tree:   git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
head:   7732a9817fb01002bde7615066e86c156fb5a31b
commit: 0491d0d6aac97c5b8df17851db525f3758de26e6 [7235/7555] s390/mm: make hugepages_supported a boot time decision
config: s390-defconfig (attached as .config)
reproduce:
  wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
  chmod +x ~/bin/make.cross
  git checkout 0491d0d6aac97c5b8df17851db525f3758de26e6
  # save the attached .config to linux build tree
  make.cross ARCH=s390 

All warnings:

   mm/page_alloc.c: In function '__free_one_page':
>> mm/page_alloc.c:654:121: warning: comparison of distinct pointer types lacks a cast
      max_order = min(MAX_ORDER, pageblock_order + 1);
                                                                                                                            ^
--
   mm/cma.c: In function 'cma_init_reserved_mem':
>> mm/cma.c:186:137: warning: comparison of distinct pointer types lacks a cast
     alignment = PAGE_SIZE << max(MAX_ORDER - 1, pageblock_order);
                                                                                                                                            ^
   mm/cma.c: In function 'cma_declare_contiguous':
>> mm/cma.c:269:199: warning: comparison of distinct pointer types lacks a cast
     alignment = max(alignment,
                                                                                                                                                                                                          ^
>> mm/cma.c:269:391: warning: comparison of distinct pointer types lacks a cast
     alignment = max(alignment,
                                                                                                                                                                                                                                                                                                                                                                                                          ^

vim +654 mm/page_alloc.c

6dda9d55bf Corrado Zoccolo    2010-05-24  638  	unsigned long combined_idx;
43506fad21 KyongHo Cho        2011-01-13  639  	unsigned long uninitialized_var(buddy_idx);
6dda9d55bf Corrado Zoccolo    2010-05-24  640  	struct page *buddy;
3c605096d3 Joonsoo Kim        2014-11-13  641  	int max_order = MAX_ORDER;
^1da177e4c Linus Torvalds     2005-04-16  642  
d29bb9782d Cody P Schafer     2013-02-22  643  	VM_BUG_ON(!zone_is_initialized(zone));
6e9f0d582d Kirill A. Shutemov 2015-02-11  644  	VM_BUG_ON_PAGE(page->flags & PAGE_FLAGS_CHECK_AT_PREP, page);
^1da177e4c Linus Torvalds     2005-04-16  645  
ed0ae21dc5 Mel Gorman         2009-06-16  646  	VM_BUG_ON(migratetype == -1);
3c605096d3 Joonsoo Kim        2014-11-13  647  	if (is_migrate_isolate(migratetype)) {
3c605096d3 Joonsoo Kim        2014-11-13  648  		/*
3c605096d3 Joonsoo Kim        2014-11-13  649  		 * We restrict max order of merging to prevent merge
3c605096d3 Joonsoo Kim        2014-11-13  650  		 * between freepages on isolate pageblock and normal
3c605096d3 Joonsoo Kim        2014-11-13  651  		 * pageblock. Without this, pageblock isolation
3c605096d3 Joonsoo Kim        2014-11-13  652  		 * could cause incorrect freepage accounting.
3c605096d3 Joonsoo Kim        2014-11-13  653  		 */
3c605096d3 Joonsoo Kim        2014-11-13 @654  		max_order = min(MAX_ORDER, pageblock_order + 1);
3c605096d3 Joonsoo Kim        2014-11-13  655  	} else {
8f82b55dd5 Joonsoo Kim        2014-11-13  656  		__mod_zone_freepage_state(zone, 1 << order, migratetype);
3c605096d3 Joonsoo Kim        2014-11-13  657  	}
ed0ae21dc5 Mel Gorman         2009-06-16  658  
3c605096d3 Joonsoo Kim        2014-11-13  659  	page_idx = pfn & ((1 << max_order) - 1);
^1da177e4c Linus Torvalds     2005-04-16  660  
309381feae Sasha Levin        2014-01-23  661  	VM_BUG_ON_PAGE(page_idx & ((1 << order) - 1), page);
309381feae Sasha Levin        2014-01-23  662  	VM_BUG_ON_PAGE(bad_range(zone, page), page);

:::::: The code at line 654 was first introduced by commit
:::::: 3c605096d3158216ba9326a16266f6ba128c2c8d mm/page_alloc: restrict max order of merging on isolated pageblock

:::::: TO: Joonsoo Kim <iamjoonsoo.kim@lge.com>
:::::: CC: Linus Torvalds <torvalds@linux-foundation.org>

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