linux-kernel - Re: [RFC] IB/srp: Remove create

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Message-ID: <bdf2c634-a765-eb97-5ca1-583d833b07c7@sandisk.com>
Date:	Tue, 7 Jun 2016 12:56:25 -0700
From:	Bart Van Assche <bart.vanassche@...disk.com>
To:	Tejun Heo <tj@...nel.org>
CC:	Bhaktipriya Shridhar <bhaktipriya96@...il.com>,
	Doug Ledford <dledford@...hat.com>,
	Sean Hefty <sean.hefty@...el.com>,
	Hal Rosenstock <hal.rosenstock@...il.com>,
	"linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [RFC] IB/srp: Remove create_workqueue

On 06/07/2016 12:21 PM, Tejun Heo wrote:
> On Tue, Jun 07, 2016 at 11:32:42AM -0700, Bart Van Assche wrote:
>> On 06/07/2016 11:16 AM, Bhaktipriya Shridhar wrote:
>>> alloc_workqueue replaces deprecated create_workqueue().
>>>
>>> A dedicated workqueue has been used since the workqueue srp_remove_wq with
>>> workitem &target->remove_work, is a work queue for the SRP target removal.
>>> WQ_MEM_RECLAIM has been set to ensure forward progress under memory
>>> pressure.
>>> Since there are only a fixed number of work items, explicit
>>> concurrency limit is unnecessary here.
>>>
>>> Is the workqueue being used on a memory reclaim path?
>>> Does it require WQ_MEM_RECLAIM?
>>
>> Hello Bhaktipriya,
>>
>> srp_remove_wq is used for SRP target port removal work only. This work is
>> neither queued from inside a shrinker nor by the page writeback code so I
>> think it is safe to drop WQ_MEM_RECLAIM.
>
> It should be able to use system_wq then.

No. I have tried that but that resulted in a deadlock.

Bart.