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 E29FEC43381 for ; Thu, 11 Feb 2021 12:21:51 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 7376964E05 for ; Thu, 11 Feb 2021 12:21:51 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7376964E05 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id EF3FF6B00DC; Thu, 11 Feb 2021 07:21:50 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EA5176B00DD; Thu, 11 Feb 2021 07:21:50 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id DE3F96B00DE; Thu, 11 Feb 2021 07:21:50 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0024.hostedemail.com [216.40.44.24]) by kanga.kvack.org (Postfix) with ESMTP id CB1566B00DC for ; Thu, 11 Feb 2021 07:21:50 -0500 (EST) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 96758824999B for ; Thu, 11 Feb 2021 12:21:50 +0000 (UTC) X-FDA: 77805898380.05.mass45_5a07d8f27618 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin05.hostedemail.com (Postfix) with ESMTP id 7ADD91800E37E for ; Thu, 11 Feb 2021 12:21:50 +0000 (UTC) X-HE-Tag: mass45_5a07d8f27618 X-Filterd-Recvd-Size: 4828 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf09.hostedemail.com (Postfix) with ESMTP for ; Thu, 11 Feb 2021 12:21:49 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id BDE0964E9A; Thu, 11 Feb 2021 12:21:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1613046108; bh=o3YtiUDjeinRUlnclOK4o3qUHnz1oyjiknS7o6mlojU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MovGASDhlPuy0OGL9HveOomvFFWZOx3I4EpxBWaKS6XvXdfrFmfkpoZJeky09CoXk k5jC6nBKAHPNa0YfmIQ4AGEg3XhZkJKUYZ5xS7QphKa9WkvpGGI0z020DzApjnX9Vi fUVZPt2baXxhlqpd4/Dlph55KkomG+0dei+Rd1CFxHhUzHthMYoPgCRD29M6kHCco6 kHzMSY0ICFH2HP6xrtjlyV304n9Y711WMcuV+OoFbMJPxLcnJ0xi5GdWexFn1yF+1z pmj8K8Ho0R6vx73nQRj4/nHI1wAHiNfQPVGKBErgyce58PZ024j5Ddy7zhQVT2lE66 +HBHVpHSyBMYA== Date: Thu, 11 Feb 2021 12:21:43 +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: <20210211122143.GC29894@willie-the-truck> References: <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> <20210211115354.GB29894@willie-the-truck> <23e5eb93-a39c-c68e-eac1-c5ccf9036079@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <23e5eb93-a39c-c68e-eac1-c5ccf9036079@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) 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 Thu, Feb 11, 2021 at 05:40:35PM +0530, Anshuman Khandual wrote: > On 2/11/21 5:23 PM, Will Deacon wrote: > > 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: > > Ahh, boot regression ? These patches only change the behaviour > for non boot memory only. Sure, but this thing is horribly fragile, which is why I was nervous about touching it in the first place ;) > > https://lore.kernel.org/r/cki.8D1CB60FEC.K6NJMEFQPV@redhat.com > > Will look into the logs and see if there is something pointing to > the problem. We don't have a log yet, but I've asked whether earlycon works on the problematic machine (the failure seems to be specific to a certain TX2). Either way, this is too late for 5.12 now. Will