Hi Dan,

I love your patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v4.18-rc3]
[cannot apply to next-20180704]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Dan-Williams/device-dax-Convert-to-vmf_insert_mixed-and-vm_fault_t/20180705-075150
config: openrisc-or1ksim_defconfig (attached as .config)
compiler: or1k-linux-gcc (GCC) 6.0.0 20160327 (experimental)
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=openrisc 

All error/warnings (new ones prefixed by >>):

   In file included from include/linux/mempolicy.h:11:0,
                    from init/main.c:56:
   include/linux/dax.h: In function 'dax_lock_mapping_entry':
   include/linux/dax.h:128:15: error: 'page' redeclared as different kind of symbol
     struct page *page = pfn_to_page(pfn);
                  ^~~~
   include/linux/dax.h:126:56: note: previous definition of 'page' was here
    static inline bool dax_lock_mapping_entry(struct page *page)
                                                           ^~~~
   In file included from arch/openrisc/include/asm/page.h:98:0,
                    from arch/openrisc/include/asm/processor.h:23,
                    from arch/openrisc/include/asm/thread_info.h:26,
                    from include/linux/thread_info.h:38,
                    from include/asm-generic/preempt.h:5,
                    from ./arch/openrisc/include/generated/asm/preempt.h:1,
                    from include/linux/preempt.h:81,
                    from include/linux/spinlock.h:51,
                    from include/linux/seqlock.h:36,
                    from include/linux/time.h:6,
                    from include/linux/stat.h:19,
                    from include/linux/module.h:10,
                    from init/main.c:16:
>> include/linux/dax.h:128:34: error: 'pfn' undeclared (first use in this function)
     struct page *page = pfn_to_page(pfn);
                                     ^
   include/asm-generic/memory_model.h:33:41: note: in definition of macro '__pfn_to_page'
    #define __pfn_to_page(pfn) (mem_map + ((pfn) - ARCH_PFN_OFFSET))
                                            ^~~
>> include/linux/dax.h:128:22: note: in expansion of macro 'pfn_to_page'
     struct page *page = pfn_to_page(pfn);
                         ^~~~~~~~~~~
   include/linux/dax.h:128:34: note: each undeclared identifier is reported only once for each function it appears in
     struct page *page = pfn_to_page(pfn);
                                     ^
   include/asm-generic/memory_model.h:33:41: note: in definition of macro '__pfn_to_page'
    #define __pfn_to_page(pfn) (mem_map + ((pfn) - ARCH_PFN_OFFSET))
                                            ^~~
>> include/linux/dax.h:128:22: note: in expansion of macro 'pfn_to_page'
     struct page *page = pfn_to_page(pfn);
                         ^~~~~~~~~~~
   In file included from include/linux/mempolicy.h:11:0,
                    from init/main.c:56:
   include/linux/dax.h: In function 'dax_lock_page':
   include/linux/dax.h:141:1: warning: no return statement in function returning non-void [-Wreturn-type]
    }
    ^

vim +/pfn +128 include/linux/dax.h

   124	
   125	
   126	static inline bool dax_lock_mapping_entry(struct page *page)
   127	{
 > 128		struct page *page = pfn_to_page(pfn);
   129	
   130		if (IS_DAX(page->mapping->host))
   131			return true;
   132		return false;
   133	}
   134	

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