tree: https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git sched/core head: 3124fc8676c43f13e7b133644c8a918e7d5dbf0f commit: d8ad4c3c8c3417d895aeaf05cb11d3b817e813c5 [6/8] sched: avoid scale real weight down to zero config: alpha-defconfig (attached as .config) compiler: alpha-linux-gcc (GCC) 9.2.0 reproduce: wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross chmod +x ~/bin/make.cross git checkout d8ad4c3c8c3417d895aeaf05cb11d3b817e813c5 # save the attached .config to linux build tree GCC_VERSION=9.2.0 make.cross ARCH=alpha If you fix the issue, kindly add following tag Reported-by: kbuild test robot <lkp(a)intel.com&gt; All error/warnings (new ones prefixed by >>): In file included from include/asm-generic/bug.h:19, from arch/alpha/include/asm/bug.h:23, from include/linux/bug.h:5, from include/linux/thread_info.h:12, from include/asm-generic/current.h:5, from ./arch/alpha/include/generated/asm/current.h:1, from include/linux/sched.h:12, from kernel/sched/sched.h:5, from kernel/sched/fair.c:23: kernel/sched/fair.c: In function '__update_inv_weight': 125 | __w = max(MIN_SHARES, __w >> SCHED_FIXEDPOINT_SHIFT); \ | ^~~~~~~~~~ include/linux/kernel.h:835:22: note: in definition of macro '__typecheck' 835 | (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1))) | ^ include/linux/kernel.h:859:24: note: in expansion of macro '__safe_cmp' 859 | __builtin_choose_expr(__safe_cmp(x, y), \ | ^~~~~~~~~~ include/linux/kernel.h:875:19: note: in expansion of macro '__careful_cmp' 875 | #define max(x, y) __careful_cmp(x, y, >) | ^~~~~~~~~~~~~ 125 | __w = max(MIN_SHARES, __w >> SCHED_FIXEDPOINT_SHIFT); \ | ^~~ 209 | w = scale_load_down(lw->weight); | ^~~~~~~~~~~~~~~ kernel/sched/sched.h:125:13: note: each undeclared identifier is reported only once for each function it appears in 125 | __w = max(MIN_SHARES, __w >> SCHED_FIXEDPOINT_SHIFT); \ | ^~~~~~~~~~ include/linux/kernel.h:835:22: note: in definition of macro '__typecheck' 835 | (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1))) | ^ include/linux/kernel.h:859:24: note: in expansion of macro '__safe_cmp' 859 | __builtin_choose_expr(__safe_cmp(x, y), \ | ^~~~~~~~~~ include/linux/kernel.h:875:19: note: in expansion of macro '__careful_cmp' 875 | #define max(x, y) __careful_cmp(x, y, >) | ^~~~~~~~~~~~~ 125 | __w = max(MIN_SHARES, __w >> SCHED_FIXEDPOINT_SHIFT); \ | ^~~ 209 | w = scale_load_down(lw->weight); | ^~~~~~~~~~~~~~~ 859 | __builtin_choose_expr(__safe_cmp(x, y), \ | ^~~~~~~~~~~~~~~~~~~~~ include/linux/kernel.h:875:19: note: in expansion of macro '__careful_cmp' 875 | #define max(x, y) __careful_cmp(x, y, >) | ^~~~~~~~~~~~~ 125 | __w = max(MIN_SHARES, __w >> SCHED_FIXEDPOINT_SHIFT); \ | ^~~ 209 | w = scale_load_down(lw->weight); | ^~~~~~~~~~~~~~~ kernel/sched/fair.c: In function '__calc_delta': 125 | __w = max(MIN_SHARES, __w >> SCHED_FIXEDPOINT_SHIFT); \ | ^~~~~~~~~~ include/linux/kernel.h:835:22: note: in definition of macro '__typecheck' 835 | (!!(sizeof((typeof(x) *)1 == (typeof(y) *)1))) | ^ include/linux/kernel.h:859:24: note: in expansion of macro '__safe_cmp' 859 | __builtin_choose_expr(__safe_cmp(x, y), \ | ^~~~~~~~~~ include/linux/kernel.h:875:19: note: in expansion of macro '__careful_cmp' 875 | #define max(x, y) __careful_cmp(x, y, >) | ^~~~~~~~~~~~~ 125 | __w = max(MIN_SHARES, __w >> SCHED_FIXEDPOINT_SHIFT); \ | ^~~ kernel/sched/fair.c:233:13: note: in expansion of macro 'scale_load_down' 233 | u64 fact = scale_load_down(weight); | ^~~~~~~~~~~~~~~ 859 | __builtin_choose_expr(__safe_cmp(x, y), \ | ^~~~~~~~~~~~~~~~~~~~~ include/linux/kernel.h:875:19: note: in expansion of macro '__careful_cmp' 875 | #define max(x, y) __careful_cmp(x, y, >) | ^~~~~~~~~~~~~ 125 | __w = max(MIN_SHARES, __w >> SCHED_FIXEDPOINT_SHIFT); \ | ^~~ kernel/sched/fair.c:233:13: note: in expansion of macro 'scale_load_down' 233 | u64 fact = scale_load_down(weight); | ^~~~~~~~~~~~~~~ vim +/MIN_SHARES +125 kernel/sched/sched.h 103 104 /* 105 * Increase resolution of nice-level calculations for 64-bit architectures. 106 * The extra resolution improves shares distribution and load balancing of 107 * low-weight task groups (eg. nice +19 on an autogroup), deeper taskgroup 108 * hierarchies, especially on larger systems. This is not a user-visible change 109 * and does not change the user-interface for setting shares/weights. 110 * 111 * We increase resolution only if we have enough bits to allow this increased 112 * resolution (i.e. 64-bit). The costs for increasing resolution when 32-bit 113 * are pretty high and the returns do not justify the increased costs. 114 * 115 * Really only required when CONFIG_FAIR_GROUP_SCHED=y is also set, but to 116 * increase coverage and consistency always enable it on 64-bit platforms. 117 */ 118 #ifdef CONFIG_64BIT 119 # define NICE_0_LOAD_SHIFT (SCHED_FIXEDPOINT_SHIFT + SCHED_FIXEDPOINT_SHIFT) 120 # define scale_load(w) ((w) << SCHED_FIXEDPOINT_SHIFT) 121 # define scale_load_down(w) \ 122 ({ \ 123 unsigned long __w = (w); \ 124 if (__w) \ 126 __w; \ 127 }) 128 #else 129 # define NICE_0_LOAD_SHIFT (SCHED_FIXEDPOINT_SHIFT) 130 # define scale_load(w) (w) 131 # define scale_load_down(w) (w) 132 #endif 133 --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org