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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id 3f1490d57ef6-e8b7af9cd06sm1266310276.30.2025.07.11.11.49.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Jul 2025 11:49:53 -0700 (PDT) Date: Fri, 11 Jul 2025 11:49:37 -0700 (PDT) From: Hugh Dickins To: David Hildenbrand cc: Hugh Dickins , Lance Yang , Oscar Salvador , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, nvdimm@lists.linux.dev, Andrew Morton , Juergen Gross , Stefano Stabellini , Oleksandr Tyshchenko , Dan Williams , Alistair Popple , Matthew Wilcox , Jan Kara , Alexander Viro , Christian Brauner , Zi Yan , Baolin Wang , Lorenzo Stoakes , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Jann Horn , Pedro Falcato , Lance Yang Subject: Re: [PATCH RFC 01/14] mm/memory: drop highest_memmap_pfn sanity check in vm_normal_page() In-Reply-To: <056787ba-eed1-4517-89cd-20c7cc9935dc@redhat.com> Message-ID: <5e439af4-6281-43b2-cbd2-616f5d115fdf@google.com> References: <20250617154345.2494405-1-david@redhat.com> <20250617154345.2494405-2-david@redhat.com> <5e5e8d79-61b1-465d-ab5a-4fa82d401215@redhat.com> <36dd6b12-f683-48a2-8b9c-c8cd0949dfdc@redhat.com> <0b1cb496-4e50-252e-5bcf-74a89a78a8c0@google.com> <056787ba-eed1-4517-89cd-20c7cc9935dc@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspam-User: X-Stat-Signature: y7rdg5qrj7mh8brhdao689n1t4xmemb6 X-Rspamd-Queue-Id: 905D1C0016 X-Rspamd-Server: rspam02 X-HE-Tag: 1752259795-631195 X-HE-Meta: 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 2d1JFwVT a8itaHS+erSAU/PyQnQfrSd3jgtcT/Zpxx436fUjO1VCAChpMH8jlQ/XXhFjquLPd8LQGDNAcguHHKPpbgdoDM6IMCIAx+jTZ0gT6 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: List-Subscribe: List-Unsubscribe: On Fri, 11 Jul 2025, David Hildenbrand wrote: > On 08.07.25 04:52, Hugh Dickins wrote: > > > > Of course it's limited in what it can catch (and won't even get called > > if the present bit was not set - a more complete patch might unify with > > those various "Bad swap" messages). Of course. But it's still useful for > > stopping pfn_to_page() veering off the end of the memmap[] (in some > > configs). > > Right, probably in the configs we both don't care that much about nowadays :) I thought it was the other way round: it's useful for stopping pfn_to_page() veering off the end of the memmap[] if it's a memory model where pfn_to_page() is a simple linear conversion. As with SPARSEMEM_VMEMMAP, which I thought was the favourite nowadays. If you don't care about that one much (does hotplug prevent it?), then you do care about the complex pfn_to_page()s, and we should have worried more when "page++"s got unnecessarily converted to folio_page(folio, i) a year or two back (I'm thinking of in mm/rmap.c, maybe elsewhere). Hugh