Re: [PATCH v11 2/3] cachestat: implement cachestat syscall

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

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/20230308-112932
base:   1440f576022887004f719883acb094e7e0dd4944
patch link:    https://lore.kernel.org/r/20230308032748.609510-3-nphamcs%40gmail.com
patch subject: [PATCH v11 2/3] cachestat: implement cachestat syscall
config: arm-randconfig-r046-20230308 (https://download.01.org/0day-ci/archive/20230309/202303092111.mhDcYB71-lkp@intel.com/config)
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/ca34a4daf11f6fbb9731205af7acd06fe620e447
        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/20230308-112932
        git checkout ca34a4daf11f6fbb9731205af7acd06fe620e447
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-12.1.0 make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash kernel/bpf/ mm/ prepare

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>
| Link: https://lore.kernel.org/oe-kbuild-all/202303092111.mhDcYB71-lkp@intel.com/

All warnings (new ones prefixed by >>):

>> <stdin>:1565:2: warning: #warning syscall cachestat not implemented [-Wcpp]
--
   In file included from include/linux/filter.h:11,
                    from include/linux/bpf_verifier.h:9,
                    from tools/lib/bpf/relo_core.c:8:
>> include/linux/compat.h:821:45: warning: 'struct cachestat' declared inside parameter list will not be visible outside of this definition or declaration
     821 |                 compat_arg_u64(off), struct cachestat __user *cstat,
         |                                             ^~~~~~~~~
--
   In file included from include/linux/filter.h:11,
                    from kernel/bpf/core.c:21:
>> include/linux/compat.h:821:45: warning: 'struct cachestat' declared inside parameter list will not be visible outside of this definition or declaration
     821 |                 compat_arg_u64(off), struct cachestat __user *cstat,
         |                                             ^~~~~~~~~
   kernel/bpf/core.c:1628:12: warning: no previous prototype for 'bpf_probe_read_kernel' [-Wmissing-prototypes]
    1628 | u64 __weak bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr)
         |            ^~~~~~~~~~~~~~~~~~~~~
--
   In file included from include/linux/filter.h:11,
                    from include/linux/bpf_verifier.h:9,
                    from kernel/bpf/btf.c:19:
>> include/linux/compat.h:821:45: warning: 'struct cachestat' declared inside parameter list will not be visible outside of this definition or declaration
     821 |                 compat_arg_u64(off), struct cachestat __user *cstat,
         |                                             ^~~~~~~~~
   kernel/bpf/btf.c: In function 'btf_seq_show':
   kernel/bpf/btf.c:6786:29: warning: function 'btf_seq_show' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]
    6786 |         seq_vprintf((struct seq_file *)show->target, fmt, args);
         |                             ^~~~~~~~
   kernel/bpf/btf.c: In function 'btf_snprintf_show':
   kernel/bpf/btf.c:6823:9: warning: function 'btf_snprintf_show' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]
    6823 |         len = vsnprintf(show->target, ssnprintf->len_left, fmt, args);
         |         ^~~
--
>> mm/filemap.c:4034:6: warning: no previous prototype for 'ksys_cachestat' [-Wmissing-prototypes]
    4034 | long ksys_cachestat(unsigned int fd, size_t len, loff_t off,
         |      ^~~~~~~~~~~~~~
--
>> <stdin>:1565:2: warning: #warning syscall cachestat not implemented [-Wcpp]
--
>> <stdin>:1565:2: warning: #warning syscall cachestat not implemented [-Wcpp]


vim +821 include/linux/compat.h

   809	
   810	/* net/socket.c */
   811	asmlinkage long compat_sys_recvfrom(int fd, void __user *buf, compat_size_t len,
   812				    unsigned flags, struct sockaddr __user *addr,
   813				    int __user *addrlen);
   814	asmlinkage long compat_sys_sendmsg(int fd, struct compat_msghdr __user *msg,
   815					   unsigned flags);
   816	asmlinkage long compat_sys_recvmsg(int fd, struct compat_msghdr __user *msg,
   817					   unsigned int flags);
   818	
   819	/* mm/filemap.c */
   820	asmlinkage long compat_sys_cachestat(unsigned int fd, size_t len,
 > 821			compat_arg_u64(off), struct cachestat __user *cstat,
   822			unsigned int flags);
   823	

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