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b=fxgCSlx51Fk9w6LKE73pPGRFcbVnACo3pctojXHqHqz3aUqccWa1r7ZW7mbkZ/vrp RrqubvT3M7YmFzgQgaSQOOfzcxNsOWyW85r4GkrpdUfJOO+nWj5jxJhR/SZRYvzrW3 ffiSBfA7WOyg5BtEDQJ2HAlzcFtfr0s+W/H0uPgqFl9nNVw5jhnoEX7KMTa6AYXkp5 4u9pap0dbIVXzJE9wAIWn+ZEyW0f1Nf+LmylfWX/wU6GwnUY2edAOfTF+szxCgdanI Xk5UtLvWogbI6/OwlmgFmy+dNflrFZsjVRSqvZxTl2wtF7bf6R9VQutQoVQRGVdbLK vwgZuxilUXpHQ== Message-ID: <8c70259a-94ed-415c-89c1-572145c64670@kernel.org> Date: Thu, 17 Sep 2026 17:29:48 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/1] mm/huge_memory: disallow raw PMD mappings of the huge zero page To: Kiryl Shutsemau , Lance Yang Cc: akpm@linux-foundation.org, ziy@nvidia.com, baolin.wang@linux.alibaba.com, liam@infradead.org, nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, usama.arif@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20260917121010.60966-1-lance.yang@linux.dev> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 8E24414000D X-Stat-Signature: sgnjgjqkjqny7q7e5m3zdi3g443oc11e X-Rspam-User: X-HE-Tag: 1789658994-361421 X-HE-Meta: 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 bEGacjRU LjsUIAiV+kB5cSM/2VUj8Bp7vfvdWscUNDZWB0wMn8lR1KgOLiJn4UXMp8hKJvRrMEu39O7in1sWchtIZ0Oelm3HNQ+d0bCTvWeGLMXKa/ITRuC0LICfyUM84dQQcXVUcARZOobCaNsR9y0RBXVRJ3Tr4lpYkpuMjvv5MqpFv6hULjdHE/3QiZPUy1h26tZHFoxYsZJcXs0EXe383xYHA28zt6n9ThgC3J/Gh8vhQuVs5xch2dkKurYBLxkfbJUCChF+N3q227Hh14VbQ3oApa7oP61JhJWujqAIM2dCVaT756jxkoisPVDZuX5n3g4AhnPM/AV15egkUx9Q= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/17/26 16:32, Kiryl Shutsemau wrote: > On Thu, Sep 17, 2026 at 08:10:10PM +0800, Lance Yang wrote: >> vm_mixed_zeropage_allowed() validates zeropage insertion into >> VM_MIXEDMAP VMAs. No in-tree user needs to insert the huge zero page >> through vmf_insert_pfn_pmd(). >> >> Return VM_FAULT_SIGBUS if vmf_insert_pfn_pmd() is asked to map it. >> >> Link: https://lore.kernel.org/linux-mm/f76beaf8-351a-4b22-b362-a945a5e1af6a@kernel.org/ >> Suggested-by: Kiryl Shutsemau >> Suggested-by: David Hildenbrand >> Signed-off-by: Lance Yang > > The patch looks fine, but don't we want to cover the same for non-huge > zero page in vmf_insert_pfn_prot()? Why would the zeropage be a problem in PFNMAP mapping? -- Cheers, David