Hi Andrew,

I was seeing a lockup with several -mm releases since 2.6.12-rc2-mm1
(IIRC). With 2.6.12-rc2-mm1, I remember getting the lockup a few minutes
after boot time.
With 2.6.12-rc3-mm1, I waited several days before getting it.
But, I finally caught this one with netconsole. So here it is:

BUG: soft lockup detected on CPU#0!
Pid: 0, comm:              swapper
EIP: 0060:[<c02d40a5>] CPU: 0
EIP is at _spin_unlock_irqrestore+0x5/0x30
 EFLAGS: 00000286    Not tainted  (2.6.12-rc3-mm1=Pignouf)
EAX: c18e8160 EBX: c18e8160 ECX: 00000001 EDX: 00000286
ESI: c18e0160 EDI: dbf96c64 EBP: ffffffff DS: 007b ES: 007b
CR0: 8005003b CR2: b6e43000 CR3: 0e912000 CR4: 00000690
 [<c012a635>] __mod_timer+0xc5/0xf0
 [<c028105f>] sk_reset_timer+0x1f/0x30
 [<c02bb0e0>] tcp_v4_rcv+0x6a0/0x8d0
 [<c029e2ab>] ip_local_deliver+0xdb/0x260
 [<c029e9c0>] ip_local_deliver_finish+0x0/0x1d0
 [<c029e6bc>] ip_rcv+0x28c/0x590
 [<c02884c8>] netif_receive_skb+0x178/0x240
 [<c0288619>] process_backlog+0x89/0x140
 [<c0288777>] net_rx_action+0xa7/0x1d0
 [<c01263ed>] __do_softirq+0xdd/0x100
 [<c0105b20>] do_softirq+0x70/0x80
 =======================
 [<c0126504>] irq_exit+0x44/0x50
 [<c0103c60>] apic_timer_interrupt+0x1c/0x24
 [<c0101063>] mwait_idle+0x33/0x50
 [<e0237adb>] acpi_processor_idle+0x0/0x2aa [processor]
 [<e0237bdf>] acpi_processor_idle+0x104/0x2aa [processor]
 [<e0237adb>] acpi_processor_idle+0x0/0x2aa [processor]
 [<c0100e51>] cpu_idle+0x61/0x80
 [<c03a99b4>] start_kernel+0x164/0x180
 [<c03a93c0>] unknown_bootoption+0x0/0x1e0

I never saw any lockup with 2.6.11. I don't think I ever tried 2.6.12-rc
releases or previous -mm releases on this box.
I can test some other releases for sure. But, the lockup isn't easy to
reproduce. I can't even be sure that this is the same that occured a few
minutes after booting rc2-mm1.

The box is a Dell Dimension 3000 with a 3GHz P4 with Hyperthreading.
/proc/cpuinfo, lspci and .config are attached.

Brice