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Thu, 03 Jul 2025 07:50:22 -0700 (PDT) MIME-Version: 1.0 References: <20250617154345.2494405-1-david@redhat.com> <20250617154345.2494405-2-david@redhat.com> In-Reply-To: <20250617154345.2494405-2-david@redhat.com> From: Lance Yang Date: Thu, 3 Jul 2025 22:50:09 +0800 X-Gm-Features: Ac12FXy9pobZ-Tyl0lhkLRCeovsWyWwet9l7NdvI0FrXp3EdnqPiHRcREj1ytcE Message-ID: Subject: Re: [PATCH RFC 01/14] mm/memory: drop highest_memmap_pfn sanity check in vm_normal_page() 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 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 6CEA810000A X-Stat-Signature: 948wmc1c8rmdfjn3moxu6e641cbz3nt9 X-HE-Tag: 1751554223-55770 X-HE-Meta: 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 /UyXuKxA 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 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 11:44=E2=80=AFPM 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 LGTM. Feel free to add: Reviewed-by: Lance Yang Thanks, Lance