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Wed, 25 Jun 2025 07:54:58 +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 5MYqL1KrW2gjEwAAD6G6ig (envelope-from ); Wed, 25 Jun 2025 07:54:58 +0000 Date: Wed, 25 Jun 2025 09:54:57 +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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spamd-Result: default: False [-4.30 / 50.00]; BAYES_HAM(-3.00)[99.99%]; NEURAL_HAM_LONG(-1.00)[-1.000]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MISSING_XM_UA(0.00)[]; MIME_TRACE(0.00)[0:+]; RCPT_COUNT_TWELVE(0.00)[29]; ARC_NA(0.00)[]; TO_DN_SOME(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; RCVD_TLS_ALL(0.00)[]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; R_RATELIMIT(0.00)[to_ip_from(RLhwqoz3wsm4df3nfubx4grhps)]; RCVD_COUNT_TWO(0.00)[2]; FUZZY_BLOCKED(0.00)[rspamd.com]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[localhost.localdomain:mid] X-Spam-Level: X-Spam-Flag: NO X-Spam-Score: -4.30 On Mon, Jun 23, 2025 at 04:04:01PM +0200, David Hildenbrand wrote: > Hi Oscar, Hi David, > > > 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? > > You're missing that vm_normal_page_pmd() was created as a copy from > vm_normal_page() [history of the sanity check above], but as we don't have > (and shouldn't have ...) print_bad_pmd(), we made the code look like this > would be something that can just happen. Ok I see. > > " > Do the same in vm_normal_page_pmd(), where we don't even report a > problem at all ... > " > > So we made something that should never happen a runtime sanity check without > ever reporting a problem ... all clear now, thanks :-) -- Oscar Salvador SUSE Labs