Hi Pavel,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on mmotm/master]
[also build test WARNING on v4.15 next-20180201]
[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/Pavel-Tatashin/mm-uninitialized-struct-page-poisoning-sanity-checking/20180202-105827
base:   git://git.cmpxchg.org/linux-mmotm.git master
config: x86_64-randconfig-x013-201804 (attached as .config)
compiler: gcc-7 (Debian 7.2.0-12) 7.2.1 20171025
reproduce:
        # save the attached .config to linux build tree
        make ARCH=x86_64 

All warnings (new ones prefixed by >>):

   In file included from include/linux/page_ref.h:7:0,
                    from include/linux/mm.h:26,
                    from include/linux/memblock.h:18,
                    from mm/memblock.c:21:
   mm/memblock.c: In function 'memblock_virt_alloc_try_nid_raw':

quoted

include/linux/page-flags.h:159:29: warning: overflow in implicit constant conversion [-Woverflow]

    #define PAGE_POISON_PATTERN ~0ul
                                ^

quoted

mm/memblock.c:1376:15: note: in expansion of macro 'PAGE_POISON_PATTERN'

      memset(ptr, PAGE_POISON_PATTERN, size);
                  ^~~~~~~~~~~~~~~~~~~

vim +159 include/linux/page-flags.h

   158	
 > 159	#define	PAGE_POISON_PATTERN	~0ul
   160	static inline int PagePoisoned(const struct page *page)
   161	{
   162		return page->flags == PAGE_POISON_PATTERN;
   163	}
   164	

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