3.0.4 + rt12: deadlock

[Fernando Lopez-Lezcano <nando@ccrma.Stanford.EDU>]

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Booting 3.0.4 + rt12 on a quadcore workstation (running fc14) gave me this:

----
=============================================
[ INFO: possible recursive locking detected ]
3.0.4-1.rt12.1.fc14.ccrma.i686.rtPAE #1
---------------------------------------------
swapper/0 is trying to acquire lock:
  (&parent->list_lock){+.+...}, at: [<c05054ce>] 
__cache_free.clone.27+0x45/0xc4

but task is already holding lock:
  (&parent->list_lock){+.+...}, at: [<c050662c>] do_tune_cpucache+0xf0/0x2b0

other info that might help us debug this:
  Possible unsafe locking scenario:

        CPU0
        ----
   lock(&parent->list_lock);
   lock(&parent->list_lock);

  *** DEADLOCK ***

  May be due to missing lock nesting notation

3 locks held by swapper/0:
  #0:  (cache_chain_mutex){+.+...}, at: [<c0bedb96>] 
kmem_cache_init_late+0x15/0x61
  #1:  (&per_cpu(slab_lock, __cpu).lock){+.+...}, at: [<c0504a53>] 
__local_lock_irq+0x1e/0x5b
  #2:  (&parent->list_lock){+.+...}, at: [<c050662c>] 
do_tune_cpucache+0xf0/0x2b0

stack backtrace:
Pid: 0, comm: swapper Not tainted 3.0.4-1.rt12.1.fc14.ccrma.i686.rtPAE #1
Call Trace:
  [<c086e6f6>] ? printk+0x2d/0x2f
  [<c0479b36>] __lock_acquire+0x8b3/0xc2f
  [<c086fd96>] ? rt_spin_lock_slowlock+0x67/0x170
  [<c04790ee>] ? mark_lock+0x26/0x1bb
  [<c05054ce>] ? __cache_free.clone.27+0x45/0xc4
  [<c047a372>] lock_acquire+0xde/0x11d
  [<c05054ce>] ? __cache_free.clone.27+0x45/0xc4
  [<c08703b4>] rt_spin_lock+0x3d/0x43
  [<c05054ce>] ? __cache_free.clone.27+0x45/0xc4
  [<c05054ce>] __cache_free.clone.27+0x45/0xc4
  [<c0437c83>] ? test_ti_thread_flag+0x8/0x10
  [<c0505303>] kmem_cache_free+0x73/0xe1
  [<c05053c0>] slab_destroy+0x4f/0x53
  [<c0505458>] free_block+0x94/0xc5
  [<c0506645>] do_tune_cpucache+0x109/0x2b0
  [<c05069c7>] enable_cpucache+0x7b/0xa7
  [<c0bedba7>] kmem_cache_init_late+0x26/0x61
  [<c0bcd68a>] start_kernel+0x24f/0x367
  [<c0bcd1d1>] ? loglevel+0x1a/0x1a
  [<c0bcd13b>] ? reserve_ebda_region+0x70/0x72
  [<c0bcd0c3>] i386_start_kernel+0xb2/0xba
Console: colour VGA+ 80x25
console [tty0] enabled
Lock dependency validator: Copyright (c) 2006 Red Hat, Inc., Ingo Molnar
... MAX_LOCKDEP_SUBCLASSES:  8
... MAX_LOCK_DEPTH:          48
... MAX_LOCKDEP_KEYS:        8191
... CLASSHASH_SIZE:          4096
... MAX_LOCKDEP_ENTRIES:     32768
... MAX_LOCKDEP_CHAINS:      65536
... CHAINHASH_SIZE:          32768
----

I started working and a little while later the machine froze (jack + 
heavy prioritized udp traffic in eth1 - with the r8169 driver). It 
recognized alt-sysrq boot so it was not completely dead. Nothing left on 
the logs to see.

Full config attached.
-- Fernando

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