Re: [PATCH v2 3/3] mm: Add build time sanity chcek for struct page size

[kbuild test robot]

Hi Baoquan,

I love your patch! Yet something to improve:

[auto build test ERROR on tip/auto-latest]
[also build test ERROR on v4.19-rc2 next-20180906]
[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/Baoquan-He/x86-mm-KASLR-Fix-the-wrong-calculation-of-kalsr-region-initial-size/20180910-205421
config: i386-randconfig-x077-201836 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

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

   In file included from include/asm-generic/bug.h:5:0,
                    from arch/x86/include/asm/bug.h:83,
                    from include/linux/bug.h:5,
                    from include/linux/mmdebug.h:5,
                    from include/linux/mm.h:9,
                    from mm/page_alloc.c:18:
   mm/page_alloc.c: In function 'free_area_init_nodes':
   include/linux/kernel.h:845:29: warning: comparison of distinct pointer types lacks a cast
      (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
                                ^
   include/linux/compiler.h:335:18: note: in definition of macro '__compiletime_assert'
      int __cond = !(condition);    \
                     ^~~~~~~~~
   include/linux/compiler.h:358:2: note: in expansion of macro '_compiletime_assert'
     _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
     ^~~~~~~~~~~~~~~~~~~
   include/linux/build_bug.h:45:37: note: in expansion of macro 'compiletime_assert'
    #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
                                        ^~~~~~~~~~~~~~~~~~
   include/linux/build_bug.h:69:2: note: in expansion of macro 'BUILD_BUG_ON_MSG'
     BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
     ^~~~~~~~~~~~~~~~
>> mm/page_alloc.c:6852:2: note: in expansion of macro 'BUILD_BUG_ON'
     BUILD_BUG_ON(sizeof(struct page) < min(SZ_1K, PAGE_SIZE/4));
     ^~~~~~~~~~~~
   include/linux/kernel.h:859:4: note: in expansion of macro '__typecheck'
      (__typecheck(x, y) && __no_side_effects(x, y))
       ^~~~~~~~~~~
   include/linux/kernel.h:869:24: note: in expansion of macro '__safe_cmp'
     __builtin_choose_expr(__safe_cmp(x, y), \
                           ^~~~~~~~~~
   include/linux/kernel.h:878:19: note: in expansion of macro '__careful_cmp'
    #define min(x, y) __careful_cmp(x, y, <)
                      ^~~~~~~~~~~~~
>> mm/page_alloc.c:6852:37: note: in expansion of macro 'min'
     BUILD_BUG_ON(sizeof(struct page) < min(SZ_1K, PAGE_SIZE/4));
                                        ^~~
>> include/linux/compiler.h:358:38: error: call to '__compiletime_assert_6852' declared with attribute error: BUILD_BUG_ON failed: sizeof(struct page) < min(SZ_1K, PAGE_SIZE/4)
     _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
                                         ^
   include/linux/compiler.h:338:4: note: in definition of macro '__compiletime_assert'
       prefix ## suffix();    \
       ^~~~~~
   include/linux/compiler.h:358:2: note: in expansion of macro '_compiletime_assert'
     _compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
     ^~~~~~~~~~~~~~~~~~~
   include/linux/build_bug.h:45:37: note: in expansion of macro 'compiletime_assert'
    #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg)
                                        ^~~~~~~~~~~~~~~~~~
   include/linux/build_bug.h:69:2: note: in expansion of macro 'BUILD_BUG_ON_MSG'
     BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition)
     ^~~~~~~~~~~~~~~~
>> mm/page_alloc.c:6852:2: note: in expansion of macro 'BUILD_BUG_ON'
     BUILD_BUG_ON(sizeof(struct page) < min(SZ_1K, PAGE_SIZE/4));
     ^~~~~~~~~~~~

vim +/__compiletime_assert_6852 +358 include/linux/compiler.h

9a8ab1c3 Daniel Santos 2013-02-21  344  
9a8ab1c3 Daniel Santos 2013-02-21  345  #define _compiletime_assert(condition, msg, prefix, suffix) \
9a8ab1c3 Daniel Santos 2013-02-21  346  	__compiletime_assert(condition, msg, prefix, suffix)
9a8ab1c3 Daniel Santos 2013-02-21  347  
9a8ab1c3 Daniel Santos 2013-02-21  348  /**
9a8ab1c3 Daniel Santos 2013-02-21  349   * compiletime_assert - break build and emit msg if condition is false
9a8ab1c3 Daniel Santos 2013-02-21  350   * @condition: a compile-time constant condition to check
9a8ab1c3 Daniel Santos 2013-02-21  351   * @msg:       a message to emit if condition is false
9a8ab1c3 Daniel Santos 2013-02-21  352   *
9a8ab1c3 Daniel Santos 2013-02-21  353   * In tradition of POSIX assert, this macro will break the build if the
9a8ab1c3 Daniel Santos 2013-02-21  354   * supplied condition is *false*, emitting the supplied error message if the
9a8ab1c3 Daniel Santos 2013-02-21  355   * compiler has support to do so.
9a8ab1c3 Daniel Santos 2013-02-21  356   */
9a8ab1c3 Daniel Santos 2013-02-21  357  #define compiletime_assert(condition, msg) \
9a8ab1c3 Daniel Santos 2013-02-21 @358  	_compiletime_assert(condition, msg, __compiletime_assert_, __LINE__)
9a8ab1c3 Daniel Santos 2013-02-21  359  

:::::: The code at line 358 was first introduced by commit
:::::: 9a8ab1c39970a4938a72d94e6fd13be88a797590 bug.h, compiler.h: introduce compiletime_assert & BUILD_BUG_ON_MSG

:::::: TO: Daniel Santos <daniel.santos@xxxxxxxxx>
:::::: CC: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>

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

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