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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> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII 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