Hi Peter,

Thank you for the patch! Yet something to improve:

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

url:    https://github.com/intel-lab-lkp/linux/commits/Peter-Xu/mm-uffd-Always-wr-protect-pte-in-pte_mkuffd_wp/20221206-050912
base:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-everything
patch link:    https://lore.kernel.org/r/Y45duzmGGUT0%2Bu8t%40x1n
patch subject: [PATCH] mm/uffd: Always wr-protect pte in pte_mkuffd_wp()
config: x86_64-randconfig-a004-20221205
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
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://github.com/intel-lab-lkp/linux/commit/ddd9626e3f22a7c2c263c0db4d062a7cc60dfa15
        git remote add linux-review https://github.com/intel-lab-lkp/linux
        git fetch --no-tags linux-review Peter-Xu/mm-uffd-Always-wr-protect-pte-in-pte_mkuffd_wp/20221206-050912
        git checkout ddd9626e3f22a7c2c263c0db4d062a7cc60dfa15
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=x86_64 prepare

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   make[5]: *** No rule to make target 'tools/include/uapi/linux/stddef.h', needed by 'tools/bpf/resolve_btfids/libbpf/staticobjs/libbpf.o'.  Stop.
   make[4]: *** [Makefile:157: tools/bpf/resolve_btfids/libbpf/staticobjs/libbpf-in.o] Error 2
   make[4]: *** Waiting for unfinished jobs....
   make[3]: *** [Makefile:55: tools/bpf/resolve_btfids//libbpf/libbpf.a] Error 2
   make[2]: *** [Makefile:76: bpf/resolve_btfids] Error 2
   make[1]: *** [Makefile:1423: tools/bpf/resolve_btfids] Error 2
   In file included from arch/x86/kernel/asm-offsets.c:13:
   In file included from include/linux/suspend.h:5:
   In file included from include/linux/swap.h:9:
   In file included from include/linux/memcontrol.h:20:
   In file included from include/linux/mm.h:29:
   In file included from include/linux/pgtable.h:6:
>> arch/x86/include/asm/pgtable.h:316:9: error: implicit declaration of function 'pte_wrprotect' is invalid in C99 [-Werror,-Wimplicit-function-declaration]
           return pte_wrprotect(pte_set_flags(pte, _PAGE_UFFD_WP));
                  ^
>> arch/x86/include/asm/pgtable.h:316:9: error: returning 'int' from a function with incompatible result type 'pte_t'
           return pte_wrprotect(pte_set_flags(pte, _PAGE_UFFD_WP));
                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>> arch/x86/include/asm/pgtable.h:335:21: error: static declaration of 'pte_wrprotect' follows non-static declaration
   static inline pte_t pte_wrprotect(pte_t pte)
                       ^
   arch/x86/include/asm/pgtable.h:316:9: note: previous implicit declaration is here
           return pte_wrprotect(pte_set_flags(pte, _PAGE_UFFD_WP));
                  ^
   3 errors generated.
   make[2]: *** [scripts/Makefile.build:118: arch/x86/kernel/asm-offsets.s] Error 1
   make[2]: Target 'prepare' not remade because of errors.
   make[1]: *** [Makefile:1270: prepare0] Error 2
   make[1]: Target 'prepare' not remade because of errors.
   make: *** [Makefile:231: __sub-make] Error 2
   make: Target 'prepare' not remade because of errors.


vim +/pte_wrprotect +316 arch/x86/include/asm/pgtable.h

   313	
   314	static inline pte_t pte_mkuffd_wp(pte_t pte)
   315	{
 > 316		return pte_wrprotect(pte_set_flags(pte, _PAGE_UFFD_WP));
   317	}
   318	
   319	static inline pte_t pte_clear_uffd_wp(pte_t pte)
   320	{
   321		return pte_clear_flags(pte, _PAGE_UFFD_WP);
   322	}
   323	#endif /* CONFIG_HAVE_ARCH_USERFAULTFD_WP */
   324	
   325	static inline pte_t pte_mkclean(pte_t pte)
   326	{
   327		return pte_clear_flags(pte, _PAGE_DIRTY);
   328	}
   329	
   330	static inline pte_t pte_mkold(pte_t pte)
   331	{
   332		return pte_clear_flags(pte, _PAGE_ACCESSED);
   333	}
   334	
 > 335	static inline pte_t pte_wrprotect(pte_t pte)
   336	{
   337		return pte_clear_flags(pte, _PAGE_RW);
   338	}
   339	

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