Re: BUG on 3.0-rc on commit d72bce0e67e8afc6eb959f656013cbb577426f1e

[Andrew Theurer <habanero@linux.vnet.ibm.com>]

On Fri, 2011-06-10 at 10:34 -0500, Andrew Theurer wrote:
> On Fri, 2011-06-10 at 16:45 +0200, Peter Zijlstra wrote:
> > On Fri, 2011-06-10 at 16:11 +0200, Peter Zijlstra wrote:
> > > 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:
> 
> > > 
> > > > 
> > > > 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?
> > 
> > Does the below cure things?
> 
> I am afraid not:

Forgot to mention, if I boot with maxcpus=1, the online the rest of the
CPUs later, I can avoid the problem.

> 
> Linux version 3.0.0-rc2-00251-g7f45e5c-dirty (root@vg-host.linuxperf9025.net) (gcc version 4.4.5 20110214 (Red Hat 4.4.5-6) (GCC) ) #34 SMP Fri Jun 10 10:23:06 CDT 2011
> Command line: initrd=vg-host/initramfs.img ro root=UUID=7e96e905-9ec4-45ab-abd4-77d1469d6e5a console=tty0 console=ttyS0,115200 rdshell BOOT_IMAGE=vg-host/vmlinuz
> .
> .
> .
> .
> NMI watchdog enabled, takes one hw-pmu counter.
>  #23
> NMI watchdog enabled, takes one hw-pmu counter.
>  #24
> BUG: unable to handle kernel NULL pointer dereference at           (null)
> IP: [<ffffffff8104e8c1>] 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-rc2-00251-g7f45e5c-dirty #34 IBM  -[7145AC1]-/Node 1, Processor Card
> RIP: 0010:[<ffffffff8104e8c1>]  [<ffffffff8104e8c1>] find_lowest_rq+0xa1/0x150
> RSP: 0018:ffff883732925ca0  EFLAGS: 00010002
> RAX: 0000000000000010 RBX: 0000000000000010 RCX: 0000000000000050
> RDX: 00000000ffffffff RSI: 0000000000000050 RDI: 0000000000000050
> RBP: ffff883732925cd0 R08: ffff8837325b4238 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: 0000000000000000 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:
>  ffff883732925cd0 0000000000000010 0000000000000010 ffff8837325b4800
>  0000000000000000 0000000000000286 ffff883732925cf0 ffffffff8104e9ea
>  ffff883732642040 ffff8837325b4040 ffff883732925d40 ffffffff8105ac79
> Call Trace:
>  [<ffffffff8104e9ea>] select_task_rq_rt+0x7a/0x90
>  [<ffffffff8105ac79>] try_to_wake_up+0x119/0x2a0
>  [<ffffffff8105ae55>] wake_up_process+0x15/0x20
>  [<ffffffff814cc59f>] rcu_cpu_notify+0xd6/0x196
>  [<ffffffff814d65e5>] notifier_call_chain+0x55/0x80
>  [<ffffffff8108a7be>] __raw_notifier_call_chain+0xe/0x10
>  [<ffffffff81064590>] __cpu_notify+0x20/0x40
>  [<ffffffff814caf5e>] _cpu_up+0xc7/0x10e
>  [<ffffffff814cb07c>] cpu_up+0xd7/0xea
>  [<ffffffff81c41dfb>] smp_init+0x41/0x96
>  [<ffffffff81c227d4>] kernel_init+0x1d6/0x262
>  [<ffffffff814dbbc4>] kernel_thread_helper+0x4/0x10
>  [<ffffffff81c225fe>] ? do_basic_setup+0x5c/0x5c
>  [<ffffffff814dbbc0>] ? 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 85 75 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  [<ffffffff8104e8c1>] find_lowest_rq+0xa1/0x150
>  RSP <ffff883732925ca0>
> CR2: 0000000000000000
> ---[ end trace 050353be83bb766f ]---
> 
-Andrew