Re: [PATCH v2] net: skbuff: add usercopy region to skbuff_fclone_cache

[kernel test robot <lkp@intel.com>]

Hi Weiming,

kernel test robot noticed the following build warnings:

[auto build test WARNING on net-next/main]
[also build test WARNING on net/main linus/master v6.19-rc1 next-20251219]
[cannot apply to horms-ipvs/master]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Weiming-Shi/net-skbuff-add-usercopy-region-to-skbuff_fclone_cache/20251216-021811
base:   net-next/main
patch link:    https://lore.kernel.org/r/20251215180903.954968-2-bestswngs%40gmail.com
patch subject: [PATCH v2] net: skbuff: add usercopy region to skbuff_fclone_cache
config: arm-randconfig-r073-20251216 (https://download.01.org/0day-ci/archive/20251220/202512202310.PGCBLw9b-lkp@intel.com/config)
compiler: arm-linux-gnueabi-gcc (GCC) 10.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251220/202512202310.PGCBLw9b-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/202512202310.PGCBLw9b-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from include/uapi/linux/posix_types.h:5,
                    from include/uapi/linux/types.h:14,
                    from include/linux/types.h:6,
                    from include/linux/kasan-checks.h:5,
                    from include/asm-generic/rwonce.h:26,
                    from ./arch/arm/include/generated/asm/rwonce.h:1,
                    from include/linux/compiler.h:386,
                    from include/linux/build_bug.h:5,
                    from include/linux/container_of.h:5,
                    from include/linux/list.h:5,
                    from include/linux/module.h:12,
                    from net/core/skbuff.c:37:
   net/core/skbuff.c: In function 'skb_init':
>> include/linux/stddef.h:8:14: warning: passing argument 5 of 'kmem_cache_create_usercopy' makes integer from pointer without a cast [-Wint-conversion]
       8 | #define NULL ((void *)0)
         |              ^~~~~~~~~~~
         |              |
         |              void *
   net/core/skbuff.c:5164:7: note: in expansion of macro 'NULL'
    5164 |       NULL);
         |       ^~~~
   In file included from arch/arm/include/asm/pgtable-nommu.h:13,
                    from arch/arm/include/asm/pgtable.h:25,
                    from include/linux/pgtable.h:6,
                    from include/linux/mm.h:31,
                    from net/core/skbuff.c:40:
   include/linux/slab.h:408:20: note: expected 'unsigned int' but argument is of type 'void *'
     408 |       unsigned int useroffset, unsigned int usersize,
         |       ~~~~~~~~~~~~~^~~~~~~~~~
   net/core/skbuff.c:5160:36: error: too few arguments to function 'kmem_cache_create_usercopy'
    5160 |  net_hotdata.skbuff_fclone_cache = kmem_cache_create_usercopy("skbuff_fclone_cache",
         |                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~
   In file included from arch/arm/include/asm/pgtable-nommu.h:13,
                    from arch/arm/include/asm/pgtable.h:25,
                    from include/linux/pgtable.h:6,
                    from include/linux/mm.h:31,
                    from net/core/skbuff.c:40:
   include/linux/slab.h:406:1: note: declared here
     406 | kmem_cache_create_usercopy(const char *name, unsigned int size,
         | ^~~~~~~~~~~~~~~~~~~~~~~~~~

Kconfig warnings: (for reference only)
   WARNING: unmet direct dependencies detected for CAN_DEV
   Depends on [n]: NETDEVICES [=n] && CAN [=y]
   Selected by [y]:
   - CAN [=y] && NET [=y]


vim +/kmem_cache_create_usercopy +8 include/linux/stddef.h

^1da177e4c3f41 Linus Torvalds   2005-04-16  6  
^1da177e4c3f41 Linus Torvalds   2005-04-16  7  #undef NULL
^1da177e4c3f41 Linus Torvalds   2005-04-16 @8  #define NULL ((void *)0)
6e218287432472 Richard Knutsson 2006-09-30  9  

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki