Hi Zi,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on kselftest/next]
[also build test WARNING on linux/master linus/master v5.12-rc3]
[cannot apply to hnaz-linux-mm/master next-20210315]
[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]

url:    https://github.com/0day-ci/linux/commits/Zi-Yan/mm-huge_memory-a-new-debugfs-interface-for-splitting-THP-tests/20210316-043528
base:   https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git next
config: i386-randconfig-m021-20210315 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0

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

smatch warnings:
mm/huge_memory.c:3086 split_huge_pages_write() warn: sscanf doesn't return error codes

vim +3086 mm/huge_memory.c

  3051	
  3052	static ssize_t split_huge_pages_write(struct file *file, const char __user *buf,
  3053					size_t count, loff_t *ppops)
  3054	{
  3055		static DEFINE_MUTEX(mutex);
  3056		ssize_t ret;
  3057		char input_buf[80]; /* hold pid, start_vaddr, end_vaddr */
  3058		int pid;
  3059		unsigned long vaddr_start, vaddr_end;
  3060	
  3061		ret = mutex_lock_interruptible(&mutex);
  3062		if (ret)
  3063			return ret;
  3064	
  3065		ret = -EFAULT;
  3066	
  3067		memset(input_buf, 0, 80);
  3068		if (copy_from_user(input_buf, buf, min_t(size_t, count, 80)))
  3069			goto out;
  3070	
  3071		input_buf[79] = '\0';
  3072		ret = sscanf(input_buf, "%d,0x%lx,0x%lx", &pid, &vaddr_start, &vaddr_end);
  3073		if (ret == 1 && pid == 1) {
  3074			split_huge_pages_all();
  3075			ret = strlen(input_buf);
  3076			goto out;
  3077		} else if (ret != 3) {
  3078			ret = -EINVAL;
  3079			goto out;
  3080		}
  3081	
  3082		if (!split_huge_pages_pid(pid, vaddr_start, vaddr_end))
  3083			ret = strlen(input_buf);
  3084	out:
  3085		mutex_unlock(&mutex);
> 3086		return ret;
  3087	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org