Hi Pasha,

I love your patch! Yet something to improve:

[auto build test ERROR on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/Pasha-Tatashin/mm-page_ext-Do-not-allocate-space-for-page_ext-flags-if-not-needed/20230112-055942
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20230111215906.2645056-1-pasha.tatashin%40soleen.com
patch subject: [PATCH] mm/page_ext: Do not allocate space for page_ext->flags if not needed
config: hexagon-randconfig-r012-20230110
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 8d9828ef5aa9688500657d36cd2aefbe12bbd162)
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/f195fe7b408dd821eef3d052e8ebd50cccb3df51
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Pasha-Tatashin/mm-page_ext-Do-not-allocate-space-for-page_ext-flags-if-not-needed/20230112-055942
        git checkout f195fe7b408dd821eef3d052e8ebd50cccb3df51
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   In file included from mm/page_owner.c:6:
   In file included from include/linux/memblock.h:13:
   In file included from arch/hexagon/include/asm/dma.h:9:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:547:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __raw_readb(PCI_IOBASE + addr);
                             ~~~~~~~~~~ ^
   include/asm-generic/io.h:560:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
                                                           ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:37:51: note: expanded from macro '__le16_to_cpu'
   #define __le16_to_cpu(x) ((__force __u16)(__le16)(x))
                                                     ^
   In file included from mm/page_owner.c:6:
   In file included from include/linux/memblock.h:13:
   In file included from arch/hexagon/include/asm/dma.h:9:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:573:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
                                                           ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:35:51: note: expanded from macro '__le32_to_cpu'
   #define __le32_to_cpu(x) ((__force __u32)(__le32)(x))
                                                     ^
   In file included from mm/page_owner.c:6:
   In file included from include/linux/memblock.h:13:
   In file included from arch/hexagon/include/asm/dma.h:9:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:584:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writeb(value, PCI_IOBASE + addr);
                               ~~~~~~~~~~ ^
   include/asm-generic/io.h:594:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
                                                         ~~~~~~~~~~ ^
   include/asm-generic/io.h:604:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
                                                         ~~~~~~~~~~ ^
>> mm/page_owner.c:102:3: error: field designator 'using_shared_flags' does not refer to any field in type 'struct page_ext_operations'; did you mean 'using_shared_ext_flags'?
           .using_shared_flags = true,
            ^~~~~~~~~~~~~~~~~~
            using_shared_ext_flags
   include/linux/page_ext.h:15:7: note: 'using_shared_ext_flags' declared here
           bool using_shared_ext_flags;
                ^
   6 warnings and 1 error generated.


vim +102 mm/page_owner.c

    97	
    98	struct page_ext_operations page_owner_ops = {
    99		.size = sizeof(struct page_owner),
   100		.need = need_page_owner,
   101		.init = init_page_owner,
 > 102		.using_shared_flags = true,
   103	};
   104	

-- 
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https://github.com/intel/lkp-tests