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([36.28.158.221]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-841d70f1ed8sm828385b3a.43.2026.05.26.20.56.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 26 May 2026 20:56:18 -0700 (PDT) From: Xueyuan chen To: akpm@linux-foundation.org, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, x86@kernel.org, catalin.marinas@arm.com, will@kernel.org, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, david@kernel.org, ljs@kernel.org, ziy@nvidia.com, baolin.wang@linux.alibaba.com, ryan.roberts@arm.com, dev.jain@arm.com, lance.yang@linux.dev, yang@os.amperecomputing.com, jannh@google.com, Xueyuan Chen Subject: [RFC PATCH 0/3] make persistent huge zero folio read-only Date: Wed, 27 May 2026 11:56:04 +0800 Message-ID: <20260527035607.14919-1-xueyuan.chen21@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Xueyuan Chen Hi all, This series makes the persistent huge zero folio read-only in the direct map. The motivation comes from Jann Horn's read-only zero page work[1] and the follow-up discussion[2] with Yang Shi. As Jann pointed out, the kernel has had bugs, including security bugs, where pages taken with read-only semantics were later written to. For the huge zero folio, making the direct map read-only turns such writes into faults instead of silently corrupting shared zero contents. The permission change is best effort. If the architecture cannot safely make the direct map read-only, the kernel keeps using the writable persistent huge zero folio. Patch 1 adds the generic support for making the persistent huge zero folio read-only. Patches 2 and 3 add arm64 and x86 support. [1] https://lore.kernel.org/linux-mm/20260508-ro-zeropage-v1-1-9808abc20b49@google.com/ [2] https://lore.kernel.org/linux-mm/CAHbLzkrXXe7r3n3jXgDKtwZhRqj=jDx9E6dLOULohnhBguvi9A@mail.gmail.com/ Xueyuan Chen (3): mm: make persistent huge zero folio read-only arm64/mm: make huge zero folio read-only in linear map x86/mm: make huge zero folio read-only in direct map arch/arm64/Kconfig | 1 + arch/arm64/mm/pageattr.c | 16 ++++++++++++++++ arch/x86/Kconfig | 1 + arch/x86/mm/init.c | 11 +++++++++++ include/linux/huge_mm.h | 5 +++++ mm/Kconfig | 17 +++++++++++++++++ mm/huge_memory.c | 25 ++++++++++++++++++++++++- 7 files changed, 75 insertions(+), 1 deletion(-) -- 2.47.3