linux-kernel - Re: LOCKDEP warning due to ext_devt

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Message-ID: <55673E9F.6040200@fb.com>
Date:	Thu, 28 May 2015 10:13:19 -0600
From:	Jens Axboe <axboe@...com>
To:	NeilBrown <neilb@...e.de>
CC:	Keith Busch <keith.busch@...el.com>,
	lkml <linux-kernel@...r.kernel.org>
Subject: Re: LOCKDEP warning due to ext_devt_lock

On 05/27/2015 09:45 PM, NeilBrown wrote:
> On Wed, 27 May 2015 21:32:21 -0600 Jens Axboe <axboe@...com> wrote:
>
>> On 05/27/2015 08:32 PM, NeilBrown wrote:
>>>
>>> Hi Keith,
>>>    I'm getting lockdep warning around use of ext_devt_lock.
>>>
>>> [11428.266019] inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage.
>>>
>>>    As you say in
>>>       2da78092dda1 ("block: Fix dev_t minor allocation lifetime")
>>> ext_devt_lock can be taken from call_rcu's soft-irq.
>>> I think that means it should always use the _irq verion of spinlock.
>>
>> Wouldn't spin_lock_bh() and friends suffice then?
>>
>
> Quite possibly.  I've never actually used those so I don't tend to think
> about them.  But only reflection I think they would be exactly right.
> I'll modify my patch for future testing.
>
> BTW, did you get my:
>
>     [PATCH v2] block: discard bdi_unregister() in favour of bdi_destroy()
>
> ??  I haven't seen it appear in your 'block' tree.

I missed that, thanks for the reminder. I've queued it up for this series.

-- 
Jens Axboe

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