Hi "Matthew,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on next-20201215]
[cannot apply to kdave/for-next ceph-client/for-linus linus/master hnaz-linux-mm/master v5.10 v5.10-rc7 v5.10-rc6 v5.10]
[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]

url:    https://github.com/0day-ci/linux/commits/Matthew-Wilcox-Oracle/Page-folios/20201217-023021
base:    9317f948b0b188b8d2fded75957e6d42c460df1b
config: powerpc64-randconfig-p002-20201216 (attached as .config)
compiler: powerpc64-linux-gcc (GCC) 9.3.0
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/0day-ci/linux/commit/7611dc869e8fa7240e3c841bffe6a88e46a802c6
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Matthew-Wilcox-Oracle/Page-folios/20201217-023021
        git checkout 7611dc869e8fa7240e3c841bffe6a88e46a802c6
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=powerpc64 

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

All errors (new ones prefixed by >>):

   In file included from arch/powerpc/include/asm/cacheflush.h:111,
                    from include/linux/highmem.h:12,
                    from include/linux/pagemap.h:11,
                    from include/linux/blkdev.h:14,
                    from include/linux/blk-cgroup.h:23,
                    from include/linux/writeback.h:14,
                    from include/linux/memcontrol.h:22,
                    from include/linux/swap.h:9,
                    from include/linux/suspend.h:5,
                    from arch/powerpc/kernel/asm-offsets.c:23:
   include/asm-generic/cacheflush.h: In function 'flush_dcache_folio':
>> include/asm-generic/cacheflush.h:64:33: error: subscripted value is neither array nor pointer nor vector
      64 |   flush_dcache_page(&folio->page[--n]);
         |                                 ^
--
   In file included from arch/powerpc/include/asm/cacheflush.h:111,
                    from include/linux/highmem.h:12,
                    from include/linux/pagemap.h:11,
                    from include/linux/blkdev.h:14,
                    from include/linux/blk-cgroup.h:23,
                    from include/linux/writeback.h:14,
                    from include/linux/memcontrol.h:22,
                    from include/linux/swap.h:9,
                    from include/linux/suspend.h:5,
                    from arch/powerpc/kernel/asm-offsets.c:23:
   include/asm-generic/cacheflush.h: In function 'flush_dcache_folio':
>> include/asm-generic/cacheflush.h:64:33: error: subscripted value is neither array nor pointer nor vector
      64 |   flush_dcache_page(&folio->page[--n]);
         |                                 ^
   make[2]: *** [scripts/Makefile.build:117: arch/powerpc/kernel/asm-offsets.s] Error 1
   make[2]: Target '__build' not remade because of errors.
   make[1]: *** [Makefile:1206: prepare0] Error 2
   make[1]: Target 'modules_prepare' not remade because of errors.
   make: *** [Makefile:185: __sub-make] Error 2
   make: Target 'modules_prepare' not remade because of errors.
--
   In file included from arch/powerpc/include/asm/cacheflush.h:111,
                    from include/linux/highmem.h:12,
                    from include/linux/pagemap.h:11,
                    from include/linux/blkdev.h:14,
                    from include/linux/blk-cgroup.h:23,
                    from include/linux/writeback.h:14,
                    from include/linux/memcontrol.h:22,
                    from include/linux/swap.h:9,
                    from include/linux/suspend.h:5,
                    from arch/powerpc/kernel/asm-offsets.c:23:
   include/asm-generic/cacheflush.h: In function 'flush_dcache_folio':
>> include/asm-generic/cacheflush.h:64:33: error: subscripted value is neither array nor pointer nor vector
      64 |   flush_dcache_page(&folio->page[--n]);
         |                                 ^
   make[2]: *** [scripts/Makefile.build:117: arch/powerpc/kernel/asm-offsets.s] Error 1
   make[2]: Target '__build' not remade because of errors.
   make[1]: *** [Makefile:1206: prepare0] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [Makefile:185: __sub-make] Error 2
   make: Target 'prepare' not remade because of errors.


vim +64 include/asm-generic/cacheflush.h

    57	
    58	#ifndef ARCH_IMPLEMENTS_FLUSH_DCACHE_FOLIO
    59	static inline void flush_dcache_folio(struct folio *folio)
    60	{
    61		unsigned int n = folio_nr_pages(folio);
    62	
    63		do {
  > 64			flush_dcache_page(&folio->page[--n]);
    65		} while (n);
    66	}
    67	#endif
    68	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org