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=-8.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 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 80F88C433E0 for ; Thu, 11 Feb 2021 12:07:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5771D64DA1 for ; Thu, 11 Feb 2021 12:07:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230373AbhBKMGr (ORCPT ); Thu, 11 Feb 2021 07:06:47 -0500 Received: from mail.kernel.org ([198.145.29.99]:45532 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230147AbhBKLyl (ORCPT ); Thu, 11 Feb 2021 06:54:41 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9248264E6F; Thu, 11 Feb 2021 11:53:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1613044439; bh=gicVhM+wtkSMREjoHbBuY4IMQqDkvxQMpAmUQL2bdt4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=AkD8I8ftAHIQToJb6OooX5MqichnZBQ8UXr5PjaBmx9wjmdGLu53x9urtnhYcEM/z x61sCP0wQw4L/NQrwMk7gW6dh7uui15R7Y0SOJdZx6D25CW2TO9/8X/6igJ1HRy8bP nF831tJdAk/emaXJS5LD0qy4xYJDTgybrg4nmucIk4z6FDeAFcN6cratVQb7Ylzu4Z lW5RaztVRcenUHI1C/t/pzotbIsW9WmhxIhUakgKPZ826k3D9kD8kqWGJat+kc7XXR SGGx7TzmWEavPQw8qSBCFchk5oMoygCwqIJ5xGFLVmonwuXTY65bXFcJh03lSeQfds S6B6FVKmgev2A== Date: Thu, 11 Feb 2021 11:53:54 +0000 From: Will Deacon To: Anshuman Khandual Cc: Mark Rutland , David Hildenbrand , Catalin Marinas , linux-kernel@vger.kernel.org, Mike Rapoport , linux-mm@kvack.org, =?iso-8859-1?B?Suly9G1l?= Glisse , James Morse , Dan Williams , Robin Murphy , Ard Biesheuvel , linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH V2 1/2] arm64/mm: Fix pfn_valid() for ZONE_DEVICE based memory Message-ID: <20210211115354.GB29894@willie-the-truck> References: <1612239114-28428-1-git-send-email-anshuman.khandual@arm.com> <1612239114-28428-2-git-send-email-anshuman.khandual@arm.com> <20210202123215.GA16868@willie-the-truck> <20210202123524.GB16868@willie-the-truck> <20210202125152.GC16868@willie-the-truck> <4d8f5156-8628-5531-1485-322ad92aa15c@redhat.com> <0e649f28-4d54-319d-f876-8a93870cda7f@arm.com> <20210205185552.GA23216@willie-the-truck> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210205185552.GA23216@willie-the-truck> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Feb 05, 2021 at 06:55:53PM +0000, Will Deacon wrote: > On Wed, Feb 03, 2021 at 09:20:39AM +0530, Anshuman Khandual wrote: > > On 2/2/21 6:26 PM, David Hildenbrand wrote: > > > On 02.02.21 13:51, Will Deacon wrote: > > >> On Tue, Feb 02, 2021 at 01:39:29PM +0100, David Hildenbrand wrote: > > >>> As I expressed already, long term we should really get rid of the arm64 > > >>> variant and rather special-case the generic one. Then we won't go out of > > >>> sync - just as it happened with ZONE_DEVICE handling here. > > >> > > >> Why does this have to be long term? This ZONE_DEVICE stuff could be the > > >> carrot on the stick :) > > > > > > Yes, I suggested to do it now, but Anshuman convinced me that doing a > > > simple fix upfront might be cleaner --- for example when it comes to > > > backporting :) > > > > Right. The current pfn_valid() breaks for ZONE_DEVICE memory and this fixes > > the problem in the present context which can be easily backported if required. > > > > Changing or rather overhauling the generic code with new configs as proposed > > earlier (which I am planning to work on subsequently) would definitely be an > > improvement for the current pfn_valid() situation in terms of maintainability > > but then it should not stop us from fixing the problem now. > > Alright, I've mulled this over a bit. I don't agree that this patch helps > with maintainability (quite the opposite, in fact), but perfection is the > enemy of the good so I'll queue the series for 5.12. However, I'll revert > the changes at the first sign of a problem, so please do work towards a > generic solution which can replace this in the medium term. ... and dropped. These patches appear to be responsible for a boot regression reported by CKI: https://lore.kernel.org/r/cki.8D1CB60FEC.K6NJMEFQPV@redhat.com Will 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=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,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 1636CC433DB for ; Thu, 11 Feb 2021 11:55:24 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id C3F1664EAA for ; Thu, 11 Feb 2021 11:55:23 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C3F1664EAA Authentication-Results: mail.kernel.org; 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Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1lAAY1-0002x4-0s; Thu, 11 Feb 2021 11:54:13 +0000 Received: from mail.kernel.org ([198.145.29.99]) by merlin.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1lAAXr-0002uB-4L for linux-arm-kernel@lists.infradead.org; Thu, 11 Feb 2021 11:54:10 +0000 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9248264E6F; Thu, 11 Feb 2021 11:53:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1613044439; bh=gicVhM+wtkSMREjoHbBuY4IMQqDkvxQMpAmUQL2bdt4=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=AkD8I8ftAHIQToJb6OooX5MqichnZBQ8UXr5PjaBmx9wjmdGLu53x9urtnhYcEM/z x61sCP0wQw4L/NQrwMk7gW6dh7uui15R7Y0SOJdZx6D25CW2TO9/8X/6igJ1HRy8bP nF831tJdAk/emaXJS5LD0qy4xYJDTgybrg4nmucIk4z6FDeAFcN6cratVQb7Ylzu4Z lW5RaztVRcenUHI1C/t/pzotbIsW9WmhxIhUakgKPZ826k3D9kD8kqWGJat+kc7XXR SGGx7TzmWEavPQw8qSBCFchk5oMoygCwqIJ5xGFLVmonwuXTY65bXFcJh03lSeQfds S6B6FVKmgev2A== Date: Thu, 11 Feb 2021 11:53:54 +0000 From: Will Deacon To: Anshuman Khandual Subject: Re: [PATCH V2 1/2] arm64/mm: Fix pfn_valid() for ZONE_DEVICE based memory Message-ID: <20210211115354.GB29894@willie-the-truck> References: <1612239114-28428-1-git-send-email-anshuman.khandual@arm.com> <1612239114-28428-2-git-send-email-anshuman.khandual@arm.com> <20210202123215.GA16868@willie-the-truck> <20210202123524.GB16868@willie-the-truck> <20210202125152.GC16868@willie-the-truck> <4d8f5156-8628-5531-1485-322ad92aa15c@redhat.com> <0e649f28-4d54-319d-f876-8a93870cda7f@arm.com> <20210205185552.GA23216@willie-the-truck> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20210205185552.GA23216@willie-the-truck> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210211_065403_302068_1629A9F7 X-CRM114-Status: GOOD ( 25.13 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Mark Rutland , David Hildenbrand , Catalin Marinas , linux-kernel@vger.kernel.org, Mike Rapoport , linux-mm@kvack.org, =?iso-8859-1?B?Suly9G1l?= Glisse , James Morse , Dan Williams , Robin Murphy , Ard Biesheuvel , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Feb 05, 2021 at 06:55:53PM +0000, Will Deacon wrote: > On Wed, Feb 03, 2021 at 09:20:39AM +0530, Anshuman Khandual wrote: > > On 2/2/21 6:26 PM, David Hildenbrand wrote: > > > On 02.02.21 13:51, Will Deacon wrote: > > >> On Tue, Feb 02, 2021 at 01:39:29PM +0100, David Hildenbrand wrote: > > >>> As I expressed already, long term we should really get rid of the arm64 > > >>> variant and rather special-case the generic one. Then we won't go out of > > >>> sync - just as it happened with ZONE_DEVICE handling here. > > >> > > >> Why does this have to be long term? This ZONE_DEVICE stuff could be the > > >> carrot on the stick :) > > > > > > Yes, I suggested to do it now, but Anshuman convinced me that doing a > > > simple fix upfront might be cleaner --- for example when it comes to > > > backporting :) > > > > Right. The current pfn_valid() breaks for ZONE_DEVICE memory and this fixes > > the problem in the present context which can be easily backported if required. > > > > Changing or rather overhauling the generic code with new configs as proposed > > earlier (which I am planning to work on subsequently) would definitely be an > > improvement for the current pfn_valid() situation in terms of maintainability > > but then it should not stop us from fixing the problem now. > > Alright, I've mulled this over a bit. I don't agree that this patch helps > with maintainability (quite the opposite, in fact), but perfection is the > enemy of the good so I'll queue the series for 5.12. However, I'll revert > the changes at the first sign of a problem, so please do work towards a > generic solution which can replace this in the medium term. ... and dropped. These patches appear to be responsible for a boot regression reported by CKI: https://lore.kernel.org/r/cki.8D1CB60FEC.K6NJMEFQPV@redhat.com Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel