Hi Chuanhong, First bad commit (maybe != root cause): tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: d5ad8ec3cfb56a017de6a784835666475b4be349 commit: 1f0400d0e2c410b04f246aefb2e9b5155eb4b0bf mips: ralink: enable zboot support date: 10 months ago config: mips-randconfig-r022-20210803 (attached as .config) compiler: mips-linux-gcc (GCC) 10.3.0 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://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=1f0400d0e2c410b04f246aefb2e9b5155eb4b0bf git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git git fetch --no-tags linus master git checkout 1f0400d0e2c410b04f246aefb2e9b5155eb4b0bf # save the attached .config to linux build tree COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-10.3.0 make.cross ARCH=mips If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot All warnings (new ones prefixed by >>): arch/mips/boot/compressed/decompress.c:38:6: warning: no previous prototype for 'error' [-Wmissing-prototypes] 38 | void error(char *x) | ^~~~~ In file included from arch/mips/boot/compressed/../../../../lib/decompress_unlz4.c:10, from arch/mips/boot/compressed/decompress.c:60: arch/mips/boot/compressed/../../../../lib/lz4/lz4_decompress.c:480:5: warning: no previous prototype for 'LZ4_decompress_safe_withPrefix64k' [-Wmissing-prototypes] 480 | int LZ4_decompress_safe_withPrefix64k(const char *source, char *dest, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> arch/mips/boot/compressed/../../../../lib/lz4/lz4_decompress.c:502:5: warning: no previous prototype for 'LZ4_decompress_safe_forceExtDict' [-Wmissing-prototypes] 502 | int LZ4_decompress_safe_forceExtDict(const char *source, char *dest, | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ arch/mips/boot/compressed/decompress.c:81:6: warning: no previous prototype for '__stack_chk_fail' [-Wmissing-prototypes] 81 | void __stack_chk_fail(void) | ^~~~~~~~~~~~~~~~ arch/mips/boot/compressed/decompress.c:86:6: warning: no previous prototype for 'decompress_kernel' [-Wmissing-prototypes] 86 | void decompress_kernel(unsigned long boot_heap_start) | ^~~~~~~~~~~~~~~~~ vim +/LZ4_decompress_safe_forceExtDict +502 arch/mips/boot/compressed/../../../../lib/lz4/lz4_decompress.c cffb78b0e0b3a3 Kyungsik Lee 2013-07-08 501 2209fda323e2fd Gao Xiang 2018-10-30 @502 int LZ4_decompress_safe_forceExtDict(const char *source, char *dest, 2209fda323e2fd Gao Xiang 2018-10-30 503 int compressedSize, int maxOutputSize, 2209fda323e2fd Gao Xiang 2018-10-30 504 const void *dictStart, size_t dictSize) 2209fda323e2fd Gao Xiang 2018-10-30 505 { 2209fda323e2fd Gao Xiang 2018-10-30 506 return LZ4_decompress_generic(source, dest, 2209fda323e2fd Gao Xiang 2018-10-30 507 compressedSize, maxOutputSize, 2209fda323e2fd Gao Xiang 2018-10-30 508 endOnInputSize, decode_full_block, 2209fda323e2fd Gao Xiang 2018-10-30 509 usingExtDict, (BYTE *)dest, 2209fda323e2fd Gao Xiang 2018-10-30 510 (const BYTE *)dictStart, dictSize); 2209fda323e2fd Gao Xiang 2018-10-30 511 } 2209fda323e2fd Gao Xiang 2018-10-30 512 :::::: The code at line 502 was first introduced by commit :::::: 2209fda323e2fd2a2d0885595fd5097717f8d2aa lib/lz4: update LZ4 decompressor module :::::: TO: Gao Xiang :::::: CC: Linus Torvalds --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org