Re: mm/khugepaged.c:2046:56: warning: 'struct khugepaged_mm_slot' declared inside parameter list will not be visible outside of this definition or declaration

[Qi Zheng]

On 2022/9/2 22:23, kernel test robot wrote:
> tree:   https://github.com/intel-lab-lkp/linux/commits/UPDATE-20220901-154717/Qi-Zheng/add-common-struct-mm_slot-and-use-it-in-THP-and-KSM/20220831-112149
> head:   32b787e37af17f7fe75f9b9c9bb22bf044722229
> commit: 7ad02cf1645071c2bf1ed6ae0e48907aa0a3119e mm: thp: fix build error with CONFIG_SHMEM disabled
> date:   30 hours ago
> config: sparc-randconfig-r023-20220901 (https://download.01.org/0day-ci/archive/20220902/202209022248.TEjW4Cld-lkp@xxxxxxxxx/config)
> compiler: sparc64-linux-gcc (GCC) 12.1.0
> 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/intel-lab-lkp/linux/commit/7ad02cf1645071c2bf1ed6ae0e48907aa0a3119e
>          git remote add linux-review https://github.com/intel-lab-lkp/linux
>          git fetch --no-tags linux-review UPDATE-20220901-154717/Qi-Zheng/add-common-struct-mm_slot-and-use-it-in-THP-and-KSM/20220831-112149
>          git checkout 7ad02cf1645071c2bf1ed6ae0e48907aa0a3119e
>          # save the config file
>          mkdir build_dir && cp config build_dir/.config
>          COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=sparc SHELL=/bin/bash
>
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
>
> All warnings (new ones prefixed by >>):
>
> > > mm/khugepaged.c:2046:56: warning: 'struct khugepaged_mm_slot' declared inside parameter list will not be visible outside of this definition or declaration
>      2046 | static void khugepaged_collapse_pte_mapped_thps(struct khugepaged_mm_slot *mm_slot)
>           |                                                        ^~~~~~~~~~~~~~~~~~
>     mm/khugepaged.c: In function 'khugepaged_scan_mm_slot':
>     mm/khugepaged.c:2076:45: error: passing argument 1 of 'khugepaged_collapse_pte_mapped_thps' from incompatible pointer type [-Werror=incompatible-pointer-types]
>      2076 |         khugepaged_collapse_pte_mapped_thps(mm_slot);
>           |                                             ^~~~~~~
>           |                                             |
>           |                                             struct mm_slot *

It looks like the robot tested "mm: thp: fix build error with
CONFIG_SHMEM disabled" alone without "[PATCH v2 2/7] mm: thp: convert to
use common struct mm_slot". So this is a false positive.

>     mm/khugepaged.c:2046:76: note: expected 'struct khugepaged_mm_slot *' but argument is of type 'struct mm_slot *'
>      2046 | static void khugepaged_collapse_pte_mapped_thps(struct khugepaged_mm_slot *mm_slot)
>           |                                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~
>     cc1: some warnings being treated as errors
>
>
> vim +2046 mm/khugepaged.c
>
>    2045	
> > 2046	static void khugepaged_collapse_pte_mapped_thps(struct khugepaged_mm_slot *mm_slot)
>    2047	{
>    2048	}
>    2049	#endif
>    2050	

--
Thanks,
Qi