Re: lockdep whine in 2.6.26-rc2-mm1

[Greg KH <greg@xxxxxxxxx>]

On Wed, May 14, 2008 at 12:09:33AM -0700, Andrew Morton wrote:
> 
> =============================================
> [ INFO: possible recursive locking detected ]
> 2.6.26-rc2-mm1 #15
> ---------------------------------------------
> modprobe/942 is trying to acquire lock:
>  (&cls->mutex){--..}, at: [<ffffffff811b431e>] device_add+0x43d/0x57a
> 
> but task is already holding lock:
>  (&cls->mutex){--..}, at: [<ffffffff811b6787>] class_interface_register+0x48/0xbd
> 
> other info that might help us debug this:
> 1 lock held by modprobe/942:
>  #0:  (&cls->mutex){--..}, at: [<ffffffff811b6787>] class_interface_register+0x48/0xbd
> 
> stack backtrace:
> Pid: 942, comm: modprobe Not tainted 2.6.26-rc2-mm1 #15
> 
> Call Trace:
>  [<ffffffff81056be1>] __lock_acquire+0x90d/0xc50
>  [<ffffffff8100c50f>] ? restore_args+0x0/0x30
>  [<ffffffff811b431e>] ? device_add+0x43d/0x57a
>  [<ffffffff81057276>] lock_acquire+0x91/0xb7
>  [<ffffffff811b431e>] ? device_add+0x43d/0x57a
>  [<ffffffff812b23ab>] mutex_lock_nested+0xf2/0x278
>  [<ffffffff811b431e>] ? device_add+0x43d/0x57a
>  [<ffffffff812b3acd>] ? _spin_unlock+0x23/0x28
>  [<ffffffff811b431e>] device_add+0x43d/0x57a
>  [<ffffffff811b4471>] device_register+0x16/0x1b
>  [<ffffffff811b4555>] device_create+0xdf/0x112
>  [<ffffffff81055fdc>] ? trace_hardirqs_on+0xd/0xf
>  [<ffffffff81055fdc>] ? trace_hardirqs_on+0xd/0xf
>  [<ffffffff812b1fe1>] ? mutex_unlock+0x9/0xb
>  [<ffffffff811b79b7>] ? kobj_map+0x113/0x124
>  [<ffffffff810ac0f5>] ? exact_lock+0x0/0x14
>  [<ffffffff810abd09>] ? exact_match+0x0/0x9
>  [<ffffffffa00ec448>] :sg:sg_add+0x2a3/0x3bd
>  [<ffffffff811b67b6>] class_interface_register+0x77/0xbd
>  [<ffffffffa005d869>] :scsi_mod:scsi_register_interface+0x11/0x13
>  [<ffffffffa00d50a3>] :sg:init_sg+0xa3/0x155
>  [<ffffffff8105ea8f>] sys_init_module+0x1823/0x197a
>  [<ffffffff810c45bc>] ? seq_release+0x0/0x56
>  [<ffffffff8100bebb>] system_call_after_swapgs+0x7b/0x80

I'm guessing that this is due to David's "change the semaphore to a
mutex" patch that you have in your tree, but I refused to take as I was
worried about just this issue :)

David, any thoughts?

> Driver 'sr' needs updating - please use bus_type methods

This is not the same issue, last I looked Kay and James were working on
resolving this.

thanks,

greg k-h
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