From: Will Deacon <will@kernel.org>
To: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: "Mark Rutland" <mark.rutland@arm.com>,
"David Hildenbrand" <david@redhat.com>,
"Catalin Marinas" <catalin.marinas@arm.com>,
linux-kernel@vger.kernel.org,
"Mike Rapoport" <rppt@linux.ibm.com>,
linux-mm@kvack.org, "Jérôme Glisse" <jglisse@redhat.com>,
"James Morse" <james.morse@arm.com>,
"Dan Williams" <dan.j.williams@intel.com>,
"Robin Murphy" <robin.murphy@arm.com>,
"Ard Biesheuvel" <ardb@kernel.org>,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH V2 1/2] arm64/mm: Fix pfn_valid() for ZONE_DEVICE based memory
Date: Thu, 11 Feb 2021 11:53:54 +0000 [thread overview]
Message-ID: <20210211115354.GB29894@willie-the-truck> (raw)
In-Reply-To: <20210205185552.GA23216@willie-the-truck>
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
next prev parent reply other threads:[~2021-02-11 12:07 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-02 4:11 [PATCH V2 0/2] arm64/mm: Fix pfn_valid() for ZONE_DEVICE based memory Anshuman Khandual
2021-02-02 4:11 ` [PATCH V2 1/2] " Anshuman Khandual
2021-02-02 12:32 ` Will Deacon
2021-02-02 12:35 ` Will Deacon
2021-02-02 12:39 ` David Hildenbrand
2021-02-02 12:51 ` Will Deacon
2021-02-02 12:56 ` David Hildenbrand
2021-02-03 3:50 ` Anshuman Khandual
2021-02-05 18:55 ` Will Deacon
2021-02-11 11:53 ` Will Deacon [this message]
2021-02-11 12:10 ` Anshuman Khandual
2021-02-11 12:21 ` Will Deacon
2021-02-11 12:35 ` David Hildenbrand
2021-03-03 19:04 ` Catalin Marinas
2021-03-03 19:24 ` David Hildenbrand
2021-03-03 21:24 ` Will Deacon
2021-03-04 3:31 ` Anshuman Khandual
2021-03-04 8:12 ` David Hildenbrand
2021-03-04 9:36 ` Will Deacon
2021-03-05 4:22 ` Anshuman Khandual
2021-02-02 4:11 ` [PATCH V2 2/2] arm64/mm: Reorganize pfn_valid() Anshuman Khandual
2021-02-02 8:26 ` David Hildenbrand
2021-02-05 18:52 ` [PATCH V2 0/2] arm64/mm: Fix pfn_valid() for ZONE_DEVICE based memory Will Deacon
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