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Thu, 11 Feb 2021 12:21:53 +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 1lAAyk-0005sP-DB for linux-arm-kernel@lists.infradead.org; Thu, 11 Feb 2021 12:21:51 +0000 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 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-Disposition: inline In-Reply-To: <23e5eb93-a39c-c68e-eac1-c5ccf9036079@arm.com> 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_072150_578709_3CCBD2E8 X-CRM114-Status: GOOD ( 27.93 ) 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 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel