From: Jens Axboe <axboe@kernel.dk>
To: Mike Christie <mchristi@redhat.com>,
josef@toxicpanda.com, linux-block@vger.kernel.org
Cc: stable@vger.kernel.org
Subject: Re: [PATCH 1/1] nbd: fix max number of supported devs
Date: Tue, 20 Aug 2019 12:44:44 -0600 [thread overview]
Message-ID: <2c9a0b27-6761-f973-8e49-82e23b105e46@kernel.dk> (raw)
In-Reply-To: <20190804191006.5359-1-mchristi@redhat.com>
On 8/4/19 1:10 PM, Mike Christie wrote:
> This fixes a bug added in 4.10 with commit:
>
> commit 9561a7ade0c205bc2ee035a2ac880478dcc1a024
> Author: Josef Bacik <jbacik@fb.com>
> Date: Tue Nov 22 14:04:40 2016 -0500
>
> nbd: add multi-connection support
>
> that limited the number of devices to 256. Before the patch we could
> create 1000s of devices, but the patch switched us from using our
> own thread to using a work queue which has a default limit of 256
> active works.
>
> The problem is that our recv_work function sits in a loop until
> disconnection but only handles IO for one connection. The work is
> started when the connection is started/restarted, but if we end up
> creating 257 or more connections, the queue_work call just queues
> connection257+'s recv_work and that waits for connection 1 - 256's
> recv_work to be disconnected and that work instance completing.
>
> Instead of reverting back to kthreads, this has us allocate a
> workqueue_struct per device, so we can block in the work.
Applied for 5.4, thanks Mike.
--
Jens Axboe
prev parent reply other threads:[~2019-08-20 18:44 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-04 19:10 [PATCH 1/1] nbd: fix max number of supported devs Mike Christie
2019-08-05 18:19 ` Sasha Levin
2019-08-13 16:16 ` Josef Bacik
2019-08-20 18:44 ` Jens Axboe [this message]
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