Re: [PATCH v10 2/3] cachestat: implement cachestat syscall

[kernel test robot]

Hi Nhat,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on 1440f576022887004f719883acb094e7e0dd4944]

url:    https://github.com/intel-lab-lkp/linux/commits/Nhat-Pham/workingset-refactor-LRU-refault-to-expose-refault-recency-check/20230219-153500
base:   1440f576022887004f719883acb094e7e0dd4944
patch link:    https://lore.kernel.org/r/20230219073318.366189-3-nphamcs%40gmail.com
patch subject: [PATCH v10 2/3] cachestat: implement cachestat syscall
config: i386-randconfig-a001 (https://download.01.org/0day-ci/archive/20230219/202302191804.5m2GB1PU-lkp@xxxxxxxxx/config)
compiler: gcc-11 (Debian 11.3.0-8) 11.3.0
reproduce (this is a W=1 build):
        # https://github.com/intel-lab-lkp/linux/commit/d691a3b4a696ab20c9c5fe86c624e9e36814523c
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Nhat-Pham/workingset-refactor-LRU-refault-to-expose-refault-recency-check/20230219-153500
        git checkout d691a3b4a696ab20c9c5fe86c624e9e36814523c
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Link: https://lore.kernel.org/oe-kbuild-all/202302191804.5m2GB1PU-lkp@xxxxxxxxx/

All warnings (new ones prefixed by >>):

>> mm/filemap.c:4035:6: warning: no previous prototype for 'ksys_cachestat' [-Wmissing-prototypes]
    4035 | long ksys_cachestat(unsigned int fd, size_t len, loff_t off,
         |      ^~~~~~~~~~~~~~


vim +/ksys_cachestat +4035 mm/filemap.c

  4033	
  4034	#ifdef CONFIG_CACHESTAT_SYSCALL
> 4035	long ksys_cachestat(unsigned int fd, size_t len, loff_t off,
  4036			struct cachestat __user *cstat, unsigned int flags)
  4037	{
  4038		struct fd f = fdget(fd);
  4039		struct address_space *mapping;
  4040		struct cachestat cs;
  4041		pgoff_t first_index = off >> PAGE_SHIFT;
  4042		pgoff_t last_index =
  4043			len == 0 ? ULONG_MAX : (off + len - 1) >> PAGE_SHIFT;
  4044	
  4045		if (!f.file)
  4046			return -EBADF;
  4047	
  4048		if (off < 0 || flags != 0) {
  4049			fdput(f);
  4050			return -EINVAL;
  4051		}
  4052	
  4053		memset(&cs, 0, sizeof(struct cachestat));
  4054		mapping = f.file->f_mapping;
  4055		filemap_cachestat(mapping, first_index, last_index, &cs);
  4056		fdput(f);
  4057	
  4058		if (copy_to_user(cstat, &cs, sizeof(struct cachestat)))
  4059			return -EFAULT;
  4060	
  4061		return 0;
  4062	}
  4063	

-- 
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https://github.com/intel/lkp-tests