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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 2EC5BC3A5A8 for ; Wed, 4 Sep 2019 07:20:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 77C802339E for ; Wed, 4 Sep 2019 07:20:13 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 77C802339E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 10BA36B0006; Wed, 4 Sep 2019 03:20:09 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 0E2786B0007; Wed, 4 Sep 2019 03:20:09 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id EEC186B0008; Wed, 4 Sep 2019 03:20:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0108.hostedemail.com [216.40.44.108]) by kanga.kvack.org (Postfix) with ESMTP id CD51D6B0006 for ; Wed, 4 Sep 2019 03:20:08 -0400 (EDT) Received: from smtpin01.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id 62919824CA30 for ; Wed, 4 Sep 2019 07:20:08 +0000 (UTC) X-FDA: 75896389296.01.bag76_58695bc48542c X-HE-Tag: bag76_58695bc48542c X-Filterd-Recvd-Size: 7685 Received: from mx1.suse.de (mx2.suse.de [195.135.220.15]) by imf34.hostedemail.com (Postfix) with ESMTP for ; Wed, 4 Sep 2019 07:20:07 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 0DD84B69D; Wed, 4 Sep 2019 07:20:05 +0000 (UTC) Subject: Re: [PATCH v2 2/2] mm, sl[aou]b: guarantee natural alignment for kmalloc(power-of-two) To: Ming Lei , Christoph Hellwig Cc: Matthew Wilcox , Christopher Lameter , Michal Hocko , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Pekka Enberg , David Rientjes , Dave Chinner , "Darrick J . Wong" , linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, James Bottomley , linux-btrfs@vger.kernel.org References: <20190826111627.7505-1-vbabka@suse.cz> <20190826111627.7505-3-vbabka@suse.cz> <0100016cd98bb2c1-a2af7539-706f-47ba-a68e-5f6a91f2f495-000000@email.amazonses.com> <20190828194607.GB6590@bombadil.infradead.org> <20190829073921.GA21880@dhcp22.suse.cz> <0100016ce39e6bb9-ad20e033-f3f4-4e6d-85d6-87e7d07823ae-000000@email.amazonses.com> <20190901005205.GA2431@bombadil.infradead.org> <0100016cf8c3033d-bbcc9ba3-2d59-4654-a7c2-8ba094f8a7de-000000@email.amazonses.com> <20190903205312.GK29434@bombadil.infradead.org> <20190904051933.GA10218@lst.de> <20190904064043.GA7578@ming.t460p> From: Vlastimil Babka Openpgp: preference=signencrypt Autocrypt: addr=vbabka@suse.cz; prefer-encrypt=mutual; keydata= mQINBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 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2ijoaMFTAU+uBtE14UP5F+LWdmRdEGS1Ah1NwooL27uAFllTDQxDhg/+LJ/TqB8ZuidOIy1B xVKRSg3I2m+DUTVqBy7Lixo73hnW69kSjtqCeamY/NSu6LNP+b0wAOKhwz9hBEwEHLp05+mj 5ZFJyfGsOiNUcMoO/17FO4EBxSDP3FDLllpuzlFD7SXkfJaMWYmXIlO0jLzdfwfcnDzBbPwO hBM8hvtsyq8lq8vJOxv6XD6xcTtj5Az8t2JjdUX6SF9hxJpwhBU0wrCoGDkWp4Bbv6jnF7zP Nzftr4l8RuJoywDIiJpdaNpSlXKpj/K6KrnyAI/joYc7 Message-ID: <54e82c0d-aedc-3976-4b29-4f669ac59cae@suse.cz> Date: Wed, 4 Sep 2019 09:20:03 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <20190904064043.GA7578@ming.t460p> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 9/4/19 8:40 AM, Ming Lei wrote: > On Wed, Sep 04, 2019 at 07:19:33AM +0200, Christoph Hellwig wrote: >> On Tue, Sep 03, 2019 at 01:53:12PM -0700, Matthew Wilcox wrote: >>>> Its enabled in all full debug session as far as I know. Fedora for >>>> example has been running this for ages to find breakage in device drivers >>>> etc etc. >>> >>> Are you telling me nobody uses the ramdisk driver on fedora? Because >>> that's one of the affected drivers. >> >> For pmem/brd misaligned memory alone doesn't seem to be the problem. >> Misaligned memory that cross a page barrier is. And at least XFS >> before my log recovery changes only used kmalloc for smaller than >> page size allocation, so this case probably didn't hit. > > BTW, does sl[aou]b guarantee that smaller than page size allocation via kmalloc() > won't cross page boundary any time? AFAIK no, it's the same as with the alignment. After this patch, that guarantee would follow from the alignment one for power of two sizes, but sizes 96 and 192 could still cross page boundary. > Thanks, > Ming >