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| -rw-r--r-- | kernel/exit.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/kernel/exit.c b/kernel/exit.c index 294b1709170d..4b4042f9bc6a 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -1038,6 +1038,22 @@ void do_exit(long code) if (tsk->nr_dirtied) __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied); exit_rcu(); + + /* + * The setting of TASK_RUNNING by try_to_wake_up() may be delayed + * when the following two conditions become true. + * - There is race condition of mmap_sem (It is acquired by + * exit_mm()), and + * - SMI occurs before setting TASK_RUNINNG. + * (or hypervisor of virtual machine switches to other guest) + * As a result, we may become TASK_RUNNING after becoming TASK_DEAD + * + * To avoid it, we have to wait for releasing tsk->pi_lock which + * is held by try_to_wake_up() + */ + smp_mb(); + raw_spin_unlock_wait(&tsk->pi_lock); + /* causes final put_task_struct in finish_task_switch(). */ tsk->state = TASK_DEAD; tsk->flags |= PF_NOFREEZE; /* tell freezer to ignore us */ |