Re: [PATCH 2/2] Add /proc/PID/{smaps, numa_maps} support for DAX

[kbuild test robot <lkp@xxxxxxxxx>]

Hi Fan,

Thank you for the patch! Yet we hit a small issue.
[auto build test WARNING on linus/master]
[also build test WARNING on v4.14-rc6 next-20171018]
[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/Fan-Du/proc-mm-export-PTE-sizes-directly-in-smaps/20171027-233355
config: i386-randconfig-b0-10280854 (attached as .config)
compiler: gcc-5 (Debian 5.4.1-2) 5.4.1 20160904
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

Note: it may well be a FALSE warning. FWIW you are at least aware of it now.
http://gcc.gnu.org/wiki/Better_Uninitialized_Warnings

All warnings (new ones prefixed by >>):

   In file included from arch/x86/include/asm/processor.h:31:0,
                    from arch/x86/include/asm/cpufeature.h:4,
                    from arch/x86/include/asm/thread_info.h:52,
                    from include/linux/thread_info.h:37,
                    from arch/x86/include/asm/preempt.h:6,
                    from include/linux/preempt.h:80,
                    from include/linux/spinlock.h:50,
                    from include/linux/mmzone.h:7,
                    from include/linux/gfp.h:5,
                    from include/linux/mm.h:9,
                    from fs/proc/task_mmu.c:1:
   fs/proc/task_mmu.c: In function 'smaps_pte_range':
>> include/linux/err.h:40:24: warning: 'page' may be used uninitialized in this function [-Wmaybe-uninitialized]
     return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr);
                           ^
   fs/proc/task_mmu.c:586:15: note: 'page' was declared here
     struct page *page;
                  ^
--
   In file included from arch/x86/include/asm/processor.h:31:0,
                    from arch/x86/include/asm/cpufeature.h:4,
                    from arch/x86/include/asm/thread_info.h:52,
                    from include/linux/thread_info.h:37,
                    from arch/x86/include/asm/preempt.h:6,
                    from include/linux/preempt.h:80,
                    from include/linux/spinlock.h:50,
                    from include/linux/mmzone.h:7,
                    from include/linux/gfp.h:5,
                    from include/linux/mm.h:9,
                    from fs//proc/task_mmu.c:1:
   fs//proc/task_mmu.c: In function 'smaps_pte_range':
>> include/linux/err.h:40:24: warning: 'page' may be used uninitialized in this function [-Wmaybe-uninitialized]
     return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr);
                           ^
   fs//proc/task_mmu.c:586:15: note: 'page' was declared here
     struct page *page;
                  ^

vim +/page +40 include/linux/err.h

^1da177e Linus Torvalds 2005-04-16  37  
a5ed3cee Joe Perches    2014-04-03  38  static inline bool __must_check IS_ERR_OR_NULL(__force const void *ptr)
603c4ba9 Phil Carmody   2009-12-14  39  {
dfffa587 Viresh Kumar   2016-01-15 @40  	return unlikely(!ptr) || IS_ERR_VALUE((unsigned long)ptr);
603c4ba9 Phil Carmody   2009-12-14  41  }
603c4ba9 Phil Carmody   2009-12-14  42  

:::::: The code at line 40 was first introduced by commit
:::::: dfffa587a6bcd84f2087f88e11600b0e8b0aa1ee err.h: add (missing) unlikely() to IS_ERR_OR_NULL()

:::::: TO: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
:::::: CC: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>

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0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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