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Mon, 30 Mar 2026 04:15:57 -0700 (PDT) Precedence: bulk X-Mailing-List: rust-for-linux@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Mon, 30 Mar 2026 20:15:55 +0900 Message-Id: Cc: "Danilo Krummrich" , "Alice Ryhl" , "David Airlie" , "Simona Vetter" , "Alistair Popple" , , "John Hubbard" , "Joel Fernandes" , "Timur Tabi" , "Zhi Wang" , "Eliot Courtney" , , , Subject: Re: [PATCH v3] gpu: nova-core: gsp: fix undefined behavior in command queue code From: "Alexandre Courbot" To: "kernel test robot" , "Gary Guo" References: <20260326-cmdq-ub-fix-v3-1-96af2148ca5c@nvidia.com> <202603281331.1ESuqgfz-lkp@intel.com> In-Reply-To: <202603281331.1ESuqgfz-lkp@intel.com> On Sat Mar 28, 2026 at 2:53 PM JST, kernel test robot wrote: > Hi Alexandre, > > kernel test robot noticed the following build errors: > > [auto build test ERROR on dff8302ca1d0e773c90dbeeb05e759f995c95482] > > url: https://github.com/intel-lab-lkp/linux/commits/Alexandre-Courbot/= gpu-nova-core-gsp-fix-undefined-behavior-in-command-queue-code/20260327-003= 216 > base: dff8302ca1d0e773c90dbeeb05e759f995c95482 > patch link: https://lore.kernel.org/r/20260326-cmdq-ub-fix-v3-1-96af21= 48ca5c%40nvidia.com > patch subject: [PATCH v3] gpu: nova-core: gsp: fix undefined behavior in = command queue code > config: x86_64-randconfig-102-20260327 (https://download.01.org/0day-ci/a= rchive/20260328/202603281331.1ESuqgfz-lkp@intel.com/config) > compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0= 227cb60147a26a1eeb4fb06e3b505e9c7261) > rustc: rustc 1.88.0 (6b00bc388 2025-06-23) > reproduce (this is a W=3D1 build): (https://download.01.org/0day-ci/archi= ve/20260328/202603281331.1ESuqgfz-lkp@intel.com/reproduce) > > If you fix the issue in a separate patch/commit (i.e. not just a new vers= ion of > the same patch/commit), kindly add following tags > | Reported-by: kernel test robot > | Closes: https://lore.kernel.org/oe-kbuild-all/202603281331.1ESuqgfz-lkp= @intel.com/ > > All errors (new ones prefixed by >>): > >>> ld.lld: error: undefined symbol: rust_build_error > >>> referenced by build_assert.rs:28 (rust/kernel/build_assert.rs:28) > >>> vmlinux.o:(::alloca= te_command) Been able to reproduce this, but only if I use the 0day compiler (i.e. just taking the `.config` is not enough). Bisected all the pointer projections, and the one that triggers this failure is this line of `driver_write_area`: ptr::project!(mut data, [tx..rx - 1]), ... more precisely, the `rx - 1` bit (no problem if I just use `rx`). This really shouldn't happen because the conditional block we are in has already determined that `rx !=3D 0 ` and `tx > rx`, so the expression should be perfectly safe. I'll keep turning the knobs until I find something that works.