On Mon, Jan 31, 2022 at 02:07:02PM +0100, Greg Kroah-Hartman wrote: > On Mon, Jan 31, 2022 at 07:16:01PM +0800, kernel test robot wrote: > > Hi Nguyen, > > > > Thank you for the patch! Perhaps something to improve: > > > > [auto build test WARNING on staging/staging-testing] > > > > url: https://github.com/0day-ci/linux/commits/Nguyen-Dinh-Phi/staging-vc04_services-make-a-couple-of-functions-static/20220131-151209 > > base: https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git 64b2d6ffff862c0e7278198b4229e42e1abb3bb1 > > config: arm-randconfig-r002-20220130 (https://download.01.org/0day-ci/archive/20220131/202201311901.HT4PtVja-lkp@xxxxxxxxx/config) > > compiler: arm-linux-gnueabi-gcc (GCC) 11.2.0 > > reproduce (this is a W=1 build): > > wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross > > chmod +x ~/bin/make.cross > > # https://github.com/0day-ci/linux/commit/1b64825a2b5b3312ae309c1714239df049b018ac > > git remote add linux-review https://github.com/0day-ci/linux > > git fetch --no-tags linux-review Nguyen-Dinh-Phi/staging-vc04_services-make-a-couple-of-functions-static/20220131-151209 > > git checkout 1b64825a2b5b3312ae309c1714239df049b018ac > > # save the config file to linux build tree > > mkdir build_dir > > COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross O=build_dir ARCH=arm SHELL=/bin/bash drivers/staging/vc04_services/ > > > > If you fix the issue, kindly add following tag as appropriate > > Reported-by: kernel test robot <lkp@xxxxxxxxx> > > > > All warnings (new ones prefixed by >>): > > > > drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c: In function 'free_pagelist': > > >> drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c:434:25: warning: argument 2 null where non-null expected [-Wnonnull] > > 434 | memcpy((char *)kmap(pages[0]) + > > | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > > 435 | pagelist->offset, > > | ~~~~~~~~~~~~~~~~~ > > 436 | fragments, > > | ~~~~~~~~~~ > > 437 | head_bytes); > > | ~~~~~~~~~~~ > > In file included from include/linux/string.h:20, > > from include/linux/bitmap.h:11, > > from include/linux/cpumask.h:12, > > from include/linux/mm_types_task.h:14, > > from include/linux/mm_types.h:5, > > from include/linux/buildid.h:5, > > from include/linux/module.h:14, > > from drivers/staging/vc04_services/interface/vchiq_arm/vchiq_arm.c:8: > > arch/arm/include/asm/string.h:20:15: note: in a call to function 'memcpy' declared 'nonnull' > > 20 | extern void * memcpy(void *, const void *, __kernel_size_t); > > | ^~~~~~ > > > > Oddly, your patch caused these build errors to happen, which implies > that you did not test-build your patch? > > I remember seeing this before and being confused as to why this type of > change would cause this error, but it must be for some reason, which > means we can't take this patch. > > Always test-build your changes before sending them out. > This is an annoying thing. Unless I'm mistaken, it's a totally nonsense GCC false positive. In Smatch, I have a similar NULL dereference check, but I have never felt confident enough to harrass people with false positives even though mine are fewer. (Smatch has *way* better flow analysis than GCC but the tradeoff is that Smatch is slower.) I can't understand why this warning triggers on this particular patch. It has to do with the .config. A make allmodconfig will not trigger it, but the kbuild .config does. Possibly to do with chance and inlining. regards, dan carpenter
