Re: [linux-next:master 2203/5042] WARNING: modpost: vmlinux: section mismatch in reference: bitmap_read+0x128 (section: .text.unlikely) -> __setup_str_initcall_blacklist (section: .init.rodata)

["Liu, Yujie" <yujie.liu@intel.com>]

Hi Andy,

On Wed, 2024-04-10 at 18:27 +0300, Andy Shevchenko wrote:
> On Wed, Apr 10, 2024 at 11:22:16PM +0800, kernel test robot wrote:
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
> > head:   6ebf211bb11dfc004a2ff73a9de5386fa309c430
> > commit: 991e5583647d33ee3a9c89248974ef98b9f539a8 [2203/5042] lib/test_bitmap: add tests for bitmap_{read,write}()
> > config: xtensa-randconfig-r012-20230725 (https://download.01.org/0day-ci/archive/20240410/202404102353.Cv1gUjk3-lkp@intel.com/config)
> > compiler: xtensa-linux-gcc (GCC) 13.2.0
> > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240410/202404102353.Cv1gUjk3-lkp@intel.com/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@intel.com>
> > > Closes: https://lore.kernel.org/oe-kbuild-all/202404102353.Cv1gUjk3-lkp@intel.com/
> > 
> > All warnings (new ones prefixed by >>, old ones prefixed by <<):
> > 
> > WARNING: modpost: missing MODULE_DESCRIPTION() in vmlinux.o
> > > > WARNING: modpost: vmlinux: section mismatch in reference: bitmap_read+0x128 (section: .text.unlikely) -> __setup_str_initcall_blacklist (section: .init.rodata)
> > WARNING: modpost: vmlinux: section mismatch in reference: bitmap_allocate_region+0xb4 (section: .text.unlikely) -> __setup_str_initcall_blacklist (section: .init.rodata)
> 
> As pointed out earlier, this is unconfirmed bug in GCC (GCC developers
> point a finger at kernel code and vice versa). Can you reproduce this
> with clang?

Thanks for the reminder of the previous comment in [1].

[1] https://lore.kernel.org/all/202403121032.WDY8ftKq-lkp@intel.com/

This warning was captured in a randconfig cross compilation for xtensa
architecture. Seems clang doesn't support xtensa backend yet. We tried
some randconfig build for x86_64 with clang, but cannot reproduce
this. 

We only observed this warning on xtensa, but not on other
architectures, so we don't have other configs at hand that can be used
to reproduce with clang. Sorry for this.

--
Best Regards,
Yujie