On Mon, Sep 01, 2014 at 07:58:51PM +0200, Oleg Nesterov wrote: > However, the very fact that another CPU can look at this task_struct > means that we still need spin_unlock_wait(). If nothing else to ensure > that try_to_wake_up()->spin_unlock(pi_lock) won't write into the memory > we are are going to free.
task_struct is RCU freed, if it still has a 'reference' to the task, it shouldn't be going 'away', right? > So I think the comment in do exit should be updated too, and smp_mb() > should be moved under raw_spin_unlock_wait() but ... > > But. If am right, doesn't this mean we that have even more problems with > postmortem wakeups??? Why ttwu() can't _start_ after spin_unlock_wait ? ttwu should bail at: if (!(p->state & state)) goto out; That should never match with TASK_DEAD. Either that; or I should go sleep already :-) I shifted 7 hours yesterday, so I'm still somewhat jet-lagged. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
