[harry:kmalloc-no-objext-rfc-v1r2 3/3] mm/internal.h:838:26: warning: implicit conversion from 'unsigned long long' to 'u32' (aka 'unsigned int') changes value from 17179869184 to 0

[harry:kmalloc-no-objext-rfc-v1r2 3/3] mm/internal.h:838:26: warning: implicit conversion from 'unsigned long long' to 'u32' (aka 'unsigned int') changes value from 17179869184 to 0

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/harry/linux.git kmalloc-no-objext-rfc-v1r2
head:   a734609d2f387a9e682d352e9f28599744cc300b
commit: a734609d2f387a9e682d352e9f28599744cc300b [3/3] mm/slab: prevent unbounded recursion in free path with new kmalloc type
config: x86_64-randconfig-016-20260702 (https://download.01.org/0day-ci/archive/20260702/202607021730.dIjpsiXL-lkp@intel.com/config)
compiler: clang version 22.1.3 (https://github.com/llvm/llvm-project e9846648fd6183ee6d8cbdb4502213fcf902a211)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260702/202607021730.dIjpsiXL-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202607021730.dIjpsiXL-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from mm/slub.c:23:
   mm/slab.h:397:10: error: use of undeclared identifier 'KMALLOC_NO_OBJ_EXT'
     397 |                 type = KMALLOC_NO_OBJ_EXT;
         |                        ^~~~~~~~~~~~~~~~~~
   In file included from mm/slub.c:55:
>> mm/internal.h:838:26: warning: implicit conversion from 'unsigned long long' to 'u32' (aka 'unsigned int') changes value from 17179869184 to 0 [-Wconstant-conversion]
     838 |         VM_WARN_ON_ONCE(order > MAX_FOLIO_ORDER);
         |                                 ^~~~~~~~~~~~~~~
   include/linux/mmzone.h:85:33: note: expanded from macro 'MAX_FOLIO_ORDER'
      85 | #define MAX_FOLIO_ORDER         (ilog2(SZ_16G) - PAGE_SHIFT)
         |                                  ~~~~~~^~~~~~~
   include/linux/sizes.h:56:19: note: expanded from macro 'SZ_16G'
      56 | #define SZ_16G                          _AC(0x400000000, ULL)
         |                                         ^~~~~~~~~~~~~~~~~~~~~
   include/uapi/linux/const.h:21:18: note: expanded from macro '_AC'
      21 | #define _AC(X,Y)        __AC(X,Y)
         |                         ^~~~~~~~~
   note: (skipping 2 expansions in backtrace; use -fmacro-backtrace-limit=0 to see all)
   include/linux/log2.h:162:14: note: expanded from macro 'ilog2'
     162 |         __ilog2_u32(n) :                \
         |         ~~~~~~~~~~~ ^
   include/linux/mmdebug.h:123:50: note: expanded from macro 'VM_WARN_ON_ONCE'
     123 | #define VM_WARN_ON_ONCE(cond) (void)WARN_ON_ONCE(cond)
         |                                                  ^~~~
   include/asm-generic/bug.h:120:25: note: expanded from macro 'WARN_ON_ONCE'
     120 |         int __ret_warn_on = !!(condition);                              \
         |                                ^~~~~~~~~
   1 warning and 1 error generated.


vim +838 mm/internal.h

904d58578fce531 Kefeng Wang             2023-05-16  822  
3c605096d315821 Joonsoo Kim             2014-11-13  823  extern int __isolate_free_page(struct page *page, unsigned int order);
624f58d8f463967 Alexander Duyck         2020-04-06  824  extern void __putback_isolated_page(struct page *page, unsigned int order,
624f58d8f463967 Alexander Duyck         2020-04-06  825  				    int mt);
58e3e5265484a1b Shengming Hu            2025-12-29  826  extern void memblock_free_pages(unsigned long pfn, unsigned int order);
13c526540b31693 David Hildenbrand       2024-06-07  827  extern void __free_pages_core(struct page *page, unsigned int order,
13c526540b31693 David Hildenbrand       2024-06-07  828  		enum meminit_context context);
9420f89db2dd611 Mike Rapoport (IBM      2023-03-21  829) 
1e3be4856f49d55 Tarun Sahu              2023-06-12  830  /*
1e3be4856f49d55 Tarun Sahu              2023-06-12  831   * This will have no effect, other than possibly generating a warning, if the
1e3be4856f49d55 Tarun Sahu              2023-06-12  832   * caller passes in a non-large folio.
1e3be4856f49d55 Tarun Sahu              2023-06-12  833   */
1e3be4856f49d55 Tarun Sahu              2023-06-12  834  static inline void folio_set_order(struct folio *folio, unsigned int order)
1e3be4856f49d55 Tarun Sahu              2023-06-12  835  {
1e3be4856f49d55 Tarun Sahu              2023-06-12  836  	if (WARN_ON_ONCE(!order || !folio_test_large(folio)))
1e3be4856f49d55 Tarun Sahu              2023-06-12  837  		return;
99132d24d76511f David Hildenbrand       2025-09-01 @838  	VM_WARN_ON_ONCE(order > MAX_FOLIO_ORDER);
1e3be4856f49d55 Tarun Sahu              2023-06-12  839  
ebc1baf5c9b46c2 Matthew Wilcox (Oracle  2023-08-16  840) 	folio->_flags_1 = (folio->_flags_1 & ~0xffUL) | order;
4996fc547f5b49f David Hildenbrand       2025-03-03  841  #ifdef NR_PAGES_IN_LARGE_FOLIO
4996fc547f5b49f David Hildenbrand       2025-03-03  842  	folio->_nr_pages = 1U << order;
1e3be4856f49d55 Tarun Sahu              2023-06-12  843  #endif
1e3be4856f49d55 Tarun Sahu              2023-06-12  844  }
1e3be4856f49d55 Tarun Sahu              2023-06-12  845  

:::::: The code at line 838 was first introduced by commit
:::::: 99132d24d76511f0f6ded2e25448765b632794aa mm: sanity-check maximum folio size in folio_set_order()

:::::: TO: David Hildenbrand <david@redhat.com>
:::::: CC: Andrew Morton <akpm@linux-foundation.org>

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