From 50db04dd9c74178e68a981a7127c37252ffb3242 Mon Sep 17 00:00:00 2001 From: Vegard Nossum Date: Sun, 15 Jun 2008 00:47:36 +0200 Subject: debugobjects: fix lockdep warning Daniel J Blueman reported: | ======================================================= | [ INFO: possible circular locking dependency detected ] | 2.6.26-rc5-201c #1 | ------------------------------------------------------- | nscd/3669 is trying to acquire lock: | (&n->list_lock){.+..}, at: [] deactivate_slab+0x173/0x1e0 | | but task is already holding lock: | (&obj_hash[i].lock){++..}, at: [] | __debug_object_init+0x2f/0x350 | | which lock already depends on the new lock. There are two locks involved here; the first is a SLUB-local lock, and the second is a debugobjects-local lock. They are basically taken in two different orders: 1. SLUB { debugobjects { ... } } 2. debugobjects { SLUB { ... } } This patch changes pattern #2 by trying to fill the memory pool (e.g. the call into SLUB/kmalloc()) outside the debugobjects lock, so now the two patterns look like this: 1. SLUB { debugobjects { ... } } 2. SLUB { } debugobjects { ... } [ daniel.blueman@gmail.com: pool_lock needs to be taken irq safe in fill_pool ] Reported-by: Daniel J Blueman Signed-off-by: Vegard Nossum Signed-off-by: Thomas Gleixner --- lib/debugobjects.c | 15 ++++++--------- 1 file changed, 6 insertions(+), 9 deletions(-) (limited to 'lib/debugobjects.c') diff --git a/lib/debugobjects.c b/lib/debugobjects.c index a76a5e122ae1..85b18d79be89 100644 --- a/lib/debugobjects.c +++ b/lib/debugobjects.c @@ -68,6 +68,7 @@ static int fill_pool(void) { gfp_t gfp = GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN; struct debug_obj *new; + unsigned long flags; if (likely(obj_pool_free >= ODEBUG_POOL_MIN_LEVEL)) return obj_pool_free; @@ -81,10 +82,10 @@ static int fill_pool(void) if (!new) return obj_pool_free; - spin_lock(&pool_lock); + spin_lock_irqsave(&pool_lock, flags); hlist_add_head(&new->node, &obj_pool); obj_pool_free++; - spin_unlock(&pool_lock); + spin_unlock_irqrestore(&pool_lock, flags); } return obj_pool_free; } @@ -110,16 +111,13 @@ static struct debug_obj *lookup_object(void *addr, struct debug_bucket *b) } /* - * Allocate a new object. If the pool is empty and no refill possible, - * switch off the debugger. + * Allocate a new object. If the pool is empty, switch off the debugger. */ static struct debug_obj * alloc_object(void *addr, struct debug_bucket *b, struct debug_obj_descr *descr) { struct debug_obj *obj = NULL; - int retry = 0; -repeat: spin_lock(&pool_lock); if (obj_pool.first) { obj = hlist_entry(obj_pool.first, typeof(*obj), node); @@ -141,9 +139,6 @@ repeat: } spin_unlock(&pool_lock); - if (fill_pool() && !obj && !retry++) - goto repeat; - return obj; } @@ -261,6 +256,8 @@ __debug_object_init(void *addr, struct debug_obj_descr *descr, int onstack) struct debug_obj *obj; unsigned long flags; + fill_pool(); + db = get_bucket((unsigned long) addr); spin_lock_irqsave(&db->lock, flags); -- cgit v1.2.3 From 8b05c7e6e159d2f33c9275281b8b909a89eb7c5d Mon Sep 17 00:00:00 2001 From: FUJITA Tomonori Date: Wed, 23 Jul 2008 21:26:53 -0700 Subject: add a helper function to test if an object is on the stack lib/debugobjects.c has a function to test if an object is on the stack. The block layer and ide needs it (they need to avoid DMA from/to stack buffers). This patch moves the function to include/linux/sched.h so that everyone can use it. lib/debugobjects.c uses current->stack but this patch uses a task_stack_page() accessor, which is a preferable way to access the stack. Signed-off-by: FUJITA Tomonori Cc: Christoph Lameter Cc: Andy Whitcroft Cc: Ingo Molnar Cc: Thomas Gleixner Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/debugobjects.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) (limited to 'lib/debugobjects.c') diff --git a/lib/debugobjects.c b/lib/debugobjects.c index 85b18d79be89..f86196390cfd 100644 --- a/lib/debugobjects.c +++ b/lib/debugobjects.c @@ -226,15 +226,13 @@ debug_object_fixup(int (*fixup)(void *addr, enum debug_obj_state state), static void debug_object_is_on_stack(void *addr, int onstack) { - void *stack = current->stack; int is_on_stack; static int limit; if (limit > 4) return; - is_on_stack = (addr >= stack && addr < (stack + THREAD_SIZE)); - + is_on_stack = object_is_on_stack(addr); if (is_on_stack == onstack) return; -- cgit v1.2.3 From 5cd2b459d326a424671dcd95f038649f7bf7cb96 Mon Sep 17 00:00:00 2001 From: Arjan van de Ven Date: Fri, 25 Jul 2008 19:45:39 -0700 Subject: Use WARN() in lib/ Use WARN() instead of a printk+WARN_ON() pair; this way the message becomes part of the warning section for better reporting/collection. In addition, one of the if() clauses collapes into the WARN() entirely now. Signed-off-by: Arjan van de Ven Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/debugobjects.c | 15 +++++---------- 1 file changed, 5 insertions(+), 10 deletions(-) (limited to 'lib/debugobjects.c') diff --git a/lib/debugobjects.c b/lib/debugobjects.c index f86196390cfd..45a6bde762d1 100644 --- a/lib/debugobjects.c +++ b/lib/debugobjects.c @@ -205,9 +205,8 @@ static void debug_print_object(struct debug_obj *obj, char *msg) if (limit < 5 && obj->descr != descr_test) { limit++; - printk(KERN_ERR "ODEBUG: %s %s object type: %s\n", msg, + WARN(1, KERN_ERR "ODEBUG: %s %s object type: %s\n", msg, obj_states[obj->state], obj->descr->name); - WARN_ON(1); } debug_objects_warnings++; } @@ -733,26 +732,22 @@ check_results(void *addr, enum debug_obj_state state, int fixups, int warnings) obj = lookup_object(addr, db); if (!obj && state != ODEBUG_STATE_NONE) { - printk(KERN_ERR "ODEBUG: selftest object not found\n"); - WARN_ON(1); + WARN(1, KERN_ERR "ODEBUG: selftest object not found\n"); goto out; } if (obj && obj->state != state) { - printk(KERN_ERR "ODEBUG: selftest wrong state: %d != %d\n", + WARN(1, KERN_ERR "ODEBUG: selftest wrong state: %d != %d\n", obj->state, state); - WARN_ON(1); goto out; } if (fixups != debug_objects_fixups) { - printk(KERN_ERR "ODEBUG: selftest fixups failed %d != %d\n", + WARN(1, KERN_ERR "ODEBUG: selftest fixups failed %d != %d\n", fixups, debug_objects_fixups); - WARN_ON(1); goto out; } if (warnings != debug_objects_warnings) { - printk(KERN_ERR "ODEBUG: selftest warnings failed %d != %d\n", + WARN(1, KERN_ERR "ODEBUG: selftest warnings failed %d != %d\n", warnings, debug_objects_warnings); - WARN_ON(1); goto out; } res = 0; -- cgit v1.2.3 From 673d62cc5ea6fca046650f17f77985b112c62322 Mon Sep 17 00:00:00 2001 From: Vegard Nossum Date: Sun, 31 Aug 2008 23:39:21 +0200 Subject: debugobjects: fix lockdep warning Daniel J. Blueman reported: > ======================================================= > [ INFO: possible circular locking dependency detected ] > 2.6.27-rc4-224c #1 > ------------------------------------------------------- > hald/4680 is trying to acquire lock: > (&n->list_lock){++..}, at: [] add_partial+0x26/0x80 > > but task is already holding lock: > (&obj_hash[i].lock){++..}, at: [] > debug_object_free+0x5c/0x120 We fix it by moving the actual freeing to outside the lock (the lock now only protects the list). The pool lock is also promoted to irq-safe (suggested by Dan). It's necessary because free_pool is now called outside the irq disabled region. So we need to protect against an interrupt handler which calls debug_object_init(). [tglx@linutronix.de: added hlist_move_list helper to avoid looping through the list twice] Reported-by: Daniel J Blueman Signed-off-by: Vegard Nossum Signed-off-by: Thomas Gleixner --- lib/debugobjects.c | 31 +++++++++++++++++++++++-------- 1 file changed, 23 insertions(+), 8 deletions(-) (limited to 'lib/debugobjects.c') diff --git a/lib/debugobjects.c b/lib/debugobjects.c index 45a6bde762d1..e3ab374e1334 100644 --- a/lib/debugobjects.c +++ b/lib/debugobjects.c @@ -112,6 +112,7 @@ static struct debug_obj *lookup_object(void *addr, struct debug_bucket *b) /* * 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) @@ -148,17 +149,18 @@ alloc_object(void *addr, struct debug_bucket *b, struct debug_obj_descr *descr) static void free_object(struct debug_obj *obj) { unsigned long idx = (unsigned long)(obj - obj_static_pool); + unsigned long flags; if (obj_pool_free < ODEBUG_POOL_SIZE || idx < ODEBUG_POOL_SIZE) { - spin_lock(&pool_lock); + spin_lock_irqsave(&pool_lock, flags); hlist_add_head(&obj->node, &obj_pool); obj_pool_free++; obj_pool_used--; - spin_unlock(&pool_lock); + spin_unlock_irqrestore(&pool_lock, flags); } else { - spin_lock(&pool_lock); + spin_lock_irqsave(&pool_lock, flags); obj_pool_used--; - spin_unlock(&pool_lock); + spin_unlock_irqrestore(&pool_lock, flags); kmem_cache_free(obj_cache, obj); } } @@ -171,6 +173,7 @@ static void debug_objects_oom(void) { struct debug_bucket *db = obj_hash; struct hlist_node *node, *tmp; + HLIST_HEAD(freelist); struct debug_obj *obj; unsigned long flags; int i; @@ -179,11 +182,14 @@ static void debug_objects_oom(void) for (i = 0; i < ODEBUG_HASH_SIZE; i++, db++) { spin_lock_irqsave(&db->lock, flags); - hlist_for_each_entry_safe(obj, node, tmp, &db->list, node) { + hlist_move_list(&db->list, &freelist); + spin_unlock_irqrestore(&db->lock, flags); + + /* Now free them */ + hlist_for_each_entry_safe(obj, node, tmp, &freelist, node) { hlist_del(&obj->node); free_object(obj); } - spin_unlock_irqrestore(&db->lock, flags); } } @@ -498,8 +504,9 @@ void debug_object_free(void *addr, struct debug_obj_descr *descr) return; default: hlist_del(&obj->node); + spin_unlock_irqrestore(&db->lock, flags); free_object(obj); - break; + return; } out_unlock: spin_unlock_irqrestore(&db->lock, flags); @@ -510,6 +517,7 @@ static void __debug_check_no_obj_freed(const void *address, unsigned long size) { unsigned long flags, oaddr, saddr, eaddr, paddr, chunks; struct hlist_node *node, *tmp; + HLIST_HEAD(freelist); struct debug_obj_descr *descr; enum debug_obj_state state; struct debug_bucket *db; @@ -545,11 +553,18 @@ repeat: goto repeat; default: hlist_del(&obj->node); - free_object(obj); + hlist_add_head(&obj->node, &freelist); break; } } spin_unlock_irqrestore(&db->lock, flags); + + /* Now free them */ + hlist_for_each_entry_safe(obj, node, tmp, &freelist, node) { + hlist_del(&obj->node); + free_object(obj); + } + if (cnt > debug_objects_maxchain) debug_objects_maxchain = cnt; } -- cgit v1.2.3