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Date:   Mon, 2 Jan 2023 11:27:57 +0100
From:   Marco Elver <elver@google.com>
To:     Vlastimil Babka <vbabka@suse.cz>
Cc:     kernel test robot <lkp@intel.com>, llvm@lists.linux.dev,
        oe-kbuild-all@lists.linux.dev, linux-kernel@vger.kernel.org,
        Christoph Lameter <cl@linux-foundation.org>,
        Alexander Potapenko <glider@google.com>,
        Dmitry Vyukov <dvyukov@google.com>,
        kasan-dev <kasan-dev@googlegroups.com>
Subject: Re: mm/kmsan/instrumentation.c:41:26: warning: no previous prototype
 for function '__msan_metadata_ptr_for_load_n'
Message-ID: <Y7KxrfQ5FQmqVBAn@elver.google.com>
References: <202301020356.dFruA4I5-lkp@intel.com>
 <aa722a69-8493-b449-c80c-a7cc1cf8a1b6@suse.cz>
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On Mon, Jan 02, 2023 at 11:01AM +0100, Vlastimil Babka wrote:
> +CC kmsan folks.
> 
> I think it's another side-effect where CONFIG_SLUB_TINY excludes KASAN which
> in turn allows KMSAN to be enabled and uncover a pre-existing issue.
> 
> On 1/1/23 20:10, kernel test robot wrote:
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > head:   e4cf7c25bae5c3b5089a3c23a897f450149caef2
> > commit: e240e53ae0abb0896e0f399bdfef41c69cec3123 mm, slub: add CONFIG_SLUB_TINY
> > date:   5 weeks ago
> > config: x86_64-randconfig-a013-20230102
> > compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
> > 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://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e240e53ae0abb0896e0f399bdfef41c69cec3123
> >         git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> >         git fetch --no-tags linus master
> >         git checkout e240e53ae0abb0896e0f399bdfef41c69cec3123
> >         # save the config file
> >         mkdir build_dir && cp config build_dir/.config
> >         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 olddefconfig
> >         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash mm/kmsan/
> > 
> > If you fix the issue, kindly add following tag where applicable
> > | Reported-by: kernel test robot <lkp@intel.com>
> > 
> > All warnings (new ones prefixed by >>):
> > 
> >>> mm/kmsan/instrumentation.c:41:26: warning: no previous prototype for function '__msan_metadata_ptr_for_load_n' [-Wmissing-prototypes]
> >    struct shadow_origin_ptr __msan_metadata_ptr_for_load_n(void *addr,

Probably needs a fix similar to:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9dd979bae4cf76558ff816abe83283308fb1ae8c