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Date: Tue, 17 Mar 2015 20:24:50 +0100 From: Oleg Nesterov <oleg@...hat.com> To: Aaron Tomlin <atomlin@...hat.com> Cc: akpm@...ux-foundation.org, rientjes@...gle.com, dwysocha@...hat.com, linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...nel.org> Subject: [PATCH 0/2] hung_task: improve rcu_lock_break() logic On 03/17, Oleg Nesterov wrote: > > On 03/17, Aaron Tomlin wrote: > > > > --- a/kernel/hung_task.c > > +++ b/kernel/hung_task.c > > @@ -169,7 +169,7 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) > > return; > > > > rcu_read_lock(); > > - do_each_thread(g, t) { > > + for_each_process_thread(g, t) { > > if (!max_count--) > > goto unlock; > > if (!--batch_count) { > > @@ -180,7 +180,7 @@ static void check_hung_uninterruptible_tasks(unsigned long timeout) > > /* use "==" to skip the TASK_KILLABLE tasks waiting on NFS */ > > if (t->state == TASK_UNINTERRUPTIBLE) > > check_hung_task(t, timeout); > > - } while_each_thread(g, t); > > + } > > > Acked-by: Oleg Nesterov <oleg@...hat.com> > > > > Perhaps it also makes sense to improve this rcu_lock_break a bit... > For example, if 't' is dead but 'g' is alive we can continue the > "for_each_process" part of this double loop. And if 't' is still > alive then we can find the new leader and continue... > > But I agree, lets start from this fix, then we will see. Something like this. on top of Aaron's change. But actually I am not sure this really makes a lot of sense. But if yes, we can do more. We can save g->start_time before rcu_lock_break(), and then "both dead" case can use for_each_process() to (try to) find the first process whis has a ge start_time. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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