On Wed, 2011-07-20 at 16:21 +0300, Pekka Enberg wrote:

On Sat, 16 Jul 2011, Sebastian Siewior wrote:

quoted

quoted

just hit the following with full debuging turned on:

| =============================================
| [ INFO: possible recursive locking detected ]
| 3.0.0-rc7-00088-g1765a36 #64
| ---------------------------------------------
| udevd/1054 is trying to acquire lock:
|  (&(&parent->list_lock)->rlock){..-...}, at: [<c00bf640>] cache_alloc_refill+0xac/0x868
|
| but task is already holding lock:
|  (&(&parent->list_lock)->rlock){..-...}, at: [<c00be47c>] cache_flusharray+0x58/0x148
|
| other info that might help us debug this:
|  Possible unsafe locking scenario:
|
|        CPU0
|        ----
|   lock(&(&parent->list_lock)->rlock);
|   lock(&(&parent->list_lock)->rlock);

On Sun, 17 Jul 2011, Thomas Gleixner wrote:

quoted

Known problem. Pekka is looking into it.

Actually, I kinda was hoping Peter would make it go away. ;-)

Looking at the lockdep report, it's l3->list_lock and I really don't quite 
understand why it started to happen now. There hasn't been any major 
changes in mm/slab.c for a while. Did lockdep become more strict recently?

Not that I know.. :-) I bet -rt just makes it easier to trigger this
weirdness.

Let me try and look at slab.c without my eyes burning out.. I so hate
that code.

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