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Howlett" References: <20251113014656.2605447-1-samuel.holland@sifive.com> <20251113014656.2605447-9-samuel.holland@sifive.com> From: "David Hildenbrand (Red Hat)" Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 7EFA2C000B X-Stat-Signature: q7uon7sbaak6cpbuur59tbkywfithwzk X-Rspam-User: X-HE-Tag: 1764265668-938150 X-HE-Meta: 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 lI2+Ch76 V0X1HkCmuYwZTSte28KRH2ngEgjXgPg1tYc5Z+pVho5TLpW5RzzJk+eHjY6RXexUPPIoHHqedGO8GMlsEPSvNVvaACJItz8QKqrLbqVeV8oc1IUHd1UJmuq8m7DpRa9Pr2kBD7PiucXblV84fZVCZ4NalB0nnCtFKm3DVEa6MQhXMXdFHNdGXv7OvRqQGushGgykAqWmdeH+qY4ffJKdoSWWtL3PM6sK8sVR4+kLFeeSxci4bz7XLrSV8oFMrIYNRpkRvtTMqSgRrB3yZeThw8mIHVPtm8KcE5UmXp1c2zdL+QW0M5x75Hk1vcyvB+2PLWaWOEozvKS6931q/8cbDPzh6jY13Fc2QPmEs 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 11/27/25 17:57, Ryan Roberts wrote: > On 13/11/2025 01:45, Samuel Holland wrote: >> Currently, some functions such as pte_offset_map() are passed both >> pointers to hardware page tables, and pointers to previously-read PMD >> entries on the stack. To ensure correctness in the first case, these >> functions must use the page table accessor function (pmdp_get()) to >> dereference the supplied pointer. However, this means pmdp_get() is >> called twice in the second case. This double call must be avoided if >> pmdp_get() applies some non-idempotent transformation to the value. >> >> Avoid the double transformation by calling set_pmd() on the stack >> variables where necessary to keep set_pmd()/pmdp_get() calls balanced. > > I don't think this is a good solution. Agreed, set_pmd(&pmd, pmd); is rather horrible. -- Cheers David