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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 D64F7C433B4 for ; Mon, 26 Apr 2021 01:57:26 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AEF83611ED for ; Mon, 26 Apr 2021 01:57:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231530AbhDZB6F (ORCPT ); Sun, 25 Apr 2021 21:58:05 -0400 Received: from mail-pl1-f173.google.com ([209.85.214.173]:44567 "EHLO mail-pl1-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231403AbhDZB6F (ORCPT ); Sun, 25 Apr 2021 21:58:05 -0400 Received: by mail-pl1-f173.google.com with SMTP id y1so12431347plg.11; Sun, 25 Apr 2021 18:57:25 -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:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=6HEg/Ddsftly7/3yRUEs2qLA5+xUFCZApQad+9OPs/Y=; b=dgTfbANYAETMhHte/tVV0jgbszjbSsOhB/vzJUYELcOM1WQSk5rlGR9Zns8NauyMM/ KAe+NTMIFxnNNfNQ1URvdPC2DrhYP665U2903sB1799PqKLvotmjaCnWuT2B/SNfMilb KRl62kZAfHL1pF63WDdmcH2imMEfVB0TTK6mceNDlP883MDG1LSSGMx2T1+GtAkiasgd Fae7kII+hzY8g1DTLhAGafiE20M+gqPJdDdQMqg7+WVCqXeFHloL0bhXjYmKkeA+w73b gOPvA+I9fEHpEVNbWqScNsd3f0jkUmkfZkSNmfDCa6LFgp5CiP5HlnhWquwOg2cnfsNx Tlvg== X-Gm-Message-State: AOAM532OURgxh02Rh+UNrnXHGks8xO6Byhx37J+vYrajlpF9OdCSnv5e XGSrYk+QzbMprht+zCRUUGU= X-Google-Smtp-Source: ABdhPJyZilykJIV4HMDyE83hi7h3BZxEs7dCPfJYWuizazoZ0MILumlUOVaQeM72OAnEpff7bvNQag== X-Received: by 2002:a17:90a:cf8d:: with SMTP id i13mr11564066pju.53.1619402244598; Sun, 25 Apr 2021 18:57:24 -0700 (PDT) Received: from [192.168.3.219] (c-73-241-217-19.hsd1.ca.comcast.net. [73.241.217.19]) by smtp.gmail.com with ESMTPSA id b21sm10719230pji.39.2021.04.25.18.57.23 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 25 Apr 2021 18:57:23 -0700 (PDT) Subject: Re: [PATCH 0/8] blk-mq: fix request UAF related with iterating over tagset requests To: Ming Lei Cc: linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, Jens Axboe , linux-block@vger.kernel.org, "Martin K . Petersen" , Christoph Hellwig , Khazhy Kumykov , Shin'ichiro Kawasaki , Hannes Reinecke , John Garry , David Jeffery References: <20210425085753.2617424-1-ming.lei@redhat.com> <5c1ef3ec-dd6a-4992-586b-6e67bcd1a678@acm.org> From: Bart Van Assche Message-ID: <56ae9ca8-4e17-0d82-8ff2-08973e1f4693@acm.org> Date: Sun, 25 Apr 2021 18:57:22 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.9.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 4/25/21 6:19 PM, Ming Lei wrote: > On Sun, Apr 25, 2021 at 01:53:16PM -0700, Bart Van Assche wrote: >> On 4/25/21 2:27 AM, Ming Lei wrote: >>> 4) synchronize_rcu() is added before shutting down one request queue, >>> which may slow down reboot/poweroff very much on big systems with lots of >>> HBAs in which lots of LUNs are attached. >> >> The synchronize_rcu() can be removed by using a semaphore >> () instead of an RCU reader lock inside bt_tags_iter(). > > I am not sure you can, because some iteration is done in atomic context. I meant . The functions like read_lock_irq() that are declared in that header file are appropriate for atomic context. Bart.