Re: 4.14: WARNING: CPU: 4 PID: 2895 at block/blk-mq.c:1144 with virtio-blk (also 4.12 stable)

To: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Subject: Re: 4.14: WARNING: CPU: 4 PID: 2895 at block/blk-mq.c:1144 with virtio-blk (also 4.12 stable)
From: Christoph Hellwig <hch@xxxxxx>
Date: Thu, 23 Nov 2017 15:08:55 +0100
Cc: Jens Axboe <axboe@xxxxxxxxx>, Bart Van Assche <Bart.VanAssche@xxxxxxx>, "virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx" <virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx>, "linux-block@xxxxxxxxxxxxxxx" <linux-block@xxxxxxxxxxxxxxx>, "mst@xxxxxxxxxx" <mst@xxxxxxxxxx>, "jasowang@xxxxxxxxxx" <jasowang@xxxxxxxxxx>, "linux-kernel@xxxxxxxxxxxxxxx" <linux-kernel@xxxxxxxxxxxxxxx>, Christoph Hellwig <hch@xxxxxx>
In-reply-to: <20171123140208.GA28914@lst.de>
User-agent: Mutt/1.5.17 (2007-11-01)

Ok, it helps to make sure we're actually doing I/O from the CPU,
I've reproduced it now.

References:
- Re: 4.14: WARNING: CPU: 4 PID: 2895 at block/blk-mq.c:1144 with virtio-blk
  - From: Jens Axboe
- Re: 4.14: WARNING: CPU: 4 PID: 2895 at block/blk-mq.c:1144 with virtio-blk
  - From: Christian Borntraeger
- Re: 4.14: WARNING: CPU: 4 PID: 2895 at block/blk-mq.c:1144 with virtio-blk
  - From: Jens Axboe
- Re: 4.14: WARNING: CPU: 4 PID: 2895 at block/blk-mq.c:1144 with virtio-blk
  - From: Christian Borntraeger
- Re: 4.14: WARNING: CPU: 4 PID: 2895 at block/blk-mq.c:1144 with virtio-blk
  - From: Christian Borntraeger
- Re: 4.14: WARNING: CPU: 4 PID: 2895 at block/blk-mq.c:1144 with virtio-blk (also 4.12 stable)
  - From: Christian Borntraeger
- Re: 4.14: WARNING: CPU: 4 PID: 2895 at block/blk-mq.c:1144 with virtio-blk (also 4.12 stable)
  - From: Jens Axboe
- Re: 4.14: WARNING: CPU: 4 PID: 2895 at block/blk-mq.c:1144 with virtio-blk (also 4.12 stable)
  - From: Jens Axboe
- Re: 4.14: WARNING: CPU: 4 PID: 2895 at block/blk-mq.c:1144 with virtio-blk (also 4.12 stable)
  - From: Christian Borntraeger
- Re: 4.14: WARNING: CPU: 4 PID: 2895 at block/blk-mq.c:1144 with virtio-blk (also 4.12 stable)
  - From: Christoph Hellwig