From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755919AbcFGUA3 (ORCPT ); Tue, 7 Jun 2016 16:00:29 -0400 Received: from mail-bl2on0076.outbound.protection.outlook.com ([65.55.169.76]:56160 "EHLO na01-bl2-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754898AbcFGUAW (ORCPT ); Tue, 7 Jun 2016 16:00:22 -0400 Authentication-Results: spf=pass (sender IP is 63.163.107.21) smtp.mailfrom=sandisk.com; vger.kernel.org; dkim=none (message not signed) header.d=none;vger.kernel.org; dmarc=bestguesspass action=none header.from=sandisk.com; X-AuditID: ac160c69-33fff70000000bcf-f9-575726c6804e Subject: Re: [RFC] IB/srp: Remove create_workqueue To: Tejun Heo References: <20160607181617.GA6556@Karyakshetra> <20160607192106.GY31708@htj.duckdns.org> CC: Bhaktipriya Shridhar , Doug Ledford , Sean Hefty , Hal Rosenstock , "linux-rdma@vger.kernel.org" , "linux-kernel@vger.kernel.org" From: Bart Van Assche Message-ID: Date: Tue, 7 Jun 2016 13:00:13 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.1.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFmphkeLIzCtJLcpLzFFi42JZI8azSPekWni4weZPnBZvfkxltHh5/gOr xcbNExktLu+aw2bx7FAvi0Xz+g0sFr+WH2V0YPfYOesuu8fiPS+ZPDat6mTzeL/vKpvH501y AaxRXDYpqTmZZalF+nYJXBm3T81jLujkrJh89w1zA+Ma9i5GTg4JAROJX3cuMHYxcnEICcxl kpj+9xczhLOdUWL7u0VsMFVPF71jhUgsZZRoaFoI1MLBISxgJHHypSpIjYiArMSVaQ+hJh1l lGj9+BzMYRZYxiTxeM1UFpAqNqCGb+9ngtm8AnYSPx+dYgaxWQRUJI7ceskEYosKREh8+v2F FaJGUOLkzCdg9ZwC9hIzli9nBLGZBSwkZs4/D2XLS2x/OwfsbAmBk6wSj6/tBDtbSEBd4uSS +UwTGIVnIZk1C0n/LCT9CxiZVzGK5WbmFOempxYYmuoVJ+alZBZn6yXn525ihMRN5g7Gu0+8 DzEKcDAq8fDu+BIaLsSaWFZcmXuIUYKDWUmE104lPFyINyWxsiq1KD++qDQntfgQozQHi5I4 r9u9L2FCAumJJanZqakFqUUwWSYOTqkGxg13jHp+8YVqXJ53/Px8n6bqci0T9V/L1Ry7atWe 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fcd9ea9c-ae8c-460c-ab3c-3db42d7ac64d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=fcd9ea9c-ae8c-460c-ab3c-3db42d7ac64d;Ip=[63.163.107.21];Helo=[milsmgep15.sandisk.com] X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DM2PR02MB494 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/07/2016 12:56 PM, Bart Van Assche wrote: > 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. See also commit bcc059103591 for the details. Bart.