Hi Qi, Thank you for the patch! Yet something to improve: [auto build test ERROR on hnaz-mm/master] [also build test ERROR on linus/master next-20211111] [cannot apply to tip/perf/core tip/x86/core v5.15] [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/Qi-Zheng/Free-user-PTE-page-table-pages/20211110-185837 base: https://github.com/hnaz/linux-mm master config: ia64-defconfig (attached as .config) compiler: ia64-linux-gcc (GCC) 11.2.0 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://github.com/0day-ci/linux/commit/6e3cc5bb722cbd2fc4170d2f5371e52792d17d2e git remote add linux-review https://github.com/0day-ci/linux git fetch --no-tags linux-review Qi-Zheng/Free-user-PTE-page-table-pages/20211110-185837 git checkout 6e3cc5bb722cbd2fc4170d2f5371e52792d17d2e # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=ia64 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot All errors (new ones prefixed by >>): In file included from arch/ia64/include/uapi/asm/gcc_intrin.h:11, from arch/ia64/include/asm/gcc_intrin.h:10, from arch/ia64/include/uapi/asm/intrinsics.h:20, from arch/ia64/include/asm/intrinsics.h:11, from arch/ia64/include/asm/page.h:11, from arch/ia64/include/asm/pgtable.h:18, from include/linux/pgtable.h:6, from include/linux/pte_ref.h:10, from mm/pte_ref.c:8: mm/pte_ref.c: In function 'pte_try_get': >> mm/pte_ref.c:37:22: error: implicit declaration of function 'is_huge_pmd'; did you mean 'zap_huge_pmd'? [-Werror=implicit-function-declaration] 37 | if (unlikely(is_huge_pmd(*pmd))) | ^~~~~~~~~~~ include/linux/compiler.h:78:45: note: in definition of macro 'unlikely' 78 | # define unlikely(x) __builtin_expect(!!(x), 0) | ^ cc1: some warnings being treated as errors vim +37 mm/pte_ref.c e03404013f81d7 Qi Zheng 2021-11-10 20 e03404013f81d7 Qi Zheng 2021-11-10 21 /* e03404013f81d7 Qi Zheng 2021-11-10 22 * pte_try_get - Try to increment refcount for the PTE page table. e03404013f81d7 Qi Zheng 2021-11-10 23 * @pmd: a pointer to the pmd entry corresponding to the PTE page table. e03404013f81d7 Qi Zheng 2021-11-10 24 * e03404013f81d7 Qi Zheng 2021-11-10 25 * Return true if the increment succeeded. Otherwise return false. e03404013f81d7 Qi Zheng 2021-11-10 26 * e03404013f81d7 Qi Zheng 2021-11-10 27 * Before Operating the PTE page table, we need to hold a refcount e03404013f81d7 Qi Zheng 2021-11-10 28 * to protect against the concurrent release of the PTE page table. e03404013f81d7 Qi Zheng 2021-11-10 29 * But we will fail in the following case: e03404013f81d7 Qi Zheng 2021-11-10 30 * - The content mapped in @pmd is not a PTE page e03404013f81d7 Qi Zheng 2021-11-10 31 * - The refcount of the PTE page table is zero, it will be freed e03404013f81d7 Qi Zheng 2021-11-10 32 */ e03404013f81d7 Qi Zheng 2021-11-10 33 enum pte_tryget_type pte_try_get(pmd_t *pmd) e03404013f81d7 Qi Zheng 2021-11-10 34 { e03404013f81d7 Qi Zheng 2021-11-10 35 if (unlikely(pmd_none(*pmd))) e03404013f81d7 Qi Zheng 2021-11-10 36 return TRYGET_FAILED_NONE; e03404013f81d7 Qi Zheng 2021-11-10 @37 if (unlikely(is_huge_pmd(*pmd))) e03404013f81d7 Qi Zheng 2021-11-10 38 return TRYGET_FAILED_HUGE_PMD; e03404013f81d7 Qi Zheng 2021-11-10 39 e03404013f81d7 Qi Zheng 2021-11-10 40 return TRYGET_SUCCESSED; e03404013f81d7 Qi Zheng 2021-11-10 41 } e03404013f81d7 Qi Zheng 2021-11-10 42 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org