FYI, yet another dmesg, hope it helps debugging :) x86_64-randconfig-s284 b______b___b_BBBBBB -- 12: f411932 13: B c2865bb 2012-09-10 kvm-waimea [ 2.295689] double fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC 14: B 549bf9c 2012-09-10 kvm-inn [ 2.779554] double fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC 15: B 4e382ff 2012-09-10 kvm-inn [ 2.751103] double fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC 16: B 23ddf94 2012-09-10 kvm-stoakley [ 3.470572] double fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC 17: B f117e2a 2012-09-10 kvm-inn [ 4.024677] divide error: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC [update_sd_lb_stats find_busiest_group load_balance lock_acquire idle_balance __schedule schedule worker_thread rescuer_thread kthread retint_restore_args __init_kthread_worker gs_change] 18: B a392720 2012-09-10 kvm-fat [ 2.739769] double fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC 18: B a392720 2012-09-10 kvm-inn [ 3.974984] double fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC 18: B a392720 2012-09-10 kvm-stoakley [ 3.471390] double fault: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC [ 4.022721] bus: 'serio': really_probe: probing driver atkbd with device serio1 [ 4.023973] atkbd: probe of serio1 rejects match -19 [ 4.024677] divide error: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC [ 4.025627] Modules linked in: [ 4.026041] CPU 0 [ 4.026282] Pid: 21, comm: kworker/0:1 Not tainted 3.6.0-rc3-00186-gf117e2a #47 Bochs Bochs [ 4.026414] RIP: 0010:[] [] update_sd_lb_stats+0x2a8/0x484 [ 4.026414] RSP: 0018:ffff8800001dfac0 EFLAGS: 00010046 [ 4.026414] RAX: 0000000000100000 RBX: ffff8800001dfcb0 RCX: 0000000000000000 [ 4.026414] RDX: 0000000000000000 RSI: 00000000000000ff RDI: 0000000000000000 [ 4.026414] RBP: ffff8800001dfb90 R08: ffff8800000812b8 R09: 0000000000000013 [ 4.026414] R10: ffffffff813be9d0 R11: ffff88000ddd3240 R12: 0000000000000000 [ 4.026414] R13: 0000000000000008 R14: ffff8800001dfba0 R15: ffff8800000812a0 [ 4.026414] FS: 0000000000000000(0000) GS:ffff88000dc00000(0000) knlGS:0000000000000000 [ 4.026414] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 4.026414] CR2: 0000000000000000 CR3: 00000000013a5000 CR4: 00000000000006b0 [ 4.026414] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 4.026414] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [ 4.026414] Process kworker/0:1 (pid: 21, threadinfo ffff8800001de000, task ffff880000172000) [ 4.026414] Stack: [ 4.026414] 00000000001d3240 ffff8800000812b8 ffff8800001dfd4c 00000000001d3240 [ 4.026414] 0000000000000001 0000000000000001 0000000000000000 0000000000000400 [ 4.026414] 0000000000000001 0000000000000400 00000000ffffffff ffff8800001dfb20 [ 4.026414] Call Trace: [ 4.026414] [] find_busiest_group+0x2c/0x1db [ 4.026414] [] load_balance+0xcb/0x5c5 [ 4.026414] [] ? lock_acquire+0xa6/0xb1 [ 4.026414] [] idle_balance+0x9c/0x111 [ 4.026414] [] __schedule+0x241/0x4bd [ 4.026414] [] schedule+0x60/0x62 [ 4.026414] [] worker_thread+0x21a/0x24b [ 4.026414] [] ? rescuer_thread+0x17d/0x17d [ 4.026414] [] kthread+0x73/0x7b [ 4.026414] [] kernel_thread_helper+0x4/0x10 [ 4.026414] [] ? retint_restore_args+0x13/0x13 [ 4.026414] [] ? __init_kthread_worker+0x55/0x55 [ 4.026414] [] ? gs_change+0x13/0x13 [ 4.026414] Code: 47 10 48 8b 15 3b b9 3a 00 48 3b 50 10 78 0b 8b 73 14 48 8b 3b e8 f8 fb ff ff 49 8b 57 10 48 8b 45 98 8b 4a 04 48 c1 e0 0a 31 d2 <48> f7 f1 48 8b 4d a0 48 89 45 90 31 c0 48 85 c9 74 09 48 8b 45 [ 4.026414] RIP [] update_sd_lb_stats+0x2a8/0x484 [ 4.026414] RSP Thanks, Fengguang