The patch titled debugobjects: fix lockdep warning has been added to the -mm tree. Its filename is debugobjects-fix-lockdep-warning.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: debugobjects: fix lockdep warning From: Vegard Nossum <vegard.nossum@xxxxxxxxx> 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: [<ffffffff802bfa26>] add_partial+0x26/0x80 > > but task is already holding lock: > (&obj_hash[i].lock){++..}, at: [<ffffffff8041cfdc>] > 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 <daniel.blueman@xxxxxxxxx> Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Cc: "Rafael J. Wysocki" <rjw@xxxxxxx> Cc: Ingo Molnar <mingo@xxxxxxx> Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- lib/debugobjects.c | 38 +++++++++++++++++++++++++++++--------- 1 file changed, 29 insertions(+), 9 deletions(-) diff -puN lib/debugobjects.c~debugobjects-fix-lockdep-warning lib/debugobjects.c --- a/lib/debugobjects.c~debugobjects-fix-lockdep-warning +++ a/lib/debugobjects.c @@ -116,9 +116,10 @@ static struct debug_obj *lookup_object(v 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); @@ -137,7 +138,7 @@ alloc_object(void *addr, struct debug_bu 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; } @@ -147,18 +148,19 @@ alloc_object(void *addr, struct debug_bu */ 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); } } @@ -171,19 +173,28 @@ 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); + } } } @@ -498,8 +509,9 @@ void debug_object_free(void *addr, struc 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 +522,7 @@ static void __debug_check_no_obj_freed(c { 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 +558,18 @@ 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; } _ Patches currently in -mm which might be from vegard.nossum@xxxxxxxxx are origin.patch linux-next.patch debugobjects-fix-lockdep-warning.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html