On Wed, 2011-07-20 at 16:21 +0300, Pekka Enberg wrote:
> On Sat, 16 Jul 2011, Sebastian Siewior wrote:
> >> 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:
> > 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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