From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B1928C2BB85 for ; Fri, 10 Apr 2020 03:12:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9420120A8B for ; Fri, 10 Apr 2020 03:12:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726681AbgDJDM1 (ORCPT ); Thu, 9 Apr 2020 23:12:27 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:33436 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726594AbgDJDM0 (ORCPT ); Thu, 9 Apr 2020 23:12:26 -0400 Received: by mail-pg1-f195.google.com with SMTP id d17so456751pgo.0; Thu, 09 Apr 2020 20:12:25 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:autocrypt :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=riLsCQbI8rWtquYxJsTgKqCXsr91BsaOod5Gd8OL/tY=; b=AcVxCVhitGWT7cX7BC3gMTShdwHIFV5P+Jx8Q5h0Qp1kliooiSyQCNr7uE1nIizppC Ygj1Z9CPNTWP6FI8YeNQuRpDxHP/njrgWzKvlbCMHc57JRKWkxXkzC2fCU5HB4cMOHE6 xGN7Vh0vo/wqar3SN9oZWL/4/do0C5gaDGNoC2v1LYcw4UpMGCh3LIGmJ6x2csMBGNaW S4ZJ6/pXzdtXtHzMMe53u3r7zNqzEY5KZCl9H8bF7eDLVpMksP78VAvMt9AcFnjbGGSm DK9S0SXDZ3pVSKop/meYukydamHAk85gb7sUu3rxj9wJt6Ce6dJboGs87OKLwtz7cVzc GmSA== X-Gm-Message-State: AGi0PuZ04j8Zq0FJwDUzdvmoav665rDlAIxlQBerp0iCZVMRnPLl9r/m /N7W7InMeWO1x7sL4i+9lrg= X-Google-Smtp-Source: APiQypJB9TbTwNuE4JRdnVGrOnnBOWWgxmCc4vJV5SidGuVHW3ci9n/1oxuQj7yHNMWcyR+ZersXAg== X-Received: by 2002:a65:5a4f:: with SMTP id z15mr2583848pgs.103.1586488344310; Thu, 09 Apr 2020 20:12:24 -0700 (PDT) Received: from ?IPv6:2601:647:4000:d7:ed4e:1b14:7fc4:cd73? ([2601:647:4000:d7:ed4e:1b14:7fc4:cd73]) by smtp.gmail.com with ESMTPSA id q6sm461549pja.34.2020.04.09.20.12.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 09 Apr 2020 20:12:23 -0700 (PDT) Subject: Re: [RFC v2 5/5] block: revert back to synchronous request_queue removal To: Luis Chamberlain , axboe@kernel.dk, viro@zeniv.linux.org.uk, gregkh@linuxfoundation.org, rostedt@goodmis.org, mingo@redhat.com, jack@suse.cz, ming.lei@redhat.com, nstange@suse.de, akpm@linux-foundation.org Cc: mhocko@suse.com, yukuai3@huawei.com, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Omar Sandoval , Hannes Reinecke , Michal Hocko References: <20200409214530.2413-1-mcgrof@kernel.org> <20200409214530.2413-6-mcgrof@kernel.org> From: Bart Van Assche Autocrypt: addr=bvanassche@acm.org; prefer-encrypt=mutual; keydata= mQENBFSOu4oBCADcRWxVUvkkvRmmwTwIjIJvZOu6wNm+dz5AF4z0FHW2KNZL3oheO3P8UZWr LQOrCfRcK8e/sIs2Y2D3Lg/SL7qqbMehGEYcJptu6mKkywBfoYbtBkVoJ/jQsi2H0vBiiCOy fmxMHIPcYxaJdXxrOG2UO4B60Y/BzE6OrPDT44w4cZA9DH5xialliWU447Bts8TJNa3lZKS1 AvW1ZklbvJfAJJAwzDih35LxU2fcWbmhPa7EO2DCv/LM1B10GBB/oQB5kvlq4aA2PSIWkqz4 3SI5kCPSsygD6wKnbRsvNn2mIACva6VHdm62A7xel5dJRfpQjXj2snd1F/YNoNc66UUTABEB AAG0JEJhcnQgVmFuIEFzc2NoZSA8YnZhbmFzc2NoZUBhY20ub3JnPokBOQQTAQIAIwUCVI67 igIbAwcLCQgHAwIBBhUIAgkKCwQWAgMBAh4BAheAAAoJEHFcPTXFzhAJ8QkH/1AdXblKL65M Y1Zk1bYKnkAb4a98LxCPm/pJBilvci6boefwlBDZ2NZuuYWYgyrehMB5H+q+Kq4P0IBbTqTa jTPAANn62A6jwJ0FnCn6YaM9TZQjM1F7LoDX3v+oAkaoXuq0dQ4hnxQNu792bi6QyVdZUvKc macVFVgfK9n04mL7RzjO3f+X4midKt/s+G+IPr4DGlrq+WH27eDbpUR3aYRk8EgbgGKvQFdD CEBFJi+5ZKOArmJVBSk21RHDpqyz6Vit3rjep7c1SN8s7NhVi9cjkKmMDM7KYhXkWc10lKx2 RTkFI30rkDm4U+JpdAd2+tP3tjGf9AyGGinpzE2XY1K5AQ0EVI67igEIAKiSyd0nECrgz+H5 PcFDGYQpGDMTl8MOPCKw/F3diXPuj2eql4xSbAdbUCJzk2ETif5s3twT2ER8cUTEVOaCEUY3 eOiaFgQ+nGLx4BXqqGewikPJCe+UBjFnH1m2/IFn4T9jPZkV8xlkKmDUqMK5EV9n3eQLkn5g lco+FepTtmbkSCCjd91EfThVbNYpVQ5ZjdBCXN66CKyJDMJ85HVr5rmXG/nqriTh6cv1l1Js T7AFvvPjUPknS6d+BETMhTkbGzoyS+sywEsQAgA+BMCxBH4LvUmHYhpS+W6CiZ3ZMxjO8Hgc ++w1mLeRUvda3i4/U8wDT3SWuHcB3DWlcppECLkAEQEAAYkBHwQYAQIACQUCVI67igIbDAAK CRBxXD01xc4QCZ4dB/0QrnEasxjM0PGeXK5hcZMT9Eo998alUfn5XU0RQDYdwp6/kMEXMdmT oH0F0xB3SQ8WVSXA9rrc4EBvZruWQ+5/zjVrhhfUAx12CzL4oQ9Ro2k45daYaonKTANYG22y //x8dLe2Fv1By4SKGhmzwH87uXxbTJAUxiWIi1np0z3/RDnoVyfmfbbL1DY7zf2hYXLLzsJR mSsED/1nlJ9Oq5fALdNEPgDyPUerqHxcmIub+pF0AzJoYHK5punqpqfGmqPbjxrJLPJfHVKy goMj5DlBMoYqEgpbwdUYkH6QdizJJCur4icy8GUNbisFYABeoJ91pnD4IGei3MTdvINSZI5e Message-ID: <161e938d-929b-1fdb-ba77-56b839c14b5b@acm.org> Date: Thu, 9 Apr 2020 20:12:21 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: <20200409214530.2413-6-mcgrof@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020-04-09 14:45, Luis Chamberlain wrote: > blk_put_queue() puts decrements the refcount for the request_queue ^^^^ can this word be left out? > diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h > index 8b1cab52cef9..46fee1ef92e3 100644 > --- a/include/linux/blkdev.h > +++ b/include/linux/blkdev.h > @@ -614,6 +614,7 @@ struct request_queue { > #define QUEUE_FLAG_PCI_P2PDMA 25 /* device supports PCI p2p requests */ > #define QUEUE_FLAG_ZONE_RESETALL 26 /* supports Zone Reset All */ > #define QUEUE_FLAG_RQ_ALLOC_TIME 27 /* record rq->alloc_time_ns */ > +#define QUEUE_FLAG_DEFER_REMOVAL 28 /* defer queue removal */ > > #define QUEUE_FLAG_MQ_DEFAULT ((1 << QUEUE_FLAG_IO_STAT) | \ > (1 << QUEUE_FLAG_SAME_COMP)) > @@ -648,6 +649,8 @@ bool blk_queue_flag_test_and_set(unsigned int flag, struct request_queue *q); > #else > #define blk_queue_rq_alloc_time(q) false > #endif > +#define blk_queue_defer_removal(q) \ > + test_bit(QUEUE_FLAG_DEFER_REMOVAL, &(q)->queue_flags) Since blk_queue_defer_removal() has no callers the code that depends on QUEUE_FLAG_DEFER_REMOVAL to be set will be subject to bitrot. It would make me happy if the QUEUE_FLAG_DEFER_REMOVAL flag and the code that depends on that flag would be removed. Please add a might_sleep() call in blk_put_queue() since with this patch applied it is no longer allowed to call blk_put_queue() from atomic context. Thanks, Bart.