[akpm-mm:mm-unstable 102/221] include/linux/pgtable.h:2000:17: error: implicit declaration of function 'VM_WARN_ON_ONCE'; did you mean 'WARN_ON_ONCE'?

[akpm-mm:mm-unstable 102/221] include/linux/pgtable.h:2000:17: error: implicit declaration of function 'VM_WARN_ON_ONCE'; did you mean 'WARN_ON_ONCE'?

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable
head:   3c3393d4b766eebdc475ea5bd6bbd3a221e2526e
commit: d2e502b0fe1166f68c7ca5815e73ad12bf87e74d [102/221] mm/memory: convert print_bad_pte() to print_bad_page_map()
config: xtensa-nommu_kc705_defconfig (https://download.01.org/0day-ci/archive/20250825/202508250425.yEOYgcC5-lkp@intel.com/config)
compiler: xtensa-linux-gcc (GCC) 15.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250825/202508250425.yEOYgcC5-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/202508250425.yEOYgcC5-lkp@intel.com/

All errors (new ones prefixed by >>):

   In file included from arch/xtensa/include/asm/io.h:19,
                    from include/linux/io.h:12,
                    from lib/iomem_copy.c:8:
   include/linux/pgtable.h: In function 'pgtable_level_to_str':
>> include/linux/pgtable.h:2000:17: error: implicit declaration of function 'VM_WARN_ON_ONCE'; did you mean 'WARN_ON_ONCE'? [-Wimplicit-function-declaration]
    2000 |                 VM_WARN_ON_ONCE(1);
         |                 ^~~~~~~~~~~~~~~
         |                 WARN_ON_ONCE


vim +2000 include/linux/pgtable.h

  1985	
  1986	static inline const char *pgtable_level_to_str(enum pgtable_level level)
  1987	{
  1988		switch (level) {
  1989		case PGTABLE_LEVEL_PTE:
  1990			return "pte";
  1991		case PGTABLE_LEVEL_PMD:
  1992			return "pmd";
  1993		case PGTABLE_LEVEL_PUD:
  1994			return "pud";
  1995		case PGTABLE_LEVEL_P4D:
  1996			return "p4d";
  1997		case PGTABLE_LEVEL_PGD:
  1998			return "pgd";
  1999		default:
> 2000			VM_WARN_ON_ONCE(1);
  2001			return "unknown";
  2002		}
  2003	}
  2004	

-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [akpm-mm:mm-unstable 102/221] include/linux/pgtable.h:2000:17: error: implicit declaration of function 'VM_WARN_ON_ONCE'; did you mean 'WARN_ON_ONCE'?

[David Hildenbrand]

On 24.08.25 22:10, kernel test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable
> head:   3c3393d4b766eebdc475ea5bd6bbd3a221e2526e
> commit: d2e502b0fe1166f68c7ca5815e73ad12bf87e74d [102/221] mm/memory: convert print_bad_pte() to print_bad_page_map()
> config: xtensa-nommu_kc705_defconfig (https://download.01.org/0day-ci/archive/20250825/202508250425.yEOYgcC5-lkp@intel.com/config)
> compiler: xtensa-linux-gcc (GCC) 15.1.0
> reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250825/202508250425.yEOYgcC5-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/202508250425.yEOYgcC5-lkp@intel.com/
> 
> All errors (new ones prefixed by >>):
> 
>     In file included from arch/xtensa/include/asm/io.h:19,
>                      from include/linux/io.h:12,
>                      from lib/iomem_copy.c:8:
>     include/linux/pgtable.h: In function 'pgtable_level_to_str':
>>> include/linux/pgtable.h:2000:17: error: implicit declaration of function 'VM_WARN_ON_ONCE'; did you mean 'WARN_ON_ONCE'? [-Wimplicit-function-declaration]
>      2000 |                 VM_WARN_ON_ONCE(1);
>           |                 ^~~~~~~~~~~~~~~
>           |                 WARN_ON_ONCE
> 

The bot really had to try hard finding a config where that doesn't work :)

#syz test

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 9f0329d45b1e1..94249e671a7e8 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1997,7 +1997,6 @@ static inline const char 
*pgtable_level_to_str(enum pgtable_level level)
  	case PGTABLE_LEVEL_PGD:
  		return "pgd";
  	default:
-		VM_WARN_ON_ONCE(1);
  		return "unknown";
  	}
  }

-- 
Cheers

David / dhildenb