[davidhildenbrand:get_dummy 14/21] include/linux/pgtable.h:2351:13: error: implicit declaration of function 'mm_pmd_folded'

Hi Yeoreum,

FYI, the error/warning was bisected to this commit, please ignore it if it's irrelevant.

tree:   https://github.com/davidhildenbrand/linux get_dummy
head:   112a153a97494becabd764fe6257578ba908801f
commit: db92928e80f5332bbfca9a70beaef62d46a0c9de [14/21] x86: mm: carve out the generic compile-time folded pgtable case in effective_prot()
config: m68k-allnoconfig (https://download.01.org/0day-ci/archive/20260827/[email protected]/config)
compiler: m68k-linux-gcc (GCC) 16.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260827/[email protected]/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 <[email protected]>
| Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/

All errors (new ones prefixed by >>):

   In file included from include/linux/mm.h:31,
                    from include/linux/cpuset.h:17,
                    from kernel/sched/sched.h:33,
                    from kernel/sched/rq-offsets.c:5:
   include/linux/pgtable.h: In function 'mm_first_pgtable_level':
>> include/linux/pgtable.h:2351:13: error: implicit declaration of function 'mm_pmd_folded' [-Wimplicit-function-declaration]
    2351 |         if (mm_pmd_folded(mm))
         |             ^~~~~~~~~~~~~
>> include/linux/pgtable.h:2353:13: error: implicit declaration of function 'mm_pud_folded' [-Wimplicit-function-declaration]
    2353 |         if (mm_pud_folded(mm))
         |             ^~~~~~~~~~~~~
>> include/linux/pgtable.h:2355:13: error: implicit declaration of function 'mm_p4d_folded' [-Wimplicit-function-declaration]
    2355 |         if (mm_p4d_folded(mm))
         |             ^~~~~~~~~~~~~
   make[3]: *** [scripts/Makefile.build:184: kernel/sched/rq-offsets.s] Error 1
   make[3]: Target 'prepare' not remade because of errors.
   make[2]: *** [Makefile:1410: prepare0] Error 2
   make[2]: Target 'prepare' not remade because of errors.
   make[1]: *** [Makefile:248: __sub-make] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [Makefile:248: __sub-make] Error 2
   make: Target 'prepare' not remade because of errors.


vim +/mm_pmd_folded +2351 include/linux/pgtable.h

  2331	
  2332	/**
  2333	 * mm_first_pgtable_level - return the first non-folded page-table level
  2334	 * @mm: The mm structure.
  2335	 *
  2336	 * With runtime- or compile-time folded page tables, page-table walkers
  2337	 * effectively skip the folded top-level page tables, treating them as
  2338	 * always-present entries pointing to the next lower-level page table.
  2339	 *
  2340	 * Return the first page-table level in @mm that is not folded.
  2341	 *
  2342	 * Return: the first non-folded page-table level.
  2343	 */
  2344	static inline enum pgtable_level mm_first_pgtable_level(struct mm_struct *mm)
  2345	{
  2346		/*
  2347		 * "PMD folded" actually means "PMD is folded into PUD", and
  2348		 * pud_present() etc. are hard-coded to look like present page table
  2349		 * levels, whereby pmd_present() etc. contain real logic.
  2350		 */
> 2351		if (mm_pmd_folded(mm))
  2352			return PGTABLE_LEVEL_PMD;
> 2353		if (mm_pud_folded(mm))
  2354			return PGTABLE_LEVEL_PUD;
> 2355		if (mm_p4d_folded(mm))
  2356			return PGTABLE_LEVEL_P4D;
  2357		return PGTABLE_LEVEL_PGD;
  2358	}
  2359	

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