Re: [PATCH] mm, hugetlb: Reset mapping to TAIL_MAPPING before restoring vmemmap

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

Hi Oscar,

kernel test robot noticed the following build errors:

[auto build test ERROR on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/Oscar-Salvador/mm-hugetlb-Reset-mapping-to-TAIL_MAPPING-before-restoring-vmemmap/20250415-134835
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20250415054705.370412-1-osalvador%40suse.de
patch subject: [PATCH] mm, hugetlb: Reset mapping to TAIL_MAPPING before restoring vmemmap
config: x86_64-buildonly-randconfig-006-20250416 (https://download.01.org/0day-ci/archive/20250416/202504161522.S1qEFD4b-lkp@intel.com/config)
compiler: clang version 20.1.2 (https://github.com/llvm/llvm-project 58df0ef89dd64126512e4ee27b4ac3fd8ddf6247)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250416/202504161522.S1qEFD4b-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/202504161522.S1qEFD4b-lkp@intel.com/

All errors (new ones prefixed by >>):

>> mm/hugetlb_vmemmap.c:506:2: error: call to undeclared function 'set_hugetlb_cgroup'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
     506 |         set_hugetlb_cgroup(folio, TAIL_MAPPING);
         |         ^
   1 error generated.


vim +/set_hugetlb_cgroup +506 mm/hugetlb_vmemmap.c

   488	
   489	/**
   490	 * hugetlb_vmemmap_restore_folio - restore previously optimized (by
   491	 *				hugetlb_vmemmap_optimize_folio()) vmemmap pages which
   492	 *				will be reallocated and remapped.
   493	 * @h:		struct hstate.
   494	 * @folio:     the folio whose vmemmap pages will be restored.
   495	 *
   496	 * Return: %0 if @folio's vmemmap pages have been reallocated and remapped,
   497	 * negative error code otherwise.
   498	 */
   499	int hugetlb_vmemmap_restore_folio(const struct hstate *h, struct folio *folio)
   500	{
   501		/*
   502		 * Before restoring vmemmap, make sure to reset mapping to TAIL_MAPPING,
   503		 * so tail pages that were reset will have the right thing after being
   504		 * restored, and the checks in free_tail_page_prepare() will pass.
   505		 */
 > 506		set_hugetlb_cgroup(folio, TAIL_MAPPING);
   507		return __hugetlb_vmemmap_restore_folio(h, folio, VMEMMAP_SYNCHRONIZE_RCU);
   508	}
   509	

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