Re: [PATCH bpf-next 1/4] bpf: arena: populate vm_area without allocating memory

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

Hi Puranjay,

kernel test robot noticed the following build warnings:

[auto build test WARNING on bpf-next/master]

url:    https://github.com/intel-lab-lkp/linux/commits/Puranjay-Mohan/bpf-arena-populate-vm_area-without-allocating-memory/20251112-004253
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
patch link:    https://lore.kernel.org/r/20251111163424.16471-2-puranjay%40kernel.org
patch subject: [PATCH bpf-next 1/4] bpf: arena: populate vm_area without allocating memory
config: arm64-randconfig-003-20251112 (https://download.01.org/0day-ci/archive/20251113/202511130329.jSq8tSKf-lkp@intel.com/config)
compiler: aarch64-linux-gcc (GCC) 8.5.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20251113/202511130329.jSq8tSKf-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/202511130329.jSq8tSKf-lkp@intel.com/

All warnings (new ones prefixed by >>):

   kernel/bpf/arena.c: In function 'apply_range_clear_cb':
>> kernel/bpf/arena.c:122:20: warning: unused variable 'mm' [-Wunused-variable]
     struct mm_struct *mm = &init_mm;
                       ^~


vim +/mm +122 kernel/bpf/arena.c

   119	
   120	static int apply_range_clear_cb(pte_t *pte, unsigned long addr, void *data)
   121	{
 > 122		struct mm_struct *mm = &init_mm;
   123		pte_t old_pte;
   124		struct page *page;
   125	
   126		/* sanity check */
   127		old_pte = ptep_get(pte);
   128		if (pte_none(old_pte) || !pte_present(old_pte))
   129			return 0; /* nothing to do */
   130	
   131		/* get page and free it */
   132		page = pte_page(old_pte);
   133		if (WARN_ON_ONCE(!page))
   134			return -EINVAL;
   135	
   136		pte_clear(mm, addr, pte);
   137	
   138		/* ensure no stale TLB entries */
   139		flush_tlb_kernel_range(addr, addr + PAGE_SIZE);
   140	
   141		__free_page(page);
   142	
   143		return 0;
   144	}
   145	

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