[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
2021-08-04T01:35:12Z

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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@intel.com>

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@lists.01.org

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