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Howlett" , Nikita Kalyazin , Lorenzo Stoakes , Suren Baghdasaryan , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vlastimil Babka , Muchun Song , Mike Rapoport , Hugh Dickins , Andrew Morton , James Houghton , Michal Hocko , David Hildenbrand , Andrea Arcangeli , Oscar Salvador , Axel Rasmussen , Ujwal Kundur Subject: Re: [PATCH v2 1/4] mm: Introduce vm_uffd_ops API Message-ID: References: <20250627154655.2085903-1-peterx@redhat.com> <20250627154655.2085903-2-peterx@redhat.com> <982f4f94-f0bf-45dd-9003-081b76e57027@lucifer.local> MIME-Version: 1.0 In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 7KPV_jqrGDMUMJn0f9bQF6tlEJDu5wh-4_aaEgZHuKQ_1751492201 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 7ED644000B X-Stat-Signature: 84toqkui7isf8oqo6ggse647xerk96mx X-Rspam-User: X-HE-Tag: 1751492203-804013 X-HE-Meta: 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 QmmWTnFg 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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 Wed, Jul 02, 2025 at 05:24:02PM -0400, Liam R. Howlett wrote: > That's because the entry point is from a function pointer, so [3] won't > help at all. > > It is recreating the situation that existed for the vma through the > vm_ops in mmap, but for uffd. And at a lower level (page tables). I do not > want to relive that experience. > > We are not doing this. It is for the benefit of everyone that we are > not doing this. Is the vma issue about "allowing vma->vm_flags to be modified anywhere" issue? Or is there a pointer to the issue being discussed if not? > > We need to find another way. Could you suggest something? The minimum goal is to allow guest-memfd support minor faults. Thanks, -- Peter Xu