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 35A2AC433B4 for ; Sun, 25 Apr 2021 20:43:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 089B861260 for ; Sun, 25 Apr 2021 20:43:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231231AbhDYUnm (ORCPT ); Sun, 25 Apr 2021 16:43:42 -0400 Received: from mail-pf1-f171.google.com ([209.85.210.171]:42941 "EHLO mail-pf1-f171.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230494AbhDYUnm (ORCPT ); Sun, 25 Apr 2021 16:43:42 -0400 Received: by mail-pf1-f171.google.com with SMTP id q2so5641719pfk.9; Sun, 25 Apr 2021 13:43:02 -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=sQEBtvQIiwMUyXs4QG1unv0E1sFViEnCAqrsWxCtU+g=; b=ZFvHU1p05WVt1zPNi+wcv89UjgBJ5ZknFlRF1wZS2ucVs4Ika80JUq+/Ip0qq8IXq1 qpPmfe4XkS0HcMXvB4qzEuMOmNdM+AI/QyBJ8OFBuPHFrU8wcHR0dtjNFfnI9CnqKPkQ vfcsi0awQqBI7e6yxfaL91mibZkQKofAjDeepoonGw2A1dDCUjX90W9hrGOOHaDttlO4 v7YmkLyhP8ZQAgtDKFsQ59oUAk/5mmmJTNWCDbzoqgsrRyMj115Qljx4QH5LjGX9VDZj r6H0Nph3PwcbyP1V+pC5hSP2Afk37vDTm7uhBHd+dyWyjolhjcnQ7gfsAOGs8wkWHZR1 4NgA== X-Gm-Message-State: AOAM530FOSE5yymZASQa7G2ZEhdkPpcEyeUkSu9Img32KloMBoZveZAA AT8X3rftclEShV0m4beS+ic= X-Google-Smtp-Source: ABdhPJyGCX1V73odUcSv4Vn0yEldUPFkSigSfvsOAnWlvGKx/7xu0JVHelSbPHU4PfV2e+fCapwsCA== X-Received: by 2002:a63:2445:: with SMTP id k66mr13791516pgk.62.1619383381997; Sun, 25 Apr 2021 13:43:01 -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 a185sm9417917pfd.70.2021.04.25.13.43.00 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 25 Apr 2021 13:43:01 -0700 (PDT) Subject: Re: [PATCH 8/8] blk-mq: clear stale request in tags->rq[] before freeing one request pool To: Ming Lei , linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, Jens Axboe , linux-block@vger.kernel.org, "Martin K . Petersen" , Christoph Hellwig Cc: Khazhy Kumykov , Shin'ichiro Kawasaki , Hannes Reinecke , John Garry , David Jeffery References: <20210425085753.2617424-1-ming.lei@redhat.com> <20210425085753.2617424-9-ming.lei@redhat.com> From: Bart Van Assche Message-ID: Date: Sun, 25 Apr 2021 13:42:59 -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: <20210425085753.2617424-9-ming.lei@redhat.com> 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 1:57 AM, Ming Lei wrote: > + spin_lock_irqsave(&drv_tags->lock, flags); > + list_for_each_entry(page, &tags->page_list, lru) { > + unsigned long start = (unsigned long)page_address(page); > + unsigned long end = start + order_to_size(page->private); > + int i; > + > + for (i = 0; i < set->queue_depth; i++) { > + struct request *rq = drv_tags->rqs[i]; > + unsigned long rq_addr = (unsigned long)rq; > + > + if (rq_addr >= start && rq_addr < end) { > + WARN_ON_ONCE(refcount_read(&rq->ref) != 0); > + cmpxchg(&drv_tags->rqs[i], rq, NULL); > + } > + } > + } > + spin_unlock_irqrestore(&drv_tags->lock, flags); Using cmpxchg() on set->tags[] is only safe if all other set->tags[] accesses are changed into WRITE_ONCE() or READ_ONCE(). Bart.