arch/s390/kernel/syscall.c:56:1: sparse: sparse: Using plain integer as NULL pointer

[kernel test robot]

Hi Sven,

First bad commit (maybe != root cause):

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   5f53fa508db098c9d372423a6dac31c8a5679cdf
commit: 56e62a73702836017564eaacd5212e4d0fa1c01d s390: convert to generic entry
date:   10 months ago
config: s390-randconfig-s031-20211116 (https://download.01.org/0day-ci/archive/20211125/202111252321.A2S8SwOA-lkp@xxxxxxxxx/config)
compiler: s390-linux-gcc (GCC) 11.2.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # apt-get install sparse
        # sparse version: v0.6.4-dirty
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=56e62a73702836017564eaacd5212e4d0fa1c01d
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout 56e62a73702836017564eaacd5212e4d0fa1c01d
        # save the config file to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=s390 SHELL=/bin/bash

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


sparse warnings: (new ones prefixed by >>)
>> arch/s390/kernel/syscall.c:56:1: sparse: sparse: Using plain integer as NULL pointer
>> arch/s390/kernel/syscall.c:56:1: sparse: sparse: Using plain integer as NULL pointer

vim +56 arch/s390/kernel/syscall.c

^1da177e4c3f415 arch/s390/kernel/sys_s390.c Linus Torvalds    2005-04-16  55  
a4679373cf4ee0e arch/s390/kernel/sys_s390.c Christoph Hellwig 2010-03-10 @56  SYSCALL_DEFINE1(mmap2, struct s390_mmap_arg_struct __user *, arg)
^1da177e4c3f415 arch/s390/kernel/sys_s390.c Linus Torvalds    2005-04-16  57  {
a4679373cf4ee0e arch/s390/kernel/sys_s390.c Christoph Hellwig 2010-03-10  58  	struct s390_mmap_arg_struct a;
^1da177e4c3f415 arch/s390/kernel/sys_s390.c Linus Torvalds    2005-04-16  59  	int error = -EFAULT;
^1da177e4c3f415 arch/s390/kernel/sys_s390.c Linus Torvalds    2005-04-16  60  
^1da177e4c3f415 arch/s390/kernel/sys_s390.c Linus Torvalds    2005-04-16  61  	if (copy_from_user(&a, arg, sizeof(a)))
^1da177e4c3f415 arch/s390/kernel/sys_s390.c Linus Torvalds    2005-04-16  62  		goto out;
a90f590a1bee36f arch/s390/kernel/sys_s390.c Dominik Brodowski 2018-03-11  63  	error = ksys_mmap_pgoff(a.addr, a.len, a.prot, a.flags, a.fd, a.offset);
^1da177e4c3f415 arch/s390/kernel/sys_s390.c Linus Torvalds    2005-04-16  64  out:
^1da177e4c3f415 arch/s390/kernel/sys_s390.c Linus Torvalds    2005-04-16  65  	return error;
^1da177e4c3f415 arch/s390/kernel/sys_s390.c Linus Torvalds    2005-04-16  66  }
^1da177e4c3f415 arch/s390/kernel/sys_s390.c Linus Torvalds    2005-04-16  67  

:::::: The code at line 56 was first introduced by commit
:::::: a4679373cf4ee0e7792dc56205365732b725c2c1 Add generic sys_old_mmap()

:::::: TO: Christoph Hellwig <hch@xxxxxx>
:::::: CC: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>

---
0-DAY CI Kernel Test Service, Intel Corporation
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