linux-kernel - [rcu:willy-maple 189/202] mm/mmap.c:2830:18: warning: variable 'ma

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Date:   Wed, 3 Feb 2021 11:07:46 +0800
From:   kernel test robot <lkp@...el.com>
To:     "Liam R. Howlett" <Liam.Howlett@...cle.com>
Cc:     kbuild-all@...ts.01.org, linux-kernel@...r.kernel.org
Subject: [rcu:willy-maple 189/202] mm/mmap.c:2830:18: warning: variable
 'ma_lock' set but not used

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git willy-maple
head:   7e346d2845b4bd77663394f39fa70456e0084c86
commit: e40a951e09ed0e66dbd646f938df19c876915b9d [189/202] mm: Remove vma linked list.
config: alpha-defconfig (attached as .config)
compiler: alpha-linux-gcc (GCC) 9.3.0
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://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git/commit/?id=e40a951e09ed0e66dbd646f938df19c876915b9d
        git remote add rcu https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git
        git fetch --no-tags rcu willy-maple
        git checkout e40a951e09ed0e66dbd646f938df19c876915b9d
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=alpha 

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

All warnings (new ones prefixed by >>):

   mm/mmap.c:2366:5: warning: no previous prototype for 'do_mas_align_munmap' [-Wmissing-prototypes]
    2366 | int do_mas_align_munmap(struct ma_state *mas, struct vm_area_struct *vma,
         |     ^~~~~~~~~~~~~~~~~~~
   mm/mmap.c: In function '__do_sys_remap_file_pages':
>> mm/mmap.c:2830:18: warning: variable 'ma_lock' set but not used [-Wunused-but-set-variable]
    2830 |  struct ma_state ma_lock;
         |                  ^~~~~~~


vim +/ma_lock +2830 mm/mmap.c

  2824	
  2825		struct mm_struct *mm = current->mm;
  2826		struct vm_area_struct *vma;
  2827		unsigned long populate = 0;
  2828		unsigned long ret = -EINVAL;
  2829		struct file *file;
> 2830		struct ma_state ma_lock;
  2831		MA_STATE(mas, &mm->mm_mt, start, start);
  2832	
  2833		pr_warn_once("%s (%d) uses deprecated remap_file_pages() syscall. See Documentation/vm/remap_file_pages.rst.\n",
  2834			     current->comm, current->pid);
  2835	
  2836		if (prot)
  2837			return ret;
  2838	
  2839		start = start & PAGE_MASK;
  2840		size = size & PAGE_MASK;
  2841		if (start + size <= start)
  2842			return ret;
  2843	
  2844		/* Does pgoff wrap? */
  2845		if (pgoff + (size >> PAGE_SHIFT) < pgoff)
  2846			return ret;
  2847	
  2848		if (mmap_write_lock_killable(mm))
  2849			return -EINTR;
  2850	
  2851		mas_set(&mas, start);
  2852		vma = mas_walk(&mas);
  2853		ma_lock = mas;
  2854	
  2855		if (!vma || !(vma->vm_flags & VM_SHARED))
  2856			goto out;
  2857	
  2858		if (!vma->vm_file)
  2859			goto out;
  2860	
  2861		if (start + size > vma->vm_end) {
  2862			struct vm_area_struct *prev, *next;
  2863	
  2864			prev = vma;
  2865			mas_for_each(&mas, next, start + size) {
  2866				/* hole between vmas ? */
  2867				if (next->vm_start != prev->vm_end)
  2868					goto out;
  2869	
  2870				if (next->vm_file != vma->vm_file)
  2871					goto out;
  2872	
  2873				if (next->vm_flags != vma->vm_flags)
  2874					goto out;
  2875	
  2876				if (start + size <= next->vm_end)
  2877					break;
  2878	
  2879				prev = next;
  2880			}
  2881	
  2882			if (!next)
  2883				goto out;
  2884		}
  2885	
  2886		prot |= vma->vm_flags & VM_READ ? PROT_READ : 0;
  2887		prot |= vma->vm_flags & VM_WRITE ? PROT_WRITE : 0;
  2888		prot |= vma->vm_flags & VM_EXEC ? PROT_EXEC : 0;
  2889	
  2890		flags &= MAP_NONBLOCK;
  2891		flags |= MAP_SHARED | MAP_FIXED | MAP_POPULATE;
  2892	
  2893		file = get_file(vma->vm_file);
  2894		ret = do_mmap(vma->vm_file, start, size,
  2895				prot, flags, pgoff, &populate, NULL);
  2896		fput(file);
  2897	out:
  2898		mmap_write_unlock(mm);
  2899		if (populate)
  2900			mm_populate(ret, populate);
  2901		if (!IS_ERR_VALUE(ret))
  2902			ret = 0;
  2903		return ret;
  2904	}
  2905	

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

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