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Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , linux-mm@kvack.org, Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , linux-riscv@lists.infradead.org References: <20260720115741.239657-1-usama.arif@linux.dev> <13ec2603d5cbfdc493939f182b71e5133c26af54.camel@surriel.com> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Usama Arif In-Reply-To: <13ec2603d5cbfdc493939f182b71e5133c26af54.camel@surriel.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 512168000D X-Stat-Signature: f7tfbh5adxuw7kf6jzq15i5k3wz195bu X-Rspam-User: X-HE-Tag: 1784566052-739955 X-HE-Meta: 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 iIvMsPcY Y7qPgAay/uZdyvQwH4hsozpuotUdcJwoyno77enJQzEIpC/f8q57fAQ+oXrUHFBzCQ3zT3ZNB0gvGS5Ud5JOP/hpSNUQ4xalZqzxCRWuXrSW0Ra1bhKgGGZraNHQyN6UvC1EMg0NZwiSs7T5e6zd1/k4ygxqtQPHXNuCQoIr7TwTzJrde2L0Q0lBkD+jmR4nxnA9LulmS7u67OlhoJ2OXLNKCX6SWyYaiX+zl9+ln6eV1fHWprDfl2qh/Qoqinr3C9HJhqScMfR7XREqKClZ+xgEsExRXr9kNSUWNm84k/87oSvqEwbvq6qLf3f0Vjt0rRjgD Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 20/07/2026 16:08, Rik van Riel wrote: > On Mon, 2026-07-20 at 04:57 -0700, Usama Arif wrote: >> On Fri, 17 Jul 2026 13:00:32 -0400 Rik van Riel >> wrote: >> >> >>> >>> mm->context.pmlen is set only through PR_SET_TAGGED_ADDR_CTRL and >>> is stable >>> afterwards, so it can be read without the mmap lock, as it already >>> is from >>> untagged_addr() and mm_untag_mask(). >>> >> >> I think it might not be stable? set_tagged_addr_ctrl() can change it >> repeatedly until a CLONE_VM operation sets MM_CONTEXT_LOCK_PMLEN. > > You're right, ARM tagged addresses seem to work a ah do you mean RISCV here? > little differently from x86 LAM. > > It looks like on ARM with MTE, the top 8 bits of > the virtual address are available as tags, meaning > that address space cannot be used for VMAs. > > For purposes of accessing process memory, this > is a little more stable than LAM, because the > number of bits we need to mask out of the address > is always the same when MTE is in use. > > At least, I think so. Am I overlooking anything? > > I will clean up the changelog like you suggested. >