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 76944C3A5A9 for ; Wed, 4 Sep 2019 06:41:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5942C2339E for ; Wed, 4 Sep 2019 06:41:03 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728547AbfIDGlA (ORCPT ); Wed, 4 Sep 2019 02:41:00 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54784 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726004AbfIDGlA (ORCPT ); Wed, 4 Sep 2019 02:41:00 -0400 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9D48E315C006; Wed, 4 Sep 2019 06:40:59 +0000 (UTC) Received: from ming.t460p (ovpn-8-23.pek2.redhat.com [10.72.8.23]) by smtp.corp.redhat.com (Postfix) with ESMTPS id C585C60BFB; Wed, 4 Sep 2019 06:40:48 +0000 (UTC) Date: Wed, 4 Sep 2019 14:40:44 +0800 From: Ming Lei To: Christoph Hellwig Cc: Matthew Wilcox , Christopher Lameter , Michal Hocko , Vlastimil Babka , 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 Subject: Re: [PATCH v2 2/2] mm, sl[aou]b: guarantee natural alignment for kmalloc(power-of-two) Message-ID: <20190904064043.GA7578@ming.t460p> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190904051933.GA10218@lst.de> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Wed, 04 Sep 2019 06:41:00 +0000 (UTC) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org 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? Thanks, Ming