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 the issue fixed, so let's use it.
Suggested-by: Oleg Nesterov oleg@redhat.com Signed-off-by: Anton Vorontsov anton.vorontsov@linaro.org --- arch/sh/kernel/smp.c | 7 +------ 1 file changed, 1 insertion(+), 6 deletions(-)
diff --git a/arch/sh/kernel/smp.c b/arch/sh/kernel/smp.c index eaebdf6..4664f76 100644 --- a/arch/sh/kernel/smp.c +++ b/arch/sh/kernel/smp.c @@ -123,7 +123,6 @@ void native_play_dead(void) int __cpu_disable(void) { unsigned int cpu = smp_processor_id(); - struct task_struct *p; int ret;
ret = mp_ops->cpu_disable(cpu); @@ -153,11 +152,7 @@ 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; }