Re: [Bug #12612] hard lockup when interrupting cdda2wav

[Matthias Reichl <hias-vtPv7MOkFPkAvxtiuMwx3w@public.gmane.org>]

The bug is still present in 2.6.28.5:

=============================================
[ INFO: possible recursive locking detected ]
2.6.28.5-dbg #1
---------------------------------------------
swapper/0 is trying to acquire lock:
 (&q->__queue_lock){.+..}, at: [<ffffffff8040e615>] blk_put_request+0x25/0x60

but task is already holding lock:
 (&q->__queue_lock){.+..}, at: [<ffffffff8040e4fa>] blk_end_io+0x5a/0xa0

other info that might help us debug this:
1 lock held by swapper/0:
 #0:  (&q->__queue_lock){.+..}, at: [<ffffffff8040e4fa>] blk_end_io+0x5a/0xa0

stack backtrace:
Pid: 0, comm: swapper Not tainted 2.6.28.5-dbg #1
Call Trace:
 <IRQ>  [<ffffffff8026cd07>] __lock_acquire+0x1797/0x1930
 [<ffffffff806abf8b>] error_exit+0x29/0xa9
 [<ffffffff80521f40>] sg_rq_end_io+0x0/0x2e0
 [<ffffffff8026cf3a>] lock_acquire+0x9a/0xe0
 [<ffffffff8040e615>] blk_put_request+0x25/0x60
 [<ffffffff806ab973>] _spin_lock_irqsave+0x43/0x90
 [<ffffffff8040e615>] blk_put_request+0x25/0x60
 [<ffffffff8040e615>] blk_put_request+0x25/0x60
 [<ffffffff80520a94>] sg_finish_rem_req+0xa4/0x100
 [<ffffffff805221b8>] sg_rq_end_io+0x278/0x2e0
 [<ffffffff8040e2a1>] end_that_request_last+0x61/0x260
 [<ffffffff8040e508>] blk_end_io+0x68/0xa0
 [<ffffffff80508181>] scsi_end_request+0x41/0xd0
 [<ffffffff80508870>] scsi_io_completion+0x130/0x470
 [<ffffffff80413405>] blk_done_softirq+0x75/0x90
 [<ffffffff802488ab>] __do_softirq+0x9b/0x180
 [<ffffffff80213df3>] native_sched_clock+0x13/0x70
 [<ffffffff8020d6ec>] call_softirq+0x1c/0x30
 [<ffffffff8020f175>] do_softirq+0x65/0xa0
 [<ffffffff80248345>] irq_exit+0xa5/0xb0
 [<ffffffff8020f467>] do_IRQ+0x107/0x1d0
 [<ffffffff8020c7fb>] ret_from_intr+0x0/0xf
 <EOI>  [<ffffffff80214ba6>] mwait_idle+0x56/0x60
 [<ffffffff80214b9d>] mwait_idle+0x4d/0x60
 [<ffffffff8020b353>] cpu_idle+0x63/0xc0