_lookup_and_remove(s->name, slab_debugfs_root); } static int __init slab_debugfs_init(void) { struct kmem_cache *s; slab_debugfs_root = debugfs_create_dir("slab", NULL); list_for_each_entry(s, &slab_caches, list) if (s->flags & SLAB_STORE_USER) debugfs_slab_add(s); return 0; } __initcall(slab_debugfs_init); #endif /* * The /proc/slabinfo ABI */ #ifdef CONFIG_SLUB_DEBUG void get_slabinfo(struct kmem_cache *s, struct slabinfo *sinfo) { unsigned long nr_slabs = 0; unsigned long nr_objs = 0; unsigned long nr_free = 0; int node; struct kmem_cache_node *n; for_each_kmem_cache_node(s, node, n) { nr_slabs += node_nr_slabs(n); nr_objs += node_nr_objs(n); nr_free += count_partial(n, count_free); } sinfo->active_objs = nr_objs - nr_free; sinfo->num_objs = nr_objs; sinfo->active_slabs = nr_slabs; sinfo->num_slabs = nr_slabs; sinfo->objects_per_slab = oo_objects(s->oo); sinfo->cache_order = oo_order(s->oo); } void slabinfo_show_stats(struct seq_file *m, struct kmem_cache *s) { } ssize_t slabinfo_write(struct file *file, const char __user *buffer, size_t count, loff_t *ppos) { return -EIO; } #endif /* CONFIG_SLUB_DEBUG */