/* * 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 operatios * 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 /* struct reclaim_state */ #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 "internal.h" /* * Lock order: * 1. slab_mutex (Global Mutex) * 2. node->list_lock * 3. slab_lock(page) (Only on some arches and 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. * * The slab_lock is only used for debugging and on arches that do not * have the ability to do a cmpxchg_double. It only protects the second * double word in the page struct. Meaning * A. page->freelist -> List of object free in a page * B. page->counters -> Counters of objects * C. page->frozen -> frozen state * * If a slab is frozen then it is exempt from list management. It is not * on any list. The processor that froze the slab is the one who can * perform list operations on the page. 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 page's freelist. * * 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. * Interrupts are disabled during allocation and deallocation in order to * make the slab allocator safe to use in the context of an irq. In addition * interrupts are disabled to ensure that the processor does not change * while handling per_cpu slabs, due to kernel preemption. * * 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. * * Overloading of page flags that are otherwise used for LRU management. * * PageActive 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. * * PageError Slab requires special handling due to debug * options set. This moves slab handling out of * the fast path and disables lockless freelists. */ static inline int kmem_cache_debug(struct kmem_cache *s) { #ifdef CONFIG_SLUB_DEBUG return unlikely(s->flags & SLAB_DEBUG_FLAGS); #else return 0; #endif } void *fixup_red_left(struct kmem_cache *s, void *p) { if (kmem_cache_debug(s) && s->flags & 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 test recovery from slab corruption on boot */ #undef SLUB_RESILIENCY_TEST /* Enable to log cmpxchg failures */ #undef SLUB_DEBUG_CMPXCHG /* * Mininum 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 #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 slub_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 page.objects is u15 */ /* Internal SLUB flags */ #define __OBJECT_POISON 0x80000000UL /* Poison object */ #define __CMPXCHG_DOUBLE 0x40000000UL /* Use cmpxchg_double */ /* * Tracking user of a slab. */ #define TRACK_ADDRS_COUNT 16 struct track { unsigned long addr; /* Called from address */ #ifdef CONFIG_STACKTRACE unsigned long addrs[TRACK_ADDRS_COUNT]; /* Called from address */ #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 CONFIG_SYSFS static int sysfs_slab_add(struct kmem_cache *); static int sysfs_slab_alias(struct kmem_cache *, const char *); static void memcg_propagate_slab_attrs(struct kmem_cache *s); #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; } static inline void memcg_propagate_slab_attrs(struct kmem_cache *s) { } #endif 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 } /******************************************************************** * Core slab cache functions *******************************************************************/ static inline void *get_freepointer(struct kmem_cache *s, void *object) { return *(void **)(object + s->offset); } static void prefetch_freepointer(const struct kmem_cache *s, void *object) { prefetch(object + s->offset); } static inline void *get_freepointer_safe(struct kmem_cache *s, void *object) { void *p; if (!debug_pagealloc_enabled()) return get_freepointer(s, object); probe_kernel_read(&p, (void **)(object + s->offset), sizeof(p)); return p; } static inline void set_freepointer(struct kmem_cache *s, void *object, void *fp) { *(void **)(object + s->offset) = fp; } /* 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) #define for_each_object_idx(__p, __idx, __s, __addr, __objects) \ for (__p = fixup_red_left(__s, __addr), __idx = 1; \ __idx <= __objects; \ __p += (__s)->size, __idx++) /* Determine object index from a given position */ static inline int slab_index(void *p, struct kmem_cache *s, void *addr) { return (p - addr) / s->size; } static inline int order_objects(int order, unsigned long size, int reserved) { return ((PAGE_SIZE << order) - reserved) / size; } static inline struct kmem_cache_order_objects oo_make(int order, unsigned long size, int reserved) { struct kmem_cache_order_objects x = { (order << OO_SHIFT) + order_objects(order, size, reserved) }; return x; } static inline int oo_order(struct kmem_cache_order_objects x) { return x.x >> OO_SHIFT; } static inline int oo_objects(struct kmem_cache_order_objects x) { return x.x & OO_MASK; } /* * Per slab locking using the pagelock */ static __always_inline void slab_lock(struct page *page) { VM_BUG_ON_PAGE(PageTail(page), page); bit_spin_lock(PG_locked, &page->flags); } static __always_inline void slab_unlock(struct page *page) { VM_BUG_ON_PAGE(PageTail(page), page); __bit_spin_unlock(PG_locked, &page->flags); } static inline void set_page_slub_counters(struct page *page, unsigned long counters_new) { struct page tmp; tmp.counters = counters_new; /* * page->counters can cover frozen/inuse/objects as well * as page->_refcount. If we assign to ->counters directly * we run the risk of losing updates to page->_refcount, so * be careful and only assign to the fields we need. */ page->frozen = tmp.frozen; page->inuse = tmp.inuse; page->objects = tmp.objects; } /* Interrupts must be disabled (for the fallback code to work right) */ static inline bool __cmpxchg_double_slab(struct kmem_cache *s, struct page *page, void *freelist_old, unsigned long counters_old, void *freelist_new, unsigned long counters_new, const char *n) { VM_BUG_ON(!irqs_disabled()); #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \ defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE) if (s->flags & __CMPXCHG_DOUBLE) { if (cmpxchg_double(&page->freelist, &page->counters, freelist_old, counters_old, freelist_new, counters_new)) return true; } else #endif { slab_lock(page); if (page->freelist == freelist_old && page->counters == counters_old) { page->freelist = freelist_new; set_page_slub_counters(page, counters_new); slab_unlock(page); return true; } slab_unlock(page); } 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 cmpxchg_double_slab(struct kmem_cache *s, struct page *page, void *freelist_old, unsigned long counters_old, void *freelist_new, unsigned long counters_new, const char *n) { #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \ defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE) if (s->flags & __CMPXCHG_DOUBLE) { if (cmpxchg_double(&page->freelist, &page->counters, freelist_old, counters_old, freelist_new, counters_new)) return true; } else #endif { unsigned long flags; local_irq_save(flags); slab_lock(page); if (page->freelist == freelist_old && page->counters == counters_old) { page->freelist = freelist_new; set_page_slub_counters(page, counters_new); slab_unlock(page); local_irq_restore(flags); return true; } slab_unlock(page); local_irq_restore(flags); } 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 /* * Determine a map of object in use on a page. * * Node listlock must be held to guarantee that the page does * not vanish from under us. */ static void get_map(struct kmem_cache *s, struct page *page, unsigned long *map) { void *p; void *addr = page_address(page); for (p = page->freelist; p; p = get_freepointer(s, p)) set_bit(slab_index(p, s, addr), map); } static inline 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 int slub_debug = DEBUG_DEFAULT_FLAGS; #else static int slub_debug; #endif static char *slub_debug_slabs; 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 page *page, void *object) { void *base; if (!object) return 1; base = page_address(page); object = restore_red_left(s, object); if (object < base || object >= base + page->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, addr, length, 1); metadata_access_disable(); } static struct track *get_track(struct kmem_cache *s, void *object, enum track_item alloc) { struct track *p; if (s->offset) p = object + s->offset + sizeof(void *); else p = object + s->inuse; return p + alloc; } static void set_track(struct kmem_cache *s, void *object, enum track_item alloc, unsigned long addr) { struct track *p = get_track(s, object, alloc); if (addr) { #ifdef CONFIG_STACKTRACE struct stack_trace trace; int i; trace.nr_entries = 0; trace.max_entries = TRACK_ADDRS_COUNT; trace.entries = p->addrs; trace.skip = 3; metadata_access_enable(); save_stack_trace(&trace); metadata_access_disable(); /* See rant in lockdep.c */ if (trace.nr_entries != 0 && trace.entries[trace.nr_entries - 1] == ULONG_MAX) trace.nr_entries--; for (i = trace.nr_entries; i < TRACK_ADDRS_COUNT; i++) p->addrs[i] = 0; #endif p->addr = addr; p->cpu = smp_processor_id(); p->pid = current->pid; p->when = jiffies; } else memset(p, 0, sizeof(struct track)); } static void init_tracking(struct kmem_cache *s, void *object) { if (!(s->flags & SLAB_STORE_USER)) return; set_track(s, object, TRACK_FREE, 0UL); set_track(s, object, TRACK_ALLOC, 0UL); } static void print_track(const char *s, struct track *t) { if (!t->addr) return; pr_err("INFO: %s in %pS age=%lu cpu=%u pid=%d\n", s, (void *)t->addr, jiffies - t->when, t->cpu, t->pid); #ifdef CONFIG_STACKTRACE { int i; for (i = 0; i < TRACK_ADDRS_COUNT; i++) if (t->addrs[i]) pr_err("\t%pS\n", (void *)t->addrs[i]); else break; } #endif } static void print_tracking(struct kmem_cache *s, void *object) { if (!(s->flags & SLAB_STORE_USER)) return; print_track("Allocated", get_track(s, object, TRACK_ALLOC)); print_track("Freed", get_track(s, object, TRACK_FREE)); } static void print_page_info(struct page *page) { pr_err("INFO: Slab 0x%p objects=%u used=%u fp=0x%p flags=0x%04lx\n", page, page->objects, page->inuse, page->freelist, page->flags); } 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"); add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE); va_end(args); } static void slab_fix(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("FIX %s: %pV\n", s->name, &vaf); va_end(args); } static bool freelist_corrupted(struct kmem_cache *s, struct page *page, void **freelist, void *nextfree) { if ((s->flags & SLAB_CONSISTENCY_CHECKS) && !check_valid_pointer(s, page, nextfree) && freelist) { object_err(s, page, *freelist, "Freechain corrupt"); *freelist = NULL; slab_fix(s, "Isolate corrupted freechain"); return true; } return false; } static void print_trailer(struct kmem_cache *s, struct page *page, u8 *p) { unsigned int off; /* Offset of last byte */ u8 *addr = page_address(page); print_tracking(s, p); print_page_info(page); pr_err("INFO: 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 long, 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); if (s->offset) off = s->offset + sizeof(void *); else off = s->inuse; if (s->flags & SLAB_STORE_USER) off += 2 * sizeof(struct track); off += kasan_metadata_size(s); 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(); } void object_err(struct kmem_cache *s, struct page *page, u8 *object, char *reason) { slab_bug(s, "%s", reason); print_trailer(s, page, object); } static __printf(3, 4) void slab_err(struct kmem_cache *s, struct page *page, const char *fmt, ...) { va_list args; char buf[100]; va_start(args, fmt); vsnprintf(buf, sizeof(buf), fmt, args); va_end(args); slab_bug(s, "%s", buf); print_page_info(page); dump_stack(); } static void init_object(struct kmem_cache *s, void *object, u8 val) { u8 *p = object; if (s->flags & SLAB_RED_ZONE) memset(p - s->red_left_pad, val, s->red_left_pad); if (s->flags & __OBJECT_POISON) { memset(p, POISON_FREE, s->object_size - 1); p[s->object_size - 1] = POISON_END; } if (s->flags & SLAB_RED_ZONE) memset(p + s->object_size, val, s->inuse - s->object_size); } static void restore_bytes(struct kmem_cache *s, char *message, u8 data, void *from, void *to) { slab_fix(s, "Restoring 0x%p-0x%p=0x%x\n", from, to - 1, data); memset(from, data, to - from); } static int check_bytes_and_report(struct kmem_cache *s, struct page *page, u8 *object, char *what, u8 *start, unsigned int value, unsigned int bytes) { u8 *fault; u8 *end; metadata_access_enable(); fault = memchr_inv(start, value, bytes); metadata_access_disable(); if (!fault) return 1; end = start + bytes; while (end > fault && end[-1] == value) end--; slab_bug(s, "%s overwritten", what); pr_err("INFO: 0x%p-0x%p. First byte 0x%x instead of 0x%x\n", fault, end - 1, fault[0], value); print_trailer(s, page, object); 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 the first word 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. Padding to reach required alignment boundary or at mininum * 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 page *page, u8 *p) { unsigned long off = s->inuse; /* The end of info */ if (s->offset) /* Freepointer is placed after the object. */ off += sizeof(void *); if (s->flags & SLAB_STORE_USER) /* We also have user information there */ off += 2 * sizeof(struct track); off += kasan_metadata_size(s); if (size_from_object(s) == off) return 1; return check_bytes_and_report(s, page, p, "Object padding", p + off, POISON_INUSE, size_from_object(s) - off); } /* Check the pad bytes at the end of a slab page */ static int slab_pad_check(struct kmem_cache *s, struct page *page) { u8 *start; u8 *fault; u8 *end; int length; int remainder; if (!(s->flags & SLAB_POISON)) return 1; start = page_address(page); length = (PAGE_SIZE << compound_order(page)) - s->reserved; end = start + length; remainder = length % s->size; if (!remainder) return 1; metadata_access_enable(); fault = memchr_inv(end - remainder, POISON_INUSE, remainder); metadata_access_disable(); if (!fault) return 1; while (end > fault && end[-1] == POISON_INUSE) end--; slab_err(s, page, "Padding overwritten. 0x%p-0x%p", fault, end - 1); print_section(KERN_ERR, "Padding ", end - remainder, remainder); restore_bytes(s, "slab padding", POISON_INUSE, end - remainder, end); return 0; } static int check_object(struct kmem_cache *s, struct page *page, void *object, u8 val) { u8 *p = object; u8 *endobject = object + s->object_size; if (s->flags & SLAB_RED_ZONE) { if (!check_bytes_and_report(s, page, object, "Redzone", object - s->red_left_pad, val, s->red_left_pad)) return 0; if (!check_bytes_and_report(s, page, object, "Redzone", endobject, val, s->inuse - s->object_size)) return 0; } else { if ((s->flags & SLAB_POISON) && s->object_size < s->inuse) { check_bytes_and_report(s, page, 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) && (!check_bytes_and_report(s, page, p, "Poison", p, POISON_FREE, s->object_size - 1) || !check_bytes_and_report(s, page, p, "Poison", p + s->object_size - 1, POISON_END, 1))) return 0; /* * check_pad_bytes cleans up on its own. */ check_pad_bytes(s, page, p); } if (!s->offset && 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, page, get_freepointer(s, p))) { object_err(s, page, 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 page *page) { int maxobj; VM_BUG_ON(!irqs_disabled()); if (!PageSlab(page)) { slab_err(s, page, "Not a valid slab page"); return 0; } maxobj = order_objects(compound_order(page), s->size, s->reserved); if (page->objects > maxobj) { slab_err(s, page, "objects %u > max %u", page->objects, maxobj); return 0; } if (page->inuse > page->objects) { slab_err(s, page, "inuse %u > max %u", page->inuse, page->objects); return 0; } /* Slab_pad_check fixes things up after itself */ slab_pad_check(s, page); return 1; } /* * Determine if a certain object on a page 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 page *page, void *search) { int nr = 0; void *fp; void *object = NULL; int max_objects; fp = page->freelist; while (fp && nr <= page->objects) { if (fp == search) return 1; if (!check_valid_pointer(s, page, fp)) { if (object) { object_err(s, page, object, "Freechain corrupt"); set_freepointer(s, object, NULL); } else { slab_err(s, page, "Freepointer corrupt"); page->freelist = NULL; page->inuse = page->objects; slab_fix(s, "Freelist cleared"); return 0; } break; } object = fp; fp = get_freepointer(s, object); nr++; } max_objects = order_objects(compound_order(page), s->size, s->reserved); if (max_objects > MAX_OBJS_PER_PAGE) max_objects = MAX_OBJS_PER_PAGE; if (page->objects != max_objects) { slab_err(s, page, "Wrong number of objects. Found %d but should be %d", page->objects, max_objects); page->objects = max_objects; slab_fix(s, "Number of objects adjusted."); } if (page->inuse != page->objects - nr) { slab_err(s, page, "Wrong object count. Counter is %d but counted were %d", page->inuse, page->objects - nr); page->inuse = page->objects - nr; slab_fix(s, "Object count adjusted."); } return search == NULL; } static void trace(struct kmem_cache *s, struct page *page, 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, page->inuse, page->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 page *page) { if (!(s->flags & SLAB_STORE_USER)) return; lockdep_assert_held(&n->list_lock); list_add(&page->lru, &n->full); } static void remove_full(struct kmem_cache *s, struct kmem_cache_node *n, struct page *page) { if (!(s->flags & SLAB_STORE_USER)) return; lockdep_assert_held(&n->list_lock); list_del(&page->lru); } /* Tracking of the number of slabs for debugging purposes */ static inline unsigned long slabs_node(struct kmem_cache *s, int node) { struct kmem_cache_node *n = get_node(s, node); return atomic_long_read(&n->nr_slabs); } 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); /* * May be called early in order to allocate a slab for the * kmem_cache_node structure. Solve the chicken-egg * dilemma by deferring the increment of the count during * bootstrap (see early_kmem_cache_node_alloc). */ if (likely(n)) { 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, struct page *page, void *object) { if (!(s->flags & (SLAB_STORE_USER|SLAB_RED_ZONE|__OBJECT_POISON))) return; init_object(s, object, SLUB_RED_INACTIVE); init_tracking(s, object); } static inline int alloc_consistency_checks(struct kmem_cache *s, struct page *page, void *object, unsigned long addr) { if (!check_slab(s, page)) return 0; if (!check_valid_pointer(s, page, object)) { object_err(s, page, object, "Freelist Pointer check fails"); return 0; } if (!check_object(s, page, object, SLUB_RED_INACTIVE)) return 0; return 1; } static noinline int alloc_debug_processing(struct kmem_cache *s, struct page *page, void *object, unsigned long addr) { if (s->flags & SLAB_CONSISTENCY_CHECKS) { if (!alloc_consistency_checks(s, page, object, addr)) goto bad; } /* Success perform special debug activities for allocs */ if (s->flags & SLAB_STORE_USER) set_track(s, object, TRACK_ALLOC, addr); trace(s, page, object, 1); init_object(s, object, SLUB_RED_ACTIVE); return 1; bad: if (PageSlab(page)) { /* * 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"); page->inuse = page->objects; page->freelist = NULL; } return 0; } static inline int free_consistency_checks(struct kmem_cache *s, struct page *page, void *object, unsigned long addr) { if (!check_valid_pointer(s, page, object)) { slab_err(s, page, "Invalid object pointer 0x%p", object); return 0; } if (on_freelist(s, page, object)) { object_err(s, page, object, "Object already free"); return 0; } if (!check_object(s, page, object, SLUB_RED_ACTIVE)) return 0; if (unlikely(s != page->slab_cache)) { if (!PageSlab(page)) { slab_err(s, page, "Attempt to free object(0x%p) outside of slab", object); } else if (!page->slab_cache) { pr_err("SLUB : no slab for object 0x%p.\n", object); dump_stack(); } else object_err(s, page, object, "page slab pointer corrupt."); return 0; } return 1; } /* Supports checking bulk free of a constructed freelist */ static noinline int free_debug_processing( struct kmem_cache *s, struct page *page, void *head, void *tail, int bulk_cnt, unsigned long addr) { struct kmem_cache_node *n = get_node(s, page_to_nid(page)); void *object = head; int cnt = 0; unsigned long uninitialized_var(flags); int ret = 0; spin_lock_irqsave(&n->list_lock, flags); slab_lock(page); if (s->flags & SLAB_CONSISTENCY_CHECKS) { if (!check_slab(s, page)) goto out; } next_object: cnt++; if (s->flags & SLAB_CONSISTENCY_CHECKS) { if (!free_consistency_checks(s, page, object, addr)) goto out; } if (s->flags & SLAB_STORE_USER) set_track(s, object, TRACK_FREE, addr); trace(s, page, 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; } ret = 1; out: if (cnt != bulk_cnt) slab_err(s, page, "Bulk freelist count(%d) invalid(%d)\n", bulk_cnt, cnt); slab_unlock(page); spin_unlock_irqrestore(&n->list_lock, flags); if (!ret) slab_fix(s, "Object at 0x%p not freed", object); return ret; } static int __init setup_slub_debug(char *str) { slub_debug = DEBUG_DEFAULT_FLAGS; if (*str++ != '=' || !*str) /* * No options specified. Switch on full debugging. */ goto out; if (*str == ',') /* * No options but restriction on slabs. This means full * debugging for slabs matching a pattern. */ goto check_slabs; slub_debug = 0; if (*str == '-') /* * Switch off all debugging measures. */ goto out; /* * Determine which debug features should be switched on */ for (; *str && *str != ','; str++) { switch (tolower(*str)) { case 'f': slub_debug |= SLAB_CONSISTENCY_CHECKS; break; case 'z': slub_debug |= SLAB_RED_ZONE; break; case 'p': slub_debug |= SLAB_POISON; break; case 'u': slub_debug |= SLAB_STORE_USER; break; case 't': slub_debug |= SLAB_TRACE; break; case 'a': slub_debug |= SLAB_FAILSLAB; break; case 'o': /* * Avoid enabling debugging on caches if its minimum * order would increase as a result. */ disable_higher_order_debug = 1; break; default: pr_err("slub_debug option '%c' unknown. skipped\n", *str); } } check_slabs: if (*str == ',') slub_debug_slabs = str + 1; out: return 1; } __setup("slub_debug", setup_slub_debug); unsigned long kmem_cache_flags(unsigned long object_size, unsigned long flags, const char *name, void (*ctor)(void *)) { /* * Enable debugging if selected on the kernel commandline. */ if (slub_debug && (!slub_debug_slabs || (name && !strncmp(slub_debug_slabs, name, strlen(slub_debug_slabs))))) flags |= slub_debug; return flags; } #else /* !CONFIG_SLUB_DEBUG */ static inline void setup_object_debug(struct kmem_cache *s, struct page *page, void *object) {} static inline int alloc_debug_processing(struct kmem_cache *s, struct page *page, void *object, unsigned long addr) { return 0; } static inline int free_debug_processing( struct kmem_cache *s, struct page *page, void *head, void *tail, int bulk_cnt, unsigned long addr) { return 0; } static inline int slab_pad_check(struct kmem_cache *s, struct page *page) { return 1; } static inline int check_object(struct kmem_cache *s, struct page *page, void *object, u8 val) { return 1; } static inline void add_full(struct kmem_cache *s, struct kmem_cache_node *n, struct page *page) {} static inline void remove_full(struct kmem_cache *s, struct kmem_cache_node *n, struct page *page) {} unsigned long kmem_cache_flags(unsigned long object_size, unsigned long flags, const char *name, void (*ctor)(void *)) { return flags; } #define slub_debug 0 #define disable_higher_order_debug 0 static inline unsigned long slabs_node(struct kmem_cache *s, int node) { return 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) {} static bool freelist_corrupted(struct kmem_cache *s, struct page *page, void **freelist, void *nextfree) { return false; } #endif /* CONFIG_SLUB_DEBUG */ /* * Hooks for other subsystems that check memory allocations. In a typical * production configuration these hooks all should produce no code at all. */ static inline void kmalloc_large_node_hook(void *ptr, size_t size, gfp_t flags) { kmemleak_alloc(ptr, size, 1, flags); kasan_kmalloc_large(ptr, size, flags); } static inline void kfree_hook(const void *x) { kmemleak_free(x); kasan_kfree_large(x); } static inline void *slab_free_hook(struct kmem_cache *s, void *x) { void *freeptr; kmemleak_free_recursive(x, s->flags); /* * Trouble is that we may no longer disable interrupts in the fast path * So in order to make the debug calls that expect irqs to be * disabled we need to disable interrupts temporarily. */ #if defined(CONFIG_KMEMCHECK) || defined(CONFIG_LOCKDEP) { unsigned long flags; local_irq_save(flags); kmemcheck_slab_free(s, x, s->object_size); debug_check_no_locks_freed(x, s->object_size); local_irq_restore(flags); } #endif if (!(s->flags & SLAB_DEBUG_OBJECTS)) debug_check_no_obj_freed(x, s->object_size); freeptr = get_freepointer(s, x); /* * kasan_slab_free() may put x into memory quarantine, delaying its * reuse. In this case the object's freelist pointer is changed. */ kasan_slab_free(s, x); return freeptr; } static inline void slab_free_freelist_hook(struct kmem_cache *s, void *head, void *tail) { /* * Compiler cannot detect this function can be removed if slab_free_hook() * evaluates to nothing. Thus, catch all relevant config debug options here. */ #if defined(CONFIG_KMEMCHECK) || \ defined(CONFIG_LOCKDEP) || \ defined(CONFIG_DEBUG_KMEMLEAK) || \ defined(CONFIG_DEBUG_OBJECTS_FREE) || \ defined(CONFIG_KASAN) void *object = head; void *tail_obj = tail ? : head; void *freeptr; do { freeptr = slab_free_hook(s, object); } while ((object != tail_obj) && (object = freeptr)); #endif } static void setup_object(struct kmem_cache *s, struct page *page, void *object) { setup_object_debug(s, page, object); kasan_init_slab_obj(s, object); if (unlikely(s->ctor)) { kasan_unpoison_object_data(s, object); s->ctor(object); kasan_poison_object_data(s, object); } } /* * Slab allocation and freeing */ static inline struct page *alloc_slab_page(struct kmem_cache *s, gfp_t flags, int node, struct kmem_cache_order_objects oo) { struct page *page; int order = oo_order(oo); flags |= __GFP_NOTRACK; if (node == NUMA_NO_NODE) page = alloc_pages(flags, order); else page = __alloc_pages_node(node, flags, order); if (page && memcg_charge_slab(page, flags, order, s)) { __free_pages(page, order); page = NULL; } return page; } #ifdef CONFIG_SLAB_FREELIST_RANDOM /* Pre-initialize the random sequence cache */ static int init_cache_random_seq(struct kmem_cache *s) { int err; unsigned long i, count = oo_objects(s->oo); /* 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) { 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, struct page *page, 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 page *page) { void *start; void *cur; void *next; unsigned long idx, pos, page_limit, freelist_count; if (page->objects < 2 || !s->random_seq) return false; freelist_count = oo_objects(s->oo); pos = get_random_int() % freelist_count; page_limit = page->objects * s->size; start = fixup_red_left(s, page_address(page)); /* First entry is used as the base of the freelist */ cur = next_freelist_entry(s, page, &pos, start, page_limit, freelist_count); page->freelist = cur; for (idx = 1; idx < page->objects; idx++) { setup_object(s, page, cur); next = next_freelist_entry(s, page, &pos, start, page_limit, freelist_count); set_freepointer(s, cur, next); cur = next; } setup_object(s, page, cur); 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 page *page) { return false; } #endif /* CONFIG_SLAB_FREELIST_RANDOM */ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node) { struct page *page; struct kmem_cache_order_objects oo = s->oo; gfp_t alloc_gfp; void *start, *p; int idx, order; bool shuffle; flags &= gfp_allowed_mask; if (gfpflags_allow_blocking(flags)) local_irq_enable(); 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|__GFP_NOFAIL); page = alloc_slab_page(s, alloc_gfp, node, oo); if (unlikely(!page)) { oo = s->min; alloc_gfp = flags; /* * Allocation may have failed due to fragmentation. * Try a lower order alloc if possible */ page = alloc_slab_page(s, alloc_gfp, node, oo); if (unlikely(!page)) goto out; stat(s, ORDER_FALLBACK); } if (kmemcheck_enabled && !(s->flags & (SLAB_NOTRACK | DEBUG_DEFAULT_FLAGS))) { int pages = 1 << oo_order(oo); kmemcheck_alloc_shadow(page, oo_order(oo), alloc_gfp, node); /* * Objects from caches that have a constructor don't get * cleared when they're allocated, so we need to do it here. */ if (s->ctor) kmemcheck_mark_uninitialized_pages(page, pages); else kmemcheck_mark_unallocated_pages(page, pages); } page->objects = oo_objects(oo); order = compound_order(page); page->slab_cache = s; __SetPageSlab(page); if (page_is_pfmemalloc(page)) SetPageSlabPfmemalloc(page); start = page_address(page); if (unlikely(s->flags & SLAB_POISON)) memset(start, POISON_INUSE, PAGE_SIZE << order); kasan_poison_slab(page); shuffle = shuffle_freelist(s, page); if (!shuffle) { for_each_object_idx(p, idx, s, start, page->objects) { setup_object(s, page, p); if (likely(idx < page->objects)) set_freepointer(s, p, p + s->size); else set_freepointer(s, p, NULL); } page->freelist = fixup_red_left(s, start); } page->inuse = page->objects; page->frozen = 1; out: if (gfpflags_allow_blocking(flags)) local_irq_disable(); if (!page) return NULL; mod_zone_page_state(page_zone(page), (s->flags & SLAB_RECLAIM_ACCOUNT) ? NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE, 1 << oo_order(oo)); inc_slabs_node(s, page_to_nid(page), page->objects); return page; } static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node) { if (unlikely(flags & GFP_SLAB_BUG_MASK)) { gfp_t invalid_mask = flags & GFP_SLAB_BUG_MASK; flags &= ~GFP_SLAB_BUG_MASK; pr_warn("Unexpected gfp: %#x (%pGg). Fixing up to gfp: %#x (%pGg). Fix your code!\n", invalid_mask, &invalid_mask, flags, &flags); } return allocate_slab(s, flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node); } static void __free_slab(struct kmem_cache *s, struct page *page) { int order = compound_order(page); int pages = 1 << order; if (s->flags & SLAB_CONSISTENCY_CHECKS) { void *p; slab_pad_check(s, page); for_each_object(p, s, page_address(page), page->objects) check_object(s, page, p, SLUB_RED_INACTIVE); } kmemcheck_free_shadow(page, compound_order(page)); mod_zone_page_state(page_zone(page), (s->flags & SLAB_RECLAIM_ACCOUNT) ? NR_SLAB_RECLAIMABLE : NR_SLAB_UNRECLAIMABLE, -pages); __ClearPageSlabPfmemalloc(page); __ClearPageSlab(page); page_mapcount_reset(page); if (current->reclaim_state) current->reclaim_state->reclaimed_slab += pages; memcg_uncharge_slab(page, order, s); __free_pages(page, order); } #define need_reserve_slab_rcu \ (sizeof(((struct page *)NULL)->lru) < sizeof(struct rcu_head)) static void rcu_free_slab(struct rcu_head *h) { struct page *page; if (need_reserve_slab_rcu) page = virt_to_head_page(h); else page = container_of((struct list_head *)h, struct page, lru); __free_slab(page->slab_cache, page); } static void free_slab(struct kmem_cache *s, struct page *page) { if (unlikely(s->flags & SLAB_DESTROY_BY_RCU)) { struct rcu_head *head; if (need_reserve_slab_rcu) { int order = compound_order(page); int offset = (PAGE_SIZE << order) - s->reserved; VM_BUG_ON(s->reserved != sizeof(*head)); head = page_address(page) + offset; } else { head = &page->rcu_head; } call_rcu(head, rcu_free_slab); } else __free_slab(s, page); } static void discard_slab(struct kmem_cache *s, struct page *page) { dec_slabs_node(s, page_to_nid(page), page->objects); free_slab(s, page); } /* * Management of partially allocated slabs. */ static inline void __add_partial(struct kmem_cache_node *n, struct page *page, int tail) { n->nr_partial++; if (tail == DEACTIVATE_TO_TAIL) list_add_tail(&page->lru, &n->partial); else list_add(&page->lru, &n->partial); } static inline void add_partial(struct kmem_cache_node *n, struct page *page, int tail) { lockdep_assert_held(&n->list_lock); __add_partial(n, page, tail); } static inline void remove_partial(struct kmem_cache_node *n, struct page *page) { lockdep_assert_held(&n->list_lock); list_del(&page->lru); n->nr_partial--; } /* * Remove slab from the partial list, freeze it and * return the pointer to the freelist. * * Returns a list of objects or NULL if it fails. */ static inline void *acquire_slab(struct kmem_cache *s, struct kmem_cache_node *n, struct page *page, int mode, int *objects) { void *freelist; unsigned long counters; struct page new; lockdep_assert_held(&n->list_lock); /* * Zap the freelist and set the frozen bit. * The old freelist is the list of objects for the * per cpu allocation list. */ freelist = page->freelist; counters = page->counters; new.counters = counters; *objects = new.objects - new.inuse; if (mode) { new.inuse = page->objects; new.freelist = NULL; } else { new.freelist = freelist; } VM_BUG_ON(new.frozen); new.frozen = 1; if (!__cmpxchg_double_slab(s, page, freelist, counters, new.freelist, new.counters, "acquire_slab")) return NULL; remove_partial(n, page); WARN_ON(!freelist); return freelist; } static void put_cpu_partial(struct kmem_cache *s, struct page *page, int drain); static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags); /* * Try to allocate a partial slab from a specific node. */ static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n, struct kmem_cache_cpu *c, gfp_t flags) { struct page *page, *page2; void *object = NULL; unsigned int available = 0; int objects; /* * 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_partials() * will return NULL. */ if (!n || !n->nr_partial) return NULL; spin_lock(&n->list_lock); list_for_each_entry_safe(page, page2, &n->partial, lru) { void *t; if (!pfmemalloc_match(page, flags)) continue; t = acquire_slab(s, n, page, object == NULL, &objects); if (!t) break; available += objects; if (!object) { c->page = page; stat(s, ALLOC_FROM_PARTIAL); object = t; } else { put_cpu_partial(s, page, 0); stat(s, CPU_PARTIAL_NODE); } if (!kmem_cache_has_cpu_partial(s) || available > s->cpu_partial / 2) break; } spin_unlock(&n->list_lock); return object; } /* * Get a page from somewhere. Search in increasing NUMA distances. */ static void *get_any_partial(struct kmem_cache *s, gfp_t flags, struct kmem_cache_cpu *c) { #ifdef CONFIG_NUMA struct zonelist *zonelist; struct zoneref *z; struct zone *zone; enum zone_type high_zoneidx = gfp_zone(flags); void *object; 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(), flags); for_each_zone_zonelist(zone, z, zonelist, high_zoneidx) { struct kmem_cache_node *n; n = get_node(s, zone_to_nid(zone)); if (n && cpuset_zone_allowed(zone, flags) && n->nr_partial > s->min_partial) { object = get_partial_node(s, n, c, flags); if (object) { /* * 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 object; } } } } while (read_mems_allowed_retry(cpuset_mems_cookie)); #endif return NULL; } /* * Get a partial page, lock it and return it. */ static void *get_partial(struct kmem_cache *s, gfp_t flags, int node, struct kmem_cache_cpu *c) { void *object; int searchnode = node; if (node == NUMA_NO_NODE) searchnode = numa_mem_id(); object = get_partial_node(s, get_node(s, searchnode), c, flags); if (object || node != NUMA_NO_NODE) return object; return get_any_partial(s, flags, c); } #ifdef CONFIG_PREEMPT /* * Calculate the next globally unique transaction for disambiguiation * 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 static inline unsigned long next_tid(unsigned long tid) { return tid + TID_STEP; } 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; } 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_PREEMPT 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; for_each_possible_cpu(cpu) per_cpu_ptr(s->cpu_slab, cpu)->tid = init_tid(cpu); } /* * Remove the cpu slab */ static void deactivate_slab(struct kmem_cache *s, struct page *page, void *freelist) { enum slab_modes { M_NONE, M_PARTIAL, M_FULL, M_FREE }; struct kmem_cache_node *n = get_node(s, page_to_nid(page)); int lock = 0; enum slab_modes l = M_NONE, m = M_NONE; void *nextfree; int tail = DEACTIVATE_TO_HEAD; struct page new; struct page old; if (page->freelist) { stat(s, DEACTIVATE_REMOTE_FREES); tail = DEACTIVATE_TO_TAIL; } /* * Stage one: Free all available per cpu objects back * to the page freelist while it is still frozen. Leave the * last one. * * There is no need to take the list->lock because the page * is still frozen. */ while (freelist && (nextfree = get_freepointer(s, freelist))) { void *prior; unsigned long counters; /* * If 'nextfree' is invalid, it is possible that the object at * 'freelist' is already corrupted. So isolate all objects * starting at 'freelist'. */ if (freelist_corrupted(s, page, &freelist, nextfree)) break; do { prior = page->freelist; counters = page->counters; set_freepointer(s, freelist, prior); new.counters = counters; new.inuse--; VM_BUG_ON(!new.frozen); } while (!__cmpxchg_double_slab(s, page, prior, counters, freelist, new.counters, "drain percpu freelist")); freelist = nextfree; } /* * Stage two: Ensure that the page is unfrozen while the * list presence reflects the actual number of objects * during unfreeze. * * We setup the list membership and then perform a cmpxchg * with the count. If there is a mismatch then the page * is not unfrozen but the page is on the wrong list. * * Then we restart the process which may have to remove * the page from the list that we just put it on again * because the number of objects in the slab may have * changed. */ redo: old.freelist = page->freelist; old.counters = page->counters; VM_BUG_ON(!old.frozen); /* Determine target state of the slab */ new.counters = old.counters; if (freelist) { new.inuse--; set_freepointer(s, freelist, old.freelist); new.freelist = freelist; } else new.freelist = old.freelist; new.frozen = 0; if (!new.inuse && n->nr_partial >= s->min_partial) m = M_FREE; else if (new.freelist) { m = M_PARTIAL; if (!lock) { lock = 1; /* * Taking the spinlock removes the possiblity * that acquire_slab() will see a slab page that * is frozen */ spin_lock(&n->list_lock); } } else { m = M_FULL; if (kmem_cache_debug(s) && !lock) { lock = 1; /* * This also ensures that the scanning of full * slabs from diagnostic functions will not see * any frozen slabs. */ spin_lock(&n->list_lock); } } if (l != m) { if (l == M_PARTIAL) remove_partial(n, page); else if (l == M_FULL) remove_full(s, n, page); if (m == M_PARTIAL) { add_partial(n, page, tail); stat(s, tail); } else if (m == M_FULL) { stat(s, DEACTIVATE_FULL); add_full(s, n, page); } } l = m; if (!__cmpxchg_double_slab(s, page, old.freelist, old.counters, new.freelist, new.counters, "unfreezing slab")) goto redo; if (lock) spin_unlock(&n->list_lock); if (m == M_FREE) { stat(s, DEACTIVATE_EMPTY); discard_slab(s, page); stat(s, FREE_SLAB); } } /* * Unfreeze all the cpu partial slabs. * * This function must be called with interrupts disabled * for the cpu using c (or some other guarantee must be there * to guarantee no concurrent accesses). */ static void unfreeze_partials(struct kmem_cache *s, struct kmem_cache_cpu *c) { #ifdef CONFIG_SLUB_CPU_PARTIAL struct kmem_cache_node *n = NULL, *n2 = NULL; struct page *page, *discard_page = NULL; while ((page = c->partial)) { struct page new; struct page old; c->partial = page->next; n2 = get_node(s, page_to_nid(page)); if (n != n2) { if (n) spin_unlock(&n->list_lock); n = n2; spin_lock(&n->list_lock); } do { old.freelist = page->freelist; old.counters = page->counters; VM_BUG_ON(!old.frozen); new.counters = old.counters; new.freelist = old.freelist; new.frozen = 0; } while (!__cmpxchg_double_slab(s, page, old.freelist, old.counters, new.freelist, new.counters, "unfreezing slab")); if (unlikely(!new.inuse && n->nr_partial >= s->min_partial)) { page->next = discard_page; discard_page = page; } else { add_partial(n, page, DEACTIVATE_TO_TAIL); stat(s, FREE_ADD_PARTIAL); } } if (n) spin_unlock(&n->list_lock); while (discard_page) { page = discard_page; discard_page = discard_page->next; stat(s, DEACTIVATE_EMPTY); discard_slab(s, page); stat(s, FREE_SLAB); } #endif } /* * Put a page that was just frozen (in __slab_free) into a partial page * slot if available. This is done without interrupts disabled and without * preemption disabled. The cmpxchg is racy and may put the partial page * onto a random cpus partial slot. * * 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 page *page, int drain) { #ifdef CONFIG_SLUB_CPU_PARTIAL struct page *oldpage; int pages; int pobjects; preempt_disable(); do { pages = 0; pobjects = 0; oldpage = this_cpu_read(s->cpu_slab->partial); if (oldpage) { pobjects = oldpage->pobjects; pages = oldpage->pages; if (drain && pobjects > s->cpu_partial) { unsigned long flags; /* * partial array is full. Move the existing * set to the per node partial list. */ local_irq_save(flags); unfreeze_partials(s, this_cpu_ptr(s->cpu_slab)); local_irq_restore(flags); oldpage = NULL; pobjects = 0; pages = 0; stat(s, CPU_PARTIAL_DRAIN); } } pages++; pobjects += page->objects - page->inuse; page->pages = pages; page->pobjects = pobjects; page->next = oldpage; } while (this_cpu_cmpxchg(s->cpu_slab->partial, oldpage, page) != oldpage); if (unlikely(!s->cpu_partial)) { unsigned long flags; local_irq_save(flags); unfreeze_partials(s, this_cpu_ptr(s->cpu_slab)); local_irq_restore(flags); } preempt_enable(); #endif } static inline void flush_slab(struct kmem_cache *s, struct kmem_cache_cpu *c) { stat(s, CPUSLAB_FLUSH); deactivate_slab(s, c->page, c->freelist); c->tid = next_tid(c->tid); c->page = NULL; c->freelist = NULL; } /* * Flush cpu slab. * * Called from IPI handler with interrupts disabled. */ static inline void __flush_cpu_slab(struct kmem_cache *s, int cpu) { struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu); if (likely(c)) { if (c->page) flush_slab(s, c); unfreeze_partials(s, c); } } static void flush_cpu_slab(void *d) { struct kmem_cache *s = d; __flush_cpu_slab(s, smp_processor_id()); } static bool has_cpu_slab(int cpu, void *info) { struct kmem_cache *s = info; struct kmem_cache_cpu *c = per_cpu_ptr(s->cpu_slab, cpu); return c->page || c->partial; } static void flush_all(struct kmem_cache *s) { on_each_cpu_cond(has_cpu_slab, flush_cpu_slab, s, 1, GFP_ATOMIC); } /* * 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; unsigned long flags; mutex_lock(&slab_mutex); list_for_each_entry(s, &slab_caches, list) { local_irq_save(flags); __flush_cpu_slab(s, cpu); local_irq_restore(flags); } mutex_unlock(&slab_mutex); return 0; } /* * Check if the objects in a per cpu structure fit numa * locality expectations. */ static inline int node_match(struct page *page, int node) { #ifdef CONFIG_NUMA if (!page || (node != NUMA_NO_NODE && page_to_nid(page) != node)) return 0; #endif return 1; } #ifdef CONFIG_SLUB_DEBUG static int count_free(struct page *page) { return page->objects - page->inuse; } static inline unsigned long node_nr_objs(struct kmem_cache_node *n) { return atomic_long_read(&n->total_objects); } #endif /* CONFIG_SLUB_DEBUG */ #if defined(CONFIG_SLUB_DEBUG) || defined(CONFIG_SYSFS) static unsigned long count_partial(struct kmem_cache_node *n, int (*get_count)(struct page *)) { unsigned long flags; unsigned long x = 0; struct page *page; spin_lock_irqsave(&n->list_lock, flags); list_for_each_entry(page, &n->partial, lru) x += get_count(page); spin_unlock_irqrestore(&n->list_lock, flags); return x; } #endif /* CONFIG_SLUB_DEBUG || CONFIG_SYSFS */ static noinline void slab_out_of_memory(struct kmem_cache *s, gfp_t gfpflags, int nid) { #ifdef CONFIG_SLUB_DEBUG 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: %d, buffer size: %d, default order: %d, min order: %d\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 slub_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); } #endif } static inline void *new_slab_objects(struct kmem_cache *s, gfp_t flags, int node, struct kmem_cache_cpu **pc) { void *freelist; struct kmem_cache_cpu *c = *pc; struct page *page; freelist = get_partial(s, flags, node, c); if (freelist) return freelist; page = new_slab(s, flags, node); if (page) { c = raw_cpu_ptr(s->cpu_slab); if (c->page) flush_slab(s, c); /* * No other reference to the page yet so we can * muck around with it freely without cmpxchg */ freelist = page->freelist; page->freelist = NULL; stat(s, ALLOC_SLAB); c->page = page; *pc = c; } else freelist = NULL; return freelist; } static inline bool pfmemalloc_match(struct page *page, gfp_t gfpflags) { if (unlikely(PageSlabPfmemalloc(page))) return gfp_pfmemalloc_allowed(gfpflags); return true; } /* * Check the page->freelist of a page and either transfer the freelist to the * per cpu freelist or deactivate the page. * * The page is still frozen if the return value is not NULL. * * If this function returns NULL then the page has been unfrozen. * * This function must be called with interrupt disabled. */ static inline void *get_freelist(struct kmem_cache *s, struct page *page) { struct page new; unsigned long counters; void *freelist; do { freelist = page->freelist; counters = page->counters; new.counters = counters; VM_BUG_ON(!new.frozen); new.inuse = page->objects; new.frozen = freelist != NULL; } while (!__cmpxchg_double_slab(s, page, freelist, counters, NULL, new.counters, "get_freelist")); 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 interrupts are * 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) { void *freelist; struct page *page; page = c->page; if (!page) { /* * if the node is not online or has no normal memory, just * ignore the node constraint */ if (unlikely(node != NUMA_NO_NODE && !node_state(node, N_NORMAL_MEMORY))) node = NUMA_NO_NODE; goto new_slab; } redo: if (unlikely(!node_match(page, node))) { /* * same as above but node_match() being false already * implies node != NUMA_NO_NODE */ if (!node_state(node, N_NORMAL_MEMORY)) { node = NUMA_NO_NODE; goto redo; } else { stat(s, ALLOC_NODE_MISMATCH); deactivate_slab(s, page, c->freelist); c->page = NULL; c->freelist = NULL; goto new_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(page, gfpflags))) { deactivate_slab(s, page, c->freelist); c->page = NULL; c->freelist = NULL; goto new_slab; } /* must check again c->freelist in case of cpu migration or IRQ */ freelist = c->freelist; if (freelist) goto load_freelist; freelist = get_freelist(s, page); if (!freelist) { c->page = NULL; stat(s, DEACTIVATE_BYPASS); goto new_slab; } stat(s, ALLOC_REFILL); load_freelist: /* * freelist is pointing to the list of objects to be used. * page is pointing to the page from which the objects are obtained. * That page must be frozen for per cpu allocations to work. */ VM_BUG_ON(!c->page->frozen); c->freelist = get_freepointer(s, freelist); c->tid = next_tid(c->tid); return freelist; new_slab: if (c->partial) { page = c->page = c->partial; c->partial = page->next; stat(s, CPU_PARTIAL_ALLOC); c->freelist = NULL; goto redo; } freelist = new_slab_objects(s, gfpflags, node, &c); if (unlikely(!freelist)) { slab_out_of_memory(s, gfpflags, node); return NULL; } page = c->page; if (likely(!kmem_cache_debug(s) && pfmemalloc_match(page, gfpflags))) goto load_freelist; /* Only entered in the debug case */ if (kmem_cache_debug(s) && !alloc_debug_processing(s, page, freelist, addr)) goto new_slab; /* Slab failed checks. Next slab needed */ deactivate_slab(s, page, get_freepointer(s, freelist)); c->page = NULL; c->freelist = NULL; return freelist; } /* * Another one that disabled interrupt and 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) { void *p; unsigned long flags; local_irq_save(flags); #ifdef CONFIG_PREEMPT /* * We may have been preempted and rescheduled on a different * cpu before disabling interrupts. Need to reload cpu area * pointer. */ c = this_cpu_ptr(s->cpu_slab); #endif p = ___slab_alloc(s, gfpflags, node, addr, c); local_irq_restore(flags); return 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 __always_inline void *slab_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node, unsigned long addr) { void *object; struct kmem_cache_cpu *c; struct page *page; unsigned long tid; s = slab_pre_alloc_hook(s, gfpflags); if (!s) return NULL; 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 should guarantee that tid and kmem_cache are retrieved on * the same cpu. It could be different if CONFIG_PREEMPT so we need * to check if it is matched or not. */ do { tid = this_cpu_read(s->cpu_slab->tid); c = raw_cpu_ptr(s->cpu_slab); } while (IS_ENABLED(CONFIG_PREEMPT) && unlikely(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 page associated with previous tid * won't be used with current tid. If we fetch tid first, object and * page 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; page = c->page; if (unlikely(!object || !node_match(page, node))) { object = __slab_alloc(s, gfpflags, node, addr, c); stat(s, ALLOC_SLOWPATH); } 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(!this_cpu_cmpxchg_double( s->cpu_slab->freelist, s->cpu_slab->tid, object, tid, next_object, next_tid(tid)))) { note_cmpxchg_failure("slab_alloc", s, tid); goto redo; } prefetch_freepointer(s, next_object); stat(s, ALLOC_FASTPATH); } if (unlikely(gfpflags & __GFP_ZERO) && object) memset(object, 0, s->object_size); slab_post_alloc_hook(s, gfpflags, 1, &object); return object; } static __always_inline void *slab_alloc(struct kmem_cache *s, gfp_t gfpflags, unsigned long addr) { return slab_alloc_node(s, gfpflags, NUMA_NO_NODE, addr); } void *kmem_cache_alloc(struct kmem_cache *s, gfp_t gfpflags) { void *ret = slab_alloc(s, gfpflags, _RET_IP_); trace_kmem_cache_alloc(_RET_IP_, ret, s->object_size, s->size, gfpflags); return ret; } EXPORT_SYMBOL(kmem_cache_alloc); #ifdef CONFIG_TRACING void *kmem_cache_alloc_trace(struct kmem_cache *s, gfp_t gfpflags, size_t size) { void *ret = slab_alloc(s, gfpflags, _RET_IP_); trace_kmalloc(_RET_IP_, ret, size, s->size, gfpflags); kasan_kmalloc(s, ret, size, gfpflags); return ret; } EXPORT_SYMBOL(kmem_cache_alloc_trace); #endif #ifdef CONFIG_NUMA void *kmem_cache_alloc_node(struct kmem_cache *s, gfp_t gfpflags, int node) { void *ret = slab_alloc_node(s, gfpflags, node, _RET_IP_); trace_kmem_cache_alloc_node(_RET_IP_, ret, s->object_size, s->size, gfpflags, node); return ret; } EXPORT_SYMBOL(kmem_cache_alloc_node); #ifdef CONFIG_TRACING void *kmem_cache_alloc_node_trace(struct kmem_cache *s, gfp_t gfpflags, int node, size_t size) { void *ret = slab_alloc_node(s, gfpflags, node, _RET_IP_); trace_kmalloc_node(_RET_IP_, ret, size, s->size, gfpflags, node); kasan_kmalloc(s, ret, size, gfpflags); return ret; } EXPORT_SYMBOL(kmem_cache_alloc_node_trace); #endif #endif /* * 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 page * handling required then we can return immediately. */ static void __slab_free(struct kmem_cache *s, struct page *page, void *head, void *tail, int cnt, unsigned long addr) { void *prior; int was_frozen; struct page new; unsigned long counters; struct kmem_cache_node *n = NULL; unsigned long uninitialized_var(flags); stat(s, FREE_SLOWPATH); if (kmem_cache_debug(s) && !free_debug_processing(s, page, head, tail, cnt, addr)) return; do { if (unlikely(n)) { spin_unlock_irqrestore(&n->list_lock, flags); n = NULL; } prior = page->freelist; counters = page->counters; set_freepointer(s, tail, prior); new.counters = counters; was_frozen = new.frozen; new.inuse -= cnt; if ((!new.inuse || !prior) && !was_frozen) { if (kmem_cache_has_cpu_partial(s) && !prior) { /* * Slab was on no list before and will be * partially empty * We can defer the list move and instead * freeze it. */ new.frozen = 1; } else { /* Needs to be taken off a list */ n = get_node(s, page_to_nid(page)); /* * 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); } } } while (!cmpxchg_double_slab(s, page, prior, counters, head, new.counters, "__slab_free")); if (likely(!n)) { /* * If we just froze the page then put it onto the * per cpu partial list. */ if (new.frozen && !was_frozen) { put_cpu_partial(s, page, 1); stat(s, CPU_PARTIAL_FREE); } /* * The list lock was not taken therefore no list * activity can be necessary. */ if (was_frozen) stat(s, FREE_FROZEN); 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)) { if (kmem_cache_debug(s)) remove_full(s, n, page); add_partial(n, page, 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, page); stat(s, FREE_REMOVE_PARTIAL); } else { /* Slab must be on the full list */ remove_full(s, n, page); } spin_unlock_irqrestore(&n->list_lock, flags); stat(s, FREE_SLAB); discard_slab(s, page); } /* * 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 page) 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 page *page, void *head, void *tail, int cnt, unsigned long addr) { void *tail_obj = tail ? : head; struct kmem_cache_cpu *c; unsigned long tid; 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. */ do { tid = this_cpu_read(s->cpu_slab->tid); c = raw_cpu_ptr(s->cpu_slab); } while (IS_ENABLED(CONFIG_PREEMPT) && unlikely(tid != READ_ONCE(c->tid))); /* Same with comment on barrier() in slab_alloc_node() */ barrier(); if (likely(page == c->page)) { void **freelist = READ_ONCE(c->freelist); set_freepointer(s, tail_obj, freelist); if (unlikely(!this_cpu_cmpxchg_double( s->cpu_slab->freelist, s->cpu_slab->tid, freelist, tid, head, next_tid(tid)))) { note_cmpxchg_failure("slab_free", s, tid); goto redo; } stat(s, FREE_FASTPATH); } else __slab_free(s, page, head, tail_obj, cnt, addr); } static __always_inline void slab_free(struct kmem_cache *s, struct page *page, void *head, void *tail, int cnt, unsigned long addr) { slab_free_freelist_hook(s, head, tail); /* * slab_free_freelist_hook() could have put the items into quarantine. * If so, no need to free them. */ if (s->flags & SLAB_KASAN && !(s->flags & SLAB_DESTROY_BY_RCU)) return; do_slab_free(s, page, head, tail, cnt, addr); } #ifdef CONFIG_KASAN void ___cache_free(struct kmem_cache *cache, void *x, unsigned long addr) { do_slab_free(cache, virt_to_head_page(x), x, NULL, 1, addr); } #endif void kmem_cache_free(struct kmem_cache *s, void *x) { s = cache_from_obj(s, x); if (!s) return; slab_free(s, virt_to_head_page(x), x, NULL, 1, _RET_IP_); trace_kmem_cache_free(_RET_IP_, x); } EXPORT_SYMBOL(kmem_cache_free); struct detached_freelist { struct page *page; 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 * page. It builds a detached freelist directly within the given * page/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) { size_t first_skipped_index = 0; int lookahead = 3; void *object; struct page *page; /* Always re-init detached_freelist */ df->page = NULL; do { object = p[--size]; /* Do we need !ZERO_OR_NULL_PTR(object) here? (for kfree) */ } while (!object && size); if (!object) return 0; page = virt_to_head_page(object); if (!s) { /* Handle kalloc'ed objects */ if (unlikely(!PageSlab(page))) { BUG_ON(!PageCompound(page)); kfree_hook(object); __free_pages(page, compound_order(page)); p[size] = NULL; /* mark object processed */ return size; } /* Derive kmem_cache from object */ df->s = page->slab_cache; } else { df->s = cache_from_obj(s, object); /* Support for memcg */ } /* Start new detached freelist */ df->page = page; set_freepointer(df->s, object, NULL); df->tail = object; df->freelist = object; p[size] = NULL; /* mark object processed */ df->cnt = 1; while (size) { object = p[--size]; if (!object) continue; /* Skip processed objects */ /* df->page is always set at this point */ if (df->page == virt_to_head_page(object)) { /* Opportunity build freelist */ set_freepointer(df->s, object, df->freelist); df->freelist = object; df->cnt++; p[size] = NULL; /* mark object processed */ continue; } /* Limit look ahead search */ if (!--lookahead) break; if (!first_skipped_index) first_skipped_index = size + 1; } return first_skipped_index; } /* 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 (WARN_ON(!size)) return; do { struct detached_freelist df; size = build_detached_freelist(s, size, p, &df); if (unlikely(!df.page)) continue; slab_free(df.s, df.page, df.freelist, df.tail, df.cnt,_RET_IP_); } while (likely(size)); } EXPORT_SYMBOL(kmem_cache_free_bulk); /* 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) { struct kmem_cache_cpu *c; int i; /* memcg and kmem_cache debug support */ s = slab_pre_alloc_hook(s, flags); if (unlikely(!s)) return false; /* * Drain objects in the per cpu slab, while disabling local * IRQs, which protects against PREEMPT and interrupts * handlers invoking normal fastpath. */ local_irq_disable(); c = this_cpu_ptr(s->cpu_slab); for (i = 0; i < size; i++) { void *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); /* * 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); if (unlikely(!p[i])) goto error; c = this_cpu_ptr(s->cpu_slab); continue; /* goto for-loop */ } c->freelist = get_freepointer(s, object); p[i] = object; } c->tid = next_tid(c->tid); local_irq_enable(); /* Clear memory outside IRQ disabled fastpath loop */ if (unlikely(flags & __GFP_ZERO)) { int j; for (j = 0; j < i; j++) memset(p[j], 0, s->object_size); } /* memcg and kmem_cache debug support */ slab_post_alloc_hook(s, flags, size, p); return i; error: local_irq_enable(); slab_post_alloc_hook(s, flags, i, p); __kmem_cache_free_bulk(s, i, p); return 0; } 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. */ /* * Mininum / 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 int slub_min_order; static int slub_max_order = PAGE_ALLOC_COSTLY_ORDER; static 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. * * slub_max_order specifies the order where we begin to stop considering the * number of objects in a slab as critical. If we reach slub_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 mininum order then we start with that one instead of * the smallest order which will fit the object. */ static inline int slab_order(int size, int min_objects, int max_order, int fract_leftover, int reserved) { int order; int rem; int min_order = slub_min_order; if (order_objects(min_order, size, reserved) > MAX_OBJS_PER_PAGE) return get_order(size * MAX_OBJS_PER_PAGE) - 1; for (order = max(min_order, get_order(min_objects * size + reserved)); order <= max_order; order++) { unsigned long slab_size = PAGE_SIZE << order; rem = (slab_size - reserved) % size; if (rem <= slab_size / fract_leftover) break; } return order; } static inline int calculate_order(int size, int reserved) { int order; int min_objects; int fraction; int max_objects; /* * Attempt to find best configuration for a slab. This * works by first attempting to generate a layout with * the best configuration and backing off gradually. * * First we increase the acceptable waste in a slab. Then * we reduce the minimum objects required in a slab. */ min_objects = slub_min_objects; if (!min_objects) min_objects = 4 * (fls(nr_cpu_ids) + 1); max_objects = order_objects(slub_max_order, size, reserved); min_objects = min(min_objects, max_objects); while (min_objects > 1) { fraction = 16; while (fraction >= 4) { order = slab_order(size, min_objects, slub_max_order, fraction, reserved); if (order <= slub_max_order) return order; fraction /= 2; } min_objects--; } /* * We were unable to place multiple objects in a slab. Now * lets see if we can place a single object there. */ order = slab_order(size, 1, slub_max_order, 1, reserved); if (order <= slub_max_order) return order; /* * Doh this slab cannot be placed using slub_max_order. */ order = slab_order(size, 1, MAX_ORDER, 1, reserved); if (order < MAX_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 } static inline int alloc_kmem_cache_cpus(struct kmem_cache *s) { BUILD_BUG_ON(PERCPU_DYNAMIC_EARLY_SIZE < 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; } 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 page *page; struct kmem_cache_node *n; BUG_ON(kmem_cache_node->size < sizeof(struct kmem_cache_node)); page = new_slab(kmem_cache_node, GFP_NOWAIT, node); BUG_ON(!page); if (page_to_nid(page) != 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 = page->freelist; BUG_ON(!n); page->freelist = get_freepointer(kmem_cache_node, n); page->inuse = 1; page->frozen = 0; kmem_cache_node->node[node] = n; #ifdef CONFIG_SLUB_DEBUG init_object(kmem_cache_node, n, SLUB_RED_ACTIVE); init_tracking(kmem_cache_node, n); #endif kasan_kmalloc(kmem_cache_node, n, sizeof(struct kmem_cache_node), GFP_KERNEL); init_kmem_cache_node(n); inc_slabs_node(kmem_cache_node, node, page->objects); /* * No locks need to be taken here as it has just been * initialized and there is no concurrent access. */ __add_partial(n, page, 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) { kmem_cache_free(kmem_cache_node, n); s->node[node] = NULL; } } void __kmem_cache_release(struct kmem_cache *s) { cache_random_seq_destroy(s); free_percpu(s->cpu_slab); free_kmem_cache_nodes(s); } static int init_kmem_cache_nodes(struct kmem_cache *s) { int node; for_each_node_state(node, N_NORMAL_MEMORY) { 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; } s->node[node] = n; init_kmem_cache_node(n); } return 1; } static void set_min_partial(struct kmem_cache *s, unsigned long min) { if (min < MIN_PARTIAL) min = MIN_PARTIAL; else if (min > MAX_PARTIAL) min = MAX_PARTIAL; s->min_partial = min; } /* * calculate_sizes() determines the order and the distribution of data within * a slab object. */ static int calculate_sizes(struct kmem_cache *s, int forced_order) { unsigned long flags = s->flags; size_t size = s->object_size; 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_DESTROY_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. This is the potential offset to the free pointer. */ s->inuse = size; if (((flags & (SLAB_DESTROY_BY_RCU | SLAB_POISON)) || 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 or are poisoning the objects. */ s->offset = size; size += 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); #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; if (forced_order >= 0) order = forced_order; else order = calculate_order(size, s->reserved); if (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_RECLAIM_ACCOUNT) s->allocflags |= __GFP_RECLAIMABLE; /* * Determine the number of objects per slab */ s->oo = oo_make(order, size, s->reserved); s->min = oo_make(get_order(size), size, s->reserved); if (oo_objects(s->oo) > oo_objects(s->max)) s->max = s->oo; return !!oo_objects(s->oo); } static int kmem_cache_open(struct kmem_cache *s, unsigned long flags) { s->flags = kmem_cache_flags(s->size, flags, s->name, s->ctor); s->reserved = 0; if (need_reserve_slab_rcu && (s->flags & SLAB_DESTROY_BY_RCU)) s->reserved = sizeof(struct rcu_head); if (!calculate_sizes(s, -1)) 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, -1)) goto error; } } #if defined(CONFIG_HAVE_CMPXCHG_DOUBLE) && \ defined(CONFIG_HAVE_ALIGNED_STRUCT_PAGE) if (system_has_cmpxchg_double() && (s->flags & SLAB_NO_CMPXCHG) == 0) /* Enable fast mode */ s->flags |= __CMPXCHG_DOUBLE; #endif /* * The larger the object size is, the more pages we want on the partial * list to avoid pounding the page allocator excessively. */ set_min_partial(s, ilog2(s->size) / 2); /* * 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. * * This setting also determines * * A) The number of objects from per cpu partial slabs dumped to the * per node list when we reach the limit. * B) The number of objects in cpu partial slabs to extract from the * per node list when we run out of per cpu objects. We only fetch * 50% to keep some capacity around for frees. */ if (!kmem_cache_has_cpu_partial(s)) s->cpu_partial = 0; else if (s->size >= PAGE_SIZE) s->cpu_partial = 2; else if (s->size >= 1024) s->cpu_partial = 6; else if (s->size >= 256) s->cpu_partial = 13; else s->cpu_partial = 30; #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; free_kmem_cache_nodes(s); error: if (flags & SLAB_PANIC) panic("Cannot create slab %s size=%lu realsize=%u order=%u offset=%u flags=%lx\n", s->name, (unsigned long)s->size, s->size, oo_order(s->oo), s->offset, flags); return -EINVAL; } static void list_slab_objects(struct kmem_cache *s, struct page *page, const char *text) { #ifdef CONFIG_SLUB_DEBUG void *addr = page_address(page); void *p; unsigned long *map = kzalloc(BITS_TO_LONGS(page->objects) * sizeof(long), GFP_ATOMIC); if (!map) return; slab_err(s, page, text, s->name); slab_lock(page); get_map(s, page, map); for_each_object(p, s, addr, page->objects) { if (!test_bit(slab_index(p, s, addr), map)) { pr_err("INFO: Object 0x%p @offset=%tu\n", p, p - addr); print_tracking(s, p); } } slab_unlock(page); kfree(map); #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 page *page, *h; BUG_ON(irqs_disabled()); spin_lock_irq(&n->list_lock); list_for_each_entry_safe(page, h, &n->partial, lru) { if (!page->inuse) { remove_partial(n, page); list_add(&page->lru, &discard); } else { list_slab_objects(s, page, "Objects remaining in %s on __kmem_cache_shutdown()"); } } spin_unlock_irq(&n->list_lock); list_for_each_entry_safe(page, h, &discard, lru) discard_slab(s, page); } /* * 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(s); /* Attempt to free all objects */ for_each_kmem_cache_node(s, node, n) { free_partial(s, n); if (n->nr_partial || slabs_node(s, node)) return 1; } return 0; } /******************************************************************** * Kmalloc subsystem *******************************************************************/ static int __init setup_slub_min_order(char *str) { get_option(&str, &slub_min_order); return 1; } __setup("slub_min_order=", setup_slub_min_order); static int __init setup_slub_max_order(char *str) { get_option(&str, &slub_max_order); slub_max_order = min(slub_max_order, MAX_ORDER - 1); return 1; } __setup("slub_max_order=", setup_slub_max_order); static int __init setup_slub_min_objects(char *str) { get_option(&str, &slub_min_objects); return 1; } __setup("slub_min_objects=", setup_slub_min_objects); void *__kmalloc(size_t size, gfp_t flags) { struct kmem_cache *s; void *ret; if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) return kmalloc_large(size, flags); s = kmalloc_slab(size, flags); if (unlikely(ZERO_OR_NULL_PTR(s))) return s; ret = slab_alloc(s, flags, _RET_IP_); trace_kmalloc(_RET_IP_, ret, size, s->size, flags); kasan_kmalloc(s, ret, size, flags); return ret; } EXPORT_SYMBOL(__kmalloc); #ifdef CONFIG_NUMA static void *kmalloc_large_node(size_t size, gfp_t flags, int node) { struct page *page; void *ptr = NULL; flags |= __GFP_COMP | __GFP_NOTRACK; page = alloc_pages_node(node, flags, get_order(size)); if (page) ptr = page_address(page); kmalloc_large_node_hook(ptr, size, flags); return ptr; } void *__kmalloc_node(size_t size, gfp_t flags, int node) { struct kmem_cache *s; void *ret; if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) { ret = kmalloc_large_node(size, flags, node); trace_kmalloc_node(_RET_IP_, ret, size, PAGE_SIZE << get_order(size), flags, node); return ret; } s = kmalloc_slab(size, flags); if (unlikely(ZERO_OR_NULL_PTR(s))) return s; ret = slab_alloc_node(s, flags, node, _RET_IP_); trace_kmalloc_node(_RET_IP_, ret, size, s->size, flags, node); kasan_kmalloc(s, ret, size, flags); return ret; } EXPORT_SYMBOL(__kmalloc_node); #endif #ifdef CONFIG_HARDENED_USERCOPY /* * Rejects objects that are incorrectly sized. * * Returns NULL if check passes, otherwise const char * to name of cache * to indicate an error. */ const char *__check_heap_object(const void *ptr, unsigned long n, struct page *page) { struct kmem_cache *s; unsigned long offset; size_t object_size; /* Find object and usable object size. */ s = page->slab_cache; object_size = slab_ksize(s); /* Reject impossible pointers. */ if (ptr < page_address(page)) return s->name; /* Find offset within object. */ offset = (ptr - page_address(page)) % s->size; /* Adjust for redzone and reject if within the redzone. */ if (kmem_cache_debug(s) && s->flags & SLAB_RED_ZONE) { if (offset < s->red_left_pad) return s->name; offset -= s->red_left_pad; } /* Allow address range falling entirely within object size. */ if (offset <= object_size && n <= object_size - offset) return NULL; return s->name; } #endif /* CONFIG_HARDENED_USERCOPY */ static size_t __ksize(const void *object) { struct page *page; if (unlikely(object == ZERO_SIZE_PTR)) return 0; page = virt_to_head_page(object); if (unlikely(!PageSlab(page))) { WARN_ON(!PageCompound(page)); return PAGE_SIZE << compound_order(page); } return slab_ksize(page->slab_cache); } size_t ksize(const void *object) { size_t size = __ksize(object); /* We assume that ksize callers could use whole allocated area, * so we need to unpoison this area. */ kasan_unpoison_shadow(object, size); return size; } EXPORT_SYMBOL(ksize); void kfree(const void *x) { struct page *page; void *object = (void *)x; trace_kfree(_RET_IP_, x); if (unlikely(ZERO_OR_NULL_PTR(x))) return; page = virt_to_head_page(x); if (unlikely(!PageSlab(page))) { BUG_ON(!PageCompound(page)); kfree_hook(x); __free_pages(page, compound_order(page)); return; } slab_free(page->slab_cache, page, object, NULL, 1, _RET_IP_); } EXPORT_SYMBOL(kfree); #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. */ int __kmem_cache_shrink(struct kmem_cache *s) { int node; int i; struct kmem_cache_node *n; struct page *page; struct page *t; struct list_head discard; struct list_head promote[SHRINK_PROMOTE_MAX]; unsigned long flags; int ret = 0; flush_all(s); 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. page->inuse here is the upper limit. */ list_for_each_entry_safe(page, t, &n->partial, lru) { int free = page->objects - page->inuse; /* Do not reread page->inuse */ barrier(); /* We do not keep full slabs on the list */ BUG_ON(free <= 0); if (free == page->objects) { list_move(&page->lru, &discard); n->nr_partial--; } else if (free <= SHRINK_PROMOTE_MAX) list_move(&page->lru, 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(page, t, &discard, lru) discard_slab(s, page); if (slabs_node(s, node)) ret = 1; } return ret; } 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) __kmem_cache_shrink(s); mutex_unlock(&slab_mutex); return 0; } static void slab_mem_offline_callback(void *arg) { struct kmem_cache_node *n; struct kmem_cache *s; 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); list_for_each_entry(s, &slab_caches, list) { n = get_node(s, offline_node); if (n) { /* * if n->nr_slabs > 0, slabs still exist on the node * that is going down. We were unable to free them, * and offline_pages() function shouldn't call this * callback. So, we must fail. */ BUG_ON(slabs_node(s, offline_node)); s->node[offline_node] = NULL; kmem_cache_free(kmem_cache_node, n); } } 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) { /* * 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; } 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; } static struct notifier_block slab_memory_callback_nb = { .notifier_call = slab_memory_callback, .priority = SLAB_CALLBACK_PRI, }; /******************************************************************** * 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 page *p; list_for_each_entry(p, &n->partial, lru) p->slab_cache = s; #ifdef CONFIG_SLUB_DEBUG list_for_each_entry(p, &n->full, lru) p->slab_cache = s; #endif } slab_init_memcg_params(s); 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; if (debug_guardpage_minorder()) slub_max_order = 0; kmem_cache_node = &boot_kmem_cache_node; kmem_cache = &boot_kmem_cache; create_boot_cache(kmem_cache_node, "kmem_cache_node", sizeof(struct kmem_cache_node), SLAB_HWCACHE_ALIGN); register_hotmemory_notifier(&slab_memory_callback_nb); /* 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); kmem_cache = bootstrap(&boot_kmem_cache); /* * Allocate kmem_cache_node properly from the kmem_cache slab. * kmem_cache_node is separately allocated so no need to * update any list pointers. */ 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(0); /* 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=%d-%d, MinObjects=%d, CPUs=%d, Nodes=%d\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) { } struct kmem_cache * __kmem_cache_alias(const char *name, size_t size, size_t align, unsigned long flags, void (*ctor)(void *)) { struct kmem_cache *s, *c; s = find_mergeable(size, align, flags, name, ctor); if (s) { s->refcount++; /* * Adjust the object sizes so that we clear * the complete object on kzalloc. */ s->object_size = max(s->object_size, (int)size); s->inuse = max_t(int, s->inuse, ALIGN(size, sizeof(void *))); for_each_memcg_cache(c, s) { c->object_size = s->object_size; c->inuse = max_t(int, c->inuse, ALIGN(size, sizeof(void *))); } if (sysfs_slab_alias(s, name)) { s->refcount--; s = NULL; } } return s; } int __kmem_cache_create(struct kmem_cache *s, unsigned long 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; memcg_propagate_slab_attrs(s); err = sysfs_slab_add(s); if (err) __kmem_cache_release(s); return err; } void *__kmalloc_track_caller(size_t size, gfp_t gfpflags, unsigned long caller) { struct kmem_cache *s; void *ret; if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) return kmalloc_large(size, gfpflags); s = kmalloc_slab(size, gfpflags); if (unlikely(ZERO_OR_NULL_PTR(s))) return s; ret = slab_alloc(s, gfpflags, caller); /* Honor the call site pointer we received. */ trace_kmalloc(caller, ret, size, s->size, gfpflags); return ret; } #ifdef CONFIG_NUMA void *__kmalloc_node_track_caller(size_t size, gfp_t gfpflags, int node, unsigned long caller) { struct kmem_cache *s; void *ret; if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) { ret = kmalloc_large_node(size, gfpflags, node); trace_kmalloc_node(caller, ret, size, PAGE_SIZE << get_order(size), gfpflags, node); return ret; } s = kmalloc_slab(size, gfpflags); if (unlikely(ZERO_OR_NULL_PTR(s))) return s; ret = slab_alloc_node(s, gfpflags, node, caller); /* Honor the call site pointer we received. */ trace_kmalloc_node(caller, ret, size, s->size, gfpflags, node); return ret; } #endif #ifdef CONFIG_SYSFS static int count_inuse(struct page *page) { return page->inuse; } static int count_total(struct page *page) { return page->objects; } #endif #ifdef CONFIG_SLUB_DEBUG static int validate_slab(struct kmem_cache *s, struct page *page, unsigned long *map) { void *p; void *addr = page_address(page); if (!check_slab(s, page) || !on_freelist(s, page, NULL)) return 0; /* Now we know that a valid freelist exists */ bitmap_zero(map, page->objects); get_map(s, page, map); for_each_object(p, s, addr, page->objects) { if (test_bit(slab_index(p, s, addr), map)) if (!check_object(s, page, p, SLUB_RED_INACTIVE)) return 0; } for_each_object(p, s, addr, page->objects) if (!test_bit(slab_index(p, s, addr), map)) if (!check_object(s, page, p, SLUB_RED_ACTIVE)) return 0; return 1; } static void validate_slab_slab(struct kmem_cache *s, struct page *page, unsigned long *map) { slab_lock(page); validate_slab(s, page, map); slab_unlock(page); } static int validate_slab_node(struct kmem_cache *s, struct kmem_cache_node *n, unsigned long *map) { unsigned long count = 0; struct page *page; unsigned long flags; spin_lock_irqsave(&n->list_lock, flags); list_for_each_entry(page, &n->partial, lru) { validate_slab_slab(s, page, 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); if (!(s->flags & SLAB_STORE_USER)) goto out; list_for_each_entry(page, &n->full, lru) { validate_slab_slab(s, page, map); count++; } if (count != atomic_long_read(&n->nr_slabs)) pr_err("SLUB: %s %ld slabs counted but counter=%ld\n", s->name, count, atomic_long_read(&n->nr_slabs)); out: spin_unlock_irqrestore(&n->list_lock, flags); return count; } static long validate_slab_cache(struct kmem_cache *s) { int node; unsigned long count = 0; unsigned long *map = kmalloc(BITS_TO_LONGS(oo_objects(s->max)) * sizeof(unsigned long), GFP_KERNEL); struct kmem_cache_node *n; if (!map) return -ENOMEM; flush_all(s); for_each_kmem_cache_node(s, node, n) count += validate_slab_node(s, n, map); kfree(map); return count; } /* * Generate lists of code addresses where slabcache objects are allocated * and freed. */ struct location { unsigned long count; unsigned long addr; 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; }; 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) { long start, end, pos; struct location *l; unsigned long caddr; unsigned long age = jiffies - track->when; 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; caddr = t->loc[pos].addr; if (track->addr == caddr) { l = &t->loc[pos]; 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 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; 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 page *page, enum track_item alloc, unsigned long *map) { void *addr = page_address(page); void *p; bitmap_zero(map, page->objects); get_map(s, page, map); for_each_object(p, s, addr, page->objects) if (!test_bit(slab_index(p, s, addr), map)) add_location(t, s, get_track(s, p, alloc)); } static int list_locations(struct kmem_cache *s, char *buf, enum track_item alloc) { int len = 0; unsigned long i; struct loc_track t = { 0, 0, NULL }; int node; unsigned long *map = kmalloc(BITS_TO_LONGS(oo_objects(s->max)) * sizeof(unsigned long), GFP_KERNEL); struct kmem_cache_node *n; if (!map || !alloc_loc_track(&t, PAGE_SIZE / sizeof(struct location), GFP_TEMPORARY)) { kfree(map); return sprintf(buf, "Out of memory\n"); } /* Push back cpu slabs */ flush_all(s); for_each_kmem_cache_node(s, node, n) { unsigned long flags; struct page *page; if (!atomic_long_read(&n->nr_slabs)) continue; spin_lock_irqsave(&n->list_lock, flags); list_for_each_entry(page, &n->partial, lru) process_slab(&t, s, page, alloc, map); list_for_each_entry(page, &n->full, lru) process_slab(&t, s, page, alloc, map); spin_unlock_irqrestore(&n->list_lock, flags); } for (i = 0; i < t.count; i++) { struct location *l = &t.loc[i]; if (len > PAGE_SIZE - KSYM_SYMBOL_LEN - 100) break; len += sprintf(buf + len, "%7ld ", l->count); if (l->addr) len += sprintf(buf + len, "%pS", (void *)l->addr); else len += sprintf(buf + len, ""); if (l->sum_time != l->min_time) { len += sprintf(buf + len, " age=%ld/%ld/%ld", l->min_time, (long)div_u64(l->sum_time, l->count), l->max_time); } else len += sprintf(buf + len, " age=%ld", l->min_time); if (l->min_pid != l->max_pid) len += sprintf(buf + len, " pid=%ld-%ld", l->min_pid, l->max_pid); else len += sprintf(buf + len, " pid=%ld", l->min_pid); if (num_online_cpus() > 1 && !cpumask_empty(to_cpumask(l->cpus)) && len < PAGE_SIZE - 60) len += scnprintf(buf + len, PAGE_SIZE - len - 50, " cpus=%*pbl", cpumask_pr_args(to_cpumask(l->cpus))); if (nr_online_nodes > 1 && !nodes_empty(l->nodes) && len < PAGE_SIZE - 60) len += scnprintf(buf + len, PAGE_SIZE - len - 50, " nodes=%*pbl", nodemask_pr_args(&l->nodes)); len += sprintf(buf + len, "\n"); } free_loc_track(&t); kfree(map); if (!t.count) len += sprintf(buf, "No data\n"); return len; } #endif #ifdef SLUB_RESILIENCY_TEST static void __init resiliency_test(void) { u8 *p; BUILD_BUG_ON(KMALLOC_MIN_SIZE > 16 || KMALLOC_SHIFT_HIGH < 10); pr_err("SLUB resiliency testing\n"); pr_err("-----------------------\n"); pr_err("A. Corruption after allocation\n"); p = kzalloc(16, GFP_KERNEL); p[16] = 0x12; pr_err("\n1. kmalloc-16: Clobber Redzone/next pointer 0x12->0x%p\n\n", p + 16); validate_slab_cache(kmalloc_caches[4]); /* Hmmm... The next two are dangerous */ p = kzalloc(32, GFP_KERNEL); p[32 + sizeof(void *)] = 0x34; pr_err("\n2. kmalloc-32: Clobber next pointer/next slab 0x34 -> -0x%p\n", p); pr_err("If allocated object is overwritten then not detectable\n\n"); validate_slab_cache(kmalloc_caches[5]); p = kzalloc(64, GFP_KERNEL); p += 64 + (get_cycles() & 0xff) * sizeof(void *); *p = 0x56; pr_err("\n3. kmalloc-64: corrupting random byte 0x56->0x%p\n", p); pr_err("If allocated object is overwritten then not detectable\n\n"); validate_slab_cache(kmalloc_caches[6]); pr_err("\nB. Corruption after free\n"); p = kzalloc(128, GFP_KERNEL); kfree(p); *p = 0x78; pr_err("1. kmalloc-128: Clobber first word 0x78->0x%p\n\n", p); validate_slab_cache(kmalloc_caches[7]); p = kzalloc(256, GFP_KERNEL); kfree(p); p[50] = 0x9a; pr_err("\n2. kmalloc-256: Clobber 50th byte 0x9a->0x%p\n\n", p); validate_slab_cache(kmalloc_caches[8]); p = kzalloc(512, GFP_KERNEL); kfree(p); p[512] = 0xab; pr_err("\n3. kmalloc-512: Clobber redzone 0xab->0x%p\n\n", p); validate_slab_cache(kmalloc_caches[9]); } #else #ifdef CONFIG_SYSFS static void resiliency_test(void) {}; #endif #endif #ifdef CONFIG_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; nodes = kzalloc(sizeof(unsigned long) * nr_node_ids, 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 page *page; page = READ_ONCE(c->page); if (!page) continue; node = page_to_nid(page); if (flags & SO_TOTAL) x = page->objects; else if (flags & SO_OBJECTS) x = page->inuse; else x = 1; total += x; nodes[node] += x; page = READ_ONCE(c->partial); if (page) { node = page_to_nid(page); if (flags & SO_TOTAL) WARN_ON_ONCE(1); else if (flags & SO_OBJECTS) WARN_ON_ONCE(1); else x = page->pages; total += x; nodes[node] += x; } } } /* * 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 = atomic_long_read(&n->total_objects); else if (flags & SO_OBJECTS) x = atomic_long_read(&n->total_objects) - count_partial(n, count_free); else x = atomic_long_read(&n->nr_slabs); 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; } } x = sprintf(buf, "%lu", total); #ifdef CONFIG_NUMA for (node = 0; node < nr_node_ids; node++) if (nodes[node]) x += sprintf(buf + x, " N%d=%lu", node, nodes[node]); #endif kfree(nodes); return x + sprintf(buf + x, "\n"); } #ifdef CONFIG_SLUB_DEBUG static int any_slab_objects(struct kmem_cache *s) { int node; struct kmem_cache_node *n; for_each_kmem_cache_node(s, node, n) if (atomic_long_read(&n->total_objects)) return 1; return 0; } #endif #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(_name, 0400, _name##_show, NULL) #define SLAB_ATTR(_name) \ static struct slab_attribute _name##_attr = \ __ATTR(_name, 0600, _name##_show, _name##_store) static ssize_t slab_size_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%d\n", s->size); } SLAB_ATTR_RO(slab_size); static ssize_t align_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%d\n", s->align); } SLAB_ATTR_RO(align); static ssize_t object_size_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%d\n", s->object_size); } SLAB_ATTR_RO(object_size); static ssize_t objs_per_slab_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%d\n", oo_objects(s->oo)); } SLAB_ATTR_RO(objs_per_slab); static ssize_t order_store(struct kmem_cache *s, const char *buf, size_t length) { unsigned long order; int err; err = kstrtoul(buf, 10, &order); if (err) return err; if (order > slub_max_order || order < slub_min_order) return -EINVAL; calculate_sizes(s, order); return length; } static ssize_t order_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%d\n", oo_order(s->oo)); } SLAB_ATTR(order); static ssize_t min_partial_show(struct kmem_cache *s, char *buf) { return sprintf(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; set_min_partial(s, min); return length; } SLAB_ATTR(min_partial); static ssize_t cpu_partial_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%u\n", s->cpu_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; s->cpu_partial = 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 sprintf(buf, "%pS\n", s->ctor); } SLAB_ATTR_RO(ctor); static ssize_t aliases_show(struct kmem_cache *s, char *buf) { return sprintf(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_show(struct kmem_cache *s, char *buf) { return show_slab_objects(s, buf, SO_ALL|SO_OBJECTS); } SLAB_ATTR_RO(objects); 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 pages = 0; int cpu; int len; for_each_online_cpu(cpu) { struct page *page = per_cpu_ptr(s->cpu_slab, cpu)->partial; if (page) { pages += page->pages; objects += page->pobjects; } } len = sprintf(buf, "%d(%d)", objects, pages); #ifdef CONFIG_SMP for_each_online_cpu(cpu) { struct page *page = per_cpu_ptr(s->cpu_slab, cpu) ->partial; if (page && len < PAGE_SIZE - 20) len += sprintf(buf + len, " C%d=%d(%d)", cpu, page->pobjects, page->pages); } #endif return len + sprintf(buf + len, "\n"); } SLAB_ATTR_RO(slabs_cpu_partial); static ssize_t reclaim_account_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%d\n", !!(s->flags & SLAB_RECLAIM_ACCOUNT)); } static ssize_t reclaim_account_store(struct kmem_cache *s, const char *buf, size_t length) { s->flags &= ~SLAB_RECLAIM_ACCOUNT; if (buf[0] == '1') s->flags |= SLAB_RECLAIM_ACCOUNT; return length; } SLAB_ATTR(reclaim_account); static ssize_t hwcache_align_show(struct kmem_cache *s, char *buf) { return sprintf(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 sprintf(buf, "%d\n", !!(s->flags & SLAB_CACHE_DMA)); } SLAB_ATTR_RO(cache_dma); #endif static ssize_t destroy_by_rcu_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%d\n", !!(s->flags & SLAB_DESTROY_BY_RCU)); } SLAB_ATTR_RO(destroy_by_rcu); static ssize_t reserved_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%d\n", s->reserved); } SLAB_ATTR_RO(reserved); #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 sanity_checks_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%d\n", !!(s->flags & SLAB_CONSISTENCY_CHECKS)); } static ssize_t sanity_checks_store(struct kmem_cache *s, const char *buf, size_t length) { s->flags &= ~SLAB_CONSISTENCY_CHECKS; if (buf[0] == '1') { s->flags &= ~__CMPXCHG_DOUBLE; s->flags |= SLAB_CONSISTENCY_CHECKS; } return length; } SLAB_ATTR(sanity_checks); static ssize_t trace_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%d\n", !!(s->flags & SLAB_TRACE)); } static ssize_t trace_store(struct kmem_cache *s, const char *buf, size_t length) { /* * Tracing a merged cache is going to give confusing results * as well as cause other issues like converting a mergeable * cache into an umergeable one. */ if (s->refcount > 1) return -EINVAL; s->flags &= ~SLAB_TRACE; if (buf[0] == '1') { s->flags &= ~__CMPXCHG_DOUBLE; s->flags |= SLAB_TRACE; } return length; } SLAB_ATTR(trace); static ssize_t red_zone_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%d\n", !!(s->flags & SLAB_RED_ZONE)); } static ssize_t red_zone_store(struct kmem_cache *s, const char *buf, size_t length) { if (any_slab_objects(s)) return -EBUSY; s->flags &= ~SLAB_RED_ZONE; if (buf[0] == '1') { s->flags |= SLAB_RED_ZONE; } calculate_sizes(s, -1); return length; } SLAB_ATTR(red_zone); static ssize_t poison_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%d\n", !!(s->flags & SLAB_POISON)); } static ssize_t poison_store(struct kmem_cache *s, const char *buf, size_t length) { if (any_slab_objects(s)) return -EBUSY; s->flags &= ~SLAB_POISON; if (buf[0] == '1') { s->flags |= SLAB_POISON; } calculate_sizes(s, -1); return length; } SLAB_ATTR(poison); static ssize_t store_user_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%d\n", !!(s->flags & SLAB_STORE_USER)); } static ssize_t store_user_store(struct kmem_cache *s, const char *buf, size_t length) { if (any_slab_objects(s)) return -EBUSY; s->flags &= ~SLAB_STORE_USER; if (buf[0] == '1') { s->flags &= ~__CMPXCHG_DOUBLE; s->flags |= SLAB_STORE_USER; } calculate_sizes(s, -1); return length; } SLAB_ATTR(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') { ret = validate_slab_cache(s); if (ret >= 0) ret = length; } return ret; } SLAB_ATTR(validate); static ssize_t alloc_calls_show(struct kmem_cache *s, char *buf) { if (!(s->flags & SLAB_STORE_USER)) return -ENOSYS; return list_locations(s, buf, TRACK_ALLOC); } SLAB_ATTR_RO(alloc_calls); static ssize_t free_calls_show(struct kmem_cache *s, char *buf) { if (!(s->flags & SLAB_STORE_USER)) return -ENOSYS; return list_locations(s, buf, TRACK_FREE); } SLAB_ATTR_RO(free_calls); #endif /* CONFIG_SLUB_DEBUG */ #ifdef CONFIG_FAILSLAB static ssize_t failslab_show(struct kmem_cache *s, char *buf) { return sprintf(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; s->flags &= ~SLAB_FAILSLAB; if (buf[0] == '1') 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 sprintf(buf, "%d\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 long ratio; int err; err = kstrtoul(buf, 10, &ratio); if (err) return err; if (ratio <= 100) 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; int *data = kmalloc(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 = sprintf(buf, "%lu", sum); #ifdef CONFIG_SMP for_each_online_cpu(cpu) { if (data[cpu] && len < PAGE_SIZE - 20) len += sprintf(buf + len, " C%d=%u", cpu, data[cpu]); } #endif kfree(data); return len + sprintf(buf + len, "\n"); } 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 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_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, &reserved_attr.attr, &slabs_cpu_partial_attr.attr, #ifdef CONFIG_SLUB_DEBUG &total_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, &alloc_calls_attr.attr, &free_calls_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 NULL }; static 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; int err; attribute = to_slab_attr(attr); s = to_slab(kobj); if (!attribute->show) return -EIO; err = attribute->show(s, buf); return err; } 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; int err; attribute = to_slab_attr(attr); s = to_slab(kobj); if (!attribute->store) return -EIO; err = attribute->store(s, buf, len); #ifdef CONFIG_MEMCG if (slab_state >= FULL && err >= 0 && is_root_cache(s)) { struct kmem_cache *c; mutex_lock(&slab_mutex); if (s->max_attr_size < len) s->max_attr_size = len; /* * This is a best effort propagation, so this function's return * value will be determined by the parent cache only. This is * basically because not all attributes will have a well * defined semantics for rollbacks - most of the actions will * have permanent effects. * * Returning the error value of any of the children that fail * is not 100 % defined, in the sense that users seeing the * error code won't be able to know anything about the state of * the cache. * * Only returning the error code for the parent cache at least * has well defined semantics. The cache being written to * directly either failed or succeeded, in which case we loop * through the descendants with best-effort propagation. */ for_each_memcg_cache(c, s) attribute->store(c, buf, len); mutex_unlock(&slab_mutex); } #endif return err; } static void memcg_propagate_slab_attrs(struct kmem_cache *s) { #ifdef CONFIG_MEMCG int i; char *buffer = NULL; struct kmem_cache *root_cache; if (is_root_cache(s)) return; root_cache = s->memcg_params.root_cache; /* * This mean this cache had no attribute written. Therefore, no point * in copying default values around */ if (!root_cache->max_attr_size) return; for (i = 0; i < ARRAY_SIZE(slab_attrs); i++) { char mbuf[64]; char *buf; struct slab_attribute *attr = to_slab_attr(slab_attrs[i]); ssize_t len; if (!attr || !attr->store || !attr->show) continue; /* * It is really bad that we have to allocate here, so we will * do it only as a fallback. If we actually allocate, though, * we can just use the allocated buffer until the end. * * Most of the slub attributes will tend to be very small in * size, but sysfs allows buffers up to a page, so they can * theoretically happen. */ if (buffer) buf = buffer; else if (root_cache->max_attr_size < ARRAY_SIZE(mbuf) && !IS_ENABLED(CONFIG_SLUB_STATS)) buf = mbuf; else { buffer = (char *) get_zeroed_page(GFP_KERNEL); if (WARN_ON(!buffer)) continue; buf = buffer; } len = attr->show(root_cache, buf); if (len > 0) attr->store(s, buf, len); } if (buffer) free_page((unsigned long)buffer); #endif } 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 struct kobj_type slab_ktype = { .sysfs_ops = &slab_sysfs_ops, .release = kmem_cache_release, }; static int uevent_filter(struct kset *kset, struct kobject *kobj) { struct kobj_type *ktype = get_ktype(kobj); if (ktype == &slab_ktype) return 1; return 0; } static const struct kset_uevent_ops slab_uevent_ops = { .filter = uevent_filter, }; static struct kset *slab_kset; static inline struct kset *cache_kset(struct kmem_cache *s) { #ifdef CONFIG_MEMCG if (!is_root_cache(s)) return s->memcg_params.root_cache->memcg_kset; #endif return slab_kset; } #define ID_STR_LENGTH 64 /* 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; BUG_ON(!name); *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_RECLAIM_ACCOUNT) *p++ = 'a'; if (s->flags & SLAB_CONSISTENCY_CHECKS) *p++ = 'F'; if (!(s->flags & SLAB_NOTRACK)) *p++ = 't'; if (s->flags & SLAB_ACCOUNT) *p++ = 'A'; if (p != name + 1) *p++ = '-'; p += sprintf(p, "%07d", s->size); BUG_ON(p > name + ID_STR_LENGTH - 1); return name; } static int sysfs_slab_add(struct kmem_cache *s) { int err; const char *name; int unmergeable = slab_unmergeable(s); 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); } s->kobj.kset = cache_kset(s); err = kobject_init_and_add(&s->kobj, &slab_ktype, NULL, "%s", name); if (err) { kobject_put(&s->kobj); goto out; } err = sysfs_create_group(&s->kobj, &slab_attr_group); if (err) goto out_del_kobj; #ifdef CONFIG_MEMCG if (is_root_cache(s)) { s->memcg_kset = kset_create_and_add("cgroup", NULL, &s->kobj); if (!s->memcg_kset) { err = -ENOMEM; goto out_del_kobj; } } #endif kobject_uevent(&s->kobj, KOBJ_ADD); 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_remove(struct kmem_cache *s) { if (slab_state < FULL) /* * Sysfs has not been setup yet so no need to remove the * cache from sysfs. */ return; #ifdef CONFIG_MEMCG kset_unregister(s->memcg_kset); #endif kobject_uevent(&s->kobj, KOBJ_REMOVE); kobject_del(&s->kobj); 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; 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", &slab_uevent_ops, kernel_kobj); if (!slab_kset) { mutex_unlock(&slab_mutex); pr_err("Cannot register slab subsystem.\n"); return -ENOSYS; } 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); resiliency_test(); return 0; } __initcall(slab_sysfs_init); #endif /* CONFIG_SYSFS */ /* * The /proc/slabinfo ABI */ #ifdef CONFIG_SLABINFO 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_SLABINFO */