Messages in this thread | ![/](/images/icornerl.gif) | | Date | Wed, 29 Dec 2021 10:01:59 +0800 | From | kernel test robot <> | Subject | [luto:sched/lazymm 14/17] kernel/sched/core.c:4982:15: warning: variable 'old_active_mm' is uninitialized when used here |
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tree: https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git sched/lazymm head: fbea7977edc16ae85f8e2255b084bc2403801327 commit: 8f99be3b9978a71358e03a2bcfd4b230f32714cb [14/17] sched, exec: Factor current mm changes out from exec config: hexagon-randconfig-r041-20211229 (https://download.01.org/0day-ci/archive/20211229/202112290930.hCel1twi-lkp@intel.com/config) compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project 7171af744543433ac75b232eb7dfdaef7efd4d7a) 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/luto/linux.git/commit/?id=8f99be3b9978a71358e03a2bcfd4b230f32714cb git remote add luto https://git.kernel.org/pub/scm/linux/kernel/git/luto/linux.git git fetch --no-tags luto sched/lazymm git checkout 8f99be3b9978a71358e03a2bcfd4b230f32714cb # save the config file to linux build tree mkdir build_dir COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash kernel/sched/
If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp@intel.com>
All warnings (new ones prefixed by >>):
kernel/sched/core.c:3417:6: warning: no previous prototype for function 'sched_set_stop_task' [-Wmissing-prototypes] void sched_set_stop_task(int cpu, struct task_struct *stop) ^ kernel/sched/core.c:3417:1: note: declare 'static' if the function is not intended to be used outside of this translation unit void sched_set_stop_task(int cpu, struct task_struct *stop) ^ static >> kernel/sched/core.c:4982:15: warning: variable 'old_active_mm' is uninitialized when used here [-Wuninitialized] activate_mm(old_active_mm, mm); ^~~~~~~~~~~~~ kernel/sched/core.c:4941:33: note: initialize the variable 'old_active_mm' to silence this warning struct mm_struct *old_active_mm, *mm_to_drop = NULL; ^ = NULL kernel/sched/core.c:2173:20: warning: unused function 'rq_has_pinned_tasks' [-Wunused-function] static inline bool rq_has_pinned_tasks(struct rq *rq) ^ kernel/sched/core.c:5474:20: warning: unused function 'sched_tick_stop' [-Wunused-function] static inline void sched_tick_stop(int cpu) { } ^ kernel/sched/core.c:6202:20: warning: unused function 'sched_core_cpu_deactivate' [-Wunused-function] static inline void sched_core_cpu_deactivate(unsigned int cpu) {} ^ kernel/sched/core.c:6203:20: warning: unused function 'sched_core_cpu_dying' [-Wunused-function] static inline void sched_core_cpu_dying(unsigned int cpu) {} ^ kernel/sched/core.c:9046:20: warning: unused function 'balance_hotplug_wait' [-Wunused-function] static inline void balance_hotplug_wait(void) ^ 7 warnings generated.
vim +/old_active_mm +4982 kernel/sched/core.c
4937 4938 void __change_current_mm(struct mm_struct *mm, bool mm_is_brand_new) 4939 { 4940 struct task_struct *tsk = current; 4941 struct mm_struct *old_active_mm, *mm_to_drop = NULL; 4942 4943 BUG_ON(!mm); /* likely to cause corruption if we continue */ 4944 4945 /* 4946 * We do not want to schedule, nor should procfs peek at current->mm 4947 * while we're modifying it. task_lock() disables preemption and 4948 * locks against procfs. 4949 */ 4950 task_lock(tsk); 4951 /* 4952 * membarrier() requires a full barrier before switching mm. 4953 */ 4954 smp_mb__after_spinlock(); 4955 4956 local_irq_disable(); 4957 4958 if (tsk->mm) { 4959 /* We're detaching from an old mm. Sync stats. */ 4960 sync_mm_rss(tsk->mm); 4961 } else { 4962 /* 4963 * Switching from kernel mm to user. Drop the old lazy 4964 * mm reference. 4965 */ 4966 mm_to_drop = tsk->active_mm; 4967 } 4968 4969 tsk->active_mm = mm; 4970 WRITE_ONCE(tsk->mm, mm); /* membarrier reads this without locks */ 4971 membarrier_update_current_mm(mm); 4972 4973 if (mm_is_brand_new) { 4974 /* 4975 * For historical reasons, some architectures want IRQs on 4976 * when activate_mm() is called. If we're going to call 4977 * activate_mm(), turn on IRQs but leave preemption 4978 * disabled. 4979 */ 4980 if (!IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM)) 4981 local_irq_enable(); > 4982 activate_mm(old_active_mm, mm); 4983 if (IS_ENABLED(CONFIG_ARCH_WANT_IRQS_OFF_ACTIVATE_MM)) 4984 local_irq_enable(); 4985 } else { 4986 switch_mm_irqs_off(old_active_mm, mm, tsk); 4987 local_irq_enable(); 4988 } 4989 4990 /* IRQs are on now. Preemption is still disabled by task_lock(). */ 4991 4992 membarrier_finish_switch_mm(mm); 4993 vmacache_flush(tsk); 4994 task_unlock(tsk); 4995
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