From: i@eivanov.com (Evgeniy Ivanov)
Subject: [lttng-dev] Deadlock in call_rcu_thread when destroy rculfhash node with nested rculfhash
Date: Wed, 19 Oct 2016 13:03:47 +0300 [thread overview]
Message-ID: <CAO6Ho0e27-JTmUPrTRZfr95Lm=ri+mOSRNr7Av5Ma0t1ucuH6g@mail.gmail.com> (raw)
In-Reply-To: <CAO6Ho0ea+Mhdoea4b3EL-J4z2wifHPWohq1ps74LQBU+b0-OOQ@mail.gmail.com>
Sorry, found partial answer in docs which state that cds_lfht_destroy
should not be called from a call_rcu thread context. Why does this
limitation exists?
On Wed, Oct 19, 2016 at 12:56 PM, Evgeniy Ivanov <i at eivanov.com> wrote:
> Hi,
>
> Each node of top level rculfhash has nested rculfhash. Some thread clears
> the top level map and then uses rcu_barrier() to wait until everything is
> destroyed (it is done to check leaks). Recently it started to dead lock
> sometimes with following stacks:
>
> Thread1:
>
> __poll
> cds_lfht_destroy <---- nested map
> ...
> free_Node(rcu_head*) <----- node of top level map
> call_rcu_thread
>
> Thread2:
>
> syscall
> rcu_barrier_qsbr
> destroy_all
> main
>
>
> Did call_rcu_thread dead lock with barrier thread? Or is it some kind of
> internal deadlock because of nested maps?
>
>
> --
> Cheers,
> Evgeniy
>
--
Cheers,
Evgeniy
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next prev parent reply other threads:[~2016-10-19 10:03 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-10-19 9:56 Evgeniy Ivanov
2016-10-19 10:03 ` Evgeniy Ivanov [this message]
2016-10-19 15:03 ` Mathieu Desnoyers
2016-10-21 8:19 ` Evgeniy Ivanov
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