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From: Ming Lei <tom.leiming@gmail.com>
To: Halil Pasic <pasic@linux.ibm.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
	Jason Wang <jasowang@redhat.com>, Jens Axboe <axboe@kernel.dk>,
	linux-block <linux-block@vger.kernel.org>,
	linux-s390 <linux-s390@vger.kernel.org>,
	Cornelia Huck <cohuck@redhat.com>, Ram Pai <linuxram@us.ibm.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux Virtualization <virtualization@lists.linux-foundation.org>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Stefan Hajnoczi <stefanha@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	"Lendacky, Thomas" <Thomas.Lendacky@amd.com>,
	Viktor Mihajlovski <mihajlov@linux.ibm.com>
Subject: Re: [PATCH 1/2] virtio-blk: fix hw_queue stopped on arbitrary error
Date: Tue, 18 Feb 2020 10:21:18 +0800	[thread overview]
Message-ID: <CACVXFVNiADTW_vLVc1bUSa0CoViLbVzoMnSJW4=sx=MCE-xUPw@mail.gmail.com> (raw)
In-Reply-To: <20200213123728.61216-2-pasic@linux.ibm.com>

On Thu, Feb 13, 2020 at 8:38 PM Halil Pasic <pasic@linux.ibm.com> wrote:
>
> Since nobody else is going to restart our hw_queue for us, the
> blk_mq_start_stopped_hw_queues() is in virtblk_done() is not sufficient
> necessarily sufficient to ensure that the queue will get started again.
> In case of global resource outage (-ENOMEM because mapping failure,
> because of swiotlb full) our virtqueue may be empty and we can get
> stuck with a stopped hw_queue.
>
> Let us not stop the queue on arbitrary errors, but only on -EONSPC which
> indicates a full virtqueue, where the hw_queue is guaranteed to get
> started by virtblk_done() before when it makes sense to carry on
> submitting requests. Let us also remove a stale comment.

The generic solution may be to stop queue only when there is any
in-flight request
not completed.

Checking -ENOMEM may not be enough, given -EIO can be returned from
virtqueue_add()
too in case of dma map failure.

Thanks,

  parent reply	other threads:[~2020-02-18  2:21 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-02-13 12:37 [PATCH 0/2] virtio-blk: improve handling of DMA mapping failures Halil Pasic
2020-02-13 12:37 ` [PATCH 1/2] virtio-blk: fix hw_queue stopped on arbitrary error Halil Pasic
2020-02-14 18:20   ` dongli.zhang
2020-02-17 13:08     ` Halil Pasic
2020-02-18  2:21   ` Ming Lei [this message]
2020-02-18 12:35     ` Halil Pasic
2020-02-19  1:46       ` Ming Lei
2020-02-19 15:42         ` Halil Pasic
2020-02-13 12:37 ` [PATCH 2/2] virtio-blk: improve virtqueue error to BLK_STS Halil Pasic
2020-02-19 15:11 ` [PATCH 0/2] virtio-blk: improve handling of DMA mapping failures Stefan Hajnoczi
2020-03-03 14:12 ` Halil Pasic
2020-03-03 14:49   ` Michael S. Tsirkin
2020-03-03 17:02     ` Halil Pasic

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