diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-08 10:34:39 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-08 10:34:39 -0700 |
commit | 6b37754790067c9b25cf75fbf72b69edd6d7fffd (patch) | |
tree | ae2c5677635cff008287390070d0701dc976455e | |
parent | 1758feddb0f9751debdc865fefde94b45907c948 (diff) | |
parent | d5f34153e526903abe71869dbbc898bfc0f69373 (diff) | |
download | linux-6b37754790067c9b25cf75fbf72b69edd6d7fffd.tar.bz2 |
Merge branch 'core-debugobjects-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull debugobjects updates from Thomas Gleixner:
"A set of updates for debugobjects:
- A series of changes to make debugobjects more scalable by
introducing per cpu pools and reducing the number of lock
acquisitions
- debugfs cleanup"
* 'core-debugobjects-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
debugobjects: Move printk out of db->lock critical sections
debugobjects: Less aggressive freeing of excess debug objects
debugobjects: Reduce number of pool_lock acquisitions in fill_pool()
debugobjects: Percpu pool lookahead freeing/allocation
debugobjects: Add percpu free pools
debugobjects: No need to check return value of debugfs_create()
-rw-r--r-- | lib/debugobjects.c | 321 |
1 files changed, 253 insertions, 68 deletions
diff --git a/lib/debugobjects.c b/lib/debugobjects.c index 55437fd5128b..61261195f5b6 100644 --- a/lib/debugobjects.c +++ b/lib/debugobjects.c @@ -25,16 +25,37 @@ #define ODEBUG_POOL_SIZE 1024 #define ODEBUG_POOL_MIN_LEVEL 256 +#define ODEBUG_POOL_PERCPU_SIZE 64 +#define ODEBUG_BATCH_SIZE 16 #define ODEBUG_CHUNK_SHIFT PAGE_SHIFT #define ODEBUG_CHUNK_SIZE (1 << ODEBUG_CHUNK_SHIFT) #define ODEBUG_CHUNK_MASK (~(ODEBUG_CHUNK_SIZE - 1)) +/* + * We limit the freeing of debug objects via workqueue at a maximum + * frequency of 10Hz and about 1024 objects for each freeing operation. + * So it is freeing at most 10k debug objects per second. + */ +#define ODEBUG_FREE_WORK_MAX 1024 +#define ODEBUG_FREE_WORK_DELAY DIV_ROUND_UP(HZ, 10) + struct debug_bucket { struct hlist_head list; raw_spinlock_t lock; }; +/* + * Debug object percpu free list + * Access is protected by disabling irq + */ +struct debug_percpu_free { + struct hlist_head free_objs; + int obj_free; +}; + +static DEFINE_PER_CPU(struct debug_percpu_free, percpu_obj_pool); + static struct debug_bucket obj_hash[ODEBUG_HASH_SIZE]; static struct debug_obj obj_static_pool[ODEBUG_POOL_SIZE] __initdata; @@ -44,13 +65,20 @@ static DEFINE_RAW_SPINLOCK(pool_lock); static HLIST_HEAD(obj_pool); static HLIST_HEAD(obj_to_free); +/* + * Because of the presence of percpu free pools, obj_pool_free will + * under-count those in the percpu free pools. Similarly, obj_pool_used + * will over-count those in the percpu free pools. Adjustments will be + * made at debug_stats_show(). Both obj_pool_min_free and obj_pool_max_used + * can be off. + */ static int obj_pool_min_free = ODEBUG_POOL_SIZE; static int obj_pool_free = ODEBUG_POOL_SIZE; static int obj_pool_used; static int obj_pool_max_used; +static bool obj_freeing; /* The number of objs on the global free list */ static int obj_nr_tofree; -static struct kmem_cache *obj_cache; static int debug_objects_maxchain __read_mostly; static int __maybe_unused debug_objects_maxchecked __read_mostly; @@ -63,6 +91,7 @@ static int debug_objects_pool_size __read_mostly static int debug_objects_pool_min_level __read_mostly = ODEBUG_POOL_MIN_LEVEL; static struct debug_obj_descr *descr_test __read_mostly; +static struct kmem_cache *obj_cache __read_mostly; /* * Track numbers of kmem_cache_alloc()/free() calls done. @@ -71,7 +100,7 @@ static int debug_objects_allocated; static int debug_objects_freed; static void free_obj_work(struct work_struct *work); -static DECLARE_WORK(debug_obj_work, free_obj_work); +static DECLARE_DELAYED_WORK(debug_obj_work, free_obj_work); static int __init enable_object_debug(char *str) { @@ -100,7 +129,7 @@ static const char *obj_states[ODEBUG_STATE_MAX] = { static void fill_pool(void) { gfp_t gfp = GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN; - struct debug_obj *new, *obj; + struct debug_obj *obj; unsigned long flags; if (likely(obj_pool_free >= debug_objects_pool_min_level)) @@ -116,7 +145,7 @@ static void fill_pool(void) * Recheck with the lock held as the worker thread might have * won the race and freed the global free list already. */ - if (obj_nr_tofree) { + while (obj_nr_tofree && (obj_pool_free < obj_pool_min_free)) { obj = hlist_entry(obj_to_free.first, typeof(*obj), node); hlist_del(&obj->node); obj_nr_tofree--; @@ -130,15 +159,23 @@ static void fill_pool(void) return; while (obj_pool_free < debug_objects_pool_min_level) { + struct debug_obj *new[ODEBUG_BATCH_SIZE]; + int cnt; - new = kmem_cache_zalloc(obj_cache, gfp); - if (!new) + for (cnt = 0; cnt < ODEBUG_BATCH_SIZE; cnt++) { + new[cnt] = kmem_cache_zalloc(obj_cache, gfp); + if (!new[cnt]) + break; + } + if (!cnt) return; raw_spin_lock_irqsave(&pool_lock, flags); - hlist_add_head(&new->node, &obj_pool); - debug_objects_allocated++; - obj_pool_free++; + while (cnt) { + hlist_add_head(&new[--cnt]->node, &obj_pool); + debug_objects_allocated++; + obj_pool_free++; + } raw_spin_unlock_irqrestore(&pool_lock, flags); } } @@ -163,36 +200,81 @@ static struct debug_obj *lookup_object(void *addr, struct debug_bucket *b) } /* + * Allocate a new object from the hlist + */ +static struct debug_obj *__alloc_object(struct hlist_head *list) +{ + struct debug_obj *obj = NULL; + + if (list->first) { + obj = hlist_entry(list->first, typeof(*obj), node); + hlist_del(&obj->node); + } + + return obj; +} + +/* * Allocate a new object. If the pool is empty, switch off the debugger. * Must be called with interrupts disabled. */ static struct debug_obj * alloc_object(void *addr, struct debug_bucket *b, struct debug_obj_descr *descr) { - struct debug_obj *obj = NULL; + struct debug_percpu_free *percpu_pool = this_cpu_ptr(&percpu_obj_pool); + struct debug_obj *obj; - raw_spin_lock(&pool_lock); - if (obj_pool.first) { - obj = hlist_entry(obj_pool.first, typeof(*obj), node); + if (likely(obj_cache)) { + obj = __alloc_object(&percpu_pool->free_objs); + if (obj) { + percpu_pool->obj_free--; + goto init_obj; + } + } - obj->object = addr; - obj->descr = descr; - obj->state = ODEBUG_STATE_NONE; - obj->astate = 0; - hlist_del(&obj->node); + raw_spin_lock(&pool_lock); + obj = __alloc_object(&obj_pool); + if (obj) { + obj_pool_used++; + obj_pool_free--; - hlist_add_head(&obj->node, &b->list); + /* + * Looking ahead, allocate one batch of debug objects and + * put them into the percpu free pool. + */ + if (likely(obj_cache)) { + int i; + + for (i = 0; i < ODEBUG_BATCH_SIZE; i++) { + struct debug_obj *obj2; + + obj2 = __alloc_object(&obj_pool); + if (!obj2) + break; + hlist_add_head(&obj2->node, + &percpu_pool->free_objs); + percpu_pool->obj_free++; + obj_pool_used++; + obj_pool_free--; + } + } - obj_pool_used++; if (obj_pool_used > obj_pool_max_used) obj_pool_max_used = obj_pool_used; - obj_pool_free--; if (obj_pool_free < obj_pool_min_free) obj_pool_min_free = obj_pool_free; } raw_spin_unlock(&pool_lock); +init_obj: + if (obj) { + obj->object = addr; + obj->descr = descr; + obj->state = ODEBUG_STATE_NONE; + obj->astate = 0; + hlist_add_head(&obj->node, &b->list); + } return obj; } @@ -209,13 +291,19 @@ static void free_obj_work(struct work_struct *work) unsigned long flags; HLIST_HEAD(tofree); + WRITE_ONCE(obj_freeing, false); if (!raw_spin_trylock_irqsave(&pool_lock, flags)) return; + if (obj_pool_free >= debug_objects_pool_size) + goto free_objs; + /* * The objs on the pool list might be allocated before the work is * run, so recheck if pool list it full or not, if not fill pool - * list from the global free list + * list from the global free list. As it is likely that a workload + * may be gearing up to use more and more objects, don't free any + * of them until the next round. */ while (obj_nr_tofree && obj_pool_free < debug_objects_pool_size) { obj = hlist_entry(obj_to_free.first, typeof(*obj), node); @@ -224,7 +312,10 @@ static void free_obj_work(struct work_struct *work) obj_pool_free++; obj_nr_tofree--; } + raw_spin_unlock_irqrestore(&pool_lock, flags); + return; +free_objs: /* * Pool list is already full and there are still objs on the free * list. Move remaining free objs to a temporary list to free the @@ -243,24 +334,86 @@ static void free_obj_work(struct work_struct *work) } } -static bool __free_object(struct debug_obj *obj) +static void __free_object(struct debug_obj *obj) { + struct debug_obj *objs[ODEBUG_BATCH_SIZE]; + struct debug_percpu_free *percpu_pool; + int lookahead_count = 0; unsigned long flags; bool work; - raw_spin_lock_irqsave(&pool_lock, flags); - work = (obj_pool_free > debug_objects_pool_size) && obj_cache; + local_irq_save(flags); + if (!obj_cache) + goto free_to_obj_pool; + + /* + * Try to free it into the percpu pool first. + */ + percpu_pool = this_cpu_ptr(&percpu_obj_pool); + if (percpu_pool->obj_free < ODEBUG_POOL_PERCPU_SIZE) { + hlist_add_head(&obj->node, &percpu_pool->free_objs); + percpu_pool->obj_free++; + local_irq_restore(flags); + return; + } + + /* + * As the percpu pool is full, look ahead and pull out a batch + * of objects from the percpu pool and free them as well. + */ + for (; lookahead_count < ODEBUG_BATCH_SIZE; lookahead_count++) { + objs[lookahead_count] = __alloc_object(&percpu_pool->free_objs); + if (!objs[lookahead_count]) + break; + percpu_pool->obj_free--; + } + +free_to_obj_pool: + raw_spin_lock(&pool_lock); + work = (obj_pool_free > debug_objects_pool_size) && obj_cache && + (obj_nr_tofree < ODEBUG_FREE_WORK_MAX); obj_pool_used--; if (work) { obj_nr_tofree++; hlist_add_head(&obj->node, &obj_to_free); + if (lookahead_count) { + obj_nr_tofree += lookahead_count; + obj_pool_used -= lookahead_count; + while (lookahead_count) { + hlist_add_head(&objs[--lookahead_count]->node, + &obj_to_free); + } + } + + if ((obj_pool_free > debug_objects_pool_size) && + (obj_nr_tofree < ODEBUG_FREE_WORK_MAX)) { + int i; + + /* + * Free one more batch of objects from obj_pool. + */ + for (i = 0; i < ODEBUG_BATCH_SIZE; i++) { + obj = __alloc_object(&obj_pool); + hlist_add_head(&obj->node, &obj_to_free); + obj_pool_free--; + obj_nr_tofree++; + } + } } else { obj_pool_free++; hlist_add_head(&obj->node, &obj_pool); + if (lookahead_count) { + obj_pool_free += lookahead_count; + obj_pool_used -= lookahead_count; + while (lookahead_count) { + hlist_add_head(&objs[--lookahead_count]->node, + &obj_pool); + } + } } - raw_spin_unlock_irqrestore(&pool_lock, flags); - return work; + raw_spin_unlock(&pool_lock); + local_irq_restore(flags); } /* @@ -269,8 +422,11 @@ static bool __free_object(struct debug_obj *obj) */ static void free_object(struct debug_obj *obj) { - if (__free_object(obj)) - schedule_work(&debug_obj_work); + __free_object(obj); + if (!obj_freeing && obj_nr_tofree) { + WRITE_ONCE(obj_freeing, true); + schedule_delayed_work(&debug_obj_work, ODEBUG_FREE_WORK_DELAY); + } } /* @@ -372,6 +528,7 @@ static void __debug_object_init(void *addr, struct debug_obj_descr *descr, int onstack) { enum debug_obj_state state; + bool check_stack = false; struct debug_bucket *db; struct debug_obj *obj; unsigned long flags; @@ -391,7 +548,7 @@ __debug_object_init(void *addr, struct debug_obj_descr *descr, int onstack) debug_objects_oom(); return; } - debug_object_is_on_stack(addr, onstack); + check_stack = true; } switch (obj->state) { @@ -402,20 +559,23 @@ __debug_object_init(void *addr, struct debug_obj_descr *descr, int onstack) break; case ODEBUG_STATE_ACTIVE: - debug_print_object(obj, "init"); state = obj->state; raw_spin_unlock_irqrestore(&db->lock, flags); + debug_print_object(obj, "init"); debug_object_fixup(descr->fixup_init, addr, state); return; case ODEBUG_STATE_DESTROYED: + raw_spin_unlock_irqrestore(&db->lock, flags); debug_print_object(obj, "init"); - break; + return; default: break; } raw_spin_unlock_irqrestore(&db->lock, flags); + if (check_stack) + debug_object_is_on_stack(addr, onstack); } /** @@ -473,6 +633,8 @@ int debug_object_activate(void *addr, struct debug_obj_descr *descr) obj = lookup_object(addr, db); if (obj) { + bool print_object = false; + switch (obj->state) { case ODEBUG_STATE_INIT: case ODEBUG_STATE_INACTIVE: @@ -481,14 +643,14 @@ int debug_object_activate(void *addr, struct debug_obj_descr *descr) break; case ODEBUG_STATE_ACTIVE: - debug_print_object(obj, "activate"); state = obj->state; raw_spin_unlock_irqrestore(&db->lock, flags); + debug_print_object(obj, "activate"); ret = debug_object_fixup(descr->fixup_activate, addr, state); return ret ? 0 : -EINVAL; case ODEBUG_STATE_DESTROYED: - debug_print_object(obj, "activate"); + print_object = true; ret = -EINVAL; break; default: @@ -496,10 +658,13 @@ int debug_object_activate(void *addr, struct debug_obj_descr *descr) break; } raw_spin_unlock_irqrestore(&db->lock, flags); + if (print_object) + debug_print_object(obj, "activate"); return ret; } raw_spin_unlock_irqrestore(&db->lock, flags); + /* * We are here when a static object is activated. We * let the type specific code confirm whether this is @@ -531,6 +696,7 @@ void debug_object_deactivate(void *addr, struct debug_obj_descr *descr) struct debug_bucket *db; struct debug_obj *obj; unsigned long flags; + bool print_object = false; if (!debug_objects_enabled) return; @@ -548,24 +714,27 @@ void debug_object_deactivate(void *addr, struct debug_obj_descr *descr) if (!obj->astate) obj->state = ODEBUG_STATE_INACTIVE; else - debug_print_object(obj, "deactivate"); + print_object = true; break; case ODEBUG_STATE_DESTROYED: - debug_print_object(obj, "deactivate"); + print_object = true; break; default: break; } - } else { + } + + raw_spin_unlock_irqrestore(&db->lock, flags); + if (!obj) { struct debug_obj o = { .object = addr, .state = ODEBUG_STATE_NOTAVAILABLE, .descr = descr }; debug_print_object(&o, "deactivate"); + } else if (print_object) { + debug_print_object(obj, "deactivate"); } - - raw_spin_unlock_irqrestore(&db->lock, flags); } EXPORT_SYMBOL_GPL(debug_object_deactivate); @@ -580,6 +749,7 @@ void debug_object_destroy(void *addr, struct debug_obj_descr *descr) struct debug_bucket *db; struct debug_obj *obj; unsigned long flags; + bool print_object = false; if (!debug_objects_enabled) return; @@ -599,20 +769,22 @@ void debug_object_destroy(void *addr, struct debug_obj_descr *descr) obj->state = ODEBUG_STATE_DESTROYED; break; case ODEBUG_STATE_ACTIVE: - debug_print_object(obj, "destroy"); state = obj->state; raw_spin_unlock_irqrestore(&db->lock, flags); + debug_print_object(obj, "destroy"); debug_object_fixup(descr->fixup_destroy, addr, state); return; case ODEBUG_STATE_DESTROYED: - debug_print_object(obj, "destroy"); + print_object = true; break; default: break; } out_unlock: raw_spin_unlock_irqrestore(&db->lock, flags); + if (print_object) + debug_print_object(obj, "destroy"); } EXPORT_SYMBOL_GPL(debug_object_destroy); @@ -641,9 +813,9 @@ void debug_object_free(void *addr, struct debug_obj_descr *descr) switch (obj->state) { case ODEBUG_STATE_ACTIVE: - debug_print_object(obj, "free"); state = obj->state; raw_spin_unlock_irqrestore(&db->lock, flags); + debug_print_object(obj, "free"); debug_object_fixup(descr->fixup_free, addr, state); return; default: @@ -716,6 +888,7 @@ debug_object_active_state(void *addr, struct debug_obj_descr *descr, struct debug_bucket *db; struct debug_obj *obj; unsigned long flags; + bool print_object = false; if (!debug_objects_enabled) return; @@ -731,22 +904,25 @@ debug_object_active_state(void *addr, struct debug_obj_descr *descr, if (obj->astate == expect) obj->astate = next; else - debug_print_object(obj, "active_state"); + print_object = true; break; default: - debug_print_object(obj, "active_state"); + print_object = true; break; } - } else { + } + + raw_spin_unlock_irqrestore(&db->lock, flags); + if (!obj) { struct debug_obj o = { .object = addr, .state = ODEBUG_STATE_NOTAVAILABLE, .descr = descr }; debug_print_object(&o, "active_state"); + } else if (print_object) { + debug_print_object(obj, "active_state"); } - - raw_spin_unlock_irqrestore(&db->lock, flags); } EXPORT_SYMBOL_GPL(debug_object_active_state); @@ -760,7 +936,6 @@ static void __debug_check_no_obj_freed(const void *address, unsigned long size) struct hlist_node *tmp; struct debug_obj *obj; int cnt, objs_checked = 0; - bool work = false; saddr = (unsigned long) address; eaddr = saddr + size; @@ -782,16 +957,16 @@ repeat: switch (obj->state) { case ODEBUG_STATE_ACTIVE: - debug_print_object(obj, "free"); descr = obj->descr; state = obj->state; raw_spin_unlock_irqrestore(&db->lock, flags); + debug_print_object(obj, "free"); debug_object_fixup(descr->fixup_free, (void *) oaddr, state); goto repeat; default: hlist_del(&obj->node); - work |= __free_object(obj); + __free_object(obj); break; } } @@ -807,8 +982,10 @@ repeat: debug_objects_maxchecked = objs_checked; /* Schedule work to actually kmem_cache_free() objects */ - if (work) - schedule_work(&debug_obj_work); + if (!obj_freeing && obj_nr_tofree) { + WRITE_ONCE(obj_freeing, true); + schedule_delayed_work(&debug_obj_work, ODEBUG_FREE_WORK_DELAY); + } } void debug_check_no_obj_freed(const void *address, unsigned long size) @@ -822,13 +999,19 @@ void debug_check_no_obj_freed(const void *address, unsigned long size) static int debug_stats_show(struct seq_file *m, void *v) { + int cpu, obj_percpu_free = 0; + + for_each_possible_cpu(cpu) + obj_percpu_free += per_cpu(percpu_obj_pool.obj_free, cpu); + seq_printf(m, "max_chain :%d\n", debug_objects_maxchain); seq_printf(m, "max_checked :%d\n", debug_objects_maxchecked); seq_printf(m, "warnings :%d\n", debug_objects_warnings); seq_printf(m, "fixups :%d\n", debug_objects_fixups); - seq_printf(m, "pool_free :%d\n", obj_pool_free); + seq_printf(m, "pool_free :%d\n", obj_pool_free + obj_percpu_free); + seq_printf(m, "pool_pcp_free :%d\n", obj_percpu_free); seq_printf(m, "pool_min_free :%d\n", obj_pool_min_free); - seq_printf(m, "pool_used :%d\n", obj_pool_used); + seq_printf(m, "pool_used :%d\n", obj_pool_used - obj_percpu_free); seq_printf(m, "pool_max_used :%d\n", obj_pool_max_used); seq_printf(m, "on_free_list :%d\n", obj_nr_tofree); seq_printf(m, "objs_allocated:%d\n", debug_objects_allocated); @@ -850,26 +1033,16 @@ static const struct file_operations debug_stats_fops = { static int __init debug_objects_init_debugfs(void) { - struct dentry *dbgdir, *dbgstats; + struct dentry *dbgdir; if (!debug_objects_enabled) return 0; dbgdir = debugfs_create_dir("debug_objects", NULL); - if (!dbgdir) - return -ENOMEM; - dbgstats = debugfs_create_file("stats", 0444, dbgdir, NULL, - &debug_stats_fops); - if (!dbgstats) - goto err; + debugfs_create_file("stats", 0444, dbgdir, NULL, &debug_stats_fops); return 0; - -err: - debugfs_remove(dbgdir); - - return -ENOMEM; } __initcall(debug_objects_init_debugfs); @@ -1175,9 +1348,20 @@ free: */ void __init debug_objects_mem_init(void) { + int cpu, extras; + if (!debug_objects_enabled) return; + /* + * Initialize the percpu object pools + * + * Initialization is not strictly necessary, but was done for + * completeness. + */ + for_each_possible_cpu(cpu) + INIT_HLIST_HEAD(&per_cpu(percpu_obj_pool.free_objs, cpu)); + obj_cache = kmem_cache_create("debug_objects_cache", sizeof (struct debug_obj), 0, SLAB_DEBUG_OBJECTS | SLAB_NOLEAKTRACE, @@ -1194,6 +1378,7 @@ void __init debug_objects_mem_init(void) * Increase the thresholds for allocating and freeing objects * according to the number of possible CPUs available in the system. */ - debug_objects_pool_size += num_possible_cpus() * 32; - debug_objects_pool_min_level += num_possible_cpus() * 4; + extras = num_possible_cpus() * ODEBUG_BATCH_SIZE; + debug_objects_pool_size += extras; + debug_objects_pool_min_level += extras; } |