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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham 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 D496DECE560 for ; Mon, 24 Sep 2018 15:58:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8CB9220883 for ; Mon, 24 Sep 2018 15:58:45 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8CB9220883 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=acm.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731120AbeIXWBd (ORCPT ); Mon, 24 Sep 2018 18:01:33 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:38675 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730257AbeIXWBd (ORCPT ); Mon, 24 Sep 2018 18:01:33 -0400 Received: by mail-pg1-f195.google.com with SMTP id r77-v6so4220789pgr.5; Mon, 24 Sep 2018 08:58:43 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:message-id:subject:from:to:cc:date:in-reply-to :references:mime-version:content-transfer-encoding; bh=mw36CrvfVrpxzIqWOBQZfvvkpequs5zfefy49OeARZ4=; b=ctQkeY/lrPnK1tVBhY6SC9UZUVOn2COWn6LsMxu3DEmBHV/nvlxsFtCxxJCi82Biry H1yLzZ4CAGrtYrtXx4usLo/ykBTkHFaS7+S4vdAIEqEBQ42aLWeDTY/nvfWRhOwlmFsL ORx8K3kMTlFszRLBtkcvVGChgU7rsIaydHbFqH2nz0kw9itsNokUHgwiNK/0gAPrZzA+ ZCKXjRPv7fddF8VRjq8CoONiF7OCF1dlHEdDdZzHfWzy78DOjQRi7mM9X+aAq+pXUvVA dQN5v0s/V30eb0T/NO2pGyqxwfPwh00Wv1phUirZH+KBuIpARcUa65kWc4ZhKLNZEaQx 8y8w== X-Gm-Message-State: ABuFfogkU3BLnqejVfzRokbndGQRCWpxPZGzz8Rr45ViWJMByeR+KT3n 4cXo71x+KjWLydksIzrH6R4= X-Google-Smtp-Source: ACcGV61eeotsNE97O6u9qYBCZdAZB8q0HP2yuUnXqihmrReseS3H/c32dI6QsT836BLCBTOCZuAptw== X-Received: by 2002:a63:9809:: with SMTP id q9-v6mr9996689pgd.58.1537804722899; Mon, 24 Sep 2018 08:58:42 -0700 (PDT) Received: from ?IPv6:2620:15c:2cd:203:5cdc:422c:7b28:ebb5? ([2620:15c:2cd:203:5cdc:422c:7b28:ebb5]) by smtp.gmail.com with ESMTPSA id w12-v6sm55026294pfd.110.2018.09.24.08.58.41 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 24 Sep 2018 08:58:42 -0700 (PDT) Message-ID: <1537804720.195115.9.camel@acm.org> Subject: Re: block: DMA alignment of IO buffer allocated from slab From: Bart Van Assche To: Andrey Ryabinin , Ming Lei , Vitaly Kuznetsov Cc: Christoph Hellwig , Ming Lei , linux-block , linux-mm , Linux FS Devel , "open list:XFS FILESYSTEM" , Dave Chinner , Linux Kernel Mailing List , Jens Axboe , Christoph Lameter , Linus Torvalds , Greg Kroah-Hartman Date: Mon, 24 Sep 2018 08:58:40 -0700 In-Reply-To: References: <20180920063129.GB12913@lst.de> <87h8ij0zot.fsf@vitty.brq.redhat.com> <20180923224206.GA13618@ming.t460p> <38c03920-0fd0-0a39-2a6e-70cd8cb4ef34@virtuozzo.com> <20a20568-5089-541d-3cee-546e549a0bc8@acm.org> <12eee877-affa-c822-c9d5-fda3aa0a50da@virtuozzo.com> <1537801706.195115.7.camel@acm.org> Content-Type: text/plain; charset="UTF-7" X-Mailer: Evolution 3.26.2-1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 2018-09-24 at 18:52 +-0300, Andrey Ryabinin wrote: +AD4 Yes, with CONFIG+AF8-DEBUG+AF8-SLAB+AD0-y, CONFIG+AF8-SLUB+AF8-DEBUG+AF8-ON+AD0-y kmalloc() guarantees +AD4 that result is aligned on ARCH+AF8-KMALLOC+AF8-MINALIGN boundary. Had you noticed that Vitaly Kuznetsov showed that this is not the case? See also https://lore.kernel.org/lkml/87h8ij0zot.fsf+AEA-vitty.brq.redhat.com/. Thanks, Bart.