[gfs2:for-next.holder_stealing2 5/13] mm/gup.c:1753:10: warning: comparison of distinct pointer types ('typeof (nstart - start) *' (aka 'unsigned long *') and 'typeof (size) *' (aka 'unsigned int *'))

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2.git for-next.holder_stealing2
head:   6af2ffaed52783f15505255e62c43d2083a4a3a2
commit: 14d6ca0628042b7be9c06df73fef131d3a98473a [5/13] iov_iter: Introduce fault_in_iov_iter_writeable
config: hexagon-randconfig-r005-20210804 (attached as .config)
compiler: clang version 12.0.0
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/gfs2/linux-gfs2.git/commit/?id=14d6ca0628042b7be9c06df73fef131d3a98473a
        git remote add gfs2 https://git.kernel.org/pub/scm/linux/kernel/git/gfs2/linux-gfs2.git
        git fetch --no-tags gfs2 for-next.holder_stealing2
        git checkout 14d6ca0628042b7be9c06df73fef131d3a98473a
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=hexagon 

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

All warnings (new ones prefixed by >>):

>> mm/gup.c:1753:10: warning: comparison of distinct pointer types ('typeof (nstart - start) *' (aka 'unsigned long *') and 'typeof (size) *' (aka 'unsigned int *')) [-Wcompare-distinct-pointer-types]
                   return min(nstart - start, size);
                          ^~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/minmax.h:45:19: note: expanded from macro 'min'
   #define min(x, y)       __careful_cmp(x, y, <)
                           ^~~~~~~~~~~~~~~~~~~~~~
   include/linux/minmax.h:36:24: note: expanded from macro '__careful_cmp'
           __builtin_choose_expr(__safe_cmp(x, y), \
                                 ^~~~~~~~~~~~~~~~
   include/linux/minmax.h:26:4: note: expanded from macro '__safe_cmp'
                   (__typecheck(x, y) && __no_side_effects(x, y))
                    ^~~~~~~~~~~~~~~~~
   include/linux/minmax.h:20:28: note: expanded from macro '__typecheck'
           (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1)))
                      ~~~~~~~~~~~~~~ ^  ~~~~~~~~~~~~~~
   1 warning generated.


vim +1753 mm/gup.c

  1696	
  1697	/**
  1698	 * fault_in_safe_writeable - fault in an address range for writing
  1699	 * @uaddr: start of address range
  1700	 * @size: length of address range
  1701	 *
  1702	 * Faults in an address range using get_user_pages, i.e., without triggering
  1703	 * hardware page faults.  This is primarily useful when we know that some or
  1704	 * all of the pages in the address range aren't in memory.
  1705	 *
  1706	 * Other than fault_in_writeable(), this function is non-destructive.
  1707	 *
  1708	 * Note that we don't pin or otherwise hold the pages referenced that we fault
  1709	 * in.  There's no guarantee that they'll stay in memory for any duration of
  1710	 * time.
  1711	 *
  1712	 * Returns the number of bytes faulted in from @uaddr.
  1713	 */
  1714	size_t fault_in_safe_writeable(const char __user *uaddr, size_t size)
  1715	{
  1716		unsigned long start = (unsigned long)uaddr;
  1717		unsigned long end, nstart, nend;
  1718		struct mm_struct *mm = current->mm;
  1719		struct vm_area_struct *vma = NULL;
  1720		int locked = 0;
  1721	
  1722		/* FIXME: Protect against overflow! */
  1723	
  1724		end = PAGE_ALIGN(start + size);
  1725		for (nstart = start & PAGE_MASK; nstart < end; nstart = nend) {
  1726			unsigned long nr_pages;
  1727			long ret;
  1728	
  1729			if (!locked) {
  1730				locked = 1;
  1731				mmap_read_lock(mm);
  1732				vma = find_vma(mm, nstart);
  1733			} else if (nstart >= vma->vm_end)
  1734				vma = vma->vm_next;
  1735			if (!vma || vma->vm_start >= end)
  1736				break;
  1737			nend = min(end, vma->vm_end);
  1738			if (vma->vm_flags & (VM_IO | VM_PFNMAP))
  1739				continue;
  1740			if (nstart < vma->vm_start)
  1741				nstart = vma->vm_start;
  1742			nr_pages = (nend - nstart) / PAGE_SIZE;
  1743			ret = __get_user_pages_locked(mm, nstart, nr_pages,
  1744						      NULL, NULL, &locked,
  1745						      FOLL_TOUCH | FOLL_WRITE);
  1746			if (ret <= 0)
  1747				break;
  1748			nend = nstart + ret * PAGE_SIZE;
  1749		}
  1750		if (locked)
  1751			mmap_read_unlock(mm);
  1752		if (nstart > start)
> 1753			return min(nstart - start, size);
  1754		return 0;
  1755	}
  1756	EXPORT_SYMBOL(fault_in_safe_writeable);
  1757	

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

Attachment: .config.gz
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