On 6/27/25 2:18 PM, Michael S. Tsirkin wrote: > On Fri, Jun 27, 2025 at 12:28:00PM +0200, Paolo Abeni wrote: >> On 6/27/25 8:41 AM, kernel test robot wrote: >>> kernel test robot noticed the following build warnings: >>> >>> [auto build test WARNING on net-next/main] >>> >>> url: https://github.com/intel-lab-lkp/linux/commits/Paolo-Abeni/scripts-kernel_doc-py-properly-handle-VIRTIO_DECLARE_FEATURES/20250624-221751 >>> base: net-next/main >>> patch link: https://lore.kernel.org/r/23e46bff5333015d92bf0876033750d9fbf555a0.1750753211.git.pabeni%40redhat.com >>> patch subject: [PATCH v6 net-next 4/9] vhost-net: allow configuring extended features >>> config: csky-randconfig-001-20250627 (https://download.01.org/0day-ci/archive/20250627/202506271443.G9cAx8PS-lkp@xxxxxxxxx/config) >>> compiler: csky-linux-gcc (GCC) 15.1.0 >>> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250627/202506271443.G9cAx8PS-lkp@xxxxxxxxx/reproduce) >>> >>> If you fix the issue in a separate patch/commit (i.e. not just a new version of >>> the same patch/commit), kindly add following tags >>> | Reported-by: kernel test robot <lkp@xxxxxxxxx> >>> | Closes: https://lore.kernel.org/oe-kbuild-all/202506271443.G9cAx8PS-lkp@xxxxxxxxx/ >>> >>> All warnings (new ones prefixed by >>): >>> >>> In file included from include/linux/uaccess.h:12, >>> from include/linux/sched/task.h:13, >>> from include/linux/sched/signal.h:9, >>> from include/linux/rcuwait.h:6, >>> from include/linux/percpu-rwsem.h:7, >>> from include/linux/fs.h:34, >>> from include/linux/compat.h:17, >>> from drivers/vhost/net.c:8: >>> arch/csky/include/asm/uaccess.h: In function '__get_user_fn.constprop': >>>>> arch/csky/include/asm/uaccess.h:147:9: warning: 'retval' is used uninitialized [-Wuninitialized] >>> 147 | __asm__ __volatile__( \ >>> | ^~~~~~~ >>> arch/csky/include/asm/uaccess.h:187:17: note: in expansion of macro '__get_user_asm_64' >>> 187 | __get_user_asm_64(x, ptr, retval); >>> | ^~~~~~~~~~~~~~~~~ >>> arch/csky/include/asm/uaccess.h:170:13: note: 'retval' was declared here >>> 170 | int retval; >>> | ^~~~~~ >>> >>> >>> vim +/retval +147 arch/csky/include/asm/uaccess.h >>> >>> da551281947cb2c Guo Ren 2018-09-05 141 >>> e58a41c2226847f Guo Ren 2021-04-21 142 #define __get_user_asm_64(x, ptr, err) \ >>> da551281947cb2c Guo Ren 2018-09-05 143 do { \ >>> da551281947cb2c Guo Ren 2018-09-05 144 int tmp; \ >>> e58a41c2226847f Guo Ren 2021-04-21 145 int errcode; \ >>> e58a41c2226847f Guo Ren 2021-04-21 146 \ >>> e58a41c2226847f Guo Ren 2021-04-21 @147 __asm__ __volatile__( \ >>> e58a41c2226847f Guo Ren 2021-04-21 148 "1: ldw %3, (%2, 0) \n" \ >>> da551281947cb2c Guo Ren 2018-09-05 149 " stw %3, (%1, 0) \n" \ >>> e58a41c2226847f Guo Ren 2021-04-21 150 "2: ldw %3, (%2, 4) \n" \ >>> e58a41c2226847f Guo Ren 2021-04-21 151 " stw %3, (%1, 4) \n" \ >>> e58a41c2226847f Guo Ren 2021-04-21 152 " br 4f \n" \ >>> e58a41c2226847f Guo Ren 2021-04-21 153 "3: mov %0, %4 \n" \ >>> e58a41c2226847f Guo Ren 2021-04-21 154 " br 4f \n" \ >>> da551281947cb2c Guo Ren 2018-09-05 155 ".section __ex_table, \"a\" \n" \ >>> da551281947cb2c Guo Ren 2018-09-05 156 ".align 2 \n" \ >>> e58a41c2226847f Guo Ren 2021-04-21 157 ".long 1b, 3b \n" \ >>> e58a41c2226847f Guo Ren 2021-04-21 158 ".long 2b, 3b \n" \ >>> da551281947cb2c Guo Ren 2018-09-05 159 ".previous \n" \ >>> e58a41c2226847f Guo Ren 2021-04-21 160 "4: \n" \ >>> e58a41c2226847f Guo Ren 2021-04-21 161 : "=r"(err), "=r"(x), "=r"(ptr), \ >>> e58a41c2226847f Guo Ren 2021-04-21 162 "=r"(tmp), "=r"(errcode) \ >>> e58a41c2226847f Guo Ren 2021-04-21 163 : "0"(err), "1"(x), "2"(ptr), "3"(0), \ >>> e58a41c2226847f Guo Ren 2021-04-21 164 "4"(-EFAULT) \ >>> da551281947cb2c Guo Ren 2018-09-05 165 : "memory"); \ >>> da551281947cb2c Guo Ren 2018-09-05 166 } while (0) >>> da551281947cb2c Guo Ren 2018-09-05 167 >> >> AFAICS the issue reported here is in the arch-specific uaccess helpers >> and not related to this series. >> >> /P > > I think it's due to code like this in your patch: > > + if (get_user(features, featurep + 1 + i)) > + return -EFAULT; > > the specific arch might have a bug that this is unconvering, > or a limitation, I can't say. > > Seems worth fixing, though. > > Poke the mainatiners? FTR, I tried the boot reproducer locally, and does not trigger here. The above statement is AFAICS legit, and the issue, if any, is present into such arch. I would not say this patch is 'uncovering' anything, as the relevant pattern is very common. Possibly the test robot added support for csky only recently? I will ping the arch maintainers, but I suggest/argue not blocking this series for this thing. Thanks, Paolo
