On 10/17, Michal Hocko wrote: > > I think we should rather get back to __thaw_task here.
Yes, agreed. > Andrew could you replace the previous version by this one, please? Yes, that patch should be dropped... And can't resist... please look at http://marc.info/?l=linux-kernel&m=138427535430827 ;) > --- a/kernel/freezer.c > +++ b/kernel/freezer.c > @@ -45,13 +45,28 @@ bool freezing_slow_path(struct task_struct *p) > if (pm_nosig_freezing || cgroup_freezing(p)) > return true; > > - if (pm_freezing && !(p->flags & PF_KTHREAD)) > + if (!(p->flags & PF_KTHREAD)) Why? Doesn't this mean that try_to_freeze() can race with thaw_processes() and then this task can be frozen for no reazon? > +static bool should_thaw_current(bool check_kthr_stop) > +{ > + if (!freezing(current)) > + return true; > + > + if (check_kthr_stop && kthread_should_stop()) > + return true; > + > + /* It might not be safe to check TIF_MEMDIE for pm freeze. */ > + if (cgroup_freezing(current) && test_thread_flag(TIF_MEMDIE)) I still think that the comment should tell more to explain why this is not safe. And if this is not safe, it is not clear how/why cgroup_freezing() can save us, both pm_freezing and CGROUP_FREEZING can be true? And I think that this TIF_MEMDIE should go into freezing_slow_path(), so we do not even need should_thaw_current(). This also looks more safe to me. Suppose that a task does while (try_to_freeze()) ; Yes, this is pointless but correct. And in fact I think this pattern is possible. If this task is killed by OOM, it will spin forever. Oleg. -- 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/
