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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A20E1C25B0E for ; Fri, 12 Aug 2022 14:48:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238061AbiHLOs3 (ORCPT ); Fri, 12 Aug 2022 10:48:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40956 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237826AbiHLOs1 (ORCPT ); Fri, 12 Aug 2022 10:48:27 -0400 Received: from mail-pg1-x52a.google.com (mail-pg1-x52a.google.com [IPv6:2607:f8b0:4864:20::52a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2E497ABD4A for ; Fri, 12 Aug 2022 07:48:25 -0700 (PDT) Received: by mail-pg1-x52a.google.com with SMTP id 24so971909pgr.7 for ; Fri, 12 Aug 2022 07:48:25 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance-com.20210112.gappssmtp.com; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc; bh=tmJm+SpCPyDqJ1lshIA1ETszu0sVt5hUjFD5g/2kg50=; b=aJ+9o9HQcipIlVWgIit02PLYCSWZQby4S9kcexl1KVoRbd5IYGKzIN29a15kXcl3tH kQLYYNSlzNAl1v02d7rPkfua47JAO3GOBNKFzUxavCTsZEeK1OYRR3BdVs4jJNmVoAoH kNPqKF4KotAOzRhuCPRWLuFYoYVXZBp8OpCvop4KzhGmsXmUsZJNDBb316UO1IPRE2PV o9sLm46JHvpK9rCWnkoSbovI/tG5xatcI24KnR2pt8q6nKRhLBxTbVHhauUr4NBYONjI LI3kHQ//6JXOfOrrskh9QahS+X8WZUrfsr3TJ76YFK3ff1+5HijxA00HyJ/6XB/wd4ut gYLg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc; bh=tmJm+SpCPyDqJ1lshIA1ETszu0sVt5hUjFD5g/2kg50=; b=C57lbcjof1KEWJv96yW/jhjPi5edBDW4UqHNc80M7UUZVzsHgi49HJ85AMtWqtj6I9 sCRElP+4PB9NYSsFeKKD5MGt2dtQrpwH+7hd6AnqTj9A0M7UGTO+MtkNlWOrDD2pOkoh pZ223+V+0VXlNo9wBV/XarN8xjAIiQbGLxIrLrN0f6TLI86+kLQ/JkOH1g5froVpP+M8 k9WVpEpaP63Nrs0yLP/waUIBNTaYdMXoZgezmAey3hZAQlweEMkOSZaOo/4B9rxRBkbI m9rXGCZTehG5nfZgz0+KmRNo2nkhunbPJW0F5tgJDUhd7/Bre3nddVWgFVr4FKB6N9S7 S+Zg== X-Gm-Message-State: ACgBeo1La6astXdhadeKmJSjoZ2hBKYgRBPM+dVFMIidz3DwD+OWheQQ o83f6MNpgRGlD9tyYFaEZJ54NYZWcRJPxg== X-Google-Smtp-Source: AA6agR6GZCf3r5KmUJM1S3uTXeEKj1oUGGU+qcmom++g7ekrhliqaeUv0A+Xqdt1Ba4yqQaLzwQyZw== X-Received: by 2002:a63:2dc5:0:b0:423:1abf:d0b3 with SMTP id t188-20020a632dc5000000b004231abfd0b3mr28018pgt.211.1660315704696; Fri, 12 Aug 2022 07:48:24 -0700 (PDT) Received: from [10.4.217.209] ([139.177.225.231]) by smtp.gmail.com with ESMTPSA id u13-20020a170903124d00b0016db6bd77f4sm1898601plh.117.2022.08.12.07.48.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 12 Aug 2022 07:48:24 -0700 (PDT) Message-ID: <686b645c-c4e1-357f-7c57-b961a1feeda0@bytedance.com> Date: Fri, 12 Aug 2022 22:48:20 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.1.0 Subject: Re: [PATCH] blk-mq: move bio merge attempt to blk_mq_submit_bio() Content-Language: en-US To: Jens Axboe Cc: linux-block@vger.kernel.org, linux-kernel@vger.kernel.org References: <20220812083944.79616-1-zhouchengming@bytedance.com> <330468da-a778-6cfc-ce46-a62566d71c8d@kernel.dk> From: Chengming Zhou In-Reply-To: <330468da-a778-6cfc-ce46-a62566d71c8d@kernel.dk> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022/8/12 20:40, Jens Axboe wrote: > On 8/12/22 2:39 AM, Chengming Zhou wrote: >> We will try to get request from cache before alloc request, in >> both cases will first attempt bio merge. >> >> This patch move this common part to blk_mq_submit_bio(), which >> simplify the code and avoid passing in the pointer of bio. > > I don't think this will work. If we get a cached request, then we > know we have a reference to the queue. If you swap these around, > then that's no longer the case and we can have a use-after-free if > the queue goes away. > Sorry, thanks for your reply!