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Tue, 27 Oct 2026 06:35:14 -0400 (EDT) X-Mailer: MessagingEngine.com Webmail Interface X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 X-ThreadId: AUJ1OXWu3nCJ Date: Tue, 27 Oct 2026 11:33:08 +0100 From: "Arnd Bergmann" To: "James Houghton" , "Andrew Morton" , "Alexander Viro" Cc: "Thomas Gleixner" , "Peter Zijlstra" , "Kees Cook" , "David Hildenbrand (Red Hat)" , "Lorenzo Stoakes" , "Liam R. Howlett" , "Vlastimil Babka (SUSE)" , "Mike Rapoport" , "Suren Baghdasaryan" , "Michal Hocko" , "Sean Christopherson" , "Paolo Bonzini" , "Jim Mattson" , "Jens Axboe" , "Pavel Begunkov" , "James E . J . Bottomley" , "Martin K. Petersen" , "David Sterba" , "Chris Mason" , "Alexei Starovoitov" , "Daniel Borkmann" , "John Fastabend" , "Josh Poimboeuf" , "Steven Rostedt" , "Masami Hiramatsu" , "Mathieu Desnoyers" , "Ingo Molnar" , "Arnaldo Carvalho de Melo" , "Namhyung Kim" , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, kvm@vger.kernel.org, io-uring@vger.kernel.org, linux-scsi@vger.kernel.org, linux-btrfs@vger.kernel.org, bpf@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org Message-Id: <3c125ff6-5426-4f19-8e34-fb564d4b6387@app.fastmail.com> In-Reply-To: <14f5f919-55bd-47c6-a1c8-6f1445cce733@app.fastmail.com> References: <20261026215226.3713941-1-jthoughton@google.com> <14f5f919-55bd-47c6-a1c8-6f1445cce733@app.fastmail.com> Subject: Re: [RFC PATCH 00/10] uaccess: Refuse and warn on user accesses when current->mm is NULL Content-Type: text/plain Content-Transfer-Encoding: 7bit On Tue, Oct 27, 2026, at 01:12, Arnd Bergmann wrote: > > E.g. on arm64 with CONFIG_ARM64_SW_TTBR0_PAN, the page table base for > the current process is only set in user_access_begin() and would > not point to any task here. Without ttbr0_pan, it should be > covered by cpu_set_reserved_ttbr0() turning off all user space access > for kernel threads. correction: for non-sw_ttbr0_pan, enter_lazy_tlb() does nothing on arm64, so it is the same as x86 and the others. Arnd