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(p200300cbc708de00549ee4e498dfff72.dip0.t-ipconnect.de. [2003:cb:c708:de00:549e:e4e4:98df:ff72]) by smtp.gmail.com with ESMTPSA id v188-20020a1cacc5000000b00384b71a50d5sm1507806wme.24.2022.03.22.02.46.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 22 Mar 2022 02:46:40 -0700 (PDT) Message-ID: <10851f31-632c-5fb4-a941-3dccc46e5156@redhat.com> Date: Tue, 22 Mar 2022 10:46:38 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.6.2 Subject: Re: [PATCH v1 4/7] arm64/pgtable: support __HAVE_ARCH_PTE_SWP_EXCLUSIVE To: Catalin Marinas , Will Deacon Cc: linux-kernel@vger.kernel.org, Andrew Morton , Hugh Dickins , Linus Torvalds , David Rientjes , Shakeel Butt , John Hubbard , Jason Gunthorpe , Mike Kravetz , Mike Rapoport , Yang Shi , "Kirill A . Shutemov" , Matthew Wilcox , Vlastimil Babka , Jann Horn , Michal Hocko , Nadav Amit , Rik van Riel , Roman Gushchin , Andrea Arcangeli , Peter Xu , Donald Dutile , Christoph Hellwig , Oleg Nesterov , Jan Kara , Liang Zhang , Pedro Gomes , Oded Gabbay , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , linux-mm@kvack.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org References: <20220315141837.137118-1-david@redhat.com> <20220315141837.137118-5-david@redhat.com> <20220321143802.GC11145@willie-the-truck> <20220321174404.GA11389@willie-the-truck> From: David Hildenbrand Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: E3B51180004 X-Stat-Signature: uahyrw7efjerk7t48rqqa6ww8o6rn6aq X-Rspam-User: Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b=R1ySavt5; spf=none (imf06.hostedemail.com: domain of david@redhat.com has no SPF policy when checking 170.10.133.124) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com X-HE-Tag: 1647942403-187429 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 21.03.22 19:27, Catalin Marinas wrote: > On Mon, Mar 21, 2022 at 05:44:05PM +0000, Will Deacon wrote: >> On Mon, Mar 21, 2022 at 04:07:48PM +0100, David Hildenbrand wrote: >>> So the example you gave cannot possibly have that bit set. From what I >>> understand, it should be fine. But I have no real preference: I can also >>> just stick to the original patch, whatever you prefer. >> >> I think I'd prefer to stay on the safe side and stick with bit 2 as you >> originally proposed. If we need to support crazy numbers of swapfiles >> in future then we can revisit the idea of allocating bit 1. > > Sounds fine to me. David, feel free to keep my reviewed-by on the > original patch. > Thanks both, I'll add the following comment to the patch: "Note that we might be able to reuse bit 1, but reusing bit 1 turned out problematic in the past for PROT_NONE handling; so let's play safe and use another bit." -- Thanks, David / dhildenb