From: Keith Busch <keith.busch@intel.com>
To: Wenbo Wang <wenbo.wang@memblaze.com>
Cc: Jens Axboe <axboe@fb.com>, Wenbo Wang <mail_weber_wang@163.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
"Wenwei.Tao" <wenwei.tao@memblaze.com>
Subject: Re: [PATCH] NVMe: do not touch sq door bell if nvmeq has been suspended
Date: Tue, 2 Feb 2016 17:25:03 +0000 [thread overview]
Message-ID: <20160202172503.GC10728@localhost.localdomain> (raw)
In-Reply-To: <BJXPR01MB19940BA759DBBADC6BF6BD2E0DF0@BJXPR01MB199.CHNPR01.prod.partner.outlook.cn>
On Tue, Feb 02, 2016 at 07:15:57AM +0000, Wenbo Wang wrote:
> Jens,
>
> I did the following test to validate the issue.
>
> 1. Modify code as below to increase the chance of races.
> Add 10s delay after nvme_dev_unmap() in nvme_dev_disable()
> Add 10s delay before __nvme_submit_cmd()
If running sync IO, preempt is disabled. You can't just put a 10 second
delay there. Wouldn't you hit a "scheduling while atomic" bug instead?
If blk-mq is running the h/w context from its work queue, that might
be a different issue. Maybe we can change the "cancel_delayed_work" to
"cancel_delayed_work_sync" in blk_mq_stop_hw_queues.
If there's still a window where blk-mq can insert a request after the
driver requested to stop queues, I think we should try to close it with
the block layer.
next prev parent reply other threads:[~2016-02-02 17:25 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-02-01 15:42 [PATCH] NVMe: do not touch sq door bell if nvmeq has been suspended Wenbo Wang
2016-02-01 15:59 ` Busch, Keith
2016-02-01 16:17 ` Wenbo Wang
2016-02-01 16:54 ` Jens Axboe
[not found] ` <BJXPR01MB19940BA759DBBADC6BF6BD2E0DF0@BJXPR01MB199.CHNPR01.prod.partner.outlook.cn>
2016-02-02 12:41 ` Sagi Grimberg
2016-02-02 14:27 ` Keith Busch
2016-02-02 14:33 ` Sagi Grimberg
2016-02-02 14:46 ` Keith Busch
2016-02-02 17:20 ` Sagi Grimberg
2016-02-02 17:25 ` Keith Busch [this message]
2016-02-03 14:41 ` Keith Busch
[not found] ` <BJXPR01MB1992FFD0706FCD368F5AD16E0D00@BJXPR01MB199.CHNPR01.prod.partner.outlook.cn>
2016-02-03 16:38 ` Keith Busch
[not found] ` <BJXPR01MB19916231021454BD8731EBDE0D30@BJXPR01MB199.CHNPR01.prod.partner.outlook.cn>
2016-02-07 13:41 ` Sagi Grimberg
2016-02-08 15:01 ` Keith Busch
[not found] ` <BJXPR01MB199E172F7B186281D1C7179E0D60@BJXPR01MB199.CHNPR01.prod.partner.outlook.cn>
2016-02-09 22:55 ` Keith Busch
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