Hi Hoeun, [auto build test WARNING on next-20170208] [also build test WARNING on v4.10-rc7] [cannot apply to linus/master linux/master v4.9-rc8 v4.9-rc7 v4.9-rc6] [if your patch is applied to the wrong git tree, please drop us a note to help improve the system] url: https://github.com/0day-ci/linux/commits/Hoeun-Ryu/fork-free-vmapped-stacks-in-cache-when-cpus-are-offline/20170209-124143 config: i386-randconfig-x004-201706 (attached as .config) compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901 reproduce: # save the attached .config to linux build tree make ARCH=i386 All warnings (new ones prefixed by >>): kernel/fork.c: In function 'free_vm_stack_cache': kernel/fork.c:177:18: error: 'NR_CACHED_STACKS' undeclared (first use in this function) for (i = 0; i < NR_CACHED_STACKS; i++) { ^~~~~~~~~~~~~~~~ kernel/fork.c:177:18: note: each undeclared identifier is reported only once for each function it appears in In file included from include/asm-generic/percpu.h:6:0, from arch/x86/include/asm/percpu.h:542, from arch/x86/include/asm/preempt.h:5, from include/linux/preempt.h:59, from include/linux/spinlock.h:50, from include/linux/mmzone.h:7, from include/linux/gfp.h:5, from include/linux/slab.h:14, from kernel/fork.c:14: kernel/fork.c:178:46: error: 'cached_stacks' undeclared (first use in this function) struct vm_struct *vm_stack = this_cpu_read(cached_stacks[i]); ^ include/linux/percpu-defs.h:305:9: note: in definition of macro '__pcpu_size_call_return' typeof(variable) pscr_ret__; \ ^~~~~~~~ kernel/fork.c:178:32: note: in expansion of macro 'this_cpu_read' struct vm_struct *vm_stack = this_cpu_read(cached_stacks[i]); ^~~~~~~~~~~~~ include/linux/percpu-defs.h:304:1: warning: initialization makes pointer from integer without a cast [-Wint-conversion] ({ \ ^ include/linux/percpu-defs.h:494:29: note: in expansion of macro '__pcpu_size_call_return' #define this_cpu_read(pcp) __pcpu_size_call_return(this_cpu_read_, pcp) ^~~~~~~~~~~~~~~~~~~~~~~ kernel/fork.c:178:32: note: in expansion of macro 'this_cpu_read' struct vm_struct *vm_stack = this_cpu_read(cached_stacks[i]); ^~~~~~~~~~~~~ In file included from arch/x86/include/asm/preempt.h:5:0, from include/linux/preempt.h:59, from include/linux/spinlock.h:50, from include/linux/mmzone.h:7, from include/linux/gfp.h:5, from include/linux/slab.h:14, from kernel/fork.c:14: >> arch/x86/include/asm/percpu.h:94:13: warning: assignment makes integer from pointer without a cast [-Wint-conversion] pto_tmp__ = (val); \ ^ arch/x86/include/asm/percpu.h:416:36: note: in expansion of macro 'percpu_to_op' #define this_cpu_write_1(pcp, val) percpu_to_op("mov", (pcp), val) ^~~~~~~~~~~~ include/linux/percpu-defs.h:364:11: note: in expansion of macro 'this_cpu_write_1' case 1: stem##1(variable, __VA_ARGS__);break; \ ^~~~ include/linux/percpu-defs.h:495:34: note: in expansion of macro '__pcpu_size_call' #define this_cpu_write(pcp, val) __pcpu_size_call(this_cpu_write_, pcp, val) ^~~~~~~~~~~~~~~~ >> kernel/fork.c:183:3: note: in expansion of macro 'this_cpu_write' this_cpu_write(cached_stacks[i], NULL); ^~~~~~~~~~~~~~ >> arch/x86/include/asm/percpu.h:94:13: warning: assignment makes integer from pointer without a cast [-Wint-conversion] pto_tmp__ = (val); \ ^ arch/x86/include/asm/percpu.h:417:36: note: in expansion of macro 'percpu_to_op' #define this_cpu_write_2(pcp, val) percpu_to_op("mov", (pcp), val) ^~~~~~~~~~~~ include/linux/percpu-defs.h:365:11: note: in expansion of macro 'this_cpu_write_2' case 2: stem##2(variable, __VA_ARGS__);break; \ ^~~~ include/linux/percpu-defs.h:495:34: note: in expansion of macro '__pcpu_size_call' #define this_cpu_write(pcp, val) __pcpu_size_call(this_cpu_write_, pcp, val) ^~~~~~~~~~~~~~~~ >> kernel/fork.c:183:3: note: in expansion of macro 'this_cpu_write' this_cpu_write(cached_stacks[i], NULL); ^~~~~~~~~~~~~~ >> arch/x86/include/asm/percpu.h:94:13: warning: assignment makes integer from pointer without a cast [-Wint-conversion] pto_tmp__ = (val); \ ^ arch/x86/include/asm/percpu.h:418:36: note: in expansion of macro 'percpu_to_op' #define this_cpu_write_4(pcp, val) percpu_to_op("mov", (pcp), val) ^~~~~~~~~~~~ include/linux/percpu-defs.h:366:11: note: in expansion of macro 'this_cpu_write_4' case 4: stem##4(variable, __VA_ARGS__);break; \ ^~~~ include/linux/percpu-defs.h:495:34: note: in expansion of macro '__pcpu_size_call' #define this_cpu_write(pcp, val) __pcpu_size_call(this_cpu_write_, pcp, val) ^~~~~~~~~~~~~~~~ >> kernel/fork.c:183:3: note: in expansion of macro 'this_cpu_write' this_cpu_write(cached_stacks[i], NULL); ^~~~~~~~~~~~~~ At top level: kernel/fork.c:173:12: warning: 'free_vm_stack_cache' defined but not used [-Wunused-function] static int free_vm_stack_cache(unsigned int cpu) ^~~~~~~~~~~~~~~~~~~ vim +/this_cpu_write +183 kernel/fork.c 167 * flush. Try to minimize the number of calls by caching stacks. 168 */ 169 #define NR_CACHED_STACKS 2 170 static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]); 171 #endif 172 173 static int free_vm_stack_cache(unsigned int cpu) 174 { 175 int i; 176 177 for (i = 0; i < NR_CACHED_STACKS; i++) { 178 struct vm_struct *vm_stack = this_cpu_read(cached_stacks[i]); 179 if (!vm_stack) 180 continue; 181 182 vfree(vm_stack->addr); > 183 this_cpu_write(cached_stacks[i], NULL); 184 } 185 186 return 0; 187 } 188 189 static unsigned long *alloc_thread_stack_node(struct task_struct *tsk, int node) 190 { 191 #ifdef CONFIG_VMAP_STACK --- 0-DAY kernel test infrastructure Open Source Technology Center https://lists.01.org/pipermail/kbuild-all Intel Corporation