Greetings,

Here is an one shot oops that I've not managed to reproduce after one
night's tests..

[ 1238.277618] EXT4-fs (vdc): couldn't mount as ext2 due to feature incompatibilities
[ 1541.816024] hrtimer: interrupt took 21027368 ns
[ 2343.000017] BUG: spinlock recursion on CPU#0, fallocate/25287
[ 2343.000017]  lock: 0xffff88001f5d3b00, .magic: dead4ead, .owner: fallocate/25287, .owner_cpu: -1
[ 2343.000017] Pid: 25287, comm: fallocate Not tainted 3.6.0-rc4+ #4189
[ 2343.000017] Call Trace:
[ 2343.000017]  <IRQ>  [<ffffffff819acaea>] spin_dump+0x8c/0x91
[ 2343.000017]  [<ffffffff819acb15>] spin_bug+0x26/0x28
[ 2343.000017]  [<ffffffff8142fee6>] do_raw_spin_lock+0x41/0xf3
[ 2343.000017]  [<ffffffff819b679e>] _raw_spin_lock+0x56/0x69
[ 2343.000017]  [<ffffffff810a33b8>] ? sched_rt_period_timer+0x85/0x23e
[ 2343.000017]  [<ffffffff819b6f9c>] ? _raw_spin_unlock+0x29/0x2e
[ 2343.000017]  [<ffffffff810a33b8>] sched_rt_period_timer+0x85/0x23e
[ 2343.000017]  [<ffffffff810a3333>] ? post_schedule_rt+0x10/0x10
[ 2343.000017]  [<ffffffff8108ea23>] __run_hrtimer+0xbe/0x19e
[ 2343.000017]  [<ffffffff8108f2d4>] hrtimer_interrupt+0xd9/0x1c0
[ 2343.000017]  [<ffffffff819bf9ea>] smp_apic_timer_interrupt+0x86/0x99
[ 2343.000017]  [<ffffffff819bea6f>] apic_timer_interrupt+0x6f/0x80
[ 2343.000017]  <EOI>  [<ffffffff819b7430>] ? retint_restore_args+0x13/0x13
[ 2343.000017]  [<ffffffff8109ce04>] ? local_clock+0x1d/0x5a
[ 2343.000017]  [<ffffffff810c2555>] ? csd_lock_wait.isra.3+0xd/0x14
[ 2343.000017]  [<ffffffff810534ca>] ? native_send_call_func_single_ipi+0x36/0x38
[ 2343.000017]  [<ffffffff810c2602>] generic_exec_single+0x84/0x93
[ 2343.000017]  [<ffffffff8106117b>] ? do_flush_tlb_all+0x41/0x41
[ 2343.000017]  [<ffffffff810c2783>] smp_call_function_single+0x172/0x197
[ 2343.000017]  [<ffffffff8106117b>] ? do_flush_tlb_all+0x41/0x41
[ 2343.000017]  [<ffffffff810c2a01>] smp_call_function_many+0x121/0x238
[ 2343.000017]  [<ffffffff8106117b>] ? do_flush_tlb_all+0x41/0x41
[ 2343.000017]  [<ffffffff8106122e>] native_flush_tlb_others+0x2e/0x30
[ 2343.000017]  [<ffffffff81061465>] flush_tlb_mm_range+0x1da/0x1e9
[ 2343.000017]  [<ffffffff81133c3c>] tlb_flush_mmu+0x42/0x7f
[ 2343.000017]  [<ffffffff81133c95>] tlb_finish_mmu+0x1c/0x41
[ 2343.000017]  [<ffffffff8113b243>] exit_mmap+0xc9/0x133
[ 2343.000017]  [<ffffffff81066b02>] mmput+0x50/0xb0
[ 2343.000017]  [<ffffffff8106c8f5>] exit_mm+0x108/0x115
[ 2343.000017]  [<ffffffff819b6fcf>] ? _raw_spin_unlock_irq+0x2e/0x39
[ 2343.000017]  [<ffffffff8106e1f7>] do_exit+0x22c/0x82e
[ 2343.000017]  [<ffffffff819b7415>] ? retint_swapgs+0x13/0x1b
[ 2343.000017]  [<ffffffff8106ea82>] do_group_exit+0x7b/0xba
[ 2343.000017]  [<ffffffff8106ead8>] sys_exit_group+0x17/0x17
[ 2343.000017]  [<ffffffff819be150>] tracesys+0xdd/0xe2

Thanks,
Fengguang