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=-6.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 8348FC433B4 for ; Sun, 25 Apr 2021 09:27:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5DC3961209 for ; Sun, 25 Apr 2021 09:27:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229596AbhDYJ22 (ORCPT ); Sun, 25 Apr 2021 05:28:28 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:54847 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229485AbhDYJ21 (ORCPT ); Sun, 25 Apr 2021 05:28:27 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1619342867; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=RjtHhf1h2GPdx4OubhfVpPhMn9ZwNKESK31goEka/aE=; b=cCKzNFY0vR1Ayrcdf8gTmJpAXGnMXZoFjP1jBqVvd1zXZJlX6+gehNcR/CEc1pwBmvt7CL H9ESD1HloEwjgkLsdGW1umEU/DiGdX8yvgyIJqcTIkHJqEataAxxWMlAUrplC5r5OL0djt 2HvZgXb4F9cJoWQOfYbVxbljXjy20Bs= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-273-GqeOQ1fnNlejx8ljXbLlEg-1; Sun, 25 Apr 2021 05:27:43 -0400 X-MC-Unique: GqeOQ1fnNlejx8ljXbLlEg-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3B46610053E7; Sun, 25 Apr 2021 09:27:41 +0000 (UTC) Received: from T590 (ovpn-13-143.pek2.redhat.com [10.72.13.143]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 63BFF5B4A1; Sun, 25 Apr 2021 09:27:31 +0000 (UTC) Date: Sun, 25 Apr 2021 17:27:34 +0800 From: Ming Lei To: linux-nvme@lists.infradead.org, linux-scsi@vger.kernel.org, Jens Axboe , linux-block@vger.kernel.org, "Martin K . Petersen" , Christoph Hellwig Cc: Bart Van Assche , Khazhy Kumykov , Shin'ichiro Kawasaki , Hannes Reinecke , John Garry , David Jeffery Subject: Re: [PATCH 0/8] blk-mq: fix request UAF related with iterating over tagset requests Message-ID: References: <20210425085753.2617424-1-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210425085753.2617424-1-ming.lei@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-scsi@vger.kernel.org On Sun, Apr 25, 2021 at 04:57:45PM +0800, Ming Lei wrote: > Hi Guys, > > Revert 4 patches from Bart which try to fix request UAF issue related > with iterating over tagset wide requests, because: > > 1) request UAF caused by normal completion vs. async completion during > iterating can't be covered[1] > > 2) clearing ->rqs[] is added in fast path, which causes performance loss > by 1% according to Bart's test > > 3) Bart's approach is too complicated, and some changes aren't needed, > such as adding two versions of tagset iteration 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. 5) freeing request pool in updating nr_requests isn't covered. Thanks, Ming