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From: Ming Lei <ming.lei@redhat.com>
To: Sagi Grimberg <sagi@grimberg.me>
Cc: Max Gurtovoy <maxg@mellanox.com>, Jens Axboe <axboe@kernel.dk>,
	"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
	"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>
Subject: Re: NVMe induced NULL deref in bt_iter()
Date: Tue, 4 Jul 2017 16:08:19 +0800	[thread overview]
Message-ID: <20170704080818.GA29053@ming.t460p> (raw)
In-Reply-To: <92224329-0933-4e80-94d6-2ba3c88f3f3e@grimberg.me>

On Tue, Jul 04, 2017 at 10:56:23AM +0300, Sagi Grimberg wrote:
> 
> > There are at least one case in which we have to use stop queues:
> > 
> > 	- when QUEUE_BUSY(now it becomes BLK_STS_RESOURCE) happens, some drivers
> > 	need to stop queues for avoiding to hurt CPU, such as virtio-blk, ...
> 
> Why isn't virtio_blk using blk_mq_delay_run_hw_queue like scsi does?

IMO it shouldn't be easy to figure out one perfect delay time, and it
should have been self-adaptive.

Also I think it might be possible to move this kind of stop action into
blk-mq core code, and not let drivers touch stop state. Finally we
may kill all stopping in drivers.

Thanks,
Ming

WARNING: multiple messages have this Message-ID (diff)
From: ming.lei@redhat.com (Ming Lei)
Subject: NVMe induced NULL deref in bt_iter()
Date: Tue, 4 Jul 2017 16:08:19 +0800	[thread overview]
Message-ID: <20170704080818.GA29053@ming.t460p> (raw)
In-Reply-To: <92224329-0933-4e80-94d6-2ba3c88f3f3e@grimberg.me>

On Tue, Jul 04, 2017@10:56:23AM +0300, Sagi Grimberg wrote:
> 
> > There are at least one case in which we have to use stop queues:
> > 
> > 	- when QUEUE_BUSY(now it becomes BLK_STS_RESOURCE) happens, some drivers
> > 	need to stop queues for avoiding to hurt CPU, such as virtio-blk, ...
> 
> Why isn't virtio_blk using blk_mq_delay_run_hw_queue like scsi does?

IMO it shouldn't be easy to figure out one perfect delay time, and it
should have been self-adaptive.

Also I think it might be possible to move this kind of stop action into
blk-mq core code, and not let drivers touch stop state. Finally we
may kill all stopping in drivers.

Thanks,
Ming

  reply	other threads:[~2017-07-04  8:08 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-30 17:26 NVMe induced NULL deref in bt_iter() Jens Axboe
2017-07-02 10:45 ` Max Gurtovoy
2017-07-02 10:45   ` Max Gurtovoy
2017-07-02 11:56   ` Sagi Grimberg
2017-07-02 11:56     ` Sagi Grimberg
2017-07-02 14:37     ` Max Gurtovoy
2017-07-02 14:37       ` Max Gurtovoy
2017-07-02 15:08       ` Sagi Grimberg
2017-07-02 15:08         ` Sagi Grimberg
2017-07-03  9:40     ` Ming Lei
2017-07-03  9:40       ` Ming Lei
2017-07-03 10:07       ` Sagi Grimberg
2017-07-03 10:07         ` Sagi Grimberg
2017-07-03 12:03         ` Ming Lei
2017-07-03 12:03           ` Ming Lei
2017-07-03 12:46           ` Max Gurtovoy
2017-07-03 12:46             ` Max Gurtovoy
2017-07-03 15:54             ` Ming Lei
2017-07-03 15:54               ` Ming Lei
2017-07-04  6:58               ` Sagi Grimberg
2017-07-04  6:58                 ` Sagi Grimberg
2017-07-04  7:56           ` Sagi Grimberg
2017-07-04  7:56             ` Sagi Grimberg
2017-07-04  8:08             ` Ming Lei [this message]
2017-07-04  8:08               ` Ming Lei
2017-07-04  9:14               ` Sagi Grimberg
2017-07-04  9:14                 ` Sagi Grimberg
2017-07-03 16:01   ` Jens Axboe
2017-07-03 16:01     ` Jens Axboe

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