On Sun, Sep 03, 2006 at 01:26:59AM +0000, Dave Jones wrote:
> Seen during boot of a 2.6.18rc5-git1 based kernel.
>
> =======================================================
> [ INFO: possible circular locking dependency detected ]
> 2.6.17-1.2608.fc6 #1
> -------------------------------------------------------
> swapper/0 is trying to acquire lock:
> (&tbl->lock){-+-+}, at: [<c05bdf97>] neigh_lookup+0x50/0xaf
>
> but task is already holding lock:
> (&list->lock#3){-+..}, at: [<c05bf677>] neigh_proxy_process+0x20/0xc2
Looks like a validator bug. Arjan, it seems that the removal of the
lockdep_set_class from skb_queue_head_init doesn't completely cure
the problem.
> the existing dependency chain (in reverse order) is:
>
> -> #2 (&list->lock#3){-+..}:
> [<c043c09a>] lock_acquire+0x4b/0x6d
> [<c061411f>] _spin_lock_irqsave+0x22/0x32
> [<c05b451f>] skb_dequeue+0x12/0x43
> [<c05b523a>] skb_queue_purge+0x14/0x1b
> [<c05be990>] neigh_update+0x34a/0x3a6
This list->lock is n->arp_queue.
> [<c05f0f6e>] arp_process+0x4ad/0x4e7
> [<c05f107c>] arp_rcv+0xd4/0xf1
> [<c05b942c>] netif_receive_skb+0x205/0x274
> [<c7bb0566>] rhine_napipoll+0x28d/0x449 [via_rhine]
> [<c05baf73>] net_rx_action+0x9d/0x196
> [<c04293a7>] __do_softirq+0x78/0xf2
> [<c0406673>] do_softirq+0x5a/0xbe
...
> -> #0 (&tbl->lock){-+-+}:
> [<c043c09a>] lock_acquire+0x4b/0x6d
> [<c0613f02>] _read_lock_bh+0x1e/0x2d
> [<c05bdf97>] neigh_lookup+0x50/0xaf
> [<c05bf0b9>] neigh_event_ns+0x2c/0x77
> [<c05f0e2a>] arp_process+0x369/0x4e7
> [<c05f10a1>] parp_redo+0x8/0xa
> [<c05bf6bd>] neigh_proxy_process+0x66/0xc2
This list->lock is tbl->proxy_queue.
> [<c042dc58>] run_timer_softirq+0x108/0x167
> [<c04293a7>] __do_softirq+0x78/0xf2
> [<c0406673>] do_softirq+0x5a/0xbe
BTW, out of the last four validator reports I've read three have turned
out to be genuine bugs. So you guys have done a fantastic job!
Cheers,
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