Hi Christoph,

This kernel oops happens on a Nehalem-EX machine and is related to
some commit in the percpu branch(*). I'm not able to bisect it down
because the machine failed to reboot itself on this oops..

(*) head commit is

commit 8d20cc9cfe7f5c466dac63509c8f80db41e31015
Commit:     Christoph Lameter <cl@gentwo.org>
CommitDate: Fri Aug 8 11:11:03 2014 -0500

    One & too much

[    1.473733] x86: Booting SMP configuration:
[    1.478547] .... node  #1, CPUs:        #1
[    1.495060] masked ExtINT on CPU#1
[    1.578419] BUG: unable to handle kernel paging request at 000000000000de40
[    1.586556] IP: [<ffffffff8104c8c9>] __x2apic_send_IPI_mask+0x39/0x190
[    1.594057] PGD 0
[    1.596508] Oops: 0000 [#1] SMP
[    1.600381] Modules linked in:
[    1.603998] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.16.0-00251-g7d674bb #1
[    1.612284] Hardware name: QCI QSSC-S4R/QSSC-S4R, BIOS QSSC-S4R.QCI.01.00.0023.020920102021 02/09/2010
[    1.622901] task: ffff882027ba8000 ti: ffff8810273fc000 task.ti: ffff8810273fc000
[    1.631478] RIP: 0010:[<ffffffff8104c8c9>]  [<ffffffff8104c8c9>] __x2apic_send_IPI_mask+0x39/0x190
[    1.641767] RSP: 0000:ffff8810273ffc48  EFLAGS: 00010096
[    1.647840] RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffffff81d6c4e0
[    1.655954] RDX: 0000000000080000 RSI: 00000000000000fd RDI: ffffffff81848260
[    1.664069] RBP: ffff8810273ffc98 R08: 0000000000000008 R09: 0000000000000000
[    1.672183] R10: ffffffff81848260 R11: ffff8810273ffb5e R12: ffff882027bad880
[    1.680297] R13: ffff88203fc14840 R14: 0000000000000001 R15: 0000000000080000
[    1.688412] FS:  0000000000000000(0000) GS:ffff88103fa00000(0000) knlGS:0000000000000000
[    1.697674] CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[    1.704232] CR2: 000000000000de40 CR3: 0000000001bfd000 CR4: 00000000000007f0
[    1.712347] Stack:
[    1.714725]  0000000000000096 000000fd810ace79 000000ea27ba8068 00000000000000df
[    1.723484]  ffff882027bad8e8 0000000000000001 ffff882027bad880 ffff88203fc14840
[    1.732231]  0000000000000001 ffff88203fc14840 ffff8810273ffca8 ffffffff8104ca93
[    1.740992] Call Trace:
[    1.743861]  [<ffffffff8104ca93>] x2apic_send_IPI_mask+0x13/0x20
[    1.750714]  [<ffffffff8104346a>] native_smp_send_reschedule+0x4a/0x60
[    1.758149]  [<ffffffff8109da08>] resched_task+0xa8/0xd0
[    1.764222]  [<ffffffff8109e685>] check_preempt_curr+0x75/0xa0
[    1.770883]  [<ffffffff8109e6c9>] ttwu_do_wakeup+0x19/0xe0
[    1.777155]  [<ffffffff8109e83d>] ttwu_do_activate.constprop.85+0x5d/0x70
[    1.784876]  [<ffffffff810a14b4>] try_to_wake_up+0x1d4/0x350
[    1.791344]  [<ffffffff810a1680>] wake_up_state+0x10/0x20
[    1.797514]  [<ffffffff810909bd>] __kthread_unpark+0x5d/0x60
[    1.803975]  [<ffffffff81090f4e>] kthread_unpark+0x1e/0x30
[    1.810245]  [<ffffffff81097e2c>] smpboot_unpark_thread.isra.1+0x2c/0x30
[    1.817874]  [<ffffffff8109824f>] smpboot_unpark_threads+0x3f/0x60
[    1.824922]  [<ffffffff8106d45d>] _cpu_up+0x15d/0x180
[    1.830697]  [<ffffffff8106d509>] cpu_up+0x89/0xb0
[    1.836187]  [<ffffffff81db5b71>] smp_init+0x85/0x87
[    1.841871]  [<ffffffff81d9217f>] kernel_init_freeable+0x119/0x22b
[    1.848919]  [<ffffffff81817af0>] ? rest_init+0x90/0x90
[    1.854895]  [<ffffffff81817afe>] kernel_init+0xe/0xf0
[    1.860774]  [<ffffffff818322fc>] ret_from_fork+0x7c/0xb0
[    1.866946]  [<ffffffff81817af0>] ? rest_init+0x90/0x90
[    1.872923] Code: 41 56 41 55 41 54 53 48 83 ec 28 89 75 bc 0f ae f0 9c 58 66 66 90 66 90 48 89 45 b0 fa 66 66 90 66 66 90 65 8b 04 25 2
c b0 00 00 <4c> 8b 25 70 15 fc 7e 89 45 c8 65 4c 03 24 25 a8 dc 00 00 48 63
[    1.898786] RIP  [<ffffffff8104c8c9>] __x2apic_send_IPI_mask+0x39/0x190
[    1.906386]  RSP <ffff8810273ffc48>
[    1.910419] CR2: 000000000000de40
[    1.914261] ---[ end trace 840db19b2eaea46d ]---
[    1.919556] Kernel panic - not syncing: Fatal exception

Thanks,
Fengguang