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To: Karim Manaouil , npiggin@gmail.com Cc: akpm@linux-foundation.org, mike.kravetz@oracle.com, linux-mm@kvack.org References: From: David Hildenbrand Organization: Red Hat In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 0BD5040010 X-Stat-Signature: osk4b93br9rtcr1yhup1b6dy6pnhnwcn X-Rspam-User: X-HE-Tag: 1685019335-631120 X-HE-Meta: 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 4naYVPiQ 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.003026, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 25.05.23 12:06, Karim Manaouil wrote: > Hi, > > In do_anonymous_page(), a new page is allocated and zeroed, and the > corresponding page struct is initialised (setting flags PageUptodate, > PageSwapBacked, etc. and initialising the various counters). > > Then, set_pte_at() is called directly without calling smp_wmb() to make > the updates above visible on other CPUs. > > This could race with a page table walker. The walker can read the new pte > and try to access the page struct or the page content before the changes > above were made visible. Only after acquiring the page table lock (which the writer first has to release), right? -- Thanks, David / dhildenb