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 1282DC3A5A4 for ; Wed, 4 Sep 2019 05:19:40 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D384C2073F for ; Wed, 4 Sep 2019 05:19:39 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D384C2073F Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5D2F66B0003; Wed, 4 Sep 2019 01:19:39 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 584056B0006; Wed, 4 Sep 2019 01:19:39 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4C1E36B0007; Wed, 4 Sep 2019 01:19:39 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0059.hostedemail.com [216.40.44.59]) by kanga.kvack.org (Postfix) with ESMTP id 2B4746B0003 for ; Wed, 4 Sep 2019 01:19:39 -0400 (EDT) Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id BD783824CA39 for ; Wed, 4 Sep 2019 05:19:38 +0000 (UTC) X-FDA: 75896085636.15.taste62_370b306354038 X-HE-Tag: taste62_370b306354038 X-Filterd-Recvd-Size: 2670 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by imf27.hostedemail.com (Postfix) with ESMTP for ; Wed, 4 Sep 2019 05:19:38 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id 7B64868AEF; Wed, 4 Sep 2019 07:19:33 +0200 (CEST) Date: Wed, 4 Sep 2019 07:19:33 +0200 From: Christoph Hellwig To: Matthew Wilcox Cc: Christopher Lameter , Michal Hocko , Vlastimil Babka , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Pekka Enberg , David Rientjes , Ming Lei , Dave Chinner , "Darrick J . Wong" , Christoph Hellwig , 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: <20190904051933.GA10218@lst.de> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190903205312.GK29434@bombadil.infradead.org> User-Agent: Mutt/1.5.17 (2007-11-01) 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 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. But other cases where alignment and not just not crossing a page boundary occurred and we had problems with those before. It just too a long time for people to root cause them.