Hi Baoquan,

I love your patch! Perhaps something to improve:

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

url:    https://github.com/intel-lab-lkp/linux/commits/Baoquan-He/mm-vmalloc-c-allow-vread-to-read-out-vm_map_ram-areas/20221204-093322
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/20221204013046.154960-4-bhe%40redhat.com
patch subject: [PATCH v1 3/7] mm/vmalloc.c: allow vread() to read out vm_map_ram areas
config: arm-randconfig-r046-20221204
compiler: arm-linux-gnueabi-gcc (GCC) 12.1.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/intel-lab-lkp/linux/commit/0bcc4ce1e46418b86eb569175879081116649727
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Baoquan-He/mm-vmalloc-c-allow-vread-to-read-out-vm_map_ram-areas/20221204-093322
        git checkout 0bcc4ce1e46418b86eb569175879081116649727
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   mm/vmalloc.c: In function 'vb_vread':
>> mm/vmalloc.c:3540:23: warning: variable 'offset' set but not used [-Wunused-but-set-variable]
    3540 |         unsigned long offset;
         |                       ^~~~~~


vim +/offset +3540 mm/vmalloc.c

  3535	
  3536	static void vb_vread(char *buf, char *addr, int count)
  3537	{
  3538		char *start;
  3539		struct vmap_block *vb;
> 3540		unsigned long offset;
  3541		unsigned int rs, re, n;
  3542	
  3543		offset = ((unsigned long)addr & (VMAP_BLOCK_SIZE - 1)) >> PAGE_SHIFT;
  3544		vb = xa_load(&vmap_blocks, addr_to_vb_idx((unsigned long)addr));
  3545	
  3546		spin_lock(&vb->lock);
  3547		if (bitmap_empty(vb->used_map, VMAP_BBMAP_BITS)) {
  3548			spin_unlock(&vb->lock);
  3549			memset(buf, 0, count);
  3550			return;
  3551		}
  3552		for_each_set_bitrange(rs, re, vb->used_map, VMAP_BBMAP_BITS) {
  3553			if (!count)
  3554				break;
  3555			start = vmap_block_vaddr(vb->va->va_start, rs);
  3556			if (addr < start) {
  3557				if (count == 0)
  3558					break;
  3559				*buf = '\0';
  3560				buf++;
  3561				addr++;
  3562				count--;
  3563			}
  3564			n = (re - rs + 1) << PAGE_SHIFT;
  3565			if (n > count)
  3566				n = count;
  3567			aligned_vread(buf, start, n);
  3568	
  3569			buf += n;
  3570			addr += n;
  3571			count -= n;
  3572		}
  3573		spin_unlock(&vb->lock);
  3574	}
  3575	

-- 
0-DAY CI Kernel Test Service
https://01.org/lkp