Trace one (full config/dmesg attached): [ 0.042794] init IO_APIC IRQs [ 0.043305] apic 2 pin 0 not connected [ 0.043953] BUG: scheduling while atomic: swapper/0/1/0x10000002 [ 0.044017] no locks held by swapper/0/1. [ 0.044692] Pid: 1, comm: swapper/0 Not tainted 3.6.0-rc1-00420-gb7aebb9 #34 [ 0.045861] Call Trace: [ 0.048071] [] __schedule_bug+0x5e/0x70 [ 0.048890] [] __schedule+0x91/0xb10 [ 0.049660] [] ? vsnprintf+0x33a/0x450 [ 0.050444] [] ? lg_local_lock+0x6/0x70 [ 0.051256] [] ? wait_for_xmitr+0x31/0x90 [ 0.052019] [] ? do_raw_spin_unlock+0xa5/0xf0 [ 0.052903] [] ? _raw_spin_unlock+0x22/0x30 [ 0.053759] [] ? up+0x1b/0x70 [ 0.054421] [] __cond_resched+0x1b/0x30 [ 0.055228] [] _cond_resched+0x45/0x50 [ 0.056020] [] mutex_lock_nested+0x28/0x370 [ 0.056884] [] ? console_unlock+0x3a2/0x4e0 [ 0.057741] [] __irq_alloc_descs+0x39/0x1c0 [ 0.058589] [] io_apic_setup_irq_pin+0x2c/0x310 [ 0.060042] [] setup_IO_APIC+0x101/0x744 [ 0.060878] [] ? clear_IO_APIC+0x31/0x50 [ 0.061695] [] native_smp_prepare_cpus+0x538/0x680 [ 0.062644] [] ? do_one_initcall+0x12c/0x12c [ 0.063517] [] ? do_one_initcall+0x12c/0x12c [ 0.064016] [] kernel_init+0x4b/0x17f [ 0.064790] [] ? do_one_initcall+0x12c/0x12c [ 0.065660] [] kernel_thread_helper+0x6/0x10 [ 0.066592] IOAPIC[0]: Set routing entry (2-1 -> 0x41 -> IRQ 1 Mode:0 Active:0 Dest:1) [ 0.068045] IOAPIC[0]: Set routing entry (2-2 -> 0x51 -> IRQ 0 Mode:0 Active:0 Dest:1) Trace two (triggered by another config): [ 0.288018] tlb_flushall_shift is 0xffffffff [ 0.316019] Freeing SMP alternatives: 20k freed [ 0.364022] BUG: scheduling while atomic: swapper/0/1/0x10000002 [ 0.364022] no locks held by swapper/0/1. [ 0.368023] Pid: 1, comm: swapper/0 Not tainted 3.6.0-rc1 #1 [ 0.368023] Call Trace: [ 0.368023] [<79812e23>] __schedule_bug+0x41/0x53 [ 0.372023] [<79820393>] __schedule+0x62/0x488 [ 0.376023] [<792d17ae>] ? radix_tree_lookup+0xa/0xc [ 0.376023] [<79071f4e>] ? rcu_irq_exit+0x61/0x66 [ 0.376023] [<79026be7>] ? irq_exit+0x60/0x6c [ 0.376023] [<790035df>] ? do_IRQ+0x6c/0x80 [ 0.380023] [<7903d794>] __cond_resched+0x16/0x26 [ 0.380023] [<79820888>] _cond_resched+0x13/0x1c [ 0.380023] [<7909f30a>] slab_pre_alloc_hook.isra.44+0x2e/0x33 [ 0.380023] [<790a09c6>] kmem_cache_alloc+0x1b/0xbb [ 0.384024] [<792ce416>] ? alloc_cpumask_var_node+0x1a/0x72 [ 0.384024] [<792ce416>] alloc_cpumask_var_node+0x1a/0x72 [ 0.384024] [<792ce486>] alloc_cpumask_var+0xb/0xd [ 0.388024] [<792ce493>] zalloc_cpumask_var+0xb/0xd [ 0.388024] [<79bfe1fd>] native_smp_prepare_cpus+0x93/0x380 [ 0.388024] [<79bf6a7e>] ? do_one_initcall+0x10c/0x10c [ 0.388024] [<79bf6ac6>] kernel_init+0x48/0x16e [ 0.392024] [<79bf6a7e>] ? do_one_initcall+0x10c/0x10c [ 0.392024] [<7982241e>] kernel_thread_helper+0x6/0xd [ 0.400025] smpboot: SMP disabled [ 0.400025] Performance Events: Thanks, Fengguang