Re: [PATCH v4 06/26] shmem/userfaultfd: Handle uffd-wp special pte in page fault handler

[Peter Xu <peterx@redhat.com>]

On Thu, Jul 15, 2021 at 02:20:21PM +0800, kernel test robot wrote:
> Hi Peter,
> 
> Thank you for the patch! Yet something to improve:
> 
> [auto build test ERROR on linus/master]
> [also build test ERROR on v5.14-rc1 next-20210714]
> [cannot apply to hnaz-linux-mm/master asm-generic/master linux/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/Peter-Xu/userfaultfd-wp-Support-shmem-and-hugetlbfs/20210715-062718
> base:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git 8096acd7442e613fad0354fc8dfdb2003cceea0b
> config: x86_64-randconfig-r021-20210714 (attached as .config)
> compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 0e49c54a8cbd3e779e5526a5888c683c01cc3c50)
> 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
>         # install x86_64 cross compiling tool for clang build
>         # apt-get install binutils-x86-64-linux-gnu
>         # https://github.com/0day-ci/linux/commit/8b3e70f40b8333a803e642ed5c8cce738985881c
>         git remote add linux-review https://github.com/0day-ci/linux
>         git fetch --no-tags linux-review Peter-Xu/userfaultfd-wp-Support-shmem-and-hugetlbfs/20210715-062718
>         git checkout 8b3e70f40b8333a803e642ed5c8cce738985881c
>         # save the attached .config to linux build tree
>         COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 
> 
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@intel.com>
> 
> All errors (new ones prefixed by >>):
> 
> >> mm/memory.c:4167:6: error: implicit declaration of function 'uffd_disable_fault_around' [-Werror,-Wimplicit-function-declaration]
>            if (uffd_disable_fault_around(vmf->vma))
>                ^
>    1 error generated.
> 
> 
> vim +/uffd_disable_fault_around +4167 mm/memory.c
> 
>   4159	
>   4160	/* Return true if we should do read fault-around, false otherwise */
>   4161	static inline bool should_fault_around(struct vm_fault *vmf)
>   4162	{
>   4163		/* No ->map_pages?  No way to fault around... */
>   4164		if (!vmf->vma->vm_ops->map_pages)
>   4165			return false;
>   4166	
> > 4167		if (uffd_disable_fault_around(vmf->vma))
>   4168			return false;
>   4169	
>   4170		return fault_around_bytes >> PAGE_SHIFT > 1;
>   4171	}
>   4172	
> 
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

Will squash this into the patch:

---8<---
diff --git a/include/linux/userfaultfd_k.h b/include/linux/userfaultfd_k.h
index c4228acd1d80..4382240de7c3 100644
--- a/include/linux/userfaultfd_k.h
+++ b/include/linux/userfaultfd_k.h
@@ -283,6 +283,11 @@ static inline bool pte_swp_uffd_wp_special(pte_t pte)
        return false;
 }
 
+static inline bool uffd_disable_fault_around(struct vm_area_struct *vma)
+{
+       return false;
+}
+
 #endif /* CONFIG_USERFAULTFD */
 
 #endif /* _LINUX_USERFAULTFD_K_H */
---8<---

Thanks,

-- 
Peter Xu