The patch titled
debugobjects: fix lockdep warning
has been added to the -mm tree. Its filename is
debugobjects-fix-lockdep-warning.patch
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*** 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
--
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