From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vegard Nossum Subject: [PATCH] debugobjects: fix lockdep warning #2 Date: Thu, 28 Aug 2008 17:32:14 +0200 Message-ID: <20080828153214.GA27653@localhost.localdomain> Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:date:to:cc:subject:message-id :mime-version:content-type:content-disposition:user-agent:from; bh=q/bWYfNUtvpCXN8w+Yetvnv0MV5wA/do9ZKWnqQNzXA=; b=oOCZQuYjW0Lh9KhK+3KplZ20bXIsqRkcJ4QhO4mxzJMs1G0uc8nOqRqU1Y+ss+WutV J/ZbBLPykcEoGheZe0SLtKddQ/97uF768GmcIy+Hkvbz7SscEDzHIgXw4et/Cg0SqwMg bUr/dUYadcOhP/R2/QHOFyng+zEanDSksbFQU= Content-Disposition: inline Sender: kernel-testers-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Ingo Molnar Cc: Daniel J Blueman , Thomas Gleixner , Christoph Lameter , Linus Torvalds , "Rafael J. Wysocki" , Linux Kernel Mailing List , Adrian Bunk , Andrew Morton , Natalie Protasevich , Kernel Testers List On Thu, Aug 28, 2008 at 3:56 PM, Ingo Molnar wrote: > could you resend the final patch please? It's a candidate for .27, if it > works out fine. Here is the combined patch. I've tested it only briefly, and I am unsure of whether it still produces lockdep warnings for Daniel or not. I wish it would not be applied anywhere unless it was officially Reviewed-by: someone. In particular, I'm not quite steady with the irq-safe locking (Thomas might want to have a look). Thanks :) Vegard >From 977cf583b79be7308d5e310711fe6038c8af96a4 Mon Sep 17 00:00:00 2001 From: Vegard Nossum Date: Thu, 28 Aug 2008 17:09:57 +0200 Subject: [PATCH] debugobjects: fix lockdep warning #2 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 lock is also promoted to irq-safe (suggested by Dan). Reported-by: Daniel J Blueman Signed-off-by: Vegard Nossum --- lib/debugobjects.c | 38 +++++++++++++++++++++++++++++--------- 1 files changed, 29 insertions(+), 9 deletions(-) diff --git a/lib/debugobjects.c b/lib/debugobjects.c index 19acf8c..acf9ed8 100644 --- a/lib/debugobjects.c +++ b/lib/debugobjects.c @@ -115,9 +115,10 @@ static struct debug_obj *lookup_object(void *addr, struct debug_bucket *b) static struct debug_obj * alloc_object(void *addr, struct debug_bucket *b, struct debug_obj_descr *descr) { + unsigned long flags; struct debug_obj *obj = NULL; - spin_lock(&pool_lock); + spin_lock_irqsave(&pool_lock, flags); if (obj_pool.first) { obj = hlist_entry(obj_pool.first, typeof(*obj), node); @@ -136,7 +137,7 @@ alloc_object(void *addr, struct debug_bucket *b, struct debug_obj_descr *descr) if (obj_pool_free < obj_pool_min_free) obj_pool_min_free = obj_pool_free; } - spin_unlock(&pool_lock); + spin_unlock_irqrestore(&pool_lock, flags); return obj; } @@ -146,18 +147,19 @@ alloc_object(void *addr, struct debug_bucket *b, struct debug_obj_descr *descr) */ static void free_object(struct debug_obj *obj) { + unsigned long flags; unsigned long idx = (unsigned long)(obj - obj_static_pool); 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); } } @@ -170,19 +172,28 @@ 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; printk(KERN_WARNING "ODEBUG: Out of memory. ODEBUG disabled\n"); + /* XXX: Could probably be optimized by transplantation of more than + * one entry at a time. */ 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_del(&obj->node); - free_object(obj); + hlist_add_head(&obj->node, &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); + } } } @@ -500,8 +511,9 @@ 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); @@ -512,6 +524,7 @@ 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; @@ -547,11 +560,18 @@ 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; } -- 1.5.5.1