Hi Axel,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on arm64/for-next/core]
[also build test ERROR on powerpc/next s390/features tip/perf/core linus/master v5.11-rc3 next-20210115]
[cannot apply to hp-parisc/for-next hnaz-linux-mm/master ia64/next sparc/master]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Axel-Rasmussen/userfaultfd-add-minor-fault-handling/20210116-030900
base:   https://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-next/core
config: i386-randconfig-r013-20210115 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce (this is a W=1 build):
        # https://github.com/0day-ci/linux/commit/97d3dcca13a550a56e5afe40abcc8db929bd3916
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Axel-Rasmussen/userfaultfd-add-minor-fault-handling/20210116-030900
        git checkout 97d3dcca13a550a56e5afe40abcc8db929bd3916
        # save the attached .config to linux build tree
        make W=1 ARCH=i386 

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

All errors (new ones prefixed by >>):

   In file included from include/linux/migrate.h:8,
                    from fs/f2fs/data.c:3857:
   include/linux/hugetlb.h: In function 'want_pmd_share':

quoted

include/linux/hugetlb.h:954:6: error: implicit declaration of function 'uffd_disable_huge_pmd_share' [-Werror=implicit-function-declaration]

     954 |  if (uffd_disable_huge_pmd_share(vma))
         |      ^~~~~~~~~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors
--
   In file included from mm/filemap.c:36:
   include/linux/hugetlb.h: In function 'want_pmd_share':

quoted

include/linux/hugetlb.h:954:6: error: implicit declaration of function 'uffd_disable_huge_pmd_share' [-Werror=implicit-function-declaration]

     954 |  if (uffd_disable_huge_pmd_share(vma))
         |      ^~~~~~~~~~~~~~~~~~~~~~~~~~~
   mm/filemap.c: At top level:
   mm/filemap.c:830:14: warning: no previous prototype for '__add_to_page_cache_locked' [-Wmissing-prototypes]
     830 | noinline int __add_to_page_cache_locked(struct page *page,
         |              ^~~~~~~~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors
--
   In file included from mm/util.c:16:
   include/linux/hugetlb.h: In function 'want_pmd_share':

quoted

include/linux/hugetlb.h:954:6: error: implicit declaration of function 'uffd_disable_huge_pmd_share' [-Werror=implicit-function-declaration]

     954 |  if (uffd_disable_huge_pmd_share(vma))
         |      ^~~~~~~~~~~~~~~~~~~~~~~~~~~
   mm/util.c: In function 'page_mapping':
   mm/util.c:700:15: warning: variable 'entry' set but not used [-Wunused-but-set-variable]
     700 |   swp_entry_t entry;
         |               ^~~~~
   cc1: some warnings being treated as errors
--
   In file included from include/linux/migrate.h:8,
                    from mm/page_alloc.c:61:
   include/linux/hugetlb.h: In function 'want_pmd_share':

quoted

include/linux/hugetlb.h:954:6: error: implicit declaration of function 'uffd_disable_huge_pmd_share' [-Werror=implicit-function-declaration]

     954 |  if (uffd_disable_huge_pmd_share(vma))
         |      ^~~~~~~~~~~~~~~~~~~~~~~~~~~
   mm/page_alloc.c: At top level:
   mm/page_alloc.c:3594:15: warning: no previous prototype for 'should_fail_alloc_page' [-Wmissing-prototypes]
    3594 | noinline bool should_fail_alloc_page(gfp_t gfp_mask, unsigned int order)
         |               ^~~~~~~~~~~~~~~~~~~~~~
   mm/page_alloc.c:6255:23: warning: no previous prototype for 'memmap_init' [-Wmissing-prototypes]
    6255 | void __meminit __weak memmap_init(unsigned long size, int nid,
         |                       ^~~~~~~~~~~
   cc1: some warnings being treated as errors
--
   In file included from kernel/events/core.c:31:
   include/linux/hugetlb.h: In function 'want_pmd_share':

quoted

include/linux/hugetlb.h:954:6: error: implicit declaration of function 'uffd_disable_huge_pmd_share' [-Werror=implicit-function-declaration]

     954 |  if (uffd_disable_huge_pmd_share(vma))
         |      ^~~~~~~~~~~~~~~~~~~~~~~~~~~
   kernel/events/core.c: At top level:
   kernel/events/core.c:6535:6: warning: no previous prototype for 'perf_pmu_snapshot_aux' [-Wmissing-prototypes]
    6535 | long perf_pmu_snapshot_aux(struct perf_buffer *rb,
         |      ^~~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors
--
   In file included from include/linux/migrate.h:8,
                    from kernel/sched/sched.h:53,
                    from kernel/sched/core.c:13:
   include/linux/hugetlb.h: In function 'want_pmd_share':

quoted

include/linux/hugetlb.h:954:6: error: implicit declaration of function 'uffd_disable_huge_pmd_share' [-Werror=implicit-function-declaration]

     954 |  if (uffd_disable_huge_pmd_share(vma))
         |      ^~~~~~~~~~~~~~~~~~~~~~~~~~~
   kernel/sched/core.c: In function 'schedule_tail':
   kernel/sched/core.c:4238:13: warning: variable 'rq' set but not used [-Wunused-but-set-variable]
    4238 |  struct rq *rq;
         |             ^~
   cc1: some warnings being treated as errors
--
   In file included from include/linux/migrate.h:8,
                    from kernel/sched/sched.h:53,
                    from kernel/sched/rt.c:6:
   include/linux/hugetlb.h: In function 'want_pmd_share':

quoted

include/linux/hugetlb.h:954:6: error: implicit declaration of function 'uffd_disable_huge_pmd_share' [-Werror=implicit-function-declaration]

     954 |  if (uffd_disable_huge_pmd_share(vma))
         |      ^~~~~~~~~~~~~~~~~~~~~~~~~~~
   kernel/sched/rt.c: At top level:
   kernel/sched/rt.c:669:6: warning: no previous prototype for 'sched_rt_bandwidth_account' [-Wmissing-prototypes]
     669 | bool sched_rt_bandwidth_account(struct rt_rq *rt_rq)
         |      ^~~~~~~~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors


vim +/uffd_disable_huge_pmd_share +954 include/linux/hugetlb.h

   950	
   951	static inline bool want_pmd_share(struct vm_area_struct *vma)
   952	{
   953	#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE
 > 954		if (uffd_disable_huge_pmd_share(vma))
   955			return false;
   956		return true;
   957	#else
   958		return false;
   959	#endif
   960	}
   961	

---
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