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author | Vegard Nossum <vegard.nossum@gmail.com> | 2008-06-15 00:47:36 +0200 |
---|---|---|
committer | Thomas Gleixner <tglx@linutronix.de> | 2008-06-18 11:09:54 +0200 |
commit | 50db04dd9c74178e68a981a7127c37252ffb3242 (patch) | |
tree | ac961b1ccc6f5073537be2b4b731bc79ec5448c4 /lib | |
parent | 952f4a0a9b27e6dbd5d32e330b3f609ebfa0b061 (diff) | |
download | linux-3.10-50db04dd9c74178e68a981a7127c37252ffb3242.tar.gz linux-3.10-50db04dd9c74178e68a981a7127c37252ffb3242.tar.bz2 linux-3.10-50db04dd9c74178e68a981a7127c37252ffb3242.zip |
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: [<ffffffff802bab03>] deactivate_slab+0x173/0x1e0
|
| but task is already holding lock:
| (&obj_hash[i].lock){++..}, at: [<ffffffff803fa56f>]
| __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 <daniel.blueman@gmail.com>
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'lib')
-rw-r--r-- | lib/debugobjects.c | 15 |
1 files changed, 6 insertions, 9 deletions
diff --git a/lib/debugobjects.c b/lib/debugobjects.c index a76a5e122ae..85b18d79be8 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); |