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Fri, 20 Jun 2025 12:50:20 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id wMA/BAxZVWiqLgAAD6G6ig (envelope-from ); Fri, 20 Jun 2025 12:50:20 +0000 Date: Fri, 20 Jun 2025 14:50:18 +0200 From: Oscar Salvador To: David Hildenbrand Cc: 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 Subject: Re: [PATCH RFC 01/14] mm/memory: drop highest_memmap_pfn sanity check in vm_normal_page() Message-ID: References: <20250617154345.2494405-1-david@redhat.com> <20250617154345.2494405-2-david@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250617154345.2494405-2-david@redhat.com> X-Rspam-User: X-Stat-Signature: xw3n7kroo5gya8841149xmt9si96eupf X-Rspamd-Queue-Id: 4E38740009 X-Rspamd-Server: rspam02 X-HE-Tag: 1750423823-544015 X-HE-Meta: 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 MvPnrg+d yx7wAwXBq8oEA+9DJ9AwS9RaLYX5Xuy6T/k/KouhwkpwhsWevPwpqFWduk1kjuKFC7EAC4yAPcBlWYOglqQ1IFPJ90/IfJPDDKG6z9G0hFuI2Ntu2x/g5jRhqHdP09TNUcKaIUwM/gRcNc1wNpmqEuJPUOznnFxLKIVbL18RkkZGX8twBMqJFHeAxcCm5DqEq/PxhbLv0SDBz7zxJJpzxMm/ABBe6nC2xJqx8LXtU4BCGoMlLKq5r6ATersSiRJctGqj+Yy0kuRdfma2wrGwQEN0l50xWlfPDOVoagf7kYNAiNEF+w5k5k7KXA8PkkPVQSD+2f9XmFPP2Bsg= 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 Tue, Jun 17, 2025 at 05:43:32PM +0200, David Hildenbrand wrote: > In 2009, we converted a VM_BUG_ON(!pfn_valid(pfn)) to the current > highest_memmap_pfn sanity check in commit 22b31eec63e5 ("badpage: > vm_normal_page use print_bad_pte"), because highest_memmap_pfn was > readily available. > > Nowadays, this is the last remaining highest_memmap_pfn user, and this > sanity check is not really triggering ... frequently. > > Let's convert it to VM_WARN_ON_ONCE(!pfn_valid(pfn)), so we can > simplify and get rid of highest_memmap_pfn. Checking for > pfn_to_online_page() might be even better, but it would not handle > ZONE_DEVICE properly. > > Do the same in vm_normal_page_pmd(), where we don't even report a > problem at all ... > > What might be better in the future is having a runtime option like > page-table-check to enable such checks dynamically on-demand. Something > for the future. > > Signed-off-by: David Hildenbrand I'm confused, I'm missing something here. Before this change we would return NULL if e.g: pfn > highest_memmap_pfn, but now we just print the warning and call pfn_to_page() anyway. AFAIK, pfn_to_page() doesn't return NULL? -- Oscar Salvador SUSE Labs