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b=YqT6uRgQeiMgV6LaXGJpu+ONELl49SC1EESjimSweN54pm/XOyeUMK3m8LaD1GWMo LqyirD+d0LA4s8Sf59sVojGYlYUx+kuWYJtcKuhpTxJuScImz54+YifA+yrUPoCb73 yS8wkF9qtOED4THBT5voqlNs/EzTm7dlaBBimJmnNp8ZIvu/8d1RVlSEl+R8KMrfq2 9WGb+aOyqTYy9sE0DJWFIgLnFRZtaq+L1vzivbh7tvKMpjLedrUQguWpjf6TjvEJuy 3LlTyJxkrH7CM9wVks8DBi282OwhAGAdDxtnoN9yHOoD2gsAw4QtIoPPQ4BtzAPyDD 8t0UkHsCtZLxQ== From: SeongJae Park To: "Kiryl Shutsemau (Meta)" Cc: SeongJae Park , akpm@linux-foundation.org, rppt@kernel.org, peterx@redhat.com, david@kernel.org, ljs@kernel.org, surenb@google.com, vbabka@kernel.org, Liam.Howlett@oracle.com, ziy@nvidia.com, corbet@lwn.net, skhan@linuxfoundation.org, seanjc@google.com, pbonzini@redhat.com, jthoughton@google.com, aarcange@redhat.com, usama.arif@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-kselftest@vger.kernel.org, kvm@vger.kernel.org, kernel-team@meta.com Subject: Re: [PATCH 01/14] mm: decouple protnone helpers from CONFIG_NUMA_BALANCING Date: Wed, 29 Apr 2026 21:47:02 -0700 Message-ID: <20260430044703.77862-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260427114607.4068647-2-kas@kernel.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 5E831120002 X-Stat-Signature: s3j6qsjbauq8ddtpx3cm918pzm8qio96 X-HE-Tag: 1777524433-545966 X-HE-Meta: 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 C0siKhuX CdScATA4ZJtFRpCOdYyTxO7dsyiZXGcRDIJUo8S/MdniChTEDW5U2z+WQgKriWrMJcAZFd2FV/NCVI009WCoMhrB9mUElzPHA0AT+o0+xqzzlRTZKx/RgOAeyY/QXHbF3DcauuP6IHI/hQDP2qSIRzfRVxmTPy49Y5xDDvBc+FYsxBr6PPMaCg5Nm9PBBK/l46IZD3TnunhNd5vaBh74ompYflHGLIuC4/jlU/EyKqfT1612eKtubceVYJVYeqRUWAki9fS9HhLYZukSdnw38DLwklNzrw9EiPZMMDbfr8hsvWhYGO9LNaO2PGw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 27 Apr 2026 12:45:49 +0100 "Kiryl Shutsemau (Meta)" wrote: > pte_protnone() and pmd_protnone() detect present-but-inaccessible page > table entries. This capability is useful beyond NUMA balancing — for > example, userfaultfd working set tracking uses protnone PTEs to track > page access without unmapping pages. I agree. It can be useful for general access monitoring. I'm also slowly but continuously working [1] to use that for DAMON. > > Introduce CONFIG_ARCH_HAS_PTE_PROTNONE to decouple the protnone PTE > infrastructure from CONFIG_NUMA_BALANCING. The six architectures that > support protnone PTEs (x86_64, arm64, powerpc, s390, riscv, loongarch) > now select this option, and CONFIG_NUMA_BALANCING depends on it. > > No functional change — the same set of architectures continues to have > working protnone support, but the infrastructure is now available > independently of NUMA balancing. I think this is a good change for making the infrastructure available for uffd. I believe this can also be useful for making it further available for general access monitoring purposes. I hope this to be landed on the mainline sooner than later. Thank you for doing this, Kiryl! > > Signed-off-by: Kiryl Shutsemau (Meta) > Assisted-by: Claude:claude-opus-4-6 Acked-by: SeongJae Park [1] https://lore.kernel.org/linux-mm/20260218054320.4570-1-sj@kernel.org/ Thanks, SJ [...]