From: Bart Van Assche <bvanassche@acm.org>
To: Jens Axboe <axboe@kernel.dk>, Ming Lei <tom.leiming@gmail.com>,
linux-block <linux-block@vger.kernel.org>,
Omar Sandoval <osandov@fb.com>
Subject: Re: block: sbitmap related lockdep warning
Date: Mon, 03 Dec 2018 16:31:28 -0800 [thread overview]
Message-ID: <1543883488.185366.176.camel@acm.org> (raw)
In-Reply-To: <879e4f73-caa0-93e0-a6c3-3d53d1962cee@kernel.dk>
On Mon, 2018-12-03 at 15:24 -0700, Jens Axboe wrote:
> On 12/3/18 3:02 AM, Ming Lei wrote:
> > Hi,
> >
> > Just found there is sbmitmap related lockdep warning, not take a close
> > look yet, maybe
> > it is caused by recent sbitmap change.
> >
> > [1] test
> > - modprobe null_blk queue_mode=2 nr_devices=4 shared_tags=1
> > submit_queues=1 hw_queue_depth=1
> > - then run fio on the 4 null_blk devices
>
> This is a false positive - lockdep thinks that ->swap_lock needs to be
> IRQ safe since it's called with IRQs disabled from the
> blk_mq_mark_tag_wait() path. But we never grab the lock from IRQ
> context. I wonder how to teach lockdep about that...
There is probably a better solution, but one possible solution is to disable
lockdep checking for swap_lock by using lockdep_set_novalidate_class().
Bart.
next prev parent reply other threads:[~2018-12-04 0:31 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-03 10:02 block: sbitmap related lockdep warning Ming Lei
2018-12-03 22:24 ` Jens Axboe
2018-12-04 0:31 ` Bart Van Assche [this message]
2018-12-04 0:50 ` Jens Axboe
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