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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7ED91C433EF for ; Tue, 19 Oct 2021 17:54:12 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id EBF7160F57 for ; Tue, 19 Oct 2021 17:54:11 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org EBF7160F57 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ziepe.ca Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 714D5900003; Tue, 19 Oct 2021 13:54:11 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6EB27900002; Tue, 19 Oct 2021 13:54:11 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 56472900003; Tue, 19 Oct 2021 13:54:11 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 49C36900002 for ; Tue, 19 Oct 2021 13:54:11 -0400 (EDT) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 07201181BF8A5 for ; Tue, 19 Oct 2021 17:54:11 +0000 (UTC) X-FDA: 78713935902.30.A131C6E Received: from mail-qt1-f170.google.com (mail-qt1-f170.google.com [209.85.160.170]) by imf09.hostedemail.com (Postfix) with ESMTP id EA346300010C for ; Tue, 19 Oct 2021 17:54:08 +0000 (UTC) Received: by mail-qt1-f170.google.com with SMTP id n2so735282qta.2 for ; Tue, 19 Oct 2021 10:54:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=k4EO566ZbpDs//uEG0jbVR7BFdP1GfXfmKzfi4PdmWw=; b=HB4JP5njikOn5AfAjstCyQb2U7X3CujnisIyXaASRNun6gILVZvON+Yk48mBRHPRQR RY1+sRlgsr4BKrj236S0iTZsTOsNkkZjZ77O+6H/cvjckutVQZ3lo8RY8U232+LTDoYD wrihaSgZz2EistaLinuluW7+Nf7Q1gmULkotO5by0ezt3trLunAM+NZd9jcsJb3f3Wi4 z9wh4z0QqPvbnullfeEX1bvb04TiS8B3jP4X5b6vkUqhm2JFdw/xlnQqiRMTT8tECovZ H5OJfA5xdR7xDlsP6Q3ZnFWs3v7A5Erau3MMcunjF2p/JVcC2lBzQ800djcevSsut0s3 fsqg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=k4EO566ZbpDs//uEG0jbVR7BFdP1GfXfmKzfi4PdmWw=; b=kNj4s/jjUVs1Gi2y6IMWMtCm04aFwTpIKIQAYPF61+o4/dSqp9tP/wSWZ64BPuk5az k7MyPYA0oAbm+F5YFZUkSOBRWee3s8N+9H07Vxc46yn+KkL0L8ZINfYHf8bQIL0CW3jP XTBDqX245yubcG8mjRV7ksDJEwogE/g8KhJhF+Swk9p0zlHZ7sLxrDY3AhHE+2CeW8Lc claNOvH3bPsAn7ACcfTfxFRNmPic9hZYH0lii3IAMkysTcYNpSK9agxZoTqh50QcWSf9 EfgRuBYmU4cwzJMY2UD5K13eC+FROSftpDPLyZlD5CNjjBW7J0wixUtWvuF8hUG5uHpK 1sBQ== X-Gm-Message-State: AOAM531xZwBy4m54HeXMOjY/4Hm0bK8ESoKa8N72iY3ghQd7OCg5zCRh xDay7UjtEhM9R2PgVmz5pkw55w== X-Google-Smtp-Source: ABdhPJz54D+TH75Ir6oqy79nFFUrYbmeO/WH3eSFZrTLNjPikl0roL2ySe8DOGvYpxXiO4sh+slelQ== X-Received: by 2002:ac8:74c7:: with SMTP id j7mr1578684qtr.118.1634666049948; Tue, 19 Oct 2021 10:54:09 -0700 (PDT) Received: from ziepe.ca (hlfxns017vw-142-162-113-129.dhcp-dynamic.fibreop.ns.bellaliant.net. [142.162.113.129]) by smtp.gmail.com with ESMTPSA id u189sm8144732qkh.14.2021.10.19.10.54.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 19 Oct 2021 10:54:09 -0700 (PDT) Received: from jgg by mlx with local (Exim 4.94) (envelope-from ) id 1mctJQ-00GuaZ-PR; Tue, 19 Oct 2021 14:54:08 -0300 Date: Tue, 19 Oct 2021 14:54:08 -0300 From: Jason Gunthorpe To: Dan Williams Cc: Joao Martins , Gerald Schaefer , Christoph Hellwig , Heiko Carstens , Vasily Gorbik , Christian Borntraeger , Linux NVDIMM , linux-s390 , Matthew Wilcox , Alex Sierra , "Kuehling, Felix" , Linux MM , Ralph Campbell , Alistair Popple , Vishal Verma , Dave Jiang Subject: Re: can we finally kill off CONFIG_FS_DAX_LIMITED Message-ID: <20211019175408.GJ3686969@ziepe.ca> References: <20210824202449.19d524b5@thinkpad> <20211014230439.GA3592864@nvidia.com> <5ca908e3-b4ad-dfef-d75f-75073d4165f7@oracle.com> <20211018233045.GQ2744544@nvidia.com> <20211019142032.GT2744544@nvidia.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: EA346300010C X-Stat-Signature: ip6y5kpeo5n4hmjp563w56jx3g5jr9c7 Authentication-Results: imf09.hostedemail.com; dkim=pass header.d=ziepe.ca header.s=google header.b=HB4JP5nj; dmarc=none; spf=pass (imf09.hostedemail.com: domain of jgg@ziepe.ca designates 209.85.160.170 as permitted sender) smtp.mailfrom=jgg@ziepe.ca X-Rspamd-Server: rspam02 X-HE-Tag: 1634666048-800083 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000022, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, Oct 19, 2021 at 10:38:42AM -0700, Dan Williams wrote: > > So we can just delete the detection of the page size and rely on the > > zap code to wipe out the entire level, not split it. Which is what we > > have today already. > > As Joao points out, userspace wants to know the blast radius of the > unmap for historical reasons. I do think it's worth deprecating that > somehow... providing a better error management interface is part of > the DAX-reflink enabling. OK, it makes sense. I have a less invasive idea though - emulate what zap is doing: if (!pud_present(*pud)) return 0; if (pud_leaf(*pud)) return PUD_SHIFT; if (!pmd_present(*pud)) return 0; if (pmd_leaf(*pud)) return PMD_SHIFT; return PAGE_SHIFT; Which would return the "blast radius" of the unmap_mapping_range() when it rounds up to the left page level that contains the VA. Now it doesn't need the pte_devmap test.. And when both DAX's learn to use compound_head this can be deleted. Jason