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Date:   Fri, 16 Jun 2023 07:48:00 +0200
From:   Christoph Hellwig <hch@lst.de>
To:     Ming Lei <ming.lei@redhat.com>
Cc:     Keith Busch <kbusch@kernel.org>, Jens Axboe <axboe@kernel.dk>,
        Christoph Hellwig <hch@lst.de>,
        Sagi Grimberg <sagi@grimberg.me>,
        linux-nvme@lists.infradead.org, Yi Zhang <yi.zhang@redhat.com>,
        linux-block@vger.kernel.org, Chunguang Xu <brookxu.cn@gmail.com>
Subject: Re: [PATCH 1/4] blk-mq: add API of blk_mq_unfreeze_queue_force
Message-ID: <20230616054800.GA28499@lst.de>
References: <20230615143236.297456-1-ming.lei@redhat.com> <20230615143236.297456-2-ming.lei@redhat.com> <ZIsrSyEqWMw8/ikq@kbusch-mbp.dhcp.thefacebook.com> <ZIsxt7Q2nmiLNTX2@ovpn-8-16.pek2.redhat.com>
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On Thu, Jun 15, 2023 at 11:43:51PM +0800, Ming Lei wrote:
> On Thu, Jun 15, 2023 at 09:16:27AM -0600, Keith Busch wrote:
> > On Thu, Jun 15, 2023 at 10:32:33PM +0800, Ming Lei wrote:
> > > NVMe calls freeze/unfreeze in different contexts, and controller removal
> > > may break in-progress error recovery, then leave queues in frozen state.
> > > So cause IO hang in del_gendisk() because pending writeback IOs are
> > > still waited in bio_queue_enter().
> > 
> > Shouldn't those writebacks be unblocked by the existing check in
> > bio_queue_enter, test_bit(GD_DEAD, &disk->state))? Or are we missing a
> > disk state update or wakeup on this condition?
> 
> GD_DEAD is only set if the device is really dead, then all pending IO
> will be failed.

del_gendisk also sets GD_DEAD early on.