Just FYI. I got an one shot oops and never managed to reproduce it...

[    0.137800] --------------------
[    0.137983]   remote IPI:
[    0.135979] BUG: unable to handle kernel paging request at cd478004
[    0.135979] IP: [<c126b7b1>] restore_all_notrace+0x4/0x18
[    0.135979] *pde = 01fea067 *pte = 0d478160 
[    0.135979] Oops: 0000 [#1] SMP DEBUG_PAGEALLOC
[    0.135979] Modules linked in:
[    0.135979] Pid: 0, comm: swapper/1 Not tainted 3.6.0-rc4-00057-g9450d57 #160 Bochs Bochs
[    0.135979] EIP: 0060:[<c126b7b1>] EFLAGS: 00010082 CPU: 1
[    0.135979] EIP is at restore_all_notrace+0x4/0x18
[    0.135979] EAX: 00010086 EBX: cd45deec ECX: c10279e0 EDX: 00000000
[    0.135979] ESI: cd45c000 EDI: c103ab60 EBP: cd45defc ESP: cd477fc4
[    0.135979]  DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
[    0.135979] CR0: 8005003b CR2: cd478004 CR3: 0156b000 CR4: 00000690
[    0.135979] DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
[    0.135979] DR6: ffff0ff0 DR7: 00000400
[    0.135979] Process swapper/1 (pid: 0, ti=cd476000 task=cd454000 task.ti=cd45c000)
[    0.135979] Stack:
[    0.135979]  cd45deec cd454000 cd454000 cd45c000 c103ab60 cd45defc 00000002 0000007b
[    0.135979]  0000007b 000000d8 000000e0 00000002 c10051b5 00000060 00010086
[    0.135979] Call Trace:
[    0.135979]  [<c103ab60>] ? ftrace_define_fields_irq_handler_entry+0x80/0x80
[    0.135979]  [<c10051b5>] ? do_softirq+0x85/0x110
[    0.135979]  <IRQ> 
[    0.135979]  [<c103b176>] irq_exit+0x96/0xc0
[    0.135979]  [<c126c5ce>] smp_apic_timer_interrupt+0x5e/0x8d
[    0.135979]  [<c116d678>] ? trace_hardirqs_off_thunk+0xc/0x14
[    0.135979]  [<c126ba92>] apic_timer_interrupt+0x36/0x3c
[    0.135979]  [<c1027aa0>] ? native_irq_enable+0x10/0x10
[    0.135979]  [<c1027aa5>] ? native_safe_halt+0x5/0x10
[    0.135979]  [<c100bdf9>] default_idle+0x69/0x470
[    0.135979]  [<c100cc2f>] cpu_idle+0xbf/0x100
[    0.135979]  [<c1260772>] start_secondary+0x21c/0x222
[    0.135979] Code: 00 00 00 00 e8 dd 1e f0 ff 8b 4d 08 f7 c1 ff fe 00 10 0f 85 12 01 00 00 f7 44 24 38 00 02 00 00 74 05 e8 af 1e f0 ff 8b 44 24 38 <8a> 64 24 40 8a 44 24 34 25 03 04 02 00 3d 03 04 00 00 74 17 5b
[    0.135979] EIP: [<c126b7b1>] restore_all_notrace+0x4/0x18 SS:ESP 0068:cd477fc4
[    0.135979] CR2: 00000000cd478004

The bug happens on (but is obviously not caused by):

tree:   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git sched/urgent
head:   9450d57eab5cad36774c297da123062744472588
commit: 9450d57eab5cad36774c297da123062744472588 [1/1] sched: Fix kernel-doc warnings in kernel/sched/fair.c

Thanks,
Fengguang