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From: Christoph Hellwig <hch@lst.de>
To: Ming Lei <ming.lei@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>, Keith Busch <kbusch@kernel.org>,
	Jens Axboe <axboe@kernel.dk>, 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
Date: Fri, 16 Jun 2023 09:27:21 +0200	[thread overview]
Message-ID: <20230616072721.GA30186@lst.de> (raw)
In-Reply-To: <ZIwNRu1zodp61PEO@ovpn-8-18.pek2.redhat.com>

On Fri, Jun 16, 2023 at 03:20:38PM +0800, Ming Lei wrote:
> > > > 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.
> 
> No.
> 
> The hang happens in fsync_bdev() of del_gendisk(), and there are IOs pending on
> bio_queue_enter().

What is the workload here?  If del_gendisk is called to remove a disk
that is in perfectly fine state and can do I/O, fsync_bdev should write
back data, which is what is exists for.  If the disk is dead, we should
have called blk_mark_disk_dead before.


  reply	other threads:[~2023-06-16  7:27 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-06-15 14:32 [PATCH 0/4] nvme: fix two kinds of IO hang from removing NSs Ming Lei
2023-06-15 14:32 ` [PATCH 1/4] blk-mq: add API of blk_mq_unfreeze_queue_force Ming Lei
2023-06-15 15:16   ` Keith Busch
2023-06-15 15:43     ` Ming Lei
2023-06-16  5:48       ` Christoph Hellwig
2023-06-16  7:20         ` Ming Lei
2023-06-16  7:27           ` Christoph Hellwig [this message]
2023-06-16  7:33             ` Ming Lei
2023-06-20  5:41           ` Christoph Hellwig
2023-06-20 10:01             ` Sagi Grimberg
2023-06-20 13:15             ` Ming Lei
2023-06-15 14:32 ` [PATCH 2/4] nvme: add nvme_unfreeze_force() Ming Lei
2023-06-15 14:32 ` [PATCH 3/4] nvme: unfreeze queues before removing namespaces Ming Lei
2023-06-15 14:32 ` [PATCH 4/4] nvme: unquiesce io queues when " Ming Lei

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