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Subject: Re: BUG on 3.0-rc on commit
 d72bce0e67e8afc6eb959f656013cbb577426f1e
From: Peter Zijlstra <peterz@infradead.org>
To: habanero@linux.vnet.ibm.com
Cc: linux-kernel@vger.kernel.org, rostedt <rostedt@goodmis.org>,
        paulmck <paulmck@linux.vnet.ibm.com>
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Date: Fri, 10 Jun 2011 16:11:24 +0200
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On Fri, 2011-06-10 at 08:17 -0500, Andrew Theurer wrote:
> Looks like commit d72bce0e67e8afc6eb959f656013cbb577426f1e breaks my
> boot:
> 
> BUG: unable to handle kernel NULL pointer dereference at
> 0000000000000004
> IP: [<ffffffff8104e8b1>] find_lowest_rq+0xa1/0x150
> PGD 0
> Oops: 0000 [#1] SMP
> CPU 0
> Modules linked in:
> 
> Pid: 1, comm: swapper Not tainted 3.0.0-rc1-00001-gd72bce0 #32 IBM
> -[7145AC1]-/Node 1, Processor Card
> RIP: 0010:[<ffffffff8104e8b1>]  [<ffffffff8104e8b1>] find_lowest_rq
> +0xa1/0x150
> RSP: 0018:ffff883732925ca0  EFLAGS: 00010002
> RAX: 0000000000000020 RBX: 0000000000000020 RCX: 0000000000000050
> RDX: 00000000ffffffff RSI: 0000000000000050 RDI: 0000000000000050
> RBP: ffff883732925cd0 R08: ffff883732774d38 R09: 0000000000000000
> R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000012ac0
> FS:  0000000000000000(0000) GS:ffff88387f800000(0000)
> knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
> CR2: 0000000000000004 CR3: 0000000001a03000 CR4: 00000000000006f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> Process swapper (pid: 1, threadinfo ffff883732924000, task
> ffff8837329234c0)
> Stack:
>  ffff883732925cf0 0000000000000020 0000000000000020 ffff883732775300
>  0000000000000000 0000000000000286 ffff883732925cf0 ffffffff8104e9da
>  0000000000000022 ffff883732774b40 ffff883732925d40 ffffffff8105ae11
> Call Trace:
>  [<ffffffff8104e9da>] select_task_rq_rt+0x7a/0x90
>  [<ffffffff8105ae11>] try_to_wake_up+0x111/0x280
>  [<ffffffff8105afd5>] wake_up_process+0x15/0x20
>  [<ffffffff814cc5c9>] rcu_cpu_notify+0xd6/0x196
>  [<ffffffff814d6625>] notifier_call_chain+0x55/0x80
>  [<ffffffff8108a77e>] __raw_notifier_call_chain+0xe/0x10
>  [<ffffffff81064560>] __cpu_notify+0x20/0x40
>  [<ffffffff814caf88>] _cpu_up+0xc7/0x10e
>  [<ffffffff814cb0a6>] cpu_up+0xd7/0xea
>  [<ffffffff81c41cab>] smp_init+0x41/0x96
>  [<ffffffff81c227d4>] kernel_init+0x1d6/0x262
>  [<ffffffff814dbc04>] kernel_thread_helper+0x4/0x10
>  [<ffffffff81c225fe>] ? do_basic_setup+0x5c/0x5c
>  [<ffffffff814dbc00>] ? gs_change+0x13/0x13
> Code: 2a 01 00 48 89 fe 48 8b 04 c5 40 a3 bf 81 4c 89 e2 49 8b 84 07 88
> 08 00 00 48 83 c0 38 48 89 c7 e8 b5 74 0a 00 85 c0 74 ae 89 d8
>  0f a3 1c 24 19 d2 85 d2 75 a6 45 0f a3 2c 24 19 c0 41 be ff
> RIP  [<ffffffff8104e8b1>] find_lowest_rq+0xa1/0x150
>  RSP <ffff883732925ca0>
> CR2: 0000000000000004
> ---[ end trace 6afdf060c90559fd ]---

> 
> This is on a Westmere-EX (4 socket, 40 cores)

Hmm, how often does that happen? my wsm-ep (2*6*2) doesn't seem to
suffer said problem. I'll try and see if I can spot the boo-boo. Also,
happen to have a .config handy?
--
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