[akpm-mm:mm-unstable 25/274] mm/hugetlb.c:7281:3: error: call to undeclared function '__huge_pmd_unshare'; ISO C99 and later do not support implicit function declarations

[kernel test robot <lkp@intel.com>]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable
head:   444fc9435e57157fcf30fc99aee44997f3458641
commit: 2bb8fe16f7bf4487248c9ff847fcf189c45b9508 [25/274] mm/hugetlb: avoid false positive lockdep assertion
config: powerpc64-randconfig-001-20260514 (https://download.01.org/0day-ci/archive/20260514/202605141638.b5ZBd6IF-lkp@intel.com/config)
compiler: clang version 23.0.0git (https://github.com/llvm/llvm-project 5bac06718f502014fade905512f1d26d578a18f3)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260514/202605141638.b5ZBd6IF-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/202605141638.b5ZBd6IF-lkp@intel.com/

All errors (new ones prefixed by >>):

>> mm/hugetlb.c:7281:3: error: call to undeclared function '__huge_pmd_unshare'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
    7281 |                 __huge_pmd_unshare(&tlb, vma, address, ptep, take_locks);
         |                 ^
   mm/hugetlb.c:7281:3: note: did you mean 'huge_pmd_unshare'?
   mm/hugetlb.c:6973:5: note: 'huge_pmd_unshare' declared here
    6973 | int huge_pmd_unshare(struct mmu_gather *tlb, struct vm_area_struct *vma,
         |     ^
   1 error generated.


vim +/__huge_pmd_unshare +7281 mm/hugetlb.c

  7233	
  7234	/*
  7235	 * If @take_locks is false, the caller must ensure that no concurrent page table
  7236	 * access can happen (except for gup_fast() and hardware page walks).
  7237	 * If @take_locks is true, we take the hugetlb VMA lock (to lock out things like
  7238	 * concurrent page fault handling) and the file rmap lock.
  7239	 */
  7240	static void hugetlb_unshare_pmds(struct vm_area_struct *vma,
  7241					   unsigned long start,
  7242					   unsigned long end,
  7243					   bool take_locks)
  7244	{
  7245		struct hstate *h = hstate_vma(vma);
  7246		unsigned long sz = huge_page_size(h);
  7247		struct mm_struct *mm = vma->vm_mm;
  7248		struct mmu_notifier_range range;
  7249		struct mmu_gather tlb;
  7250		unsigned long address;
  7251		spinlock_t *ptl;
  7252		pte_t *ptep;
  7253	
  7254		if (!(vma->vm_flags & VM_MAYSHARE))
  7255			return;
  7256	
  7257		if (start >= end)
  7258			return;
  7259	
  7260		flush_cache_range(vma, start, end);
  7261		tlb_gather_mmu_vma(&tlb, vma);
  7262	
  7263		/*
  7264		 * No need to call adjust_range_if_pmd_sharing_possible(), because
  7265		 * we have already done the PUD_SIZE alignment.
  7266		 */
  7267		mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, mm,
  7268					start, end);
  7269		mmu_notifier_invalidate_range_start(&range);
  7270		if (take_locks) {
  7271			hugetlb_vma_lock_write(vma);
  7272			i_mmap_lock_write(vma->vm_file->f_mapping);
  7273		} else {
  7274			i_mmap_assert_write_locked(vma->vm_file->f_mapping);
  7275		}
  7276		for (address = start; address < end; address += PUD_SIZE) {
  7277			ptep = hugetlb_walk(vma, address, sz);
  7278			if (!ptep)
  7279				continue;
  7280			ptl = huge_pte_lock(h, mm, ptep);
> 7281			__huge_pmd_unshare(&tlb, vma, address, ptep, take_locks);
  7282			spin_unlock(ptl);
  7283		}
  7284		huge_pmd_unshare_flush(&tlb, vma);
  7285		if (take_locks) {
  7286			i_mmap_unlock_write(vma->vm_file->f_mapping);
  7287			hugetlb_vma_unlock_write(vma);
  7288		}
  7289		/*
  7290		 * No need to call mmu_notifier_arch_invalidate_secondary_tlbs(), see
  7291		 * Documentation/mm/mmu_notifier.rst.
  7292		 */
  7293		mmu_notifier_invalidate_range_end(&range);
  7294		tlb_finish_mmu(&tlb);
  7295	}
  7296	

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