Re: [PATCH 05/10] mm/mremap: use an explicit uffd failure path for mremap

[kernel test robot]

Hi Lorenzo,

kernel test robot noticed the following build errors:

[auto build test ERROR on akpm-mm/mm-everything]

url:    https://github.com/intel-lab-lkp/linux/commits/Lorenzo-Stoakes/mm-mremap-perform-some-simple-cleanups/20250707-133132
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/be3e068c77107d385d89eae634317cb59e04e5ba.1751865330.git.lorenzo.stoakes%40oracle.com
patch subject: [PATCH 05/10] mm/mremap: use an explicit uffd failure path for mremap
config: i386-buildonly-randconfig-002-20250707 (https://download.01.org/0day-ci/archive/20250707/202507071505.e2HFMCH2-lkp@xxxxxxxxx/config)
compiler: clang version 20.1.7 (https://github.com/llvm/llvm-project 6146a88f60492b520a36f8f8f3231e15f3cc6082)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20250707/202507071505.e2HFMCH2-lkp@xxxxxxxxx/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
| Closes: https://lore.kernel.org/oe-kbuild-all/202507071505.e2HFMCH2-lkp@xxxxxxxxx/

All errors (new ones prefixed by >>):

>> mm/mremap.c:1739:3: error: call to undeclared function 'mremap_userfaultfd_fail'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
    1739 |                 mremap_userfaultfd_fail(vrm->uf);
         |                 ^
   mm/mremap.c:1739:3: note: did you mean 'mremap_userfaultfd_prep'?
   include/linux/userfaultfd_k.h:363:20: note: 'mremap_userfaultfd_prep' declared here
     363 | static inline void mremap_userfaultfd_prep(struct vm_area_struct *vma,
         |                    ^
   1 error generated.


vim +/mremap_userfaultfd_fail +1739 mm/mremap.c

  1731	
  1732	static void notify_uffd(struct vma_remap_struct *vrm, bool failed)
  1733	{
  1734		struct mm_struct *mm = current->mm;
  1735	
  1736		/* Regardless of success/failure, we always notify of any unmaps. */
  1737		userfaultfd_unmap_complete(mm, vrm->uf_unmap_early);
  1738		if (failed)
> 1739			mremap_userfaultfd_fail(vrm->uf);
  1740		else
  1741			mremap_userfaultfd_complete(vrm->uf, vrm->addr,
  1742				vrm->new_addr, vrm->old_len);
  1743		userfaultfd_unmap_complete(mm, vrm->uf_unmap);
  1744	}
  1745	

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https://github.com/intel/lkp-tests/wiki