Re: [PATCH 3/4] mm: khugepaged: move mm to list tail when MADV_COLD/MADV_FREE

[kernel test robot]

Hi Vernon,

kernel test robot noticed the following build errors:

[auto build test ERROR on akpm-mm/mm-everything]
[also build test ERROR on linus/master v6.19-rc1 next-20251216]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Vernon-Yang/mm-khugepaged-add-trace_mm_khugepaged_scan-event/20251215-171046
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20251215090419.174418-4-yanglincheng%40kylinos.cn
patch subject: [PATCH 3/4] mm: khugepaged: move mm to list tail when MADV_COLD/MADV_FREE
config: x86_64-kexec (https://download.01.org/0day-ci/archive/20251216/202512161406.RfF1dIYB-lkp@xxxxxxxxx/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251216/202512161406.RfF1dIYB-lkp@xxxxxxxxx/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@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202512161406.RfF1dIYB-lkp@xxxxxxxxx/

All errors (new ones prefixed by >>):

>> mm/madvise.c:609:2: error: call to undeclared function 'khugepaged_move_tail'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     609 |         khugepaged_move_tail(vma->vm_mm);
         |         ^
   mm/madvise.c:837:2: error: call to undeclared function 'khugepaged_move_tail'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     837 |         khugepaged_move_tail(mm);
         |         ^
   2 errors generated.


vim +/khugepaged_move_tail +609 mm/madvise.c

   595	
   596	static long madvise_cold(struct madvise_behavior *madv_behavior)
   597	{
   598		struct vm_area_struct *vma = madv_behavior->vma;
   599		struct mmu_gather tlb;
   600	
   601		if (!can_madv_lru_vma(vma))
   602			return -EINVAL;
   603	
   604		lru_add_drain();
   605		tlb_gather_mmu(&tlb, madv_behavior->mm);
   606		madvise_cold_page_range(&tlb, madv_behavior);
   607		tlb_finish_mmu(&tlb);
   608	
 > 609		khugepaged_move_tail(vma->vm_mm);
   610	
   611		return 0;
   612	}
   613	

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