Checking for process->mm is not enough because process' main thread may exit or detach its mm via use_mm(), but other threads may still have a valid mm.
To fix this we would need to use find_lock_task_mm(), which would walk up all threads and returns an appropriate task (with task lock held).
clear_tasks_mm_cpumask() has this issue fixed, so let's use it.
Suggested-by: Oleg Nesterov oleg@redhat.com Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org --- arch/arm/kernel/smp.c | 8 +------- 1 file changed, 1 insertion(+), 7 deletions(-)
diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c index addbbe8..e824ee4 100644 --- a/arch/arm/kernel/smp.c +++ b/arch/arm/kernel/smp.c @@ -130,7 +130,6 @@ static void percpu_timer_stop(void); int __cpu_disable(void) { unsigned int cpu = smp_processor_id(); - struct task_struct *p; int ret;
ret = platform_cpu_disable(cpu); @@ -160,12 +159,7 @@ int __cpu_disable(void) flush_cache_all(); local_flush_tlb_all();
- read_lock(&tasklist_lock); - for_each_process(p) { - if (p->mm) - cpumask_clear_cpu(cpu, mm_cpumask(p->mm)); - } - read_unlock(&tasklist_lock); + clear_tasks_mm_cpumask(cpu);
return 0; }