From: Frederic Weisbecker <fweisbec@gmail.com>
To: Rik van Riel <riel@redhat.com>
Cc: paulmck@linux.vnet.ibm.com, luto@amacapital.net,
will.deacon@arm.com, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org, mtosatti@redhat.com, borntraeger@de.ibm.com,
lcapitulino@redhat.com, pbonzini@redhat.com
Subject: Re: [PATCH -v5 6/5] context_tracking: fix exception_enter when already in IN_KERNEL
Date: Thu, 12 Feb 2015 18:00:03 +0100 [thread overview]
Message-ID: <20150212170002.GH18363@lerouge> (raw)
In-Reply-To: <54DCCAFE.7080206@redhat.com>
On Thu, Feb 12, 2015 at 10:47:10AM -0500, Rik van Riel wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On 02/12/2015 10:42 AM, Frederic Weisbecker wrote:
> > On Wed, Feb 11, 2015 at 02:43:19PM -0500, Rik van Riel wrote:
> >> If exception_enter happens when already in IN_KERNEL state, the
> >> code still calls context_tracking_exit, which ends up in
> >> rcu_eqs_exit_common, which explodes with a WARN_ON when it is
> >> called in a situation where dynticks are not enabled.
> >
> > Fortunately context_tracking_exit() already has a current_state ==
> > IN_KERNEL check so this shouldn't be a problem.
>
> No, it had a hard-coded "current_state == IN_USER" check,
> which is very close, but ...
>
> ... I replaced that with a state argument, and forgot to
> ensure that it never gets called with state == IN_KERNEL.
> This patch fixes that.
Ah that's right! Well I'm going to merge this patch to 1/5 then to
avoid breaking bisection.
Thanks.
next prev parent reply other threads:[~2015-02-12 17:00 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-02-10 20:27 [PATCH -v5 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest riel
2015-02-10 20:27 ` [PATCH 1/5] context_tracking: generalize context tracking APIs to support user and guest riel
2015-02-10 21:28 ` Paul E. McKenney
2015-02-10 20:27 ` [PATCH 2/5] nohz: add stub context_tracking_is_enabled riel
2015-02-10 21:29 ` Paul E. McKenney
2015-02-10 20:27 ` [PATCH 3/5] rcu,nohz: run vtime_user_enter/exit only when state == IN_USER riel
2015-02-10 21:35 ` Paul E. McKenney
2015-02-10 20:27 ` [PATCH 4/5] nohz,kvm: export context_tracking_user_enter/exit riel
2015-02-10 21:36 ` Paul E. McKenney
2015-02-10 20:27 ` [PATCH 5/5] kvm,rcu,nohz: use RCU extended quiescent state when running KVM guest riel
2015-02-10 21:42 ` Paul E. McKenney
2015-02-11 19:43 ` [PATCH -v5 6/5] context_tracking: fix exception_enter when already in IN_KERNEL Rik van Riel
2015-02-11 21:27 ` Paul E. McKenney
2015-02-12 15:42 ` Frederic Weisbecker
2015-02-12 15:47 ` Rik van Riel
2015-02-12 17:00 ` Frederic Weisbecker [this message]
2015-02-12 17:48 ` Rik van Riel
2015-02-12 17:09 ` [PATCH -v5 0/5] rcu,nohz,kvm: use RCU extended quiescent state when running KVM guest Frederic Weisbecker
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